JPH08182966A - Pneumatic classifier - Google Patents

Abstract

PURPOSE: To prevent the turbulence of a classifier air current at the tip of a classifying edge and to perform classifying with high accuracy by an accurate classifying point by fascilitating setting of the classifying edge at an optimum position. CONSTITUTION: On lower side walls 23, 25 of side wall blocks 22-24, classifying edges 17, 18 are provided. In the lower part of the side wall block 22, a raw material feeding pipe 16 opened to a classifying chamber 32 is installed. Besides, a core bloc 26 bent downward in the shape of a long ellipse connected to the extention of the tangent line of the bottom of the pipe 16 is installed. In an upper wall 27 of the classifying chamber, an intake air edge 19 of knife edge type is provided on the lower part on the classifying chamber 27 side, and intake air pipes 14, 15 opened to the classifying chamber 32 are installed across the upper wall 27 of the classifying chamber. The pipes 14, 15 are provided with the 1st and the 2nd gas introducing adjusting means 20, 21 and static pressure meters 28, 29, respectively. The classifying edges 17, 18 and the intake air edge 19 can be rotated and set to a desired position. Since a classifying point is thus set accurately, powder having sharp particle size distribution is effective produced, and also there in no variation in the classifying point, and in addition, the change width of the classifying point is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow classifier for classifying powder raw materials by utilizing the Coanda effect. More specifically, the present invention relates to a powder having a weight average particle size of 20 .mu.m or less.
Based on the Coanda effect, the difference in inertial force, centrifugal force, etc. according to the particle size of each particle in the powder material, while classifying the powder material containing more than a few percent by number and carrying the powder in the air stream. The present invention relates to an airflow classifier capable of efficiently classifying particles having a predetermined particle size.

[0002]

2. Description of the Related Art For classifying powder raw materials, various airflow classifiers and airflow classifying methods have been proposed. Among them, classifiers using rotary blades and classifiers having no moving parts are proposed. is there. Among them, as a classifier without moving parts,
There are fixed wall centrifugal classifiers and inertial force classifiers. As a classifier capable of classifying in the fine powder region using such inertial force, Lo
ffler. F. and K. Maly: Symposs
ium on Powder Technology
D-2 (1981), an elbow jet classifier commercialized by Nippon Steel Mining Co., Ltd., Okuda.
S. and Yasukuni. J. : Proc. In
ter. Symposium on Powder T
There is a classifier exemplified and proposed in technology '81, 771 (1981). FIG. 5 shows a sectional view of a classification chamber of a conventional classifier utilizing inertial force, and FIG. 6 shows a perspective view thereof. In the conventional airflow type classifier shown in these figures, first, the powder raw material is jetted at high speed into the classification area together with the airflow from the outlet of the raw material supply pipe 116 having an opening in the classification area of the classifier chamber 132. To be done. A Coanda block 126 is provided in the classification chamber 132, and the air inlet 11
4 and 115, by introducing an airflow that intersects the airflow ejected from the outlet of the raw material supply pipe 116 at an angle, the centrifugal force of the curved airflow flowing along the Coanda block 126 causes the powder to flow, as shown in FIG. The body material is separated into coarse powder, medium powder and fine powder, and the classification edge 11 has a thin tip.
7 and 118 classify coarse powder, medium powder and fine powder.

However, the conventional classifier 101 as described above has the following problems. That is, in the conventional classifier 101, the side wall blocks 123 and 125, which are classification edge blocks, and the side wall block 12 on the coarse powder side.
4 (hereinafter, simply referred to as a coarse powder side block) are fixed respectively, the tip positions of the classification edges 117 and 118 are adjusted, and the flow rate of the air flow for classification is adjusted accordingly, so that the classification point (That is, the size of the particle that becomes the boundary of classification) is set to a predetermined value. Further, the specific gravity of the powder and the tip positions of the classification edges 117 and 118 corresponding to a predetermined classification point are detected and moved, and the air flow is controlled so that the predetermined flow rate is obtained accordingly. However, if only adjusting the tip positions of the classification edges 117 and 118 as in the conventional art, the turbulence of the air flow is likely to occur near the tip ends of the edges depending on the angle, and as a result, accurate classification cannot be performed. In some cases, particles having a size that should be uniform should originally be mixed with particles having a size that should be in another particle group. Further, even if the tip positions of the classification edges 117 and 118 are changed and the flow rate is controlled to a predetermined flow rate in accordance with the change of the classification point, the position of the classification edge is not controlled along the air flow direction. In the end, there is a problem to be improved such that not only it takes time to adjust the classification point to a predetermined value but also the classification accuracy is lowered.

In particular, the above-mentioned problems were remarkable in the classification carried out in the case of manufacturing the toner for developing an electrostatic image used in a copying machine, a printer or the like. Toners generally require many different properties. In order to obtain the required performance, the raw materials to be used are, of course, examined, and the difference in the manufacturing method often affects the characteristics of the toner, and it is necessary to thoroughly study the manufacturing method. In the classification step during toner production, classified particle groups are required to have a sharp particle size distribution. Further, it is desired to produce a high-quality toner efficiently and stably at low cost.

Generally, as a binder resin used as a constituent material of a toner, a resin having a low melting point, a low softening point and a low glass transition point is used as the binder resin. When the powder containing such a resin is introduced into a classifier and classified, there is a problem that adhesion or fusion in the classifier is likely to occur. On the other hand, in recent years, for example, even when a soft binder such as wax is used as the binder resin in order to fix it on the recording material by pressure as a measure to save energy in a copying machine, or even when heat fixing is performed. In order to increase the fixing speed, reduce the power consumption required for fixing, and fix at a low temperature, a binder resin having a low glass transition point or a low softening point has been used.

Further, in recent years, in order to improve image quality in copying machines and printers, required toner particles are gradually becoming finer. Generally, as the substance becomes finer, the action of the interparticle force increases, but the same applies to the case of resin particles and toner particles, and when the substance has a small size, the cohesiveness of the particles increases. Further, the mass difference between the particles also becomes smaller. When an external force such as an impact force or a frictional force acts on such an agglomerate, the particles are likely to generate a fused substance in the classifying device. In particular, fusion is likely to occur at the tip of the classification edge, and when such a phenomenon occurs, the classification accuracy deteriorates and the classification device is not operating in a stable state at all times, so a high-quality classified product can be obtained for a long period of time. Becomes difficult.

In particular, when a toner having a sharp particle size distribution is to be obtained from a toner raw material having a weight average particle diameter of 10 μm or less, there is a problem that a conventional classification device causes a reduction in classification yield. Furthermore, the weight average diameter is 8μ
When a toner having a sharp particle size distribution is to be obtained from a toner raw material having a particle size of m or less, the conventional apparatus described above remarkably causes a decrease in classification yield. From these points, fine powder, especially resin fine powder such as toner,
An airflow classifier capable of stable and efficient classification is desired.

[0008]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an air flow type classification device which solves the problems of the prior art. That is, an object of the present invention is to provide an air flow type classification device capable of more accurately classifying by setting an accurate classification point and efficiently generating powder having a fine particle size distribution. is there. Another object of the present invention is to provide an airflow type classification device capable of stable classification without causing fusion or the like in the classification chamber and causing no change in the classification point in the device. It is in. Further, it is an object of the present invention to provide an airflow type classification device having a large change range of classification points. Further, it is an object of the present invention to provide an airflow type classification device which can change the classification point in a short time. It is another object of the present invention to provide an airflow classifier which can efficiently obtain a classified product having a sharp particle size distribution from a powder raw material having a weight average diameter of 10 μm or less. In particular, it is an object of the present invention to provide an airflow type classification device which can efficiently obtain a classified product having a sharp particle size distribution from a toner raw material having a weight average diameter of 8 μm or less.

[0009]

The above object is achieved by the present invention described below. That is, the present invention has at least a classification area formed by a Coanda block, a side wall block and a plurality of classification edges, and the powder raw material supplied from the raw material supply pipe in the classification area is at least a coarse powder due to the Coanda effect. Group, medium powder group and fine powder group are classified by air flow type, the side wall block side of the coarse powder group is configured to be movable so that the shape of the classification area can be changed. It is an air flow type classifier characterized by the fact that it is.

[0010]

According to the present invention, since the classification edge can be easily set to the optimum position, the turbulent flow of the classification airflow at the tip of the classification edge can be effectively prevented, and the specific gravity of various powders and the classification airflow conditions can be improved. According to the above, a toner having a sharp particle size distribution can be obtained with a high classification yield according to the above, and abrasion of the apparatus due to toner components can be prevented, and continuous and stable production can be performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings by taking as an example a gas stream classifier for dividing the powder material of the present invention into three parts. As a specific example of the airflow classifier of the present invention, FIG. 1 shows a cross-sectional view of the vicinity of a classification chamber 32 of a three-division airflow classifier, and FIG. 2 shows a perspective view thereof. In FIGS. 1 and 2, reference numerals 22, 23 and 24 denote side wall blocks, respectively. As shown in the figure, the lower side wall has a shape shown by 23 and 25, and is provided with knife edge type classification edges 17 and 18, respectively.
According to 8, the classification area of the classification chamber 32 is divided into three. However, the present invention is not limited to this, and the classification chamber 32 is divided into arbitrary classification regions by changing the number of classification edges. Further, in the air flow classifier of the present invention, as shown in FIGS. 1 and 2, a raw material supply pipe 16 having an opening in a classifying chamber 32 is provided below a side wall block 22 at the upper part, Further, a Coanda block 26 is installed which is bent downward with respect to the direction of extension of the bottom tangent line of the raw material supply pipe 16 to draw an elliptical arc.

As shown in FIGS. 1 and 2, the upper wall 27 of the classification chamber is provided with a knife-edge type air inlet edge 19 in the lower portion on the side of the classification chamber 32, and further the upper wall 27 of the classification chamber is provided. Air inlet pipes 14 and 15 which are sandwiched and open to the classification chamber 32 are provided. The inlet pipes 14 and 15 are provided with first and second gas introduction adjusting means 20 and 21 such as dampers, and
Static pressure gauges 28 and 29 are provided. In the airflow classifier of the present invention, the installation positions of the classification edges 17 and 18 and the air intake edge 19 as described above are adjusted depending on the kind of powder as the raw material to be classified or the desired particle size. . That is, the classification edges 17 and 18 and the intake edge 19
Respectively, as shown in FIG. 1, respectively shafts 17a, 18a and 1
It is configured to be rotatable around 9a, and the edges can be rotated around these axes to set the tip of each edge to a desired position.

Further, in the air flow type classifier of the present invention, the setting position of the coarse powder side block 24, which is the side wall on the coarse powder side fixed in the conventional apparatus, is also movable so that classification is performed. The setting position can be changed depending on the type of powder of the processing raw material and the desired particle size. As a result, in the present invention,
By appropriately determining the setting position of each edge of the classification edges 17 and 18 and the air intake edge 19 and the setting position of the coarse powder side block 24, each classification region of the classification chamber 32 is set as described later. It can be set arbitrarily and easily. The movement of the position of the coarse powder side block 24 is preferably
Move horizontally or almost horizontally. For this reason, as shown in FIGS. 1 and 2, it is preferable to provide a position adjusting means capable of moving horizontally and to carry out the external movement by using a stepping motor or the like.

Further, the bottom of the classification chamber 32 is provided with an outlet corresponding to each fractionation area, for example, as shown in FIG.
In the example of FIG.
2 and 13 are provided. These discharge ports may be connected to communication means for communicating the discharge ports with each other, and each may be provided with an opening / closing means such as a valve means.

Raw material supply pipe 1 having an opening in the classification chamber 32
6 may have any structure as long as it is capable of ejecting the raw material divided material into the classification chamber 32 through the opening portion. For example, a straight pipe tubular portion as shown in FIGS. 1 and 2. 16a
And a pyramidal cylinder portion 16b whose tip is an opening to the classification chamber 32 following this. Also, the inner diameter of the straight pipe cylinder and the narrowest part of the pyramid cylinder (classification chamber 32
When the ratio of the inner diameter of the opening) is set to 20: 1 to 1: 1 and preferably 10: 1 to 2: 1, a good ejection speed of the raw material segmentation can be obtained.

Further, the raw material supply pipe 16 together with the powder raw material is supplied with the air flow.
The means for feeding into is not limited to any, but for example, a method of sending by applying a pressure of about 0.09 to 0.29 MPa, a blower is provided on the downstream side of the classification area, and classification is performed by enlarging it. A method of naturally sucking the outside air and the powder raw material by increasing the negative pressure in the area, or connecting the raw material supply pipe 16 which is an input port of the powder raw material and mounting an injection feeder, There is a method in which the powder raw material and the outside air are sucked by the method, and the powder raw material is sent to the classification area through the raw material supply pipe 16. In the present invention, among the above-mentioned three powder feeding means, in particular, a method of increasing the negative pressure in the classification area to naturally suck the outside air and the raw material powder, and a method of mounting an injection feeder are used. In terms of performance, there is a positive effect on operating conditions.

The classification operation in the multi-division (three divisions in the illustrated example) classification area configured as described above is performed, for example, as follows. That is, by decompressing the inside of the classification chamber 32 via at least one of the discharge ports 11, 12, and 13, the raw material supply pipe 16 having an opening into the classification chamber 32 is decompressed, and the decompression results. An air flow is generated in the raw material supply pipe 16 by the flow. The speed of the flowing air flow is not limited in the present invention, but the flow speed is preferably 50-
The powder raw material is supplied into the classification chamber 32 through the raw material supply pipe 16 at a speed of about 300 m / sec. The powder raw material supplied by the above means has the Coanda effect due to the operation of the Coanda block 26 provided at the lower part of the raw material supply pipe 16 and the operation of gas such as air flowing into the classification chamber 32 at that time. Move in a curved line 30 due to, and depending on the particle size of each particle and the magnitude of the inertial force, the large particles (coarse particles) are outside the air flow, that is, outside the classification edge 18, as indicated by 30a. Intermediate particles (particles with a size within the standard) move to the first fraction area as shown by 30b, and smaller particles (particles with a standard particle size or less) into the second fraction area between the classification edges 17 and 18. The particles) move like 30c and are classified into the third fraction area inside the classification edge 17, respectively. Then, large particles are discharged from the discharge port 11, intermediate particles are discharged from the discharge port 12, and small particles are discharged from the discharge port 13, respectively.

In the classification of the powder raw material according to this embodiment,
The classification point is the classification edge 17 with respect to the left end portion of the Coanda block 26, which is the position where the powder jumps out into the classification chamber 32.
And 18 respectively. Further, the classification point is affected by the flow rate of the classification airflow, the ejection speed of the powder from the raw material supply pipe 16, and the like. In the gas stream type classifier of the present invention, when the powder raw material is introduced into the classifying chamber 32, it is dispersed according to the size of the particles in the powder to form a particle flow. Therefore, a predetermined classification point can be set by first moving the coarse block 24, which is a side wall on the coarse powder side, along the streamline and fixing the tip positions of the classification edges 17 and 18. I can. Such movement of the classification edges 17 and 18 and the coarse powder side block 2
With the movement of 4, the direction of the classification edge can be aligned with the flow direction of each particle group flying along the Coanda block 26.

FIG. 4 shows an enlarged view of the vicinity of the classification chamber 32 shown in FIG. Specifically, as shown in FIG. 4, for example, the side wall of the Coanda block 26 is centered around the point O which is a position in the Coanda block 26 corresponding to the lower part of the opening at the tip of the raw material supply pipe 16. Distance a from coarse powder side block 24
Can be adjusted by moving the coarse powder side block 24 horizontally or substantially horizontally along the positioning member 33.
Further, the distance c between the tip of the classification edge 17 and the wall surface of the Coanda block 26 can be adjusted by rotating the tip of the classification edge 17 about the shaft 17a. Similarly, the distance b between the tip of the classification edge 18 and the wall surface of the Coanda block 26
Can be adjusted by rotating the tip of the classification edge 18 about the shaft 18a. That is, with the change of the block on the coarse powder side, the shape of the classification area of the classification chamber changes,
It is possible to easily and significantly adjust the classification point.
As the particle size decreases, the difference in mass between powder particles also decreases.Therefore, in an air flow classifier that uses centrifugal force and inertial force, the flight trajectory of particle groups that depends on the mass of powder The width became narrower, and there was a tendency that particles did not reach the vicinity of the block on the coarse powder side. However, in this apparatus, by moving the coarse powder side block 24 in accordance with the specific gravity / classification point of the coarse powder raw material, the width of the trajectory of the particle group is widened, the classification yield is improved, and stable classification is performed on the apparatus. It becomes possible to do.
Further, fusion of the tip of the classification edge tends to be reduced.
Furthermore, the flow turbulence at the tip of the classification edge can be prevented, and the flow rate of the suction flow due to the reduced pressure through the discharge conduits 11a, 12a, 13a is adjusted to increase the flight speed of the particles and to reduce the powder in the classification region. Not only can the dispersion of the body be improved, it can be obtained with higher dust concentration with good classification accuracy, and not only the decrease in product yield can be prevented, but also the same dust concentration can improve better classification accuracy and product yield. Is possible.

Further, the tip of the air inlet edge 19 and the Coanda block 26 are centered around, for example, the position O in the Coanda block 26 corresponding to the lower portion of the tip opening of the raw material supply pipe 16.
The distance d to the side surface of the air intake tube can be adjusted by rotating the tip of the air intake edge 19 around the shaft 19a of the air intake edge 19, whereby the air intake tubes 14 and 1 can be adjusted.
By adjusting the inflow rate and the inflow rate of gas from 5,
Further adjustment of the classification point becomes possible. The edge installation system as described above may be determined according to the properties of the powder to be treated, and is not limited at all. For example, when classifying a toner raw material, the weight particle diameter of the raw material is 1
It is also effective in the case of 0 μm or less, and is particularly effective in the case of 8 μm or less.

In order to carry out the above-mentioned method, it is usual to use an integrated device system in which mutual devices are connected by a communication means such as a pipe. A preferred example of such a device system is shown in FIG. The integrated device system shown in FIG. 2 is a three-division classifier 1 (shown in FIGS. 1 and 2 and details are as described above), a constant quantity feeder 2, a vibration feeder 3, a collection cyclone 4, 5 and 6 are connected by a communication means.

In the apparatus system shown in FIG. 2, the powder raw material which is a pulverized product pulverized by a collision type air flow pulverizer or the like is
First, it is fed into the constant quantity feeder 2 by an appropriate means, and then the raw material supply pipe 16 is used to feed 3 through the vibrating feeder 3.
It is introduced into the division classifier 1. Upon introduction, 50 ~
The pulverized material is introduced into the three-division classifier 1 at a flow rate of 300 m / sec. The size of the classification chamber of the three-division classifier 1 is
For example, since it is usually 10-50 cm x 10-50 cm,
The divided raw material which is a pulverized product can be classified into three or more kinds of particle groups in an instant of 0.1 to 0.01 seconds or less. In the example of FIG. 2, the powder raw material is divided into three particles by the three-division classifier 1 into large particles (coarse particles), intermediate particles (particles with a specified particle diameter) and small particles (particles with a specified particle diameter or less). It After that, the large particles are sent to the collecting cyclone 6 through the discharge conduit 11a and collected. Intermediate particles are exhaust conduit 1
It is discharged to the outside of the system through 2a and collected by the collection cyclone 5, and each product is collected as much as possible. In addition, small nonstandard particles are discharged to the outside of the system through the discharge conduit 13a and collected by the collection cyclone 4. The collecting cyclones 4, 5 and 6 are arranged such that the powder raw material is passed through the raw material supply pipe 16 to the classification chamber 32.
It functions as a suction decompression means for suction introduction into.

The airflow classifier according to the present invention is effectively used particularly for classifying toner or a colored resin powder for toner used in an image forming method by electrophotography. In particular, it is effective when classifying a toner containing a binder resin having a low melting point, a low softening point, and a low glass transition point. When a toner composition using such a resin is subjected to a conventional classifier, a fused substance is likely to be generated at the tip of the classification edge, and when the fused substance is generated, it tends to deviate from an appropriate classification point. Therefore, it is difficult to obtain the required particle size distribution of the powder even if the flow rate is adjusted by suction decompression, and the classification efficiency is significantly reduced. or,
A fusion product was mixed in the classified powder, and a good quality product could not be obtained. On the other hand, in the airflow classifier of the present invention, when the classification edges 17 and 18 are moved, the direction of the classification edge is aligned with the flow direction of the particle flow flying along the Coanda block 26 by the movement of the coarse powder side block 24. In addition, the discharge conduit 1 can be used as a suction pressure reducing means.
By adjusting the flow rate of the suction flow via 1a, 12a and 13a, the flight speed of the particles can be increased and the dispersion of the powder in the classification region can be further improved, so that the classification yield becomes good,
In addition, fusion to the tip of the classification edge can be prevented or suppressed, and there is an effect that highly accurate classification can be performed.

In the classifying device of the present invention, when the position of the coarse powder side block 24 is moved, a stepping motor or the like is used as the moving means, and a potentiometer or the like is used as the detecting means for detecting the edge tip position. It is more preferable to control the position of the tip of the classification edge by a control device that controls these and to further automate the flow rate adjustment, because the desired classification point can be obtained more accurately in a short time. When the raw material powder is classified using this classifier, a toner having a sharp particle size distribution can be obtained from a toner raw material having a weight average diameter of 10 μm or less, and classification can be performed more efficiently than in the past. . In particular, a toner having a sharp particle size distribution can be obtained from a toner raw material having a weight average diameter of 8 μm or less. By using this apparatus, it is possible to classify and generate toner more efficiently than ever before.

[0025]

As described above, according to the airflow type classifier of the present invention, the classification edge can be easily set at the optimum position, so that the turbulent flow of the classification airflow at the tip of the classification edge can be improved. It can be obtained from the accurate classification point according to the specific gravity of various powders and classification airflow conditions, and the toner with a sharp particle size distribution can be obtained with a high classification yield, preventing the abrasion of the equipment due to the toner component, and continuously. And stable production can be performed. Further, according to the present invention, a toner for developing an electrostatic charge image, which has a stable and high image density, has good image durability, and can give an excellent image without image defects such as fog and cleaning failure, has a low cost. Provided by. In particular, according to the present invention, it is possible to efficiently obtain a toner having a sharp particle size distribution from a toner raw material having a weight average diameter of 10 μm or less, and further, to obtain a sharp particle size from a toner raw material having a weight average diameter of 8 μm or less. It is possible to efficiently obtain a toner having a distribution.

[Brief description of drawings]

FIG. 1 is a sectional view of an airflow classifier according to an example of the present invention.

2 is a perspective view of the airflow classifier of FIG. 1. FIG.

FIG. 3 is a diagram showing an example of an entire apparatus system using the airflow classifier shown in FIG.

FIG. 4 is a partially enlarged view of a classification area portion of the airflow classifier of FIG.

FIG. 5 is a cross-sectional view of a conventional airflow classifier.

6 is a perspective view of the airflow classifier of FIG.

[Explanation of symbols]

 1: Solid particle multi-division classifier 2: Fixed amount feeder 3: Vibratory fielder 4, 5, 6: Collection cyclone 11, 12, 13: Discharge port 11a, 12a, 13a: Discharge conduit 14, 15: Inlet port 16: Raw material supply pipe 17, 18: Classification edge 17a, 18a: Classification edge axis 19: Inlet edge 19a: Inlet edge axis 20: First gas introduction adjusting means 21: Second gas introduction adjusting means 22, 23 : Side wall block 24: Side wall block on coarse powder side (Coarse powder side block) 25: Lower wall 26: Coanda block 27: Upper wall 28, 29: Static pressure gauge 30: Solid particle scattering trajectory 30a: Coarse particle scattering trajectory 30b : Scattering trajectory of medium powder particles 30c: Scattering trajectory of fine powder particles 31: Injection feeder 32: Classification chamber 32: Positioning member 60: Position adjusting means 101: Conventional solid particles Multi-division classifier 111, 112, 113: Conventional outlet 114, 115: Conventional inlet 116: Conventional raw material supply pipe 117, 118: Conventional classification edge 119: Conventional inlet 120: Conventional First gas introduction adjusting means 121: Conventional second gas introduction adjusting means 122, 123: Conventional side wall 124: Conventional coarse powder side wall block 125: Conventional lower wall 126: Conventional Coanda block 127: Conventional upper part Walls 128, 129: Conventional static pressure gauge 132: Conventional classification chamber

Claims (2)

[Claims] 1. A powdery raw material having at least a classification area formed by a Coanda block, a side wall block and a plurality of classification edges, and the powder raw material supplied from a raw material supply pipe in the classification area is at least a coarse powder group due to the Coanda effect. In an airflow classifier that classifies into a medium powder group and a fine powder group, the installation position of the side wall block on the coarse powder group side is configured to be movable so that the shape of the classification area can be changed. An airflow classifier characterized by this. 2. The installation position of the side wall block on the coarse powder side is movable in a horizontal direction or in a substantially horizontal direction.
Airflow classifier described in.