JP6508500B2 - Method of producing sintered ore - Google Patents

Description

  The present invention relates to a method for producing sintered ore as a blast furnace raw material used in a Dwight-Lloyd type sintering machine or the like.

  Sinter is a multi-grade powdered iron ore (generally called Sinter feed of about 125 to 1000 μm), secondary raw material powder such as limestone, silica stone, serpentine, etc., dust, scale, return mineral, etc. Water is added to the sinter compounding raw material mixed with appropriate amounts of miscellaneous raw material powder and solid fuel such as powdered coke, mixed and granulated, and the obtained granulated raw material is charged into a sintering machine Manufactured by firing. In general, the sinter compounding raw materials aggregate with one another at the time of granulation due to the inclusion of water to form pseudo particles. And, this pseudogranulated sintering raw material for sintering, when being loaded on the pallet of the sintering machine, helps to ensure good ventilation of the sintering raw material charge layer, and makes the sintering reaction smooth. Advance to During the sintering reaction, the moisture of the heated granulated particles evaporates, and the granulated particles in the leeward become high moisture to form a region in which the strength decreases (wet zone). This wet zone tends to crush the granulated particles, blocking the flow path of the air in the packed bed and deteriorating the aeration.

  On the other hand, in recent years, pulverization of iron ore has progressed, and the granulated particles using this fine ore have a reduced strength. In particular, when water is added, the strength is greatly reduced, which causes a reduction in ventilation. Fine ore is also known to be difficult to granulate which is important in the production of sintered ore. In such an environment surrounding powdered iron ore for sintering, recently, a technology has been proposed for producing high-quality sintered ore using iron ore containing a large amount of fine powder which is hard to be granulated. There is.

  Conventionally, the following techniques are known as a manufacturing method of the sintered ore as such blast furnace materials (patent documents 1-9).

Japanese Patent Application Laid-Open No. 62-37325 Unexamined-Japanese-Patent No. 1-312036 gazette JP 2007-247020 A Japanese Patent Application Laid-Open No. 11-61282 Japanese Patent Laid-Open No. 7-331342 Japanese Patent Application Laid-Open No. 7-48634 JP, 2005-194616, A Unexamined-Japanese-Patent No. 2006-63350 Unexamined-Japanese-Patent No. 2003-129139

  Patent Document 1 discloses a Hybrid Pelletized Sinter method (hereinafter referred to as "HPS method"). This technology is intended to produce a low slag ratio and high reducibility sintered ore by granulating a sinter compounding material containing a large amount of fine iron ore with high iron content using a drum mixer and a pelletizer. It is. However, in this technology, when processing a large amount of sintering raw material, it is necessary to install many pelletizers, and there is a problem that manufacturing cost becomes large.

  Also, before the granulation step, a method of mixing finely powdered iron ore and iron making dust in advance with a stirring mixer, and further granulating with a stirring mixer, or after stirring a sintering raw material mainly composed of fine powder with a stirrer The method of granulating using a granulator is proposed (patent documents 2-3). However, in these methods, granulated particles are mainly composed of fine powder material, and there is a problem that the strength of the granulated particles is reduced as compared with the case where core particles (iron ore) having higher strength than granulated particles are included.

  Furthermore, there are proposals such as methods (Patent Documents 4 to 6) in which sintering raw materials in which fine powder and sinter feed are mixed are mixed in advance with an Eirich mixer and then granulated with a drum mixer. However, in these methods, when the fine powder ratio increases, the attached powder layer becomes excessive, and the combustion property deterioration of the granulated particles is a problem. In addition, there is a problem that the granulation property is deteriorated due to the shortage of the core particles, and the baking is performed while the granulation is incomplete.

  Furthermore, the report (patent documents 7-9) which processes the non-granulation ore which contains fine powder and contains many crystal waters is proposed. However, in these methods, during sintering, it is difficult to prevent the rise in pressure loss in the wet zone due to the evaporation of a large amount of water from the high-crystal ore. Moreover, when using many fine iron ores in which the strength of granulated particles tends to decrease, there is also a problem that the pressure loss in the wet zone tends to increase.

  The present invention has been made focusing on the above problems, and it is possible to produce granulated particles of high strength even using iron ore containing a large amount of fine powder which is difficult to granulate. It is an object of the present invention to propose a method of producing sintered ore which can obtain high quality sintered ore.

  The present applicants have a method of improving the strength of granulated particles when using fine iron ore, a method of reducing evaporation of crystal water to suppress pressure loss increase in the wet zone, and low crystal water And when using the ore containing many fine powders, the method of efficiently granulating was examined, and the following inventions were achieved.

  That is, the present invention comprises a sintered material comprising iron ore containing 20 mass% or more of core particles having a particle diameter of 1 mm or more and 10 to 50 mass% of fine powder having a particle diameter of 0.125 mm or less It is a method of producing sintered ore characterized by granulation after stirring using a high speed stirrer and subsequent firing.

In the method of producing sintered ore according to the present invention,
(1) Stirring and granulating a sintered raw material containing iron ore containing 25 to 40 mass% of fine powder having a particle size of 0.125 mm or less
(2) Crystal water is 4 mass% or less,
(3) To make the peripheral speed of the stirring blade of the high speed stirrer 6 m / s or more,
(4) Water content of 6 mass% or less when pretreated with a high-speed stirrer,
Is considered to be a more preferable solution.

  According to the present invention, by containing a large amount of core particles, high quality sinter can be produced even when using iron ore containing a large amount of fine powder which is difficult to granulate, and sinter ore. It is possible to improve the production rate.

It is a figure for demonstrating an example of the equipment row | line | column which implements the manufacturing method of the sintered ore of this invention. When changing a fine powder ratio, it is a graph for comparing the sintering production rate with the case where it does not carry out at the time of performing high-speed stirring. It is a graph which shows the relationship between a core particle ratio and a sintering production rate. It is a graph which shows the relationship between the circumferential speed of the stirring blade of a high speed stirrer, and a harmonic mean diameter. It is a graph which shows the relationship between the water at the time of stirring, and the ratio of particle size 4.75 mm or more.

  FIG. 1 is a figure for demonstrating an example of the equipment row | line | column which implements the manufacturing method of the sintered ore of this invention. The method for producing the sintered ore according to the present invention will be described according to FIG. 1. First, an iron ore containing 20% by mass or more of core particles having a particle diameter of 1 mm or more and 10 to 50 mass% of fine powder having a particle diameter of 0.125 mm or less , The sintering raw material 11 comprised from an auxiliary raw material is prepared. The sintering material 11 contains iron ore containing 30 mass% or more of core particles having a particle diameter of 1 mm or more and 10 to 50 mass% of fine powder having a particle diameter of 0.125 mm or less, a coagulating material such as powdered coke, return ore, It is preferable to consist of secondary raw materials such as silica stone, lime and quick lime.

  Next, pre-treatment of the prepared sintering material 11 is performed by the high speed stirrer 12. The purpose of the high-speed stirrer 12 is to break up agglomerates of fine powder, which become seeds of coarse granulated particles, before granulation in order to suppress the formation of coarse granulated particles. Microscopically, it is effective to apply shear force to the aggregate itself to directly exfoliate the fine powder in order to efficiently break up the fine powder aggregate. As an example of the high-speed stirrer 12, for example, an Eirich mixer, a Peregeria mixer, a Proshare mixer, etc. can be used. Among these, the Eirich mixer is known as a "high-speed stirring granulator", and is a facility having a granulating function associated with aggregation and growth of particles by liquid crosslinking.

  Next, the sintering raw material 11 which performed pre-processing with the high-speed stirrer 12 is stirred and mixed by the drum mixer 13 under moisture addition, and it granulates. The sintered raw material 11 after granulation is supplied to the sintering machine 14 and becomes sintered ore in the sintering machine 14. Then, the sintered ore is supplied to the blast furnace 15 as a blast furnace raw material together with coke, limestone and the like to produce pig iron.

  In the equipment row shown in FIG. 1, after granulation with a drum mixer, granulated particles are directly charged into a sintering machine and fired. However, the equipment row as described below for the configuration up to the sintering machine You can also take That is, (1) an agitator, a drum mixer, a drum mixer, and an installation row for arranging a plurality of drum mixers, and (2) arranging a pelletizer between the agitator, the drum mixer, the pelletizer, the drum mixer and the plurality of drum mixers Equipment row, (3) In the present invention, low crystal water ore was used to reduce pressure loss in the wet zone, but in order to further suppress the formation of the wet zone, the drying process after granulation by the drum mixer The present invention can also be suitably applied to equipment rows in which the

  The production of the sintered ore of the present invention is carried out according to the above-mentioned equipment row, and the feature of the method for producing sintered ore of the present invention is that the material contains 20 mass% or more of core particles having a particle diameter of 1 mm or more There is a point of using iron ore containing 10 to 50 mass% of fine powder having a diameter of 0.125 mm or less, and a point of performing stirring by a high-speed stirrer as a pretreatment before granulation.

  First, in the method for producing a sintered ore according to the present invention, core particles containing at least 20 mass% of core particles having a particle diameter of 1 mm or more in iron ore are contained in the iron ore. Therefore, granulation is promoted compared to the case where the number of core particles is small. Since granulated particles containing a large amount of fine powder have low strength, it is important to suppress the destruction of the granulated particles against pressure in order to increase the strength. Therefore, reducing the easily breakable part in the granulated particles leads to an increase in particle strength by having the core particles having a strength higher than that of the fine powder aggregate.

  Here, the reason for limitation to core particles having a particle size of 1 mm or more is that core particles are generally 1 mm or more. Moreover, the reason for limiting the core particle to 20 mass% or more is because the sintering production rate is deteriorated when the core particle is less than 20 mass% from the result of Example 2 below. Furthermore, it is preferable to set it as 30 mass% or more. The upper limit is not particularly set, but is preferably 80 mass% or less.

  Moreover, in the method for producing sintered ore according to the present invention, although the fine powder having a particle size of 0.125 mm or less is contained in 10 to 50 mass% iron ore, the raw material containing a large amount of fine powder has strength due to the deviation of water. It is easy to form granulated particles of only fine powder of By using a high-speed stirrer, these particles are broken down to break up the aggregation of fine powder and the raw material is uniformly dispersed. By doing so, aggregation of the fine powder is eliminated and the adhered powder layer is reduced, so that granulated particles of high strength can be produced.

  Here, the reason why fine powder with a particle size of 0.125 mm or less is contained in 10 to 50 mass% iron ore is that pseudo particles with weak bonding strength can not be produced if it is less than 10%. Similarly, there is a problem that coarse particles with weak bonding strength can be formed, but the content is not more than 50 mass% of substantially 125 μm or less pulverized iron ore, and the upper limit is 50%. The particle size of 125 μm or less shows that the particle size of 125 μm or less shows largely different behavior of granulation because adhesion showing the adhesion between particle layers in the powder filled layer to which water is added is increased. It is because

  Furthermore, in the method for producing sintered ore according to the present invention, crushing with a high-speed stirrer requires a sufficient force to break up the agglomeration of fine powder, and the circumferential speed of the stirring blade has been proposed so far. By applying a large force, it is possible to break up the aggregation of the fine powder. In addition, the aggregation of the fine powder is already high when the water content of the sintering raw material reaches the granulated water content. Therefore, by stirring the raw material in a low water state before adding water, the crushing effect of the agglomerate of fine powder is further promoted.

  Furthermore, in the preferred embodiment of the method for producing sintered ore according to the present invention, the raw material is sintered using an ore having a small amount of crystal water causing the wet zone in order to suppress the wet zone causing the reduction of production when using fine powder We propose a method of granulating and producing sinter. According to this method, as described above, in the granulated particles obtained, the generation of moisture when the temperature becomes high in the sintering machine is reduced as compared with the case of using high-crystal water ore. When the moisture in the wet zone is reduced, the pressure loss of the wet zone is reduced to improve the ventilation in the sintering material (sinter bed) during sintering. As a result, it is possible to improve the sinter production rate. Further, by suppressing the evaporation of water, there is also an effect that the coagulating material which is the fuel can be reduced.

  As mentioned above, although the present invention has been described with reference to the embodiment, after high speed stirring of the present invention, the whole amount of granulated particles granulated can be used as a sintering raw material, and the high speed stirring of the present invention After that, mixing the granulated particles granulated and the granulated particles granulated without high-speed stirring and applying them to the sintering raw material is also included in the scope of the present invention. Furthermore, the present invention is not limited to the configuration described in the above-described embodiment, but also includes other embodiments and modifications which can be considered within the scope of matters described in the claims. .

Next, an example carried out to confirm the effect of the present invention will be described.
In the present invention, the core particle ratio is defined as the weight ratio of particles having a particle diameter of 1 mm or more, and the fine powder ratio as particles having a particle diameter of 0.125 mm or less in iron ore. Here, in the measurement method, the collected iron ore is dried, sieved using a mesh sieve of JIS Z 8801, the weight of each particle size is measured, and the weight ratio of each particle size is calculated from the weight of the entire iron ore. Further, the water content of the sintering material is a value obtained by dividing the weight of water in the sintering material by the weight of the sintering material containing water, and in the present invention, from the weight of the dried sintering material and the added water It is a calculated value. Here, the sintering raw material used the iron ore containing the said core particle and fine powder, and the thing containing a coagulating agent and an auxiliary raw material. However, in general, sintering materials are powder iron ore of multiple brands, auxiliary materials such as limestone, silica, serpentine, dusts, scales, miscellaneous materials such as returned ore, binders such as quick lime, coke, etc. An appropriate amount of coagulating material as solid fuel is blended.

<Example 1: About the influence of high-speed stirring and a fine powder ratio>
In the test, the core particles having a particle diameter of 1 mm or more are 30 mass% or more, the crystal water is 4 mass% or less, the fine powder ratio is 10 mass% (core particles: 42 mass%, crystal water: 4 mass%), 25 mass% (core particles: 40 mass) %, Crystal water: 3 mass%), and 40 mass% (core particles: 36 mass%, crystal water: 3 mass%) were used. Here, the water of crystallization of the sample is an average value determined by weighted average from the weight ratio of each water of crystallization of the blended iron ore. In the present invention, the crystal water of iron ore blended is obtained by the calculation method of the average value. The measurement of the crystal water of each ore was performed according to JIS M 8700. 69 to 70 mass% of these iron ores, 16 mass% of returned ore, 14 mass% of limestone and 0 to 1 mass% of silica stone are compounded internally, and 5% of powdered coke which is a coagulating material is externally added. Water was added thereto so that the water content of the sintering raw material was 6 mass%.

These samples were tested with and without pre-treatment with a high speed stirrer. The high-speed stirrer uses an Eirich mixer, the length of the stirring blade is 350 mm in diameter, and the container is 750 mm in diameter. The circumferential velocity v (m / s) of the stirring blade is determined by the number of revolutions N (rpm) of the stirring blade and the length 350 mm of the stirring blade.
ν = 0.35 × π × N / 60
And In the present invention, the peripheral speed was stirred at 6 m / s for 60 seconds.

Thereafter, granulation was performed for 5 minutes using a drum mixer while adding water so as to be 7 mass% of water with respect to these sintering materials, and baking was performed using a pan tester. When the sinter cake after sintering is dropped once from a height of 2 m, a product with a particle size of +10 mm is a product, and the value obtained by dividing the weight by (sinter cake weight-bed bed weight) is the yield did. The sintered production rate (t / (m ² · h)) was obtained by dividing the product weight by the baking time and the cross-sectional area of the test pan.

  The measurement results are shown in FIG. As shown in FIG. 2, it was found that when the fine powder ratio increases more than 10 mass% or more, which is a normal fine powder ratio, the sintering production rate decreases in the case of the drum mixer alone. On the other hand, it was found that although the sintering production rate decreases with the increase of the fine powder when pre-treatment by high-speed stirring is performed, the decrease is suppressed remarkably as compared with the case of granulation using only the drum mixer.

<Example 2: Regarding the influence of the nuclear particle ratio>
An experiment was conducted in which the ratio of core particles was changed using iron ore having a crystal water content of 4 mass% or less and a fine powder ratio of a particle diameter of 0.125 mm or less of 40 mass%. The experiment was carried out in the range of 13 mass% (crystal water: 2 mass%), 25 mass% (crystal water: 2 mass%), 32 mass% (crystal water: 2 mass%), and 43 mass% (crystal water: 4 mass%) The 69 to 70 mass% of these iron ores, 16 mass% of returned ore, 14 mass% of limestone and 0 to 1 mass% of silica stone are compounded internally, and 5% of powdered coke which is a coagulating material is externally added. Water was added thereto so that the water content of the sintering raw material was 6 mass%. These samples were stirred by a high speed stirrer. In the high speed stirrer, the length of the stirring blade is 350 mm in diameter, and the container is 750 mm in diameter. In the present invention, the peripheral speed was stirred at 6 m / s for 60 seconds. Thereafter, granulation was performed for 5 minutes using a drum mixer while adding water so as to be 7 mass% of water with respect to these sintering materials, and baking was performed using a pan tester.

  The measurement results are shown in FIG. As shown in FIG. 3, it was found that the sintering production rate is improved at 20 mass% or more of the core particles, but particularly when 30 mass% or more is used, the sintering production rate is remarkably improved. It is thought that this is because the inclusion of the core particles increases the strength of the granulated particles and that the mixing of many cores with the sintering material promotes granulation and improves aeration during sintering. Be

<Example 3: Preferred circumferential speed of the stirring blade of the high speed stirrer>
Next, the suitable circumferential speed at the time of processing the sintering raw material using iron ore with little crystal water, a high fine powder ratio, and a high core particle ratio by high speed stirring was examined. As the conditions of the sample, iron ore having 2 mass% of crystal water, 25 mass% of fine powder ratio, and 30 mass% of core particles is used. 70 mass% of this iron ore, 16 mass% of returned ore, and 14 mass% of limestone were compounded internally, and 5 mass% of powdered coke which is a coagulating material was externally added. Water was added thereto so that the water content of the sintering raw material was 6 mass%.

  The sample was stirred for 60 seconds with a high speed stirrer. In the high speed stirrer, the length of the stirring blade is 350 mm in diameter, and the container is 750 mm in diameter. In the present invention, the peripheral speed was changed at 0 to 12 m / s. Thereafter, granulation was carried out for 5 minutes using a drum mixer while adding water to these sintered materials so that the water content became 7 mass%. In the present embodiment, the harmonic mean diameter of the particles after granulation was evaluated. The harmonic mean diameter is an index generally used to evaluate the ventilation of the powder layer, and the larger the harmonic mean diameter, the more the granulation progresses and the better ventilation.

ここで、ｗ_ｉは各粒経間で得られた重量割合であり、ｘ_ｉは各粒径間の代表粒子径である。各粒径間の代表粒子径は、それぞれ大きいほうの目開きと小さいほうの目開きの相乗平均を用いて、０．２５ｍｍ以下の粒子については０．１２５ｍｍ、８ｍｍ以上の粒子については８ｍｍと、採取された粒子の中の最大の粒子径との相乗平均とした。As for the harmonic mean diameter, 1 kg of the powder sample after agitation processing is collected, and after drying, it has a wide opening with a sieve of 0.25, 0.5, 1, 2.8, 4.75, 8 mm. The said powder sample was sieved in order, and the weight ratio of each particle size was measured. The harmonic mean diameter was determined by the following equation (1).

Here, w _i is a weight ratio obtained between each particle diameter, and x _i is a representative particle diameter between each particle diameter. The representative particle size between each particle size is 0.125 mm for particles of 0.25 mm or less, and 8 mm for particles of 8 mm or more, using the geometric mean of the larger opening and the smaller opening respectively. The geometric mean was taken with the largest particle size among the collected particles.

  FIG. 4 shows the harmonic mean diameter of the formed particles after granulation with a drum mixer. As a result, it was found that the harmonic mean diameter increases with the increase of the peripheral speed until the peripheral speed becomes 6 m / s. When the circumferential speed is 6 m / s or more, the harmonic mean diameter becomes constant. The reason why the harmonic mean diameter increases with the increase in circumferential speed is that when the circumferential speed is low, the dispersion of the water in the sintering material by the stirring blade is insufficient when stirring, and the water does not spread, It is because the particle which is not granulated remains. In addition, when the circumferential speed was sufficiently large, the dispersion of the water was sufficient, the number of non-granulated particles decreased, and the harmonic mean diameter increased.

<Example 4: About the influence of the water content before stirring>
Next, preferred water content before stirring when processing a sintered material using an ore having a small amount of crystal water, a high fine powder ratio and a high core particle ratio by high speed stirring was examined. As the conditions of the sample, iron ore having 2 mass% of crystal water, 25 mass% of fine powder ratio, and 30 mass% of core particles is used. 70 mass% of this iron ore, 16 mass% of returned ore, and 14 mass% of limestone were compounded internally, and 5 mass% of powdered coke which is a coagulating material was externally added. Water was added thereto so that the water content of the sintering raw material was 0 to 7 mass%. Thereafter, granulation was carried out for 5 minutes using a drum mixer while adding water to these sintered materials so that the water content became 7 mass%.

  In the present test, in order to investigate the moisture that facilitates the disintegration of the fine powder aggregate by stirring, the ratio of particles of 4.75 mm or more, which are large particles, was evaluated among the particles after stirring. Usually, granulated particles are a process of producing particles of 3 to 5 mm, and before granulation, particles having a particle diameter of 4.75 mm or more form coarse particles after granulation, and these coarse particles are subjected to It causes the deterioration of combustibility. Therefore, as particles after agitation, it is desirable to reduce particles having a particle diameter of 4.75 mm or more. In addition, the reduction of particles having a particle diameter of 4.75 mm or more means that the fine powder adhering to the core particles is broken up. Therefore, the dispersion of the fine powder progresses, and the raw material becomes an index to be uniformly dispersed and mixed.

  FIG. 5 shows the water content at the time of stirring and the ratio of particles having a particle size of 4.75 mm or more after stirring. As a result, it was found that the proportion of particles having a particle size of 4.75 mm or more after stirring can be reduced by reducing the water content. In particular, it was found that when the water content was 6 mass% or less, the proportion of particles having a particle diameter of 4.75 mm or more was constant. This is because the reduction of the water content also reduced the water content of the fine powder aggregates in the sintering material. By reducing the water content of the fine powder aggregate, the adhesion between the particles necessary for aggregation was reduced, and the disintegration of the aggregate by the stirring blade proceeded.

Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the configuration described in the above-described embodiment, and the items described in the appended claims It also includes other embodiments and modifications that are considered within the scope. For example, it is also included in the scope of the present invention when combining the kneading method of the fine powder raw material of the present invention combining a part or all of each above-mentioned embodiment and modification.

  According to the method of producing sintered ore of the present invention, by containing a large amount of core particles, it is possible to produce high quality sintered ore even when using iron ore containing a large amount of fine powder which is difficult to granulate. As a result, the production rate of sintered ore can be improved, and the present invention can be suitably used in various methods for producing sintered ore.

11 Sintered raw material 12 High speed agitator 13 Drum mixer 14 Sintering machine 15 Blast furnace

Claims (3)

Wherein a particle diameter 1mm or more core particles above 20 mass%, the formed sintered material the following fines particle diameter 0.125mm from 10～50Mass% including iron ore and condensed materials and auxiliary materials, stirring blades of high-speed stirrer A method of producing a sintered ore characterized in that the peripheral speed is 6 m / s or more, the water content is 6 mass% or less, the mixture is stirred using a high-speed stirrer and then granulated and then fired.   The method for producing sintered ore according to claim 1, wherein the sintering raw material containing iron ore containing 25 to 40 mass% of fine powder with a particle size of 0.125 mm or less is stirred and granulated. The process for producing sinter ore according to claim 1 or 2, wherein the crystal water of iron ore is 4 mass% or less.

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