KR100711762B1 - Pelletizer for granulating fine particles - Google Patents

Abstract

Pelletizer for assembling fine powder according to the present invention is the first pelletizer pan, the connecting shaft formed in the center of the first pelletizer pan in the vertical direction of the first pelletizer pan, and the first pelletizer pan and concentric circles And a second pelletizer pan which is coupled to the first pelletizer pan by a connecting shaft.

Pelletizer, Selective Assembly, Iron Ore, Fine Powder, Dust, Mara Mamba, Limonite, High Crystalline Ore

Description

Pelletizer for Fine Powder Assembly {PELLETIZER FOR GRANULATING FINE PARTICLES}

1 is a schematic perspective view of a pelletizer for assembling fine powder according to an embodiment of the present invention.

Figure 2 is a schematic diagram showing the flow of the fine raw material by the pelletizer for fine powder raw material assembly according to an embodiment of the present invention.

3 is a graph showing the relationship between the residence time of raw materials and the granulation index.

Figure 4 is a view showing the internal structure of the pelletizer fan provided in the pelletizer according to an embodiment of the present invention.

5 is a cross-sectional view taken along the line VV of FIG. 1.

Figure 6a is a graph showing the relationship between the depth and the droplet ratio of the pelletizer pan.

6B is a graph showing the relationship between the depth of the pelletizer pan and the residence time.

Figure 7a is a graph showing the relationship between the slope and the droplet rate of the pelletizer pan.

7B is a graph showing the relationship between the slope of the pelletizer pan and the residence time.

8A to 8E are schematic diagrams showing the flow of raw materials according to the rotational speed of the pelletizer pan.

9 is a view showing a process of assembling raw materials using a pelletizer for assembling fine powder according to an embodiment of the present invention.
<Description of the symbols for the main parts of the drawings>
100: pelletizer 10: first pelletizer pan
30: connecting shaft 50: second pelletizer pan
70: support 90: drive shaft
D ₁ : Diameter of First Pelletizer Pan D ₂ : Diameter of Second Pelletizer Pan
h: Height of the connecting shaft h ₁ : Depth of the first pelletizer pan
h ₂ : depth of the second pelletizer pan
α: angle formed by the second pelletizer pan from the ground e: ground
120: differential raw material 140: granulated raw material
200: first storage bin 300: high speed stirring mixer
400: second storage bin 500: primary mixer
600: secondary mixer 700: optional assembly

The present invention relates to a pelletizer (pelletizer) for assembling fine powder, and more particularly, to a pelletizer for assembling a powdered iron ore having a small particle size and a high fine powder content.

In general, raw materials used in the production of sintered ore in the sintering process of steel mills usually include iron ore of 8 to 10 mm or less, CaO-containing raw materials such as limestone and quicklime having a smaller particle size, and SiO _2- containing raw materials such as silica and serpentine, and coke or Solid fuels, such as anthracite coal, are included.

The blending ratio of these raw materials is determined in consideration of the quality and composition of the sintered ore. After the compounding ratio is determined, each raw material is supplied in a predetermined amount in the raw material storage bin according to this compounding ratio, these are mixed in a drum mixer, and granulated by adding an appropriate amount of water.

However, when iron ore or dust containing 20% or more of particles having a particle size of 0.15 mm or less is used as a blending material, there is a problem in that a greater amount of water is added than a general raw material due to poor granulation of the raw materials. .

In order to solve this problem, a selective assembling method for separating the fine powder from other raw materials and assembling them separately is used. Such selective granulation processes generally include a step of uniformly mixing fine ore and water using a high speed stirring mixer and a step of assembling the raw materials mixed in the high speed stirring mixer with a pelletizer. The raw materials are added to the remaining raw materials and reassembled.

When the raw material of the fine powder added to a high-speed stirring mixer and added with a certain ratio of moisture is supplied to a pelletizer pan, particles are gradually grown while the raw materials flow inside the pelletizer pan, whereby granulation is performed.

As such, as the raw materials flow inside the pelletizer pan, segregation occurs depending on the particle size of the raw materials. In general, the larger the particle size, the more concentrated the upper and the wall side of the pan, the smaller the particle size is concentrated in the depth and rotation center direction of the pan. Eventually, the coarse raw material is discharged to the outside of the pan. Depending on the operating conditions, the coarse raw material may be mixed with a plurality of fine raw materials.

The process of assembling the finely divided raw material by the pelletizer is influenced by factors such as diameter, tilt, rotation speed and depth of the pelletizer pan. If the feed rate of the raw material supplied to the pelletizer under the condition of these factors is increased, the residence time of the raw material stays in the pelletizer pan is reduced, and the granulation of the fine powder is deteriorated.

Reducing the feed rate of the raw materials supplied to the pelletizer can increase the relative residence time of the fine raw materials in the pan, thereby improving the granulation of the fine raw materials. However, there is a problem that the feed cost of the raw material is reduced and ultimately the performance of the pelletizer.

It is also possible to smooth the angle of the pelletizer pan in order to increase the residence time. However, there is a problem that the appropriate number of revolutions of the pelletizer pan is small and the segregation of the raw material inside the pelletizer pan is uneven.

In addition, when increasing the depth of the pelletizer pan in order to increase the residence time, there is a problem that segregation also occurs unevenly at a certain depth or more does not improve the assembly.

If the diameter of the pelletizer pan is increased, the residence time of the raw material is increased, and thus, the assembly performance may be improved.

Accordingly, the present invention is to solve the above problems, in the assembling the fine iron ore raw material, the raw material to be assembled without changing the slope, depth, size, feed rate of the raw material of the pelletizer pan, etc. Another object of the present invention is to provide a pelletizer for assembling fine raw materials, which can be used for a long time in a pelletizer pan.

In order to achieve the above object, the pelletizer for assembling fine powder according to the present invention has a first pelletizer pan and a connection formed in the vertical direction of the first pelletizer pan at the center of the first pelletizer pan. And a second pelletizer fan which is concentric with the shaft and the first pelletizer fan and is coupled to the first pelletizer fan by a connecting shaft.

In this case, the diameter of the second pelletizer fan may be smaller than the diameter of the first pelletizer fan, and the diameter of the second pelletizer fan may be 0.67 to 0.75 times the diameter of the first pelletizer fan. Can be.

In addition, the depth of the second pelletizer pan can be smaller than the depth of the first pelletizer pan, and the depth of the second pelletizer pan can be 0.1 to 0.14 times the diameter of the second pelletizer pan. have.

In addition, the connecting shaft may have a length of at least 0.07 times the diameter of the second pelletizer pan, the connecting shaft may be formed in a cylindrical shape.

The first pelletizer and the second pelletizer pan may be at an angle of 40 ° to 60 ° with the ground. In addition, the finely divided raw material that is the object of granulation may include iron ore.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the embodiments of the present invention described below are for illustrating the present invention, and the present invention is not limited thereto.

1 schematically shows a pelletizer 100 according to an embodiment of the present invention. The shape of the pelletizer 100 shown in FIG. 1 is merely for illustrating the present invention, but the present invention is not limited thereto.

As shown in FIG. 1, the pelletizer 100 according to an exemplary embodiment of the present invention includes a first pelletizer fan 10, and has a cylindrical shape on an inner upper surface center of the first pelletizer fan 10. The connecting shaft 30 is installed. The second pelletizer fan 50 having a diameter and depth smaller than the diameter and depth of the first pelletizer fan 10 is further installed on the connecting shaft 30.

In addition, a lower support 70 having an electric motor (not shown) rotates the first pelletizer fan 10 and the second pelletizer fan 50 through the drive shaft 90. Since the structure of the support 70 provided with the electric motor can be easily understood by those skilled in the art, the description thereof will be omitted.

Referring to the operation of the pelletizer 100 as follows. The fine powder raw material in which the moisture is appropriately mixed in advance is supplied to the second pelletizer pan 50. The finely divided raw material supplied to the second pelletizer pan 50 is assembled while flowing inside the second pelletizer pan 50, and then dropped to the first pelletizer pan 10.

The granulated fine powder is flowed in the first pelletizer pan 10 for a predetermined time and discharged to the outside. As a result, the residence time of the raw material in the pelletizer pans 10 and 50 becomes long, thereby improving the assembly. This will be described with reference to FIG. 2.

As shown in FIG. 2, in the pelletizer according to the exemplary embodiment of the present invention, the first pelletizer fan 10 and the second pelletizer fan 50 rotate together in a clockwise direction, as indicated by arrows. As the raw material flows. In the first pelletizer fan 10 and the second pelletizer fan 50, the raw materials flow independently of each other. Thus, the second pelletizer pan 50 does not interfere with the flow of raw material in the first pelletizer pan 10.

In addition, since the raw material assembled in the second pelletizer fan 50 is continuously supplied to the first pelletizer fan 10 and flows again, the residence time of the raw material is extended to greatly improve granulation.

Although there are various ways of indicating the granulation characteristics of the pelletizer pan, in the present invention, a value obtained by measuring the weight ratio of particles having a particle size of 1 mm or less before and after granulation is represented by a granulation index GI 1.0 (%). The assembly index can be expressed as follows.

GI 1.0 (%) = 100 (W ₁ -W ₂ ) / W ₁ (W ₁ is a weight ratio of particles having a particle size of 1 mm or less before granulation, and W ₂ is a weight ratio of particles having a particle size of 1 mm or less after granulation.)

 Using Equation 1, the larger the value of GI1.0 (%), the better the assembly and the lower the assembly can be determined quantitatively poor.

3 shows the relationship between the residence time of raw materials and the granulation index. Experiments using different iron ores with different residence times resulted in the same results as in FIG. 3. As shown in FIG. 3, as the time for the raw material to stay inside the pelletizer pan increases, the granulation property also increases linearly in proportion to the residence time.

However, if the residence time exceeds a certain value, the granularity does not increase significantly even if the residence time greatly increases. Therefore, it is very important to increase the residence time of the raw material inside the fan within the range in which the granularity increases linearly with the change of residence time. Therefore, the specifications of the pelletizer fan must be properly limited for this purpose. Hereinafter, the specification of the pelletizer fan will be described in more detail.

FIG. 4 shows the pelletizer pans 10 and 50 provided in the pelletizer shown in FIG. 1. In the pelletizer according to an embodiment of the present invention, the raw material is supplied to the upper second pelletizer pan 50 to be assembled first. Next, the raw material is dropped into the first pelletizer fan 10 under the second pelletizer fan 50 and reassembled.

Therefore, the diameter D ₂ of the upper second pelletizer pan 50 may be equal to the diameter of the lower first pelletizer pan 10 so as to prevent the raw material from falling out of the pelletizer without being assembled. Must be less than D ₁ ). In particular, the diameter D ₂ of the second pelletizer pan 50 is preferably 0.67 times to 0.75 times the diameter D ₁ of the first pelletizer pan 10.

When the diameter (D ₂ ) of the second pelletizer fan 50 is less than 0.67 times the diameter (D ₁ ) of the first pelletizer fan 10, even if sufficient time is given, the raw material is not well assembled. 1 Fall to the pelletizer pan (10). Therefore, the installation effect of the 2nd pelletizer fan 50 is insignificant.

In addition, when the diameter D ₂ of the second pelletizer pan 50 exceeds 0.75 times the diameter D ₁ of the first pelletizer pan 10, the raw material is the second pelletizer pan 50. ), The raw material is lost to the outside of the pelletizer without falling into the first pelletizer fan 10.

5 shows a cross section of the pelletizer pans 10, 50. The depth h ₂ of the second pelletizer pan 50 varies according to the diameter D ₂ of the second pelletizer pan 50. The depth h ₂ of the second pelletizer pan 50 is suitably 0.1 to 0.14 times the diameter D ₂ of the second pelletizer pan 50.

When the depth h ₂ of the second pelletizer pan 50 is less than 0.1 times the diameter D ₂ of the second pelletizer pan 50, the finely divided raw material is transferred from the second pelletizer pan 50. Do not have sufficient residence time. Therefore, the assembling efficiency of a raw material falls. On the contrary, when the depth h ₂ of the second pelletizer pan 50 exceeds 0.14 times the diameter D ₂ of the second pelletizer pan 50, the residence time becomes longer, but the segregation of the raw material becomes uneven. do.

On the other hand, the second pelletizer fan 50 should be installed away from the first pelletizer fan 10 at a distance such that the raw material does not interfere with the flow. Therefore, the distance between the first pelletizer fan 10 and the second pelletizer fan 50, that is, the height h of the connecting shaft 30 is the diameter D ₂ of the second pelletizer fan 50. It is formed at 0.07 times or more.

As the depth of the pelletizer pan changes, the area of stock available to hold the raw material changes. In this case, it is assumed that several conditions affecting the pelletizer operation are constant. Therefore, the residence time of the raw material is changed inside the pelletizer pan, and the granulation of the raw material is greatly changed.

6A shows the relationship between the depth and the droplet ratio of the pelletizer pan. As shown in FIG. 6A, as the depth of the pelletizer pan becomes deeper, the droplet rate of the raw material increases. In addition, as shown in FIG. 6B, as the depth of the pelletizer pan becomes deeper, the residence time of the raw material increases, thereby improving the assembling efficiency of the raw material.

However, if the depth of the pelletizer pan increases above a certain value, small particles and coarse particles are mixed with each other inside the pelletizer pan, resulting in uneven segregation of raw materials. Therefore, raw materials that are not sufficiently assembled are mixed with raw materials of large particle size and easily discharged to the outside. Therefore, the effect of assembly due to extended residence time is not great.

5, the first pelletizer pan 10 and the second pelletizer pan 50 are inclined at a predetermined angle with respect to the ground for smooth discharge of the assembled raw material. As for the angle (alpha) which the 1st pelletizer pan 10 and the 2nd pelletizer fan 50 make with the ground, 40 degrees-60 degrees are preferable.

In the embodiment of the present invention, when the first pelletizing pan 10 and the second pelletizing pan 50 form an angle α of less than 40 °, the segregation of the raw material becomes uneven. On the contrary, when the angle (a) with the ground (e) exceeds 60 °, the residence time in the pelletizer decreases and the assembly effect is lowered.

FIG. 7A illustrates the droplet ratio of the pelletizer pan according to the change of the tilt of the pelletizer pan, and FIG. 7B illustrates the raw material residence time inside the pelletizer pan according to the change of the tilt of the pelletizer pan. When the finely divided raw material is continuously supplied to the pelletizer at a constant speed, there is a tendency as shown in Figs. 7A and 7B, although there is a difference in degree depending on the characteristics of the raw material and the operating conditions of the pelletizer pan.

The smaller the slope of the pelletizer pan, the less raw material assembled outside the pelletizer. This increases the spot rate at which the pelletizer pan holds the raw materials. In this case, as shown in FIG. 7B, the residence time in the pelletizer pan may be increased, thereby improving assembly performance. However, if the inclination of the pelletizer pan is too small, the segregation of the raw material inside the pelletizer pan becomes uneven so that the less granulated particles are mixed with the coarse particles and discharged to the outside of the pelletizer pan. Therefore, the assembly efficiency is deteriorated.

8A to 8E sequentially show a process in which the flow characteristics of the finely divided raw material change as the rotation speed of the pelletizer pan increases. In the drawings, the rotational speeds are represented by n1, n2, n3, n4 and n5. At this time, n4 represents the rotation speed of 0.8 times the critical rotation speed, and n5 represents the rotation speed of the critical rotation speed or more.

As shown in Figs. 8A to 8E, as the rotation speed of the pelletizer pan increases to the critical rotation speed, the area in which the fine powder flows inside the pelletizer pan gradually increases to the top of the pelletizer pan.

However, as shown in FIG. 8E, when the number of revolutions of the pelletizer fan increases above the critical number n5, the fine raw material rotates together with the pelletizer fan while the fine powder is attached to the wall. In this case, since the flow of raw materials hardly occurs, the granulation efficiency is lowered.

The number of revolutions of the pelletizer fan due to the increase in the number of revolutions of the pelletizer pan is called the critical revolution. According to Wolfgang Pietsch (size enlargement by agglomeration, John Wiley & Sons, 1991), It depends on the inclination and diameter of the fan and is represented by Equation 2 below.

Critical speed = 42.3 sinβ / D [D: diameter, β: tilt of fan (angle)]

Therefore, the general pelletizer operation is operated below the critical speed. The rotation speed is generally 0.8 times (n4) of the critical speed, although it depends on the angle of repose of the raw material.

9 shows a process of assembling the raw materials using the pelletizer 100 according to an embodiment of the present invention. First, the first storage bin 200 supplies the finely divided raw material 120 that is the target of the selective assembly 700. In this case, the finely divided raw material 120 supplied from the first storage bin 200 may include high crystal water ore such as marra mamba ore, ore, or dust generated in the steelmaking process.

The fine powder raw material 120 supplied from the first storage bin 200 is mixed by adding water in the high speed stirring mixer 300. The mixed fine powder raw material 120 is transported to the pelletizer 100 and assembled.

On the other hand, the second storage bin 400 supplies the remaining granulated raw material 140. The granulated raw material 140 is mixed in the primary mixer 500 and the secondary mixer 600. In this case, the finely divided raw material 120 which has undergone the selective granulation 700 is mixed with the granulated raw material 140.

The granulated fine powder may be supplied in front of the primary mixer 500, between the primary mixer 500 and the secondary mixer 600, or after the secondary mixer 600. FIG. 9 shows that the finely divided raw material is supplied between the primary mixer 500 and the secondary mixer 600 as an example.

Hereinafter, the present invention will be described in more detail through experimental examples. These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.

Experimental Example

Using a specific iron ore having a small particle size as a raw material, it was assembled using a conventional pelletizer and a pelletizer according to an embodiment of the present invention.

First, a certain amount of iron ore was placed in a high speed stirring mixer. Water was added to the high speed agitation mixer at about 10% by weight of iron ore for stirring. After the addition of water, the high speed stirring mixer was rotated to stir the iron ore. The stirred iron ore was charged into the hopper at the top of the raw material feeder and then fed to the pelletizer at a rate of 1.15 kg / min. Iron ores were assembled using a pelletizer. The specifications of the pelletizer differ depending on the experimental example and are as follows.

Experimental Example 1

The diameter of the 1st pelletizer pan was 600 mm, and the depth was 60 mm. In addition, the diameter of the 2nd pelletizer pan was 500 mm, and the depth was 50 mm. The distance between the first pelletizer pan and the second pelletizer pan was about 30 mm. In addition, the angle that the pelletizer fan makes with the ground was 47.5 °, and the rotation speed was kept constant at 22 RPM.

Experimental Example 2

The diameter of the second pelletizer pan was 450 mm, and the depth was 45 mm. The remaining specifications of the pelletizer are the same as in Experimental Example 1.

Experimental Example 3

The diameter of the second pelletizer pan was 400 mm, and the depth was 40 mm. The remaining specifications of the pelletizer are the same as in Experimental Example 1.

Experimental Example 4

The diameter of the second pelletizer pan was 350 mm, and the depth was 35 mm. The remaining specifications of the pelletizer are the same as in Experimental Example 1.

Comparative example

A pelletizer with only one pelletizer pan was used. The diameter of the pelletizer pan was 600 mm and the depth was 60 mm.

Table 1 shows the results of measuring the residence time and the assembly index of the pelletizer according to the above Experimental Example 1 to Experimental Example 4 and Comparative Example.

Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Comparative example Diameter ratio of the second pelletizer pan 0.83 0.75 0.67 0.58 _ Dwell time (sec) 280 253 209 180 165 Assembly index (GI1.0), (%) 45 50 48 41 30

Here, the diameter ratio of the second pelletizer pan means the ratio of the diameter of the second pelletizer fan to the diameter of the first pelletizer fan. As shown in Table 1, the raw material residence time of the pelletizer according to the experimental example of the present invention was longer than the raw material residence time of the pelletizer of the comparative example according to the prior art. However, the smaller the fan, the shorter the residence time and the lower the assembly index.

In Experimental Example 1, in which the diameter ratio of the second pelletizer pan was the largest, a substantial portion of particles falling downward from the second pelletizer pan jumped out of the first pelletizer pan. In addition, particles falling on the first pelletizer pan were also discharged to the outside immediately after mixing with the raw material of the coarse particles flowing. Therefore, the assembly efficiency does not appear to be significantly improved.

On the other hand, in Experimental Example 4 in which the diameter ratio of the second pelletizer fan is the minimum, since the assembly index is as small as 41%, it was found that the diameter of the second pelletizer fan should be increased.

Therefore, the diameter of the second pelletizer pan was appropriately about 0.67 to 0.75 times the diameter of the lower fan. This can be seen from Experimental Example 2 and Experimental Example 3.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

As described above, according to the present invention, a space for increasing the size of the pelletizer pan is not required, and the pelletizer pan can be used without changing the slope, depth, and feed rate of the raw material of the pelletizer pan. The residence time of the raw material can be increased to improve the assembly efficiency.

In addition, since the pelletizer undergoes two granulation processes, the particle size and strength of the granulated particles are increased.

In addition, in the case of supplying and assembling raw materials of other components such as fuel and subsidiary materials to the lower first pelletizer pan, fuel or subsidiary materials are coated on the surfaces of the granulated assemblies assembled in the upper second pelletizer pan. The internal and external composition of the pseudo-particles is changed to improve the combustibility of the fuel and to control the reactivity of the sintering.

Claims (9)

First pelletizer pan, A connecting shaft formed at a center of the first pelletizer fan in a vertical direction of the first pelletizer fan, and A second pelletizer fan which forms a concentric circle with the first pelletizer fan and is coupled to the first pelletizer fan by the connecting shaft. Pelletizer for finely divided raw material comprising a. The method of claim 1, A pelletizer for assembling fine raw materials, wherein the diameter of the second pelletizer pan is smaller than the diameter of the first pelletizer pan. The method of claim 2, The diameter of the second pelletizer pan is 0.67 times to 0.75 times the diameter of the first pelletizer pan pelletizer for assembling the raw material. The method of claim 1, A pelletizer for assembling fine raw materials, wherein the depth of the second pelletizer pan is smaller than the depth of the first pelletizer pan. The method of claim 4, wherein The depth of the second pelletizer pan is 0.1 to 0.14 times the diameter of the second pelletizer pan pelletizer for assembling the raw material. The method of claim 1, The connecting shaft has a pelletizer for assembling fine powder having a length of at least 0.07 times the diameter of the second pelletizer pan. The method of claim 1, The first pelletizer and the second pelletizer pan is a pelletizer for assembling the raw material to form an angle of 40 ° to 60 ° with the ground. The method of claim 1, The connecting shaft is a pelletizer for fine powder raw material assembly is formed in a cylindrical shape. The method of claim 1, The fine powder is pelletizer for fine powder raw material assembly containing iron ore.

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