A screening system and method for separating magnetic material in concrete aggregate

Abstract

This invention relates to the field of material sorting technology, and in particular to a screening system for separating magnetic substances from concrete aggregates; it includes a permanent magnet sorting device, an electromagnetic iron removal device, and a demagnetizing device; the permanent magnet sorting device includes a first conveyor belt and a permanent magnet drum disposed at the end of the first conveyor belt, separating ferromagnetic substances with larger particle size and stronger magnetism from the aggregates; the electromagnetic iron removal device includes a feed hopper and a magnetic roller transversely inserted into the feed hopper, which uses strong electromagnetic attraction to accurately capture tiny ferromagnetic particles attached to the surface of the aggregates and weakly magnetic substances wrapped by the material; the demagnetizing device includes a second conveyor belt and a demagnetizer disposed above the second conveyor belt, which generates a decaying magnetic field to eliminate residual magnetism in the aggregates; this significantly improves the thoroughness of ferromagnetic impurity separation, solves the problem of incomplete impurity removal in traditional single magnetic separation methods, and ensures the purity of the aggregates.

Description

Technical Field

[0001] This invention relates to the field of material sorting technology, and in particular to a screening system and method for separating magnetic substances from concrete aggregates. Background Technology

[0002] In some specialized engineering fields, a weak magnetic environment is often required for buildings, which places extremely stringent demands on the magnetic properties of the building materials. If ferromagnetic impurities are mixed into the materials, the building's ambient magnetic field will be significantly altered, thereby interfering with the magnetic field environment for precision instruments and ultimately affecting the accuracy and reliability of test results.

[0003] Concrete is a crucial raw material in engineering construction, with aggregates such as crushed stone, manufactured sand, or river sand accounting for approximately 70% to 85% of its mass. The magnetic properties of these aggregates directly affect the magnetic field environment of the building. Ferromagnetic substances are easily mixed into the aggregates during mining and processing, affecting their magnetic properties.

[0004] Currently, the main method used in engineering is to install permanent magnet adsorption devices on belt conveyors to adsorb magnetic impurities. While this can remove larger, more strongly magnetic ferromagnetic impurities from the aggregates, it is not thorough in separating tiny ferromagnetic particles attached to the surface of the raw materials and weakly magnetic substances encapsulated by the materials, resulting in residues. Furthermore, some aggregates are magnetized during the magnetic adsorption process of the permanent magnet adsorption device, carrying weak residual magnetism, making the aggregates unable to meet the requirements for non-magnetic technology.

[0005] Chinese patent CN119588650AA discloses a screening and residual magnetism detection equipment and its usage method for magnetic materials. The equipment uses a residual magnetism detection component to detect the magnetic properties of materials and screens out the materials in the non-conforming areas where magnetic properties are detected. When the distribution of magnetic materials is sparse, a large amount of materials without magnetic materials will be screened out, resulting in material waste. Since weak magnetic impurities have weak magnetic signals, there is also a risk of missed detection.

[0006] Therefore, a screening system and method for separating magnetic materials in concrete aggregates are provided, which can sort, remove, and eliminate weak residual magnetism in aggregates. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention provides a screening system and method for separating magnetic substances from concrete aggregates.

[0008] On one hand, this application provides a screening system for separating magnetic substances from concrete aggregates, comprising: Permanent magnet sorting device: includes a first conveyor belt and a permanent magnet roller disposed at the end of the first conveyor belt. The part of the first conveyor belt subjected to the magnetic attraction force generated by the permanent magnet roller is a strong magnetic adsorption area. The strong magnetic adsorption area is used to adsorb strong magnetic impurities in the aggregate. The aggregate with the strong magnetic impurities removed falls at the end of the first conveyor belt. An electromagnetic iron removal device includes a feed hopper with openings at the top and bottom, and a magnetic roller disposed below the feed hopper. The feed hopper is located below the end of the first conveyor belt. The magnetic roller is horizontally arranged and can rotate around its own axis. The upper part of the magnetic roller extends into the interior of the feed hopper, and the lower part extends out below the feed hopper. The surface of the magnetic roller has a weak magnetic adsorption area and a non-magnetic area along its rotation direction. The weak magnetic adsorption area is used to adsorb weakly magnetic impurities of the aggregate falling into the feed hopper, and the non-magnetic area is used to dislodge the weakly magnetic impurities. A first discharge channel is formed between the weak magnetic adsorption area and one side wall of the feed hopper for the aggregate to slide out after the removal of weakly magnetic impurities. The demagnetizing device includes a second conveyor belt and a demagnetizer disposed above the second conveyor belt. The feed end of the second conveyor belt is disposed below the feed hopper to receive aggregate discharged from the feed hopper after the weak magnetic impurities have been removed. The demagnetizer is used to generate a decaying magnetic field to eliminate residual magnetism in the aggregate.

[0009] In some embodiments of this application, the magnetic roller includes a cylindrical body that rotates about its own axis, an excitation component is biased inside the cylinder, the excitation component extends along the axial direction of the cylinder, and the excitation component does not rotate with the cylinder; The excitation component is located on one side wall near the feed hopper. The outer surface of the cylinder near the excitation component is the weak magnetic adsorption area, and the outer surface of the cylinder away from the excitation component is the non-magnetic area. After the weak magnetic impurities are adsorbed in the weak magnetic adsorption area, they fall off when the cylinder rotates to the non-magnetic area. The aggregate with the weak magnetic impurities removed slides out from the first discharge channel.

[0010] In some embodiments of this application, the feed hopper includes a guide section located above and a receiving section located below the guide section. The guide section is used to guide the aggregate to the weak magnetic adsorption zone, and the receiving section is used to install the cylinder. The gap between one side of the receiving section and the weak magnetic adsorption zone forms the first discharge channel.

[0011] In some embodiments of this application, the permanent magnet roller includes a fixed shaft, a permanent magnet fixed on the fixed shaft, and a protective sleeve sleeved on the outside of the permanent magnet; The protective sleeve rotates to guide the end of the first conveyor belt, ensuring that the end of the first conveyor belt runs smoothly.

[0012] In some embodiments of this application, the permanent magnet sorting device further includes a sorting cavity body, the sorting cavity body having the following internal components: A feeding channel is provided at the upper part of the sorting chamber body, and the fixed shaft is transversely inserted through the feeding channel; The second and third discharge channels are located below the sorting chamber body and are both connected to the feed channel. The third discharge channel is located near the end of the first conveyor belt and is used to receive the strongly magnetic impurities leaving the strongly magnetic adsorption area. The second discharge channel is used to receive the aggregate that has been de-magnetized and fallen from the end of the first conveyor belt.

[0013] In some embodiments of this application, the demagnetizer includes a housing and a demagnetizing assembly built into the housing, the housing spanning over the second conveyor belt, and the demagnetizing assembly generating a decaying magnetic field to eliminate residual magnetism in the aggregate passing under the second conveyor belt.

[0014] In some embodiments of this application, the system further includes a magnetic storage tank disposed below the feed hopper for receiving the strongly magnetic impurities sorted by the second discharge channel and the weakly magnetic impurities sorted and detached below the feed hopper.

[0015] In some embodiments of this application, the system further includes an aggregate cleaning device for removing dust adhering to the surface of the aggregate, and a material guiding component is provided between the aggregate cleaning device and the first conveyor belt, the material guiding component being used to guide the cleaned aggregate onto the first conveyor belt.

[0016] In some embodiments of this application, the first conveyor belt is connected to the first drive motor, and the second conveyor belt is connected to the second drive motor; The system also includes a controller connected to the first drive motor and the second drive motor, used to control the start and stop of the first drive motor and the second drive motor and their rotation speed, so as to control the start and stop of the first conveyor belt and the second conveyor belt and their conveying speed.

[0017] On the other hand, the present invention also provides a method for separating magnetic substances from concrete aggregates, comprising the following steps: Preliminary sorting: The aggregate is conveyed to the strong magnetic separation area, where the strong magnetic impurities in the aggregate are screened and separated by the magnetic force generated by the permanent magnet roller. Secondary sorting: The aggregate that has undergone the preliminary sorting step is conveyed to the weak magnetic separation area, where the weak magnetic impurities in the aggregate are adsorbed and separated by the magnetic force generated by the magnetic roller. Demagnetization process: The aggregate that has undergone the secondary sorting step is transported to the demagnetization area, and the residual magnetism in the aggregate is eliminated by the attenuated magnetic field generated by the demagnetizer, resulting in non-magnetic aggregate.

[0018] In some embodiments of this application, the magnetic field strength generated by the permanent magnet roller in the preliminary sorting step is 3000 Gs; In the secondary sorting step, the magnetic field strength generated by the magnetic roller is 5000 Gs; In the demagnetization process, the demagnetizing field strength of the demagnetizer is 500 Gs.

[0019] In some embodiments of this application, a cleaning step is included before the preliminary sorting step to clean the aggregate and remove impurities from the surface of the aggregate.

[0020] The screening system for separating magnetic substances in concrete aggregates based on the above technical solution uses a permanent magnet separator to separate ferromagnetic substances with larger particle size and stronger magnetism from the aggregates. The electromagnetic iron removal device uses strong electromagnetic attraction to accurately capture tiny ferromagnetic particles attached to the surface of the aggregates and weakly magnetic substances wrapped by the material. The dual screening of the permanent magnet separator and the electromagnetic iron removal device greatly improves the thoroughness of the separation of ferromagnetic impurities, solves the problem of incomplete impurity removal by the traditional single magnetic separation method, and ensures the purity of the aggregates. The permanent magnet sorting device, electromagnetic iron removal device, demagnetizing device, and first and second conveyor belts are integrated into a magnetic material sorting and separation system, which greatly improves the integration of each device and conveyor belt; there is no need to set up an additional independent magnetic separation unit and material transfer link, avoiding efficiency loss caused by repeated loading and unloading, reducing transfer energy consumption and production costs, and can adapt to the operation needs of large-scale concrete raw material production lines. The demagnetizing device specifically eliminates the weak residual magnetism generated in aggregates during the magnetic impurity sorting process, ensuring that the treated concrete aggregates meet the stringent requirements of special projects for non-magnetic materials. In addition to separating strongly magnetic impurities, the permanent magnet sorting device also has a guiding function in its protective sleeve. The second and third discharge channels in the sorting chamber body accurately divert strongly magnetic impurities and aggregates, ensuring the orderliness of the magnetic separation process and the stability of material conveying. The coordinated operation of each component realizes the automated operation of the entire demagnetization process, reduces manual intervention, avoids problems such as material accumulation and poor diversion in traditional demagnetization methods, and improves the consistency of demagnetization efficiency and processing quality. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the system for separating magnetic materials from concrete aggregates in an embodiment of the present invention; Figure 2 This is a schematic diagram of the permanent magnet sorting device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the permanent magnet drum according to an embodiment of the present invention; Figure 4 This is a schematic diagram showing the positional relationship between the sorting chamber body and the permanent magnet drum in an embodiment of the present invention; Figure 5 This is a cross-sectional view of the sorting chamber body and the permanent magnet drum according to an embodiment of the present invention; Figure 6 This is a schematic diagram showing the positional relationship between the sorting cavity body and the electromagnetic iron removal device in an embodiment of the present invention; Figure 7 This is a schematic diagram showing the positional relationship between the electromagnetic iron removal device and the demagnetizing device in an embodiment of the present invention; Figure 8 This is a schematic diagram showing the positional relationship between the cylinder and the excitation assembly in an embodiment of the present invention; Figure 9 This is a schematic diagram of the electromagnetic iron removal device according to an embodiment of the present invention; Figure 10 This is a schematic diagram showing the positional relationship between the cylinder, excitation assembly, and feed hopper in an embodiment of the present invention; Figure 11 This is a schematic diagram of the aggregate washing device according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the material guiding assembly and scraper according to an embodiment of the present invention.

[0022] In the picture: 10. Permanent magnet sorting device; 20. Electromagnetic iron removal device; 30. Demagnetizing device; 40. Magnetic storage tank; 50. Aggregate washing device; 60. Aggregate with strong magnetic impurities removed; 70. Controller; 11. First conveyor belt; 12. Permanent magnet drum; 13. First frame; 14. First drive motor; 15. Sorting chamber body; 16. Material guiding assembly; 17. Scraper; 121. Fixed shaft; 122. Permanent magnet; 123. Protective sleeve; 124. Bracket; 151. Feeding channel; 152. Second discharge channel; 1521. First guide wall; 153. Third discharge channel; 1531. Second guide wall; 161. Guide plate; 162. Baffle plate; 21. Feed hopper; 22. Magnetic roller; 23. Rotating shaft; 24. Third drive motor; 25. First discharge channel; 26. Support leg; 211. Feeding section; 212. Receiving section; 221. Cylinder; 222. Excitation assembly; 223. Weak magnetic adsorption zone; 224. Non-magnetic zone; 31. Second conveyor belt; 32. Demagnetizer; 33. Second drive motor; 321. Housing; 322. Cooling fan; 323. Indicator light; 51. Grinding wheel washing; 52. Water circulation tank; 521. Overflow outlet; 522. Sewage outlet; 61. Aggregate with weakly magnetic impurities removed; 62. Weakly magnetic impurities. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] like Figure 1As shown, an illustrative embodiment of the present invention provides a screening system for separating magnetic substances from concrete aggregates, including a permanent magnet sorting device 10 for sorting and separating strong magnetic impurities, an electromagnetic iron removal device 20 for adsorbing and separating weak magnetic impurities, and a demagnetizing device 30 for eliminating residual magnetism in the aggregates. The system seamlessly integrates the processes of separating strong magnetic impurities, removing weak magnetic impurities, and demagnetizing, and is suitable for the operational needs of large-scale concrete raw material production lines.

[0028] In some embodiments, such as Figure 2 As shown, the permanent magnet sorting device 10 includes a first conveyor belt 11 and a permanent magnet roller 12 disposed at the end of the first conveyor belt 11. Part of the structure of the first conveyor belt 11, which is subjected to the magnetic attraction generated by the permanent magnet roller 12, is a strong magnetic adsorption area. The strong magnetic adsorption area is close to the end of the first conveyor belt 11 and includes the upper and lower sides of the first conveyor belt 11. The aggregate enters the strong magnetic adsorption area under the conveying of the first conveyor belt 11. Strong magnetic impurities in the aggregate, such as ferromagnetic impurities with larger particle size and stronger magnetism, will be adsorbed onto the strong magnetic adsorption area. The aggregate with the strong magnetic impurities removed continues to move forward on the first conveyor belt 11 and falls off at the end of the first conveyor belt 11. The strong magnetic impurities are transferred from above the permanent magnet roller 12 to below on the first conveyor belt 11. As the distance from the permanent magnet roller 12 increases, the impurities fall off the first conveyor belt 11 after leaving the strong magnetic adsorption area.

[0029] like Figure 2 As shown, the first conveyor belt 11 is fixed on the first frame 13. A first drive motor 14 is provided on the first frame 13 near the beginning of the first conveyor belt 11. An active roller (not shown in the figure) is provided at the beginning of the first conveyor belt 11. The first drive motor 14 drives the first conveyor belt 11 to rotate by driving the active roller to rotate.

[0030] In some embodiments, the permanent magnet roller 12 includes a fixed shaft 121, a permanent magnet 122 passing through and fixed on the fixed shaft 121, and a protective sleeve 123 sleeved on the outside of the permanent magnet 122. The protective sleeve 123 rotates around the fixed shaft 121 under the drive of the first conveyor belt 11.

[0031] It should be noted that the permanent magnet drum 12 adopts a layered modular structure, such as... Figure 3As shown, the protective sleeve 123 is located on the outermost layer and is made of wear-resistant stainless steel. As the first protective barrier, the protective sleeve 123 effectively blocks the direct impact of external aggregates, thereby protecting the internal permanent magnets 122 from damage and extending the overall service life of the permanent magnet roller 12. A bracket 124 made of high-strength insulating material is also provided between the protective sleeve 123 and the permanent magnets 122. The bracket 124 can fix and support the permanent magnets 122. Multiple permanent magnets 122 are evenly arranged along the length of the fixed shaft 121 and fixed to the bracket 124 with bolts. This even arrangement design ensures that the spacing between each permanent magnet 122 is consistent, ensuring that the magnetic field strength generated in the length direction of the fixed shaft 121, i.e., the width direction of the first conveyor belt 11, is evenly and stably distributed, avoiding fluctuations in the separation effect of strongly magnetic impurities in the aggregates on the first conveyor belt 11 due to uneven magnetic field.

[0032] Both ends of the fixed shaft 121 are fixed to the first frame 13 at the end of the first conveyor belt 11. The protective sleeve 123, as the driven roller of the first conveyor belt 11, is set at its end. The first drive motor 14 drives the drive roller to rotate, which in turn drives the first conveyor belt to rotate, thereby causing the protective sleeve 123 to rotate around the fixed shaft 121. The rotation of the protective sleeve 123 guides the end of the first conveyor belt 11, ensuring that the end of the first conveyor belt 11 runs smoothly.

[0033] After the aggregate on the first conveyor belt 11 is transported to the strong magnetic adsorption area near the permanent magnet drum 12, the permanent magnet drum 12 generates an adsorption force on the strong magnetic impurities in the aggregate, causing the strong magnetic impurities to be temporarily adsorbed on the first conveyor belt 11. The strong magnetic impurities move forward with the first conveyor belt 11 and are transferred to the area below the permanent magnet drum 12. As the distance between them and the permanent magnet drum 12 gradually increases, the magnetic field adsorption force of the permanent magnet drum 12 on the strong magnetic impurities gradually weakens. When the strong magnetic impurities leave the strong magnetic adsorption area, they are detached from the first conveyor belt 11 under the action of gravity.

[0034] In some embodiments, the permanent magnet sorting device 10 further includes a sorting chamber body 15, with both ends of the sorting chamber body 15 fixed to the ends of the first frame 13. The sorting chamber body 15 has a feeding channel 151 and a second discharge channel 152 and a third discharge channel 153 disposed below the feeding channel 151. The second discharge channel 152 and the third discharge channel 153 are arranged back and forth along the aggregate forward direction.

[0035] Specifically, such as Figure 4As shown, the fixed shaft 121 is transversely inserted into the feed channel 151. A portion of the structure at the end of the first conveyor belt 11 is embedded within the feed channel 151. The second discharge channel 152 and the third discharge channel 153 are arranged sequentially. The second discharge channel 152 is the main discharge channel, located in front of the aggregate in the direction of forward movement and extending vertically downwards. Non-magnetic or low-magnetic aggregates, after initial screening by the permanent magnet roller 12, fall into the second discharge channel 152 at the end of the first conveyor belt 11 due to inertia and gravity. The third discharge channel 153 is located behind the second discharge channel 152, where the aggregate... When strongly magnetic impurities pass through the strongly magnetic adsorption zone affected by the magnetic attraction of the permanent magnet roller 12, they are adsorbed onto the first conveyor belt 11 and continue with the first conveyor belt 11 to the end position. The strongly magnetic impurities are still affected by the magnetic attraction of the permanent magnet roller 12 and will not fall off. They continue to move with the first conveyor belt 11 to the bottom of the permanent magnet roller 12. The distance between the strongly magnetic impurities and the permanent magnet roller 12 gradually increases, and the magnetic field force of the permanent magnet decreases. When they move to the top of the third discharge channel 153, the strongly magnetic impurities are separated from the first conveyor belt 11 and fall into the third discharge channel 153 under the action of gravity.

[0036] Furthermore, such as Figure 5 As shown, the second discharge channel 152 and the third discharge channel 153 are arranged alternately to achieve effective separation of strongly magnetic impurities from non-magnetic or low-magnetic aggregates. A first guide wall 1521 is located on one side of the second discharge channel 152 near the third discharge channel 153. The first guide wall 1521 is inclined in the direction of aggregate movement. The outlet opening of the third discharge channel 153 faces downwards and is directly opposite the electromagnetic iron removal device. The first guide wall 1521 receives non-magnetic or low-magnetic aggregates and guides them into the electromagnetic iron removal device. A second guide wall 1531 is located on one side of the third discharge channel 153 near the second discharge channel 152. The second guide wall 1531 is inclined away from the direction of aggregate movement. The outlet of the third discharge channel 153 is inclined backwards. A magnetic storage tank 40 is provided on the ground below the outlet of the third discharge channel 153. The second guide wall 1531 receives strongly magnetic impurities falling from the back of the first conveyor belt 11 and accurately guides them into the magnetic storage tank 40, thereby effectively separating the strongly magnetic impurities from the non-magnetic and low-magnetic aggregates. The non-magnetic and low-magnetic aggregates then enter the electromagnetic iron removal device 20.

[0037] In some embodiments, such as Figures 6-10As shown, the electromagnetic iron removal device 20 is used to separate weakly magnetic impurities from the aggregate. It includes a feed hopper 21 with openings at the top and bottom, and a magnetic roller 22 that is horizontally arranged below the feed hopper 21 and can rotate around its own axis. The upper part of the magnetic roller 22 extends into the interior of the feed hopper 21, and the lower part extends out below the feed hopper 21. A support leg 26 is provided below the feed hopper 21. The lower part of the support leg 26 is fixed to the feed end of the second conveyor belt 31 of the demagnetizing device 30. The upper opening of the feed hopper 21 corresponds to the discharge port of the second discharge channel 152.

[0038] In some embodiments, the magnetic roller 22 includes a cylindrical body 221 that rotates about its own axis. A horizontal rotating shaft 23 is fixed to the outer side of one end face of the cylinder 221. The rotating shaft 23 extends horizontally outward through the feed hopper 21 and is connected to a third drive motor 24. The third drive motor 24 drives the cylinder 221 to rotate through the rotating shaft 23. An excitation assembly 222 extending radially along the cylinder 221 is provided inside the cylinder 221. The length of the excitation assembly is the same as the length of the cylinder 221, so that the cylinder 221 can be subjected to the magnetic force generated by the excitation assembly 222 in the longitudinal direction. The excitation assembly 222 does not rotate with the cylinder 221 to maintain a stable magnetic field distribution.

[0039] In this embodiment, the cylinder 221 is made of wear-resistant and corrosion-resistant material and is used to wrap the excitation assembly 222, which plays a role in protection, dustproofing, waterproofing and auxiliary cooling, and can extend the service life of the excitation assembly 222.

[0040] In some embodiments, the excitation component 222 is the core component of the electromagnetic iron removal device 20, which directly determines its adsorption capacity. The excitation component 222 is composed of an excitation coil and an iron core. In this embodiment, in order to separate weakly magnetic impurities from the aggregate, the surface of the cylinder 221 is formed along its rotation direction to form a weakly magnetic adsorption area 223 and a non-magnetic area 224 that can adsorb weakly magnetic impurities. The weakly magnetic adsorption area 223 can adsorb weakly magnetic impurities in the aggregate, and the weakly magnetic impurities fall off in the non-magnetic area. The excitation component 222 is biased inside the cylinder 221, and the magnetic field it generates can only affect part of the structure of the cylinder 221 to form a weakly magnetic adsorption area. The other part is not affected by the magnetic field and is the non-magnetic area.

[0041] Specifically, the excitation assembly 222 is disposed on one side of the magnetic roller 22 near the second conveyor belt 31 of the demagnetizing device 30. Figure 8 , Figure 10The image shows the excitation assembly 222 located on the right side of the cylinder 221. The longitudinal cross-section of the excitation assembly 222 is semi-circular, meaning the cross-section of the iron core is semi-circular. The excitation coil is wound around the iron core, which is made of a high-permeability magnetic material. When the excitation coil is energized, it generates a strong electromagnetic attraction. The portion of the cylinder 221 closest to the excitation assembly 222 is a weak magnetic adsorption zone due to the magnetic force of the excitation assembly 222, used to adsorb weakly magnetic impurities in the aggregate. The portion of the magnetic roller 22 furthest from the excitation coil is a non-magnetic zone. Figure 8 The right side of the magnetic roller 22 is a weak magnetic adsorption area, and the left side is a non-magnetic area.

[0042] In some embodiments, such as Figure 10 As shown, the feed hopper 21 includes a guide section 211 located above and a receiving section 212 located below the guide section 211. The guide section 211 has a rectangular cross-section and a funnel-shaped structure that is wider at the top and narrower at the bottom. The guide section 211 gathers the aggregate into the weak magnetic adsorption area 223. The receiving section 212 is a cuboid cavity structure formed by two long side walls and two short side walls. The cylinder 221 is set inside the receiving section 212. The length of the cylinder 221 is adapted to the length of the receiving section 212. The diameter of the cylinder 221 is smaller than the width of the receiving section 212, so that a first channel for the aggregate to pass through is formed between the cylinder 221 and a long side wall of the receiving section 212.

[0043] from Figure 10 As can be seen, the left side of the cylinder 221, i.e., the non-magnetic zone 224, is in contact with the left long sidewall of the receiving part 212, and there is no gap between them. Therefore, even if some aggregate falls into the non-magnetic zone 224, it will be blocked, avoiding the phenomenon that some weakly magnetic impurities will directly enter the demagnetizing device 30 without passing through the weak magnetic separation zone 223 to adsorb the weakly magnetic impurities. There is a gap between the right side of the cylinder 221, i.e., the weak magnetic separation zone 223, and the right long sidewall of the receiving part 212. This gap is the first discharge channel 25 for the aggregate to pass through in a directional manner. The difference between the diameter of the cylinder 221 and the width of the receiving part 212 is related to the particle size of the aggregate. The difference between the two should be slightly larger than the particle size of the aggregate, so as to ensure the separation purity of weakly magnetic impurities in the aggregate while allowing the aggregate to pass through smoothly.

[0044] like Figure 8 As shown, the aggregate 60 from the second discharge channel 152, after the removal of strong magnetic impurities, is gathered in the weak magnetic adsorption zone 223 under the action of the guide section 211. As the cylinder 221 rotates counterclockwise, the aggregate enters the first discharge channel 25. The weak magnetic impurities 62 in the aggregate are adsorbed on the weak magnetic adsorption zone 223. When the cylinder 221 rotates and leaves the first discharge channel 25 to transfer to the non-magnetic zone 224, they fall off under the action of gravity and the inertial force generated by the rotation of the cylinder 221. The aggregate 61 after the removal of weak magnetic impurities slides down from the end of the first discharge channel and is discharged under the action of gravity.

[0045] After the weakly magnetic impurity 62 falls off in the non-magnetic area, it also falls into the magnetic storage tank 40. A discharge door (not shown in the figure) is provided on one side of the magnetic storage tank 40 to facilitate the operator to clean and recycle the magnetic material regularly and avoid secondary pollution of the magnetic material.

[0046] In some embodiments, the demagnetizing device 30 demagnetizes the weak residual magnetism carried by the material. The demagnetizing device 30 includes a second conveyor belt 31 and a demagnetizer 32 disposed above the second conveyor belt 31. One end of the second conveyor belt 31 is disposed near the lower part of the first discharge channel 25 on the feed hopper 21 to receive the aggregate with weak magnetic impurities removed that falls from the first discharge channel 25. The demagnetizer 32 generates a decaying magnetic field to eliminate the residual magnetism in the aggregate.

[0047] In some embodiments, such as Figure 11 As shown, the demagnetizer 32 includes a housing 321 and a demagnetizing assembly (not shown) built into the housing. The demagnetizing assembly includes a demagnetizing excitation coil and a silicon steel sheet core. The housing 321 spans above the second conveyor belt 31. In this embodiment, the housing 321 has an inverted U-shaped structure and is made of high-strength alloy material, which provides physical protection for the internal excitation coil and silicon steel sheet core. Its inner wall is also fitted with a permalloy magnetic shielding layer, which can effectively block the leakage of the magnetic field generated during the demagnetization process, avoid interfering with the normal operation of surrounding instruments and equipment, and at the same time ensure the personal safety of the operator.

[0048] like Figure 1 As shown, a cooling fan 322 and an indicator light 323 are installed on the outer casing 321. The cooling fan 322 is linked to the temperature control system of the demagnetizer 32. When the internal temperature of the demagnetizer 32 exceeds the set threshold, the cooling fan 322 will start automatically to dissipate heat in time and prevent the equipment from overheating and being damaged. The indicator light 323 is used to display the working status of the demagnetizer 32. A green light indicates that the equipment is working normally, and a red light indicates that the equipment is faulty. When the indicator light 323 is lit to indicate the working status, magnetic objects should not be placed around the second conveyor belt 31 to avoid the interaction of magnetic fields affecting the demagnetization effect or causing safety hazards.

[0049] In some embodiments, the system further includes an aggregate washing device 50 for removing dust adhering to the aggregate surface. The aggregate washing device 50 adopts a dual-wheel linkage design, with two washing wheels 51 arranged symmetrically side by side. This structure allows the sand and gravel to be lifted and repeatedly washed between the wheel buckets of the two washing wheels 51, effectively removing mud, dust, and adhering impurities from the surface of the sand and gravel, significantly improving the purity and quality of the finished sand. Each washing wheel 51 is driven by a fourth drive motor 53 and a gear and chain transmission structure, ensuring that the two washing wheels 51 rotate synchronously and in the same direction. To ensure a stable and controllable cleaning process, a water circulation tank 52 is installed below the sanding wheel 51. The water circulation tank 52 is used to store cleaning water. An overflow port 521 is opened on one side wall at a corresponding height. When the water level in the water circulation tank 52 is higher than the overflow port 521, the excess water is discharged through the overflow port 521. A drain port 522 is provided at the bottom of the water circulation tank 52 to periodically discharge the impurities that have settled in the tank. Through the cooperation of the overflow port 521 and the drain port 522, the cleaning water can be recycled and the tank can be cleaned regularly, reducing water consumption and operation and maintenance costs. The aggregate first enters the water circulation tank 52 where the first washing wheel 51 is located. Driven by the rotation of the wheel bucket of the first washing wheel 51, the aggregate is stirred, tumbled and ground against each other, initially separating surface impurities. Then the aggregate is picked up by the wheel bucket of the first washing wheel 51 and conveyed forward to the position of the second washing wheel 51. After being stirred, ground and washed by the second washing wheel 51, residual fine impurities are removed. Finally, the wheel bucket of the second washing wheel 51 completes the lifting and discharge of the aggregate.

[0050] like Figure 12 As shown, a guide assembly 16 is provided between the aggregate washing device 50 and the first conveyor belt 11. After the aggregate washing device 50 has finished washing, the material is guided onto the first conveyor belt 11 through the guide assembly 16. The guide assembly 16 includes a guide plate 161 and two baffle plates 162. The guide plate 161 connects the outlet of the aggregate washing device 50 to one side of the first conveyor belt 11. The aggregate washed by the aggregate washing device 50 is guided onto the feed end of the first conveyor belt 11 through the guide plate 161. One of the baffle plates... A baffle plate 162 is set on the opposite side of the guide plate 161, and another baffle plate 162 is set at the end of the first conveyor belt 11. The baffle plate 162 can prevent the aggregate from falling off the first conveyor belt 11. A scraper 17 is also set on the first conveyor belt 11 behind the guide assembly 16. The scraper 17 is an inclined plate with a certain distance between its bottom edge and the first conveyor belt 11. The scraper 17 is used to comb the aggregate to ensure that the aggregate is evenly distributed on the first conveyor belt 11 and to avoid the magnetic separation effect being affected by the accumulation of materials.

[0051] In some embodiments, the first conveyor belt 11 is connected to the first drive motor 14, and the second conveyor belt 31 is connected to the second drive motor 33. The system also includes a controller 70, which is fixed on the frame of the first conveyor belt 11 and connected to the first drive motor 14, the second drive motor 33, and the third drive motor 24. The controller 70 is used to control the start and stop of the first drive motor 14, the second drive motor 33, and the third drive motor 24, as well as their rotation speed, to control the start and stop of the first conveyor belt 11 and the second conveyor belt 31, as well as their conveying speed, and the start and stop of the magnetic roller 22, so as to ensure the sorting effect and demagnetization effect of strong magnetic impurities and weak magnetic impurities in the aggregate.

[0052] On the other hand, the present invention provides a method for separating magnetic substances from concrete aggregates, comprising the following steps: S1 Preliminary sorting: The aggregate is conveyed to the feed end of the first conveyor belt 11. The first drive motor 14 is started to drive the first conveyor belt 11 to rotate. When the aggregate is transferred to the strong magnetic separation area affected by the magnetic force of the permanent magnet drum 12, the strong magnetic impurities with larger particle size and stronger magnetism in the aggregate are adsorbed on the first conveyor belt 11 and continue to move forward with the first conveyor belt 11. When it moves to the end of the first conveyor belt 11, the strong magnetic impurities are still adsorbed on the first conveyor belt 11 due to the magnetic force generated by the permanent magnet roller 12. The aggregate with the strong magnetic impurities removed slides forward into the second discharge channel 152 located in front of the sorting chamber body 15 due to inertia at the end of the first conveyor belt 11. The strongly magnetic impurities continue to move with the first conveyor belt 11 to the opposite side of the first conveyor belt 11, and the distance between them and the permanent magnet roller 12 becomes farther and farther. The magnetic attraction force on the strongly magnetic impurities becomes weaker and weaker. When the gravity is greater than that of the strongly magnetic impurities, the strongly magnetic impurities fall off from the opposite side of the first conveyor belt 11 and fall into the third discharge channel 153. They are then introduced into the magnetic storage tank 40 through the third discharge channel 153 for collection, thus completing the screening and separation of the strongly magnetic impurities from the aggregate. It should be noted that in order to remove the mud, dust and organic impurities attached to the surface of the aggregate and to prevent these impurities from encapsulating the aggregate particles or magnetic impurities and affecting the subsequent screening and separation of strongly magnetic and weakly magnetic materials, the aggregate is first cleaned in step S0 before step S1. S0 Cleaning Steps: The aggregate is poured into the aggregate cleaning device 50. The aggregate first enters the water circulation tank 52 where the first washing wheel 51 is located. Driven by the rotation of the wheel bucket of the first washing wheel 51, the aggregate is stirred, rolled and ground against each other, initially separating surface impurities. Then the aggregate is picked up by the wheel bucket of the first washing wheel 51 and conveyed forward to the position of the second washing wheel 51. After being stirred, ground and rinsed by the second washing wheel 51, residual fine impurities are removed. Finally, the wheel bucket of the second washing wheel 51 completes the lifting and discharge of the aggregate.

[0053] After being cleaned by the aggregate washing device 50, the aggregate is guided by the material guiding component 16 and enters the feed end of the first conveyor belt 11. Then, after being combed by the scraper 17, the aggregate is evenly distributed on the first conveyor belt 11.

[0054] S2 Secondary Sorting: In step S1, the aggregate 60 that has had strong magnetic impurities removed from the second discharge channel 152 falls into the feed hopper 21 near the weak magnetic separation zone 223. The third drive motor 24 drives the cylinder 221 of the magnetic roller 22 to rotate counterclockwise. The rotation of the cylinder 221 guides the aggregate into the first discharge channel 25. As the cylinder 221 rotates, weak magnetic impurities are adsorbed onto the weak magnetic separation zone 223. The cylinder 221 drives the remaining aggregate to move within the first discharge channel 25. When the remaining aggregate moves... When it reaches the end of the first discharge channel 25, it slides down under the action of gravity. Since the end of the first discharge channel 25 is still a weak magnetic adsorption area, the weak magnetic impurities are still adsorbed on the cylinder 221 here. The cylinder 221 continues to rotate. When the weak magnetic impurities move to the non-magnetic area 224, under the action of gravity and the inertial force generated by the rotation of the cylinder 221 on the weak magnetic impurities, the weak magnetic impurities are separated from the cylinder 221 and fall into the magnetic storage tank 40 for collection, thus completing the screening and separation of weak magnetic impurities from the aggregate. S3 Demagnetization process: In step S2, the aggregate that has been removed from the weak magnetic impurities and has fallen from the first discharge channel 25 falls into the feed end of the second conveyor belt 31. The second drive motor 33 starts and drives the second conveyor belt 31 to rotate. When the aggregate is conveyed to the bottom of the demagnetizer 32, the attenuated magnetic field generated by the demagnetizer 32 eliminates the residual magnetism in the aggregate, resulting in non-magnetic aggregate.

[0055] In some embodiments, in step S1, in order to better screen and separate strongly magnetic impurities, the magnetic field strength generated by the permanent magnet drum 12 is 3000 Gs. In step S2, in order to improve the accuracy of screening and separating weakly magnetic impurities in the aggregate, the magnetic field strength generated by the magnetic roller 22 is 5000 Gs. In step S3, since the strong magnetic impurities in the aggregate were removed in step S1 and the weak magnetic substances were removed in step S2, the residual magnetism in the aggregate is small. The demagnetizing field strength of the demagnetizer 32 is 500 Gs. The residual magnetic field strength of the aggregate after demagnetization by the demagnetizer 32 is less than 1 nT. After magnetization by 40 mT, the change in residual magnetism is less than 7 nT.

[0056] The system for separating magnetic substances in concrete aggregates based on the above technical solution uses a permanent magnet separator to separate ferromagnetic substances with larger particle size and stronger magnetism from the aggregates. The electromagnetic iron removal device uses strong electromagnetic attraction to accurately capture tiny ferromagnetic particles attached to the surface of the aggregates and weakly magnetic substances wrapped by the material. The dual screening of the permanent magnet separator and the electromagnetic iron removal device greatly improves the thoroughness of the separation of ferromagnetic impurities, solves the problem of incomplete impurity removal by the traditional single magnetic separation method, and ensures the purity of the aggregates. The permanent magnet sorting device, electromagnetic iron removal device, demagnetizing device, and first and second conveyor belts are integrated into a magnetic material sorting and separation system, which greatly improves the integration of each device and conveyor belt; there is no need to set up an additional independent magnetic separation unit and material transfer link, avoiding efficiency loss caused by repeated loading and unloading, reducing transfer energy consumption and production costs, and can adapt to the operation needs of large-scale concrete raw material production lines. The demagnetizing device specifically eliminates the weak residual magnetism generated in aggregates during the magnetic impurity sorting process, ensuring that the treated concrete aggregates meet the stringent requirements of special projects for non-magnetic materials. In addition to separating strongly magnetic impurities, the permanent magnet sorting device also has a guiding function in its protective sleeve. The second and third discharge channels in the sorting chamber body accurately divert strongly magnetic impurities and aggregates, ensuring the orderliness of the magnetic separation process and the stability of material conveying. The coordinated operation of each component realizes the automated operation of the entire demagnetization process, reduces manual intervention, avoids problems such as material accumulation and poor diversion in traditional demagnetization methods, and improves the consistency of demagnetization efficiency and processing quality.

[0057] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A screening system for separating magnetic substances from concrete aggregates, characterized in that, include: Permanent magnet sorting device: includes a first conveyor belt and a permanent magnet roller disposed at the end of the first conveyor belt. The part of the first conveyor belt subjected to the magnetic attraction force generated by the permanent magnet roller is a strong magnetic adsorption area, which is used to adsorb strong magnetic impurities in the aggregate. An electromagnetic iron removal device includes a feed hopper with openings at the top and bottom, and a magnetic roller disposed below the feed hopper. The feed hopper is located below the end of the first conveyor belt. The magnetic roller is horizontally arranged and can rotate around its own axis. The upper part of the magnetic roller extends into the interior of the feed hopper, and the lower part extends out below the feed hopper. The surface of the magnetic roller has a weak magnetic adsorption area and a non-magnetic area along its rotation direction. The weak magnetic adsorption area is used to adsorb weakly magnetic impurities of the aggregate falling into the feed hopper, and the non-magnetic area is used to dislodge the weakly magnetic impurities. A first discharge channel is formed between the weak magnetic adsorption area and one side wall of the feed hopper for the aggregate to slide out after the removal of weakly magnetic impurities. The demagnetizing device includes a second conveyor belt and a demagnetizer disposed above the second conveyor belt. The feed end of the second conveyor belt is disposed below the feed hopper to receive aggregate discharged from the feed hopper after the weak magnetic impurities have been removed. The demagnetizer is used to generate a decaying magnetic field to eliminate residual magnetism in the aggregate.

2. The screening system for separating magnetic substances from concrete aggregates according to claim 1, characterized in that, The magnetic roller includes a cylindrical body that rotates about its own axis. An excitation component is disposed inside the cylinder and extends along the axial direction of the cylinder. The excitation component does not rotate with the cylinder. The excitation component is located on one side wall near the feed hopper. The outer surface of the cylinder near the excitation component is the weak magnetic adsorption area, and the outer surface of the cylinder away from the excitation component is the non-magnetic area.

3. The screening system for separating magnetic substances from concrete aggregates according to claim 2, characterized in that, The feed hopper includes a guide section located above and a receiving section located below the guide section. The guide section is used to guide the aggregate to the weak magnetic adsorption zone, and the receiving section is used to install the cylinder. The gap between one side of the receiving section and the weak magnetic adsorption zone forms the first discharge channel.

4. The screening system for separating magnetic substances from concrete aggregates according to claim 1, characterized in that, The permanent magnet roller includes a fixed shaft, a permanent magnet fixed on the fixed shaft, and a protective sleeve sleeved on the outside of the permanent magnet. The protective sleeve rotates to guide the end of the first conveyor belt.

5. The screening system for separating magnetic substances from concrete aggregates according to claim 4, characterized in that, The permanent magnet sorting device further includes a sorting cavity body, the sorting cavity body having the following internal structure: A feeding channel is provided at the upper part of the sorting chamber body, and the fixed shaft is transversely inserted through the feeding channel; The second and third discharge channels are located below the sorting chamber body and are both connected to the feed channel. The third discharge channel is located near the end of the first conveyor belt and is used to receive the strongly magnetic impurities leaving the strongly magnetic adsorption area. The second discharge channel is used to receive the aggregate that has been de-magnetized and fallen from the end of the first conveyor belt.

6. The screening system for separating magnetic substances from concrete aggregates according to claim 1, characterized in that, The demagnetizing machine includes a housing and a demagnetizing assembly built into the housing. The housing spans over the second conveyor belt. The demagnetizing assembly is used to generate a decaying magnetic field to eliminate residual magnetism in the aggregate passing under the second conveyor belt.

7. The screening system for separating magnetic substances from concrete aggregates according to claim 1, characterized in that, The system also includes an aggregate cleaning device for removing dust adhering to the surface of the aggregate. A material guiding component is provided between the aggregate cleaning device and the first conveyor belt. The material guiding component is used to guide the cleaned aggregate onto the first conveyor belt.

8. A method for separating magnetic substances from concrete aggregates, using the screening system for separating magnetic substances from concrete aggregates as described in any one of claims 1-7, characterized in that, Includes the following steps: Preliminary sorting: The aggregate is conveyed to the strong magnetic separation area, where the strong magnetic impurities in the aggregate are screened and separated by the magnetic force generated by the permanent magnet roller, and the aggregate with the strong magnetic impurities removed is obtained. Secondary sorting: The aggregate that has undergone the preliminary sorting step is conveyed to the weak magnetic separation area, where the weak magnetic impurities in the aggregate are adsorbed and separated by the magnetic force generated by the magnetic roller. Demagnetization process: The aggregate that has undergone the secondary sorting step is transported to the demagnetization area, and the residual magnetism in the aggregate is eliminated by the attenuated magnetic field generated by the demagnetizer, resulting in non-magnetic aggregate.

9. The method for separating magnetic substances from concrete aggregates according to claim 8, characterized in that, In the preliminary sorting step, the magnetic field strength generated by the permanent magnet roller is 3000 Gs; In the secondary sorting step, the magnetic field strength generated by the magnetic roller is 5000 Gs; In the demagnetization process, the demagnetizing field strength of the demagnetizer is 500 Gs.

10. The method for separating magnetic substances from concrete aggregates according to claim 8, characterized in that, Before the preliminary sorting step, a cleaning step is also included to clean the aggregate to remove impurities from the surface of the aggregate.

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