JP5983949B2 - Method for producing granulated raw material for sintering - Google Patents

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 iron ore for sintering, a high-quality iron ore for pellets called the pellet feed is used to produce high-quality sintered ore using the hardly granulated fine iron ore. Technology has 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 a blended raw material containing a large amount of fine iron ore that is pellet feed using the conventional HPS method, as shown in FIG. 1, not only fine particles of fine particles (less than 0.5 mm), Coarse grains (> 10 mm) were found to increase. This is because fine iron ore such as pellet feed is more likely to absorb moisture and retain more moisture between powders if the wettability is the same. Many fine iron ores absorb moisture preferentially, and the fine powders are simply agglomerated with each other, and there are many coarse pseudo particles with irregular particle sizes in the form of fine particles adhering around the core particles. It is thought that it was generated.

This point is also apparent from the following experiments conducted by the inventors.
First, granulation is performed using a raw material containing a large amount of vanadium (40 mass%) as a difficult-to-granulate fine iron ore such as pellet feed, and then the particle size distribution of the generated pseudo particles and the particle size distribution of the pellet feed Was measured. From the results, when a large amount of pellet feed is included in the blended raw material as shown in FIG. 2 (a), fine grains (less than 0.25 mm) and coarse grains (greater than 8 mm) compared to the case where the pellet feed is not included. It turned out that the weight ratio becomes high, and especially the weight ratio of the coarse particles becomes very high at about 75 wt%. Also, the particle size distribution of the pellet feed (FIG. 2 (b)) shows the same tendency as the particle size distribution of the pseudo particles, and the weight ratio of the pellet feed in the coarse particle region is as high as about 80 wt%, It was confirmed that coarse pseudo particles were formed due to the uneven distribution of the coarse particles and the aggregation of the pellet feed.
Furthermore, when the moisture content was measured for the generated pseudo particles (FIG. 2 (c)), the moisture content in the coarse grain region was high, and the pellet feed aggregated by absorbing moisture to form coarse pseudo particles. I found out.

In this way, by granulating a blended raw material containing a large amount of fine iron ore such as pellet feed, when a large number of coarse pseudo-particles with irregular particle sizes and weak bond strength are generated, the particle size distribution also increases. When the pallet of the sintering machine is filled, a dense filling structure is formed as shown in FIGS. 3A and 3B, and the bulk density is increased. Moreover, when such coarse pseudo-particles are deposited on the pallet of the sintering machine with a certain layer thickness as shown in FIG. 3B, a load (compressive force) is applied to the pseudo-particles and is easily collapsed. For this reason, the porosity is lowered, which leads to deterioration of air permeability and hinders 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 is a problem in that the existing state of the powdered coke or the like as the entire sintered raw material becomes non-uniform, combustion and heat receiving become non-uniform, and the firing rate is reduced.

  Therefore, the present invention prevents the generation of coarse pseudo-particles having a weak bond strength with irregular particle sizes in the granulation raw material for sintering when using the hardly granulated fine iron ore, A technique for granulating pseudo particles having a uniform size is proposed.

  That is, as shown in FIG. 3C, the present invention has a structure in which fine particles and fine particles are aggregated with each other or fine particles are adhered around the core particles, and the particle size is relatively uniform and the particle size distribution is narrow. A method for producing a granulated raw material for sintering consisting of particles is proposed, whereby the packing density of the raw material packed bed formed when the granulated raw material for sintering is charged on the pallet of the sintering machine. The purpose is to realize reduction and shortening of the firing time associated with improvement in air permeability, and to improve sintering productivity.

In order to achieve the above object, in the present invention, pseudo particles having a large particle size included in primary granulated particles produced by preliminary granulation processing by a primary granulator such as a pan pelletizer or a drum mixer are selected. And then re-granulating with a secondary granulator to produce a granulated raw material for sintering consisting of coarse pseudo-particles with weak bond strength in the raw material for sintering Succeeded in developing the method.
That is, the present invention includes a mixing step of mixing a blended raw material containing hardly granulated iron ore, a granulating step of granulating the mixed raw material using a primary granulator, and 1 generated in the granulating step. In a method of producing a granulated raw material for sintering through a re-granulation step of further granulating the next granulated particles with a secondary granulator,
Between the granulation step and the re-granulation step, a pulverization step using a pulverizer set to pulverize while selecting primary granulated particles having a particle size of 10 mm or more is provided, and the pulverizer is , Disposed immediately below the discharge end of the primary granulator, or on a belt conveyor connecting portion for transferring primary granulated particles from the primary granulator to the secondary granulator , A method for producing a granulated raw material for sintering, characterized by pulverizing the granulated particles , is proposed.

A more preferable solution of the present invention is as follows:
(1) Before Symbol 1 Tsugizotsubu particles, pseudo particle fines and / or fine nuclear particles adhered or fines and / or granule has a pseudo particles granulated aggregate with each other,
(2) the disintegrator, it has a mechanism in which a plurality of hammer is rotated in the reverse direction to each other roles pair projecting, it disintegrated previous SL 1 Tsugizotsubu particles,
(3) After the re-granulation step, further comprising a step of attaching coke powder to the secondary granulated particles after re-granulation,
It is.

(1) According to the method for producing a granulated raw material for sintering according to the present invention, high-grade but difficult-to-granulate fine iron ore such as pellet feed is used as a raw material for producing sintered ore. As a result, 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.
(2) Moreover, according to the manufacturing method which concerns on this invention, the particle size of the granulation raw material for sintering becomes substantially uniform, the charging density on the pallet of a sintering machine becomes small, and a raw material packed bed ( In addition to improving the air permeability of the sintering bed), the existing state of solid fuel such as powdered coke as the entire sintering raw material becomes uniform, and the firing time is shortened by improving the burning rate, thereby improving the sintering productivity. Can be made.
(3) Further, 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 used during granulation. Since the usage-amount of (binder) can be reduced, the manufacturing cost of a sintered ore can be reduced.

It is a particle size distribution figure of the granulation raw material for sintering manufactured by the conventional method. It is a measurement result of the particle size distribution (a) of the granulation raw material for sintering manufactured by the conventional method, the particle size distribution (b) of pellet feed (vanadium), and the granulated water content (c). 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 which shows the structure (a) and (b) of typical pseudoparticles. It is a schematic diagram which shows an example of the granulation raw material manufacturing process for a sintering of the conventional method and this invention method. It is a schematic diagram which shows the crushing process of this invention method. It is explanatory drawing which shows the structural example of a crusher. It is a particle size distribution figure of the pseudo particle (at the time of compounding of pellet feed 20mass%) granulated by the conventional method and this invention method. It is a comparative graph which shows the operation result (breathability index, baking time) at the time of performing a sintering test using the pseudo particle of FIG. It is a comparative graph which shows the operation result (product yield, production rate) at the time of performing a sintering test using the pseudo | simulated particle of FIG.

  FIG. 4 shows the structure of a typical pseudo particle. FIG. 4 (a) shows that among the pseudo particles formed when granulated using a difficult-to-granulate fine iron ore such as pellet feed, fine particles and fine iron ore are simply aggregated through moisture. An example of coarse quasi-particles (aggregated particles) having a low bonding strength and granulated is shown. On the other hand, FIG. 4B is an example of a pseudo particle having a structure in which fine particles or fine particles are attached around the core particle. Generally, the pseudo particle of FIG. 4B has a higher binding strength. The particle size is uniform (uniform particles). The fine iron ore includes tailing ore that is a residue generated in the process of producing the pellet feed. In the present invention, these are simply referred to as hardly granulated iron ore.

Fig.5 (a) shows the flow of the manufacturing process of the general granulation raw material for sintering. In this manufacturing process, iron ore powder, which is a blended raw material cut out from the blending tank, is mixed with mixer 1 by adding about 5 to 8 mass% of water, and added to auxiliary mixer powder as needed. In addition to mixing (mixing step), the mixture is then fed to a primary granulator 3 such as a drum mixer or a pan pelletizer, and granulated (granulated step) while adding moisture (about 3 mass%). Further, if necessary, re-granulation treatment is performed using a secondary granulator 4 while adding moisture (re-granulation step), and if necessary, solid fuel such as powdered coke and auxiliary materials are coated and baked. This is a method for producing a granulated raw material for sintering, which is a raw material for producing ore. Here, the amount of water added in the mixing step, the granulating step and the re-granulating step is adjusted so that predetermined pseudo particles are obtained, that is, predetermined granulated moisture.
In FIG. 5, one drum mixer is described as the primary granulator 3 and the secondary granulator 4, but a plurality of drum mixers, pan pelletizers, etc. may be combined. Good.

  In the present invention, in the method for producing a granulation raw material for sintering using a blended raw material containing hardly granulated iron ore, preliminary granulation by the primary granulator 3 as illustrated in FIG. Between the granulation process and the re-granulation process by the secondary granulator 4, a crushing process 5 is interposed, and the coarsely grown particles, particularly fine powder, among the primary granulated particles that have undergone the granulation process. 4 / a is characterized in that primary granulated particles having a particle size of a certain size or more are crushed among pseudo particles as shown in FIG. Yes. Accordingly, for example, coarse primary granulated particles having a particle size of 10 mm or more, preferably 8 mm or more at the outlet of the primary granulator 3 are crushed using a pulverizer described later. Then, for example, after adjusting the particle size so as to be about 1 to 8 mm, intermediate particles (particle size 1.0 to 4.75 mm are supplied to the secondary granulator 4 and re-granulated. ) Is a granulated raw material for sintering.

  In other words, difficult-to-granulate iron ore easily absorbs moisture as described above and easily retains a large amount of moisture between the powders. In addition, coarse pseudo particles having irregular particle sizes in a form in which fine powder is attached around the core particles are easily formed. Therefore, in the present invention, after preliminary granulation is performed by the primary granulator 3, coarse particles contained in the primary granulation particles are regenerated by the secondary granulator 4. Prior to the granulation process, in the pulverization process 5, the powder is pulverized to a certain particle size or less, and the fine powder and moisture localized in the coarse primary granulated particles are released to be uniform throughout the granulated raw material. By dispersing, in the re-granulation process in the secondary granulator 4, there is no occurrence of coarse pseudo particles with a weakened bond strength with an enlarged particle size exceeding 10 mm, and the particle size distribution Therefore, it is possible to produce a granulation raw material for a sintering machine composed of equalized pseudo particles having a small particle size and a relatively uniform particle size.

In the present invention, the crushing step 5 is performed at a position immediately below the discharge end of the primary granulated particles from the primary granulator 3 comprising the pan pelletizer 3a or the drum mixer 3b, as shown in FIG. A disintegrator 7 provided with a disintegration mechanism to be described later is disposed on a connecting portion (not shown) of the belt conveyor 6 for conveying the granulated particles from the first granulator 3 to the second granulator 4, by該解crusher 7, intends row by crushing (pulverizing) while selecting coarse 1 Tsugizotsubu particles on certain particle size or less.
The fine particles and fine powder generated by crushing by the crusher 7 are transported by the belt conveyor 6 together with the granulated particles after crushing, and charged into the secondary granulator 4, where the secondary granulator In the inside, the particles 4 aggregate with each other or adhere to the core particles and re-granulate into pseudo particles.

By the way, coarse primary granulated particles are not only pseudo particles in which fine particles or fine particles are attached to the core particles, but also fine particles or fine particles are simply passed through moisture as described above. Pseudoparticles that are agglomerated and coarsened, especially in the case of compound raw materials that contain a large amount of pellet feed and tailing ore, which are difficult to granulate iron ores, Since it does not have particles, the strength is low, and it can be crushed (collapsed) by the crusher 7 relatively easily.
The secondary granulated particles after the re-granulation step are coated with a solid fuel such as coke powder or auxiliary materials on the surface as necessary, and the granulated raw material for sintering, which is a raw material for producing sintered ore It becomes.

As shown in the explanatory diagram of FIG. 7, the crusher 7 used in the present invention includes two crushing rolls 9a and 9b that rotate in opposite directions with a plurality of crushing teeth 8a and 8b projecting from each other. Coarse particles contained in the primary granulated particles by passing the primary granulated particles after the granulation step between the rotating pulverizing rolls 9a and 9b. While being selected by the crushing teeth 8a and 8b meshing with a certain clearance, they are gradually crushed and discharged as particles having a certain particle size or less.
In addition, since the crushing teeth 8a and 8b projecting from the crushing rolls 9a and 9b have pseudo particles having an appropriate particle size (for example, 5 mm or less), the gap A between the tooth tip and the opposing roll surface is The height B is set to 5 mm or less, and the height B of the crushing teeth 8a and 8b is set to about 5 to 10 mm so that the crushing teeth 8a and 8b mesh with each other. Moreover, it is preferable that the space | interval C between the crushing teeth 8a and 8b to mesh and the pitch D of the crushing teeth 8a and 8b shall also be 5 mm or less.

  Further, the clearance and tooth shape of the crushed teeth 8a and 8b, and the rotational speed of the rolls 9a and 9b are the particle size distribution of the blended raw material, the water content, strength, and the feed rate required for producing a certain amount of sintered ore. It is preferable to adjust appropriately according to various conditions, such as, and according to this, a coarse grain can be disintegrated more selectively, without pulverizing a compounding raw material excessively.

FIG. 8 is a diagram showing a method for producing a sintered product manufactured by the present invention method and the conventional HPS method using a blended raw material containing 20 mass% of a hard-to-granulate pellet feed in iron ore (16 mass% for Wasco pellet feed, 4 mass% for choggle tailing). The average particle diameter and particle size distribution of the granulation raw material (pseudo particle) are compared and shown.
According to this, in the method of the present invention, the generation ratio of coarse particles (10 mm or more) often found in the conventional method is decreased, the ratio of intermediate particles of 1.0 to 4.75 mm is increased, and the particle size is increased. It can be seen that a uniform granulated raw material for sintering could be produced. Further, in the method of the present invention, the average particle size of the granulated raw material for sintering is increased by 0.08 mm (1.62 → 1.70 mm) despite being subjected to the crushing step. This is because fine powder and moisture inherent in coarse primary granulated particles (pseudo particles) are uniformly dispersed by passing through a crushing step after granulation by the first granulator. It is considered that the re-granulation of fine powder and fine particles was promoted by being put into the second granulator in a state, and a granulation raw material for sintering having a larger average particle diameter than that of the conventional method was produced. .

  9 and 10 show the results of a sintering test when a sintered ore was produced using the granulating raw material for sintering (pseudoparticles) shown in FIG. In the method of the present invention, by providing a crushing step, the yield of sintered ore production is slightly reduced compared to the conventional HPS method, but the granulation raw material for sintering is sized to narrow the particle size distribution. It has been found that the air permeability of the granulated raw material packed layer (sintered bed) for sintering is improved and the firing time is greatly shortened, thereby obtaining the effect of improving the sintering production rate.

  Therefore, when a sintered ore is manufactured using the granulation raw material for sintering manufactured based on the method of this invention, the improvement of sintering productivity and the intensity | strength of a sintered ore can be anticipated. 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.

  In addition, the method according to the present invention does not require an additional line for crushing, and can be applied directly below the discharge end of the first granulator such as a drum mixer or a pan pelletizer, or at a connecting portion of an existing belt conveyor. A simple equipment configuration with only a crusher.

  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, 2 Mixer 3 Primary granulator 3a Pam pelletizer 3b Drum mixer 4 Secondary granulator 5 Crushing process 6 Belt conveyor 7 Crusher 8a, 8b Crushing teeth 9a, 9b Roll

Claims (4)

A mixing step of mixing a blended raw material containing hardly granulated iron ore, a granulating step of granulating the mixed raw material using a primary granulator, and primary granulated particles generated in the granulating step In a method of producing a granulation raw material for sintering via a re-granulation step of granulating with a secondary granulator,
Between the granulation step and the re-granulation step, a pulverization step using a pulverizer set to pulverize while selecting primary granulated particles having a particle size of 10 mm or more is provided, and the pulverizer is , Disposed immediately below the discharge end of the primary granulator, or on a belt conveyor connecting portion for transferring primary granulated particles from the primary granulator to the secondary granulator , A method for producing a granulating raw material for sintering , comprising pulverizing granulated particles. Before Symbol 1 Tsugizotsubu particles claims, characterized in that the pseudo particles fines and / or fine nuclear particles adhered or fines and / or granules, a pseudo particles granulated aggregate each other 2. A method for producing a granulating raw material for sintering according to 1. The disintegrator may be rotated in the opposite direction a plurality of hammer roll pair projecting from the mutually claim 1 or pre Symbol 1 Tsugizotsubu particles and having a mechanism for crushing 2. A method for producing a granulating raw material for sintering according to 2.   The sintering according to any one of claims 1 to 3, further comprising a step of attaching coke powder to the secondary granulated particles after re-granulation after the re-granulation step. A method for producing a granulated raw material.

Images