JPH09192532A - Powder classifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a classifier for powder which performs the classification which can control the particle size distribution of recovered powder correctly within a desired range as well as solid-liquid separation which separates liquid from slurry in which powder and liquid is mixed and which is made turbid. SOLUTION: A tank 10 for receiving slurry in which powder and liquid is mixed and which is made turbid, the first cyclone 20 which removes rough powder which is made to communicate with it and to be connected with it from the tank 10 through a slurry pump 12, and the second cyclone 40 which removes fine powder which is made to communicate with it and to be connected with it are used as components. At least either of the first and second cyclones 20, 40 is made to arrange cyclone main bodies 22, 26, 44, 46,...54 in parallel, and valves 23, 24, 44a, 44c... are installed in pipelines on the inlet side and on the outlet side of each cyclone main body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder classifier capable of controlling a particle size distribution of powder particles to be separated and recovered within a desired range while separating a liquid from a slurry in which powder particles and a liquid are turbid. In particular, the present invention provides an apparatus suitable for wet classification of metal powder from a slurry in a water atomizing method.

[0002]

2. Description of the Related Art The metal powder used in powder metallurgy has a uniform alloy composition and powder particle size, and is manufactured at low cost.
Generally, a gas or liquid (water) atomizing method is used. In particular, in order to obtain relatively fine metal powder with an average particle size of 50 μm or less, which has been in increasing demand in recent years, high pressure (40-100 M
pa) Water atomization method is adopted.

A few μm to a few atomized with such high-pressure water
The metal powder of 10 μm becomes a slurry together with water at the time of atomization, is sent and stored in a large aquarium tank by a pump, and is solid-liquid separated by spontaneous sedimentation, and the recovered metal powder is subjected to dehydration and drying steps. The product powder in the required particle size distribution range was collected by classification using a multi-stage mesh or air flow method. When the above-mentioned metal powder and water are separated by the natural sedimentation method, the finer the powder, the longer the processing time is, and a considerably large water tank is required for batch processing, and the classification is performed after the separation step. In order to increase the number of steps and to obtain a relatively fine product powder, it is necessary to perform classification by an air stream after classification with a mesh body, resulting in a problem that the number of steps is large.

In order to improve the above-mentioned prior art, the applicant has previously proposed and filed an invention of a solid-liquid separation method and a device therefor capable of continuously performing solid-liquid separation and powder classification in the same step ( Japanese Patent Application No. 7-209057). According to the present invention, a first hydrocyclone for removing coarse powder and a second hydrocyclone for removing fine powder are connected in communication, and a slurry of water atomized metal powder and water is continuously fed to them by a slurry pump. That is the gist. By such an invention, it was possible to reduce the man-hours, improve the productivity, and reduce the equipment space.However, since the range of the coarse powder and the fine powder removed by each hydrocyclone becomes constant, it can be variously varied. In order to obtain a product powder having a wide particle size distribution, particularly a relatively fine metal powder in a particle size distribution for each lot,
And / or replace the second hydrocyclone,
It was necessary to replace the parts in each of these cyclones, or to perform dehydration and drying through both cyclones and then separately perform classification with a mesh body.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a further improvement of the previously proposed invention, which enables solid-liquid separation and powder classification to be continuously processed in the same step, and has a particle size distribution of powder particles within a desired range. The present invention relates to a powder classifying device that can be accurately controlled inside, and particularly to provide a device suitable for wet classifying metal powder from a slurry in a water atomizing method.

[0006]

[MEANS FOR SOLVING THE PROBLEMS]
In order to achieve the object, the powder classifying device of the present invention comprises a tank containing a slurry in which powder particles and a liquid are turbid, and a first tank which is connected to the tank through a slurry pump.
And a second hydrocyclone communicating with and connected to the cyclone, wherein at least one of the first and second hydrocyclones has a plurality of cyclone bodies arranged in parallel and A valve is provided in the pipeline of the cyclone body on the inlet side and the outlet side of the slurry.

[0007] As described above, one of the first and second hydrocyclones has a plurality of cyclone bodies arranged in parallel, and the number of the used cyclones is controlled by opening and closing the valve to remove coarse particles. And the particle size range of the fine powder,
The principle described in detail later can be performed accurately, and it becomes possible to perform such classification and solid-liquid separation at the same time.

In addition, an intermediate tank and a slurry pump may be interposed in the conduits of the first hydrocyclone and the second hydrocyclone, or the plurality of cyclone main bodies arranged in parallel may be The cyclone bodies are arranged radially at the same height as each other with the branch cylinders in the pipeline as the center, and further, the plurality of cyclone main bodies arranged in parallel have a volume and a pipeline on the inlet side and discharge side of the slurry. It is also possible to make the inner diameters of the two different. Further, the valves provided in the slurry inlet side and discharge side pipelines of each cyclone body are butterfly valves, ball valves,
Any of a solenoid valve, a sluice valve, a cock, a control valve capable of adjusting the opening degree, or a needle valve can be used.
In addition, a final product powder can be obtained by connecting a liquid removing device to which powder particles underflowing from the cyclone are fed to the second hydrocyclone and a drying device downstream thereof. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the powder classifying device of the present invention will be specifically described with reference to the drawings. FIG. 1 is an explanatory diagram showing the overall structure of a powder classifying apparatus according to an embodiment of the present invention and the flow of a slurry or the like. The molten metal M adjusted to have a desired alloy composition in an induction furnace or the like and melted is a tundish 1 The atomized water is poured into the inside, is finely poured from the pouring nozzle 2 on the bottom surface thereof, and is atomized by the high-pressure water W which is sprayed downward from the ring-shaped atomizer 4 in a conical shape while falling. Slurry S that becomes cloudy is stored in a tank 10 called a chamber. The slurry S in the tank 10 is pressure-fed to the first hydrocyclone 20 by the slurry pump 12 via the pipe line 14. The first hydrocyclone 20 has two cyclone bodies 22, 26 arranged in parallel with each other.
In the pipe lines 16 and 16 on the inlet side of the slurry S of 22 and 26,
The valves 23 and 27 for opening and closing the pipes are also removed from the lower outlets 25 and 29 of the cyclone bodies 22 and 26 by the coarse particles BP as an underflow, and the remaining slurry S is removed from the body 2
Overflow is discharged from above 2 and 26, and valves 24 and 28 are provided in the pipelines 30 and 30 on that side, respectively.

Pipe line 3 from the two cyclone bodies 22, 26
Numerals 0 and 30 form a single conduit 32 and communicate with the inside of the intermediate tank 34, and the slurry S discharged from the first hydrocyclone 20 is once stored in the intermediate tank 34. Further, the slurry S is transferred from the intermediate tank 34 to the pipeline by the slurry pump 36.
It is pumped into the chamber 38 and fed to the second hydrocyclone 40 side. Incidentally, these intermediate tank 34 and slurry pump 36
Is not an essential component, and can be omitted if the pressure of the slurry pump 12 can sufficiently feed the slurry S to the second hydrocyclone 40 side.

The slurry S pressure-fed through the pipe 38 is fed into the cylindrical branch cylinder 42 (see FIG. 2) from its upper surface 42a, and the branch pipe 43 radially extending from the side wall 42b of the branch cylinder 42. , 45, ..., 53, which are relatively small cyclone bodies 44, 46, which constitute the second hydrocyclone 40 provided at the respective tips.
…, Sent in 54. These cyclone bodies 44,46,
54 are arranged radially around the branch cylinder 42 and are annularly arranged at substantially the same height. The branch pipes 43, 45, which communicate with these cyclone main bodies 44, 46, ..., 54.
, 53 are provided with valves 44a, 46a, ..., 54a. In each cyclone body 44, 46, ..., 54, the fine powder SP is removed by overflow from the upper discharge side together with water, while the product powder having a desired particle size distribution to be a product is underflowed and the lower outlet 44b, Recovered from 46b, ..., 54b. Furthermore, in the discharge side pipe line 55 where the fine powder SP and the like overflow from the respective cyclone main bodies 44, 46, ..., 54,
Valves 44c, 46c, ..., 54c are provided respectively.

Here, the operation of the hydrocyclone 20, 40 will be described. As shown in the vertical sectional view of FIG.
For example, the cyclone main body 22 is a cylindrical hollow body having a conical lower part, and a horizontal wall 22d having an inner cylinder 22c vertically at the center is installed between an inlet 22a and an outlet 22e of the slurry S, and a lower outlet is provided at the lower end. A hole 22b communicating with 25 is formed. When the inflow speed is high, a large centrifugal force acts on the powder particles P in the slurry S flowing in from the inlet 22a, and the powder particles P hit the inner wall surface of the cyclone body 22 and easily fall downward, causing underflow, and conversely the inflow speed is slow. As a result, the centrifugal force acting on the powder particles P also becomes small and overflows to the outlet 22e side. Therefore, the inflow rate of the slurry particles S to be fed is made constant and the number of cyclone main bodies to be used is adjusted by opening and closing the front and rear valves to adjust the inflow rate of the powder particles P fed into each cyclone main body. You can control. The present invention relates to the first hydrocyclone 20.
Then, in the second hydrocyclone 40, the particle size of the coarse powder BP to be removed by underflow according to the above principle is
The particle size of the fine powder SP to be removed by overflow is controlled to ensure that a product powder having a desired particle size distribution is obtained.

An experiment in which the number of cyclone bodies used in the second hydrocyclone 40 is adjusted will be described. The average particle size of the metal base powder after removing the coarse powder BP having an average particle size of 35 μm in the first hydrocyclone 20 was 20 μm. Slurry S containing such mother powder
A second hydrocyclone 4 with an inflow rate of 500 liters per minute
0, adjust the opening and closing of the valves 44a, 44c, 46a, 46c, ... to underflow and recover the average particle size of the product powder and the fine powder SP that is removed by overflow. The average particle size was measured. Table 1 shows the results.

[0014]

[Table 1]

FIG. 4 (A) shows Experiment 1 in which the mother powder shown by the broken line has a relatively large and large amount of fine powder SP removed, and the particle size distribution shown by the solid line (the one-dot chain line shows the average In the experiment 4 shown in FIG. 7B, only a small amount of small fine particles SP were removed from the mother powder (broken line), so the particle size distribution of the product powder ( The solid line) and the average grain size also moved to the fine grain size side. From this experiment, it is understood that when the number of cyclones used is increased by opening / closing the valve, the underflow is decreased and the overflow is increased, and conversely, when the number is decreased, the underflow is increased and the overflow is decreased. Of course, the same applies not only to the second hydrocyclone 40 but also to the first hydrocyclone 20. Therefore, it is most desirable in terms of device configuration to arrange both cyclone bodies in parallel as shown in FIG.

FIG. 5 shows another form of the hydrocyclone according to the present invention. In the hydrocyclone 20 and 40 of the form described above, the cyclone main bodies 22 and 2 having the same volume are formed.
6,44,46, ..., 54 are arranged in parallel, and pipe lines 16,43,4 with the same inner diameter
Although the slurry S was fed by 5, ..., 53, this form is one in which cyclone bodies 57 and 58 in which different sizes of volume and corresponding inner diameter pipes are connected are arranged in parallel, and the inlet side By opening and closing the valves 57a, 58a provided in the pipeline 56, it is possible to use either or both of them, and mainly when the powder particles to be classified are known in advance. You can In addition, the pipeline 59 on the overflow side
The reason why the valves 57b and 58b are also provided is to prevent the overflowed slurry S and the like from flowing into the unused cyclone main body when only one cyclone main body is used. Hydro cyclone 2
The same applies to 0 and 40. Therefore, the opening and closing of the valve is operated in the same way in the pipe lines before and after the same cyclone body. The opening / closing operation of the valve may be performed manually, but various control means such as a controller or a microcomputer may be used to systematically control the group of valves of the entire apparatus or to perform group management / group control. .

In the first hydrocyclone 20, the coarse particles BP removed as underflow from the cyclone bodies 22 and 26 are recovered in a recovery container (not shown). The metal powder having a desired particle size contained in (1) is reclassified and used as a product powder, or is melted again and used for the atomization. In addition, the fine powder SP that overflows from the second hydrocyclone 40 and is removed together with water is separately collected and discharged. Further, the excessive slurry S is stored in the cone 42c below the branch cylinder 42 of FIG. 3 described above, and the operation valve 42d is opened to be circulated to the pipe 38 for reuse.

Product powders underflowing from the respective cyclone bodies 44, 46, ..., 54 of the second hydrocyclone 40 are collected in a hopper 66 as shown in FIG. 6 and contained in a dehydrator 68 which also serves as a recovery container. After being dehydrated and dehydrated, it is charged into the hydro hopper 70 on the downstream side, and is dried while passing through a rotary kiln-type drying device 72 which is continuous with the hydro hopper 70 to be a final product powder.

When a plurality of cyclone main bodies are arranged in parallel, they are divided into groups according to the type of powder particles to be classified, and the number of cyclone main bodies used in each group is increased or decreased. It is also possible to reduce the cleaning work inside each cyclone body. In addition, the valve described in each of the above-mentioned embodiments,
Adjustment of butterfly valve, ball valve, solenoid valve, sluice valve, cock, or opening depending on conditions such as feed pressure, properties of powder particles contained, path of pipe used, pipe inner diameter, etc. Any suitable control valve or needle valve is selected and used. In particular, when using a control valve that can adjust the degree of opening and a needle valve, without completely closing the valve body,
Depending on the particle size distribution of the desired product powder, together with the control of the number of cyclones used, the opening degree of each valve element can also be used in a narrowed state in the middle of opening and closing. The removal range can be controlled. In addition,
If the pipes for feeding the slurry are provided with a difference in length, the pressure loss in each pipe is made different, and the slurry is fed to a plurality of cyclone bodies arranged in parallel with each other, the above classification is also performed. Can contribute to the effect.

Further, the powder particles in the slurry to be treated are not limited to the above-mentioned water-atomized metal powder, but various particles such as fine sand in muddy water, synthetic resin powder in various turbid liquids, and ceramic powder are applied. be able to. Further, the liquid forming the slurry is not limited to the above-mentioned water, and various liquids such as acidic, alkaline, organic or inorganic chemical treatment liquid and industrial waste liquid can be applied. And the industrial field to which the present invention is applied along with these is not limited to the powder metallurgy field, but can be applied to various fields such as chemistry that uses solid-liquid separation and powder classification in combination, food, construction, environment, etc. it can.

[0021]

According to the powder classifying apparatus of the present invention described above, at least one of the first and second hydrocyclones has a plurality of cyclone main bodies arranged in parallel, and the number of valves to be used is equal to that of the valve. By controlling the opening / closing operation, the particle size ranges of the coarse powder and the fine powder to be removed can be accurately performed, and the product powder having a desired particle size distribution can be reliably obtained. Moreover, since it is possible to perform such classification and solid-liquid separation at the same time, it is possible to contribute to reduction of processing time / man-hours, cost, and improvement of productivity.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a powder classification device according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a branch cylinder in FIG.

FIG. 3 is a vertical sectional view of a main body of a hydrocyclone used in the present invention.

FIG. 4 is a diagram showing a particle size distribution of classified powder particles in an experiment conducted using the powder classification device of the present invention.

FIG. 5 is a schematic perspective view showing another form of the hydrocyclone used in the present invention.

FIG. 6 is a schematic configuration diagram showing a final treatment step of the powder classification device according to the embodiment of the present invention.

[Explanation of symbols]

 10 tank 12,36 slurry pump 20 (22,26) first hydrocyclone 34 intermediate tank 40 (44,46,48,50,52,54) second hydrocyclone 23,24,27,28,44a, 44c, 46a, 46c, ..., 54a, 54c Valve 42 Branch cylinder 68 Draining device 72 Drying device

Claims (6)

[Claims] 1. A tank (10) containing a slurry in which powder particles and a liquid are turbid, and a first hydrocyclone (20) connected to the tank (10) through a slurry pump (12). And a second hydrocyclone (40) connected in communication with the first hydrocyclone (20), wherein at least one of the first and second hydrocyclones (20, 40) is a plurality of cyclones. Body (22,26,4
4,46, ...) are arranged in parallel, and valves (23,2,2) are installed in the slurry inlet side and discharge side pipelines of each cyclone body.
4,44a, 44c, ...) are provided. 2. The intermediate tank (34) and the slurry pump (36) are interposed in a pipe line between the first hydrocyclone (20) and the second hydrocyclone (40). 1
The powder classifier according to. 3. The plurality of cyclone main bodies arranged in parallel at a substantially same height as each other, a branch pipe in a pipe line.
The powder classification device according to claim 1, wherein the powder classification device is arranged radially around the (42). 4. The powder classifying apparatus according to claim 1, wherein the plurality of cyclone main bodies arranged in parallel have different main body volumes and inner diameters of slurry inlet side and discharge side conduits. . 5. The valve (23, 24, 44a, 44c, ...) Is one of a butterfly valve, a ball valve, a solenoid valve, a sluice valve, a cock, a control valve with adjustable opening, and a needle valve. Claim 1
The powder classifier according to any one of claims 1 to 4. 6. The second hydrocyclone (40) comprises:
A cyclone (40) is connected to a dewatering device (68) to which powder particles underflowed are fed, and a drying device (72) is connected to the downstream side of the dewatering device (68). 1
The powder classification device according to any one of claims 1 to 5.