JPS6013736B2 - Manufacturing method for spherical granules - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing spherical granules from powder.

More specifically, the summer sphericity is high, the grain viscosity is uniform,
Moreover, the present invention relates to a method for producing high-quality spherical granules with high mechanical strength on an industrial scale, efficiently, and economically. In general, granulation of powder into granules is known to have many advantages in the mining industry.

For example, the improved fluidity facilitates transportation, supply, packaging, etc. of solids, and also suppresses generation of dust and adhesion of powder to containers. Focusing on the advantages of these grains and spherical materials, recently the industrial and mining industries, especially steel, non-ferrous metals,
In technical fields such as cement, fertilizer, feed, pesticides, activated carbon, and carbon black, there is a great deal of interest in granulation technology for raw materials, intermediate products, or final products.
There are great expectations for the development of technology to produce high-quality spherical granules in large quantities at low cost. As a conventional method for producing grains or spherical granules from powder, rolling granules are employed in most cases. Transfer granules are made by sprinkling binder liquid while rolling powder raw materials in a granulator.
This is an operation to create aggregates or granules that are almost spherical and have the necessary strength. Specifically, the equipment used for this is a rotating plate type granulator or a rotating drum type granulator. This is a granulation device. According to this granulation method, relatively spherical granules can be produced in large quantities continuously, so it is widely used in various fields, but transfer granulation is a method of agglomeration granulation, Before the powder is supplied to the granulator, it is usually necessary to perform a so-called humidity conditioning pretreatment in which the powder is thoroughly mixed with a binder and water in a kneader. The necessity of this pre-flooding treatment process not only complicates the granulation process, but also inherently has the following drawbacks. In other words, the powder is covered with a liquid film during the pre-bran mixing in the humidity conditioning pre-treatment process, but ``if the mixing operation is insufficient, the liquid film may not be completely formed and may be incomplete. In this case, even if the granulation process is performed in an ideal manner, the binder added during granulation may not be present in the particles. It is not possible to spread or supply the binder evenly and evenly to the contact area.As a result, the dispersion of the binder becomes uneven, resulting in variations in the mechanical strength of the resulting granules, which may cause problems in subsequent processes such as drying. However, it is not possible to obtain sufficient mechanical strength as predicted from the amount of binder.Furthermore, since fast granules and slow granules are formed around the binder, agglomeration This causes the grains to slow down and the particle size distribution of the finished granules to widen greatly.These two problems, namely, difficulty in obtaining sufficient strength and broadening of the particle size distribution, As long as agglomeration granulation is carried out only by the rolling granulation method, it is considered to be a somewhat fateful process.On the other hand, the present inventors first developed a core, that is, a nucleus, in the rolling granulation machine. We tried coating and granulating by supplying raw material powder that had been subjected to humidity conditioning pretreatment, but due to the classification characteristics of the transfer granulator, coating and agglomeration granulation were not possible. At the same time, I learned that it was extremely difficult to scale granules with uniform particle size.

On the other hand, a new granulation method called centrifugal fluidized coating granulation has recently been developed.

This granulation method was invented from a completely different perspective from the conventional transfer granulation method, and its details are described in, for example, Japanese Patent Publication No. 46-22544. The outline is as follows. That is, the object to be coated is housed in a system consisting of a dish-shaped part that rotates approximately horizontally at the center, a deceleration part provided around the dish-shaped part, and a cylindrical part connected to the deceleration part. This is a method of coating and granulating granules by exposing the coating agent into the system while causing the object to be coated to flow through the system by rotating the part, and then ventilating the system from below or above as necessary. The spherical granules obtained by this method have extremely uniform particle sizes and high mechanical strength, and are therefore attracting attention as a new granulation method with extremely high industrial applicability.
However, it is said that it is difficult to make this method continuous in consideration of economic efficiency, and furthermore, it is not easy to increase the size of the device due to the design. Therefore, added value is low;
Moreover, it is not necessarily suitable for granulating products that require mass production. In view of the above circumstances,
The present inventors have conducted intensive research on a method for producing high-quality spherical granules from powder on a large scale, efficiently, and economically.As a result, we first determined that a specific A primary granulated material having a certain particle size is made, and then only coating granulation is performed while taking advantage of the classification characteristics of a rolling granulator. Compared to known methods, the granules are more uniformly arranged, and it is easy to machine. We have completed a method for efficiently producing spherical granules with high mechanical strength on an industrial scale.

That is, the present invention accommodates the core in a system consisting of a dish-shaped part that rotates approximately horizontally at the center, a deceleration part provided around the dish-shaped part, and a cylindrical part connected to the deceleration part. Dry powder and binder are fed into the system while the core is centrifugally fluidized by rotation of the shaped part to produce a primary granule, and the primary granule obtained here is transferred to a rolling granulator. Production of spherical granules, characterized in that granulation is carried out while supplying dry powder and a binder to produce spherical granules whose average particle diameter is up to four times the average particle diameter of the primary granules. It is the law. In other words, the method of the present invention first uses a centrifugal fluid coating device to coat particles with uniform particle size and high mechanical strength.
A secondary granulate is made, with the average particle diameter of the primary granulate being at least 1/4 of the average particle diameter of the final granulate, and this is fed to a transfer granulator. This is a method in which granulation is continued by supplying the dry powder and a binder to form spherical granules with an average particle size of up to four times the average particle size of the primary granules. According to the method of the present invention, almost no agglomeration granulation is performed in the tumbling granulator, and only coating granulation is performed. A new method for granulating spherical granules is provided that takes full advantage of the above methods and overcomes the drawbacks of both devices. Next, the granulation method of the present invention will be specifically explained.

First, as a centrifugal fluid coating apparatus for producing the primary granules, for example, apparatuses such as those shown in FIGS. 1 to 6 are used. In the device shown in the drawing, a granulation section A is constituted by a rotating plate-shaped section 1, a deceleration section 5 for smoothing the direction of movement of the granulated material, and a cylindrical section 3 connected to this deceleration section. . The rotating plate-like portion 1 is fixed to a substantially vertical rotating shaft 7. , the rotational speed of the rotating plate-shaped portion can be changed freely. This dish-shaped part 1 may be flat, or may be a dish with a raised peripheral area, or may have a conical protrusion 2 at the center of the dish-shaped part. . The rotational speed of the dish-shaped part can be determined appropriately depending on the size of the device, the type of raw material, the particle size of the core and the raw material powder to be spread, etc., but in general, the peripheral speed should be 10 m/sec or less. The speed is preferably 2 to 7 m/sec. The raw material powder supply port 4 may be provided with a binder spray nozzle 14 in the upper part of the granulation part A, and the upper part of the cylindrical part 3 is closed with a lid 12 as shown in FIG. A supply port 4 may also be provided. Furthermore, as shown in FIGS. 3 and 4, for example, a non-slip member 13 may be provided on the upper surface of the rotary plate-shaped portion 1 in order to make the movement of the particles smoother. Further, as shown in FIG. 5, a hollow part 11 is provided in the bottom plate of the conical protrusion 2, and a ventilation hole 9 is provided around the circumference, and the rotating shaft 7 is made hollow so that gas such as air can be blown into it from the inlet 6. Good too. Alternatively, the air inlet 6 may be provided at the top of the device as shown in FIGS. 2 and 3, or a space B may be provided at the bottom of the device as shown in FIG. It is also possible to supply gas and vent the gas into the device through the gap 10 between the rotary plate and the speed reducer. 1st
In the figure, the rotating shaft 7 is located at the bottom of the apparatus via the sealing 8, but it may be provided from above so as to pass through the granulation section A.
Generally, it is desirable that the speed reducer 5 has a curved cross section as shown in the drawings, but it can also have a straight cross section as shown in FIG. 6 if desired. Further, the deceleration part 5 is joined to the cylindrical part 3 or is configured integrally with the cylindrical part 3, and is fixed so as to have an appropriate gap 10 from the periphery of the rotating plate-shaped part 1. When the deceleration part 5 has a curved cross section, the cross section from the rotary plate-shaped part 1 to the cylindrical part 3 is a continuous smooth curve, and granulation is performed very effectively. The cylindrical part 3 may have a shape in which the opening part thereof is open in a morning glory shape, or may have a shape in which it is somewhat easy to squeeze. In addition,
This granulation device may be equipped with a binder atomizing nozzle, a dusting device, a moisture detector, etc., and connected to an automatic control device to automatically carry out the granulation operation. In order to carry out coating granulation using such a far-flow coating bag layer, for example, there is a method of granulating the core while displacing the coating solution containing a binder, and a raw material whose core has been pretreated with moisture conditioning. Although methods such as spreading wet powder and granulating it are already known,
In producing the primary granulated product in the method of the present invention, a method is used in which the dry raw powder and the binder are supplied to the core from separate supply ports for granulation. It is preferable that the particles to be used as the core, that is, the nucleus used here, have a uniformity coefficient as small as possible for the particle group, but it may be obtained by any means.

For example, it may be obtained by charging a dry powder into a centrifugal fluid coating device and centrifugally fluidizing it while exposing an appropriate binder, or by crushing the material to be made into a core by an appropriate means and separating it into grains. It may be something you have obtained. Among these methods, when granulation is performed from dry powder using a centrifugal fluid coating device, core formation and subsequent formation of primary granules by the method of the present invention are performed in the same device. Not only can it be carried out continuously, but it is also advantageous in many cases because cores of uniform particle size can be obtained without complicated operations such as classification into separate pieces. Further, the core may be different from the raw material powder to be granulated, or may be the same. In most cases, it is desirable that the core has a particle size larger than about 40 mm, and it is desirable that the uniformity coefficient of the particle group be as small as possible. ＼On the other hand, good results are often obtained when using raw material powder with a particle size smaller than about 25%, and usually it is used as a dry powder with a moisture content of about 3% by weight or less. Good.

The raw material powder in the method of the present invention may be any powder that can be used as a raw material for spherical granules in the field of engineering and mining technology, such as activated carbon raw material powder,
Examples include metal ore powder, cement raw material powder, powder for fertilizers, pesticides, feed, etc. In addition, the binder used in the method of the present invention may be water or the organic solvent itself, or a powder that is insoluble in water but disperses well in water, such as clay, bentonite, slaked lime, gypsum, and cement.
Water-repellent substances such as alkali metal hydroxides, water glass, pulp waste liquid, starch, bran, cellulose ethers,
Dissolve or disperse gum arabic, dextrin, polywax, salt, synthetic resin, etc., or non-water lagoonal substances that are soluble in organic solvents, such as bitumen, tar, paraffin, wax, pitch, asphalt, etc. in an appropriate solvent. Any binder that can be used as a binder in conventional granulation methods, such as binders, can be conveniently used.

In the method of the present invention, first, a primary granule is produced using a centrifugal fluid coating device.

That is, the core is housed in a far-0 flow coating device, and the raw material powder and binder are supplied into the system from separate supply ports while rotating the rotating dish-shaped part to perform coating granulation, thereby performing primary granulation. You can get things. When producing primary granules using a far-zero flow coating device of the type shown in FIG. Due to the rotation of the protrusion 2, the granules move circularly around the rotating shaft 7 and are pushed up from the center to the periphery along the rotating dish-shaped part 1 by centrifugal force, and as a result, the upper layer of the center part is pushed up by the centrifugal force. The granules descend along the conical projections 2. Moreover, the granulated material pushed up to the peripheral part is further pushed up along the deceleration part 5 and the cylindrical part 3, reaches the uppermost layer part, and collapses toward the center. The repetition of such movements results in a spiral circular movement.
By making the granules flow by using centrifugal force, gravity, and frictional force, that is, by centrifugal flow, the abrasiveness of the particles and the spreadability of the binder are improved. Therefore, when granulating using a centrifugal fluid coating device, this device itself has a kneading function, and as a result, a separate moat and kneading function as in the conventionally used coating and granulating device is required. Not only does it eliminate the need for equipment, but
The primary granules obtained are spherical granules with uniform particle size and high strength. The above is the details of the process of manufacturing the primary granules, but as mentioned earlier, as the core,
It is convenient to use pongee grains obtained by centrifugal flow using a centrifugal flow coating device, feeding dry powder and binder.

That is, in the above-mentioned method, drying is carried out as a core into a system consisting of a dish-shaped part in the center that rotates approximately flat, a deceleration part provided around the dish, and a cylindrical part connected to the deceleration part. This method uses spherical particles obtained by supplying powder and a binder and rotating a dish-shaped part to cause centrifugal flow. When manufacturing the core by this means, the core
The production of the primary granules and the production of the primary granules can be carried out successively in the same apparatus. For example, using the far-zero flow coating device shown in FIG. While rotating the unit, the binder liquid is applied from the mist nozzle 14 onto the raw material powder. When a certain amount of binder is supplied to the raw material powder, the raw material powder is agglomerated and becomes granular to form a core for primary granulation. Continuously, or if desired, the core is transferred to another far-D fluid coating device, and the binder and raw material dry powder are fed continuously or intermittently from separate supply ports, and the core is enlarged while being coated with the raw material powder. By doing so, primary granules are obtained. In this case, by automatically detecting the water content of the mixture in the far-D fluidized coating apparatus, it is also possible to automatically control the combined amount of the binder and raw material powder. In the method of the present invention, the primary granules thus obtained are supplied to a rolling granulator, and the raw material powder is appropriately supplied with a binder and subjected to rolling granulation. and subjected to a step of forming spherical granules.

As the transfer granulator used here, any of the three commonly used transfer granulators, such as a dish-type granulator or a drum-type granulator, can be conveniently used. In addition, the raw material powder, binder, etc. used at this time may be the same as those used in the production of the primary granules, or may be changed as needed or depending on the purpose to use a different type of material. may also be used. Transfer granulation in the method of the present invention is carried out by means known per se using the above-mentioned equipment and materials, and the primary granules are grown to a size up to about four times the average diameter. It will be done.

That is, dry powder and binder are continuously or intermittent fed to the primary granules fed to the rolling granulator from separate feed ports in appropriate proportions to perform dry coating granulation. The desired spherical granules are continuously taken out. When obtaining spherical granules by transfer granulation, we investigated the mechanical strength and particle size distribution of the spherical granules, which are the product, and found that the physical properties, the average particle diameter of the primary granules, and the spherical product It was found that there is a close relationship between the ratio and the average particle diameter of the granulated product.

In other words, in order to increase the mechanical strength of the spherical granules that are the product and to make the particle size uniform, as is clear from the experimental examples shown below, the average particle size of the primary granules must be It is desirable that the average grain size of the granules is 1/4 or more. Raw materials used in the experiment: Equipment using iron and steel stone powder Centrifugal flow coating equipment (rotating plate diameter 360 mm, depth 2
75 ribs (of the type shown in Figure 1) dish type granulator (dish diameter 5
00 side, depth 15 yards, angle 500) Iron ore powder (100 mesh 100%) Raw material for manufacturing primary granules 200
Mesh 80% strained product Moisture 1. Bamboo weight%) 2.0k9
is charged into a centrifugal fluid coating device, and the rotating plate-shaped part is rotated at a circumferential speed of 3 skins/
1 sodium silicate as a binder while rotating in seconds.
When a 6% by weight aqueous solution was supplied while being sprayed at a rate of 6'/min, primary granules with a particle size of 1.0±0.5 ribs were obtained after 30 minutes.

When granules were produced by the same operation as above, coating and granulation was continued while feeding the raw iron ore powder at a rate of 0.5 kg/min and the binder at a rate of 40 kg/min, until the particle size was 2.0±. 0.5
A primary granulated product of legs was obtained.

In the same manner, primary granules with particle sizes of 3.0 ± 0.5 ribs, 4.5 ± 0.5 ribs, 8.0 ± 0.5 ribs, and 12.0 soil 0.5 legs were prepared. . Production of spherical granules The dish-type granulator was rotated in advance at 35 rpm, and the primary granules and dry raw material powder were rotated at 0.07 k9/min and 0.5 k9/min, respectively.
Granulation was carried out by supplying at a rate of 3k9/min and at the same time atomizing the same binder as in the previous step at a rate of 48M/min, resulting in an average particle size of 16.5 m/min from each of the primary granules. ．．
Granulation was carried out until a second spherical granule was obtained.

Particle size distribution of the product The relationship between the particle size and weight distribution of the spherical granules obtained from each primary particle is as shown in FIG.

Symbols ■, ■, ■, ■, ■, ■ in the figure indicate the particle size of the primary granules, 1. Enemy, 2.0 ribs, 3. W snout, 4.5 skin, 8
．． 12. The dashed line shows the particle size distribution of the primary granulated product, and the solid line shows the particle size distribution of the spherical granulated product. The value obtained by dividing the particle size by the particle size for which the cumulative under-sieve weight is 1% by weight, hereinafter calculated as 6% by weight particle size/1
Displayed as 0% particle size by weight.

) were as shown in Table 1. Table 1 In the method of the present invention, the production of primary granules is carried out using a centrifugal flow coating device, but when this is carried out using a rolling granulator, the agglomeration granulation described earlier Because of the fateful problem of
Since the particle size of the primary granules themselves is not uniform, it is essential to insert a dividing step after the primary granulation.

Furthermore, since the mechanical strength of the primary granules is poor, the granules may be broken or powdered in the granulation equipment during the covering granulation process using the subsequent granulation equipment. This will cause inconvenience. The features of the method of the present invention can be easily understood from the above detailed description, and these can be summarized in the following points.

{1} The method of the present invention eliminates the need for kneading equipment as in the conventional method, and allows the dry powder to be directly supplied to the granulation device.

■ Since a centrifugal flow coating device is used to produce the primary granules, circulating motion on the spiral is forced, and the solid particles are subject to a kind of crosstalk in the granulation device, while at the same time the spreadability of the binder is also affected. Since the dry powder coating and granulation are carried out, primary granules with high mechanical strength can be obtained.

In addition, since coated granulation is performed, the particle size of the primary granules is also made uniform. Since the '3' primary granules are continuously subjected to dry powder coating granulation using a transfer granulator, it is possible to continuously obtain spherical granules with uniform particle size and high mechanical strength.

Moreover, by controlling the supply ratio of the primary granules and the raw material powder within a certain range, it is possible to produce spherical granules having a desired particle size and high sphericity. The method of the present invention will be described in detail below with reference to Examples.

Example 1 Granulation of coal powder for spherical activated carbon The equipment used in this example is the centrifugal fluid coating equipment and dish-type granulator used in the experimental examples.

First, coal powder for spherical activated carbon (20
0 mesh wired product 80%, moisture 1. % by weight), and while rotating the rotating dish-shaped part at a circumferential speed of 4.5 m/sec, a sulfite pulp waste liquid (solid content concentration 35% by weight) was sprayed as a binder at a speed of 5.5 m/min. If supplied from 30
660 cores with an average grain size of 48 mm are obtained in 1 minute.

Subsequently, the same dry powder and binder as above were added at two doses each while rotating the rotating plate at a circumferential speed of 4.5 skins/second.
When coating granulation is carried out while feeding at a rate of 2.2 min/min and 4.6 min/min, primary granules of about 3k9 with an average particle size of 71 m are obtained in 9 min. The obtained primary granules and the same dry raw material powder as above were mixed at a ratio of 1:12 and transferred to a dish-type granulator rotating at 2 rotations/min at a speed of 30 rotations/min. The same binder as above was continued to be fed while being jetted at a rate of 5.8 m/min, and the spherical granules overflowing from the dish-type granulator were collected.

On the other hand, for comparison, raw material dry powder and binder were kneaded in advance at a ratio of 100:15 using a grinder, and then fed to the same dish-type granulator as above at a rate of 120 min/min for agglomeration. Stream formation is performed, and the granules that overflow from the flow formation device are collected. Table 2 shows a comparison of the physical properties of the spherical granules obtained by the method of the present invention and the granules obtained only by a dish-type granulator.

As is clear from Table 2, the spherical granules obtained by the method of the present invention have a narrower particle distribution, compared to granules obtained only by a dish granulator. uniformly aligned,
It can be seen that other physical properties are also excellent. Table 2 (Note 1) 10 weight particle size (Note 2) 60 weight% particle size/10 weight *Particle size (Note 3) Average particle size.

(Note 4) Average value obtained by measuring 50 grains using Shimadzu Autograph (dry grains are used) (Note 5) According to Japanese Industrial Standard (JIS) 1474.

(Note 6) 15 samples were taken, and the 10 pieces were tied with 1000 JIS standard knots, and the 10 pieces were housed in a stainless steel cylinder with an inner diameter of 25 willow and a length of 305 mm containing a 5/16 inch diameter steel ball. After applying impact by rotating at 25 rpm for 10 minutes, the sample was subjected to 1000 JIS knots, and the value obtained by dividing the cut product by the charged amount is expressed as a percentage. Example 2 Granulation of Iron Ore Powder The equipment used in this example is the far-D fluidized coating equipment and dish-type granulator used in the experimental examples.

Raw iron ore powder (100 mesh reduced product, 200 mesh reinforced product 80%, water content 1.8% by weight) 2.0k9 was charged into a far-D fluidized coating device, and the rotating plate was rotated at a peripheral speed of 3/sec. While rotating at a speed of 1.5% by weight, a 1% by weight aqueous solution of sodium silicate as a binder is supplied at a rate of 6°/min. After 30 minutes, the average particle size becomes 1.5% by weight. Obtains the core of the enemy.

When the core is formed, add 0.5% of the same dry iron ore powder as above.
If coating granulation is continued by supplying the binder at a rate of 40 kg/min and a binder at a rate of 40 kg/min, granules with an average particle size of 2 Yanagi will be obtained after about 30 minutes. This granulated product 2k9 is charged into the same centrifugal fluid coating equipment,
When granulated using the same procedure as above, the average particle size is 8 with approximately 3 powders.
．． A 6-ton primary granule is obtained. Next, the primary granulated material and the dry raw material powder were placed in a dish-type granulator rotating at 35 revolutions/min at 0.07 k9/min and 0.53 k9/min, respectively.
The same binder as above is simultaneously fed with a spraying rate of 48'/min.

The spherical granules that overflow from the dish granulator at a constant rate are collected as a product. On the other hand, for comparison, 6.5% by weight of water was added in advance to the same iron ore powder as above and thoroughly kneaded with a kneader to prepare a wet raw material powder, which was the same as that used in this example. 33 kg/min of sodium silicate as a binder.
．． Marugame % aqueous solution is atomized at a rate of 9.6 Z/min to perform coagulation and granulation, and the granules overflowing at a constant rate are collected. Table 3 shows a comparison of the physical properties of the spherical granules obtained by the method of the present invention and the granules obtained only by a dish-type granulator.

As is clear from Table 3, the spherical granules obtained by the method of the present invention are significantly superior in terms of grain distribution and mechanical strength compared to granules obtained only by a dish-type granulator. It turns out that it is excellent. Table 3 (Note) Measurement methods for physical properties are the same as in Table 2.

Example 3 Granulation of coal powder for spherical activated carbon The equipment used in this example was the centrifugal fluid coating equipment and dish-type granulator used in the reference example.

Crushed raw coal with an average particle size of 52 and a uniformity coefficient of 1.6 50
0 water was charged into a centrifugal fluid coating device, and the rotating plate-shaped part was set at a circumferential speed of 4.
．． At the same time, a sulfite pulp waste liquid (35 wt. When coated granulation is performed by supplying .0 wt.
A primary granulated product with a particle size of 0 is obtained.

The uniformity factor of this product is 1.4. * The primary granules and dry coal powder were mixed at a ratio of 1:8 and fed at a speed of 30 rpm to a dish-type granulator that had been rotated at 29 rpm in advance, and then mixed in the same manner as above. of sulfite pulp waste liquid for 5.6 days/day
The spherical granules flowing out are collected as a product.

The average particle size of this product is on the 16 side. On the other hand, for comparison, dry coal powder and sulfite pulp waste liquid were mixed in a kneader at 100%
:15 and fed to a dish granulator at a rate of 120 m/min for agglomeration and granulation, and the overflowing granules were collected. The physical properties and particle size distribution of the spherical granules obtained by the method of the present invention and the granules produced only using a dish-type granulator are shown in Table 4. Table 4 (Note) Measurement methods for physical properties, etc. are the same as in Table 2.

Example 4 Granulation of iron ore powder The equipment used in this example is the centrifugal fluid coating equipment and dish-type granulator used in the reference example.

However, the angle of inclination of the dish-type granulator is 47°. Crushed iron ore 2 with average particle size 2.09 willow and uniformity coefficient 1.53
．． 0k9 was placed in a centrifugal fluid coating device, and since the rotating plate-like part could not be rotated at a circumferential speed of 3 m/sec, a 1% by weight aqueous solution of sodium silicate was supplied as a binder at a rate of 24'/min, and the other side was dried. Iron ore powder (100 mesh waste product, 20
0.3 mesh (80% strained product, moisture 1.5% or less)
When coated granulation is performed by feeding at a rate of k9/min, approximately 47
Average grains per minute 8. As a result, primary granules with a uniformity coefficient of 1.07 are obtained. The primary granules and dry iron ore powder were fed at a rate of 0.07 k9/min and 0.53 k9/min, respectively, into a dish-type granulator which had been rotated at 35 revolutions/min, and at the same time silica was added as a binder. sodium acid 1% by weight
Granulation is carried out by supplying the aqueous solution at a rate of 48 K'/min,
The spherical granules that overflow from the dish granulator at a constant speed are collected as a product.

On the other hand, for comparison, 6.5% was added to the same iron ore powder as above.
A wet raw material powder is prepared by adding % by weight of water and thoroughly kneading it in a kneader, and then transfer it to the same dish-type granulator as above for 0.3k.
At the same time, a 33.3% by weight aqueous solution of sodium silicate was fed as a binder at a rate of 9.9% by weight. The fins are atomized at a speed of about 100 m/min to perform agglomeration and granulation, and the granulated material overflowing at a constant speed is collected.

Table 5 shows a comparison of the physical properties, grain distribution, etc. of the granulated product obtained by the method of the present invention and the granulated product obtained only by a dish-type granulator. Table 5 Brief Description of the Drawings Figures 1, 2, 3, 5, and 6 show planes passing through the center line of several examples of centrifugal flow coating devices used in the method of the present invention. FIG. 4 is a plan view of the rotary plate-shaped portion of the device shown in FIG. 3, and FIG. 7 is a diagram showing the results of a reference example.

Multi-box 2 diagram Many 3 figures Multi 4 figures Multi-5 diagrams Multi 6 diagrams Figure 7

Claims (1)

[Scope of Claims] 1. A core is housed in a system consisting of a dish-shaped part that rotates approximately horizontally at the center, a reduction part provided around the dish part, and a cylindrical part connected to the reduction part, Dry powder and binder are fed into the system while the core is centrifugally flowed by rotation of the dish-shaped part to produce a primary granule, and the primary granule obtained here is transferred to a rolling granulator. A spherical granule, characterized in that granulation is carried out while supplying a dry powder and a binder to obtain a spherical granule having an average particle diameter of up to four times the average particle diameter of the primary granule. Manufacturing method. 2. The dry powder and binder are supplied into a system that serves as a core and consists of a dish-shaped part that rotates almost horizontally at the center, a deceleration part provided around the dish-shaped part, and a cylindrical part connected to the deceleration part. 2. The method according to claim 1, which uses spherical particles obtained by rotating a dish-shaped part to cause centrifugal flow.