# US 8,540,174 B2 · Method for producing powder and fluidized bed pulverizing apparatus

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- Number: US 8,540,174 B2
- Document ID: US8540174B2
- Status: Granted
- Kind: B2
- Application number: 12/888,964
- Filed: 2010-09-23
- Published: 2011-03-31
- Granted: 2013-09-24
- Earliest claimed: 2009-09-25
- Assignees: Ricoh Company, Ltd.
- Applicants: Nobuyasu Makino
- Inventors: Nobuyasu Makino
- Web page: https://patentgrep.com/patent/US8540174B2

## CPC

- B02C 19/065: {of the opposed-jet type (B02C19/068 takes precedence)}
- B02C 23/12: with return of oversize material to crushing or disintegrating zone
- B02C 25/00: Control arrangements specially adapted for crushing or disintegrating
- B02C: CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN ({household tools and machines for pulverising foodstuffs, e.g. coffee and spice mills A47J42/00; pharmaceutical mortars A61J3/02; mechanical processing of refuse and garbage B03B9/06; dressing mould materials by grinding B22C5/04}; obtaining metallic powder by crushing, grinding or milling B22F9/04; {recovery of plastics by disintegrating B29B17/00; crushing raw materials in starch making C08B30/02; beaters for papermaking D21D1/02; crushing devices specially for transport in mines E21F13/002; slag crushing devices F23J1/00; fuel milling devices in combustion apparatus F23K1/00; household devices for crushing coal F24B15/02; ice disintegrating devices F25C5/02})

## Abstract

A method for producing powder including supplying a powder material to a fluidized bed container, jetting fluid from each of a plurality of fluid jetting nozzles provided in the fluidized bed container to collide against each other, thereby fluidizing and pulverizing the powder material in the fluidized bed container to form powder, classifying the powder using a centrifugal classification rotor provided at the upper part of the fluidized bed container and discharging the classified powder from an outlet by being guided by the centrifugal classification rotor, wherein the centrifugal classification rotor is rotated at a first rotating speed for a predetermined time from the beginning of the flow of the powder material in the fluidized bed container, and at a second rotating speed after the predetermined time has passed, and the centrifugal classification rotor is controlled so that the first rotating speed is higher than the second rotating speed.

## Claims

### Claim 1

A method for producing powder comprising:
supplying a powder material from a powder material supply inlet to a fluidized bed container;
jetting fluid from each of a plurality of fluid jetting nozzles provided in the fluidized bed container so as to collide against each other, thereby fluidizing and pulverizing the powder material in the fluidized bed container to form powder;
classifying the powder using a centrifugal classification rotor provided at the upper part of the fluidized bed container; and
discharging the classified powder from an outlet by being guided by the centrifugal classification rotor;
wherein the centrifugal classification rotor is rotated at a first rotating speed for a predetermined time from the beginning of the flow of the powder material in the fluidized bed container, and at a second rotating speed after the predetermined time has passed, and the centrifugal classification rotor is controlled so that the first rotating speed is higher than the second rotating speed.

### Claim 2 (depends on 1)

The method for producing powder according to claim 1, wherein the jetting further comprises controlling the internal pressure of the fluidized bed container to negative pressure.

### Claim 3 (depends on 1)

The method for producing powder according to claim 1, wherein the jetting further comprises controlling the temperature inside the fluidized bed container.

### Claim 4 (depends on 1)

The method for producing powder according to claim 1, wherein the jetting further comprises controlling the injection pressure of the fluid jetted from the fluid jetting nozzle.

### Claim 5 (depends on 1)

The method for producing powder according to claim 1, wherein the predetermined time from the beginning of the flow of the powder material for rotating the centrifugal classification rotor at the first rotating speed is controlled.

### Claim 6 (depends on 5)

The method for producing powder according to claim 5, wherein the predetermined time is 10 seconds to 170 seconds.

### Claim 7 (depends on 1)

The method for producing powder according to claim 1, wherein the supplying, the jetting, the classifying, and the discharging are performed by automatic control.

### Claim 8 (depends on 1)

The method for producing powder according to claim 1, wherein the powder is a toner.

### Claim 9 (depends on 1)

The method for producing powder according to claim 1, wherein the fluid is one selected from the group consisting of air, nitrogen, carbon dioxide, helium and argon or a mixture of two or more of these gases.

### Claim 10 (depends on 1)

The method for producing powder according to claim 1, wherein the first rotating speed of the centrifugal classification rotor is faster than the second rotating speed by 10 m/s to 30 m/s in terms of a circumferential speed of a rotor of the centrifugal classification rotor.