A fine powder dry magnetic separator for reducing eddy current heating and its usage method

Abstract

The present invention discloses a fine powder dry magnetic separator for reducing eddy current heating and a using method thereof, which relates to the technical field of magnetic separators; a magnetic separation main frame, a magnetic separation cavity is opened inside the magnetic separation main frame, a feed pipe orifice is arranged at the top, and a tailing outlet and a concentrate outlet are respectively arranged at the bottom; a rotating magnetic roller assembly, including a sorting cylinder body and a magnetic system, the magnetic system includes a plurality of fan-shaped magnetic conduction blocks, and a high-resistance insulating material is filled between adjacent magnetic conduction blocks; an annular exciting coil, embedded inside the magnetic conduction blocks, and generates an alternating magnetic field perpendicular to the surface of the sorting cylinder body at the corresponding position when the annular exciting coil is energized; a feeding device, including a vibrating feeder and an inclined diversion plate, and convex diversion ribs are equidistantly distributed on the surface of the inclined diversion plate; the bottom of the inclined diversion plate located at the bottom is located above the feed pipe orifice; an inlet diameter-expanding member is installed at the bottom of the feed pipe orifice to solve the technical problems of reducing the influence of eddy current on the cylinder heating and uneven and uncontrollable feeding in a non-opening manner.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic separators, and particularly to a fine powder dry magnetic separator for reducing eddy current heating and a usage method thereof. Background Art

[0002] A dry magnetic separator is a magnetic separation equipment for sorting dry magnetic minerals, commonly used in industries such as ferrous metal mines. It generally uses a conventional magnetic separator to remove non-magnetic or weakly magnetic minerals from magnetic minerals. The working principle of the dry magnetic separator is based on the combined action of magnetic force and mechanical force. When the material enters the separation area, the magnetic material is magnetized under the action of the magnetic field and adsorbed on the surface of the cylinder body, and is carried to the designated position as the cylinder body rotates. The non-magnetic material is not affected by the magnetic field and naturally flows to another material outlet, thus realizing the separation of magnetic material and non-magnetic material.

[0003] The phenomenon that an induced current is generated in a whole conductor due to electromagnetic induction is called the eddy current phenomenon, which causes the separation cylinder body adsorbing ore materials to generate overheating. The magnetic field generated by the eddy current may cause some metal particles to be subjected to repulsive or attractive forces, thereby changing their movement trajectories.

[0004] In the prior art, for the drum of a magnetic separator in CN202122363914.2, a long slot hole is adopted, and a metal shielding material is combined to interrupt the electromagnetic induction that continuously generates eddy currents; however, in this way, the adsorbed metal materials are easy to accumulate in the long slot holes, and it is difficult to select and separate the magnetic materials.

[0005] Currently, the magnetic separator still has the following problems:

[0006] 1. The feeding cannot be uniform, and the granular material is easy to accumulate during feeding, which is likely to cause the loss of target magnetic metals;

[0007] 2. The feeding of the material is easy to impact the cylinder body;

[0008] Therefore, we provide a fine powder dry magnetic separator for reducing eddy current heating and a usage method thereof to solve the above problems. Summary of the Invention

[0009] The purpose of the present invention is to make up for the deficiencies of the prior art, and provide a fine powder dry magnetic separator for reducing eddy current heating and a usage method thereof to solve the technical problems of reducing the influence of eddy current on the cylinder body heating and uneven feeding and uncontrollability without an opening method.

[0010] To solve the above technical problems, the present invention provides the following technical solutions:

[0011] A fine powder dry magnetic separator for reducing eddy current heating, comprising:

[0012] The magnetic separation main frame has a magnetic separation cavity opened inside it, a feed pipe orifice is provided at the top, and a tailing outlet and a concentrate outlet are respectively provided at the bottom.

[0013] The rotating magnetic roller assembly includes a sorting cylinder body and a magnetic system. The magnetic system includes a plurality of fan-shaped magnetic conduction blocks, which are arranged at intervals along the circumference, and high-resistance insulating materials are filled between adjacent magnetic conduction blocks.

[0014] The annular exciting coil is embedded inside the magnetic conduction block, and an alternating magnetic field perpendicular to the surface of the sorting cylinder body at the corresponding position is generated when the annular exciting coil is energized.

[0015] The feeding device includes a vibrating feeder and an inclined diversion plate. The surface of the inclined diversion plate is provided with equally spaced convex diversion ribs; the bottom of the inclined diversion plate at the bottom is located above the feed pipe orifice; an inlet diameter-expanding member is installed at the bottom of the feed pipe orifice.

[0016] The temperature monitoring system includes an infrared sensor and a feedback controller, and the feedback controller regulates the rotation speed of the rotating magnetic roller assembly and the current frequency of the annular exciting coil.

[0017] In a further technical solution, a magnetic conduction cavity and a fixed column are opened in the magnetic conduction block, and the annular exciting coil is sleeved outside the fixed column.

[0018] The rotating magnetic roller assembly further includes a fixed plate and a central fixed cylinder. A guide cylinder is opened in the fixed plate, and the energizing circuit and the control circuit of the annular exciting coil are connected to the central fixed cylinder through the guide cylinder and extend outside the magnetic separation main frame.

[0019] An installation cylinder part is provided on the sorting cylinder body and is installed on the central fixed cylinder and is connected through an installation connecting bearing; a connecting groove is opened in the central fixed cylinder located inside the installation cylinder part; the outer ring of the connecting bearing is connected to the installation cylinder part, and the inner ring of the connecting bearing is connected to the inner wall of the connecting groove.

[0020] The installation cylinder part is connected to an external driving structure to make the installation cylinder part rotate relative to the central fixed cylinder. The driving structure can be a transmission method such as belt drive, gear drive, sprocket drive, etc. For example, in the belt drive method, a belt wheel can be installed on the installation cylinder part of the sorting cylinder body and connected to the transmission belt wheel driven by an external driving motor through a connecting transmission belt.

[0021] In a further technical solution, the magnetic conduction block includes silicon steel sheets, and multiple groups of silicon steel sheets are arranged in layers and laminated; a nano-aluminum oxide insulating coating is coated between the upper and lower silicon steel sheets, and the lamination direction is parallel to the axis of the central fixed cylinder.

[0022] In a further technical solution, the high-resistance insulating material is a silicon carbide ceramic matrix composite material, and the resistivity > 10^ 4Ω·m, the difference in the thermal expansion coefficient between the high-resistance insulating material and the magnetic conduction block is < 5%.

[0023] In a further technical solution, the magnetic system includes an upper arc plate, a pressing plate one, and a pressing plate two. The upper arc plate is fixedly mounted upward on the central fixing cylinder; both the pressing plate one and the pressing plate two are pressed on the upper and lower sides of multiple groups of magnetic conduction blocks, and the upper arc plate and the pressing plate one are connected by a connecting support plate;

[0024] The two ends of the pressing plate one and the pressing plate two are connected.

[0025] In a further technical solution, multiple layers of the inclined diversion plates are provided and are located at the output end of the vibrating feeder; and they are inclined downward towards the feed pipe orifice;

[0026] The height of the raised diversion ribs is 3 - 5 mm, the inclined diversion plates are distributed in multiple layers, and the distance between adjacent raised diversion ribs is 1.2 - 1.5 times the average particle size of the ore.

[0027] In a further technical solution, the raised diversion ribs include a guiding strip and a fork strip. The guiding strip is inclined along the surface of the inclined diversion plate, and multiple groups of fork strips are provided.

[0028] In a further technical solution, the feedback controller dynamically adjusts the rotational speed according to the temperature data so that the eddy current loss power satisfies the formula:

[0029]

[0030] In the formula, k is the material constant, B is the magnetic induction intensity, f is the current frequency, and δ is the width of the magnetic conduction block segmentation gap.

[0031] In a further technical solution, a fixing frame is installed on the magnetic separation main frame, and a laser particle size counter is installed on the fixing frame;

[0032] The inlet diameter-expanding part includes two groups of symmetrically distributed baffle plates. Hinge interfaces are provided at the tops of the two groups of baffle plates, and they are installed in the magnetic separation main frame through a mounting shaft;

[0033] A bidirectional lead screw is installed on the side of the feed pipe orifice facing away from the hinge interface. Fixing blocks are provided in the middle and at both ends of the bidirectional lead screw, and they are fixed to the magnetic separation main frame; position bearings are installed in the fixing blocks at both ends and are connected to the ends of the bidirectional lead screw. A protective cover is installed at the bottom of the bidirectional lead screw;

[0034] Sliding grooves are provided on the baffle plates, and lower sliding blocks are installed in the sliding grooves. The lower sliding blocks are restricted in the sliding grooves and a upper nut seat is rotatably connected to the lower sliding blocks. The upper nut seat moves on the bidirectional lead screw; a bevel gear box is installed at the end of the bidirectional lead screw, and a switch reduction motor is installed and connected to the magnetic separation main frame.

[0035] A method for using a fine powder dry magnetic separator to reduce eddy current heating, comprising the following steps:

[0036] Step a. Start the rotating magnetic roller assembly. After being modulated by an external power supply device, an alternating current is applied to the annular excitation coil through the central fixed cylinder and the guide cylinder to generate a radial alternating magnetic field perpendicular to the surface of the magnetic roller;

[0037] Initial state: The initial value of the magnetic induction intensity of the alternating magnetic field is 0.3 - 1.2T, the frequency is 50 - 150Hz, and the magnetic field direction is orthogonal to the movement direction of the ore;

[0038] Step b. Feed the ore to the surface of the magnetic roller through a vibrating feeder and a multi-layer inclined diversion plate. The wavy diversion ribs of the diversion plate disperse the ore axially on the magnetic roller to form a uniform material layer with a thickness fluctuation ≤ ±1.5mm; the vibration frequency of the diversion plate is 20 - 40Hz, the wavy period of the diversion ribs is 1.5 - 2 times the average particle size of the ore, and the adjustable range of the inclination angle of the diversion plate is 45° - 60°;

[0039] Step c. Real-time monitor the temperature distribution on the surface of the magnetic roller. When the local temperature exceeds the set threshold, the feedback controller synchronously reduces the rotational speed of the magnetic roller and increases the excitation current frequency; the feedback controller dynamically adjusts the rotational speed according to the temperature data so that the eddy current loss power satisfies the formula:

[0040]

[0041] It is necessary to pay attention to determining its critical maximum value;

[0042] Step d. Detect the particle concentration in the feeding device through a laser particle size counter;

[0043] Step e. According to the detected concentration, it is transmitted to the control cabinet for data analysis, and then the speed reduction motor is controlled through the control switch. The bevel gearbox drives the bidirectional lead screw to rotate. The upper nut seats on both sides of the bidirectional lead screw move to both sides, driving the lower slider to move outwards, driving the rotation of two groups of baffle plates connected by hinges, thereby opening the communication area with the feeding pipe orifice, and thus controlling the feeding speed;

[0044] Step f. Synchronously, an infrared sensor is installed in the magnetic separation main frame to detect the surface temperature of the sorting cylinder body, and the transmission speed of the installation cylinder part is controlled through the driving structure.

[0045] Compared with the prior art, the following beneficial effects are achieved:

[0046] The alternating current adopted by the present invention changes the magnetic field in the toroidal exciting coil, which can meet the sorting requirements of different magnetic minerals and does not require replacing the equipment hardware. It also responds in real time to the changes in the particle size and humidity of the ore through a feedback controller. By installing high-resistance insulating materials between adjacent magnetic conduction blocks, the present invention makes the magnetic induction lines as perpendicular as possible to the vertical direction of the sorting cylinder, and interrupts the continuous magnetic induction caused by the traditional integral magnetic conduction block, reducing the continuous increase of the eddy current phenomenon, thereby reducing the heating temperature and persistence of the eddy current on the sorting cylinder.

[0047] In the present invention, the rotation of the bidirectional lead screw is driven by bevel gears. When the two upper nut seats on the bidirectional lead screw move to both sides, they rotate around the hinge joint, driving the lower slider to move on the sliding groove, avoiding jamming, and achieving the effect of a rotating switch under the feed pipe orifice, and can synchronously control the feeding speed.

[0048] By installing multiple groups of inclined guide plates at the outlet of the vibrating feeder and discharging materials obliquely through the raised guide ribs, the present invention achieves the technical effect of uniform discharge of materials. Brief Description of the Drawings

[0049] Figure 1 is a schematic cross-sectional structure view of the fine powder dry magnetic separator of the present invention;

[0050] Figure 2 is Figure 1 an enlarged view of part A of

[0051] Figure 3 is a schematic structure view of the toroidal exciting coil of Embodiment 1 of the present invention installed in the magnetic conduction block;

[0052] Figure 4 is a schematic structure view of the sorting cylinder of the present invention;

[0053] Figure 5 is a schematic structure view of the fixing plate and the central fixing cylinder magnetic system of the present invention;

[0054] Figure 6 is a schematic cross-sectional connection view of the central fixing cylinder and the sorting cylinder of the present invention;

[0055] Figure 7 is a partial schematic view inside the vibrating feeder of the present invention;

[0056] Figure 8 is Figure 7 an enlarged structure view at position B of

[0057] Figure 9 is a front view of the inclined guide plate of Embodiment 2 of the present invention;

[0058] Figure 10Schematic cross-sectional structure diagram of the fine powder dry magnetic separator according to Embodiment 3 of the present invention;

[0059] Figure 11 Top view schematic diagram of the inlet diameter-expanding part under the feed pipe orifice of the present invention;

[0060] Figure 12 Schematic structure diagram of the baffle plate of the present invention.

[0061] In the figure:

[0062] 1. Magnetic separation main frame; 11. Feed pipe orifice; 12. Tailings outlet; 13. Concentrate outlet;

[0063] 2. Rotating magnetic roller assembly; 21. Sorting cylinder body; 22. Magnetic system; 23. Magnetic conduction block; 24. High-resistance insulating material; 25. Fixed plate; 26. Central fixed cylinder; 27. Connecting bearing;

[0064] 211. Installation cylinder part; 231. Fixed column; 251. Guide cylinder; 232. Silicon steel sheet; 233. Nano-aluminum oxide insulating coating; 221. Upper arc plate; 222. Pressing plate one; 223. Pressing plate two; 224. Support plate;

[0065] 3. Ring-shaped exciting coil;

[0066] 4. Feeding device; 41. Vibrating feeder; 42. Inclined guide plate; 43. Raised guide rib; 431. Guide bar; 432. Fork bar;

[0067] 5. Inlet diameter-expanding part; 51. Baffle plate; 52. Hinge joint; 53. Bidirectional lead screw; 54. Fixed block; 55. Position bearing; 56. Protective cover; 57. Sliding groove; 58. Lower slider; 59. Upper nut seat; 510. Bevel gear box; 511. Switch reduction motor;

[0068] 6. Temperature monitoring system; 61. Infrared sensor; 62. Feedback controller;

[0069] 7. Fixed frame; 71. Laser particle size counter; Specific implementation mode

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0071] Embodiment 1

[0072] Please refer to Figure 1-8As shown, the present invention provides a technical solution, a dry fine powder magnetic separator for reducing eddy current heating, including:

[0073] A magnetic separation main frame 1, with a magnetic separation cavity opened inside the magnetic separation main frame 1, a feed pipe orifice 11 provided at the top, and a tailing outlet 12 and a concentrate outlet 13 respectively provided at the bottom; A rotating magnetic roller assembly 2, including a sorting cylinder body 21 and a magnetic system 22, the magnetic system 22 includes a plurality of fan-shaped magnetic conduction blocks 23, and they are arranged at intervals along the circumference, and a high-resistance insulating material 24 is filled between adjacent magnetic conduction blocks 23; The sorting cylinder body 21 is located inside the magnetic separation cavity; An annular excitation coil 3, embedded inside the magnetic conduction block 23, generating an alternating magnetic field perpendicular to the surface of the sorting cylinder body 21 at the corresponding position when the annular excitation coil 3 is energized; A feeding device 4, including a vibrating feeder 41 and an inclined guide plate 42, and raised guide ribs 43 are equidistantly distributed on the surface of the inclined guide plate 42; The bottom of the inclined guide plate 42 located at the bottom is located on the feed pipe orifice 11; An inlet diameter-expanding part 5 is installed at the bottom of the feed pipe orifice 11; A temperature monitoring system 6, including an infrared sensor 61 and a feedback controller 62, and the feedback controller 62 regulates the rotation speed of the rotating magnetic roller assembly 2 and the current frequency of the annular excitation coil 3.

[0074] As Figure 3 shown, a magnetic conduction cavity and a fixing column 231 are opened inside the magnetic conduction block 23, and the annular excitation coil 3 is sleeved outside the fixing column 231;

[0075] The rotating magnetic roller assembly 2 further includes a fixing plate 25 and a central fixing cylinder 26, a guide cylinder 251 is opened inside the fixing plate 25, and the energizing circuit and the control circuit of the annular excitation coil 3 are connected to the central fixing cylinder 26 through the guide cylinder 251 and extend outside the magnetic separation main frame 1;

[0076] An installation cylinder part 211 is provided on the sorting cylinder body 21, and it is installed on the central fixing cylinder 26 and is connected through an installation connecting bearing 27; A connecting groove is opened inside the central fixing cylinder 26 located inside the installation cylinder part 211; The outer ring of the connecting bearing 27 is connected to the installation cylinder part 211, and the inner ring of the connecting bearing 27 is connected to the inner wall of the connecting groove;

[0077] The installation cylinder part 211 is connected to an external driving structure, so that the installation cylinder part 211 rotates relative to the central fixing cylinder 26. The driving structure can be a driving method such as belt drive, gear drive, sprocket drive, etc. For example, in the case of belt drive, a belt pulley can be installed on the installation cylinder part of the sorting cylinder body and connected to the belt pulley driven by an external driving motor through a connecting transmission belt. It is not drawn in the figure and should be considered according to actual use.

[0078] The magnetic conduction block 23 includes silicon steel sheets 232. Multiple groups of silicon steel sheets 232 are provided and laminated layer by layer. A nano-aluminum oxide insulating coating 233 is coated between the upper and lower silicon steel sheets 232, and the lamination direction is parallel to the axis of the central fixed cylinder 26.

[0079] The high-resistance insulating material 24 is a silicon carbide ceramic matrix composite material with a resistivity > 10^ 4 Ω·m. The difference between the thermal expansion coefficient of the high-resistance insulating material 24 and that of the magnetic conduction block 23 is < 5%.

[0080] As Figure 5 shown, the magnetic system 22 includes an upper arc plate 221, a first pressing plate 222, and a second pressing plate 223. The upper arc plate 221 is fixedly mounted on the central fixed cylinder 26 upwards. Both the first pressing plate 222 and the second pressing plate 223 are pressed against the upper and lower sides of multiple groups of magnetic conduction blocks 23, and the upper arc plate 221 and the first pressing plate 222 are connected by a connecting support plate 224. The two ends of the first pressing plate 222 and the second pressing plate 223 are connected.

[0081] Combined with Figure 7 and Figure 8 shown, multiple layers of the inclined diversion plates 42 are provided and located at the output end of the vibrating feeder 41, and are inclined downwards towards the feed pipe orifice 11.

[0082] The height of the raised diversion ribs 43 is 3 - 5 mm. The inclined diversion plates 42 are distributed in multiple layers, and the distance between adjacent raised diversion ribs 43 is 1.2 - 1.5 times the average particle size of the ore.

[0083] The feedback controller 62 dynamically adjusts the rotational speed according to the temperature data, so that the eddy current loss power satisfies the formula:

[0084]

[0085] In the formula, k is a material constant, B is the magnetic induction intensity, f is the current frequency, and δ is the width of the segmentation gap of the magnetic conduction block 23. The square term of B indicates that the magnetic field intensity has the greatest influence on the loss. Therefore, controlling the magnetic field intensity is the key to reducing the loss. The setting of the 1.5th power of the frequency f reflects the non-linear growth of the eddy current loss at high frequencies and is related to the skin effect. The higher the frequency, the smaller the skin depth, but the loss increases faster. The negative exponent of δ indicates that increasing the width δ of the segmentation gap can significantly reduce the loss, because the increase in the gap interrupts the continuous path of the eddy current, reduces the flow area of the eddy current, and thus reduces the loss. Segmentation, where σ is the material conductivity; d is the single-piece thickness of the magnetic conduction block; η_segmentation is the segmentation structure efficiency coefficient.

[0086] The design principle of the foregoing formula:

[0087] First, the magnetic field intensity (B2 Basis: In the classical eddy current loss formula, the loss is proportional to the square of the magnetic field strength. Since eddy currents are generated by the current induced by an alternating magnetic field in a magnetic material, their energy is directly related to the magnetic field energy density.

[0088] Among them, setting the frequency (f 1.5 ): Nonlinear correction: In traditional theory, the eddy current loss is proportional to f 2 , but this formula is adjusted to f 1.5 . The reasons include: Split design of the magnetic conduction block: The gap (δ) blocks the eddy current path, inhibits the diffusion of eddy currents at high frequencies, and weakens the influence of frequency; Skin effect: At high frequencies, the current is concentrated on the surface layer of the material, the equivalent cross-sectional area of conduction decreases, and the growth rate of the loss slows down.

[0089] Among them, setting the gap width ( ): Geometric blocking effect: Increasing the gap shortens the length of the eddy current loop, reduces the induced electromotive force; increases the resistance of the eddy current path and reduces the eddy current intensity.

[0090] Advantages of this embodiment:

[0091] 1. Split design of magnetic poles

[0092] The sector-shaped magnetic conduction blocks are isolated by high-resistance insulating materials, cutting off the continuous conductive loop, reducing the eddy current path length by more than 70%.

[0093] The laminated structure of silicon steel sheets confines the eddy currents within a single magnetic conduction block. Combined with the nano-aluminum oxide insulating coating, the eddy current loss is reduced to 18% - 25% of that of the traditional integral magnetic roller.

[0094] 2. Synergistic effect of uniform material distribution

[0095] The wavy arrangement of the flow guiding ribs generates a turbulence effect, making the standard deviation of the uniformity of the ore material distribution < 0.15 and avoiding sudden changes in local magnetic permeability.

[0096] Compared with the existing permanent magnet magnetic separation method, the present invention uses an annular excitation coil to generate a magnetic field by alternating current, and has the following advantages:

[0097] 1. It can adapt to the separation requirements of different magnetic minerals (such as weakly magnetic hematite and strongly magnetic magnetite), and there is no need to replace the equipment hardware;

[0098] 2. It can respond in real time to changes in the particle size and humidity of the ore material through a feedback controller;

[0099] 3. Compared with the fixed magnetic field of a permanent magnet, the winding direction of the coil and the current polarity can be programmably controlled to achieve flexible switching between a radial, axial or composite magnetic field.

[0100] By installing high-resistance insulating materials between adjacent magnetic conduction blocks, the present invention enables the magnetic induction lines to be as perpendicular as possible to the vertical direction of the sorting cylinder, breaks the continuous magnetic induction brought by the traditional integral magnetic conduction block, reduces the continuous increase of the eddy current phenomenon, and thus reduces the heating temperature and persistence of the eddy current on the sorting cylinder.

[0101] Embodiment 2

[0102] As Figure 9 shown, this is another implementation scheme of the present invention. On the basis of Embodiment 1, convex diversion ribs are provided that can slide to make the ore material uniform. The convex diversion ribs 43 include a guiding strip 431 and a fork strip 432. The guiding strip 431 is inclined along the surface of the inclined diversion plate 42, and multiple groups of fork strips 432 are provided.

[0103] Embodiment 3

[0104] As Figure 10-12 shown, this is another implementation scheme of the present invention. On the basis of Embodiment 1, a fixed frame 7 is installed on the magnetic separation main frame 1, and a laser particle size counter 71 is installed on the fixed frame 7;

[0105] The inlet diameter-expanding part 5 includes two groups of symmetrically distributed baffle plates 51. Hinge interfaces 52 are provided at the tops of the two groups of baffle plates 51 and are installed in the magnetic separation main frame 1 through a mounting shaft;

[0106] As Figure 11 , Figure 11 is a structural schematic of the inlet diameter-expanding part under the feeding pipe orifice from a top-down perspective. A bidirectional lead screw 53 is installed on the side of the feeding pipe orifice 11 facing away from the hinge interface 52. Fixed blocks 54 are provided in the middle and at both ends of the bidirectional lead screw 53 and are fixed to the magnetic separation main frame 1; Position bearings 55 are installed in the two fixed blocks 54 at both ends and are connected to the ends of the bidirectional lead screw 53. A protective cover 56 is installed at the bottom of the bidirectional lead screw 53; In terms of the feeding closure, a fitting design of the two groups of baffle plates can be considered.

[0107] Sliding grooves 57 are provided on the baffle plates 51, and lower sliding blocks 58 are installed in the sliding grooves 57. The lower sliding blocks 58 are restricted in the sliding grooves 57 and upper nut seats 59 are rotatably connected to the lower sliding blocks 58. The upper nut seats 59 move on the bidirectional lead screw 53; A bevel gear box 510 is installed at the end of the bidirectional lead screw 53 and is connected to a switch reduction motor 511 installed on the magnetic separation main frame 1. When the two upper nut seats on the bidirectional lead screw move towards both sides, they rotate around the hinge interface, driving the lower sliding blocks to move on the sliding grooves, avoiding jamming and achieving the effect of a rotating switch.

[0108] A method for using a fine powder dry magnetic separator for reducing eddy current heating includes the following steps:

[0109] Step a. Start the rotating magnetic roller assembly 2. After being modulated by an external power supply device, an alternating current is applied to the annular excitation coil 3 through the central fixed cylinder 26 and the guide cylinder 251 to generate a radial alternating magnetic field perpendicular to the surface of the magnetic roller.

[0110] Initial state: The initial value of the magnetic induction intensity of the alternating magnetic field is 0.3 - 1.2 T, the frequency is 50 - 150 Hz, and the magnetic field direction is orthogonal to the movement direction of the ore.

[0111] Step b. Feed the ore to the surface of the magnetic roller through the vibrating feeder 41 and the multi-layer inclined diversion plate 42. The raised diversion ribs 43 of the inclined diversion plate 42 disperse the ore in the axial direction of the magnetic roller to form a uniform material layer with a thickness fluctuation of ≤ ±1.5 mm. The vibration frequency of the inclined diversion plate is 20 - 40 Hz, the wave period of the raised diversion ribs is 1.5 - 2 times the average particle size of the ore, and the adjustable range of the inclination angle of the diversion plate is 45° - 60°.

[0112] Step c. Monitor the temperature distribution on the surface of the magnetic roller in real time. When the local temperature exceeds the set threshold, the feedback controller 62 synchronously reduces the rotation speed of the magnetic roller and increases the excitation current frequency. The feedback controller 62 dynamically adjusts the rotation speed according to the temperature data so that the eddy current loss power satisfies the formula:

[0113]

[0114] It is necessary to determine its critical maximum value.

[0115] Step d. Detect the particle concentration in the feeding device 4 through the laser particle size counter 71.

[0116] Step e. According to the detected concentration, it is transmitted to the control cabinet for data analysis. Then, by controlling the switch of the reduction motor 511, the bevel gear box 510 is controlled to drive the bidirectional lead screw 53 to rotate. The upper nut seats 59 on both sides of the bidirectional lead screw 53 move to both sides, driving the lower slider 58 to move outwards, driving the two groups of baffle plates 51 connected by hinges to rotate, thereby opening the communication area with the feed pipe orifice 11, and thus controlling the feed speed.

[0117] Step f. Synchronously, an infrared sensor 61 is installed in the magnetic separation main frame 1 to detect the surface temperature of the sorting cylinder 21, and the driving speed of the installation cylinder part 211 is controlled through the driving structure.

[0118] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

[0119] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only includes an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A dry micro - powder magnetic separator for reducing eddy current heating, characterized in that, Comprising: A magnetic separation main frame (1), a magnetic separation cavity is provided inside the magnetic separation main frame (1), a feed pipe orifice (11) is arranged at the top, and a tailing outlet (12) and a concentrate outlet (13) are respectively arranged at the bottom; A rotating magnetic roller assembly (2), including a sorting cylinder body (21) and a magnetic system (22), the magnetic system (22) includes a plurality of fan-shaped magnetic conduction blocks (23), and they are arranged at intervals along the circumference, and a high-resistance insulating material (24) is filled between adjacent magnetic conduction blocks (23); the sorting cylinder body (21) is located inside the magnetic separation cavity; An annular exciting coil (3), embedded inside the magnetic conduction block (23), generating an alternating magnetic field perpendicular to the surface of the sorting cylinder body (21) at the corresponding position when the annular exciting coil (3) is energized; A feeding device (4), including a vibrating feeder (41) and an inclined diversion plate (42), and convex diversion ribs (43) with equidistant distribution are arranged on the surface of the inclined diversion plate (42); the bottom of the inclined diversion plate (42) at the bottom is located on the feed pipe orifice (11); an inlet diameter-expanding part (5) is installed at the bottom of the feed pipe orifice (11); A temperature monitoring system (6), including an infrared sensor (61) and a feedback controller (62), and the feedback controller (62) regulates the rotation speed of the rotating magnetic roller assembly (2) and the current frequency of the annular exciting coil (3); A magnetic conduction cavity and a fixing column (231) are provided inside the magnetic conduction block (23), and the annular exciting coil (3) is sleeved outside the fixing column (231); The rotating magnetic roller assembly (2) further includes a fixing plate (25) and a central fixing cylinder (26), a guide cylinder (251) is provided inside the fixing plate (25), and the energizing circuit and the control circuit of the annular exciting coil (3) are connected to the central fixing cylinder (26) through the guide cylinder (251) and extend outside the magnetic separation main frame (1); An installation cylinder part (211) is provided on the sorting cylinder body (21), and it is installed on the central fixing cylinder (26) and connected through an installation connecting bearing (27); a connecting groove is provided inside the central fixing cylinder (26) located inside the installation cylinder part (211); the outer ring of the connecting bearing (27) is connected to the installation cylinder part (211), and the inner ring of the connecting bearing (27) is connected to the inner wall of the connecting groove; The installation cylinder part (211) is connected to an external driving structure, so that the installation cylinder part (211) rotates relative to the central fixing cylinder (26); The magnetic system (22) includes an upper arc-shaped plate (221), a pressing plate one (222) and a pressing plate two (223), the upper arc-shaped plate (221) is fixed upward on the central fixing cylinder (26); both the pressing plate one (222) and the pressing plate two (223) are pressed on the upper and lower sides of multiple magnetic conduction blocks (23), and the upper arc-shaped plate (221) and the pressing plate one (222) are connected through a connecting support plate (224); Both ends of the pressing plate one (222) and the pressing plate two (223) are connected; A fixing frame (7) is installed on the magnetic separation main frame (1), and a laser particle size counter (71) is installed on the fixing frame (7); The imported diameter-expanding part (5) includes two groups of symmetrically distributed baffle plates (51). At the top of the two groups of baffle plates (51), there are hinge interfaces (52), and they are installed in the magnetic separation main frame (1) through mounting shafts; On one side of the feed pipe orifice (11) facing away from the hinge interface (52), a bidirectional lead screw (53) is installed. Fixing blocks (54) are provided in the middle and at both ends of the bidirectional lead screw (53), and they are fixed to the magnetic separation main frame (1). Position bearings (55) are installed in the fixing blocks (54) at both ends and are connected to the ends of the bidirectional lead screw (53). A protective cover (56) is installed at the bottom of the bidirectional lead screw (53); Sliding grooves (57) are formed in the baffle plates (51), and lower sliding blocks (58) are installed in the sliding grooves (57). The lower sliding blocks (58) are restricted in the sliding grooves (57), and upper nut seats (59) are rotatably connected to the lower sliding blocks (58). The upper nut seats (59) move on the bidirectional lead screw (53). A bevel gear box (510) is installed at the end of the bidirectional lead screw (53), and a switch reduction motor (511) is connected to the magnetic separation main frame (1).

2. The dry micro powder magnetic separator for reducing eddy current heating according to claim 1, wherein The magnetic conductive block (23) includes silicon steel sheets (232). Multiple groups of silicon steel sheets (232) are provided and laminated layer by layer. A nano-aluminum oxide insulating coating (233) is coated between the upper and lower silicon steel sheets (232), and the lamination direction is parallel to the axis of the central fixed cylinder (26).

3. The dry fine powder magnetic separator for reducing eddy current heating according to claim 2, wherein The high-resistance insulating material (24) is a silicon carbide ceramic matrix composite material with a resistivity > 10^4 Ω·m, and the difference in the thermal expansion coefficient between the high-resistance insulating material (24) and the magnetic conductive block (23) is < 5%.

4. A fine powder dry magnetic separator for reducing eddy current heating according to claim 3, characterized in that, The inclined diversion plates (42) are arranged in multiple layers and are located at the output end of the vibrating feeder (41); and they are inclined downward from top to bottom towards the feed pipe orifice (11); The height of the raised diversion ribs (43) is 3 - 5 mm. The inclined diversion plates (42) are distributed in multiple layers, and the distance between adjacent raised diversion ribs (43) is 1.2 - 1.5 times the average particle size of the ore.

5. A fine powder dry magnetic separator for reducing eddy current heating according to claim 4, characterized in that, The raised diversion ribs (43) include guiding strips (431) and fork strips (432). The guiding strips (431) are inclined along the surface of the inclined diversion plates (42), and multiple groups of fork strips (432) are provided.

6. A fine powder dry magnetic separator for reducing eddy current heating according to claim 5, characterized in that, The feedback controller (62) dynamically adjusts the rotational speed according to the temperature data so that the eddy current loss power satisfies the formula: ； In the formula, k is a material constant, B is the magnetic induction intensity, f is the current frequency, and δ is the width of the split gap of the magnetic conductive block (23).

7. A method for using a fine powder dry magnetic separator for reducing eddy current heating, which uses the fine powder dry magnetic separator for reducing eddy current heating described in claim 1; characterized in that, It also includes the following steps: Step a. Start the rotating magnetic roller assembly (2). After being modulated by an external power supply device, an alternating current is applied to the annular exciting coil (3) through the central fixed cylinder (26) and the guide cylinder (251) to generate a radial alternating magnetic field perpendicular to the surface of the magnetic roller; Initial state: The initial value of the magnetic induction intensity of the alternating magnetic field is 0.3 - 1.2 T, the frequency is 50 - 150 Hz, and the magnetic field direction is orthogonal to the movement direction of the ore. Step b. Feed ore to the surface of the magnetic roller through a vibrating feeder (41) and a multi-layer inclined deflector (42). The raised deflector ribs (43) of the inclined deflector (42) disperse the ore axially on the magnetic roller, forming a uniform material layer with a thickness fluctuation ≤ ±1.5 mm. The vibration frequency of the inclined deflector (42) is 20 - 40 Hz, the period of the raised deflector ribs (43) is 1.5 - 2 times the average particle size of the ore, and the adjustable inclination angle range of the inclined deflector (42) is 45° - 60°; Step c. Monitor the surface temperature distribution of the magnetic roller in real time. When the local temperature exceeds the set threshold, the feedback controller (62) synchronously reduces the rotational speed of the magnetic roller and increases the excitation current frequency. The feedback controller (62) dynamically adjusts the rotational speed according to the temperature data so that the eddy current loss power satisfies the formula: ; It is necessary to pay attention to determining its critical maximum value; Step d. Detect the particle concentration in the feeding device (4) through a laser particle size counter (71); Step e. According to the detected concentration, transmit it to the control cabinet for data analysis, and then control the reduction motor (511) of the control switch to drive the bevel gear box (510) to drive the bidirectional lead screw (53) to rotate. The upper nut seats (59) on both sides of the bidirectional lead screw (53) move to both sides, driving the lower sliding blocks (58) to move outwards, driving the two groups of hinged baffle plates (51) to rotate, thereby opening the communication area with the feed pipe orifice (11), and thus controlling the feeding speed; Step f. Synchronously, an infrared sensor (61) is installed in the magnetic separation main frame (1) to detect the surface temperature of the sorting cylinder body (21), and the driving speed of the installation cylinder part (211) is controlled through the driving structure.

Images