JP2003340314A - Gravity separation method for particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance separation accuracy by expanding an equal settling particle size ratio by a vibrtation field even if sufficient adjustment of a particle size is not performed beforehand, with respect to polydisperse fine particles with a particles size of 50 μm or less difficult in gravity separation heretofore. <P>SOLUTION: In a gravity separation method for particles performing the gravity separation of particles with high specific gravity and particles with low specific gravity, settling velocity difference due to the magnitude of specific gravities of particles is utilized. Vibration is applied in the settling direction of particles, and the setting delay of particles with low specific gravity is made larger than that of particles with high specific gravity corresponding to the specific gravities of particles and the frequency and amplitude of vibration, to expand the equal settling ratio being the particle size ratio of particles different in specific gravity settled at the same velocity. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various industrial fields such as mining, manufacturing processes in various industrial fields, and recycling processes, and more particularly to a method for separating specific gravity of particles in a suspension, and in particular particles utilizing a sedimentation velocity difference. The present invention relates to a method for expanding the constant velocity sedimentation ratio in the separation of specific gravity of.

[0002]

2. Description of the Related Art Devices (jigs, tables, cyclones, etc. and their improved devices) for separating two or more particles having different specific gravities by utilizing the difference in sedimentation velocity in water are used in various places in the industrial field. There is. Since the sedimentation velocity of particles in water depends on both the specific gravity of the particles and the particle size (projected cross-sectional area), particles with large specific gravity and small particle size and particles with small specific gravity and large particle size have the same speed. Some settle. The particle size ratio of particles of different specific gravity that settle at the same rate is called the constant velocity settling ratio.

In all separation devices that utilize the difference in sedimentation velocity, particles with a large specific gravity (“high specific gravity particles” or “heavy particles”) are used.
Also called. ) In the lower part and particles with a small specific gravity (also called “low specific gravity particle” or “light particle”) are collected in the upper part to achieve separation. In addition, or heavy particles are mixed in the upper part and cannot be separated accurately. When separating particles of about several mm to several cm, the particle size can be adjusted relatively easily, but it is industrially possible to adjust the particle size of particles of several 100 μm or less, especially 50 μm or less within the constant velocity sedimentation ratio. Is extremely difficult to do.

Many of the conventional specific gravity separators for fine particles are provided with a mechanism for imparting a centrifugal field to increase the sedimentation velocity (moving velocity) of the particles. However, since the centrifugal force is similarly applied to all particles, the time required for separation can be shortened, but the constant velocity sedimentation ratio cannot be changed. Therefore, in the prior art, it was impossible to perform highly accurate specific gravity separation of polydisperse (wide particle size) fine particles.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a method for separating a specific gravity by utilizing the difference in sedimentation velocity, which makes it unnecessary to reduce the particle size adjustment before the specific gravity separation or reduce the burden thereof, and to improve the separation accuracy in the specific gravity separation of fine particles. To realize a constant velocity sedimentation ratio expansion method for particles of different specific gravity that enables improvement.

[0006]

In order to solve the above-mentioned problems, the present invention provides a method for separating the specific gravity of high specific gravity particles and low specific gravity particles by utilizing the difference in sedimentation velocity depending on the specific gravity of the particles. Vibration is applied in the sedimentation direction of particles, and the sedimentation delay of low-density particles is made larger than that of high-density particles according to the specific gravity of particles, the frequency and amplitude of vibration, and the particle size ratio of different-density particles that sediment at the same speed. And a method for separating specific gravity of particles, which is characterized by expanding the constant velocity sedimentation ratio.

In order to solve the above problems, the present invention utilizes a difference in sedimentation velocity depending on the magnitude of the specific gravity of the particles, and in the method for separating the specific gravity of particles by separating the high specific gravity particles and the low specific gravity particles from each other in the sedimentation direction of the particles. Vibration is applied and the Reynolds number is set to 0.
1, the particle size ratio of different specific gravity particles that settle at the same speed by increasing the sedimentation delay of low specific gravity particles larger than high specific gravity particles according to the specific gravity of particles, frequency and amplitude of vibration. Provided is a method for separating specific gravity of particles, which is characterized by expanding a sedimentation ratio.

The different specific gravity particles are characterized in that the particle diameters are made uniform in advance within the range of the particle diameter of the expanded constant velocity sedimentation ratio.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on examples with reference to the drawings. First, the principle of the present invention will be described. When high specific gravity particles and low specific gravity particles having various particle diameters are released into water, high specific gravity particles settle quickly if they have the same particle diameter, and particles having large particle diameters if they have the same specific gravity, as shown in FIG. Settles quickly. Among these, high specific gravity particles and low specific gravity particles having different particle sizes have the same sedimentation velocity. The ratio of the particle size A of the high specific gravity particles that settle at the same speed to the particle size B of the low specific gravity particles, B / A, is called the constant velocity settling ratio.

In the specific gravity separation method utilizing the difference in sedimentation speed, in principle, low specific gravity particles are recovered in the upper part and high specific gravity particles are recovered in the lower part. Considering the dotted line in the figure as the boundary of separation, all the particles having a higher specific gravity than the particle size A are collected downward because the sedimentation speed is faster than the particles having the particle size A. All the particles smaller than B have a slower sedimentation speed than the particles of particle size B, and thus are all collected above.

However, among the high specific gravity particles, the particle a having a diameter smaller than the particle size A is recovered above together with the low specific gravity particles, and similarly, the low specific gravity particle b having a diameter larger than the particle size B. Is collected below together with the particles having a high specific gravity, resulting in a decrease in separation accuracy.

Therefore, in order to accurately separate the high specific gravity particles and the low specific gravity particles by the specific gravity separation, it is necessary to adjust the particle size of the particle group in advance within the range of particle sizes A to B. In other words, the ratio between the maximum diameter and the minimum diameter of the particle group to be subjected to the specific gravity separation must be within the constant velocity sedimentation ratio. That is, the constant velocity sedimentation ratio means the applied particle size width in the specific gravity separation.

By the way, it is generalized that the constant velocity sedimentation ratio is expressed by the following equations 1 and 2 depending on the state of the flow of water which is a fluid.

[0014]

[Equation 1]

[0015]

[Equation 2]

Considering the formulas 1 and 2, the specific gravity is 4
Particle size of 1c when water particles and particles with specific gravity of 2 are separated in water
Since the particle of m has a flow state in the Newton region, the constant velocity sedimentation ratio is 3, and the particle size may be adjusted in advance within a range of, for example, 1 to 3 cm, which can be easily performed. However, particles having a particle diameter of 20 μm are in the Stokes region, and the constant velocity sedimentation ratio is 1.73.

That is, in this case, for example, the particle size is 20 to
The particle size must be adjusted within the range of 35 μm, and it is difficult to industrially adjust the particle size within this range. Virtually 50μ
It was impossible to separate fine particles of m or less with high precision. Thus, in the specific gravity separation of fine particles, increasing the constant velocity sedimentation ratio as much as possible leads to improvement in separation accuracy.

On the other hand, for one kind of particles settling in water,
It is generally known that when water is vibrated in the vertical direction, the sedimentation velocity of particles is delayed as shown in FIG.
According to the present invention, when two kinds of particles having different specific gravities are placed in the same vibration field, particles having a large particle size receive a larger fluid resistance, and the degree of sedimentation velocity delay is larger than that of particles having a small particle size. This is a method that applies As a result, for particles with a specific gravity and small particle size (heavy particles) that settle at a constant velocity in a stationary fluid and particles with a small specific gravity and large particle size (light particles), the light particles have a lower sedimentation velocity in the oscillating fluid. The delay increases and the constant velocity settling ratio increases.

On the other hand, the flow state is classified into a Newton region (Reynolds number of 500 or more), an Allen region (Reynolds number of 2 to 500), and a Stokes region (Reynolds number of 2 or less) according to the Reynolds number. In the conventional studies, when the particles settle at the terminal velocity, only the settling delay for particles having a particle size of several mm to several cm is examined so that the fluid flow near the particles belongs to the Newton region. Further, it has been considered that the sedimentation delay hardly occurs in the sedimentation of fine particles having a small Reynolds number and belonging to the Stokes region.

However, not only in the Allen region, but when placed in an oscillating field in which the Reynolds number at the time of particle precipitation exceeds 0.1 for fine particles, strictly speaking, the Stokes A slight deviation from the equation causes a delay in settling.

For example, vibrations such that the Reynolds number is about 0.2 or more (depending on the particle size and specific gravity of the particles, for example,
A sine wave or square wave with a frequency of 500 Hz or more and an amplitude of 100 μm or more. If the frequency is doubled, almost the same vibration field can be given even if the amplitude is halved. ) To water causes a delay in sedimentation due to a slight deviation from the Stokes equation, although it is in the so-called Stokes range.

Similar to the Newton region, the delay is larger in the light particles than in the heavy particles, so that the constant velocity sedimentation ratio is expanded. The degree of expansion of the constant velocity sedimentation ratio increases as the Reynolds number of the fluid near the particles increases with increasing frequency and amplitude.

The present invention utilizes a difference in sedimentation velocity depending on the magnitude of the specific gravity of the particles, and in a method for separating the specific gravity of particles of high specific gravity and particles of low specific gravity, vibration is applied in the sedimentation direction of the particles to obtain the specific gravity of the particles. According to the frequency and amplitude of vibration, the settling delay of the low specific gravity particles is made larger than that of the heavy particles, and the constant velocity settling ratio, which is the particle size ratio of the different specific gravity particles settling at the same speed, is expanded. This is a method for separating specific gravity of particles.

In this case, vibration is applied in the particle settling direction,
Reynolds number is at least greater than 0.1. By doing so, it is possible to arrange the range of different particle diameters of the particles of different specific gravity having the constant velocity sedimentation ratio to a wide range in advance, and to target the particles having the particle diameter of the wide range for the specific gravity separation.

In short, according to the present invention, in the method for separating the specific gravity of particles, by applying vibration in the settling direction of the particles, the constant velocity settling ratio is expanded, and high specific gravity particles that enable specific gravity separation of particles are provided. As the particle size ratio of low specific gravity particles increases, it becomes possible to separate the specific gravity of fine particle regions where the flow state becomes the Stokes region, that is, to expand the target particle size region that can be selected by specific gravity in the particle specific gravity separation method. You can

(Experiment) The verification of expansion of the constant velocity sedimentation ratio was carried out by the experimental apparatus shown in FIG. In FIG. 3, the experimental device 1 includes a vibrating device 2, a glass cell 3 vibrated by the vibrating device 2, and a measurement processing device 4.

The vibration device 2 includes a vibration reducer 5 and a vibration reducer 5
The vibrating machine 6 provided above the vibrating plate 6 vibrates the water in the glass cell 3 through the vibrating plate 7 in the vertical direction. The shaker 6 is connected to the function generator 9 via the amplifier 8.

The measurement processing device 4 is equipped with a microscope 10 (using an optical microscope) for enlarging and detecting water mixed with particles contained in the glass cell 3 and taking a detection image. Camera 11 and high-speed camera controller 12
And a computer 13 for inputting an image signal from the high-speed camera 11 to measure the behavior of particles. further,
The high-speed camera controller 12 is connected to the monitor 14 and the oscilloscope 15.

In the experiment, the glass cell 3 was filled with water as indicated by the hatched portion (shown in a half cross-sectional view),
The sample particle suspension is gently charged from the particle charging unit 16 at the upper end of the. The function generator 9 generates a wave having an arbitrary frequency, amplitude, and waveform, which is amplified by an amplifier, and then the signal is input to the vibration exciter 6. The diaphragm 7 vibrates up and down in accordance with this signal, causing the water filled in the glass cell 3 to generate a vibration field.

The motion of particles settling in the vibration field of water is photographed by the high-speed camera 11 via the microscope 10, and the image pickup signal obtained by this photographed signal is used by the control computer 1.
Enter 3 to measure the sedimentation trajectory and sedimentation velocity of the particles.

(Experimental Example) FIGS. 4A and 4B show the results of the experimental example. This experimental example shows a settling trajectory when two types of glass beads having different densities and particle sizes (suspension concentration 0.1%) were put into still water and water oscillated with a sinusoidal wave having a frequency of 500 Hz and an amplitude of 100 μm. It is a thing.

In the experimental results shown in FIGS. 4A and 4B, particles having a specific gravity of 4.2 and a specific gravity of 2.6 have a constant velocity sedimentation ratio of 1.41 in the Stokes region in still water, and a specific gravity of 4.2. ,
For heavy particles having a particle size of 29.2 μm, light particles having a specific gravity of 2.6 and a particle size of 41.3 μm settle at a constant velocity.

That is, since light particles having a particle size of 41.3 μm or more settle faster than heavy particles having a particle size of 29.2 μm,
When these mixed particle groups are separated by specific gravity, they are both collected on the heavy particle side (downward) and cannot be separated in still water.

FIG. 4B shows that the light particles have a specific gravity of 2.6,
This is an experimental example using particles having a particle size of 44.7 μm. The result of this experimental example shows that the sedimentation velocity in still water is 1910 μm.
/ S, which indicates that the heavy particles cannot be separated faster than the sedimentation speed of 1640 μm / s.

When an oscillating field is applied here, the Reynolds number of the fluid in the vicinity of the particles becomes large, which deviates from the Stokes equation and delays the sedimentation velocity. At this time, the light particles having a large particle size are subjected to a larger fluid resistance, so that the degree of delay is also increased. The results of the figure show that the sedimentation velocity of heavy particles is 1420 μm / s, whereas that of light particles is 1280 μm / s.
And the reversal of the sedimentation rate has occurred. That is, it shows that light particles of 44.7 μm, which cannot be separated in still water, can be separated.

Under the experimental conditions, the light particles were 1420 μm /
The particle size of s is estimated to be about 47.3 μm, which means that the constant velocity sedimentation ratio is increased from 1.41 to 1.62.
The expansion of the constant velocity sedimentation ratio becomes more significant as the frequency of vibration is higher and the amplitude is larger, and as the difference in specific gravity between the particles to be separated is larger. Also, if you use other viscous fluid instead of water,
Although the sedimentation velocity in the stationary fluid differs depending on the viscosity, the expansion of the constant velocity sedimentation ratio due to vibration similarly occurs.

Although the embodiment of the present invention has been described above based on the examples, the present invention is not particularly limited to such examples and within the scope of the technical matters described in the claims. It goes without saying that there are various embodiments.

[0038]

According to the present invention having the above-described structure, in the conventional specific gravity separator, if a vibration field is applied in the sedimentation direction of the particles, the sedimentation of the light particles according to the specific gravity of the particles, the frequency and the amplitude of vibration. The delay becomes larger than that of heavy particles, and the constant velocity sedimentation ratio increases, so that it is possible to eliminate or reduce the burden of particle size adjustment in advance.

In particular, for polydisperse fine particles of 50 μm or less, which have been difficult to be separated by specific gravity, separation accuracy can be increased by expanding the constant velocity sedimentation ratio by a vibration field, even if sufficient particle size adjustment cannot be performed in advance. It becomes possible to improve.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the concept of constant velocity sedimentation ratio by specific gravity separation.

FIG. 2 is a diagram illustrating a concept of expansion of a constant velocity sedimentation ratio by vibrating water.

FIG. 3 is a diagram illustrating an experimental device that demonstrates the present invention.

FIG. 4 is a diagram illustrating an example of an experimental result of the present invention.

[Explanation of symbols]

1 Experimental device 2 Vibration device 4 Measurement processor 6 shaker 10 microscope 11 High-speed camera 16 Particle input section

Claims (3)

[Claims] 1. A method for separating the specific gravity of particles, in which high specific gravity particles and low specific gravity particles are subjected to specific gravity separation by utilizing the difference in sedimentation velocity depending on the magnitude of specific gravity of particles, vibration is applied in the sedimentation direction of the particles, and specific gravity and vibration of the particles are given. Particles characterized by increasing the sedimentation delay of low-density particles larger than that of high-density particles according to the frequency and amplitude of the particles, and expanding the constant velocity sedimentation ratio, which is the particle size ratio of different-density particles that sediment at the same speed. Specific gravity separation method. 2. In a method for separating specific gravity of particles by separating specific gravity of high specific gravity particles and low specific gravity particles by utilizing the difference in sedimentation velocity depending on the specific gravity of particles, vibration is applied in the sedimentation direction of the particles, and Reynolds number of 0. 1, the particle size ratio of different specific gravity particles that settle at the same speed by increasing the sedimentation delay of low specific gravity particles larger than high specific gravity particles according to the specific gravity of particles, frequency and amplitude of vibration. A method for separating specific gravity of particles, characterized by expanding the sedimentation ratio. 3. The particle size of the different-specific-gravity particles is made uniform in advance within the range of the particle size of the constant velocity sedimentation ratio.
The method for separating specific gravity of particles as described.