JPS61136430A - Preparation of granulated powder - Google Patents

Abstract

PURPOSE:To enable the granulation of powders having various shapes, by extruding a slurry adjusted to proper viscosity, prepared by mixing, calcining and crushing stock materials, from fine orifices of the nozzle of a pressure container under pressure before cutting, dehydrating and drying the extrudate. CONSTITUTION:Stock materials compounded in a predetermined composition within a stock material hopper 1 are calcined and crushed to be dispersed in a proper solvent to prepare a slurry which is, in turn, thrown in a pressure container 3. Pressure is applied to the pressure container 3 by a compressor 2 to control the extrusion speed of the slurry from a nozzle 4 with a cutter. By changing the shape of minute orifice parts provided to the nozzle, the shape of a granule can be variously changed. In cutting the extruded slurry by a cutter, the cutting length of the extruded slurry is changed to regulate the length of the granule. The cut granulated powder is dried on a heated drying belt 5 and carried by a bucket conveyor 7 and supplied from a granulated powder hopper 8 by a constant amount.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing powder, and in particular to an improvement in the granulation process.

[Prior art 1] As one of the methods for producing powder and granules, granules with a desired diameter and length are created using a wooden extruder with many small holes in a method that has been known for a long time, and then the granules are There is a method of manufacturing pills, such as traditional Chinese medicine, in which a large number of pills are sandwiched between two plates and the plates are moved in parallel and relative to each other to make granules.

However, this method cannot be applied as a modern industrial-scale manufacturing method due to processing capacity.

On the other hand, as a method for manufacturing ferrite carriers used in electrophotographic developers, a method of granulation using a spray dryer has been widely put into practical use. however,
When using a spray dryer, only spherical granulated powder or granulated powder with a combination of three or more spherical particles can be produced, and there are problems in terms of shape reproducibility and yield. there were.

[Problems to be Solved by the Present Invention] Therefore, it has been desired to realize a granulation method that can suitably produce powders that require a change in shape with good reproducibility. The present invention was made to meet such needs, and it is an object of the present invention to provide a novel manufacturing method that can granulate powders of various shapes without using a spray dryer.

[Means for Solving the Problems] In order to achieve the above object, the present invention mixes raw material powders of a desired composition, calcinates and grinds them, and then adds a solvent to form a slurry with appropriate viscosity. The slurry is placed in a pressure vessel having a nozzle with a plurality of minute holes, and by applying pressure, the slurry is extruded from the minute holes of the nozzle, and the extruded slurry is cut into appropriate lengths. It is characterized by being dehydrated, dried and granulated.

The present invention has the advantage that powders of various shapes can be easily granulated by changing the shape of the microholes formed in the nozzle and the cutting length of the extruded slurry. In addition, in the present invention, the shape and size of the granulated powder are related to the precision of the microholes of the extrusion die, that is, the nozzle.
It needs to be manufactured with sufficient precision. In addition, extrusion can be easily and precisely extruded by controlling the pressure inside the popper using a pressure sensor and adjusting the speed. Grain length is measured and managed by extrusion speed and, for example, an optical sensor to ensure accurate cutting, and a cutter such as a wire cutter is used to perform highly accurate cutting. Dehydration and drying can easily be carried out continuously by using a moisture-absorbing seatbelt, for example.

Furthermore, obtaining spherical granulated powder can be easily achieved by applying horizontal vibration during dehydration and drying.

[Operation] FIG. 1 is a schematic process diagram for explaining the method of the present invention. In the figure, raw materials that have been weighed and blended to a predetermined composition are mixed in a raw material hopper 1, calcined and pulverized, then an appropriate solvent is added to prepare a slurry, and a pressure vessel 3
Input into. Pressure is supplied to the pressure vessel 3 by a compressor 2, thereby adjusting the extrusion speed of the slurry from the nozzle 4. By changing the shape of the minute hole provided in the nozzle 4, various shapes can be made, and the length can be adjusted by changing the interval when cutting the slurry extruded by the cutter.

The cut granulated powder is dried on a drying belt 5 heated by a heater 6, transported by a packet conveyor 7, fed at a constant rate from a granulation hopper 8, sintered, and then classified to have a desired shape. It becomes the final product.

[Example] A 3a-Zn-Ni-based irregular carrier was manufactured using the method of the present invention.

In the manufacturing process, raw materials were weighed and mixed, then calcined and ground to obtain calcined powder. Mix this calcined product with a binder such as PVA,
The material was placed in a hopper equipped with an extrusion/extrusion mold, extruded under pressure, cut into desired lengths, and dehydrated and dried on a moisture absorbing belt. By sintering the obtained granulated powder in a continuous sintering furnace, it was possible to obtain irregularly shaped ferrite carriers in the form of fine particles of any shape from 20 to 200 μm.

[Effects of the Invention] As detailed above, granulated powder is produced by a wet extrusion method without using a spray dryer. According to the present invention, it is possible to manufacture granules of any shape, and the yield is also improved, making it possible to stably produce products industrially.

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram for explaining the method of the present invention. Indication of procedural amendment case 1982 Patent application No. 257862 Name of the invention Relationship to the case of person amending the manufacturing method of granulated powder Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5
0g>Norio Kawano, Representative of Hitachi Metals, Ltd.

Claims (1)

[Claims] After mixing, calcining, and pulverizing the raw materials, the slurry is made into a slurry with appropriate viscosity, and the slurry is put into a pressure vessel and pressurized to extrude it through the micro holes of the nozzle provided in the pressure vessel, and the extruded slurry is A method for producing granulated powder, which comprises cutting the powder into desired lengths, dehydrating and drying the powder, and granulating the powder.