JPH0639265A - Method for mixing and granulating powders - Google Patents

Abstract

PURPOSE:To mix and granulate powders with a compact device by providing a high-speed rotary agitator at an eccentric position in a closed vertical rotating vessel, circulating raw powders between the accumulation position at the lower part in the vessel and the suspension and dispersion position at the upper part in the vessel and spraying a liq. binder on the powders. CONSTITUTION:A closed vertical rotating vessel 1 rotating around the center axis and a high-speed rotary agitator 14 set at the eccentric position of the vessel 1 and made free from the rotation of the vessel 1 are used, raw powders are circulated between the accumulation position at the lower part in the vessel 1 and the suspension and dispersion position at the upper part in the vessel 1, and a liq. binder is atomized and supplied, as required, into the circulating system from a spraying device 15. As a result, the powders are mixed and/or granulated at a low cost with this compact device, and a high-quality product is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder mixing method and a granulating method applicable to various industrial fields such as the ceramic industry, food industry and chemical industry.

[0002]

2. Description of the Related Art Uniform mixing of powders is difficult except for special cases, and the process is complicated and costly. This is because the powder has a larger surface area than the volume and particles adjacent to each other tend to agglomerate to prevent uniform mixing. By the way, the degree of agglomeration depends on the raw material composition and ratio of the powder, the particle size, the morphology of the crushed particles, the degree of coarse crushing and the particle size distribution, and the manufacturing method of the powder (for example, mechanical crushing is abrasion crushing). And impact pulverization is different in the degree of disorder of the structure of the particle surface) and so on.

In the case of uniformly mixing and granulating the powder on an industrial scale, it is necessary to take measures to prevent the powder from agglomerating. The typical examples that are currently being practiced are as follows. It is as 3).

(1) Powder, additives, hard balls, etc. are put in a container and the container is rotated to mix. Alternatively, a method of mixing by rotating a stirring blade in a fixed container.

(2) A method in which powder and gas are simultaneously supplied into a container, and once dispersed in an air stream to weaken the cohesive force and then dispersed and mixed and granulated in the air stream.

(3) A method in which the powder is made into a slurry in water to weaken the cohesive force between the particles, and the water and the particles are integrated and mixed and granulated.

As a mixing method of (1), the production of cement, which is said to be a drum type or a ball mill type, can be fried as a typical example. In this method, the powder is mechanically forcibly mixed in the agglomerated state, so put the powder and water or solvent for dry mixing for several hours, then add the additives and perform wet mixing for several hours. However, there is a problem that it takes time, and the production cost becomes high.

As specific examples of the mixed granulation method (2), the following (a) to (e) can be fried.

(A) Japanese Patent Laid-Open No. 55-88834 A powder and an air stream are simultaneously charged from a lower charging port, and a spiral blade in a container is rotated by the air stream so that the powder collides with the blade. A method in which the powder and the air stream are discharged simultaneously from the discharge port on the top by mixing.

(B) JP-A-60-161721 / 1
No. 61722 The powder and the air flow are supplied to the container from the inlet having the spiral air flow generation device, and are dispersed and mixed by passing the rotating air flow depending on the shape of the cyclone container or the air pressure adjusting device from the lower part, and the gas in the upper part. A method of discharging the powder from the discharge port and collecting the powder from the lower part.

(C) Japanese Patent Application Laid-Open No. 1-159039 A gas is supplied from the lower part to float and mix the powder, and the powder is collected by a bag filter of a dust collector connected to a discharge port on the upper part. The gas flow is discharged by a fan.

(D) Japanese Unexamined Patent Publication No. 2-157033 A powder is dispersed and mixed by a stirring blade that is rotated around a central axis of a vertical cylindrical shape, a stirring blade at the bottom of the bottom and pressure air from the bottom. A method of simultaneously discharging powder and air flow from the upper part.

(E) Japanese Unexamined Patent Publication (Kokai) No. 2-251254 By a stirring blade which is rotated around a central axis of a vertical cylindrical shape, a stirring ball which is rotatably flown by a stirring blade at the bottom of the bottom, and pressure air from the bottom. , A method in which the powder is dispersed and mixed, and the powder and the air stream are simultaneously discharged from the upper part.

What is common to (a) to (e) is that the powder is forcibly dispersed by externally supplying an air flow into the container in order to weaken the cohesive force of the powder. After the completion of the mixing work, an enormous amount of powder and gas must be conveyed to the next step to separate the powder from the gas, which causes the following problems.

A. A device for supplying air, gas, etc. is required, and the equipment is complicated and expensive.

B. Powder and gas separation devices such as bag filters, cyclones, and various air cleaning devices are required, which makes equipment complicated and expensive, and also requires a large installation area.

C. Since the powder is discharged together with the gasified gas, the powder having a low specific gravity affects the morphology and distribution of the particles, and uniform mixing is difficult.

D. Since the mixing is performed by the air flow in the container, even if the mixing is insufficient, the powder is continuously discharged to the next step together with the air flow, and the mixing is insufficient.

E. Since the time required until the powder is supplied into the container and discharged is the mixing time (passing method), it is difficult to uniformly mix the powder. That is, it is necessary to enlarge the equipment such as the container and prolong the mixing time. (It is necessary to lengthen the time for the powder to pass through the container.) Regarding the method of dispersing and mixing the powder in water in (3), it is mainly used for mass production such as tile manufacturing. Examples of the method include a method in which a filter is pressed, dried, pulverized into pellets and used through a sieving machine, and a spray dryer method.

In this case, for example, when the spray dryer method is applied, the raw material powder is uniformly dispersed in the aqueous solution, so that granulation can be carried out under a uniform mixed state. That is, in the spray dryer method, a raw material powder and a water-soluble binder are uniformly mixed in a solution to form a slurry, which is sprayed and atomized from the upper part and dropped, and supplied from the lower part and side parts during this drop. This is a method of drying and granulating by using hot air. According to this method, it is possible to obtain a homogeneous aggregate having a spherical shape and good fluidity. However, this method has the following problems.

A. Since it is a method of drying instantly, hollow granulated particles are likely to be formed, and the granulated particles are easily crushed during movement.
Further, it is difficult to obtain a product having a high bulk specific gravity.

B. A large amount of heat energy is required to evaporate the water content from the state of the slurry, but the processing capacity is low, but the cost is high.

C. Since a large processing space is required for spraying, drying and granulating the slurry, the apparatus becomes large and requires a large installation space, resulting in high equipment costs.

Regarding granulation, in general, for the purpose of improving the handling property of fine powder having poor fluidity, a substance having low adhesiveness is granulated and the surface of the powder is modified to improve fluidity. Improvements and methods of depositing a solution on a plurality of mixed powders.

An example of the granulation method is as follows.

(A) Japanese Patent Laid-Open No. 62-65729 When a porous plate at the bottom of a cylinder is rotated, powder suspended by compressed air is solvent sprayed from the upper part into a small hole of the porous plate and pressed. How to granulate.

(B) Japanese Patent Application Laid-Open No. 1-135524 A method in which a rotating container is sprayed with a solvent from a plurality of nozzles for mixing and granulation.

However, these granulating methods also have the following problems.

In the case of (a) a. Since granules are pressed and granulated, it is difficult to obtain spherical aggregates with good fluidity.

Further, the small holes of the perforated plate are likely to be clogged.

B. Ancillary equipment such as an air filter and exhaust device is required, and the equipment becomes large.

On the other hand, since the processing capacity is low, the cost is high.

C. When the powder is circulated, a rotating porous plate, a stirring bar, compressed hot air or the like makes it difficult for the powder to be dispersed and moved freely as the powder becomes aggregated, resulting in an insufficient granulated product.

In the case of (b) a. Due to the structure, pipes with nozzles are put into and taken out of the container each time, so workability is poor and mass production is not possible.

B. The mixing time and granulation time require a long time of 1 hour or more, resulting in high cost.

The present invention has been made for the purpose of eliminating such conventional problems.

[0037]

DISCLOSURE OF THE INVENTION The present invention relates to a closed vertical rotary container which rotates about a central axis, and an agitator which is installed at an eccentric position in the rotary container so as to be free from rotation of the container. A method of mixing powders using an apparatus, in which the raw material powder deposited in the lower part of the rotary container is moved in the same rotational direction as the container is rotated in the same rotational direction while passing the eccentric installation position of the stirring device. And a step of blowing up the raw material powder by high-speed rotation of the stirring device to float and disperse in the upper space of the rotating container when passing through the above position, and after the floating and dispersion, depositing on the lower part of the container by self-weight sedimentation. And a method of mixing powder, characterized in that the raw material powder is circulated between the deposition position at the bottom of the container and the floating dispersion position at the top of the container by repeating the above steps, and with the central axis as the center of rotation. Rotating closed vertical A method for granulating powder by using a rotary container and an agitator installed at an eccentric position in the rotary container so as to be free from rotation of the container, wherein the powder is deposited on the lower part of the rotary container. A step of passing the raw material powder through an eccentric installation position of the stirring device while moving the same in the rotational direction as the container rotates, and at the time of passing through the position, blow the raw material powder by high-speed rotation of the stirring device. A process of suspending and dispersing in the upper space of the rotating container, agglomerating the floating dispersed powder by collision with binder droplets spray-supplied in the upper space of the container, and depositing it in the lower part of the container by gravity settling The present invention relates to a method for granulating powder, characterized in that the raw material powder is circulated between a deposition position at the bottom of the container and a floating dispersion position at the top of the container by repeating the above steps.

[0038]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show an example of an apparatus suitable for carrying out the mixing method and the granulation method according to the present invention. This apparatus is a vertical rotary container which rotates about a central axis. (1) is provided.

The rotary container (1) has a cylindrical shape with a lid and a bottom, and a settling and accumulating space (3) for the raw material powder (2) at the bottom.
Has a floating dispersion space (4) for the same powder in the upper part, and a take-out port (5) for the raw material powder after mixing or granulation in the center of the bottom part, and opening / closing or detaching for closing the take-out port (5) A free lid member (6) is provided. Rotating container (1)
The upper end opening (7) is closed by a fixing member (8) supported and fixed to a fixing member in the vicinity thereof, for example, a frame (not shown) of the device, an indoor wall, a pillar, or the like. ), The raw material powder charging port (9) and the charging port (9)
And a lid member (10) that can be opened and closed or is detachable.

An inwardly projecting flange portion (1a) is formed at the upper end of the container (1) for the purpose of enlarging the area of the seal between the upper end of the rotating container (1) and the fixed lid (8). be able to.

The rotating container (1) is provided with a drive device (11) for giving rotation to the container (1). As a drive device (11), a large-diameter gear (11a) fitted and fixed to a body of a rotary container (1) and a small-diameter gear (11b) driven by a motor (11c) that meshes with the gear (11a) are shown in the figure. ) And is shown, but other configurations may be used.

The rotary container (1) is installed, for example, on a stand (13) having legs (12) and having a central opening, so that it can rotate at a fixed position.

The stirring device (14) is installed at an eccentric position in the rotary container (1) so as to be free from rotation of the container (1). The stirring device (14) includes a rotating shaft (14a), a blade member (14b) mounted and fixed to the rotating shaft (14a) in a multi-step manner, and a drive device (14c) for giving high speed rotation to the rotating shaft (14a). ) And is composed of. Rotation axis (1
4a) is rotatably inserted through and supported by a fixed lid (8) via a bearing (not shown), and the lower end extends to near the bottom of the rotary container (1).

The central axis of the rotary shaft (14a) and the central axis of the rotary container (1) are parallel to each other. Rotating shaft (14
The insertion position of (a) is appropriate at or near the midpoint of the radius of the rotary container (1), and the length of the blade member (14b) projecting radially from the shaft (14a) is as described above. About 1/2 of the radius is suitable.

The shape of the blade member (14b) is such that the raw material powder settled and deposited in the lower space (3) of the rotary container (1) can be blown up toward the upper space (4) by high-speed rotation to be suspended and dispersed. Any shape may be used, and for example, parallel blades as illustrated are used. Blade member (14
The number of steps and the vertical interval in b) may be appropriately selected and determined.
Blade member (14b) located in the lower space (3)
Mainly serves to blow up the raw material powder that has settled and deposited into the upper space (4), and the blade member (14b) located in the upper space (4) mainly operates in the upper space (4). It works to generate the air flow necessary to disperse and move the floating raw material powder.

The spray device (15) comprises a rotating container (1).
A spray nozzle (15a) fixed on the back surface of the fixed lid (8) and a liquid for supplying the binder liquid to the nozzle (15a). A pressure feed line (15b) is provided.

When starting the mixing of the raw material powder according to the present invention, the raw material powder (2) is supplied and deposited in the lower space (3) of the rotary container (1) as shown in FIG. Rotating container (1) and stirring device (14)
Is given rotation. Due to these rotations, an airflow is generated in the upper space (4) of the rotating container (1).

The rotating directions of the both may be the same or opposite directions, and the rotating speed of the rotating container (1) is relatively low, for example, about 50 to 100 times / minute is suitable. On the other hand, the stirring device (14) rotates at a high speed, and for example, about 1000 to 2000 times / minute is suitable.

The raw material powder in and around the rotation locus (16) (see FIG. 2) in which the tip of the blade member (14b) is drawn by the high-speed rotation of the stirring device (14) is mechanically stirred and mixed, and at the same time, the blade is blown. While being blown up by the high-speed rotation of the member (14b), it floats and disperses in the air flow in the upper space (4), gradually descends by its own weight with the passage of time, and then settles and deposits again in the lower space (3). To go.

The raw material powder settled and deposited is stored in a rotary container (1).
The same axis as the rotation of the container, the central axis of the container (1) (rotation center)
Since it moves around, it reaches the inside of the rotation locus (16) again during the movement and is blown up into the air while being mechanically stirred and mixed by the high speed rotation of the agitator (14), and then suspended and dispersed in the air again. . In this way, the raw material powder circulates between the upper and lower spaces (3) and (4) in the rotary container (1) by the rotation of the rotary container (1) and the high speed rotation of the stirring device (14). During the circulating movement, the lower space (3) is mechanically stirred by the device (14) and the upper space (4) is stirred by an air flow. Uniform mixing is possible without supplying pressurized air from the outside into the rotary container (1).

After a lapse of a predetermined time of the mixing operation, the rotation of the rotary container (1) and the stirring device (14) is stopped, and all the mixing operations are completed by waiting for the gravity-sedimentation separation of the suspended dispersed powder. .

Next, the granulation method of the present invention will be described.

According to the granulation method of the present invention, rotation of the rotary container (1) and high-speed rotation of the stirring device (14) installed at an eccentric position in the container (1) are carried out as in the above mixing method. Utilizing this, the raw material powder is circulated and moved between the upper and lower spaces (3) and (4) in the container (1), and during this circulatory movement,
The binder liquid is jet-supplied from the ceiling of the container (1) through the spray device (15). The binder liquid jetted and supplied into the rotary container (1) drops in the form of droplets from the ceiling, and during this drop, it adheres to the raw material powder suspended and dispersed in the upper space (4). While being attached to the raw material powder, the material is circulated between the upper and lower spaces (3) and (4).

When the supply of the binder liquid is continued,
Adhesion of the raw material powders to each other through the binder liquid and further granulation proceeds, and by continuing the supply of the binder liquid for a predetermined time, aggregates having a predetermined particle diameter can be obtained. By the way, even if the binder concentrates on the granules and the granules become large, they are divided by the action of the stirring blade, so that aggregates having a uniform particle diameter can be obtained. Further, the granulation of the raw material powder gradually progresses while the raw material powder circulates between the upper and lower spaces (3) and (4), so that almost no voids are generated between the adhered particles and the high density is achieved. Therefore, aggregates having a high bulk specific gravity can be obtained.

In order to make the particle diameters of the aggregates as uniform as possible, even after the supply of the binder liquid is stopped, for example, 1 to
It is desirable to continue the rotation of the rotary container (1) and the agitator (14), and thus the circulation of the raw material powder, for about 2 minutes.

After finishing the granulation of the raw material powder, when the rotation of the rotary container (1) and the stirring device (14) were stopped, all the raw material powder settled in the lower space (3) in the form of aggregates. Since it is deposited, it can be prepared for the next operation by removing it from the outlet (5) at the bottom of the container (1). The raw material powder may be either a single component or a multi-component, and in the case of multi-component, it can be granulated under a uniform mixed state.

Examples of powders include fine ceramic raw materials and powders of natural clay, and examples of binder liquids include PVA and water.

The particle size of the aggregate obtained by the present invention is 0.
It is about 1 to 3.0 mm, and aggregates having a desired particle size can be obtained by appropriately selecting the supply amount, type, concentration and the like of the binder.

In the mixing method and granulation method of the present invention, as schematically shown in FIG. 5, the circulation of the powder and the gas is controlled by the upper and lower spaces (3) in the rotary container (1). In addition to the circulation between (4), a circulation pipe (17) attached to the container (1)
The inside may be circulated by forced air blowing by a fan (18).

[0061]

According to the present invention, the following effects can be obtained.

A. This is a method in which powder and gas are repeatedly circulated and mixed in one closed container, so there is no need to supply pressurized air from the outside into the container, and a special means for separating powder and gas is provided. Does not require application.

B. Since the powder having a low specific gravity is not discharged at the same time by being accompanied by the pressure air supplied from the outside, all the powders are uniformly mixed in the container.

C. By the rotation of the container and the high speed rotation of the eccentric stirring blade, the powder freely moves and circulates in the container, so that uniform mixing can be performed.

D. Since the device is compact and the installation area can be reduced, various equipment is inexpensive.

E. Since mixing and granulation can be performed in a continuous process in one closed container, work efficiency is excellent and productivity is excellent.

F. Since it is a batch system and mixing or granulation work can be performed once, the quality is stable.

G. Since the powder is freely moved and circulated in the container by the rotation of the container and the high-speed rotation of the eccentric stirring blade, the granules can be uniformly granulated by simply spraying the binder liquid.

H. Due to the rotation of the container and the high-speed rotation of the eccentric stirring blade, even if it becomes a large aggregate, it is easy to obtain a spherical aggregate with uniform fluidity due to the "cutting" action of the stirring blade, and the spray time and work. 0.1mm by adjusting the time
Aggregates around ~ 3.0 mm are possible and functional.

I. The mixing time and the granulation time are extremely short.

(Approximately 1/30 the time of the ball mill system of the same scale) j. Uniform mixing and granulation are possible without being influenced by the raw material composition and ratio of powder, particle size, morphology, distribution, and the like.

K. We can support any powder industry such as ceramics, foods, chemicals.

[Brief description of drawings]

FIG. 1 is a vertical sectional view schematically showing the whole of an apparatus suitable for carrying out the method of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, omitting the raw material powder.

FIG. 3 is an explanatory view of the operation of a stirring device.

FIG. 4 is an explanatory view of the action of the rotary container.

FIG. 5 is a schematic explanatory view showing another embodiment of the method of the present invention.

[Explanation of symbols]

 1 Rotating Container 2 Raw Material Powder 3 Lower Space 4 Upper Space 5 Ejection Port 6 Lid Member 7 Upper End Opening 8 Fixed Lid Body 9 Input Port 10 Lid Member 11 Drive Device 12 Legs 13 Units 14 Stirrer 15 Sprayer 16 Rotation Trajectory

Claims (2)

[Claims] 1. A powder mixing method using a hermetic vertical rotary container that rotates about a central axis and a stirrer that is installed at an eccentric position in the rotary container so as to be free from rotation of the container. A method of carrying out a raw material powder deposited in the lower part of the rotary container while passing the eccentric installation position of the agitator while stirring and moving the raw material powder in the rotation direction as the container rotates, When passing, the raw material powder is blown up by the high-speed rotation of the stirrer to be suspended and dispersed in the upper space of the rotating container, and after the suspension dispersion, it is deposited on the lower part inside the container by gravity settling. According to the method, the raw material powder is circulated between the deposition position in the lower part of the container and the floating dispersion position in the upper part of the container. 2. A hermetically sealed vertical rotary container that rotates about a central axis and a stirrer that is installed at an eccentric position in the rotary container so as to be free from rotation of the container. A method of performing granulation, wherein the raw material powder deposited in the lower part of the rotary container is passed through an eccentric installation position of a stirring device while being stirred and moved in the rotational direction as the container is rotated, When passing through the position, the raw material powder is blown up by the high-speed rotation of the stirrer to float and disperse in the upper space of the rotating container, and the floating dispersed powder collides with the binder droplets spray-supplied in the upper space of the container. While aggregating with
A powder characterized in that the raw material powder is circulated between a deposition position in the lower part of the container and a floating dispersion position in the upper part of the container by repeating the above-mentioned steps, including the step of depositing in the lower part in the container by self-weight sedimentation. How to granulate the body.