JP2014234545A - Method of manufacturing granulation raw material for sintering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology preventing production of coarse pseudo-particle with uneven particle size and weak bond strength in a granulation raw material for sintering, and granulating pseudo-particle having uniform size.SOLUTION: In a method of manufacturing granulation raw material for sintering through a mixture step of adding moisture to blended raw material containing iron ore hard to be granulated and mixing the resultant material in a drum mixer and a granulation step of granulating the blended raw material after the mixture in a pan pelletizer, in the granulation step, while cracking the coarse pseudo-particle in a blended raw material rolling layer piling up in the pan pelletizer concurrently with scraping of deposits by a scraper with a cracking function, the coarse pseudo particle is re-granulated to a particle of appropriate size.

Description

  The present invention relates to a method for producing a granulating raw material for sintering to be supplied to a DL type sintering machine.

Sintered ore consists of multiple brands of powdered iron ore (hereinafter also referred to simply as “ores”), auxiliary raw material powders such as limestone, quartzite, and serpentine, and miscellaneous raw materials such as dust, scale, and return minerals, It is obtained by adding moisture to a blended raw material for sintering in which an appropriate amount of solid fuel such as powder coke is blended, mixing and granulating, and charging the granulated raw material into a sintering machine and firing. At the time of granulation, the blended raw materials aggregate with each other and become pseudo particles by containing moisture. It is known that by introducing the pseudo granulated raw material for sintering into a sintering machine, it is possible to ensure good ventilation on the sintering machine and the sintering proceeds smoothly. .
In recent years, iron ore for sintering has been prone to lower grades due to depletion of high-quality iron ore, for example, an increase in slag components and pulverization, and granulation due to an increase in alumina content and an increase in the fine powder ratio. There are a lot of bad things. On the other hand, sintered ore used in the blast furnace is required to have a low slag ratio, high reducibility, and high strength from the viewpoint of reducing hot metal production cost in the blast furnace and reducing CO ₂ generation amount. .

  In such an environment surrounding the recent iron ore for sintering, high-quality sintered ore is produced by using highly granulated iron ore, which is a high-grade iron ore for pellets called pellet feed. Techniques for this have been proposed. For example, one such conventional technique is the Hybrid Pelletized Sinter method (hereinafter referred to as “HPS method”). This technology is intended to produce sintered ore with low slag ratio and high reducibility by granulating a raw material containing a large amount of fine iron ore such as pellet feed using a drum mixer and pelletizer. (Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5).

Patent Literature 1: Japanese Patent Publication No. 2-4658 Patent Literature 2: Japanese Patent Publication No. 6-21297 Patent Literature 3: Japanese Patent Publication No. 6-21298 Patent Literature 4: Japanese Patent Publication No. 6-21299 Patent Literature 5: Japan Patent Publication No. 6-60358

  However, when granulating raw materials containing a large amount of fine iron ore that is pellet feed, each fine iron ore absorbs moisture preferentially, so in the mixing process and granulation process, the fine powder simply aggregated. However, there is a problem that coarse pseudo-particles having irregular particle sizes in a form in which fine particles are attached around the core particles are generated. The reason for this is that fine iron ore such as pellet feed is more likely to absorb moisture and retain more moisture between powders as long as it has the same wettability, as long as the wettability is the same. It has been.

In this way, when coarse pseudo-particles having irregular particle sizes and weak bond strength are generated, the particle size distribution becomes wide. When this is filled on the pallet of the sintering machine, the results shown in FIGS. 1 (a) and 1 (b) are obtained. As shown, a dense packing structure is obtained, and the bulk density is increased. Moreover, if such coarse pseudo-particles are deposited on the pallet of the sintering machine with a certain layer thickness, a load (compressive force) is applied to the pseudo-particles and is easily crushed. As a result, the sintering process becomes a hindrance to the operation of the sintering machine, and there is a possibility that the sintering time becomes longer or the production yield of the sintered ore is lowered and the productivity is lowered.
Furthermore, it is unavoidable to increase the amount of quicklime used as a binder used for granulation, leading to an increase in the production cost of sintered ore, and when coating solid fuel such as powdered coke in the subsequent process, There was a problem in that the existing state of the powdered coke as a whole of the sintered raw material became non-uniform, combustion and heat receiving became non-uniform, and the firing rate was reduced.

  It is known that a pre-granulation technique should be adopted for such a problem. For example, in Patent No. 2790008, when a sintered raw material having a particle size of 0.5 mm or less is 30 wt% or more is granulated, the raw material is substantially crushed using a mixer that has a high-speed stirring blade previously incorporated. There is disclosed a pretreatment method for a sintering raw material in which mixing is performed while applying a shearing force, and the water content of the sintering raw material is 6.5 to 10.0% during this mixing.

  This treatment method is a technique for homogenizing the particle size distribution by applying shearing force instead of crushing the iron ore powder, and promoting the homogenization of moisture and the exudation of absorbed moisture to the particle surface. . However, in the method using a mixer with a built-in high-speed stirring blade, there is a problem that it is necessary to perform this treatment on all the blended raw materials charged in the mixer, resulting in a problem that the equipment scale becomes large. If the residence time is shortened so as to increase the time, there is a problem that it is impossible to secure a sufficient time required for water homogenization. Furthermore, when granulating after mixing while giving shearing force without crushing, fine particles or fine powders may reagglomerate to become coarse pseudo particles with low bonding strength, which is the problem described above. The solution was inadequate.

  Therefore, in order to solve the above-mentioned problems of the prior art, the present invention produces fine granule and fine powder in the production of a granulation raw material for sintering using a raw material for sintering containing hardly granulated fine iron ore. Proposes technology to granulate pseudo-particles that are relatively uniform in size (uniform size) by preventing aggregation and coarse pseudo-particles with a weak bond strength that contain a large amount of fine iron ore. .

  That is, as shown in FIG. 1 (c), the present invention has a structure in which fine particles and fine particles are aggregated or fine particles are adhered around the core particles, and the pseudo particles have a relatively uniform particle size and a narrow particle size distribution. A method for advantageously producing a granulated raw material for sintering comprising a raw material packed layer formed when the granulated raw material for sintering is loaded on a pallet of a sintering machine is proposed. The object is to reduce the density and shorten the firing time associated with the improvement of the air permeability and improve the sintering productivity.

  In order to achieve the above object, in the present invention, in the step of producing a granulated raw material for sintering using a blended raw material containing a difficult-to-granulate fine iron ore powder, fine particles and fine powder aggregate to weaken the bond strength. The aim was to propose a method that can overcome the problem of aggravating the air permeability of the raw material packed bed on the pallet when the sintering machine is operated by generating coarse pseudo-particles and having a large particle size distribution. As a method for this, in the present invention, by continuing the granulation while selectively pulverizing the pseudo particles having a large particle size, the generation of coarse pseudo particles having a weak bond strength is prevented, and the particle size is compared. We have succeeded in developing a method for producing pseudo-particles with a uniform particle size distribution.

  That is, the present invention includes a mixing step of adding moisture to a blended raw material containing hardly granulated iron ore and mixing with a drum mixer, and a granulating step of granulating the blended raw material with a pan pelletizer In the method for producing a granulated raw material for sintering, coarse spurious particles in the blended raw material rolling layer staying in the pan pelletizer in the granulating step are converted into a wall scraper and / or a bottom surface in the pan pelletizer. A method for producing a granulating raw material for sintering is proposed, which comprises re-granulating to the appropriate particle size while scraping off the deposits simultaneously with scraping with a crushing function comprising a scraper.

A more preferable solution of the present invention is as follows:
(1) The scraper with a crushing function can be moved and adjusted toward the residence position of the blended raw material rolling layer,
(2) The scraper with the crushing function is adjusted to move toward the residence position of the blended raw material rolling layer and the position directly below the discharge end of the transfer belt conveyor for supplying the blended raw material from the drum mixer to the pan pelletizer. Being possible,
(3) The rotation speed of the scraper with a crushing function is 8 to 300 rpm,
(4) The coarse pseudo-particles are particles in which fine particles and / or fine particles are attached to core particles, or particles in which fine particles and / or fine particles are aggregated,
(5) The size of the appropriate particles is from 16 mesh sieve to 4 mesh sieve as defined in JIS Z8801.
(6) The coarse pseudo particles are particles having a particle size of 10 mm or more.
(7) The crushing is performed by crushing coarse pseudo particles by rotation of the scraper with a crushing function,
(8) having a step of attaching coke powder to the pseudo particles produced through this step after the granulation step;
It is.

According to the method for producing a granulated raw material for sintering according to the present invention, it is possible to use high-grade but hardly granulated fine iron ore such as pellet feed as a raw material for producing sintered ore. Therefore, it is possible to advantageously produce iron ore with a low slag ratio and high reducibility and high strength. And by using such a granulation raw material for sintering as a raw material for a blast furnace, it becomes possible to reduce the amount of lump coke charged into the blast furnace, and to reduce the amount of CO ₂ generated from the blast furnace. Significant reductions and productivity improvements can be expected. Moreover, since the amount of slag generated in the blast furnace is reduced, the load on the environment can be reduced.

  Further, according to the manufacturing method of the present invention, the particle diameter of the granulation raw material for sintering becomes substantially uniform, the charging density on the pallet of the sintering machine becomes small, and the raw material packed bed (sintered bed) ), And the existence of solid fuel such as coke breeze as a whole of the sintering raw material becomes uniform, and the burning rate is shortened by improving the burning rate, thereby improving the yield and sintering productivity. be able to.

Furthermore, according to the production method of the present invention, the amount of powder coke used can be reduced, the amount of CO ₂ generated during the production of sintered ore can be reduced, and quick lime (binder) used during granulation. Therefore, the production cost of the sintered ore can be reduced.

It is a schematic diagram of the conventional raw material filling layer (a), (b) and the raw material filling layer (c) of this invention. It is a schematic diagram of the manufacturing process (c) of the structure (a) and (b) of a pseudo particle, and the conventional granulation raw material for sintering. It is an approximate line figure showing one embodiment (b) and (c) of the conventional granulation process (a) and the granulation process of the present invention. It is a basic diagram which shows other embodiment of the granulation process of this invention. It is a measurement result of the particle size distribution and granulation moisture content of the particles granulated by the conventional method and the present invention method.

  FIG. 2 shows the structure of a typical pseudo particle. FIG. 2 (a) is a diagram of pseudo-particles of coarse pseudo-particles formed by using pellet feed, in which fine or fine particles of iron ore are agglomerated with each other through moisture, and which contain a large amount of fine iron ore and have low bonding strength. An example (aggregated particle) is shown, whereas FIG. 2 (b) is an example of a pseudo particle having a structure in which fine particles or fine particles are attached around a core particle. ) Pseudo particles are stronger and have a uniform particle size. In addition, as a fine iron ore, even if it uses a normal compounding raw material as it is, the behavior as a fine powder is the same, and it is also possible to use tailing ore which is a residue generated in the process of producing a pellet feed.

  As shown in FIG. 2 (c), a general manufacturing process flow of a granulation raw material for sintering is performed by first mixing iron ore powder and auxiliary raw material powder, which are mixed raw materials cut out from the mixing tank 1, with a drum mixer 2. After mixing (mixing process), it is fed to the pan pelletizer 3 and granulated (granulation process), and further coated with a solid fuel such as coke breeze and other auxiliary materials as needed. Thus, a granulating raw material for sintering, which is a raw material for manufacturing sintered ore, is manufactured. In the mixing step and the granulating step, predetermined pseudo particles can be obtained by adding water and adjusting to obtain predetermined granulated moisture.

  By the way, the bread pelletizer 3 has a dish-like container (bread) in which the blended raw material is retained in the upper part, and the container is configured to rotate counterclockwise while being inclined at about 30 to 70 °. . The compounding raw material charged in the container of the pan pelletizer 3 is lifted to the upper position while adding moisture for granulation, and then repeatedly moves downward due to its own weight, thereby gradually growing into larger particles. It will be granulated. Therefore, in the pan pelletizer 3, the blended raw material rolls and stays in a vortex, and a large amount of the coarse pseudo particles are unevenly distributed near the surface layer of the vortex center. This is due to the phenomenon that fine particles segregate in the lower layer and coarse particles segregate in the upper layer due to the sieving effect (percolation) between the rolling particles.

  In the present invention, it is preferable to continue the granulation while preferably crushing only the coarse pseudo particles of the blended raw material charged in the pan pelletizer 3 to produce pseudo particles having a suitable particle size. For the purpose of the above, in the blended raw material generated in the mixing step by the drum mixer 4 and the granulating step by the pan pelletizer 3, coarse-grained pseudo particles in the blended raw material rolling layer staying in the pan pelletizer, That is, the particles having fine particles and / or fine particles attached to the core particles shown in FIG. 2B or the particles having fine particles and / or fine particles aggregated as shown in FIG. The material is characterized by being re-granulated to an appropriate particle size (hereinafter also referred to as “crush granulation”) while being crushed using a scraper with a crushing function.

  The coarse pseudo particles are, for example, pseudo particles in which fine particles or fine powder adhere to core particles having a particle size of 10 mm or more, preferably 8 mm or more, or fine particles or fine particles agglomerated through moisture and coarse particles. Such pseudo particles have a high moisture content and are low-strength particles that are easily deformed. Therefore, they can be crushed (collapsed) relatively easily.

According to the present invention, coarse pseudo particles contained in the raw material are crushed by a scraper with a crushing function in a pan pelletizer, and fine particles and fine powder generated thereby eventually adhere to the core particles, By agglomerating each other, pseudo particles having an appropriate size, for example, having a particle size of 16 mesh sieve to 4 mesh sieve as defined in JIS Z8801, can be re-granulated. Further, the pseudo particles under 16 mesh sieve to 4 mesh sieve specified in JIS Z8801 correspond to particles having a particle size of 1.0 mm or more and less than 4.75 mm (hereinafter simply referred to as 1.0 to 4. 75mm intermediate particles.)
In addition, as a raw material for sintered ore production, it is preferable to use pseudo particles having a uniform particle size composed of intermediate particles having a particle size of 1.0 mm to 4.75 mm. The bulk density of the packed bed (sintered bed) when deposited on the pallet of the machine is reduced, and the productivity can be improved.

By the way, as shown in FIG. 3A, the scraper S with a crushing function has conventionally been provided with a wall surface scraper 5 and a bottom surface scraper that are provided to remove the blended raw material adhering to the bottom surface and the wall surface of the pan pelletizer 3. 6 and the scrapers 5 and 6 are preferably provided so that the movement of the scrapers 5 and 6 toward the staying position of the mixed raw material rolling layer in the pan pelletizer 3 can be adjusted.
In addition, the wall surface scraper 5 and the bottom surface scraper 6 are usually configured to rotate at a rotation speed of about 10 to 40 rpm, and to scrape off the mixed raw material adhering to the bottom surface and the wall surface of the pan pelletizer 3 by the rotation. If the blended raw material adheres to the bottom surface or wall surface of the bread pelletizer 3, the internal volume of the bread, that is, the amount of the raw material is reduced, and the retention time of the raw material in the bread is shortened, so that the granulation ability is reduced, so that removal is required. Yes.

  In the present invention, the scraper S with a crushing function composed of at least one of the wall surface scraper 5 and the bottom surface scraper 6 is mixed with the blended raw material in the pan pelletizer 3 as illustrated in FIGS. 3 (b) and 3 (c). The scraper S with a crushing function is preferably rotated at a speed of 8 to 300 rpm. The scraper S with a crushing function is disposed so as to overlap with the surface layer portion, which is a dense region of coarse pseudo-particles. Rotate at high speed with numbers. In addition, when the rotation speed of the scraper S with a crushing function is less than 8 rpm, there is a concern that the raw material adheres to the blades (crushing function part) of the scraper S and causes a reduction in the crushing ability. Further, if it exceeds 300 rpm, the pseudo particles may be excessively crushed and pulverized, or the flow of the blended raw material may be inhibited by the rotation of the scraper S with a crushing function, and the number of contacts between the scraper S and the pseudo particles (contact (Probability) may be reduced, and coarse pseudo particles may not be effectively crushed.

  According to the present invention, the coarse pseudo particles enlarged in the compounding raw material rolling layer in the pan pelletizer 3 and having a particle size exceeding 10 mm are crushed by the scraper S with a crushing function. Then, the water localized in the coarse pseudo-particles is released and efficiently redistributed to the blended raw material to make the water uniform, and the particle size distribution is reduced by granulation in the pan pelletizer 3. It is possible to produce a granulation raw material for a sintering machine having a relatively uniform particle size.

  In addition, according to the research by the inventors, in the conventional HPS method, when a blended raw material containing a large amount of hardly granulated fine iron ore such as pellet feed is used, it has already been mixed with a drum mixer. In addition, fine particles or fine particles adhere to large particles that become core particles, or fine particles or fine particles aggregate together to form coarse pseudo particles with irregular particle sizes, and such coarse particles Although some of the pseudo particles are destroyed by the impact of the rolling motion inside the pan pelletizer, most of the pseudo particles are found to further increase in size (enlarge) as the granulation progresses.

Therefore, as another embodiment of the present invention, as shown in FIG. 4, a scraper S with a crushing function, together with the staying position of the mixed raw material rolling layer in the pan pelletizer 3, the belt conveyor 10 in the pan pelletizer 3. It is preferable that it is provided at a position directly below the discharge end so that the movement can be adjusted.
According to this, coarse pseudo particles (coarse pseudo particles generated in the mixing process in the drum mixer 2) already contained in the blended raw material at the time of charging into the pan pelletizer 3 are Prior to granulation, the particles are crushed to a certain particle size or less, so that the pseudo particles do not increase (enlarge) due to the progress of granulation, even if coarse particles are generated in the subsequent granulation process. Even so, it can be crushed by the scraper S with a crushing function provided at the staying position of the blended raw material rolling layer, so that the coarse pseudo-particles can be crushed reliably, the particle strength is large, and the particle size distribution Can be granulated.

  The pseudo particles pulverized and granulated as described above overflow from the pan pelletizer and are discharged onto the belt conveyor, and then, on the surface thereof, a solid fuel such as coke powder using another drum mixer. Further, by coating the auxiliary material used as necessary, it becomes a granulated raw material for sintering which is a raw material for producing sintered ore.

  Therefore, when a sintered ore is manufactured using the granulation raw material for sintering manufactured based on the method of the present invention, an improvement in the yield of sintered ore and the strength of the sintered ore can be expected. Moreover, since the granulation raw material for sintering manufactured by application of this invention becomes a comparatively uniform particle size, the existence state of the powder coke coated as a solid fuel will also be optimized. In addition, when not implementing external granulation of powder coke, uniform mixing before granulation is required to achieve uniform mixing of powder coke and limestone. Is done.

  Further, the method according to the present invention does not require an additional line for crushing, and has a simple equipment configuration in which an existing wall scraper and / or bottom scraper is used in the pan pelletizer.

In this example, 40 mass% in the iron ore is based on the conventional HPS method on the condition that the pellet feed is blended, and the wall surface scraper (FIG. 3B: Invention 1) or the bottom scraper (FIG. 3 ( c): The present invention 2) was disposed so as to be movable to the residence position of the blended raw material rolling layer, and continuous granulation was performed while crushing with the scraper.
In the conventional HPS method, the wall scraper is rotated at 40 rpm and the bottom scraper is rotated at 10 rpm. On the other hand, in the present inventions 1 and 2, each scraper is moved to the rolling region of the staying blended raw material. And rotated at a high speed of 200 rpm.
Table 1 shows the results of measuring the ratio of coarse pseudo-particles (particle size of 10 mm or more) and the sintering productivity when a sintered ore was produced using each of the granulated raw materials manufactured as described above. Show. From this result, it was confirmed that by applying the present invention (present invention 1 and present invention 2), the generation ratio of coarse pseudo-particles can be reduced and the sintering productivity can be improved.

In addition, in this example, when the state of the inside of the pan pelletizer when it was granulated by the conventional method was observed, it seems that the blended raw material attached to the wall surface / bottom surface of the pan pelletizer gradually grows as the operation time elapses. confirmed. Therefore, when the moisture content of this deposit was measured using an absolutely dry moisture meter, it was higher than the average moisture content of the charged raw material, and fine powder and fine particles aggregated on the wall and bottom of the pan pelletizer via moisture. It was found that coarse pseudo particles with low strength were formed.
In this regard, in the present inventions 1 and 2, when the state of the inside of the pan pelletizer was observed, the growth of the blended raw material adhering to the wall surface / bottom surface of the pan pelletizer was lower than that of the conventional method, and the coarseness was increased. It was confirmed that the formation of simple pseudo particles can be suppressed.

  Furthermore, in order to verify the effect of the present invention, granulated particles were collected at the same granulation time with a granulated water content of 7.2%, and the water content for each particle size distribution was measured. The result is shown in FIG. According to this result, the granulated particles using the conventional method have a high generation ratio of coarse particles having a large particle size of 8 mm or more, including many coarse particles having a particle size of 10 mm or more, and are easily deformed and have low strength. It can be seen that a lot of granulated particles are contained. On the other hand, in the granulated particles according to the method of the present invention, while the ratio of coarse particles is decreased, the ratio of intermediate particles (1.0 mm to 4.75 mm) close to the average moisture content is increased, and the particle size is uniform. Granulated particles could be produced.

  The method according to the present invention can be applied not only to the production of a granulated raw material for sintering, but also to the production technique of sintered ore for blast furnace.

DESCRIPTION OF SYMBOLS 1 Mixing tank 2 Drum mixer 3 Pamp pelletizer 4 Drum mixer 5 Wall surface scraper 6 Bottom surface scraper 10 Belt conveyor S Scraper with a crushing function

Claims (9)

Sintering through a mixing process in which water is added to a blended raw material containing difficult-to-granulate iron ore and mixed with a drum mixer, and a granulated process in which the blended raw material is granulated with a pan pelletizer In the method of manufacturing the grain raw material,
In the granulation step, coarse pseudo particles in the mixed raw material rolling layer staying in the pan pelletizer are scraped off by a scraper having a crushing function including a wall surface scraper and / or a bottom surface scraper in the pan pelletizer. A method for producing a granulating raw material for sintering, characterized by re-granulating to the appropriate particle size while simultaneously crushing. The method for producing a granulated raw material for sintering according to claim 1, wherein the scraper with a crushing function can be moved and adjusted toward a residence position of the blended raw material rolling layer. The scraper with a crushing function can be adjusted to move toward the residence position of the blended material rolling layer and the position directly below the discharge end of the transfer belt conveyor for supplying the blended material from the drum mixer to the pan pelletizer. The manufacturing method of the granulation raw material for sintering of Claim 1 characterized by the above-mentioned. The method for producing a granulated raw material for sintering according to any one of claims 1 to 3, wherein the number of revolutions of the scraper with a crushing function is 8 to 300 rpm. The coarse pseudo-particle is a particle in which fine powder and / or fine particles are attached to a core particle, or a particle in which fine powder and / or fine particles are aggregated, according to any one of claims 1 to 4. The manufacturing method of the granulation raw material for a description of description. The production of the granulated raw material for sintering according to any one of claims 1 to 5, wherein the size of the appropriate particles is from above 16 mesh sieve to below 4 mesh sieve as defined in JIS Z8801. Method. The method for producing a granulated raw material for sintering according to any one of claims 1 to 5, wherein the coarse pseudo particles are particles having a particle diameter of 10 mm or more. The granulation raw material for sintering according to any one of claims 1 to 7, wherein the crushing is performed by crushing coarse pseudo particles by rotation of the scraper with a crushing function. Method. The granulation raw material for sintering according to any one of claims 1 to 8, further comprising a step of adhering coke powder to pseudo particles produced through this step after the granulation step. Production method.

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