JPH03229603A - Superconducting type magnetic separator - Google Patents

Abstract

PURPOSE:To make a leakage magnetic field smeller without using iron in a magnetic circuit by the arrangement such that the absolute value of a magnetic dipole moment of an inner superconducting coil and that of an outer superconducting coil are made approximately equal and both the coils have reversed polarities. CONSTITUTION:An inner superconducting coil 15 and an outer superconducting coil 16 are placed in an inner vacuum insulated vessel 13 and an outer vacuum insulated vessel 14 respectively so that they are cooled by means of liquid helium. An inner filter 11 is placed in a vessel made up of the vessel 13 and end plates 17, while an outer filter 12 in a vessel made up of the vessel 14, the vessel 13 and end plates 18. These filters are constructed of fine magnetic stainless steel wires. The absolute value of the magnetic dipole moment of the coil 15 and that of the coil 16 are made approximately equal and the coils 15, 16 have reversed polarities. As a result, the magnetic fields of both coils act in the reverse directions, so that a leakage magnetic field is made smaller. And amounts of iron required of a magnetic circuit can be greatly reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a magnetic separation device used for removing iron compounds from white china clay or magnetic substances from wastewater from steel works, and is particularly applicable to superconducting magnets. Regarding the magnetic separation device used.

[Conventional technology]

Magnetic separation equipment has been used for iron ore beneficiation for a long time, but high gradient magnetic separation (HGM) was introduced in the late 1960s.
S: High Gradient Magnetic
5eparation) was developed and came to be used industrially for refining porcelain raw materials such as white china clay and for sorting other magnetic particles.

As is well known, the principle of a magnetic separation device is to separate magnetic particles by the force they receive when magnetic particles with a magnetic susceptibility of X1 and a volume of V are placed in a magnetic field H, where F is F. -V x Hgrad H・------------
(1), and this force is the magnetic field strength H1, the magnetic field gradient gr
ad is proportional to H. A large value cannot be obtained for the magnetic field gradient grad H by simply using a magnet as is, but in high gradient magnetic bone till (HGMS), a local high gradient magnetic field is created around a thin ferromagnetic wire placed in a magnetic field. is used. Additionally, superconducting magnets capable of generating high magnetic fields are being used to improve separation capabilities (e.g., Advances in Cryogeni
c Engineering volume 33 p.
age 53-60; 1988+P1enumPr
ess, New York) FIG. 5 is a cross-sectional view of a conventional high gradient magnetic separation device using superconducting magnets. 2 is a superconducting coil that is housed in a vacuum insulation container and cooled with liquid helium. This coil is a cylindrical coil that generates a magnetic field H. Reference numeral 1 denotes a filter made of a thin magnetic stainless steel wire, for example, several tens of wires, arranged in a magnetic field H, and generates a local high gradient magnetic field around the thin wire. The magnetic flux generated in the superconducting coil 2 is transferred from the filter 1 to the pole piece 3b→
It passes through the magnetic circuit of return yoke 4 → pole piece 3a → filter 1. The pole pieces 3a, 3b and the return cork 4 are made of iron and have a cross-sectional area sufficient to pass the magnetic flux.

As the operating procedure, for example, a slurry containing magnetic particles with a force #υ on flows as the fluid 5 to be treated from the lower part of the magnetic separation device via the valve v1, and flows into the flow hole 6a provided in the pole piece 3a. It enters the filter via . Magnetic particles contained in the fluid to be treated 5 are captured by a local high gradient magnetic field around the magnetic wire constituting the filter. Fluid 5 to be treated from which magnetic particles have been removed
exits the filter and enters the flow hole 6 in the pole piece 3b.
It exits the magnetic separator via b and is taken out from valve v2 as fluid 7 from which magnetic particles have been removed. In the magnetic particle capture cycle described above, the valves are vl: open, v2: open, v3:
Closed.

v4: Closed. If the fluid to be treated is passed through the filter for a long period of time, magnetic particles will accumulate on the filter and the ability to capture them will decrease, so a cleaning cycle will be started. First, the superconducting coil 2 is demagnetized, and the valves are operated as vl: closed, v2: closed, v3: open, and v4: open. A cleaning fluid 8, for example water, is supplied from above to the magnetic separator via valve v3 and contains a large amount of magnetic particles through the valve from the bottom of the magnetic separator while washing away the magnetic particles that have been trapped in the filter 1. It is taken out as fluid 9.

[Problem to be solved by the invention]

In the magnetic separation device described above, iron pole pieces 3a, 3b and a return yoke 4 are provided as magnetic circuits. Therefore, the magnetic flux generated by the superconducting coil 2 can be used effectively, and there is almost no magnetic field leaking to the surroundings. However, the amount of iron in this magnetic circuit is enormous. For example, in a typical magnetic separation device in which the filter 1 has a diameter of about 2 m, the weight of iron is 150 to 200 tons. As a result, in addition to the cost of iron materials, the cost of assembling and transporting heavy objects and the foundation work at the installation site are high. If you try to reduce the amount of iron, the leakage magnetic field to the surrounding area will increase. In the extreme, it is possible to construct a magnetic separation device using only superconducting coils without using iron at all, but in this case, a vast installation area is required to avoid the influence of leakage magnetic fields to the surroundings.

On the other hand, a coil type with a small leakage magnetic field is also used in the superconducting magnet of the Japanese Patent Application Laid-Open No. 1983-1973 disconnection device, and is called an active shield type. This coil type consists of a cylindrical main coil and a cylindrical shield coil placed coaxially with and outside the main coil, with magnetic dipole moments of both coils having equal absolute values and opposite polarities. Superconducting magnets using this coil type have 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.
Shielded coils are also costly.

Superconducting magnets are currently very expensive, and if this coil-type superconducting magnet were applied to a magnetic separation device as is, the cost would increase significantly.

An object of the present invention is to solve the above-mentioned problems without using iron materials as a magnetic circuit, and with a small leakage magnetic field.
Moreover, it is an object of the present invention to provide a superconducting groove type magnetic separation device whose superconducting coil cost is moderate.

[Means to solve the problem]

In order to solve the above-mentioned problems, a superconducting magnet of the present invention and a filter made of a ferromagnetic wire placed in the magnetic field generated by the magnet are provided, and a fluid to be treated containing magnetic particles is
In a superconducting magnetic separation device in which the magnetic particles are attracted to the filter and removed from the fluid to be treated by a local high gradient magnetic field generated around the wire when passing through the filter, the superconducting magnet is cylindrical. It consists of an inner superconducting coil and a cylindrical outer superconducting coil coaxial with the inner superconducting coil and having opposite polarity. and an outer filter,
In the superconducting magnet, the magnetic dipole moment of the inner superconducting coil and the dipole moment of the outer superconducting coil are approximately equal in absolute value and have opposite polarities, so that the fluid to be treated flows through the inner filter and the outer filter.

[Effect]

The present invention includes a cylindrical inner superconducting coil and a cylindrical outer superconducting coil that is coaxial with the cylindrical superconducting coil and generates a magnetic field with opposite magnetic poles.The magnetic dipole moments of the coils are made almost equal and have opposite polarities, so that The magnetic fields of both coils cancel each other out, resulting in a very low leakage magnetic field. Of course, there is no need to use iron material in the magnetic circuit, and the enormous amount of iron in the magnetic circuit can be reduced. In addition, the inside of the inner superconducting coil,
A filter for capturing magnetic particles is provided in the middle between the outer superconducting coil and the inner superconducting coil, and the fluid to be treated is allowed to flow through this partner, so the magnetic field generated by the superconducting coil can be effectively utilized, allowing separation. The cost of superconducting coils relative to the capabilities of the device can be kept reasonably low.

〔Example〕

FIG. 1 shows a sectional view of an embodiment of a superconducting magnetic separation device of the present invention. 15 is a cylindrical inner superconducting coil;
16 is a cylindrical outer superconducting coil that is coaxial with this and generates a magnetic field of opposite polarity, and a superconducting magnet is composed of these two coils. Both coils are housed in an inner vacuum insulation container 13 and an outer vacuum insulation container 14, respectively, and are cooled with liquid helium.

A cylindrical inner filter 11 is arranged inside the inner superconducting coil 15 , and a cylindrical outer filter 12 is arranged at an intermediate portion between the outer superconducting coil 16 and the inner superconducting coil 15 .

The inner filter 11 is housed in a container made up of an inner vacuum insulated container 13 and an end plate 17, and the outer filter 12 is housed in a container made up of an outer vacuum insulated container 14, an inner vacuum insulated container 13, and an end plate 18. These filters, as already mentioned, are made of thin wires of magnetic stainless steel, e.g.
It is made from dozens of wire rods shaped like cotton. End plates 17 and 18
Pipes for the fluid to be treated 5 and the cleaning fluid 8 are attached to the upper and lower parts of the pipe.

Magnetic dipole moment Nl・A of the inner superconducting coil 15
[However, NI is an ampere turn, A is a coil diameter of D, and A-(π/4)・D”) and the magnetic dipole moment of the outer superconducting coil 16) are almost equal in absolute value to NiA and opposite in polarity. In this way, the leakage magnetic field to the surroundings will rapidly attenuate as the fifth power of the distance. Figure 3 shows the magnetic field distribution of this superconducting magnet, with the vertical axis representing the magnetic field H and the horizontal axis representing the center of the superconducting coil. The distance ll1r from 11.15.12.
16 are inner filters 11 . Inner superconducting coil 1
5. Outer filter 12. The positional relationship of the outer superconducting coils 16 is shown. Inner filter 11 and outer filter 16
A high magnetic field, for example, 2T (tesla) shown in %123, is applied to This is approximately twice the ampere turns Nl of the superconducting coil. The inner superconducting coil alone generates a magnetic field of about 4 T as indicated by the flW line 21,
The outer superconducting coil alone generates a magnetic field of approximately 2 T, indicated by dashed line 22. As a result, as mentioned above, the magnetic field applied to the inner filter is about 2 T, and the magnetic field applied to the outer filter is also about 2 T. Therefore, both the inner and outer filters have approximately equal magnetic particle trapping capabilities. The fluid to be treated 5 is passed through both filters in parallel.

The operating procedure is similar to the apparatus shown in FIG. 5 already described.

FIG. 2 shows a cross-sectional view of a different embodiment of the superconducting magnetic separation device 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 N1-A of the outer superconducting coil are almost equal,
And, the polarity is determined to be reversed. Figure 4 shows the magnetic field distribution of this superconducting magnet, and H, r, 11.15.12.
16 is the same as that in FIG. The inner superconducting coil, for example, alone generates a magnetic field of approximately 6 T, indicated by ill[m21, and the outer superconducting coil alone generates a magnetic field of approximately 2 T, indicated by dashed line 22. As a result, as shown by the solid line 22, the magnetic field applied to the inner filter is about 4, and the magnetic field applied to the outer filter is about 2. Since the magnetic dipole moments A of the inner and outer superconducting coils are almost equal and have opposite polarities, the leakage magnetic field outside the outer superconducting coil is suppressed to a very low level, which is the same as in the embodiment shown in Fig. 1. .

As shown in FIG. 2, the fluid 5 to be treated is first passed through the outer filter 12 with a low magnetic field, and then passed through the connecting pipe 31 and passed through the inner filter 11. Comparison of magnetic susceptibility Large particles are captured, followed by particles with a relatively low magnetic susceptibility in the inner filter with a high magnetic field. When cleaning, the cleaning waste water 9a of the inner filter
and the cleaning waste water 9b of the outer filter are discharged separately from the discharge pipes 32 and 3.
3, the magnetic particles in the fluid to be treated can be separated into two types of substances and recovered.

〔Effect of the invention〕

According to the present invention, an inner superconducting coil and an outer superconducting coil coaxial with the same and having opposite polarities are provided, and by making the absolute values of the magnetic dipole moments of both coils equal and having opposite polarities,
Of course, we were able to reduce the leakage magnetic field to the surroundings very low without using a large amount of magnetic circuit made of iron material, but we also installed a filter that captures magnetic particles not only inside the inner superconducting coil, but also between the outer superconducting coil and the inner superconducting coil. Since it is also provided in the middle between the superconducting coil and the superconducting coil, the volume of the filter increases by about three times with the same outer diameter compared to the conventional superconducting thick type magnetic separator shown in Fig. 5. The processing capacity has also increased accordingly. In addition, due to the increase in processing capacity, the cost of superconducting coils per processing capacity can now be moderately reduced.

Furthermore, the magnitude of the magnetic fields of the inner filter and the outer filter may be made different so that the fluid to be treated first passes through the filter with a low magnetic field and then passes through the filter with a high magnetic field, thereby increasing the magnetic field to be captured. Since the particles can be separated and recovered into two types of substances, the recovered magnetic particles can be used more effectively.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a superelectric thick type magnetic separator according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a superelectric thick type magnetic separator according to a different embodiment of the present invention, and FIG. Super 1 in the figure is an explanatory diagram showing the magnetic field distribution of the superconducting magnet of the thick magnetic separator, Figure 4 is an explanatory diagram showing the magnetic field distribution of the superconducting magnet of the superelectric thick magnetic separator of Figure 2, and Figure 5 1 is a sectional view of a conventional example of a superelectric thick type magnetic separation device. 5: Fluid to be treated, 11: Inner filter, 12: Outer filter, 15: Inner superconducting coil (superconducting magnet), 16:
Outer superconducting coil (superconducting magnet) Figure 1 Figure 2 2'z Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1) A superconducting magnet and a filter made of 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, In a superconducting magnetic separation device in which the magnetic particles are attracted to a filter and removed from the fluid to be treated using a localized high gradient magnetic field generated around the wire, a superconducting magnet is connected to a cylindrical inner superconducting coil coaxially and oppositely to the magnetic particles. The filter consists of a polar cylindrical outer superconducting coil, an inner filter disposed inside the inner superconducting coil, and an outer filter disposed between the outer superconducting coil and the inner superconducting coil. A superconductor characterized in that the magnetic dipole moment of the inner superconducting coil and the dipole moment of the outer superconducting coil have almost equal absolute values and opposite polarities, and the fluid to be treated flows through the inner filter and the outer filter. shaped magnetic separation device.