JPH0763572B2 - High magnetic field gradient magnetic separation method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high magnetic field gradient magnetic separation method and apparatus for the purpose of removing and recovering magnetic particles contained in a fluid.

[0002]

2. Description of the Related Art By filling a ferromagnetic fiber in a magnetic field, a large magnetic field gradient is formed on the surface of the fiber,
The method of attracting and capturing magnetic particles in a fluid has been known in principle for a long time. (For example, commentary / Transactions o
n Magnetics, vol MAG-10, No2, June, 1974, pp. 223 et seq.) Various systems have been disclosed for devices embodying the above principles. There are electromagnets, solenoids, permanent magnets, etc. as a method of applying a magnetic field, and stainless fibers, spherical bodies, or recently amorphous fibers are also used as a ferromagnetic matrix. As a method of filling the fiber matrix, a method of arranging multiple layers of a porous sheet woven in a mesh shape at right angles to a magnetic field in order to improve recovery efficiency has been implemented. In addition, a method of packing a matrix as it is without knitting it has been conventionally used. This method is simple because it does not require the work of knitting in a mesh shape, but since the matrix is oriented in a random direction, it also includes a part that does not contribute to the recovery of magnetic particles, so it has both advantages and disadvantages such as a low recovery rate. There is.

High field gradient magnetic separation requires a backwash step. The backwash process is performed to restore the state in which the ability of the matrix to remove and recover the magnetic particles deteriorates. Generally, the magnetic field is released or the matrix is taken out of the magnetic field to form a matrix. This is to wash off the adsorbed magnetic particles. In other words, the matrix is clogged with adsorbed particles due to long-term operation, resulting in a decrease in removal efficiency and an increase in fluid resistance.
The role of backwash is to restore this to the initial state. In order to carry out backwashing, it is necessary to temporarily stop the line, which causes a decrease in the efficiency of equipment equipped with a magnetic separator and a decrease in work efficiency.

[0004]

SUMMARY OF THE INVENTION In order to reduce the frequency of backwashing steps in high magnetic field gradient magnetic separation, the present invention is directed to
An object of the present invention is to provide a method and an apparatus for keeping the removal and recovery ability of magnetic particles for a long time and suppressing an increase in pressure loss due to clogging of a matrix to a minimum.

[0005]

The present invention uses a permanent magnet as a magnetic field source and uses a high magnetic field gradient generated by a ferromagnetic matrix filled in a magnetic field to detect a detected magnetic field. Large change in pressure of processing fluid
Depending on the size, the position of the permanent magnet should be aligned with the flow path of the fluid to be treated.
A magnetic separation method and a device embodying the same, characterized by changing from downstream to upstream . Here, the setting method of the position of the permanent magnet is arranged at the downstream side of the container filled with the matrix at the start of the operation of the magnetic separation device, and when the increase in the predetermined fluid pressure is detected, the position is moved in the upstream direction according to the increase amount. It is what makes me.

The method and apparatus of the present invention will be described with reference to FIG.
This will be described more specifically. FIG. 1 assumes that the fluid to be processed is flowing in the direction of the arrow of the flow path 9, that is, from the bottom to the top. 3 is a permanent magnet, the length of which is preferably approximately the same as or slightly longer than the length of the container 5 filled with the ferromagnetic matrix 7. The passage 11 of the magnet 3 is arranged so as to surround the container 5 filled with the ferromagnetic matrix 7, and the length thereof is shorter than the sum of the lengths of the magnet 3 and the matrix container 5, and is shown in FIG. As a matrix container 5
It is arranged relatively upward with respect to. Further, the lower end of the passage 11 is adjusted to have substantially the same height as the lower end of the matrix container 5. Here, the length of the container means the length of the portion substantially filled with the matrix, and the length of the passage 11 means the length of the space in which the permanent magnet can move. Magnet 3,
The reason for determining the length and relative arrangement of the passage 11 and the container 5 as described above is that at least a part of the lower end of the magnet needs to overlap with the upper part of the matrix when the magnet is located at the upper end.

Next, an example of a method of operating the apparatus of the present invention will be described. The permanent magnet 3 is arranged at the upper end of the magnet passage 11 when the matrix 7 has just been replaced. Reference numeral 12 is a differential pressure gauge for measuring the difference between the pressure of the fluid to be treated on the inlet side and the outlet side of the matrix container. When the pressure increase is within a predetermined range with respect to the steady-state pressure difference P _o , the permanent magnet 3 holds the initial position. When the pressure increase due to the adsorbed particles reaches a predetermined value ΔP with the passage of time, the magnet 3 is moved to, for example , a mode.
It is moved down by L by the drive mechanism 13 using the target . In this state, when the operating time further elapses and the pressure further increases by ΔP, the magnet 3 is further moved downward by L. By repeating this process, finally magnet 3
Reaches the lower end of the passage 11. At this time, the entire ferromagnetic matrix 7 is soiled by the adsorbed particles on average, and therefore backwashing is performed. Regarding the specific setting of the differential pressure ΔP and the moving distance L, the type of matrix, the fiber diameter of the fiber, the filling rate,
Since it depends on many factors such as the filling length, the type of fluid to be treated, and the pressure, it is determined in advance according to the actual use environment and the required performance (for example, removal efficiency). What is important is to set the magnet so that it reaches the lower end of the passage before the maximum allowable pressure difference ΔP _m is reached.

Needless to say, the above operation is only an example, and it is possible to continuously move the magnet in response to a pressure change. Also, combinations with known methods for the structure of the device are included in the scope of the present invention. For example, as a means for shortening the line stop time due to backwashing, the method of dividing a container containing a matrix disclosed in Japanese Utility Model Laid-Open No. 56-121415 into a plurality of cartridges can be used together.

Next, the sectional shapes of the container 5 and the permanent magnet 3 will be described. The container 5 is preferably cylindrical and the permanent magnet 3 is preferably arcuate in cross section. A pair of permanent magnets magnetized in the radial direction are arranged so that the N pole and the S pole face each other as shown in FIG. When the magnets are arcuate, compared to the case where the flat magnets are opposed to each other, the leakage magnetic flux at the ends is small, so that a uniform and strong magnetic field is formed.
It goes without saying that the cross-sectional shape of the passage 11 which also serves as the container of the permanent magnet 3 depends on that of the permanent magnet. If the magnet has an arc shape, the cross section of the passage 11 will inevitably have an arc shape. However, the above-mentioned magnet cross-sectional shape is recommended from the viewpoint of improving the removal efficiency of magnetic particles, and if the removal efficiency is not so important, a flat magnet can be used.
The types of permanent magnets that can be used in the present invention are ferrite type,
Rare earth type, Alnico type, Heusler alloy, etc. Further, a powdered magnet obtained by hardening the magnet with plastic or the like can also be used.

The configuration of the peripheral portion of the device of the present invention will be described. The container 5 filled with the ferromagnetic matrix is detachably provided in the flow path 9 for the fluid to be processed through the expansion joint 1. This is because the container 5 is removed from the channel 9 when the matrix is washed or replaced. It should be noted that the container 5 is made of a non-magnetic material, and has a required strength and does not cause deformation or cracks such as corrosion or reaction due to the fluid to be treated and softening due to heat in some cases. For example, acrylic, vinyl chloride, aluminum, brass, austenitic stainless steel, etc. can be used. 6 is a perforated plate provided in the container 5, and 8 is a fluid passage hole. The ferromagnetic matrix is
It is appropriately selected depending on the type of fluid, the type and particle size of particles to be captured. If the fluid to be treated is highly corrosive, it is necessary to use a matrix material that has corrosion resistance accordingly. In addition, a material with a strong elasticity (a material with a strong spring property) is advantageous because it is unlikely to cause performance deterioration. The most suitable for this purpose are amorphous alloy fibers, which have acid resistance, alkali resistance,
It is possible to select components suitable for each environment such as salt resistance. Another feature is that it has a strong elasticity. Filling rate is 1 vol for removal and recovery of ferromagnetic particles
% Is sufficient to prevent clogging, and the frequency of backwashing can be further reduced, so it is recommended to use amorphous alloy fibers.

A feature of the present invention is to shift the relative position of the permanent magnet, which is the magnetic field generating source, with respect to the ferromagnetic matrix. In the conventional high magnetic field gradient magnetic separation method, most of the magnetic particles are adsorbed only on the fluid-entry side matrix to block the channel, and the whole matrix must be backwashed before the remaining matrix functions. It was On the other hand, as an improved type, a cartridge system has been proposed in which the container filled with the matrix is divided into a plurality of cartridges, but the frequency of cartridge replacement work that requires manual labor has not been reduced. The present invention brings about the effect of remarkably reducing the replacement frequency of the matrix container and the backwashing frequency as compared with the conventional method by automatically moving the magnet and utilizing the entire matrix.

[0012]

EXAMPLE A high magnetic field gradient magnetic separator according to the present invention was installed in the middle of an apparatus for circulating coolant in a small cold rolling mill. The main part of this magnetic separation device is a cylindrical non-magnetic stainless steel container with an inner diameter of 3 cm and a length of 20 cm filled with 1% by volume of amorphous alloy fiber as a matrix, and a length of 22 cm, an inner diameter of 5 cm and a thickness of 1 cm. Of arc-shaped magnets and a magnet passage having a length of 38 cm.
However, the magnet is a rare earth bond magnet, the matrix container is connected to a steel pipe with an inner diameter of 2 cm for coolant circulation through an expansion joint, and the bypass that connects the steel pipe near the expansion joint is filled with fluid. A differential pressure gauge is provided for detecting the differential pressure on the side output side.

The lower end position of the magnet at the start of operation of the cold rolling mill is arranged at a position 1/4 from the downstream side of the matrix container (A in FIG. 1), and the threshold value of the differential pressure which is the starting point of the magnet movement is 1 cm.
Set to Aq. When carbon steel was rolled while flowing a coolant with an average flow rate of 20 l / min, the actual operating time (cumulative operating time) until the allowable differential pressure of 4 cmAq of the high magnetic field gradient magnetic separator of the present invention was reached was 56 hours. Met.

On the other hand, in the conventional high magnetic field gradient magnetic separation device having no magnet moving mechanism, which was used for comparison, the actual operating time until reaching the allowable differential pressure of 4 cmAq was 21 hours. However, the magnet position is the most upstream position of the passage (D in Fig. 1).
Then, the comparison was made under the same conditions except for the magnet moving mechanism.

[0015]

As described above, it is apparent that the high magnetic field gradient magnetic separation method having the magnet moving mechanism of the present invention has a longer operation time until the matrix exchange, as compared with the conventional method. As described above, by adopting the magnetic separation method of the present invention, the frequency of backwash was remarkably reduced, and the work efficiency was significantly improved. Further, the magnetic separation apparatus of the present invention was able to effectively carry out this magnetic separation method.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a high magnetic field gradient magnetic separation method and apparatus of the present invention, in which (a) is a side view showing an overall image;
(B) is a cross-sectional plan view of the main part.

[Explanation of symbols]

 1 Expansion Joint 2 Seal Packing 3 Permanent Magnet 5 Matrix Container 6 Eye Plate 7 Ferromagnetic Matrix 8 Fluid Passage Hole 9 Flow Path 11 Magnet Passage 12 Differential Pressure Gauge 13 Magnet Drive Mechanism

Claims (2)

[Claims] 1. A magnetic separation method using a permanent magnet as a magnetic field source and utilizing a high magnetic field gradient generated by a ferromagnetic matrix filled in a magnetic field, the detected object to be processed.
Depending on the magnitude of the pressure change of the fluid, the high magnetic field gradient magnetic separation wherein the can variables toward the downstream to the upstream along the position of the permanent magnet in the flow path of the fluid to be treated. 2. Ferromagnetism provided in the flow path of the fluid to be processed
A container filled with a body matrix, surrounding the container
Of the permanent magnets arranged in such a way that pressure changes in the fluid to be processed can be detected.
A magnetic field is generated according to the output mechanism and the detected pressure change.
Mechanism for setting the moving distance of the permanent magnet of the source, and permanent
Characterized by having a mechanism to move the magnet along the flow path
High magnetic field gradient magnetic separator.