JP2560511B2 - Superconducting magnetic separator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a magnetic separation device used for removing iron compounds in white porcelain clay, or for removing magnetic substances in iron mill wastewater, and in particular, a superconducting magnet is used. The present invention relates to a magnetic separation device.

[Conventional technology]

Magnetic separators have long been used for iron ore beneficiation, but in the late 1960s high gradient magnetic separation (HGMS: Hig
h Gradient Megnetic Separetion) has been developed and has come to be used industrially for the purification of magnetic raw materials such as white clay and for the selection of other magnetic particles.

As is well known, the principle of the magnetic separation device is to separate magnetic particles by the force that magnetic particles having magnetic susceptibility x and volume V are placed when placed in a magnetic field H.
Is F = VxHgrad H (1), and this force is proportional to the magnetic field strength H and the magnetic field gradient grand H. A large value cannot be obtained for the magnetic field gradient grad H just by using the magnet as it is. In high gradient magnetic separation (HGMS), a local high gradient magnetic field generated around a thin ferromagnetic wire placed in the magnetic field is generated. We are using. Furthermore, in order to enhance the separation ability, it has been used to use a superconducting magnet capable of generating a high magnetic field (for example, Advances in Cryogenic En
gineering volume 33 page 53-60; 1988, Plenum Pres
s, New York).

FIG. 5 is a cross-sectional view of a conventional high gradient magnetic separation device using a superconducting magnet. A superconducting coil 2 is housed in a vacuum heat insulating container and cooled by liquid helium. This coil is a cylindrical coil and generates a magnetic field H. Reference numeral 1 denotes a thin wire made of magnetic stainless steel, for example, a filter made of a wire having a diameter of several tens of μm and arranged in a magnetic field H to generate a locally high gradient magnetic field around the thin wire. The magnetic flux generated in superconducting coil 2 is filter 1 → pole piece 3b
→ Return yoke 4 → Pole piece 3a → Pass through the magnetic circuit of filter 1. The pole pieces 3a, 3b and the return yoke 4 are made of an iron material and have a sufficient cross-sectional area for passing the magnetic flux.

As an operating procedure, for example, a slurry of ocarin containing magnetic particles flows in as a fluid to be treated 5 from a lower part of the magnetic separation device via a valve V1 and via a flow hole 6a provided in a pole piece 3a. Go into Filter 1. The magnetic particles contained in the fluid to be treated 5 are trapped by the locally high gradient magnetic field around the magnetic wire rod that constitutes the filter 1. The fluid to be processed 5 from which magnetic particles have been removed is the filter 1
Of the fluid 7 from which the magnetic particles have been removed from the valve V2 through the flow hole 6b in the ball piece 3b and the magnetic separation device.
Is taken out as. In the above-mentioned magnetic particle capturing cycle, the valves are V1: open, V2: open, V3: closed, and V4: closed. When the fluid to be processed is circulated for a long time, magnetic particles are accumulated in the filter 1 and its trapping ability is deteriorated, and therefore the cleaning cycle is started. First, the superconducting coil 2 is demagnetized, and the valves are V1: closed, V2: closed, V3:
Open, V4: Operated to open. Cleaning fluid 8, for example water, is a valve
V3 is supplied from above to the magnetic separation device from above, and the fluid containing a large amount of magnetic particles is passed through the valve from the lower part of the magnetic separation device while washing away the magnetic particles trapped in the filter 1.
Is taken out as.

[Problems to be Solved by the Invention]

In the above-mentioned magnetic separation device, iron pole pieces 3a and 3b and a return yoke 4 are provided as a magnetic circuit.
Therefore, the magnetic flux generated by the superconducting coil 2 can be effectively used, and there is almost no leakage magnetic field to the surroundings. However, the amount of iron in this magnetic circuit is enormous.
For example, in a general magnetic separation device in which the diameter of the filter 1 is about 2 m, the weight of iron becomes 150 to 200 tons. As a result, in addition to the iron material cost, the cost of assembling and transporting heavy objects, and foundation work at the installation site is high. When the amount of iron is reduced, the leakage magnetic field to the surroundings becomes large. Extremely speaking, it is possible to construct a magnetic separation device with only superconducting coils without using iron at all, but in this case,
A large installation area is required to avoid the influence of the stray magnetic field on the surroundings.

On the other hand, a coil type having a small leakage magnetic field is disclosed in Japanese Patent Laid-Open No. 51-0062.
It is known from Japanese Patent Publication No. 40, and is also used in a superconducting magnet of a magnetic resonance imaging apparatus and is called an active shield system. This coil type is composed of a cylindrical main coil and a cylindrical shield coil placed coaxially with the main coil, and the absolute values of the magnetic dipole moments of these coils are equal and their polarities are reversed. The superconducting magnet using this coil type has a small leakage magnetic field, but the magnetic field created by the shield coil partially cancels the magnetic field created by the main coil, so it is necessary to increase the ampere-turns of the main coil, and the shield coil is also costly. It takes. Superconducting magnets are currently
It is very expensive, and if this coil type superconducting magnet is applied to the magnetic separation device as it is, the cost will increase significantly.

An object of the present invention is to solve the above-mentioned problems and to provide a superconducting magnetic separation device which does not use an iron material as a magnetic circuit, has a small leakage magnetic field, and has a moderate cost of the superconducting coil. is there.

[Means for solving the problem]

In order to solve the above-mentioned problems, a superconducting magnet of the present invention and a filter composed of a ferromagnetic wire placed in a magnetic field generated by this magnet are provided, and a fluid to be treated containing magnetic particles is provided with this filter. In a superconducting type magnetic separation device in which the magnetic particles are attracted to a filter and removed from the fluid to be treated by a local high gradient magnetic field generated around the wire when passing, the superconducting magnet has a cylindrical inner superconducting The filter is composed of a coil and an outer superconducting coil which is coaxial with the coil and has a reverse polarity, and the filter is placed inside the inner superconducting coil and in an intermediate part between the outer superconducting coil and the inner superconducting coil. The superconducting magnet comprises an outer filter, and the superconducting magnet has a magnetic dipole moment of the inner superconducting coil and an absolute value of a dipole moment of the outer superconducting coil which are substantially equal and opposite to each other. And gender, so as to distribute the fluid to be treated in the antagonist of the inner filter and the outer filter.

[Action]

In the present invention, a cylindrical inner superconducting coil and a cylindrical outer superconducting coil that generates a magnetic field of a reverse magnetic pole coaxial with this are provided, and their magnetic dipole moments are substantially equal,
Also, since the polarities are opposite, the magnetic fields for the surroundings cancel each other out, and the leakage magnetic field becomes extremely low. Of course, it is not necessary to use iron material in the magnetic circuit, and the huge amount of iron in the magnetic circuit can be reduced. In addition, in the inside of the inner superconducting coil and in the middle of the outer superconducting coil and the inner superconducting coil,
Since a filter for trapping magnetic particles is provided and a fluid to be processed is circulated in the opposite direction, the magnetic field generated by the superconducting coil can be effectively utilized, and the cost of the superconducting coil with respect to the ability of the separation device can be appropriately suppressed.

〔Example〕

FIG. 1 is a sectional view of an embodiment of the superconducting magnetic separator of the present invention. 15 is a cylindrical inner superconducting coil,
Reference numeral 16 denotes a cylindrical outer superconducting coil that is coaxial with this and generates a magnetic field of opposite polarity. The superconducting magnet is composed of both coils. Both of these coils are inside vacuum insulation container 13
And it is housed in the outer vacuum insulation container 14 and cooled with liquid helium. The cylindrical inner filter 11 is the inner superconducting coil 15
Inside, the cylindrical outer filter 12 is disposed in the intermediate portion between the outer superconducting coil 16 and the inner superconducting coil 15. Then, the inner filter 11 is inside a container composed of the inner vacuum heat insulating container 13 and the end plate 17, and the outer filter 12 is outside vacuum heat insulating container 14.
And the inner vacuum heat insulating container 13 and the end plate 18 are contained. As described above, these filters are made of a thin wire made of magnetic stainless steel, for example, a wire having a diameter of several tens of μm and made like cotton. Pipes for the treated fluid 5 and the cleaning fluid 8 are attached to the upper and lower cottons of the end plates 17 and 18, respectively.

Inner superconducting coil 15 magnetic dipole moment NI ・ A
[However, NI is ampere-turn, A is coil diameter D and A
= (Π / 4) · D ² ] and the magnetic dipole moment NI · A of the outer superconducting coil 16 have almost the same absolute value and opposite polarities. In this way, the leakage magnetic field to the surroundings is rapidly attenuated by the fifth power of the distance. FIG. 3 shows the magnetic field distribution of this superconducting magnet, the vertical axis is the magnetic field H, the horizontal axis is the distance r from the center of the superconducting coil, and 11, 15, 12, and 16 are the inner filter 11 and the inner superconducting coil 15, respectively. The positional relationship between the outer filter 12 and the outer superconducting coil 16 is shown. A high magnetic field is applied to the inner filter 11 and the outer filter 16, for example, 2T shown by the solid line 23.
(Tesla) is applied and the outer superconducting coil
Magnetic fields outside 16 are very small due to the above-mentioned principle. The ampere-turn NI of the inner superconducting coil is about twice that of the outer superconducting coil. The inner superconducting coil alone generates a magnetic field of about 4T indicated by a chain line 21, and the outer superconducting coil alone generates a magnetic field of about 2T indicated by a broken line 22. As a result, the magnetic field applied to the inner filter is about 2T and the magnetic field applied to the outer filter is about 2T as described above. Therefore, both the inner and outer filters have almost the same ability to trap magnetic particles. The fluid 5 to be processed is circulated in parallel to both filters.

The operating procedure is similar to that of the device shown in FIG.

FIG. 2 shows a sectional view of a different embodiment of the superconducting magnetic separator of the present invention. In this embodiment, the inner superconducting coil 15 has a smaller diameter and more ampere turns than the embodiment shown in FIG. At the same time, the magnetic dipole moment NI · A of the inner superconducting coil 15 and the magnetic dipole moment NI · A of the outer superconducting coil are almost equal, and
It is set to the opposite polarity. FIG. 4 shows the magnetic field distribution of this superconducting magnet, and H, r, 11, 15, 12, and 16 in the figure are the same as those in FIG. The inner superconducting coil alone, for example, generates a magnetic field of about 6T indicated by a chain line 21, and the outer superconducting coil alone generates a magnetic field of about 2T indicated by a broken line 22. As a result, the magnetic field applied to the inner filter as shown by the solid line 22 is about
At 4T, the magnetic field on the outer filter is about 2T. Since the magnetic dipole moments MI · A of the inner and outer superconducting coils are almost equal and have opposite polarities, the leakage magnetic field outside the outer superconducting coils is very small, as in the embodiment of FIG. .

As shown in FIG. 2, the fluid to be treated 5 is first passed through the outer filter 12 having a low magnetic field, and then passed through the connecting pipe 31 to the inner filter 11. The outer filter with a low magnetic field traps particles with a relatively high magnetic susceptibility x, and the inner filter with a high magnetic field traps particles with a relatively low magnetic susceptibility. At the time of cleaning, the cleaning wastewater 9a for the inner filter and the cleaning wastewater 9b for the outer filter are separately taken out from the discharge pipes 32 and 33, so that the magnetic particles in the fluid to be treated can be separated and collected into two kinds of substances.

〔The invention's effect〕

According to the present invention, an inner superconducting coil and an outer superconducting coil coaxial with the inner superconducting coil and having opposite polarities are provided, and the magnetic dipole moments of both coils are made equal in absolute value and the polarities thereof are reversed. Needless to say, the leakage magnetic field to the surroundings could be made extremely low without using it, but the filter for trapping the magnetic particles is not only inside the inner superconducting coil but also in the middle part between the outer superconducting coil and the inner superconducting coil. As compared with the conventional superconducting type magnetic separation device shown in FIG. 5, the volume of the filter is approximately tripled and the processing capacity is increased by the same outer diameter. Further, due to the increase in the processing capacity, the cost of the superconducting coil per processing capacity can be appropriately suppressed.

Furthermore, by making the magnetic fields of the inner filter and the outer filter different in magnitude, the fluid to be processed is first passed through a filter with a low magnetic field and then through a filter with a high magnetic field to capture the magnetic field. Since the particles can be separated and collected into two kinds of substances, the collected magnetic particles can be used more effectively.

[Brief description of drawings]

1 is a sectional view of a superconducting magnetic separator according to one embodiment of the present invention, FIG. 2 is a sectional view of a superconducting magnetic separator according to another embodiment of the present invention, and FIG. 3 is a superconducting type of FIG. Explanatory drawing showing magnetic field distribution of superconducting magnet of magnetic separation device, FIG.
FIG. 5 is an explanatory view showing a magnetic field distribution of a superconducting magnet of the superconducting magnetic separator shown in FIG. 5, and FIG. 5 is a sectional view of a conventional superconducting magnetic separator. 5: Fluid to be treated, 11: Inner filter, 12: Outer filter, 1
5: Inner superconducting coil (superconducting magnet), 16: Outer superconducting coil (superconducting magnet).

Claims (1)

(57) [Claims] 1. A filter comprising a superconducting magnet and a ferromagnetic wire placed in a magnetic field generated by the magnet, and when a fluid to be treated containing magnetic particles passes through the filter, the circumference of the wire is increased. The local high gradient magnetic field generated in
In a superconducting type magnetic separation device that removes the magnetic particles from a fluid to be treated by sucking them into a filter, the superconducting magnet comprises a cylindrical inner superconducting coil and a cylindrical outer superconducting coil coaxial with the inner superconducting coil. , The filter is composed of an inner filter arranged inside the inner superconducting coil and an outer filter arranged between the outer superconducting coil and the inner superconducting coil, and the superconducting magnet is a magnetic dipole moment of the inner superconducting coil. A superconducting magnetic separation device, characterized in that the outer superconducting coils have substantially equal absolute dipole moments and opposite polarities, and a fluid to be processed is circulated between the inner filter and the outer filter.