JP2009287122A - Method for pelletizing fine-powdery raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for pelletizing fine powdery raw material which is suitable to the pelletization of sintering raw material mainly containing the fine powder, and can produce the pellet produced with the intended size distribution and can improve the yield as higher in comparison with the conventional method. <P>SOLUTION: The method produces the pellet by pelletizing the sintering raw material 10 containing ≥60 mass% powder having ≤250 μm particle diameter, with a drum-mixer 12 having smooth inner surface 11. Under stational state of the drum-mixer 12, a lamination thickness h1 of the sintering raw material 10 stored on the bottom part 13 in the drum-mixer 12 is made to be ≤30 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a granulation method of a fine powder material that is suitable for granulation of a sintered raw material mainly composed of fine powder (mainly iron ore raw material) and that can produce a granulated product having a target particle size distribution.

Blast furnace raw material sintered ore (hereinafter also referred to simply as “sintered ore”) is laminated on various iron ores with, for example, a sintering raw material containing lime and coal mixed in a sintering machine. After ignition, it is obtained by sucking air below the laminated sintered raw material to ventilate the sintered raw material and firing the sintered raw material.
Conventionally, the sintering raw material is granulated in advance for the purpose of maintaining good air permeability in the sintering raw material during the firing and maintaining high productivity of the sintered ore by the sintering machine. This granulation is generally performed by using a cylindrical drum mixer and rolling together a sintered raw material having a wide particle size distribution from fine powder to coarse particles around the coarse particles that become the core. A method of attaching fine powder is used. Therefore, conventionally, operation conditions for ensuring such rolling granulation have been studied.
For example, in Patent Document 1, the space factor of the raw material in the drum mixer is kept at 8 to 18%, and in Patent Document 2, the space factor is 9% or more and the fluid number is 12.8 × 10. It is disclosed that the rolling state of the sintered raw material can be secured satisfactorily by setting it to ⁻³ or more.

Here, the space factor is a numerical value indicating the area ratio of the sintered raw material in the cross-sectional area of the drum mixer. The fluid number is the ratio of the inertial force acting on the sintering raw material and the gravity, and the balance between the scraping force applied to the raw material by the rotation of the drum mixer and the gravity that guides the sintered sintering raw material downward. Thus, it is an index representing that the rolling state of the sintering raw material in the drum mixer is determined. In addition, when the diameter (inner diameter) of the drum mixer is D, the rotational peripheral speed of the drum mixer is u, the rotational speed of the drum mixer is N, and the gravitational acceleration of the sintering raw material is g, the Froude number Fr is expressed by the following equation. Is done.
Fr = u ² / D / g = D × N ² / g
Further, in Patent Documents 1 and 2, by adjusting the space factor of the sintered raw material of the drum mixer within the normal rolling region, the rolling state of the sintered raw material becomes good, whereas the space factor is If it is smaller than this (slip area), the sintering raw material will slip against the inner surface of the drum mixer, while if the space factor is large (jumping area), the sintering raw material in the drum mixer will jump. Thus, it is shown that good granulation cannot be performed.

Japanese Patent Laid-Open No. 52-101602 JP-A-53-141104

However, as described above, the conventional granulation conditions can be applied to a sintering raw material in which coarse particles as a core and fine powder adhering to the periphery thereof are mixed in the same weight ratio. For this reason, as described above, in the situation where the high-quality iron ore raw materials that have been used in the past have been depleted and the ratio of the iron ore raw materials having a high crystallization water content and a large amount of fine powder has increased, Not applicable. This is because the sintering raw material containing a large amount of fine powder is difficult to roll because there are few coarse particles as the core, and the specific surface area is large because it is mainly fine powder, and a large amount of moisture is required for granulation. This is due to the fact that the adhesion between the raw materials becomes strong, and the sintered raw material becomes difficult to roll.
As described above, it has been found that the sintered raw material mainly composed of the fine powder as the subject of the present invention causes the slip phenomenon to cause the slip phenomenon even under the conventional appropriate conditions, and the stable rolling cannot be ensured. That is, the rolling phenomenon of the sintering raw material mainly composed of fine powder was found to be significantly different from the conventional rolling phenomenon, and as a result, the sintering raw material mainly composed of fine powder was stably rolled and granulated. The need to establish new granulation technology has arisen.

The present invention has been made in view of such circumstances, and is suitable for granulation of a sintering raw material mainly composed of fine powder, and can produce a granulated product having a target particle size distribution, and its yield (yield). It is an object of the present invention to provide a method for granulating a fine powder raw material that can be improved over conventional methods.

The granulation method of the fine powder raw material according to the first invention that meets the above-mentioned object rolls and granulates the sintered raw material charged from one side, moves the produced granulated material to the other side, and discharges it. By using a drum mixer that continuously granulates the sintered raw material, a sintered raw material containing 60% by mass or more of particles having a particle size of 250 μm or less is granulated with the drum mixer having a smooth inner surface. A method for producing a granule, comprising:
When the drum mixer is in a stationary state, the lamination thickness of the sintering raw material accumulated at the bottom of the drum mixer is set to 30 mm or less.

The granulation method of the fine powder raw material according to the second invention that meets the above-mentioned object rolls and granulates the sintered raw material charged from one side, moves the produced granulated material to the other side, and discharges it. By using a drum mixer that continuously granulates the sintering raw material, a plurality of slip suppression members that suppress the sliding of the sintering raw material are provided so as to protrude from the inner surface of the drum mixer, and the particle size is 250 μm or less. A method for producing a granulated product by granulating a sintering raw material containing 60% by mass or more of particles with the drum mixer,
The protrusion height of the slip suppression member from the inner surface of the drum mixer is set to 30 mm or less, and the lamination thickness of the sintered raw material accumulated at the bottom of the drum mixer in the stationary state of the drum mixer is set to the slip suppression. The protrusion height of the member is exceeded and is 300 mm or less.

In the granulation method of the fine powder raw material according to the first and second inventions, it is preferable that the water content of the granulated product is in the range of 8 mass% to 11 mass%.

Since the granulation method of the fine raw material according to claims 1 to 3 prescribes the lamination thickness of the sintered raw material mainly composed of the fine powder to be put in the drum mixer, when granulating the sintered raw material using the drum mixer In addition, it is possible to suppress the sliding phenomenon of the sintering raw material and the jumping phenomenon of the sintering raw material with respect to the inner surface of the drum mixer, and it is possible to efficiently produce a granulated product having a required particle size. Moreover, the yield of this granulated material can also be improved compared with the past.
The granulation method of the fine powder raw material according to claim 2 and claim 3 dependent thereon is provided with a slip suppression member for suppressing the slip of the fine powder sintering raw material on the inner surface of the drum mixer, and the protrusion of the slip suppression member Since the height is regulated, more sintering raw materials can be granulated than when there is no slip suppression member, and the productivity of the granulated product can be improved.
In particular, the granulation method of the fine powder raw material according to claim 3 regulates the moisture content of the granulated product to be produced, so that the moisture content of the granulated product can be adjusted to an amount suitable for the granulation of the sintered raw material. The yield of the granulated product having the required particle size can be further improved.

It is a front sectional view of the drum mixer used for the granulation method of the fine powder raw material concerning one embodiment of the present invention. It is explanatory drawing which shows the relationship between the granulation conditions and granulation condition in a prior art. (A) is explanatory drawing which shows the rolling state of the raw material in which a coarse particle and fine powder are mixed, (B) is explanatory drawing which shows the rolling state of the raw material which has fine powder as a main body. It is explanatory drawing which shows the relationship between the lamination thickness of an iron ore raw material, the diameter of a drum mixer, and the yield of the granulated material of a target particle size. It is explanatory drawing which shows the lamination | stacking state of the iron ore raw material in a drum mixer. It is explanatory drawing which shows the relationship between the lamination thickness of the iron ore raw material in a drum mixer, and the granulation property of a raw material. It is a front sectional view of a drum mixer used for a granulation method of a fine powder raw material according to another embodiment of the present invention. It is explanatory drawing which shows the relationship between the lifter height and the lamination thickness of an iron ore raw material, and the yield of the granulated material of a target particle size.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIG. 1, the method for granulating a fine raw material according to an embodiment of the present invention includes a sintering raw material 10 containing 60% by mass or more of particles having a particle size of 250 μm or less, and a cylindrical inner surface 11 that is smooth. This is a method for producing a granulated product by granulating with a drum mixer 12, and setting the lamination thickness h <b> 1 of the sintering raw material 10 accumulated on the bottom 13 in the drum mixer 12 to an appropriate range when the drum mixer 12 is stationary. . Here, the inner surface 11 of the drum mixer 12 being smooth means that the inner surface of the cylinder is smooth without any irregularities. The laminated thickness h1 of the sintered raw material 10 is the static state of the drum mixer 12, that is, when the sintered raw material 10 is placed on the bottom 13 of the drum mixer 12 so that the upper surface is flat. It means the part where the lamination thickness becomes the thickest. This lamination thickness h1 is an average value of the lamination thicknesses in the longitudinal direction of the drum mixer 12. This will be described in detail below.

First, the sintering raw material 10 is put into the drum mixer 12, and water and a binder are further put therein, and these are granulated.
Here, the sintered raw material 10 contains 60% by mass or more of particles having a particle size of 250 μm or less, and mainly comprises an iron ore raw material (for example, more than 50% by mass of the sintered raw material, more preferably 60% by mass to For example, return ore (about 20% by mass), which uses the fine powder portion of sintered ore as a sintering raw material again, fuel such as fine coke (less than 5% by mass, about 4% by mass) Degree), and auxiliary materials (about 10% by mass) including quicklime and serpentinite.
Further, the iron ore raw material constituting the sintered raw material contains 60% by mass or more of particles having a particle size of 250 μm or less, as in the case of the sintered raw material. An adjusted raw material, a raw material obtained by separating only fine powder by sieve screening, and a pulverized raw material can be used.
This iron ore raw material is, for example, one or more of limonite (Fe ₂ O ₃ .nH ₂ O), magnetite (Fe ₃ O ₄ ), and hematite (Fe ₂ O ₃ ). Examples of limonite include maramamba ore (local brand: West Angelus), pisolite ore (local brand: Yandhi, Loeb River), and high phosphorus block man ore. In addition, as composition of an iron ore raw material, what mix | blended the sieving powder after sieving a block ore and the imported iron ore (for example, maramamba ore) with many fine powders in the ratio of 1: 6, for example. is there.

As the sintering raw material, the raw material containing 60% by mass or more of particles having a particle size of more than 0 μm and not more than 250 μm was targeted when the raw material having such a structure was granulated by a conventional method, as described above. This is because granulation becomes incomplete.
From this, in the present embodiment, a firing containing particles having a particle size of 250 μm or less, preferably 220 μm or less, more preferably 200 μm or less is 60% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more. The kneading material is the target of kneading. Note that the upper limit of the amount of fine powder is not specified because all fine powder may be used, and the sintering raw material may be, for example, 100% by mass of particles having a particle size of 1 mm or less. .
As described above, in the present embodiment, since the sintering raw material mainly composed of fine powder is used, the sintering raw material can further include a fine-iron-containing raw material. As this iron-containing raw material, for example, any one or two of dust (kneaded dust or dust dust) and pellet raw material (also referred to as pellet feed) can be used. The particle size of the dust is about 100 μm or less, and the particle size of the pellet raw material is about 250 μm or less.

Since the binder contributes to improving the strength of the granulated product, an inorganic binder such as quick lime or limestone that has been conventionally used can be used. In addition, as the binder, for example, any one of an organic binder containing pulp waste liquid or corn starch (aqueous solution or colloidal form) and a dispersing agent (including an aqueous solution or colloid added with a dispersing agent) that promotes solid crosslinking Although 1 or 2 is preferably used, this and an inorganic binder may be used in combination. In addition, the addition amount of a binder may be about 1 mass% or less on the outside with respect to the amount of sintering raw materials.
Even if the above-described sintered raw material is simply granulated using the drum mixer 12, the target particle size distribution suitable for supply to a sintering machine (not shown) is 3 mm or more and 10 mm or less (hereinafter simply referred to as the target particle size). )) Cannot be obtained in a high yield (in this embodiment, 50% by mass or more). Therefore, in order to obtain a granulated product having a target particle size with a high yield, the following examination was performed.

As shown in FIG. 1, in the drum mixer 12, in order to continuously granulate the sintered raw material 10, the sintered raw material 10 is introduced from one side of the drum mixer 12, and is rotated in the rotating drum mixer 12. The granulated product is moved and granulated, and the produced granulated product is moved to the other side and discharged. Here, the lamination thickness h1 of the sintered raw material 10 in the drum mixer 12 is determined based on the feeding speed (supply speed) of the sintered raw material 10 to the drum mixer 12 and the residence time of the sintered raw material 10 in the drum mixer 12 ( It is determined by the rotational peripheral speed of the drum mixer 12 and the inclination angle from the inlet to the outlet of the drum mixer 12).

At this time, the area ratio of the sintered raw material 10 to the cross-sectional area of the drum mixer 12 is the space factor. In addition, since the inclination angle of the drum mixer is small (for example, 5 degrees or less), the space factor of the sintering raw material is substantially the same at any location in the longitudinal direction of the drum mixer.
This space factor is preferably as high as possible when increasing the productivity of the granulated product by the drum mixer, but in order to perform good granulation, normal rolling of the sintered raw material can be ensured. It is necessary to set the region, that is, the normal rolling region. In addition, this normal rolling area is equivalent to the range of a space factor of about 8 to 18% in the granulating operation of the sintered raw material in which conventional coarse particles to fine powder are mixed.

As shown in FIG. 2, when the space factor is less than the normal rolling region, the raw material does not roll and the inner surface of the drum mixer is slid. On the other hand, when the raw material is excessive, the raw material jumps. Was known.
In this invention, since the sintering raw material which uses fine powder as a main component is used, it investigated in detail using the drum mixer for experiment how the rolling condition changed under the influence. As a result, using a drum mixer with a smooth inner surface, when the sintering raw material is laminated in the drum mixer so that the space factor of the sintering raw material is in the normal rolling region, the sintering raw material does not roll, The inner surface of the drum mixer was slid while being laminated.
For this reason, in order to roll the sintering raw material mainly composed of fine powder in the drum mixer, the space factor has to be considerably reduced as compared with the prior art. This is because granulation of a sintering raw material mainly composed of fine powder, it is necessary to increase the moisture level necessary for granulation as compared with the conventional method, but this increases the adhesion of the powder and increases the cohesion of the powder layer. Therefore, it is presumed that a larger force is required than before in order to break up and roll the powder layer.

Here, the particle size constitution of the raw material and the image of the rolling property of the raw material in the drum mixer will be described with reference to FIGS. 3 (A) and 3 (B). 3A is a rolling image of a raw material in which coarse particles and fine powder (fine particles) are mixed, and FIG. 3B is a rolling image of a raw material mainly composed of fine powder.
As shown in FIG. 3A, in the case of a raw material in which coarse particles and fine powder are mixed, the coarse particles are actively rolled by receiving a shearing force from the inner surface of the drum mixer, so that the powder including fine particles is also included. Since the fluidity of the whole bed is secured, it is considered that the rolling property of the raw material can be secured even with a relatively large space factor.
On the other hand, as shown in FIG. 3B, in the case of a raw material mainly composed of fine powder, the particles in the vicinity of the inner surface of the drum mixer roll because they receive a shearing force, but since the inertial force of each particle is small, The rolling power is difficult to be transmitted to the whole. On the other hand, since the specific surface area is relatively large, the amount of water required to wet the surface of the raw material increases, so that the adhesion between the raw materials increases, it becomes easier to agglomerate, and it is more difficult to roll. It is considered to be.

From the above, in order to ensure the rolling of the raw material, the stacking thickness of the raw material in the drum mixer is reduced in contrast to the increase in the adhesion between the raw materials with the pulverization of the raw material and the increase in the water content. By reducing, it is thought that it is necessary to relatively strengthen the rolling force for the raw material layer composed of fine powder and to pulverize the raw material layer. At this time, the laminated thickness of the raw materials tends to be slightly increased by increasing the rotational peripheral speed (number of rotations) of the drum mixer, that is, by increasing the Fr number.
Here, the result of investigating the influence of the scale of the drum mixer on the rolling of the raw material will be described with reference to FIG. In addition, since the main component of the sintered raw material is an iron ore raw material and the particle size distribution thereof is the same, the investigation was performed using the iron ore raw material as the raw material (FIGS. 5, 6, and 8 shown below also). The same). A drum mixer having a diameter of 0.55 m (●) and a diameter of 1 m (Δ) was used. Here, when the diameter of the drum mixer is 0.55 m, the rotation speed is 35 rpm and the granulation processing time is 2 minutes. When the diameter of the drum mixer is 1 m, the rotation speed is 20 rpm and the granulation processing time is For 2 minutes, by changing the charging speed of the iron ore raw material to the drum mixer variously, the laminated thickness h1 of the iron ore raw material was changed, and the granulated material having a water content of 9.5% by mass was produced. Moreover, evaluation was performed with the yield (target value: 50 mass%) of the granulated material provided with the target particle size finally obtained.

As apparent from FIG. 4, the yield of the granulated product was drastically reduced when the stacking thickness h1 of the iron ore raw material exceeded 20 mm regardless of the size of the drum mixer. This is because the iron ore raw material slip occurs on the inner surface of the drum mixer, and particularly when the lamination thickness h1 of the iron ore raw material exceeds 30 mm, the occurrence of the slip becomes remarkable, and the normal rolling of the iron ore raw material occurs. This is due to the fact that it cannot be secured.
Here, the grounds for determining the lamination thickness h1 of the iron ore raw material used instead of the sintered raw material regardless of the diameter of the drum mixer will be described with reference to FIGS.
FIG. 5 shows a laminated state of the iron ore raw material (sintered raw material 10) in a state where the drum mixer 12 is stopped, and the turning power of the iron ore raw material is the inner surface 11 of the drum mixer 12 with which the iron ore raw material comes into contact. From the area S, it can be considered that it is given to the iron ore raw material of volume V. That is, (V / S) indicating the balance between S and V is considered to determine the rolling state of the iron ore raw material (granulating property of the raw material). By increasing (V / S), the iron ore raw material It is assumed that there will be insufficient rolling power and a slip state will occur.

Moreover, it is clear from FIG. 6 that the balance between S and V (V / S) increases as the lamination thickness h1 of the iron ore raw material increases, and the iron ore raw material slips above a certain limit value. It is guessed that it enters. Further, even if the diameter of the drum mixer is different, the (V / S) with respect to the stacking thickness h1 of the iron ore raw material is substantially the same, so the stacking thickness h1 that becomes the slip limit may not depend on the diameter of the drum mixer. Explained.
From the above, when using a drum mixer 12 having a smooth inner surface 11 and granulating the sintered raw material 10 to produce a granulated product, the drum mixer 12 is stationary and placed on the bottom 13 in the drum mixer 12. The accumulated thickness h1 of the accumulated sintering raw material 10 is set to 30 mm or less. In addition, in order to further improve the yield of a granulated product having a particle size of 3 mm or more and 10 mm or less finally obtained, the lamination thickness h1 is preferably 25 mm or less, and more preferably 20 mm or less. On the other hand, as the lamination thickness h1 of the sintering raw material becomes smaller, the yield of the granulated product can be improved, so the lower limit is not specified, but considering the productivity of the granulated product, The lamination thickness h1 of the sintering raw material is preferably 5 mm or more, more preferably 10 mm or more.

Thus, by making the lamination thickness h1 of the sintering raw material thinner than before, the rolling of the sintering raw material mainly composed of fine powder can be carried out well, and the yield of the granulated product with the target particle size can be improved. However, from the viewpoint of the productivity of the granulated product, it is preferable to further improve the processing amount in the drum mixer. In order to increase the productivity of the granulated material, the drum mixer may be enlarged. However, when the inner surface of the drum mixer is smooth, even if the drum mixer is enlarged, the lamination thickness h1 of the sintered raw material is about 30 mm or less. Therefore, productivity cannot be greatly improved. Further, in order to increase the productivity of the granulated product, as described above, means for increasing the space factor of the sintered raw material is required, but even if the space factor is increased and (V / S) is increased. In order to avoid the slip of the sintering material, it is necessary to increase the frictional resistance between the inner surface of the drum mixer and the sintering material.
Therefore, as shown in FIG. 7, a plurality of lifters (an example of a slip suppression member) 17 that is provided on the inner surface 16 of the drum mixer 15 and suppresses the sliding of the sintering raw material 10 is used.

The lifter 17 has a thin plate shape, is provided so as to protrude toward the center of the drum mixer 15, and is provided perpendicular to the inner surface 16 of the drum mixer 15. The shape of the lifter is not limited to this, and the cross-sectional shape may be a concave shape, for example, and the bottom portion may be bolted to the drum mixer 15. The lifter may be provided to be inclined with respect to the inner surface of the drum mixer.
A plurality of lifters 17 are provided on the inner side of the drum mixer 15 at equal intervals (equal angles) in the circumferential direction, for example, four to twelve (eight in this case) according to the scale of the drum mixer 15. Moreover, they are provided linearly and continuously over the longitudinal direction of the drum mixer 15. The lifter may be provided in a spiral shape around the axis of the drum mixer, or may be provided intermittently over the longitudinal direction of the drum mixer.

As described above, when the lifter 17 is provided on the inner surface 16 of the drum mixer 15, it is necessary to ensure a sufficient height to forcibly scrape the sintering raw material 10. The sintered raw material 10 existing from the inner surface 16 of the drum mixer 15 to the upper end 19 of the lifter 17 is blocked by the lifter 17 and cannot roll. For this reason, since the sintering raw material 10 between the adjacent lifters 17 is unlikely to contribute to the granulation properties of the sintering raw material 10, the protrusion height (also referred to as lifter height) H of the lifter 17 is set. It is necessary to set the proper range.
Here, the result of investigating the change in the yield of the granulated product with the target particle size according to the protrusion height H of the lifter 17 and the laminated thickness h2 of the iron ore raw material will be described with reference to FIG. Here, a drum mixer having a diameter of 1.0 m is used as the drum mixer, the rotation speed is 20 rpm, the granulation treatment time is 2 minutes, and the iron ore raw material charging speed is variously changed, so that the iron ore is changed. The raw material laminate thickness h2 was changed to produce a granulated product having a water content of 9.5% by mass.

As shown in FIG. 8, the yield of the granulated product having the target particle size is increased by providing a lifter, and the protrusion height H of the lifter is increased when the protrusion height H is in the range of 10 mm to 30 mm. There is a tendency to decrease with it. From this, when the protrusion height H of the lifter exceeds 30 mm, the above-described scraping action becomes excessive and the yield of the granulated product is further reduced, and the stacking thickness h2 of the iron ore raw material is excessively large. As a result, it can be seen that the yield of the granulated product having the target particle size further decreases. In addition, when the protrusion height H of the lifter was 30 mm, the yield of the granulated product with the target particle size could be secured by 50% by mass or more until the laminated thickness h2 of the iron ore raw material was 300 mm.
From the above, when using the drum mixer 15 provided with the plurality of lifters 17 on the inner surface 16 and granulating the sintered raw material 10 to produce a granulated product, the protrusion height H of the lifter 17 is 30 mm or less. In the stationary state of the drum mixer 15, the lamination thickness h2 of the sintering raw material 10 accumulated on the bottom 18 in the drum mixer 15 is set to 300 mm or less.

In order to further improve the yield of the granulated product having a particle size of 3 mm or more and 10 mm or less finally obtained, the protrusion height H of the lifter is preferably 25 mm or less, more preferably 20 mm or less. On the other hand, even if there is no lifter, as described above, if the laminated thickness h2 of the sintering raw material is adjusted, a granulated product with a target particle size can be produced with high yield. In order to make the effect of the above remarkable, it is preferable to set the protrusion height H of the lifter to 5 mm or more, more preferably 10 mm or more.
In order to further improve the yield of the granulated product having the target particle size, it is preferable to set the lamination thickness h2 of the sintering raw material to 250 mm or less, and further to 230 mm or less. On the other hand, the lower limit value of the lamination thickness h2 of the sintering raw material is the bottom of the drum mixer as described above, and the sintering raw material existing from the inner surface of the drum mixer to the upper end of the lifter is blocked by the lifter. Since it cannot move, it was made higher than the protrusion height H of the lifter. In addition, in order to stably produce a granulated product having a target particle size and further improve the yield, the lamination thickness h2 of the sintering raw material is set to {(lifter protrusion height H) +20} mm or more, Is preferably 100 mm or more.

Thus, when the sintering raw material 10 mainly composed of fine powder is granulated by the drum mixer 12 (same for 15), the influence of moisture on the granulation property is very large. Therefore, under the conditions in the present embodiment, water was added to the sintering raw material 10 so that the water content of the granulated product was in the range of 8 mass% to 11 mass%.
Here, when the moisture content of the granulated product is less than 8% by mass, the granulation is insufficient due to insufficient moisture. On the other hand, when it exceeds 12% by mass, for example, the granulation becomes excessive and coarse particles increase. In addition, since the raw material may adhere to the inner surface of the drum mixer, it is difficult to maintain the granulation property.

Therefore, in order to improve the yield of the granulated product with further improved quality, the lower limit of the moisture content of the granulated product is preferably 8.5% by mass, more preferably 9% by mass, The value is preferably 10.5% by mass.
Based on the above results, granulation with a particle size distribution of 3 mm or more and 10 mm or less is performed by granulating the sintering raw material 10 using the drum mixer 12 for, for example, 1 minute or more (there is no particular upper limit, but about 5 minutes). The yield of the product can be 50% by mass or more. The produced granulated product is sieved with a sieve sorter as necessary, and further dried with a dryer (not shown) and supplied to a sintering machine.

Next, examples carried out for confirming the effects of the present invention will be described.
Here, using a laboratory drum mixer having a diameter of 1 m, (1) the relationship between the lamination thickness of the raw materials and the yield of the granulated product with a target particle size (3 mm or more and 10 mm or less) (target 50 mass% or more); 2) Based on the results of studying the relationship between the protrusion height of the lifter and the raw material stacking thickness and the yield of the granulated product of the target particle size, based on the results of this study, using the actual drum mixer, the above (1) The results of studying the relationship (2) will be described. The actual drum mixer has a diameter of, for example, not less than 2 m and not more than 4 m.
First, using a laboratory drum mixer with a diameter of 1 m, changing the raw material stacking speed by changing the feed rate of the raw material by changing the rotational speed to 20 rpm and the granulation treatment time to 2 minutes, the moisture content is The result of producing a 9.5 mass% granulated product will be described with reference to Table 1. As described above, since the sintering raw material is mainly composed of iron ore and the particle size distribution is the same as that of iron ore, the raw material is iron ore containing 60% by mass of particles having a particle size of 250 μm or less. The raw material was used.

As shown in Table 1, when using a drum mixer with a smooth inner surface that is not equipped with a lifter, the yield of the granulated product with the target particle size is compared in the range where the thickness of the iron ore raw material is 10 mm or more and 30 mm or less. It became high. However, when the lamination thickness was 100 mm or more, the iron ore raw material slipped on the inner surface of the drum mixer, resulting in poor granulation.
On the other hand, when a drum mixer equipped with a lifter on the inner surface is used, in the range where the height of the lifter is 5 mm or more and 30 mm or less, the laminated thickness of the iron ore raw material is made higher than the lifter height, so that the granulated product of the target particle size The target yield was 50% by mass or more, particularly in the range from 100 mm to 300 mm. However, when the lamination thickness of the iron ore raw material was increased to 400 mm, the rolling state of the iron ore raw material was deteriorated and the yield of the granulated product was reduced. Moreover, when the lifter height was increased to 30 mm, the scraping tendency of the iron ore raw material became prominent and the yield of the granulated product having the target particle size tended to decrease, but the target yield was 50% by mass or more. Was secured.

From the above, when using a drum mixer without a lifter, the lamination thickness of the iron ore raw material should be 30 mm or less, and when using a drum mixer with a lifter, the lifter height should be 30 mm or less, The knowledge which can make the yield of the granulated material of a target particle size 50 mass% or more was obtained by making thickness exceed lifter height, especially 100 mm or more and 300 mm or less.
Next, based on this knowledge, using an actual drum mixer with a diameter of 3 m, changing the rotational speed to 6.5 rpm and the granulation treatment time to 2 minutes, variously changing the input speed of the iron ore raw material, The results of producing a granulated product having a moisture content of 9.5% by mass by changing the thickness of the iron ore raw material will be described with reference to Table 2. Here, for comparison with the conventional method, a numerical value indicating the area ratio of the iron ore raw material in the cross-sectional area of the drum mixer, that is, a space factor is also shown.

As is apparent from Table 2, the same results as those of the experimental drum mixer described above were obtained for the actual drum mixer having a diameter of 3 m.
Moreover, in Table 2, when a drum mixer without a lifter is used, the yield of the granulated material having a target particle size is increased when the lamination thickness is 30 mm or less, but the space factor of the iron ore raw material is less than 1%, This was not preferable from the viewpoint of the productivity of the granulated product. However, by using a drum mixer with a lifter, the lamination thickness of the iron ore raw material is increased to 300 mm (particularly preferably 230 mm), that is, the space factor is increased to about 5% by mass (particularly preferably 3.5%). In addition, it was possible to secure a yield of 50% by mass of the granulated product having the target particle size, and to confirm that the productivity of the granulated product could be improved.

Here, the result in the case of using an iron ore raw material in which the amount of particles having a particle size of 250 μm or less is increased to 70% by mass will be described.
First, a drum mixer without a lifter was used, and the yields of the granulated products having the target particle sizes at a lamination thickness of 30 mm and 100 mm were compared. As shown in Table 2, when an iron ore raw material containing 60% by mass of fine particles is used, the yield of the granulated product having a target particle size is increased from 12% by mass to 59% by changing the lamination thickness from 100 mm to 30 mm. It increased about 5 times to mass%. On the other hand, when the iron ore raw material containing 70% by mass of fine powder particles was used, the yield of the granulated product having the target particle size increased 7 times or more from 9% by mass to 65% by mass.

Next, using a drum mixer equipped with a lifter having a height of 20 mm, the yields of the granulated products having a target particle size at a lamination thickness of 20 mm and 30 mm were compared. As shown in Table 2, when an iron ore raw material containing 60% by mass of fine particles is used, the yield of the granulated product having the target particle size is increased from 3% by mass to 29% by changing the lamination thickness from 20 mm to 30 mm. It increased about 10 times to mass%. On the other hand, when the iron ore raw material containing 70% by mass of fine particles was used, the yield of the granulated product having the target particle size increased from 3% by mass to 36% by mass by about 12 times.
From this, it was confirmed that the effect of the granulation method of the fine powder raw material of the present invention becomes more remarkable as the fine powder ratio increases.

Then, the result of having examined about the water content of the granulated material manufactured using the drum mixer for actual machines of diameter 3m is demonstrated, referring Table 3 and Table 4. FIG. Table 3 shows the results when the thickness of the iron ore raw material is set to 20 mm (space factor: 0.09%) using a drum mixer without a lifter, and Table 4 shows a lifter with a height of 10 mm. It is a result at the time of setting the lamination thickness of an iron ore raw material to 200 mm (space factor: 2.9%) using the provided drum mixer.

As is clear from Tables 3 and 4, when the moisture content of the granulated product is less than 8% by mass (7% by mass) regardless of the presence or absence of a lifter, the fine powder content due to insufficient granulation is due to insufficient moisture. There was a tendency that the yield of the granulated product with the target particle size decreased and decreased. On the other hand, when the water content of the granulated product exceeds 11% by mass (11.5% by mass), the adhesion between the iron ore raw materials becomes excessive, and the diameter of the granulated product becomes larger than the target particle size. There was a tendency for the yield of granulated particles to decrease.
From this, in order to further improve the yield of the granulated product having the target particle size, it is preferable to set the water content of the granulated product in the range of 8% by mass to 11% by mass.
From the above results, it was confirmed that by using the granulation method of the fine powder raw material of the present invention, a granulated product having a target particle size distribution can be produced with high yield from the sintered raw material mainly composed of fine powder. did it.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, the right scope of the present invention also includes a case where the granulation method for a fine powder material of the present invention is configured by combining some or all of the above-described embodiments and modifications.

10: Sintering raw material, 11: Inner surface, 12: Drum mixer, 13: Bottom, 15: Drum mixer, 16: Inner surface, 17: Lifter (slip suppression member), 18: Bottom, 19: Upper end

Claims (3)

A drum mixer that continuously granulates the sintered raw material by rolling and granulating the sintered raw material charged from one side and moving the produced granulated product to the other side and discharging it. A method for producing a granulated product by granulating a sintered raw material containing particles having a particle diameter of 250 μm or less in an amount of 60% by mass or more with the drum mixer having a smooth inner surface,
A granulation method of a fine powder raw material, wherein the lamination thickness of the sintered raw material accumulated at the bottom of the drum mixer is 30 mm or less when the drum mixer is stationary. A drum mixer that continuously granulates the sintered raw material by rolling and granulating the sintered raw material charged from one side and moving the produced granulated product to the other side and discharging it. And a plurality of slip suppression members that suppress the slip of the sintering raw material are provided so as to protrude from the inner surface of the drum mixer, and a sintering raw material containing 60% by mass or more of particles having a particle size of 250 μm or less is granulated by the drum mixer. A method for producing a granulated product,
The protrusion height of the slip suppression member from the inner surface of the drum mixer is set to 30 mm or less, and the lamination thickness of the sintered raw material accumulated at the bottom of the drum mixer in the stationary state of the drum mixer is set to the slip suppression. A method for granulating a raw material for fine powder, characterized in that the protruding height of the member is made to be 300 mm or less. The granulation method of the fine powder raw material according to any one of claims 1 and 2, wherein the water content of the granulated product is in the range of 8 mass% to 11 mass%. Granulation method.

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