JP6394619B2 - Magnetic sorting device and magnetic sorting method - Google Patents

Description

  The present invention relates to an apparatus and a screening method for magnetically sorting magnetic particles and nonmagnetic particles from a granular material containing magnetic particles, which is advantageously adapted to recovering iron from, for example, steel slag generated in an iron factory. .

  For example, in steelworks, steel slag generated from ironmaking and steelmaking processes contains about 20 to 50% by mass of iron. If this steel slag is disposed of as it is, the yield in the iron making flow will decrease, so iron is separated from the slag and reused in the iron making or steel making processes. As a method for separating iron, magnetic separation using magnetism is generally used. When a large amount of particles having a small particle size (5 mm or less) such as slag powder is processed by magnetic separation, the magnetic particles and non-magnetic particles are mixed and stacked in multiple layers. There is a problem that the iron concentration of the recovered material cannot be sufficiently increased because the frequency of selection with the non-magnetic particles being included is high. Various methods have been proposed to solve this problem.

That is, Patent Document 1 proposes a method in which an object to be sorted is passed through a spiral slider and a non-magnetic material is peeled off from the center by centrifugal force.
Further, Patent Document 2 proposes a method for preventing entrapment of non-magnetized materials by increasing the distance between the raw material supply conveyor and the magnet roll, and adsorbing the magnetized materials after they are suspended in the air.
Furthermore, Patent Document 3 proposes a method of rotating a magnet roll to cause a magnetic field fluctuation at a high speed and shaking off non-magnetized objects.

Japanese Patent Laid-Open No. 7-155639 JP 2004-351858 JP Japanese Patent No. 5773089

  In the technique described in Patent Document 1, in which the non-magnetized material is separated from the magnet side by centrifugal force, the magnetic force acts on the magnetized material similarly to the non-magnetized material, and the magnetized material belongs to the non-magnetized side. . Also, in the technique of adsorbing magnetic deposits at a distance from the magnets described in Patent Document 2, when the objects to be sorted are supplied in multiple layers, the magnetic deposits in the lower layer are embraced by the non-magnetic deposits. There is a problem that it belongs to the magnetized side.

  On the other hand, the above-described problem can be solved by the method described in Patent Document 3 in which the non-magnetized material is shaken off by the varying magnetic field generated by rotating the magnet roll at a high speed. However, the sorting object is often a collection of particles having various particle sizes, and the magnetic field fluctuation frequency suitable for separation differs for each particle size of the separation object. Generally, the larger the particle size, the lower the frequency and particle size. The smaller the is, the better the higher frequency is.Therefore, when sorting with high efficiency is desired, after classifying before magnetic separation, the rotational speed of the magnet roll is changed for each particle size and the magnetic field fluctuation frequency is adjusted. There is a need to improve this point.

  The present invention aims to improve the technique of shaking off non-magnetized materials by the above-mentioned fluctuating magnetic field, and does not require pretreatment such as classification even for separation objects having a particle size distribution. An object is to propose a device and a method for realizing it.

The inventors diligently studied how to solve the above-described problems, and have obtained the following knowledge.
That is, the magnet roll as the magnetic field applying means described in Patent Document 3 described above has magnets arranged at equal intervals in the circumferential direction so that the magnetic poles are alternately different as shown in FIG. 2 and FIG. The magnetic field fluctuation frequency is constant according to the number of rotations of the magnet roll. Therefore, as described above, it is necessary to adjust the magnetic field fluctuation frequency by changing the rotation speed of the roll for each particle size of the selection target.

  Therefore, the inventors, as shown in FIG. 1, about the magnet roll 2 in which the N pole magnet 1a and the S pole magnet 1b are fixed under an array in which the magnetic poles are alternately different in the circumferential direction of the roll cylinder. The magnets 1a and 1b were arranged so that the arrangement interval p between the magnets 1a and 1b adjacent to each other was not uniform. This prototype magnet roll 2 is rotated at high speed, and the frequency of the variable magnetic field when the magnets A to E pass radially inward of an arbitrary measurement point m on the surface of the guide roll 3 containing the magnet roll 2. Was measured. As a result, as shown in FIG. 2, it was newly found that the low frequency band and the high frequency band appear while the magnetic field frequency changes and the magnet roll 2 rotates once. Further, it has been found that even if the width w of each magnet in the roll circumferential direction is not uniform among the magnets, a low frequency band and a high frequency band appear. By changing the frequency of the variable magnetic field in this way, it becomes possible to shake off non-magnetized materials having a large particle size at low frequencies and non-magnetized materials having a small particle size at high frequencies. It has been found that it is possible to perform high-precision separation with little recovery loss of magnetic deposits on a sorting object having a diameter without prior classification.

The present invention is based on the above findings, and the gist thereof is as follows.
1. A first belt conveyor having a conveyor belt for conveying powder particles containing magnetic particles, and a second belt conveyor located above the first belt conveyor,
The second belt conveyor is
At least one pair of guide rolls;
A conveyor belt that is stretched between the pair of guide rolls and conveys a granular material containing magnetic particles,
Any one of the guide rolls is a hollow roll, and a plurality of magnets are arranged in the hollow portion along the inner peripheral surface of the guide roll in a row in which different magnetic poles are alternately arranged at intervals in the circumferential direction. Have a magnet roll,
The plurality of magnets are characterized in that either one or both of an arrangement interval in the circumferential direction of the magnet roll and a magnet width in the roll circumferential direction of each magnet are non-uniform.

2. At least one pair of guide rolls;
It said guide stretched between roll pair has a conveyor belt for conveying the granular material comprising magnetic particles, a,
Any one of the guide rolls is a hollow roll, and a plurality of magnets are arranged in the hollow portion along the inner peripheral surface of the guide roll in a row in which different magnetic poles are alternately arranged at intervals in the circumferential direction. Have a magnet roll,
The plurality of magnets are characterized in that either one or both of an arrangement interval in the circumferential direction of the magnet roll and a magnet width in the roll circumferential direction of each magnet are non-uniform.

3. 3. The magnetic separator according to 1 or 2 above, wherein a magnet roll having a plurality of magnets arranged at intervals of 1 mm or more at a narrowest portion is provided.

4). 4. The magnetic force sorting apparatus according to 1, 2, or 3, wherein magnets of the magnet roll have different adjacent magnetic poles in the circumferential direction.

5. 4. The magnetic force sorting apparatus according to 1, 2, or 3, wherein the magnets of the magnet roll include an arrangement in which magnetic poles adjacent in the circumferential direction are the same.

6). 6. A magnetic force sorting method using the magnetic force sorting device according to any one of 1 to 5, wherein a magnetic field change frequency F defined by the following formula (1) is 7.5 Hz or more at the widest part of the magnet arrangement interval: A magnetic force selection method, wherein magnetic particles and nonmagnetic particles are selected under the following conditions.
F = πφx / 60 (2p + w1 + w2) (1)
Where π: Circumference x: Magnet roll rotation speed [rpm]
φ: Diameter of magnet roll [mm]
p: Maximum magnet arrangement interval [mm]
w1, w2: Width of magnet 1 and magnet 2 across the maximum interval [mm]

  According to the present invention, for example, separation and recovery of iron can be realized from the steel slag with high quality and high recovery without performing prior classification on the steel slag discharged from the steel process. Moreover, since the incidental equipment required for prior classification is unnecessary, there is an advantage that the processing plant can be simplified as compared with the conventional one.

It is explanatory drawing which shows the structure of the magnetic roll which concerns on this invention. It is a figure which shows the result of having measured the frequency of the fluctuation | variation magnetic field when a several magnet passed. It is explanatory drawing which shows the magnetic sorting apparatus which concerns on Embodiment 1 of this invention. It is a perspective view which shows the structure of the magnet roll of this invention. It is explanatory drawing which shows other magnet roll arrangement | positioning of this invention. It is a perspective view which shows the structure of another magnet roll of this invention. It is explanatory drawing which shows the magnetic sorting apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the sorting result by a various magnetic sorter.

Next, the magnetic separator according to the present invention will be described in detail with reference to the drawings for each embodiment.
[Embodiment 1]
The apparatus according to Embodiment 1 shown in FIG. 3 includes a first belt conveyor A that conveys the granular material a, and the powder that is positioned above the first belt conveyor A and has been conveyed by the belt conveyor A. There is provided a second belt conveyor B that adsorbs the magnetic particles a ₁ from the particles a by magnetic force and separates them from the non-magnetic particles a ₂ .

  In the first belt conveyor A, 10 is a conveyor belt, 11 is a guide roll on the conveyor start end 12 side, and 13 is a guide roll on the conveyor end end 14 side. A conveyor belt 10 is formed by stretching the conveyor belt 10 between the guide rolls 11 and 13.

  In the second belt conveyor B, 20 is a conveyor belt, 3 is a guide roll on the conveyor start end 21 side, 22 is a guide roll on the conveyor end 23 side, and the conveyor belt 20 is stretched between the guide rolls 3 and 22 Thus, the belt conveyor B is configured. In the first embodiment, the guide roll 3 is configured to have a larger diameter than the guide roll 22, and the rotation axis of the guide roll 22 is positioned above the rotation axis of the guide roll 3, whereby the upper surface of the conveyor belt 20 (guide The upper belt portion between the roll 3 and the guide roll 22) is substantially horizontal. However, the upper surface of the conveyor belt 20 may be lowered toward the guide roll 22.

The position of the conveyor beginning 12 side of the belt conveyor A, the supply device 100 for supplying the powder or granular material a containing magnetic particles a ₁ on the conveyor belt 1 are disposed.

The magnetic particles a ₁ adsorbed and held on the belt conveyor B side are transported by the belt conveyor B and then discharged from the conveyor terminal portion 23 side. Below the conveyor terminal portion 23 of the belt conveyor B, a magnetic deposit collection unit 24 is provided. On the other hand, since the nonmagnetic particles fall below the conveyor start end 21 of the belt conveyor B, a non-magnetized substance recovery unit 25 is provided at that position.

  In the embodiment of FIG. 3, the conveyor start end 21 of the belt conveyor B is located close to the conveyor terminal end 14 of the belt conveyor A. Further, the guide rolls 11 and 13 of the belt conveyor A and the guide rolls 3 and 22 of the belt conveyor B are rotated in the opposite directions, and at the conveyor terminal end 14 of the belt conveyor A and the conveyor start end 21 of the belt conveyor B, The conveyor belts 10 and 20 are moving in the same direction.

  In the belt conveyor B, one of the guide rolls 3 and 22 is driven by driving means such as a motor. Usually, the guide roll 22 is a drive roll, and the guide roll 3 is a non-drive roll.

  In Embodiment 1, the magnet roll 2 having the plurality of magnets 1a and 1b is provided inside the guide roll 2 as described above. The magnet roll 2 is configured to be rotatable independently from the guide roll 3.

  As shown in FIG. 4, the magnet roll 2 is provided coaxially with the guide roll 3 inside the hollow guide roll 3, and can rotate independently of the guide roll 3. The magnet roll 2 has a plurality of magnets 1a and 1b arranged at predetermined intervals in the circumferential direction and the axial direction of the roll. A plurality of magnets are arranged over the entire circumference of the magnet roll 2 so that adjacent magnetic poles have N poles (1a) and S poles (1b) alternately. Further, in the axial direction of the magnet roll 2, a plurality of magnets are arranged so as to have the same magnetic pole.

  Here, the number of magnets 1a and 1b arranged in the roll circumferential direction and the mutual distance in the magnet roll axial direction are not particularly limited, but the arrangement interval between adjacent magnets 1a and 1b in the circumferential direction of the magnet roll 2 is not limited. It is important that one or both of p and the magnet width w in the roll circumferential direction of each magnet is not uniform.

  That is, if the magnets 1a and 1b are arranged so that at least one of the arrangement interval p and the magnet width w in the circumferential direction of the magnet roll 2 is non-uniform and the magnet roll 2 is rotated at high speed, the guide roll 3 The magnetic field strength on the surface can be varied at an indefinite frequency as shown in FIG. As a result, a vibration effect of the magnetic article by a variable magnetic field with an indefinite frequency can be obtained, so that high-precision magnetic separation can be realized for selection objects having various particle sizes.

  Further, in place of making one or both of the arrangement interval p and the magnet width w nonuniform, a plurality of magnets having the same pole are continuously arranged to realize nonuniform magnetic field fluctuations. You can also. That is, as shown in FIG. 5, a plurality of magnets 1 a are continuously arranged in the roll circumferential direction, and a plurality of magnets 1 b are continuously arranged in the roll circumferential direction, so that magnetic field fluctuations in the roll circumferential direction can be prevented. It can be made uniform. This continuous arrangement of homopolar magnets is applied to one or both of the magnets 1a and 1b, and the number of magnets to be continued may be arbitrary.

  In FIG. 4 showing the structure of the magnet roll 2, reference numeral 31 denotes a rotating shaft of the guide roll 2, and rotating shafts 32 at both ends of the magnet roll 2 are externally mounted on the rotating shaft 31 and a bearing 33 (for example, a metal bearing). , A bearing bearing or the like). However, the guide roll 3 and the magnet roll 2 can rotate independently of each other. Further, the roll shafts 31 and 32 may take various forms.

The magnet roll 2 is a roll that is rotated by means such as a motor. The rotation direction of the magnet roll 2 may be either the same direction as that of the guide roll 3 or the opposite direction, but it is preferably rotated in the opposite direction as shown in FIG. The magnet roll 2 is preferably rotated at a higher speed than the guide roll 3.
That is, the rotational direction of the magnet roll 2 is the same as (i) the direction of travel of the conveyor belt 20 (the direction of rotation of the guide roll 3), and (ii) the direction of travel of the conveyor belt 20 (the direction of rotation of the guide roll 3). Either direction. The magnetic particles have a transport force that tends to move in the direction opposite to the direction of rotation of the magnet roll 2 due to the effect of magnetic field fluctuations at an indefinite frequency of the rotating magnet roll 2. In the above case (i), the friction force of the conveying force to the magnetic particles that by the magnetic field, the conveyor belt 1 and the magnetic particles are the same direction. On the other hand, in the case of (ii) above, the conveying force and the frictional force are in opposite directions. However, in this case, since the larger the frictional force, magnetic particles are gradually being transported to the traveling direction of the conveyor belt 1. In either case, since a variable magnetic field at an indefinite frequency works, it is possible to select magnetic particles having different particle sizes.

  Here, the magnet arrangement interval p is preferably non-uniform according to the particle size distribution. For example, as the particle size distribution is wider, the ratio of the gap between the narrower and wider portions is increased. In addition, an interval suitable for a peak in the particle size distribution (a portion having a large weight ratio) is frequently used. Specifically, when there are many coarse grains, it is preferable to increase the portion with a wide interval, and when there are many fine particles, the portion with a narrow interval is increased. Similarly, the magnet width w is preferably adjusted in accordance with the above. Furthermore, it is preferable to adjust the arrangement of the homopolar magnets shown in FIG. 5 according to the above.

  The arrangement interval p is preferably 1 mm or more at the narrowest portion. That is, when the magnet gap p is less than 1 mm, the magnetic field circuit near the surface of the conveyor belt is closed, and when away from the surface of the conveyor belt, the magnetic field strength rapidly attenuates and the layer thickness of the unsorted material cannot be increased. There is a fear. In addition, when the arrangement interval p is 1 mm or more, the magnet roll can be manufactured with high accuracy.

Furthermore, when performing magnetic sorting by rotating the magnet roll, it is preferable to set the magnet roll frequency F defined by the following formula (1) to a condition that the frequency is 7.5 Hz or more in the widest portion of the arrangement interval. . By satisfying this condition, it is possible to reliably obtain a non-magnetized object shake-off effect due to magnetic field fluctuations.
F = πφx / 60 (2p + w1 + w2) (1)
Where π: Circumference x: Magnet roll rotation speed [rpm]
φ: Diameter of magnet roll [mm]
p: Maximum magnet spacing [mm]
w1, w2: Width of magnet 1 and magnet 2 across the maximum interval [mm]

In FIG. 4, the magnetic poles of one magnet 1 a or 1 b are arranged to be different magnetic poles on the inner side and the outer side in the radial direction of the magnet roll 2. The magnets may be installed so as to be aligned in the circumferential direction of the magnet roll 2. In this case, N pole, since S poles are disposed alternately, so that the separation of magnetic particles is efficiently. N poles and S poles may be installed across a non-uniform interval p between magnets, and N poles and S poles may be installed across the same interval p. The gap that forms the gap between the magnets may be filled with resin or the like, and a cover that covers the magnets of the magnet roll 2 may be provided.

  Further, as shown in FIG. 6, a plurality of magnets may be arranged with different magnetic poles in the axial direction of the magnet roll 2. With this arrangement, magnetic field fluctuations can be generated also in the axial direction of the magnet roll 2.

  Incidentally, although there is no particular restriction on the strength of the magnetic field by the magnets 1a and 1b, the maximum magnetic field strength on the surface of the magnet roll is preferably 2500 gauss or less in order to prevent heat generation due to the induced current. Regarding the particle size of the object to be sorted, there is a problem of heat generation of the magnetized material, so that it is preferably 10 mm or less. In particular, when recovering metallic iron from steel slag, the magnetic field strength is preferably about 500 gauss to 1500 gauss and the particle size is 5 mm or less.

Hereinafter, in conjunction with the function and operation of the magnetic force sorting apparatus shown in FIGS. 3 and 5, a magnetic force sorting method using this apparatus will be described.
In performing magnetic force sorting using this magnetic force sorting device, the feeding speed of the conveyor belt 20 may be set to a speed necessary for the processing process. The rotation speed of the magnet roll 2 is determined so that the change in the magnetic field is sufficiently high with respect to the belt feed speed. In particular, the rotational speed of the magnet roll 2 is preferably set so as to satisfy the condition of the above-described formula (1).

  In a state where the belt conveyors A and B are operating, the granular material a containing magnetic particles is supplied from the supply device 100 onto the conveyor belt 10 that is moving the belt conveyor A with a sufficient thickness. The granule a is conveyed to the conveyor terminal part 13. The granular material a conveyed by the conveyor belt 10 has its upper surface in contact with the lower surface of the conveyor start end 21 of the belt conveyor B in the vicinity of the conveyor terminal 13, and the granular material a is in contact with the conveyor terminal 13 of the belt conveyor A. The belt conveys between the conveyor start end portions 21 of the belt conveyor B. At this time, the magnetic field of the magnet roll 2 of the belt conveyor B is exerted on the granular material a.

  Here, in the case of the magnetic separator of FIG. 3 and FIG. 5, the magnetic particles in the granular material a adhere to the lower surface side of the belt conveyor B by the magnetic force of the magnet roll 2 so as to embrace the nonmagnetic particles. Then, it is conveyed by the conveyor belt 20. The magnetic particles in the powder a are subjected to the action of the magnetic fields of the magnets 1a and 1b included in the magnet roll 2. At that time, the strength of the magnetic field is instantaneously switched at various strengths by the rotation of the magnet roll 2. For the magnetic particles in the granular material layer, aggregation for each particle size → dispersion → aggregation → dispersion →... Is repeated.

  In addition, as shown in FIG. 1, since the magnet roll 2 rotates independently from the guide roll 3, (1) rotating the magnet roll 2 generates a mechanically high-speed magnetic field change. (2) Supply the granular material a with sufficient layer thickness into the changing magnetic field. (3) Magnetic particles with different particle sizes are magnetized while eliminating the magnetic particles' entrainment and inclusion. It moves to the roll 2 side, and the non-magnetic particles are removed to the side far from the magnet roll 2. (4) The non-magnetic particles fall by gravity at the conveyor start end 21 of the belt conveyor B, and the magnetic particles are the belt conveyor. It is carried while being sucked and held by B, and is discharged at the conveyor terminal portion 23 of the belt conveyor B. Therefore, even if the granular material a supplied to the conveyor belt 10 is sufficiently thick as shown in FIGS. 3 and 5, the magnetic particles can be efficiently magnetically sorted. That is, magnetic particles having various particle diameters can be efficiently and rapidly selected from the granular material a.

  In the apparatus of the first embodiment shown in FIG. 3 or 5, the magnet roll 2 rotates independently from the guide roll 3, so that the granular material a is conveyed along the guide roll 3 of the belt conveyor B. Furthermore, changes in the strength and direction of the magnetic field of 100 times or more can be easily applied. In addition, since the behavior of the ferromagnetic particles in the magnetic field varies depending on the target granular material a, the rotational speed of the magnet roll 2 can be adjusted so as to obtain appropriate performance.

Magnetic separation apparatus according to the first embodiment, since the magnetic particles rather by efficiently from granular material a as described above can be screened magnetic force at magnetic separator of the granular material a using this device, As shown in FIG. 3 and FIG. 5, the layer thickness is larger than the diameter of the smallest particle contained in the granular material a on the conveyor belt 10 of the belt conveyor A from the supply device 100 and the magnetic force acts sufficiently. It is desirable to supply the granular material. Specifically, the thickness of the granular material is 20 to 30 mm.

The apparatus according to the first embodiment includes a magnet provided on the inside of the guide roll 3 on the conveyor starting end 21 side of the belt conveyor B on the powder body a (powder body layer) conveyed by the belt conveyor A. 4 by applying a magnetic field, by sucking magnetic particles in the granular material a is shifted to the lower surface side of the belt conveyor B, and as to separate the magnetic particles. Therefore, the distance between the conveyor terminal end 14 of the belt conveyor A and the conveyor start end 21 of the belt conveyor B may be a size that allows the magnetic force of the magnet roll 2 to sufficiently act on the magnetic particles in the granular material a, Generally, the upper surface of the layer of the granular material a conveyed by the conveyor belt 10 of the belt conveyor A is in contact with the conveyor starting end 21 of the belt conveyor B, that is, the granular material layer is the conveyor terminal end 13 of the belt conveyor A. It is preferable that the belt conveyor B has a size that can be retracted between the conveyor start end portions 21 of the belt conveyor B.

[Embodiment 2]
FIG. 7 is an explanatory diagram showing a magnetic force sorting apparatus according to Embodiment 2 of the present invention. In the figure, reference numeral 20 denotes a conveyor belt that conveys the granular material a. The conveyor belt 20 is stretched between a pair of guide rolls 22 and 3 and guided to the guide rolls 22 and 3. Rotate and convey the granular material a in one direction. One of the guide rolls 22 and 3, that is, the guide roll 3 on the end side in the conveying direction of the granular material a of the conveyor belt 1 has a magnet roll 2 similar to the apparatus shown in FIG. Reference numeral 26 is a partition plate for distributing the magnetic particles a ₁ and non-magnetic particles a _2.

  Also in the second embodiment, magnetic particles having various particle diameters are efficiently and quickly selected from the powder a by the action of the magnet roll 2 as in the first embodiment shown in FIG. Can do.

  Examples of the present invention are shown below. Conventionally used belt pulley type magnetic separator (conventional example) for steel slag (particle size: 5 mm or less, Fe concentration: about 50 mass%) whose particle size is 5 mm or less by crushing Magnetic force sorting was performed by the magnetic force sorting device described in Patent Documents 1 to 3 (Comparative Examples 1 to 3) and the magnetic force sorting device (Invention Example) shown in FIG.

  Various specifications in the invention examples are as follows. That is, the outer diameter of the magnet roll 2 is 200 mm, the number of magnetic poles of the magnet is 14 (however, one pole is a pair of N pole and S pole), the magnet width w is uniform, the conveyor belts 10 and 20 The feed speed was 15 m / min, the rotation speed of the magnet roll 2 was 500 rpm, and the magnetic field strength at the conveyor belt portion in contact with the magnet roll 2 was 600 gauss. The supply layer thickness of the granular material on the conveyor belt 10 was 10 mm.

Various specifications of the conventional example and the comparative examples 1 to 3 are as follows.
・ Conventional example: Conveyor belt speed 15m / min, Conveyor belt surface magnetic field strength 600G, Slag layer thickness 10mm
Comparative Example 1 (Patent Document 1): Rotating magnet magnetic field strength of 600 G, rotating cylinder diameter of 400 mm, spiral selection rod inclination angle of 30 °, spiral selection rod width of 100 mm, slag layer thickness of 10 mm
Comparative Example 2 (Patent Document 2): Conveyor belt speed 15 m / min in contact with magnet, magnetic field strength 600 G on conveyor belt surface in contact with magnet, slag layer thickness 10 mm
Comparative Example 3 (Patent Document 3): Conveyor belt speed 15 m / min in contact with the magnet roll, conveyor belt magnetic field strength 600 G in contact with the magnet roll, magnet roll rotation speed 500 rpm, slag layer thickness 10 mm

  About the result of having investigated Fe purity with respect to the obtained magnetic deposit, it shows in FIG. The investigation was conducted by chemical analysis using fluorescent X-rays.

  In the conventional example and the comparative example 1, the magnetic particles embraced the nonmagnetic particles, and the iron concentration could not be sufficiently increased. Although the purity in Comparative Examples 2 and 3 was higher than these, the magnetic force sorting according to Comparative Example 2 did not completely remove the non-magnetic particles clinging to the magnetic particles. Due to the wide area, the effect of shaking off the non-magnetic particles was insufficient, and the purity of Fe was not as high as that of the selected product obtained by the inventive examples.

1a, 1b Magnet 2 Magnet rolls 3, 11, 13, 22 Guide rolls 12, 21 Conveyor start end portions 14, 23 Conveyor end portions 10, 20 Conveyor belts 31, 32 Rotating shaft 33 Bearing 24 Magnetized matter collecting portion 25 Non-magnetized matter collecting Part 26 Partition plate 100 Supply device A, B Belt conveyor a Granule p Arrangement interval w Magnet width

Claims (7)

A first belt conveyor having a conveyor belt for conveying powder particles containing magnetic particles, and a second belt conveyor located above the first belt conveyor,
The second belt conveyor is
At least one pair of guide rolls;
A conveyor belt that is stretched between the pair of guide rolls and conveys a granular material containing magnetic particles,
Any one of the guide rolls is a hollow roll, and a plurality of magnets are arranged in the hollow portion along the inner peripheral surface of the guide roll in a row in which different magnetic poles are alternately arranged at intervals in the circumferential direction. Have a magnet roll,
Wherein the plurality of magnets, magnetic separation apparatus, wherein the arrangement interval in the circumferential direction of the magnet roll is uneven. At least one pair of guide rolls;
A conveyor belt that is stretched between the pair of guide rolls and conveys a granular material containing magnetic particles,
Any one of the guide rolls is a hollow roll, and a plurality of magnets are arranged in the hollow portion along the inner peripheral surface of the guide roll in a row in which different magnetic poles are alternately arranged at intervals in the circumferential direction. Have a magnet roll,
Wherein the plurality of magnets, magnetic separation apparatus, wherein the arrangement interval in the circumferential direction of the magnet roll is uneven.   The magnetic separation apparatus according to claim 1, wherein the plurality of magnets have a magnet roll having an interval of 1 mm or more at a narrowest portion.   The magnetic force sorting apparatus according to claim 1, 2 or 3, wherein magnets of the magnet roll have different magnetic poles adjacent to each other in the circumferential direction.   4. The magnetic force sorting apparatus according to claim 1, wherein the magnets of the magnet roll include the same arrangement of magnetic poles adjacent in the circumferential direction. 6. The ratio of the interval between a narrow portion and a wide portion of the plurality of magnets is increased as the particle size distribution of the powder particles is wider. 6. Magnetic sorting device. A magnetic field selection method using the magnetic field separation device according to any one of claims 1 to 6 , wherein a magnetic field change frequency F defined by the following equation (1) is 7.5 Hz at a widest part of the arrangement interval of the magnets. A magnetic force sorting method, wherein the magnetic particles and the non-magnetic particles are sorted under the above conditions.
F = πφx / 60 (2p + w1 + w2) (1)
Where π: Circumference x: Magnet roll rotation speed [rpm]
φ: Diameter of magnet roll [mm]
p: Maximum magnet arrangement interval [mm]
w1, w2: Width of magnet 1 and magnet 2 across the maximum interval [mm]

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