JPH02221332A - Method for pelletizing sintered raw material - Google Patents

Abstract

PURPOSE:To produce rigid minipellets having a desired range of grain size by mixing a compaction medium into a sintered raw material, using a cylinder exciter to optimize the gradient and exciting force of the cylinder shaft and adjusting the space factor of the raw material. CONSTITUTION:The compaction medium in a vessel is oscillated and rolled. The sintered material is charged into the space between the mediums, compacted, plasticized and kneaded into dense flakes. The flaked sintered material is charged into the pelletization exciting cylinder. The cylinder shaft is inclined at a gradient of + or -10 deg., the exciting force is adjusted to control the space factor of the material in the cylinder to 8-20%, and the material is oscillated, rolled and briquetted. By this method, rigid minipellets are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a sintering raw material granulation method in which iron ore or the like is fed to a DL type sintering machine and the sintered ore is sintered.

More specifically, the present invention relates to a method for granulating a sintered raw material in which a sintered raw material having a desired particle size is obtained by adjusting the space factor within the granulation excitation cylinder.

[Prior Art] FIG. 14 is an overall flow sheet of a conventional DL type sintering machine. The sintering raw material blending tank 1 stores sintering raw materials (fine ore 1, pentashite, coke powder, quicklime, and return ore), which are quantitatively cut out by a constant feeder 2 installed at the bottom of the blending tank. After that, they are stacked and blended in multiple layers on the belt conveyor 3. The raw materials are mixed in drum mixer 4.
It is mixed and granulated by adding 4 to 5% water. The granules are conveyed to the ore feed hopper 14, and then transferred to the lower drum feeder 15J.
The ore is charged into the pallet 18 of the DL type sintering machine 17 via the ore feed shade 16. Thereafter, the ignition burner 19 ignites the coke powder in the raw material, and sintering progresses.

In this case, fine iron ore (hereinafter referred to as PF) is also used, in which 60% or more of the particles are less than 60 μm. P.F.
If a large amount of (10% or more based on the main raw material) is used, ventilation of the sintered bed will be inhibited and productivity will decrease. Another disadvantage is that a large amount of binder (quicklime, slaked lime, etc.) is required to improve ventilation, and the cost of the binder increases.

In order to solve the above problems, PF (approximately 60%) and the core raw material (return ore or iron ore 6 approximately 40%) are pre-granulated using a drum mixer or disc pelletizer and then used as normal sintering raw materials. A nuclear granulation method for PF is proposed, in which the mixture is mixed with PF and charged into a drum-type mixer for mixed granulation (Tetsu to Hagane: vo
l, 71. 10 (1985) Granulation of F sintering raw material and its role j7), in this case, since a core raw material is required, the capacity of the mixer is 1.4 times larger with the same -PF blending ratio. The disadvantage is that the equipment cost is high.

Yet another method is to use normal sintering raw materials (60% fine ore).
) is blended with approximately 40% PF, and fed to a disk-type pelletizer for mixing and granulation to form pellets of 5 to 10 mm. A method has been proposed in which fine coke is then added and the outer periphery of the pellets is coated with outer coke, which is transported to an ore feed hopper and sintered (Tetsu to Hagane: Vol. 73, Fk
Lll (1987) Basic research on manufacturing conditions and quality evaluation of new agglomerated ore for blast furnaces J).

A disadvantage of this method is that the green balls have a low apparent density and a low crushing strength, so they are easily broken during the transportation process to the sintered bed, which impedes ventilation of the bed. Moreover, the average particle size of the finished product is as large as 8 to 10 mm, and exterior coke is required. Furthermore, if the exterior coke does not adhere uniformly to the outer periphery of the pellets, there is a disadvantage that the inside of the ball remains unmelted and tends to become a single pellet or return ore during the crushing process.

On the other hand, although it is an old technology, the hot grinding and kneading granulation method (Japanese Patent Publication No. 43-6256) is known, in which the raw materials are ground using a ball mill, rod mill, or other hot grinding and kneading machine.
After adjusting the moisture content and mixing, the raw pellets are granulated using a vertical type, one cylinder type, or other type of granulator.

This method accomplishes the conventional wet or dry grinding process and the moisture adjustment mixing process in a single step in a wet state.

This method utilizes the rolling of a rod or ball caused by the rotation of a drum, so the production volume is small considering the equipment required, and the power consumption is high (currently, it is not economical).

[Problem to be Solved by the Invention J] In view of the above-mentioned circumstances, the present inventors mixed a consolidation medium into the sintering raw material and subjected it to strong circular vibration to achieve high efficiency, high production volume, and excellent quality. By using a cylindrical shaker for granulation to perform vibration-consolidation plasticization and kneading under appropriate conditions, it is possible to form strong mini-pellets in the desired particle size range. It was discovered that high efficiency production is possible.

An object of the present invention is to provide a method for manufacturing strong mini-pellets by adjusting the space factor of the vibrating cylinder for granulation in such a granulation method.

[Means for Solving the Problems J] The present invention vibrates and rolls a large number of compaction media housed in a container when granulating the sintering raw material to be supplied to a DL sintering machine. The sintering raw material is charged into the gap between the moving consolidation media and is consolidated, plasticized, and kneaded.

A dense flake-like sintered raw material is formed, and then the flake-like sintered raw material is charged into a vibrating cylinder for granulation, and the cylinder axis is tilted at an inclination within a range of ±10 degrees, and the sintered raw material is heated. The feature is that the space factor of the raw material in the granulation cylinder is adjusted to 8 to 20% by adjusting the vibration force, and the granulation raw material is agglomerated by vibration and rolling to granulate one strong mini-pellet. shall be.

[Action J: By applying a strong excitation force that causes a circular motion to the consolidation medium housed in a container, the consolidation medium rolls in the same rotation direction, and the surfaces of adjacent consolidation media move in relative opposite directions. This gives consolidation, shearing, rolling, crushing, kneading, and cross-talk effects to the particles existing between the consolidation medium, squeezing out the internal moisture of the particles and leveling out the surface moisture, resulting in a particle group. becomes flakes and becomes compacted and plasticized.

This will be explained with reference to FIG. As shown in Figure 12 (a), when a fine powder raw material with a certain moisture content is stored in a container and an excitation force is applied in the direction of compressing it, the density of the fine powder in the container increases. Are known. At this time,
The filling state of the particles changes depending on the water content ratio of the fine powder raw material in the container and the magnitude of the applied vibration energy, and the density increases according to this filling state. The graph in FIG. 12 shows this.

When the moisture content of the fine powder raw material is low, air gaps exist between the particles of the powder, and the powder is in the state of a dry mixture. When the water content of the fine powder raw material is increased and it is vibrated, the water is uniformly spread over the surface of the particles, the air gaps are eliminated, and the entire granule becomes sticky and plasticized.
The dry density of the fine powder raw material approaches a curve with zero porosity.

When the water content further increases, the powder becomes a slurry. The plastic state, which has less moisture than this slurry state and has the least air voids, is called the capillary region, where the powder has the highest dry density and is in the form of dense flakes.

This capillary region powder can be obtained by applying vibration compression with the most appropriate water content ratio and appropriate energy depending on the properties of the particles.

The present invention is a method for granulating a sintering raw material using this principle of the process, in which powder that has been turned into flakes in the capillary region is first processed by vibration consolidation plasticization and kneading, and the powder that has been turned into flakes is processed. The material is rolled and granulated.

Therefore, the appropriate water content ratio and optimum excitation force according to the characteristics of the fine powder raw material are applied to the fine powder raw material, so that the water droplets on the surface of each particle are uniformly dispersed on the particle surface, and a thin water film is stretched over the particle surface. Then, the porosity due to air between each particle is reduced to form a dense packing, and the filling state becomes a capillary region, forming a densely packed compacted and plasticized flake.

The amount of water added may be the difference between the water content of the raw material and the optimum water content ratio for granulation, and is 0 to 2%. That is, when the entire amount of the sintered raw material having a wide particle size range is subjected to vibration consolidation, the optimum water content ratio is adjusted to 5 to 7% compared to the moisture content of the raw material of 5 to 6%. In addition, when granulating only PF, PF is 8 to 11%.
The optimum moisture content is 9 to 12%.

Next, FIG. 13 shows the apparent density and crushing strength of the granules when the excitation force of the consolidation plasticization kneader was varied.

Further, the apparent density and crushing strength of the granulated product of the comparative example are also shown in FIG. 13.

The bulk density of the raw material before granulation was 2.5 g/cm 3 , and the dry apparent density of the granulated product granulated with a disk pelletizer was 3.1. On the other hand, in the examples, the apparent density was very dense, ranging from 4.4 to 5.6, depending on the vibration acceleration.

In addition, the crushing strength of the granules (wet balls) granulated with a disc beletizer was about 70 g/piece, whereas in the examples, the crushing strength was about 130 to 150 g depending on the vibration acceleration.
/ piece, which was extremely strong.

From Figure 13, if the excitation force of the consolidation plasticization kneader is less than 3g, the effect of consolidation granulation is small, and if it exceeds 10g, it is saturated, and the appropriate range of the excitation force of the mixer is 3g-10g. I understand.

Next, in the granulation process, when this compacted and plasticized raw material is subjected to rolling motion by strong vibration, the packing density increases.1 Moisture seeps out to the surface and adhesion due to this moisture occurs.

Grain size growth occurs.

In this case, the throughput of the granulator is shown in Figures 6 and 7.
There is a relationship shown in the figure, and the relationship between the processing capacity of the granulator and the internal capacity of the granulation cylinder is approximately expressed by the following equation.

Qv=a・γ・・・・−(1)Q=QT
-V=a・γ・V (2) However, Q: Processing capacity (t/h) Q: Unit processing capacity (,kg/i!,・h) γ: Bulk specific gravity (t/h) /rr?) V: Internal volume of the cylinder for granulation (I2) a: Proportionality constant. Substituting V=D”・L and L/D=3.5 into the above formula (2) and rearranging, Q= a・γ・−・D2・L πX, b.

It is.

Residence time (min) Drum length (m) Angle of repose of raw material) Drum inner diameter (m) Drum tilt angle) Rotational speed (r p m) C: Coefficient Therefore, the space factor Φ is υ d ・It can be expressed as π·Lr, and the space factor Φ is a function of the rotation speed and inclination angle of the granulation cylinder. By adjusting either or both of the rotational speed and the inclination angle, the space factor of the raw material within the granulation cylinder is adjusted, and strong mini-pellets are granulated.

A suitable space factor is 8 to 20%. If the space factor is less than 8%, the adhesion of particles to each other due to rolling motion will not be sufficient and the size of the granulated particles will be insufficient. Moreover, if it exceeds 20%, the size of the granulated particles becomes too large.

FIG. 8 shows the relationship between the vibration acceleration of a horizontal cylindrical vibratory granulator and the space factor with respect to the cylinder inclination. This figure is a graph when the amplitude of vibration is kept constant (7 mm). In order to set the space factor to an optimal value of 8 to 20%, the acceleration of the vibration should be adjusted to 3 to 6 g, and the inclination of the cylinder should be adjusted within the range of ±10 degrees.

If the acceleration of vibration is less than 3 g, the particle size of the pellets to be granulated will be small, and if the acceleration is more than 6 g, the particle size will become too large and cannot be used6. Therefore, the excitation force should be in the range of 3 to 6 g.

Conversely, when the excitation force is in the range of 3 to 6 g, the space factor is 8 to 6 g.
The adjustment range of the inclination angle to obtain 20% may be ±10 degrees from FIG.

[Example] Fig. 2 shows a flow sheet of a sintering operation in an example of the present invention, in which the sintered mixed raw material conveyed from the sintered raw material blending tank 1 on the belt conveyor 3 is subjected to vibration consolidation plasticization. Kneading device 30
Consolidation, plasticization, kneading, and then vibration granulation device 4
0.

The mini-pellets granulated here are transported to the ore feed hopper 14 and charged into the pallet 18 of the DL type sintering machine 17 via the drum feeder 15 and the ore feed chute 16.

Figure 3 shows the above-mentioned consolidation plasticization kneading device 30 and vibration granulation device 4.
FIG. 4 is a side view of an example of a vibration granulator, and FIG. 5 is a side view of a vibration granulator different from FIG. 4.

The apparatus shown in FIG. 4 has a horizontal cylindrical drum 41 whose raw material supply side is supported by a vertical shaft 45, and a rocking vibrator 46 that horizontally rocks the drum 41 on the raw material discharge side. A tilting device 48 placed on the frame 47 and tilting the frame 47. A bin support bracket 49 is provided.

Another vibration granulating device 40 shown in FIG. 5 is a device in which a drum 41 is supported by a spring 43 and vibrators 42 are mounted on both sides of the drum 41. This vibrator is synchronized with the left and right sides, and applies circular motion vibration to the drum 41, and gives rolling motion to the sintered raw material in the drum 41 to granulate it. The entire device is placed on a frame 47 in the same way as the device shown in FIG.
A tilting device 48 and a bin support bracket 49 are provided.

FIG. 1 is a longitudinal cross-sectional view of a cylindrical vibrating granulator, (a
) When it is horizontal, (b) When it is tilted forward with respect to the raw material transfer direction, that is, when the inclination angle θ is negative, (C
) Indicates a case where the inclination is opposite to the direction in which the raw material is transferred, that is, a case where the inclination angle θ is positive. The space factor of the sintered raw material in the granulator 40 decreases in the case of forward tilt (b),
It increases in case of reverse slope (C). Further, at the same slope, as the excitation force increases, the space factor decreases. This relationship is
This has already been explained with reference to FIG.

The particle size distribution of the sintered raw material granulated using the apparatus shown in Figure 3 is as follows:
FIG. 9 shows a comparison with the particle size distribution of a sintered raw material granulated using a conventional drum mixer.

In addition, the crushing strength and apparent specific gravity of the dry balls of the granulated mini-pellets in response to the acceleration of vibration during the consolidation, plasticization, and kneading process are shown in Figure 10 in comparison with particles granulated by a conventional disk pelletizer. .

Furthermore, FIG. 11 illustrates the blending ratio of PF and the sintering production rate by comparing the method of the present invention with the conventional granulation method using a drum mixer.

From FIGS. 9 to 11, it is clear that by the granulation method of the present invention, it is possible to easily produce mini-pellets that are dense, have a good particle size distribution, and have high strength. Also, P.F.
Since the blending ratio can be increased, a large amount of low-cost raw materials can be used, and the amount of binder can be reduced, it is possible to produce low-cost sintered raw materials.
Furthermore, it is clear that the sintering production rate is also improved.

[Effect of the invention J According to the present invention, the powder particles in the mini pellets are packed densely, the apparent density and crushing strength of the green balls are improved, and the yield of 2 to 5 mm is further improved. This improves air permeability in the sintered bed.

Therefore, it is possible to use multiple PF mixtures, improve sintering productivity, and expect power savings for the main exhaust fan.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view illustrating changes in space factor due to changes in the inclination angle of the vibrating granulator according to the present invention, and FIG. 2 is a flow sheet showing the entire sintering process of an embodiment of the present invention. Fig. 3 is a perspective view of an example of a vibratory compaction plasticization kneader and a vibratory granulator, Fig. 4 is a side view of an example of a vibratory granulator, and Fig. 5 is another vibratory granulator. Fig. 6 is a graph showing the relationship between the bulk specific gravity of the sintered raw material and the unit processing capacity, and Fig. 7 is the ratio of the bulk specific gravity of the sintered raw material to the capacity of the granulator/capacity of the kneader. Figure 8 is a graph showing the relationship between the inclination angle and vibration acceleration of the granulator and the space factor, Figure 9 is a graph showing the particle size distribution of the manufactured mini pellets, and Figure 10 is the consolidation ratio. A graph showing the vibration acceleration of the plasticizing kneading device, the crushing strength of the granulated particles, and the apparent density. Figure 11 is a graph of the PF blending ratio and sintering production rate. Figure 12 is a graph of the process of the present invention. An explanatory diagram for explaining the principle, FIG. 13 is a graph showing the apparent density and crushing strength of the finished products of Examples and Comparative Examples, and FIG. 14 is a flow sheet of a conventional sintering process. 30--Vibration consolidation plasticization kneading device 40--Vibration granulation device

Claims (1)

[Claims] 1. When granulating the sintering raw material to be supplied to the DL sintering machine, a large number of consolidation media are vibrated and rolled, and the sintering raw materials are loaded into the gaps between the rolling consolidation media. The flaky sintered raw material is then put into a vibrating cylinder for granulation, and the slope of the cylindrical axis of the cylinder is set to ±10. The space factor of the raw material in the granulation cylinder is adjusted to 8 to 20% by adjusting the excitation force and the raw material is agglomerated by vibration and rolling to form strong mini-pellets. A method for granulating a sintered raw material, the method comprising granulating a sintered raw material.