JPH11236628A - Pre-treatment of sintering raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for pre-treating a sintering raw material, with which fine grain contained in the sintering raw material is made pseudo-grain having suitable size and the permeability of a sintering raw material layer is better than that of the conventional method. SOLUTION: In mixing the raw material for producing the sintered ore for blast furnace with a Dweight Lloyd type sintering machine by using a drum type mixer 5, the raw material 1 is charged into a truncated cone shaped rotary cylindrical body and screened, and the grain in the finest side in the screened grains is palletized by adding the moisture in a pelletizer 3 and the pellet having large diameter is mixed with the grain in the coarse side with the drum type mixer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment method for a sintering raw material, and more particularly to a method for producing a sintered ore to be charged into a blast furnace using a Dwight Lloyd (hereinafter referred to as DL) type sintering machine. This is a technique for optimizing the raw materials used.

[0002]

2. Description of the Related Art In order to produce a sintered ore as a raw material for a blast furnace using a DL type sintering machine, first, limestone and coke fine are added to and mixed with fine iron ore, and water is added thereto to form a drum. Mix and granulate with a mold mixer to prepare a raw material for sintering. And
The sintering raw material is supplied to an endless pallet that is rotationally driven on a DL sintering machine via a hopper, and forms a sintering raw material layer (hereinafter referred to as a sintering raw material layer). The DL sintering machine is provided with an ignition furnace in which a plurality of combustion burners are arranged in the width direction, and the pallet is moving. When passing through, the coke breeze in the upper layer is ignited. In addition, a wind box (also referred to as a wind box) is closely arranged below the pallet, and the inside of the pallet is under a negative pressure by an intake blower.・ It is called front)
Progresses from the upper part to the lower part while the pallet moves to the terminal side of the sintering machine. In the combustion zone, a reaction occurs in which limestone is thermally decomposed into quicklime, a reaction in which iron ore particles and quicklime react to form a melt, and a phenomenon in which particles fuse together through the melt occurs. Eventually, the entire sintering raw material layer becomes massive. This lump is crushed and classified after being discharged from the rear end of the sintering machine, to be a sintered ore having a predetermined particle size distribution. Therefore, in order to efficiently produce high-quality sintered ore, the air permeability in the sintering material layer, that is, the ease with which air can escape from the upper surface to the lower surface of the sintering material layer is an important factor. Various pre-processing is performed.

[0003] By the way, when the fine powder increases in the sintering raw material,
As a matter of course, the permeability of the sintering raw material layer is reduced. For this reason, conventionally, water has been added to the sintering raw material in a drum type mixer to granulate the fine powder to adhere to particles having a relatively large particle size, thereby apparently increasing the size of the particles ( This is called pseudo-particle formation). However, granulation in such a drum mixer is not always in a satisfactory state.

Therefore, Japanese Patent Publication No. Sho 62-47928 and Japanese Patent Publication No. Hei 1-53335 have proposed a technique in which fine powder is previously enlarged by compression molding or extrusion molding, and then granulated in addition to a sintering raw material. However, this Tokujin Sho 62
The techniques described in JP-A-47928 and JP-B-1-53335 are intended only for fine powders containing no coarse particles, and the amount of the enlarged fine particles used in the entire sintering raw material is small, so that the air permeability is low. Was not as effective as expected. Furthermore, iron ore powder, which accounts for the majority of sintering raw materials, has a wide particle size distribution from fine powder to coarse particles,
In order to granulate only the fine powder portion, a separate classification operation is required.

Japanese Patent Application Laid-Open No. 9-194856 discloses a technique for forming fine particles into pseudo-particles through the classification operation.
"Pre-processing method of sintering raw material as sintering raw material by sieving fine ore with a sieving machine, kneading the ore under the sieve with a kneading machine, granulating with a granulator (usually using a pan pelletizer) Discloses a technique of adding water to the ore under the ore during the sieving. As a result, only the fine powder in the sintering raw material was enlarged, and thereafter, the particles were combined with particles of a normal size and mixed by a mixer to obtain a sintering raw material.

However, since this technique uses a general sieve for the classification operation, there is a restriction in the clogging of the sieve and the processing amount, and it has not been realized yet.

[0007]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a sintering method in which fine particles contained in a sintering raw material are converted into pseudo-particles of an appropriate size, and the permeability of the sintering raw material layer is improved as compared with the prior art. It is intended to provide a pretreatment method for raw materials.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, the inventor has worked diligently to smooth the preliminary classification of the sintering raw materials used in the DL type sintering machine, and has completed the results as the present invention. Was. That is, according to the present invention, when a raw material for producing a blast furnace sintered ore with a Dwight Lloyd type sintering machine is mixed by a drum type mixer, the raw material is mounted on a horizontally-turned truncated conical rotary cylinder. And then classified, and the classified finest particles are granulated by adding moisture in a granulator, and the large-diameter particles are mixed with the coarse particles by the drum type mixer. This is a method for pre-processing sintering raw materials, which is a feature.

The present invention is also a method for pre-treating a sintering raw material, wherein the raw material is a powder of iron ore, limestone, dolomite, and serpentine. Further, the present invention is a method for pre-treating a sintering raw material, which further comprises mixing the coke powder with the drum type mixer. In addition, the present invention is a method for pre-processing a sintering raw material, wherein the classification is performed at a particle diameter of 2 mm of the raw material.

[0010] In addition, the present invention provides the above granulator,
It is also a pretreatment method for a sintering raw material, characterized in that it is a roll compression molding machine, or that granulation in the granulator is performed to a particle diameter of 3 to 10 mm. ADVANTAGE OF THE INVENTION According to this invention, the continuous classification of the raw material which was difficult conventionally can be performed smoothly, and coarsening of fine particles can be easily achieved. As a result, the permeability of the sintering raw material layer is improved as compared with the conventional method, and high quality sintered ore for blast furnaces can be efficiently mass-produced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows the steps until the raw materials are charged into a DL-type sintering machine according to the pretreatment method according to the present invention. According to FIG. 1, the raw material 1 is supplied to a classifier 11, where it is classified into a fine grain side and a coarse grain side. Then, only the fine granule side is supplied to the granulator 3, and after being increased in diameter by adding moisture, is sent to the drum mixer 5. On the other hand, the coarse-grain side is directly supplied to the drum-type mixer 5 and mixed together with the fine-grain side and the coke powder 4 supplied by another route. 6. The raw material 1 is iron ore, limestone, serpentine, quartzite, slag generated in a blast furnace or a converter, so-called remineralization generated in the sintering machine 6, and the like. Table 1 shows the compounding ratios of these compounds in Table 2 after compounding (hereinafter referred to as “raw material 1 before classification”).
An example of the particle size distribution is shown below.

[0012]

[Table 1]

[0013]

[Table 2]

An important point of the present invention is that the classifier 11 is changed from a sieve type to a rolling separation type of particles in the above process. As shown in FIG. 2, it is formed by a truncated frustoconical cylinder 2. The cylinder 2 is rotating at a predetermined speed. In this case, the raw material 1 before classification supplied near the center of the cylindrical body 2 is repeatedly rolled up and down along the wall of the cylindrical body 2. By this movement, the fine-grain side 7 of the supplied raw material 1 before classification gathers downward as shown by the arrow A in FIG. 2 and flows to the large-diameter side of the cylindrical body 2 by utilizing the inclination of the wall. On the other hand, the coarse grain side 8 gathers on the surface as shown by the arrow B,
In addition, it flows to the small diameter side of the cylindrical body 2. Therefore, outlets 12 are opened at both ends of the cylindrical body 2 and appropriate partition plates 9, 10
Is provided, the supplied raw material 1 before classification is continuously separated into one having many fine particles and one having many coarse particles, and is discharged from the cylindrical body 2. The boundary grain size between the fine grain side and the coarse grain side by this classification can be adjusted by the height of the partition plates 9 and 10 provided at the outlet 12, but in the present invention, the load of the granulator 3 arranged in the subsequent process is adjusted. Is preferably selected from the range of 0.5 to 2 mm in order to suppress the above. The particle size is 0.5 to 1.0 m.
It is more preferable that the weight is selected from the range of m because the load on the granulator can be further suppressed. Here, the lower limit of the boundary particle diameter is set to 0.5 mm. When there is a large amount of 0.5 mm or less on the coarse particle side, when the raw material becomes a sintering raw material as it is, the ventilation of the raw material layer rapidly deteriorates. Therefore, at least 0.5m
This is because it is necessary to separate and granulate in order to improve the ventilation. Further, the separation granulation exceeding the particle diameter of 2 mm excessively increases the load on the granulator. In order to suppress this load, the upper limit of the boundary particle diameter is set to 2 mm in the present invention. If the particle diameter exceeds 2 mm, the adverse effect on the ventilation of the raw material layer is reduced as it is.

In addition, in the present invention, the upper limit of the boundary particle diameter is desirably set to 1 mm or less, because only a part of the raw material before classification becomes a load of the granulator, and the load of the granulator is reduced. This is because when the portion of 1 mm or less is granulated, the effect of improving the ventilation is greatly improved, and both the reduction of the load on the granulator and the improvement of the ventilation are satisfied.

That is, as an example of the raw material 1 before classification having the particle size distribution shown in Table 2, it is assumed that the particle size is 2 m
m or less is about 60% by weight, 1mm or less is about 43% by weight,
0.5 mm or less is about 30% by weight. When the raw material 1 before classification is supplied to a classifier and classified with a boundary particle diameter of 1 mm,
As a result of rolling inside, granulation also occurs during classification. Therefore, as described above, even if about 43% by weight of a particle diameter of 1 mm or less is present, the amount actually classified at 1 mm by this classification operation is about 10% by weight. This weight percent
Then, the granulation load in the subsequent granulator is light, and it is possible to prevent a large increase in the processing cost. In addition, particle diameter 2
Even if the diameter is less than mm, the amount actually classified is reduced, but the processing cost is liable to increase as compared with the ventilation improvement effect.

It is desirable that an appropriate amount of water be added to the raw material 1 before classification supplied to the classifier 11. This is because the addition of moisture increases the size of the fine powder and improves the strength of the granulated product. At that time, a binder (a so-called binder) may be added as necessary. According to the rolling separation, the classification efficiency is lower than that of the sieve classification, but clogging and insufficient processing capacity can be eliminated.

Next, in the present invention, the type of the granulator 3 used in the step of FIG. 1 is not particularly limited. This is because it is only necessary to granulate the fine particles to a size of about 3 to 10 mm. For example, a roll compression molding machine, an extrusion molding machine, a bread pelletizer, or the like can be used. Here, the reason why the particle size of the granulated material is preferably 3 to 10 mm is 3 mm
If it is less than 10 mm, the effect of improving the air permeability of the sintering material layer by granulation is small, and if it is more than 10 mm, large particles increase too much and sintering becomes insufficient. Raw material usage-bedding ore usage) and sinter ore shutter strength (2
This is because the value of +10 mm after dropping four times from the height of m onto the iron plate is reduced.

Further, in the present invention, the coke powder 4 is added after the classification and granulation of the raw material 1 before classification. The reason is that when the coke powder 4 is contained in the granulated material, the flammability of the coke powder 4 is reduced, the temperature of the combustion zone cannot be sufficiently secured, and the sintering phenomenon becomes insufficient. In addition, the sintering time becomes longer, which is not desirable. In addition, the particle size of the coke powder 4 is desirably 1 mm or less in order to improve the adhesion to the granulated material and coarse particles during the pretreatment.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pretreatment method for a sintering raw material according to the present invention was carried out using the apparatus shown in FIGS. Manufactured. Table 1 shows the blending of raw material 1 and the particle size distribution after blending.
And 2, and the specifications of the truncated cone classifier (hereinafter, classifier 11) and the granulator 3 (roll compression molding machine) are as follows.

Maximum inner diameter of classifier cylinder: 2 m Minimum inner diameter of cylinder: 1.5 m Length of cylinder: 4 m Rotation speed of cylinder: 18 rpm Outer diameter of granulator roll: 1000 mm roll Rotation speed: 8 rpm The supply amount of the raw material 1 before classification was 5 tons / minute, and the operation was continuously performed for 8 hours. Classifier 11
Then, 7% by weight of water was added to the supplied raw material 1 before classification, and the particle size at the classification boundary was 1 at the height of the partition plates 9 and 10.
mm. Further, in the granulator 3, the particle size of the granulated product was set to about 8 mm.

By performing such an operation, in the classifier 11,% of the raw material supply amount was almost constantly discharged to the fine grain side of 1 mm or less, and the remainder flowed to the coarse grain side. Therefore, finally, the particle size distribution of the sintering raw material 13 via the drum type mixer 5 and the airflow resistance (differential pressure Δ) as the sintering raw material layer (thickness L)
P / thickness L) was as shown in Table 3. On the contrary,
The operation was also performed by the conventional raw material pretreatment method without using the classifier 11 and the granulator 3. Table 3 shows the results at the same time. From Table 3, it is clear that the ventilation resistance of the sintering raw material 13 prepared by the pretreatment method according to the present invention is significantly smaller than the value obtained by the conventional method.

[0023]

[Table 3]

Subsequently, these sintering raw materials 13
The sintering operation was performed by continuously loading the pallet of the DL type sintering machine 6. The results are shown in FIG. 3 in terms of the productivity and yield of the sinter. From FIG. 3, the yield of the sintered ore obtained through the pretreatment method according to the present invention is remarkably higher than that obtained through the conventional pretreatment method that does not perform classification and granulation of fine particles. It was confirmed that an increase in productivity was achieved. In addition, the strength of the sintered ore was improved due to the effect of densification of the fine ore by granulation.

The main sintering conditions were as follows. Thickness (L) of sintering raw material layer: 520 mm Pallet traveling speed: 2.9 m / min Negative pressure of wind box: 1500 mmH ₂ O

[0026]

As described above, according to the present invention, the permeability of the sintering raw material can be greatly improved as compared with the prior art. As a result, the productivity of the sintered ore was able to be improved more than before.

[Brief description of the drawings]

FIG. 1 is a flow chart of a process for carrying out a pretreatment method for a sintering raw material according to the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a frustum-shaped classifier used for carrying out the present invention.

FIG. 3 is a diagram comparing the results of sintering operations with sintering raw materials via the present invention and a conventional pretreatment method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material (raw material before classification) 2 Frustoconical cylindrical body 3 Granulator 4 Coke powder 5 Drum mixer 6 DL type sintering machine (sintering machine) 7 Fine-grained raw material 8 Coarse-grained raw material 9 Fine-grain side partition Plate 10 Coarse-grain side partition plate 11 Classifier 12 Outlet 13 Sintering raw material

Claims (6)

[Claims] When mixing a raw material for producing a blast furnace sintered ore with a Dwight Lloyd type sintering machine by a drum type mixer, the raw material is charged into an inverted truncated conical rotary cylinder. Then, the classified finest particles are granulated by adding moisture in a granulator, and the large-sized particles are mixed with the coarse particles by the drum mixer. Pre-treatment method for sintering raw materials. 2. The method for pre-treating a sintering raw material according to claim 1, wherein the raw material is a powder of iron ore, limestone, dolomite, and serpentine. 3. The pretreatment method for a sintering raw material according to claim 1, wherein said drum type mixer further mixes with coke powder. 4. The pretreatment method for a sintering raw material according to claim 1, wherein the classification is performed at a particle diameter of the raw material of 2 mm. 5. The pretreatment method for a sintering raw material according to claim 1, wherein the granulator is a roll compression molding machine. 6. The granulation in the granulator is carried out with a particle diameter of 3 to 1.
The method for pre-treating a sintering raw material according to any one of claims 1 to 5, wherein the method is performed up to 0 mm.