JPH02152559A - Pulverizing and coating device - Google Patents

Abstract

PURPOSE:To improve the pulverizing and coating efficiency of the pulverizing and coating device for which a jet mill having an internal classifying mechanism of a flat vortex type is used by specifying the ratio of the diameter of a discharge pipe/the diameter of a classifying zone to <=0.4. CONSTITUTION:The ratio of the diameter De of the discharge pipe/the diameter Di of the classifying zone of the pulverizing and coating device for which the jet mill having the internal classifying mechanism of the flat vortex type, i.e., the opposite type jet mill, is used is specified to <=0.4. More preferably, the discharge port 8 of the classifying chamber has the shape consisting of a curved surface or the combination of continuous lines in the inlet and the outlet part is made into the shape having an enlarged part. In addition, a pulverized product passage 6 entering the classifying zone B from a pulverizing zone A is so constituted that the gas and pulverized product flow into the passage from nearly the entire circumference. Further, the passage is so constituted that the gas and the pulverized product are admitted from the classifying circle C of the classifying zone B to the outer side. The pulverized product of a submicron class is easily obtd. by this constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention performs grinding and coating using a shedding mill having a flat vortex type internal classification mechanism, such as an opposed jet mill or a micronizer jet mill. It relates to equipment, especially pharmaceuticals, foods, dyes, waxes, resin pigments, synthetic resins, toners, and magnetic materials.

Organic/inorganic chemicals, mineral materials, ceramics, bio (
Powders such as biochemical materials and/or coating materials are supplied into a gaseous body at high pressure, or into a subsonic, sonic, or supersonic air flow generated by the expansion of gas that is gasified at normal pressure and liquefied at high pressure. This invention relates to a technique that is effective for producing fine particles or ultrafine particles by pulverizing the particles by colliding with each other due to the shearing action of airflow and particle acceleration.

Further, the present invention provides coating of the pulverized material or fine particles by spraying a solution of Pigment 5 surfactant, wax, film agent, etc. as the coating material from a two-fluid nozzle having an atomization function. The present invention relates to a technique that is effective when used to crush and disperse agglomerated powder and simultaneously perform coating.

[Conventional technology]

Typical types of jet mills with flat vortex internal classification mechanisms include opposed jet mills and micronizer jet mills. Each of these mechanisms will be explained below.

First, regarding grinding and coating using an opposed jet mill, for example, Japanese Patent Publication No. 48-42905, Japanese Patent Application Publication No. 58-137449, Japanese Patent Application Publication No. 59-102455
No. 61-27104, and the like.

The principle of this opposed jet mill is as follows. In other words, an opposed jet mill has a jet nozzle that suctions and crushes particles supplied from a feeder, a supply injector that suctions and accelerates the pulverized material, and an opposed jet nozzle that returns oppositely to each other on their center line and suctions and crushes coarse particles. and an opposed injector that accelerates suction.
Pulverization is performed by the suction collision action of the potential core of each jet nozzle and the head-on collision action of particles accelerated by the opposing injectors in the crushing zone, and the crushed material is guided from the crushed material passage to the classification zone, and the swirl created therein. The flow classifies fine powder and coarse particles, and the fine powder is taken out of the thread from the outlet as a pulverized product and collected by a dust collector. On the other hand, the coarse particles pass through the return path and are crushed by the opposed jet nozzle and the opposed injector, and are further crushed in the crushing zone by colliding with the particles accelerated to be crushed by the supply jet nozzle and the supply injector. This recycling pulverization is continued until the pulverized material is classified in the classification zone, turned into fine powder with a size smaller than the cut 5 size, and taken out of the system.

Next, regarding grinding and coating using a micronizer type jet mill, for example,
No. 905 and Japanese Patent Publication No. 56-78641.

The principle of this micronizer jet mill is explained as follows. In other words, a micronizer has multiple nozzles with a fixed spray angle (the angle formed by connecting the center of the mill and the center of the nozzle) on the peripheral wall of a crushing container with a circular cross section, and high-pressure gas is ejected from these nozzles. . The circle inscribed in the injection line of this jet creates a powerful swirling flow, and the area inside this circle becomes the classification zone.

Particles supplied from the feeder are suctioned and pulverized by a jet provided on the peripheral wall, and are conveyed to the rotating classification zone.

In this classification zone, particles finer than the cut size are taken out as pulverized products from the outlet through the thread as a pulverized product due to the inward flow created by the classification zone, and are collected by a dust collector.

On the other hand, coarse particles larger than the classification diameter are discharged from the classification zone to the peripheral wall by centrifugal force, are sucked and crushed again by a jet provided on the peripheral wall, and are returned to the classification zone and reclassified. This recycling pulverization is continued until the pulverized material is classified in the classification zone, turned into fine powder with a size smaller than the classification diameter, and taken out of the system.

In a jet mill having a flat vortex type internal classification mechanism as described above, an appropriate coating material supply means may be provided, as described in the aforementioned Japanese Patent Publication No. 61-27104, which discloses an opposed jet mill. This allows easy pulverization or coating of dispersed particles. The coating material supply means includes, for example, a pigment 1 surfactant as the coating material.

It can consist of a specially constructed two-fluid nozzle that entrains and accelerates a solution such as wax and atomizes it using high-pressure air, a coating material tank, and a pump.

[Problems to be Solved by the Invention] However, these conventional jet mills having a flat vortex type internal classification mechanism have the following problems.

(1) When attempting to obtain sub-micron particles efficiently, the classification diameter of the classification zone cannot be made small due to structural constraints, resulting in a decrease in pulverization and coating efficiency.

(2) When the classification flow changes direction at right angles at the exit pipe provided at the center of the classification zone, a vortex is generated and the classification diameter (
(cut 5ize) fluctuates, resulting in poor pulverization efficiency.

(3) In opposed jet mills, the pulverized material passage that connects the pulverizing zone and the classification zone is configured to flow tangentially into the classification zone, so that the airflow containing the pulverized material changes the powder concentration. The shape of the classification zone is distorted due to fluctuations in the inflow velocity, and the classification diameter fluctuates in a coarser direction. Therefore,
Classification accuracy deteriorates, and grinding efficiency and coating efficiency decrease.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the drawbacks of the conventional techniques described above and to provide a grinding and coating technique with high grinding and coating efficiency.

Another object of the present invention is to provide a pulverization and coating technique that enables fine pulverization or ultrafine pulverization with small classification diameters.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

The present inventors conducted intensive research to fundamentally solve the above-mentioned problems of jet mills having a flat vortex type internal classification mechanism, and as a result, they came up with the present invention. The coating equipment uses a jet mill with a flat vortex type internal classification mechanism.
The ratio of classification zone diameters is set to 0.4 or less.

Further, the crushing and coating apparatus of the present invention may have a structure in which the outlet of the classification chamber has a shape of a combination of curved lines or continuous straight lines at the inlet, and an enlarged part at the outlet. can.

Further, the crushing and coating apparatus of the present invention can be configured such that the crushed article passage through which the crushed article enters the classification zone from the crushing zone is configured such that the gas and the crushed article flow in from substantially the entire circumference.

[Effect]

According to the above-mentioned means, by making the ratio of the discharge pipe diameter/diameter of the classification zone 0.4 or less, or by making the shape of the discharge port of the classification chamber suitable for the vortex flow of the classification zone. As a result, there is almost no variation in the classification diameter, making it possible to efficiently produce and coat submicron particles.

Furthermore, since the shape is suitable for vortex flow, the pressure loss caused by sudden changes in flow direction is reduced, so the discharge port diameter can be made smaller, and as a result, submicron class classification can be performed efficiently.

Furthermore, by using a method in the mill in which the air flow containing the pulverized material flows uniformly from the entire circumference of the classification zone, the diameter of the classification is stabilized, allowing efficient pulverization and coating. becomes.

〔Example〕

FIG. 1 is a schematic vertical cross-sectional view of the overall structure of a grinding and coating device for an opposed jet mill that is an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view taken along the line ■-■ in FIG. 3 is an enlarged partial sectional view of one embodiment of the product discharge port in FIG. 2, and FIGS. 4(a) and 4(b) are views of micronizer-type crushing and coating equipment, which are other embodiments of the present invention, respectively. 5 is an enlarged partial sectional view of one embodiment of the product discharge port shown in FIG. 4;
The figure is a schematic longitudinal sectional view of the overall structure of a conventional opposed jet mill type grinding and coating device.

As is clear from FIG. 1, the crushing and coating apparatus of this embodiment has the structure of an opposed jet mill, and is supplied from a hopper 1 (powder supply source) connected to a quantitative feeder (not shown). The apparatus is configured to pulverize and/or coat the granular raw material by the collision action of opposing jet streams.

A supply jet nozzle 2 for sucking and supplying granular material and ejecting a jet stream, and a jet stream for ejecting a jet stream from the opposite direction to the jet stream from the supply jet nozzle 2 and sucking and entraining returning coarse particles. The opposing jet nozzles 3 are disposed facing each other on the same axis, that is, the same center line.

A supply injector 4 and a counter injector 5 for accelerating the jet stream from each jet nozzle 2.3 are interposed on the same axis between the pair of jet nozzles 2, 30.

Moreover, between both injectors 4 and 5, there is a crushing zone A.
is formed. In this crushing zone 8, the jet airflow from the jet nozzles 2 and 3 is transmitted to the injector 4.
．． 5 and collide head-on, and the powder raw material from the hopper 1 is pulverized and/or coated.

The upper side of the grinding zone A is connected to the classification zone B via a ground material passage 6 for raising the ground material. This classification zone B is connected via a coarse particle return passage 7 to a jet stream passage in front of the opposed jet nozzle 3.

The classification zone B is for classifying rJ fine powder and coarse particles by the swirling flow formed inside the classification zone B.The fine powder that has been pulverized to a predetermined classification diameter is produced as a pulverized product at approximately the center of the classification zone B. It is discharged out of the system from the discharge port 8 on the back side through the discharge pipe 9, and is collected by a product recovery device or a dust collector (not shown). On the other hand, coarse particles that have not reached the desired classification diameter are sucked by the opposed jet nozzle 3 from the classification zone B through the coarse particle return passage 7, accelerated by the opposed injector 5, and crushed again in the classification zone A. , sent to classification zone B. Such recycling of coarse particles is repeated until the coarse particles become fine powder with a classification diameter or less.

Regarding this point, in order to perform good classification, the present inventors have determined that, in order to improve the classification performance of the flat vortex classifier, the classification diameter fluctuates depending on the powder concentration, and that a classification diameter of right and submicron can be obtained. After examining the conditions for this, it was found that the former can be solved by stabilizing the classification zone (circle), and the latter can be solved by the shape of the outlet pipe suited to the flow pattern.

In other words, in a normal opposed jet mill (Fig. 6), an air flow containing pulverized material flows tangentially inside the classification zone (classification zone), so the blowing speed of this air flow into the classification and the powder Depending on the concentration fluctuation, the inside of the classification may be compressed, resulting in a smaller diameter or a distorted shape, and the shape may not be a normal circle. (opposite side) to form an elliptical shape.

If the flow pattern of such a classification zone changes,
The classification diameter gradually moves to the coarse grain side. In order to avoid this point, the powder supply rate is lowered and pulverization is performed under conditions that maintain normal classification, resulting in a significant drop in pulverization efficiency.

In order to solve this drawback, as in the embodiment of the present invention (Fig. 1), a flow path ( The inventors have discovered that it is possible to provide a full circumference inflow channel.

That is, in this embodiment, in order to allow the crushed material to flow outward from the tangential direction to the classification interior C of the classification zone B, the crushed material passage 6 is slightly wider than the vertical direction in FIG. It is slanted to the left.

According to this example, a stable classification zone is created without movement or deformation within the classification even if the inflow air velocity changes or an airflow with high powder concentration flows in, so that a product with a constant particle size can be processed using a known method. It can be produced in larger quantities more efficiently than a jet mill.

Furthermore, in this embodiment, the discharge port 8 of the classification zone B
The structure is also uniquely designed.

That is, during the pulverization coating, the airflow containing the pulverized material flowing from the pulverization zone 8 through the pulverized material passage 6 flows as a swirling flow within the classification zone B, and the particles dispersed in the airflow flow in this swirling flow. The state of movement is determined by the balance between the centrifugal force F caused by this and the force generated by the inward flow toward the discharge pipe 9.

In this case, if the particles are coarse, they will become FED and the classification zone B
The particles jump out further and move along the peripheral wall of the classification chamber, are suctioned and crushed by the opposed jet nozzle 3 from the rough flow return passage 7, are accelerated by the opposed injector 5, and further,
Grinding is performed by colliding with the feed particles accelerated by the feed jet nozzle 2 and the feed injector 4 in the grinding zone 8. On the other hand, fine particles become FED and are taken out from the thread as a pulverized product through a discharge pipe 9 connected to a discharge port 8 of the classification zone B. In this case, the particle size of F=D is called the cut size. In this way, the classification diameter is determined by the velocity ratio of the swirling flow and the inward flow, and this classification diameter is proportional to the square root of the ratio of the inner diameter of the discharge pipe 9 and the diameter of the classification zone B. It is known that it becomes smaller.

In this way, the ratio D-/D+ between the discharge pipe diameter and the classification zone diameter DI is an important factor that defines the classification diameter, and the smaller /DI is, the smaller the classification diameter is. In order to achieve efficient pulverization and improve classification performance when obtaining submicron-level pulverized material, D and /DI should be set to 0.
We would like to reduce it to about 2 to 0.15, but in the conventional opposed jet mill example, /D is 0.2.
If it is set to 0.15, air and powder will blow out from the hopper section 1 of the mill, making it impossible to continue operation. Alternatively, since a large back pressure is applied to the discharge port side, the speed of the jet stream decreases, and the crushing performance decreases significantly.

Therefore, in this embodiment, as shown in FIGS. 2 and 3, a discharge port member 25 is provided at the entrance of the discharge pipe 9 connected to the discharge port 8. The inlet 1llIS25a of this discharge port member 25 is shaped as a continuous curved surface or a combination of straight lines, the classification is made close to an Archimedean vortex suitable for the purpose of classification, a cylindrical part 25b is provided in the middle, and the outlet part 25C is In order to recover the energy of the jet flow at the discharge part, the enlarged part has an enlarged angle θ. By providing the outlet member 25 with this structure, D, /D.

It can be operated even if the ratio is lowered to about 0.15, and a clean classifier can be produced, so submicron particles can be efficiently produced. Also, several μm or tens of μm
When it is desired to obtain a pulverized product, replacing the discharge port member 25 with one having a larger inner diameter increases the classification diameter, making it possible to efficiently obtain a product with the desired particle size.

Next, the crushing and coating apparatus in the embodiment shown in FIG. 4 has a micronizer-type jet mill structure, and the granular raw material is connected to a quantitative feeder (not shown) and is supplied from a hopper through a supply jet nozzle. It is configured to be suction-pulverized and supplied to a crushing and classification chamber, where it is crushed and/or coated.

Since the plurality of nozzles provided on the peripheral wall 17 of the crushing and classifying chamber 18 are provided at a constant spray angle θ with respect to a line connected to the center of the crushing chamber, a powerful classification is performed on the circle inscribed in the jet line of this jet stream. Since the machine (doughnut-shaped classifier indicated by the dashed dotted line) 19 is configured, the outside of this classifier 19 is the crushing zone A1, and the inside zone up to the discharge port 8 is the classification zone B.

A ring-shaped high pressure air chamber 15b and a high pressure air inlet 15a are provided on the outside of the peripheral wall 17 of the crushing and classification chamber 18, and a control valve 12. High-pressure air is blown into the crushing and classification chamber 18 through the pressure gauge 14, creating a high-pressure jet stream. In addition, a part of the high pressure air is supplied to the control valve 11 and the pressure gauge 13.
is fed to the feed jet feeder through.

The powder and granular material supplied from hopper 1 is fed to supply jet nozzle 2.
It is suctioned and crushed by the suction action of and supplied to the crushing zone 8 of the crushing and classification chamber 18. In the crushing zone 8, the powder is suctioned and crushed by a nozzle 16 provided on the peripheral wall 17, and is conveyed to a classifier that rotates at high speed. In classification zone B, as mentioned above, particles smaller than the classification diameter created by the high-speed swirling flow are directed toward the center of the classification zone, and are taken out of the thread through the discharge port 8, where they are processed into pulverized products by another collection device (not shown). It will be collected. Particles larger than the classification diameter are repelled by centrifugal force from the swirling flow and transported to the crushing zone. The particles are sucked and pulverized by a jet stream from a nozzle provided on the peripheral wall, and returned to the classification zone. Such recycling of the crude stream is repeated until the crude stream becomes a fine powder with a size smaller than the classification diameter.

The present inventors attempted to provide the discharge port member 25 based on the same principle as the opposed jet mill in the flat vortex type internal classification mechanism described above.

FIG. 5 is a detailed explanatory diagram of the discharge port member 25 attached to the discharge port 8 of the micronizer type jet mill shown in FIG. In this case, the discharge outlet member 25 is provided vertically, and the details thereof are the same as those in FIG.
is a curved surface or a combination of continuous straight lines, a cylindrical part 25b is provided in the middle, and the outlet part 25c is an enlarged part with an expansion angle θ to recover the energy of the jet flow, and the expansion angle is generally A range of 5° to 15° is used, with the optimum value being 7° to 8@.

By providing this discharge member 25, the speed of the classifier can be increased because it rectifies the flow and minimizes energy loss due to change in flow direction. As a result, pulverization can be performed even if the ratio of D-/D+ is reduced to about 0.15, so submicron-sized powder can be efficiently produced by pulverization.

As described above, according to the crushing and coating apparatus of this embodiment, the ratio of the discharge pipe diameter/classification zone diameter can be arbitrarily selected to be 0.4 or less. That is, the classification diameter is 5 to 10 μm, the exit pipe diameter is 0.3 to 0.4, the /DI ratio is 0.3 to 0.4, and the classification diameter is 5.
For micrometers or less, an exit pipe diameter with a D-/D+ ratio of 0.2 to 0.3 is used, and for submicron class diameters, an exit pipe diameter with a D-/D+ ratio of 0.2 or less is used. In this way, since the classification size corresponding to the particle size of the pulverized material can be selected, efficient pulverization and coating can be performed.

By making the shape of the classification circle discharge port 8, that is, the population and exit shape of the discharge port 8 inserted into the discharge pipe 9, suitable for the flow of the classification zone B, the classification diameter can be made small. It is possible to efficiently create and coat submicron particles.

In addition, since the energy loss due to the change of direction of the flow at the outlet is reduced, the back pressure of the jet in the crushing zone is reduced, so that the jet is sufficiently expanded and a high jet velocity is obtained. Therefore, the grinding efficiency is significantly improved.

Furthermore, in opposed jet mills in which the crushing zone and classification zone are separated, the flow path entering the classification zone is configured so that it flows uniformly over the entire circumference of the classification zone, so the inflow speed and powder concentration are Since the classification zone is not reduced or deformed by the process, precise classification can be performed, and grinding and coating can be performed efficiently.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be applied to a grinding and coating apparatus using a jet mill having a flat vortex type internal classification mechanism, a vertical type,
In case of horizontal or inclined arrangement, 1 ratio of the shape of the classification zone or crushing zone.

It can also be applied when changing the position etc.

In addition, the materials for the nozzle, injector, discharge port, and device body include metals such as iron and stainless steel, as well as rubber, plastic, and linings thereof, and wear-resistant materials such as alumina, corundum, silicon carbide, silicon nitride, and zirconia. It may be something that is made.

〔Effect of the invention〕

According to the configuration of the present invention as described above, the following effects can be obtained.

(1) Since the pulverization efficiency is increased, the power required for pulverization can be significantly reduced, and the cost required for pulverization can be reduced.

(2) Since the grinding efficiency is high, submicron or nanomicron level secondary aggregates can be efficiently ground or disintegrated, and submicron or nanomicron level coatings can be easily formed.

(3) High grinding efficiency, cut 5ize
can be transferred to a small particle size, making it possible to easily obtain submicron-level pulverized and/or coated products.

(4) According to the results of (1) to (3) above, pharmaceutical 1 food has a relatively low melting point and is averse to adhesion and contamination.

Ultrafine pulverization and coating of waxes can be carried out efficiently.

(5) Also, synthetic resins that are difficult to crush, toner, f! It is possible to efficiently pulverize materials such as mineral materials, mineral materials, and ceramics into ultrafine powder.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of the overall structure of a grinding and coating device for an opposed jet mill that is an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view taken along the line ■-■ in FIG. 3 is an enlarged partial sectional view of one embodiment of the product discharge port in FIG. 2, and FIGS. 4(a) and 4(5) respectively show micronizer-type crushing and coating equipment according to other embodiments of the present invention. 5 is an enlarged partial sectional view of one embodiment of the product discharge port shown in FIG. 4;
The figure is a schematic longitudinal sectional view of the overall structure of a conventional opposed jet mill type grinding and coating device. 1... Hopper, 2... Supply jet nozzle, 3... Opposing jet nozzle, 4... Supply injector, 5... Opposing injector, 6... ...Crushed material passageway, 7... Coarse particle return passageway, 8 . . . . . 9 . . . . 10 . ... D, ・ ・ ・ DI ・ ・ ・ ・Discharge port, ・Discharge pipe, ・High pressure gas source, ・Flow rate control valve, ・Pressure gauge, ・High pressure gas inlet, ・High pressure gas ring, ・Crushing nozzle, ・Crushing chamber surrounding wall , ・Crushing/classifying chamber, ・Virtual classification circle, ・Discharge port member, ・Popular part, ・Cylinder part, ・Exit part, ・Crushing zone, ・Classifying zone, ・Classifying circle, ・Discharge pipe diameter, ・Classifying zone diameter . Figure 1 Figure 2 Shinige 1 East - Figure 4 (a) Figure

Claims (1)

[Claims] 1. A grinding and coating device using a jet mill with a flat vortex type internal classification mechanism, characterized in that the ratio of discharge pipe diameter/classification zone diameter is 0.4 or less. Grinding and coating equipment. 2. The crushing and coating device according to claim 1, wherein the discharge port of the classification chamber has a curved surface or a combination of continuous straight lines at the inlet, and an enlarged outlet at the outlet. . 3. The pulverization and coating apparatus according to claim 1 or 2, wherein the pulverized material passageway through which the pulverized material enters the classification zone from the pulverization zone is configured such that the gas and the pulverized material flow in from substantially the entire circumference. . 4. The pulverization and coating apparatus according to claim 3, wherein the pulverized material passage is configured to allow gas and pulverized material to flow outside the classification circle of the classification zone.