JP2007302956A - Nonfired agglomerated ore for iron manufacture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide nonfired agglomerated ore for iron manufacture which has high strength in spite of small additive quantity of a binder and can be manufactured without using a special molding method etc. <P>SOLUTION: The nonfired agglomerated ore is obtained by preparing a raw material in which a binder (B) is blended with an iron raw material (A) for iron manufacture and solidifying the raw material into agglomerates, where the cumulative volume fraction P(%) of the raw material of ≥d(mm) particle diameter satisfies 100×(d/D)<SP>0.1</SP>≤P≤100×(d/D)<SP>0.4</SP>(where D is the maximum particle diameter (mm) of raw-material particles). By regulating particle size distribution of the raw material to optimize porosity in the raw material, the efficiency of the binder acting among the raw-material particles can be increased and high strength can be provided in spite of the use of the binder in a small quantity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an unfired agglomerated ore for iron making used as an iron raw material in an iron making furnace such as a blast furnace.

  In a pig iron manufacturing process performed using a solid iron furnace such as a blast furnace (hereinafter described as an example of a blast furnace), the porosity in the raw material packed bed is used to distribute the reducing gas in the raw material packed bed in the furnace. It is important to keep the above a certain value. For this reason, it is desirable that the furnace interior inclusions such as iron raw materials have a large particle size distribution, and it is necessary to increase the strength of the charges that may be pulverized after charging to suppress pulverization. For this reason, especially in large blast furnaces, sintered ore obtained by baking powdered ore with the heat of combustion of carbonaceous materials, or fired pellets obtained by forming powdered ore into a spherical shape with a pelletizer and then heat-hardening at 1000 ° C or higher Is widely used.

  On the other hand, studies on non-fired agglomerated minerals not subjected to high-temperature heat treatment have also been promoted, particularly for the purpose of energy saving. This non-calcined agglomerated mineral is required to have a strength that can withstand an impact in the blast furnace and in the blast furnace. Conventionally, the strength is expressed by adding cement or the like as a binder. That is, this type of non-fired agglomerated mineral is granulated into a lump by adding a hydraulic binder such as cement to an iron oxide raw material such as sintered or iron ore powder, and this is used at room temperature or waste heat. Manufactured by curing for a certain period of time at a relatively low temperature of several hundred degrees C or less. There are methods such as pelletizing and briquetting as granulation methods for this agglomerate.

On the other hand, Patent Document 1 discloses a method for producing a non-fired agglomerated ore which is agglomerated by adding a binder and, if necessary, moisture to a granular ore mainly composed of iron ore. In order to eliminate the density of the packing density, a technique is disclosed in which a molding pressure of 0.3 kg / cm ² or more is applied and molding is performed while applying an appropriate vibration.
Moreover, in patent document 2, 1 type or 2 types of returned ore and sintered under sieve powder, and the mixed powder of dust finer than this are knead | mixed with 1-6 mass% molasses or its dilution liquid, A technique of agglomerating to a particle size of 1 mm or more with a molding machine after curing at room temperature for a predetermined time is disclosed.
JP 58-37137 A JP 7-224329 A

However, conventional non-fired agglomerated minerals obtained by adding cement or other binders to iron oxide raw materials such as sintered ore or iron ore powders, ensure the required strength with a small amount of binder. However, it is necessary to add a large amount of binder to ensure strength. For this reason, there existed problems, such as high manufacturing cost and the amount of slag of a blast furnace increasing.
Further, the method of Patent Document 1 has a problem in manufacturing cost because the forming roll is worn when the raw material is briquetted with the forming roll. Moreover, in the method of Patent Document 2, it is necessary to add a certain amount of binder in order to impart a predetermined strength to the agglomerate, which increases the production cost and increases the amount of slag in the blast furnace. There is a problem.

  Accordingly, an object of the present invention is to solve such problems of the prior art, have high strength with a small amount of added binder, and can be produced without using a special molding method or the like. It is to provide the ore.

As a result of repeated studies to solve the above problems on the premise that the raw material in which the binder is mixed with the iron raw material for iron making can be agglomerated by pelletizing or briquetting, etc., the inventors have determined the particle size distribution of the raw material. It was found that by adjusting and optimizing the porosity in the raw material, the efficiency of the binder working between the raw material particles is increased, and a non-fired agglomerated ore for iron making having a high strength with a small amount of binder is obtained.
The present invention has been made based on such findings, and the gist thereof is as follows.

[1] An unfired agglomerated mineral obtained by solidifying a raw material in which the binder (B) is blended with the iron raw material (A) for iron making,
A non-fired agglomerated ore for iron making, wherein a cumulative volume fraction P (%) of a raw material having a particle size of d (mm) or more satisfies the following formula (1):
100 × (d / D) ^0.1 ≦ P ≦ 100 × (d / D) ^0.4 (1)
D: Maximum particle diameter in raw material particles (mm)
[2] The non-fired agglomerate for iron making according to [1], wherein d is 0.001 to 0.2 mm and D is 2 to 5 mm.
[3] The non-fired agglomerate for iron making according to [1] or [2], wherein the blending amount of the binder (B) in the raw material is 10 mass% or less.

[4] In the unfired agglomerated ore for iron making according to any one of [1] to [3] above, the agglomerated mineral is either a solidified product of a granulated product, a solidified product of a molded product, or a crushed product of a solidified product. A non-fired agglomerated ore for iron making, characterized in that it exists.
[5] The unfired agglomerated ore for iron making according to any one of [1] to [4] above, wherein the iron raw material for iron making (A) is a fine-grained sintered ore and / or fine-grained iron ore. Non-calcined agglomerate for iron making.
[6] In the unfired agglomerated ore for iron making according to any one of [1] to [5] above, the iron oxide-containing powder (C) in which the ratio of the particle size of 10 μm or less is 90 mass% or more is included in the raw material The non-fired agglomerated mineral for iron making according to claim 1, wherein the powder is composed of only iron oxide.
[7] The non-calcined agglomerate for iron making of [6] above, wherein the amount of iron oxide-containing powder (C) in the raw material is 1 to 30 mass% in terms of iron oxide, Firing agglomerates.

  The non-fired agglomerated ore for iron making of the present invention has high strength with a small amount of added binder, and can be produced by a method such as general pelletizing or briquetting without using a special molding method. it can. Therefore, pulverization due to impact in the blast furnace or in the blast furnace can be suppressed, and since the amount of binder added is small, the manufacturing cost is low compared to conventional unfired agglomerated minerals, and the slag of the blast furnace It is also advantageous for reducing the amount.

The non-fired agglomerated ore for iron making of the present invention is a non-fired agglomerated mineral obtained by solidifying a raw material in which a binder (B) is blended with an iron raw material for iron making (A), and having a particle size of d (mm) or more. The cumulative volume ratio P (%) of the raw material satisfies the following formula (1).
100 × (d / D) ^0.1 ≦ P ≦ 100 × (d / D) ^0.4 (1)
D: Maximum particle diameter in raw material particles (mm)
Examples of the iron raw material for iron making (A) include fine-grained sintered ore and fine-grained iron ore, but are not limited thereto, and can be used as an iron raw material for an iron making furnace. Then, it is sufficient if it is a fine granular material that cannot be charged into a vertical iron furnace (hereinafter described as an example of a blast furnace).

A typical example of the fine-grained sintered ore is a sintered ore powder called return ore in the iron ore sintering process. In the conventional general sintering process, this sintered ore powder is sent back to the sintering process. It is used as a sintering raw material. Most of the sintered ore powder is generated in the particle size selection process when obtaining the product sintered ore, but there are also those generated in the transport process to the blast furnace and around the blast furnace. In the conventional sintering process, the product yield is about 70 to 80%, and the remaining 20 to 30% is returned to the sintering process as a return mineral (sintered ore powder) (that is, the product sintered ore). Circulates within the process without becoming). Therefore, by using such sintered ore powder as the iron raw material (A) for non-fired agglomerated minerals of the present invention, the total yield of agglomerated ores including sintered ore can be greatly improved. it can.
The fine-grained iron ore includes iron ore powder. Moreover, any of iron ore having a small particle size and iron ore having a small particle size generated in the sizing process may be used.
Two or more different types of iron raw materials (A) for iron making may be used. The particle size of the iron raw material (A) for iron making is generally less than 5 mm.

The binder (B) is not particularly limited as long as it can be solidified by hydration hardening or hydrogen bonding accompanying water evaporation, and exhibit a binder function for bonding raw material particles. Specifically, a hydraulic binder, an organic binder (organic substance), or the like can be used. Examples of hydraulic binders include cement (blast furnace cement, Portland cement, fly ash cement, alumina cement, etc.), granulated blast furnace slag, gypsum, and the like, and organic binders include starch. Examples thereof include hydrogen-bonding polymer substances (organic substances) having strong hydrogen bonds such as saccharides and polyacrylamides.
The strength of the non-fired agglomerated mineral can be increased as the blending amount of the binder (B) increases, but the production cost increases as the blending amount increases, and the proportion of the iron raw material (A) for iron making decreases. Sex is reduced. On the other hand, when there are too few compounding quantities of a binder (B), sufficient intensity | strength in cold will not be acquired and the non-baking agglomerated mineral will be pulverized. The present invention aims to ensure high strength (cold altitude) with a small amount of binder.

The following formula (a) is known as a formula representing a state in which the filling degree of the powdery raw material is the highest (a state in which the porosity in the raw material is the smallest).
P = 100 × (d ₀ / D) ^q (a)
Where P: Cumulative volume ratio (%)
d ₀ : Raw material particle diameter (mm)
D: Maximum particle diameter (mm) in raw material particles
q: constant As a result of various tests of q in the formula (a) and the production test of the agglomerated minerals, the present inventors found that the uncalcined agglomerated minerals in the range of q of 0.1 to 0.4. It has been found that the strength of is significantly increased.

The large q in the above formula (a) means that the proportion of coarse particles in the raw material is relatively large. When there are many coarse particles, the space | gap between raw material particles becomes large, and contact with raw material particles decreases, and the intensity | strength of an agglomerate falls. Therefore, in order to obtain a predetermined strength, it is necessary to increase the amount of binder between the raw material particles.
However, by adjusting the particle size configuration so that q in the formula (a) is in the range of 0.1 to 0.4 as described above, as schematically shown in FIG. By filling the voids with particles of medium particle size, fine particles between the particles of medium particle size and further fine particles between the particles, the voids as a whole become extremely small and added. It was found that high strength can be obtained even with a small amount of binder.

FIG. 2 shows the results of examining the relationship between q in the above formula (a) and the cold strength of the unfired agglomerated ore. In this test, water is added to a raw material in which iron ore having a particle size of less than 4 mm, iron ore powder having a particle size of less than 0.1 mm, binder (cement) and hematite powder is mixed, granulated by a pelletizer, and then cured for one day. An unfired agglomerated mineral was produced. At that time, q was changed by changing the ratio of iron ore and iron ore powder. The blending amount of the binder was set to two levels of 5 mass% and 10 mass%, and d ₀ and D in the above formula (a) were d ₀ = 0.01 mm and D = 5 mm, respectively.

According to FIG. 2, it can be seen that high cold strength is obtained when q is in the range of 0.1 to 0.4. For this reason, in the present invention, q is set to 0.1 to 0.4, and the cumulative volume fraction P (%) of the raw material having a particle size of d (mm) or more satisfies the following formula (1).
100 × (d / D) ^0.1 ≦ P ≦ 100 × (d / D) ^0.4 (1)
D: Maximum particle diameter in raw material particles (mm)

In the formula (1), d is preferably about 0.001 to 0.2 mm. The reason why d is 0.001 mm or more is that those having a particle diameter of less than 0.001 mm hardly affect the formation of voids in the raw material. If d is too large, particles having a particle size that greatly affects the formation of voids in the raw material will be excluded from the target of the formula (1), which is not preferable. For this reason, d is preferably about 0.001 to 0.2 mm.
The maximum particle diameter D in the raw material particles is preferably about 2 to 5 mm. When D is less than 2 mm, the porosity of the coarse particles is too small, and the strength improvement due to the fine particles is small. On the other hand, when D exceeds 5 mm, the particles become too large, and the strength rapidly decreases.

In order to adjust the raw material particle size of the unfired agglomerated mineral so as to satisfy the above formula (1), for example, the mixing ratio of raw materials having different particle size distributions as shown in FIG. That is, in order to reduce q as a whole particle size distribution, the ratio of raw materials having a particle size distribution as shown in FIG. 3 (a) is increased. Conversely, to increase q, the particle size as shown in FIG. Since the proportion of raw materials having a distribution may be increased, a particle size distribution satisfying the above formula (1) can be obtained by adjusting those proportions.
In addition, when it is desired to adjust a part of the particle size distribution with respect to the target particle size distribution, the raw material having an excessive or insufficient particle size distribution may be added or decreased. That is, for example, when it is desired to increase the submicron particle size, the ratio of the raw material having the particle size distribution as shown in FIG. 3A is increased, or when it is desired to decrease the particle size of several tens of microns as shown in FIG. What is necessary is just to reduce the ratio of the raw material which has a particle size distribution like (c). In addition, as an alternative to these particle size configurations, the raw materials having a particle size distribution as shown in FIG.

The purpose of the present invention is to impart a predetermined strength to the unfired agglomerated mineral with as little binder content as possible, but in the present invention, the amount of binder in the raw material is independent of the type of binder (B). Even if it is 10 mass% or less, sufficient strength (strength corresponding to the type of binder) can be ensured. However, if the binder content is extremely small, sufficient strength cannot be ensured, and therefore the lower limit of the binder content is preferably about 5 mass%.
The particle size of the unfired agglomerated mineral of the present invention (spherical equivalent particle size in a normal temperature atmosphere) is preferably about 8 to 30 mm. If the particle size of the non-fired agglomerated mineral is less than 8 mm, the air permeability of the raw material packed layer when charged in the blast furnace may be deteriorated. On the other hand, if the particle size exceeds 30 mm, the reducibility may be reduced. .

Moreover, you may mix | blend things other than the iron raw material for iron making (A) and a binder (B) as a raw material for the non-baking agglomerated mineral of this invention. For example, in addition to the iron oxide-containing powder (C) described later, an appropriate amount of one or more of various dispersants, hardening accelerators, limestone fine powder, fly ash, silica fine powder, coke powder, and other reducing materials can be blended.
The unfired agglomerated ore of the present invention is used as an iron raw material in a vertical iron furnace represented by a blast furnace.

The non-fired agglomerated ore of the present invention is usually obtained as a solidified product of a granulated product, a solidified product of a molded product, a crushed product of a solidified product (for example, a molded solidified product or an amorphous solidified product), and the like.
In the case of a granulated solidified product, the raw material and water are mixed and stirred (kneaded), then granulated, and the resulting granulated product is cured for a certain period of time, thereby producing a non-fired agglomerated mineral product. Get. The granulation method is arbitrary, but representative methods include a rolling granulation method (pelletizing) using a disk pelletizer or a drum type granulator, a compression granulation method (briquetting) using a briquetting machine, etc. Any of these may be used.

Further, in the case of a solidified product of a molded product, a raw material and water mixed and stirred (kneaded) are poured into a mold, molded, and then cured for a certain period of time to obtain a non-baked agglomerated product. be able to.
Also, in the case of a crushed solidified product, the molded solidified product obtained by the same method as the above molded product or a mixture / stirred mixture of raw material and water is wet sprayed and cured for a certain period of time. The non-fired agglomerated mineral product can be obtained by crushing the amorphous solid body obtained by the above-mentioned method with an appropriate crushing means.

  By the way, when cement or organic matter is used as a binder for unfired agglomerated minerals, cement hydrate is thermally decomposed at high temperature in the furnace, or the organic matter is melted to lower the strength, and powdered in the middle and lower parts of the blast furnace. May occur. In response to such problems, the present inventors have newly added a bonding by sintering in the high temperature region in the furnace if a material to be sintered using the high temperature atmosphere in the furnace is added to the unfired agglomerated mineral. Based on the idea that the high temperature strength is not generated, the following examination was performed.

但し ｒ：粒子半径
ｘ：焼結により生成される接合部の長さ
Ｌ：焼結する２粒子の直径の和
ΔＬ：収縮量
Ｋ：定数
Ｄ：拡散係数
γ：表面エネルギー
ａ：イオン間距離
ｋ：ボルツマン定数
Ｔ：温度
ｔ：焼結時間 Many basic studies have been made on the sintering reaction. For example, Yasuo Arai, Material chemistry of powders, Baifukan (1987), p143 includes the following formulas (2) and (3): Proposed.

Where r: particle radius x: length of the joint produced by sintering L: sum of diameters of two particles to be sintered ΔL: shrinkage K: constant D: diffusion coefficient γ: surface energy a: inter-ion distance k : Boltzmann constant T: Temperature t: Sintering time

The above equation (2) is the one obtained by standardizing the length of the joint produced by sintering with the particle radius, and is formulated with the temperature, the particle radius and the sintering time, and the above equation (3) is The shrinkage rate (ΔL / L) is similarly formulated. The definitions of ΔL and L are shown in FIG.
From the above equation (2), it can be seen that the growth of the joint is larger as the diffusion coefficient D is larger, the sintering time t is longer, and the particle radius r is smaller. Although the diffusion coefficient D varies depending on the material, the diffusion coefficient D increases as the defect concentration of the crystal lattice decreases (there are fewer impurities). Similarly, from the above equation (3), it can be seen that the shrinkage ratio (ΔL / L) by sintering is larger as the diffusion coefficient D is larger, the sintering time t is longer, and the particle radius r is smaller.

From the above, it is estimated that the addition of high-purity fine particles can increase the strength of the non-fired agglomerated minerals at high temperatures by sintering these particles. As a result of repeated studies, it has been found effective to use iron oxide powder having a predetermined particle size or less. In other words, uncalcined agglomerated minerals to which an appropriate amount of iron oxide powder has been added begin to sinter the iron oxide powder from several hundred degrees Celsius at which the bond strength decreases due to a binder such as cement. It was found that interstitial strength could be secured. In addition, the ability to use such an iron-based material (iron oxide powder) is desirable as an agglomerate for iron making.
Such a non-fired agglomerated mineral of the present invention further includes an iron oxide-containing powder (C) in which the ratio of the particle size of 10 μm or less is 90 mass% or more in the raw material (provided that the powder is composed only of iron oxide) .)) Is a non-fired agglomerated mineral for iron making. This non-calcined agglomerated mineral develops strength (hot strength) due to sintering of the added iron oxide-containing powder (C) in a high temperature range in the furnace.

  FIG. 4 shows the basic structure of the unfired agglomerated mineral and the behavior at the time of temperature rise, and x is the unfired agglomerated mineral. As shown in FIG. 4 (a), the basic structure of the unfired agglomerated x is a mixed layer of iron raw material a for iron making and a binder b, and iron oxide-containing powder c (particle size 10 μm) scattered in the mixed layer. The following ratio is comprised of 90 mass% or more iron oxide-containing powder). When such a non-fired agglomerated x is charged in a blast furnace and heated, the iron oxide-containing powder c begins to sinter when the temperature exceeds approximately 500 ° C., and FIG. As shown in FIG. 4, the sintered iron oxide-containing powder c becomes a non-fired agglomerated x ′ that exhibits a binder function while reducing the diameter.

  FIG. 5 schematically shows the sintering behavior of the particles of the iron oxide-containing powder c. When particles come into contact with each other in a high-temperature atmosphere, the material diffuses and moves at the interface and bonds. For this reaction, the equations (2) and (3) listed above are followed. In the case of the unfired agglomerated x, as shown in FIG. 6, contact / joining between the iron oxide-containing powder c and the iron raw material a for iron making may be considered. In general, the iron raw material a for iron making contains various impurities in iron oxide, and its particle size is often in the order of millimeters. For this reason, the sintering rate is slow as shown in the above equation (2). Therefore, diffusion from the iron-making iron raw material a to the iron oxide-containing powder c is slow, but diffusion from the iron oxide-containing powder c to the iron-making iron raw material a is fast. As a result, the iron oxide-containing powder c serves as a “paste” for joining the iron raw material a for iron making.

The iron oxide-containing powder (C) contains iron oxide and is not specifically limited as long as it contains 90 mass% or more of powder having a particle size of 10 μm or less. Also good. Further, when the iron oxide-containing powder (C) contains a substance other than iron oxide (for example, SiO ₂ , Al ₂ O _3, etc.), the substance may be contained as part of the particles together with the iron oxide. However, it may be contained as particles not containing iron oxide. The iron oxide is not limited to Fe ₂ O ₃ (hematite), but may be Fe ₃ O ₄ (magnetite) or FeO.
In addition, as a measuring method of the particle size of this iron oxide containing powder (C), the measuring method using a laser diffraction type particle size distribution measuring apparatus is applicable, for example. This measurement method utilizes the fact that when a particle is irradiated with a laser beam, the intensity and distribution of the diffracted / scattered light depends on the particle size distribution of the particle, and the particle size distribution can be measured with extremely high accuracy. .

In order to determine the particle size of the iron oxide-containing powder effective for sintering as shown in FIG. 6, a basic test as shown below was conducted. The iron oxide powder (Fe ₂ O ₃ ) adjusted to a very narrow particle size distribution as shown in FIG. 7 was formed into a tablet shape, and the shrinkage ratio after firing in an electric furnace was measured. The particle size of the iron oxide powder is 99.3 mass% at 6.5 μm or less and 16.1 mass% at 5.5 μm or less, and this was represented by 6 μm. Since the decomposition of cement hydrate begins in the blast furnace and the strength of the conventional cement bond-type non-fired agglomerated ore starts to decrease, the temperature is in the range of 500 to 700 ° C. The sintering reaction was carried out in a blast furnace with a firing time of 1 hour in consideration of a residence time of 500 to 700 ° C. Since the shrinkage (ΔL / L) at this time was 0.0715, the unknown in the above equation (3) was determined, and the relationship between the particle size and the shrinkage was determined and shown in FIG. From the figure, the maximum particle size that shrinks at 700 ° C. was determined by drawing. The two straight lines (broken lines) shown in the figure are virtual extensions of the “parts close to a straight line” of the curve where the particle size is small and large, and shrinkage starts at 700 ° C. at the intersection of these. When the maximum particle size is obtained, the maximum particle size that shrinks is estimated to be 10 μm, and particles smaller than this particle size are estimated to contribute to shrinkage, that is, sintering. For the reasons described above, the iron oxide-containing powder (C) preferably has a particle size of 10 μm or less. Therefore, in the present invention, the iron oxide-containing powder (C) having a particle size of 10 μm or less is 90 mass% or more.

Examples of the iron oxide-containing powder (C) having a particle size of 10 μm or less of 90 mass% or more include steel pickling line recovered powder (so-called Rusner iron oxide, etc.), refined dust generated in the steel manufacturing process, iron ore fine powder, and the like. One or more of these can be used.
Here, the steel material pickling line recovered powder is as follows. In the cold rolling step of a steel material manufacturing process such as a steel plate, the surface iron oxide layer is removed by pickling (pickling with a hydrochloric acid solution) before rolling. In this pickling solution, iron is eluted as iron chloride. By treating this iron chloride by a method such as roasting, high purity and fine iron oxide powder (hematite powder) is recovered. This iron oxide powder is very fine (usually iron oxide content: 95 mass% or more) and fine powder, and is suitable as iron oxide-containing powder (C).

Further, the refining dust generated in the steel production process includes refining dust generated in the hot metal pretreatment process, refining dust (converter OG dust) generated in the converter decarburization process, and the like. These refining dusts are collected by collecting dust from the exhaust gas generated in the refining process. These dusts are high in content of iron oxide powder and fine powder, and are suitable as iron oxide-containing powder (C).
The content of the iron oxide-containing powder (C) in the unfired agglomerated mineral is preferably 1 to 30 mass%, particularly 5 to 30 mass%, in terms of iron oxide. If the content of the iron oxide-containing powder (C) is less than 1 mass% in terms of iron oxide, the binder action due to sintering of the iron oxide-containing powder (C) is not sufficient, while if it exceeds 30 mass%, the iron for iron making Productivity decreases because the amount of the raw material (A) decreases.

In FIG. 10, an example of the manufacturing flow of the non-baking agglomerated mineral of this invention is shown. This production flow shows a case where an unfired agglomerated ore is produced using an iron raw material for iron making (A), a binder (B) and an iron oxide-containing powder (C) as raw materials.
In the figure, 1a to 1c are raw material storage tanks storing iron raw materials (A), binders (B), and iron oxide-containing powders (C), respectively, and quantitative cut-out devices from these raw material storage tanks 1a to 1c, etc. Is used to cut out a predetermined amount of iron raw material (A) for iron making, binder (B) and iron oxide-containing powder (C), and to the humidifying mixer 3 (for example, a drum mixer, an Eirich mixer, etc.) by the raw material conveying device 2 Introduce. Note that the iron raw material for iron making (A), the binder (B), and the iron oxide-containing powder (C) may be mixed in advance and cut out from one raw material storage tank. Although not shown, there may be a pulverization step for adjusting the particle size in advance, a step for removing foreign matter, and the like as necessary.

In the humidifying mixer 3, water is added to the raw material and mixed and stirred. Although there is no special restriction | limiting in the function of the humidification mixer 3, etc., a thing with high mixing stirring ability is desirable. In the case where a material having a low mixing and stirring ability is adopted, it is necessary to take a long mixing time, and productivity is lowered.
The raw material humidified and mixed by the humidifying mixer 3 is transferred to the granulator 5 by the raw material conveying device 4 and granulated here. In FIG. 10, a dish-type rolling granulator (disk pelletizer) is used as the granulator 5, but as described above, other types of granulators may be used.

When a dish-type rolling granulator as shown in FIG. 10 is used, an agglomerate (granulated material) close to a spherical shape is produced. On the other hand, when a compression granulator is used, various shapes such as an almond shape and a bean charcoal shape can be manufactured depending on the type used. However, as described above, any shape may be used as long as the spherical equivalent particle diameter in a normal temperature atmosphere is about 8 to 30 mm.
The granulated product (agglomerated product) obtained by the granulator 5 is conveyed to the stationary yard 7 by the raw material conveying device 6 and is cured in the stationary yard 7 for a predetermined time, so that it can be used in the blast furnace. It becomes a calcined agglomerated x.

FIG. 10 shows a raw material obtained by adding Portland cement as a binder (B) and hematite powder as an iron oxide-containing powder (C) to iron ore (iron ore powder) as an iron raw material (A) for iron making. Granulation using a simple production flow and curing for a certain period of time to produce a non-fired agglomerated ore. Here, steel material pickling line collection powder was used as hematite powder.
The component composition of the raw materials used is shown in Table 1, and the particle size distribution is shown in FIG. The components of iron ore (1) and (2) are the same, but iron ore (1) has a slightly fine particle size and a particle size of 20 μm or less is 10 mass% or less. On the other hand, the iron ore (2) has a slightly coarse particle size and a particle size of 40 μm or less is 10 mass% or less.
Further, the hematite powder (1) has a very high iron oxide content and is fine, and the ratio of the particle size of 10 μm or less is 90 mass% or more. On the other hand, the hematite powder (2) has almost the same particle size distribution as the hematite powder (1), but the iron oxide content is low, while the hematite powder (3) has a very high iron oxide content, The particle size is coarse and the ratio of the particle size exceeding 10 μm is close to 40 mass%.

About the raw material of each Example (invention example, comparative example), as shown in FIG. 12, a curve x of a particle size distribution having a particle diameter on the horizontal axis and a cumulative mass ratio on the vertical axis is obtained. In the range, when the minimum value and the maximum value of q were selected so that each curve x was surrounded by two curves of the following formula (a), the minimum q was set to q1, and the maximum q was set to q2.
P (%) = 100 × (d ₀ / D) ^q (a)
Therefore, when q1 and q2 are in the range of 0.1 to 0.4, the above expression (1) defined by the present invention is satisfied.

The unfired agglomerated ore of each example was charged into a blast furnace together with other iron raw materials, and the changes in the cold strength and blast furnace operating status of the unfired agglomerated ore were investigated. The results are shown in Table 2 together with the particle size distribution of the raw materials and the binder blending amount. In addition, the mixture ratio of the iron raw material to a blast furnace was made into non-baking agglomerated mineral: 12 mass%, sintered ore: 79 mass%, lump ore: 9 mass%.
About the cold intensity | strength of a non-baking agglomerated ore, the powder rate in a yard and the powder rate in a blast furnace top were measured, and the difference (powdering rate at the time of transport) evaluated. If the agglomerate has a particle size of 5 mm or more, it can be used as a raw material for a blast furnace. Therefore, particles of −5 mm (= particle size less than 5 mm) are defined as powder, and the mass ratio is set to a powder rate of −5 mm. .

  Also, the “blow-out phenomenon” of the number of blow-throughs shown in Table 2 means that the flow of reducing gas is stopped by increasing the pressure loss in the blast furnace, the pressure in the furnace rises, and reaches a certain pressure. When this happens, it means a phenomenon in which the rising of the reducing gas explosively resumes. In this case, since the charge in the furnace moves with the gas simultaneously with the resumption of the gas flow, the distribution of the charge deposited in layers is disturbed. If the distribution of the charge is disturbed, the air permeability is further deteriorated, and problems such as poor reduction of iron oxide are caused. There is also concern about thermal adverse effects on various facilities due to mechanical damage to the furnace body due to the rise and rapid hot gas ejection.

  According to Table 2, it can be seen that the non-calcined agglomerated mineral of the present invention example has an extremely small amount of powder during conveyance to the blast furnace as compared with the non-calcined agglomerated mineral of the comparative example. In addition, when looking at the operation of the blast furnace, the amount of dredging is large, the ratio of reducing material is low, and there is no blow-through phenomenon. From these results, it can be seen that the non-fired agglomerated mineral ore of the present invention can significantly improve the blast furnace operation compared to the comparative example having the same binder amount, and is still superior even when the binder amount is reduced. .

Explanatory drawing which shows typically the filling state of the raw material of the non-baking agglomerated mineral of this invention (A) A graph showing the relationship between q in the formula and the cold strength of the unfired agglomerated ore Explanatory drawing showing the particle size distribution of the raw material used to adjust the raw material particle size of the agglomerated mineral so as to satisfy equation (1) Explanatory drawing which shows the basic structure of the non-baking agglomerated mineral of the present invention in which the iron oxide-containing powder (C) is blended and the behavior at elevated temperature Explanatory drawing which shows typically the sintering behavior of the particle | grains of the iron oxide containing powder in the non-baking agglomerated mineral of this invention mix | blended with the iron oxide containing powder (C). Explanatory drawing which shows typically the contact and joining state of the iron oxide containing powder and the iron raw material for iron making in the non-baking agglomerated mineral of the present invention in which the iron oxide containing powder (C) is blended Graph showing the particle size distribution of iron oxide powder used in the basic test Graph showing the relationship between the particle size of iron oxide powder used in the basic test and the shrinkage ratio of tablets due to iron oxide powder Explanatory drawing which shows the definition of ΔL and L of shrinkage rate (ΔL / L) by sintering of particles Explanatory drawing which shows an example of a manufacturing flow of the non-baking agglomerated mineral of this invention Graph showing the particle size distribution of the raw materials used in the examples The graph which showed how to obtain q1 and q2 of each raw material blend in the examples

Explanation of symbols

x, x 'Non-calcined agglomerates a Iron raw material for iron making b Binder c Iron oxide-containing powder 1a to 1c Raw material storage tank 2, 4, 6 Raw material transfer device 3 Humidification mixer 5 Granulator 7 Standing yard

Claims (7)

A non-fired agglomerated mineral obtained by solidifying a raw material in which the binder (B) is blended with the iron raw material (A) for iron making,
A non-fired agglomerated ore for iron making, wherein a cumulative volume fraction P (%) of a raw material having a particle size of d (mm) or more satisfies the following formula (1):
100 × (d / D) ^0.1 ≦ P ≦ 100 × (d / D) ^0.4 (1)
D: Maximum particle diameter in raw material particles (mm)   The uncalcined agglomerated mineral for iron making according to claim 1, wherein d is 0.001 to 0.2 mm and D is 2 to 5 mm.   The uncalcined agglomerate for iron making according to claim 1 or 2, wherein the blending amount of the binder (B) in the raw material is 10 mass% or less.   The agglomerated ore is any one of a solidified product of a granulated product, a solidified product of a molded product, and a crushed product of the solidified product. .   The non-fired agglomerated mineral for iron making according to any one of claims 1 to 4, wherein the iron raw material (A) for iron making is a fine grain sintered ore and / or fine grain iron ore.   An iron oxide-containing powder (C) having a particle size of 10 µm or less in a raw material of 90 mass% or more (including a case where the powder is composed only of iron oxide) is further blended in the raw material. The non-baking agglomerate for iron manufacture in any one of 1-5.   The uncalcined agglomerate for iron making according to claim 6, wherein the blending amount of the iron oxide-containing powder (C) in the raw material is 1 to 30 mass% in terms of iron oxide.

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