JPS61153163A - Electrostatically classifying apparatus of powdery granular body - Google Patents

Abstract

PURPOSE:To classify the powder granular bodies efficiently without the clogging by making a pair of opposed sieves both electrodes, providing the electrode plates to the backs of the electrodes and spraying the electrically-conductive particles between both the electrodes. CONSTITUTION:A pair of sieves 11, 12 provided with the meshes wherein the powdery and granular bodies having the prescribed particle size and below are passed therethrough are opposed in the up-and-down direction and made to both electrodes. The electrode plates 15, 16 are arranged in the backs of the sieves 11, 12 of both the electrodes via the insulators 13, 14. The electrically-conductive particles 17 having the particle size larger than the prescribed particle size are sprayed between a pair of electrodes 11-15, 12-16 respectively. The sieve 11 and the electrode plate 16 are grounded and the sieve 12 and the electrode plate 15 are connected with an anode side of a high-voltage DC power source 22. When the powdery granular bodies 18 are introduced from a channel 21, these are sent between the sieves 11, 12 by means of the air current of a suction fan 26 and classified. In this case, since the sieves are always beaten by the electrically-conductive particles, the efficient classification is performed without clogging.

Description

Detailed Description of the Invention (Technical Field to which the Invention Pertains) The present invention is directed to charging powder and granules made of conductive particles with different particle sizes and passing them through a sieve using Coulomb force to obtain powder and granules of a predetermined particle size. The present invention relates to an electrostatic classifier.

(Prior art and its problems) This type of device is used, for example, to classify the particle size of abrasive particles made of silicon carbide to produce a grindstone with a desired roughness. Are known. This device uses a metal screen 1, which is formed in a flat plate shape and placed horizontally and has a mesh size that allows particles of a particle size below a predetermined size to pass therethrough, as an upper electrode, and is vertically opposed to this. A roller 4 driven by a belt by a motor 3 is supported between a flat lower electrode 2 placed in parallel with a roller 4 and a storage container 5 for storing powder and granules remaining after particles of a predetermined size are collected. An endless dielectric belt 8 passed between the lower electrode 2 and the lower electrode 2 is run close to the lower electrode 2, and the conductive powder supplied from the sample box 7 onto the dielectric belt 8 is applied to both the electrodes. When passing between 1.2,
First, this granular material is charged with the same polarity as the lower electrode 2, and this charged granular material is caused to fly toward the upper electrode 1 having the opposite polarity by Coulomb force, and the flying speed and air suction fan 9 at this time are The purpose is to use the airflow sucked in the direction of the arrow to pass through the mesh of the sieve that constitutes the upper electrode. The powder that collided with the sieve and could not pass through the mesh is now charged with the polarity of the upper electrode and attracted towards the belt, where it is charged with the opposite polarity again, and the above process is repeated. It is accommodated in the bag filter IO. Therefore, on the dielectric belt that has passed between the electrodes 1 and 2, particles with a predetermined particle size or less have been removed, and large powder particles and mixed insulating particles remain. be accommodated.

However, in such devices, when the predetermined particle size to be classified is made finer, the thickness of the metal wires that make up the mesh cannot be made very thin due to both mechanical strength and manufacturing difficulty, so the total area of the sieve is reduced. The percentage of the total area of the mesh, that is, the aperture ratio, decreases, which not only reduces the efficiency of the classification work, but also causes clogging, and when the predetermined particle size to be classified is a few microns, it is no longer possible to use this method. It becomes impossible to classify.

Therefore, as a device for classifying such fine powder, there is a sieve shaker using ultrasonic waves. Although this sieve shaker is not particularly shown here, the powder to be classified is placed in a sieve with a mesh of a predetermined size, immersed in a container filled with water, and the sieve is passed through the sieve. Ultrasonic vibration is applied to the container in a fixed state, and while the powder to be classified is vibrated through water, powder with a predetermined particle size or less is taken out.

However, since the powder extracted by this method is wet, if it is used in a dry state,
An extra drying step is added to the classification work, which increases the cost to obtain the desired powder or granular material.

(Objective of the Invention) An object of the present invention is to provide an electrostatic classifier that uses a dry classification method and can efficiently classify fine powder without clogging.

(Summary of the Invention) The present invention is an electrostatic classification device that charges powder and granules made of conductive particles of different particle sizes and passes them through a sieve using Coulomb force to obtain powder and granules of a predetermined particle size. A pair of sieves placed and facing each other in the vertical direction are used as both electrodes, and an electrode plate is arranged behind each of the two electrodes to further constitute a pair of electrodes, and each of the pair of electrodes is The above object is achieved by dispersing conductive particles having a particle size larger than the predetermined particle size between the sieves and introducing the classified powder between the pair of sieves. It is something to do. That is, the second
As shown in the figure, a pair of sieves 11 and 12 each having a mesh that allows powder particles of a predetermined particle size or less to pass through are vertically opposed to form both electrodes, and a high-voltage DC power supply with the cathode side grounded. Connect the anode side of 22 to sieve 12,
1 is grounded. Behind each of the sieves 11.12 constituting both electrodes, an electrode plate 15.16 is arranged with an insulator 13.14 in between, and each pair of electrodes 11-1
5.12-16 are constructed, and conductive particles having a particle size larger than the predetermined particle size are sprinkled between each pair of electrodes. The electrode plate 15 is connected to an anode having a polarity opposite to that of the other electrode 11, and the electrode plate 16 is also connected to the other electrode 1.
2, the large conductive particles are connected to the ground potential of opposite polarity to sieve 11. ．． electrodes 11.15 and 12.16 without passing through the mesh of 12.
The sieves 11 and 12 are hit while reciprocating between the sieves 11 and 12.

On the other hand, the powder particles smaller than the mesh of the sieve 11.12 in the powder particles introduced from the outside between the sieves 11.12 are classified according to the same classification principle as in the conventional example shown in FIG. , the electrode space A that passes through the sieve mesh and is behind it.
, enters B. In this electrode space, there is an air flow heading towards the bag filter (not shown), so powder particles with a predetermined particle size are accommodated in the bag filter, and coarse particles with a particle size larger than the mesh of the sieve are As such, it is discharged from this classification device.

By the way, the sieves 11 and 12 are beaten by large conductive particles that are spread between them and the electrodes 15 and 16 behind them, so even when the particles to be classified are fine, the sieves are The fine powder that accumulates around the mesh and causes clogging is constantly knocked off by the sieve 12, and the fine powder that accumulates on the lower sieve 11 easily flies toward the upper sieve 12, and the fine powder that accumulates around the mesh of the sieve causes clogging. The size always remains the original size. Therefore, the initial classification efficiency can always be maintained without the classification efficiency decreasing over time.

(Embodiment of the Invention) ' Fig. 1 shows an embodiment of an electrostatic classifier based on the present invention. As can be seen from the figure, the space formed between the pair of sieves 11 and 12, which are placed horizontally and opposed to each other with a small interval in the vertical direction, is the space formed between the channels 21 into which the granular material 18 to be classified is introduced. Insulating plate 211 forming the side wall? The sides are closed by. Channel 21 is this insulating plate 211? The inlet is formed by the upper and lower insulating plates 21α, and the insulating plate 21C and the upper and lower insulating plates 2
The discharge port is formed by 1A.

Electrode plates 15.16 are arranged behind each of the pair of opposing sieves 11.12, and the sieve 11 and the electrode plate 15.16 are arranged behind each other.
Spaces A and B between the sieve 12 and the electrode plate 16 (
(see Figure 2) are 13,210 and 14.21, respectively.
', and each electrode space A, B is a duct 24
It is connected to the bag filter room 25 via α and 24A. A suction fan z6 is attached to the bub filter chamber 25, and the suction fan z6 passes from the powder introduction port of the channel 21 through the space formed by the pair of sieves 11 and 12 and the electrode spaces A and B behind each sieve. Bag filter room 25
Creates an air flow towards.

The sieve 11 and electrode plate 16 of the electrostatic classifier thus configured are grounded, and the sieve 12 and electrode plate 15 are connected to the anode side of the high voltage DC power supply z2.

When the granular material 18 is introduced from the inlet of the channel 21 together with the air flow 23 in this state, the granular material 18 is passed through the pair of sieves 11 and 12 by the air flow generated by the suction 7 amp 26.
Powder particles having a predetermined particle size or less enter the electrode spaces A and B, and are further sent into the bag filter chamber 25 by the air flow. In addition, the large conductive particles scattered in the electrode spaces A and B are constantly filtered through the sieve 11.1 during the operation of the classification device.
2, the mesh size of the sieve always maintains its original size, and the initial classification efficiency can be maintained even over time.

After the powder grains with a predetermined particle size or less are classified in this way,
Powder grains having a larger particle size are discharged from the outlet of the channel 21 as shown in 19 in the figure, and are stored in a storage container (not shown).

Also, in the embodiment shown in FIG.

When the pitch of the opposing meshes of the lower pair of sieves is shifted by half a pitch as shown in Fig. 2, particles of a predetermined particle size or less that fly toward the other sieve due to Coulomb force are Because the distance between the sieves is small and a high voltage is applied to this pair of sieves, the particles fly perpendicular to the sieve surface and can easily pass through the mesh of the other sieve. , the amount of powder that can be classified within a certain period of time increases.

(Effects of the Invention) As described above, according to the present invention, (1) since a pair of sieves placed horizontally and facing each other in the vertical direction are used as both electrodes, the granular material to be classified is It can be classified in both downward directions and has high classification efficiency.

(2) An electrode space is formed behind each of a pair of sieves, large metal particles are scattered in this electrode space, and a high DC voltage is applied between the two electrodes that make up this space. Since the sieve is constantly tapped during operation of the classification device, there is no clogging even when the particles to be classified are fine, and the sieve mesh size always maintains its original size.
The initial classification efficiency is always maintained without decreasing the classification efficiency over time.

(3) Since the electrostatic classifier of the present invention is a dry type, there is no need for a drying process for powder and granules unlike in the case of a wet shaker that uses ultrasonic waves, and it can separate fine powder with a small particle size into coarse particles with a large particle size. It can be obtained at the same cost as grain.

In addition to the effects of The additional effect is that the amount of granules increases and the classification efficiency can be improved.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of the configuration of an electrostatic classifier based on the present invention, Fig. 2 is a classification principle diagram explaining the improvement in classification efficiency according to the present invention, and Fig. 3 is a conventional electrostatic classifier. FIG. 1: Sieve, 2: Electrode, 12° sieve, 15.16: Electrode plate, 17: Conductive particles, 1a
: Powder, 21: Channel. Expression Shrine 11←Figure 1

Claims (1)

[Scope of Claims] 1) An electrostatic classifier that obtains powder or granular material of a predetermined particle size by charging powder or granular material made of conductive particles with different particle sizes and passing it through a sieve using Coulomb force, which A pair of sieves placed on the screen and facing each other in the vertical direction are used as both electrodes, and an electrode plate is arranged behind each electrode of the two electrodes to further form a pair of electrodes. A granular material characterized in that it is configured such that conductive particles having a particle size larger than the predetermined particle size are spread between the two sieves, and the classified granular material is introduced between the pair of sieves. electrostatic classifier. 2) In the electrostatic classification device according to claim 1, the pitch of the meshes of one sieve and the pitch of the meshes of the other sieve of a pair of sieves forming both electrodes are shifted by half a pitch from each other. An electrostatic classification device for powder and granular materials characterized by being arranged as follows.