JPH01317556A - Crushing and coating apparatus - Google Patents

Abstract

PURPOSE:To permit an efficient crushing and/or coating to be performed by providing a return particle amount adjusting means on a passageway through which the particles no recovered by a classifying part at the time of the classifying operation are sent back to a crushing part. CONSTITUTION:The subject apparatus is composed of a crushing part A for crushing materials by an air blast or stream, a classifying part B for classifying the particles of the materials crushed by the crushing part A, a passageway 6 for supplying the particles from the crushing part A to the classifying part B and a return passageway 7 for returning to the crushing part A the particles not recovered by the classifying part B at the time of the classifying operation. This return passageway 7 is provided with a return particle amount adjusting means 15 (e.g., jet nozzle). As a result, an efficient crushing and/or coating can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a crushing and coating device using a so-called jet mill, which is equipped with a crushing section and a classification section inside, and particularly relates to pharmaceutical products 1 and foods.

Dye, wax, resin pigment 1 synthetic resin, toner.

Powder and/or coating materials such as magnetic materials, organic/inorganic chemicals, mineral materials, ceramics, biochemical materials, etc. can be processed into high-pressure gases or gases at normal pressure and liquids at high pressures. subsonic speed, the speed of sound caused by the expansion of a gaseous body.

Or, it is an effective technique for energy-efficiently producing pulverized products with the desired particle size when the particles are supplied into a supersonic air stream and pulverized by the collision of particles with each other due to the intense shearing action of the air stream and particle acceleration. It is related to.

The present invention also provides a solution or melt of a coating material suitable for the crushing zone or classification zone of the jet nozzle, such as pigment 9 surfactant, wax, film agent, etc.
When coating a pulverized material by ejecting it from a coating material supply means, such as a two-fluid nozzle with an atomization function or other atomization equipment, or when coating is carried out at the same time as crushing and dispersing fine agglomerated powder, a high-quality coating material can be obtained. It relates to effective techniques that can be used to efficiently obtain.

[Conventional technology]

Among the so-called jet mills, a jet mill that has a kind of closed-circuit crushing mechanism that classifies the crushed material using an internal classification mechanism and returns particles coarser than a predetermined classification diameter to the crushing zone is disclosed in U.S. Patent No. 3, for example. .491.953 specification, JP-A-47-3791, JP-A-57-190
No. 656, JP-A-57-135052, JP-A-58-
137449, Japanese Unexamined Patent Publication No. 59-102455, etc.

Among these, for example, U.S. Patent No. 3.491°953
The so-called Jet-0-Mize disclosed in the specification of No.
The principle of the r-type jet mill is explained as follows. That is, this type of jet mill has a vertical 0-shape, and is structured to have a crushing zone at the bottom and a classification zone at the top. In this structure, the particles supplied from the feeder are supplied to the bottom of the 0 type by a supply jet feeder having a suction and crushing function.

Several jet holes are provided at the bottom of Type 0, and particles are pulverized in the jet flow ejected from the holes by the shearing action of high-speed airflow and mutual collision of accelerated particles. The crushed material rises through the ascending passage, is classified in the upper classification zone, and is divided into a predetermined classification diameter (cut 5ize) of the classification zone.
The larger coarse particles move down the return path and are returned to the bottom crushing zone where they are crushed together with the particles sucked and crushed by the feeding jet feeder.

In this recycling pulverization, the pulverized material is classified in a classification zone,
This process is repeated until the powder becomes fine powder with a predetermined classification diameter or less and is taken out of the system.

On the other hand, regarding grinding and coating using an opposed jet mill, for example, Japanese Patent Publication No. 48-42905, Japanese Patent Application Publication No. 58-13'7449, Japanese Patent Application Publication No. 59-10245
No. 5, Japanese Patent Publication No. 61-27104, and the like.

By the way, the principle of such a facing jet mill is explained as follows.

In other words, the opposed jet mill consists of a jet nozzle and an accelerating injector that suction and crush particles supplied from a feeder, and an opposed jet nozzle that suctions and crushes coarse particles and an opposed injector that suctions and accelerates the particles. The pulverization is performed by the suction collision action of the potential core of each jet nozzle and the head-on collision action in the pulverization zone of particles accelerated by the injector facing the jet nozzle. Then, the pulverized material is led to the classification zone through the pulverized material passage, and the swirling flow created in this zone loosens the fine powder and coarse particles, and the fine powder is taken out of the system from the discharge port as a pulverized product. It is collected by the installed dust collector. On the other hand, the coarse particles pass through the return path and are pulverized by the opposed jet nozzle and the opposed injector, and are further pulverized in the pulverization zone by colliding with the particles accelerated to be pulverized 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 classification diameter, and taken out of the system.

In addition, as described in Japanese Patent Publication No. 61-27104,
These jet mills can easily perform pulverization or coating of dispersed particles by providing a suitable coating material supply means in the pulverization zone or classification zone. The coating material supplying means may include, for example, a specially structured two-fluid nozzle that entrains and accelerates a solution of pigment 1 surfactant, wax, etc. as a coating material and atomizes it with high-pressure air, a coating material tank, and a pump. can.

[Problem to be solved by the invention]

However, these jet mills have a built-in classification mechanism, and these types of jet mills have the following problems.

In other words, to explain the grinding mechanism of a jet mill, first, particles collide with each other at an appropriate powder concentration, and if the impact force generated by the particle velocity at the time of collision is greater than the particle's fracture stress, the particles will be efficient. The former is called the collision probability and the latter is defined as the stress probability, but since these phenomena are independent events, the crushing efficiency is proportional to the product of the collision probability and the stress probability. I will do it.

For example, in order to increase the probability of collision, it is possible to increase the powder concentration in the crushing zone, but if this is too high, collisions will occur before particles are sufficiently accelerated, and the impact force at the time of collision will increase the fracture stress of the particles. It happens that it is smaller and not crushed. That is, although the probability of collision increases, the probability of stress decreases, so the crushing efficiency decreases. Conversely, if the powder concentration in the crushing zone is lowered in order to increase the impact force when particles collide, the impact particles will be crushed, but the probability of particle collision will decrease because the number of colliding particles is small. As the pulverization efficiency decreases, the pulverization efficiency decreases.

In other words, in order to increase the crushing efficiency, both the conditions of high collision probability and high stress probability are necessary, but this means that there is an optimal value range for the powder concentration in the crushing zone. There is.

Therefore, the present inventors conducted various experiments and found that the powder concentration (volume pace) in the crushing zone was 1 G-'~1(1'
It was found that the grinding efficiency was highest when the ratio was in the range of m'/m''.In order to maintain the powder concentration within this optimal condition range, it is generally necessary to The ratio of the return volume from the zone to the supply volume must be maintained between 1.5 and 3 (weight pace).

However, the above-mentioned jet mill with a built-in classification mechanism!
In both cases, particles coarser than the classification diameter of the classification section return to the crushing zone, so the powder concentration in the crushing zone is set to 10-3 to 10-'
It cannot be controlled within the range of m'/m'. Furthermore, when the supply amount is increased to increase the powder concentration in the crushing chamber, the powder concentration within the classification zone increases, the classification power decreases, the classification diameter increases, and the particle size of the crushed product becomes coarse. That is, the jet mill with a built-in classification mechanism cannot perform efficient grinding and/or coating.

The present invention was obtained as a result of intensive research aimed at fundamentally solving the above-mentioned problems of jet mills with a built-in classification mechanism.
The purpose is to provide a technique that allows efficient grinding and/or coating.

Other objects of the invention are to reduce contamination;
The object of the present invention is to provide a technique by which high-quality milled and/or coated products can be obtained.

Still another object of the present invention is to provide a technique capable of pulverizing and/or coating ultrafine particles.

[Means to solve the problem]

The grinding and coating device of the present invention uses jets or airflow to turn powder materials into fine particles.

Among jet mills that grind into fine particles and ultra-fine particles,
In a jet mill that has a classification mechanism inside, by providing a means for adjusting the return flow rate of coarse particles in the return passage for coarse particles from the classification section to the crushing section, the powder concentration in the crushing zone of the crushing section can be adjusted to the optimum powder concentration. concentration, preferably 10-' to 10-'
m'/m' (volume pace) is controlled.

As the return flow rate adjustment means, a jet nozzle or a ring nozzle is used to change the suction amount of powder by changing the air pressure, and a butterfly-shaped valve or damper member is provided, and the powder flow rate is adjusted by the opening degree of the valve. A means for adjusting the powder flow rate by providing an expansion/contraction material on the inner surface of the passage and changing the fluid pressure.A means for adjusting the powder flow rate by providing a movable baffle plate on the inner surface of the passage and changing the inclination angle of the baffle plate. There are means to adjust the

[Effect]

According to the above-mentioned means, the solids concentration in the grinding zone, that is, the powder concentration (volume basis), is adjusted to 10-' depending on the grindability and cut size of the material to be ground.
Since it can be controlled within the range of ~10-"m"/m", efficient pulverization and coating are possible.

These and other objects and advantages of the present invention will become more apparent from the following detailed description of the embodiments illustrated in the accompanying drawings.

〔Example〕

FIG. 1 is a schematic longitudinal cross-sectional view of the overall structure of an opposed jet mill-type pulverizer according to an embodiment of the present invention, in which a jet nozzle is provided in the coarse particle return passage, and FIG.
A schematic longitudinal cross-sectional view of the overall structure of a type 0 jet mill called Mizer in which a jet nozzle is provided in the coarse grain return passage, and FIGS. 3 to 6 are partial explanations of various embodiments of the coarse grain return passage. In the figures, Fig. 3 shows an example in which a ring nozzle is provided, Fig. 4 shows an example in which a butterfly valve is provided, Fig. 5 shows an example in which an expansion member is used, and Fig. 6 shows an example in which a buckle plate is used. It is.

The grinding and coating apparatus of the embodiment shown in FIG. 1 has an opposed jet mill type structure, and feeds powder and granule material supplied from a hopper 1 (particle supply source) connected to a quantitative feeder (not shown). It is configured to crush and/or coat by the impinging 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, substantially 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 stream from the jet nozzle 2.3 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 to the grinding zone is connected via a grinding material passage 6 for raising the grinding material to the classification zone B, which is connected via a coarse return channel 7 to the opposed jet nozzle 3.
It is connected to the jet stream passage in front of the.

The classification zone B is for classifying fine powder and coarse powder (coarse particles) by the swirling flow formed inside the classification zone B.The fine powder that has been pulverized to a predetermined classification diameter becomes a pulverized product approximately at the center of the classification zone B. It is discharged from the system through a discharge pipe 9 from a discharge port 8 on the back side of the section, and is collected by a product recovery device or a dust collector (not shown).

On the other hand, coarse particles that do not reach the desired classification diameter are sucked by the action of the jet nozzle 15 provided in the coarse particle return passage 7, accelerated by the opposed jet nozzle 3 and opposed injector 5, and centripetally balanced again in the crushing zone 8. After being crushed by crushing, it is sent to classification zone B. In this case, the return amount of coarse particles and fine powder is adjusted by adjusting the air pressure of the jet nozzle, and the powder concentration (volume basis) to the grinding zone is controlled to 10-'-10-"m'/m'. As a result, the optimum grinding condition can be maintained and the grinding efficiency can be greatly improved.

In this case, for powders that are easy to crush or relatively large classification diameters of several microns, the powder concentration should be reduced to 10-'m.
On the other hand, in the case of powders that are difficult to crush or have small classification diameters such as submicrons, it is best to control the powder concentration to around 10-3m'/m'. This is one measure of body concentration.

The embodiment shown in FIG. 2 has a so-called Jet-0-Mizer type jet mill structure, and the powder raw material is supplied from a hopper l (powder supply source) connected to a quantitative feeder (not shown). is sucked into the supply jet nozzle 2,
It is supplied to a crushing zone A formed by several jet holes 3a provided at the bottom of the 0 type. In the crushing zone 8, the particles are crushed by the shearing action of the high-speed airflow in the jet stream ejected from several jet holes 3a and mutual collision due to the speed difference of the accelerated particles. The crushed particles are conveyed through the crushed material passage 6 to the classification zone. In the classification zone B, coarse particles larger than this classification diameter are returned to the crushing zone B by the suction action of the jet nozzle 15 provided in the coarse particle return passage 7 as a return flow rate adjusting means. By adjusting the powder concentration in the grinding zone A, the powder concentration in the grinding zone A can be adjusted to the optimum concentration corresponding to the grindability of the ground material and the classification diameter, so that operation can be performed under optimum grinding conditions.

In addition, on the right side of FIG. 1 and FIG. 2, 10 is a high pressure gas source for supplying high pressure gas to the jet nozzle 2.3, 11.12 is a high pressure gas flow rate adjustment valve, 13.1
4 is a pressure gauge.

In the crushing and coating apparatus of this embodiment, a jet nozzle 15 as a return flow rate adjusting means is provided in the middle of the coarse particle return passage 7, and this jet nozzle 1
The high pressure gas to 5 is supplied from the high pressure gas source 10 to the flow rate regulating valve 1.
6.

By variably adjusting the flow rate of the high-pressure gas from this J-/) nozzle 15, the amount of powder sucked from the classification zone B to the coarse particle return passage 7 can be adjusted, and good pulverization efficiency can be obtained. be able to.

If the shape of the coarse particle return passage 7 shown on the right side of FIG. 1 and FIG. I can do it.

In other words, it is important to adjust the powder concentration (volume pace) in the crushing zone to a range of 10-' to 10-'m'/m' in order to keep the stress probability of crushing efficiency constant and increase the collision probability. However, with conventional jet mills, it is difficult to adjust the above-mentioned optimum powder concentration by changing the grinding speed and classification diameter, so the grinding efficiency reaches a plateau at a certain point.

On the other hand, in this embodiment, in order to improve this phenomenon, a jet nozzle 15 is used as a return flow rate adjusting means,
Since the optimum powder concentration can be selected, the grinding efficiency is improved. According to experiments, in the case of the present invention, good results have been obtained in that the throughput is increased by 1.5 to 2 times under the same crushing conditions as the conventional type.

As this return flow rate adjusting means, in addition to the jet nozzle 15 described above, various means as shown in FIGS. 3 to 6 can be used.

In the embodiment shown in FIG. 3, a ring nozzle 17 is provided at the entrance of the coarse particle return passage 7 as a return flow rate adjusting means, and a high pressure gas source 18 is provided.
By controlling the flow rate of high-pressure gas supplied to the ring nozzle 17 via the flow rate adjustment valve 19, an optimum powder return flow rate is ensured.

The embodiment shown in FIG. 4 uses a rotatable butterfly valve, ie, a damper member 20, as the return flow rate adjusting means. This damper member 2o includes a motor (not shown),
The return flow rate of the powder and granular material returned via the return passage 7 can be adjusted by rotating it by a desired angle with respect to the flow direction of the powder and granular material using an actuator or the like.

In the embodiment shown in FIG. 5, as the return flow rate adjusting means,
For example, an expansion member 21 made of rubber or resin is used to variably adjust the return flow rate through the coarse particle return passage 7 by expanding and contracting the expansion member 21.

The embodiment shown in FIG. 6 uses a baffle plate 22 whose opening degree can be adjusted by swinging as the return flow rate adjusting means. The inclination of the baffle plate 22 can be changed by adjusting the amount of air flowing through the coarse particle return passage 7, thereby adjusting the return flow rate of the powder through the coarse particle return passage 7.

As described above, according to the grinding and coating apparatus of this embodiment, the powder concentration in the grinding zone A is adjusted to the optimum level corresponding to the grindability and classification diameter of the ground material by the return flow rate adjusting means of the coarse particle return passage 7. Since the value can be maintained at a certain value, efficient grinding and coating can be performed.

Note that the present invention is not limited to the embodiments described above, but is applicable to a jet mill having an internal classification mechanism regardless of the classification mechanism, and a jet mill having a return path from the classification zone to the crushing zone. All can be applied to.

In addition, the material of the return flow rate adjustment means, jet nozzle, injector, discharge port, and main body of the device is iron.

In addition to metals such as stainless steel, it may also be made of rubber, plastic, or lined materials thereof, or wear-resistant materials such as alumina, corundum, silicon carbide, silicon nitride, and zirconia.

〔Effect of the invention〕

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

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

C) Since the grinding efficiency is high, submicron or nonamicron level secondary aggregates can be efficiently ground or disintegrated, and submicron or nonamicron 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) Due to the effects of (1) to (3) above, it is possible to efficiently perform ultrafine pulverization and coating of pharmaceutical products, foods, waxes, etc., which have a relatively low melting point and are susceptible to contamination.

(5) Furthermore, synthetic resins, toners, magnetic materials, mineral materials, ceramics, etc. that are difficult to crush can be efficiently crushed into ultrafine powder.

[Brief explanation of the drawing]

FIG. 1 shows a facing type jet which is an embodiment of the present invention. FIG. 2 is a schematic vertical cross-sectional view of the overall structure of a coarse particle return passage of a mill-type crushing and coating device in which a jet nozzle is provided as an example of a return flow rate regulating means. A schematic longitudinal cross-sectional view of the overall structure of a coarse particle return passage provided with a jet nozzle as a return flow rate adjustment means, and FIGS. 3 to 6 are portions of various other embodiments of the return flow rate adjustment means according to the present invention. Figure 3 shows an example using a ring nozzle, Figure 4 shows an example using a butterfly valve, Figure 5 shows an example using an expansion member, and Figure 6 shows an example using a baffle plate. FIG. 1... Hopper (powder supply source), 2... Supply jet nozzle, 3... Opposing jet nozzle, 3a... Jet hole, 4... Supply Injector, 5... Opposing injector, 6... Crushed material passage, 7... Coarse particle return passage, 8... Discharge port, 9... Discharge pipe, 10...High pressure gas source, 11.12...Flow rate adjustment valve, 13.14...Pressure gauge, 15...Jet nozzle (return flow! adjustment means), 16...Flow rate Adjustment valve, 17...Ring nozzle (return flow rate adjustment means), 1
8... High pressure gas source, 19... Flow rate adjustment valve, 20... Damper member (return flow rate adjustment means), 21
...Expansion member (return flow rate adjustment means), 22...
...Baffle plate (return flow rate adjustment means), 23...
Solenoid valve, 24...Air cylinder, A...Crushing zone, B...Classifying zone. Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Procedure (Hoshosho (self-proposal) July 19, 1988 Commissioner of the Japan Patent Office 1 Telegraph 11, Display of the case 1988 Patent application No. 149418 2, Name of the invention Grinding and coating device 3, Relationship with the amended case Patent applicant name Freund Sangyo Co., Ltd. 4, Agent 160 Address 7-21-21 Nishi-Shinjuku, Shinjuku-ku, Tokyo Seiwa Building 4th Floor 6, Claims column of the specification to be amended, Detailed explanation of the invention in the specification column, Brief explanation of the drawings column of the specification, Drawing 7, Contents of the amendment (1 ), the claims are amended as shown in the attached sheet. (2) The "adjusting means" on page 11, line 8 of the specification is amended as follows. ``Means for adjusting the powder flow rate by means of a return flow regulating object that is detachably inserted to obstruct the flow rate'' (3), ``Figure 6'' on page 12, line 6 of the specification is corrected to ``Figure 7'' (4)6 The “Example used” in lines 9 to 10 on page 12 of the specification is corrected as follows. Example" (5), "Figure 6" on page 17, line 14 of the specification is replaced with "Figure 7"
Correct it to ``Figure''. (6) Next to page 18, line 19 of the specification, add the following sentence: In the embodiments shown in FIGS. 7(a), 7a, and 7c, removable return flow rate regulating objects 25a, 25b, and 25c for inhibiting the return flow rate are provided in the return passage 7 as return flow rate regulating means, respectively. That is, these flow regulating objects 25a, 25b, 25
C is removably attached in the return passage 7 by means of attachment means (not shown), such as screws, but their positions are fixed in the attached state. And the return flow! The adjustment objects 25a, 25b, and 25c are different from the return flow rate adjustment means shown in FIGS. 3 to 6, which are of a variable adjustment amount type in which the return flow rate can be adjusted over the entire required range with one means. Famous object 25a. The amount of adjustment of the return flow rate for each of the objects 25b and 25c is constant, so to speak, the amount of adjustment is fixed, and these objects 25a, 25b. 25G can be exchanged and used depending on the adjustment of the return flow rate. In other words, in the case of Fig. 7, (a) in the same figure
, (C), and (C).
In case a), a relatively large return flow regulating object 25a
The passage cross-sectional area of the return passage 7 is narrowed down to a relatively large size using , and in the case of the same rlA(b), the return flow is approximately intermediate in size! The 11-node object 25b is used to adjust the flow rate to an intermediate amount of restriction, and in the case of CC) in the same figure, a relatively small return flow rate adjustment object is used to adjust the flow rate to a relatively small amount of restriction. It is. However, the return flow rate regulating objects are not limited to those shown in Figures 7(a), (b), and (e), and their size, shape, type, etc. may be arbitrary depending on the amount of adjustment and use. It can be adjusted to These return flow rate regulating objects 25a, 25b, and 25c have advantages such as simple structure, low cost, and easy installation and removal. ” (7), “Nona” on page 20 of the specification, line 5, right and line 7
Both are corrected to "nano". (8) Add the following sentence next to line 19 on page 20 of the specification. r (6), Claims 3 to 7 as a return flow rate adjusting means.
By using the variable adjustment amount type described in , if any of the return flow rate adjustment means is installed, the return flow rate can be adjusted in any range with just one. (7) By using the return flow rate adjusting object with a fixed amount of adjustment according to claim 8 as the return flow rate adjusting means, advantages such as simple structure, low cost, and easy installation are obtained. can get. Also, in this case, prepare return flow rate adjusting objects of different sizes and shapes.
By selectively using them depending on the amount of adjustment and the purpose, it is possible to perform multi-stage return flow rate adjustment substantially similar to the variable amount of adjustment type. (9), "Figure 6" on page 21, line 8 of the specification is amended to "Figure 7." 01, "Example used" on page 21, line 12 of the specification is amended as follows. "Example used, Figures 7(a), (b), and (C) are examples using a return flow rate regulating object." al) Next to page 22, line 17 of the specification, r25 a. 25b, 25c... return flow rate n-node object (return flow rate adjustment means)'' are added. Figure 7 (a), (b), (C
). (Above) 2. Claim 1: A pulverizing section that pulverizes granular material using a jet or air flow, a classification section that classifies the granular material pulverized in this pulverizing section, and a pulverized part that is pulverized in the pulverizing section A pulverizing and coating device comprising a pulverized material passage that supplies the granular material to the classification section, and a return passage that returns the granular material that has been classified and not collected in the classification section to the pulverizing section, A pulverizing and coating apparatus characterized in that the return passage is provided with a return flow rate adjusting means for returning powder and granules. 2. The grinding and coating apparatus according to claim 1, wherein the return flow rate adjusting means controls the powder concentration in the grinding zone of the grinding section by 10-' to 10-'m37 m''l.3. 4. The crushing and coating apparatus according to claim 1, wherein the return flow rate adjusting means is a jet nozzle. 4. The crushing and coating apparatus according to claim 1, wherein the return flow rate adjusting means is a ring nozzle. 5. The grinding and coating apparatus according to claim 1, wherein the return flow rate adjustment means is a damper member. 6. The return flow rate adjustment means expands and contracts by supplying and discharging fluid. The crushing and coating device according to claim 1, characterized in that it is an expansion member. 7. The return flow rate adjusting means is a baffle plate whose opening degree can be adjusted so as to adjust the inclination angle with respect to the flow of the returned powder and granular material. The crushing and coating device according to claim 1, characterized in that:

Claims (1)

[Scope of Claims] 1. A crushing section that crushes powder and granules using jets or air currents, a classification section that classifies the powder and granules that have been crushed in this crushing section, and powder particles that have been crushed in the crushing section. A pulverizing and coating device comprising a pulverized material passageway for supplying granular materials to the classification section, and a return passageway for returning granular materials that have been classified and not collected in the classification section to the pulverization section, the return passageway comprising: A grinding and coating apparatus characterized in that a return flow rate adjusting means for returning powder and granules is provided. 2. The return flow rate adjusting means adjusts the powder concentration in the crushing zone of the crushing section to 10^-^1 to 10^-^3m^3/m^2
The crushing and coating apparatus according to claim 1, characterized in that the crushing and coating apparatus is controlled to. 3. The grinding and coating apparatus according to claim 1, wherein the return flow rate adjusting means is a jet nozzle. 4. The grinding and coating apparatus according to claim 1, wherein the return flow rate adjusting means is a ring nozzle. 5. The grinding and coating apparatus according to claim 1, wherein the return flow rate adjusting means is a damper member. 6. The crushing and coating apparatus according to claim 1, wherein the return flow rate adjusting means is an expansion member that expands and contracts by supplying and discharging fluid. 7. The pulverization and coating apparatus according to claim 1, wherein the return flow rate adjusting means is a baffle plate whose opening degree can be adjusted so as to adjust the inclination angle with respect to the flow of the return powder and granules.