Metal foreign matter removing method and system for coal conveying belt

Abstract

The invention relates to the technical field of large bulk material belt conveyor conveying, in particular to a metal foreign matter removing method and system for a coal conveying belt, and the system comprises five stages of sorting units which are sequentially arranged in the conveying direction of the coal conveying belt and used for conducting five-stage sorting on coal on the coal conveying belt so as to grab large metal foreign matter and remove magnetic metal foreign matter through magnetic separation. And non-magnetic metal foreign matters are subjected to reduction treatment through shunting and screening, and non-metal foreign matters are grabbed for the second time. A cascade type sorting method is formed through the five stages of sorting units, large metal foreign matter is detected, grabbed and removed in the first-stage sorting process, magnetic metal foreign matter is removed in the second-stage sorting process through detection and magnetic separation, and non-magnetic foreign matter is subjected to step-by-step reduction treatment through shunting and screening in the third-stage sorting process and the fourth-stage sorting process, so that the sorting burden is reduced, and the sorting efficiency is improved. And the non-magnetic metal foreign matters are detected, grabbed and removed again during five-stage sorting, so that the removal rate of the magnetic attraction and the non-magnetic metal foreign matters is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of large bulk material conveyor belt technology, specifically to a method and system for removing metal foreign objects from coal conveyor belts. Background Technology

[0002] Large bulk material belt conveyors are key equipment for material handling in modern industry, especially in the field of coal transportation. However, metallic foreign objects, including magnetic and non-magnetic metals, are often mixed into the coal. These foreign objects are one of the main hidden dangers leading to severe wear of downstream coal mills, belt damage, and even system shutdown, resulting in huge maintenance costs and production losses.

[0003] Currently, the commonly used electromagnetic iron removal method removes metallic foreign objects from coal. However, its working principle typically only adsorbs ferromagnetic metals, and it is ineffective against common non-magnetic metals. Furthermore, electromagnetic iron removal is greatly affected by the thickness of the coal layer and the conveying speed, making it prone to missed detections. Therefore, it is difficult to meet the reliable removal requirements for various types of metallic foreign objects under complex working conditions.

[0004] Therefore, the existing electromagnetic iron removal method used in coal conveying processes can only adsorb ferromagnetic metal foreign objects due to its electromagnetic effect, and it is difficult to adsorb, detect and remove non-magnetic metal foreign objects, making it difficult to meet the requirements for removing various metal foreign objects mixed in coal. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for removing metallic foreign objects from coal conveyor belts, in order to solve the technical problem that the existing technology can only adsorb ferromagnetic metallic foreign objects due to its electromagnetic effect, and it is difficult to adsorb, detect and remove non-magnetic metallic foreign objects, thus making it difficult to meet the requirements for removing various metallic foreign objects mixed in coal.

[0006] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: A method for removing metallic foreign objects from a coal conveyor belt includes the following steps: Primary sorting: Upstream of the coal conveyor belt, large metal foreign objects are detected by ultrasonic detection, and a primary robotic arm and camera are used to locate and grab them, removing large magnetic and non-magnetic metal foreign objects from the coal. Secondary sorting: Downstream of the coal conveyor belt, metal detection is performed on the coal after primary sorting. When a metal foreign object is detected, this section of coal is pushed off the coal conveyor belt onto the secondary belt. The permanent magnet roller of the secondary belt adsorbs the magnetic metal foreign object and removes it from the bottom, while the coal is discharged from the discharge end. Through a combination of magnetic separation and diversion, the magnetic metal foreign object is separated from the coal and non-magnetic metal foreign objects. Three-stage sorting: The three-stage conveyor belt receives the coal discharged from the discharge end of the two-stage conveyor belt. Metal detection is performed on the coal after the two-stage sorting. When a metal foreign object is detected, the coal containing non-magnetic metal foreign objects is conveyed to the drum screen for screening through the diversion mechanism. Coal smaller than 10mm is screened and discharged onto the coal conveyor belt, while coal larger than 10mm is discharged outside the coal conveyor belt. When no metal foreign object is detected, the coal is directly discharged onto the coal conveyor belt through the diversion mechanism. Fourth-level sorting: The fourth-level belt receives coal material larger than 10mm that was rejected in the third-level sorting and performs metal detection on the coal material conveyed on the fourth-level belt. When a non-magnetic metal foreign object is detected, a pusher is used to push this section of coal material off the fourth-level belt to remove it; when no non-magnetic metal foreign object is detected, the coal material is directly dropped onto the conveyor belt. Five-stage sorting: The sorting box is used to collect the coal and non-metallic foreign objects that have been rejected by the four-stage sorting and to detect metal. Then, the first-stage robotic arm and camera are used to locate and grab the remaining non-magnetic metal foreign objects. The coal with the non-magnetic metal foreign objects removed is dropped into the collection box and then transported to the coal conveyor belt by the screw conveyor. The coal conveyor belt intermittently transports coal according to a set conveying distance, and the coal conveyor belt restarts after the first and second sorting processes are completed.

[0007] As a preferred embodiment of the present invention, in the four-stage sorting step, there are at least two pushers, each pusher corresponding to an ultrasonic detector, and the pushers and the ultrasonic detectors are arranged sequentially along the conveying direction of the four-stage belt. Each ultrasonic detector is located on the material receiving side corresponding to the pusher, so as to form redundant detection of metallic foreign objects in the coal.

[0008] To address the aforementioned technical problems, the present invention further provides the following technical solution: A foreign object removal system employing the above-mentioned method for removing metal foreign objects from coal conveyor belts includes: The coal conveyor belt is provided with a first-level sorting unit, a second-level sorting unit, a third-level sorting unit, a fourth-level sorting unit and a fifth-level sorting unit in sequence along the conveying direction of the coal conveyor belt; The first-level sorting unit is used for first-level sorting, the second-level sorting unit is used for second-level sorting, the third-level sorting unit is used for third-level sorting, the fourth-level sorting unit is used for fourth-level sorting, and the fifth-level sorting unit is used for fifth-level sorting.

[0009] As a preferred embodiment of the present invention, the primary sorting unit includes: A large metal foreign object recovery box is installed on one side of the coal conveyor belt; A primary robotic arm is positioned upstream of the conveyor belt and on the same side as the large metal foreign object recovery box. It has a primary robotic hand and a primary industrial camera. The primary robotic arm is configured to control the primary robotic hand to grab large metal foreign objects in the coal material based on the image information from the primary industrial camera. A primary ultrasonic detector is installed on the coal conveyor belt, with the detection end of the primary ultrasonic detector facing the feed end surface of the coal conveyor belt, and is used to detect metallic foreign objects in the coal. The coal conveyor belt intermittently transports coal through the first-stage ultrasonic detector to form a coal section. When the first-stage ultrasonic detector detects a metallic foreign object, the first-stage robotic arm uses the first-stage robotic hand and the first-stage industrial camera to grab it in this coal section and remove large magnetic and non-magnetic metallic foreign objects from the coal to the large metallic foreign object recovery box.

[0010] As a preferred embodiment of the present invention, the secondary sorting unit includes: A magnetic metal recycling box is located below one side of the coal conveyor belt; A high-speed coal plow is disposed in the middle of the coal conveyor belt. The high-speed coal plow is configured to move horizontally on the coal conveyor belt in a direction perpendicular to the conveying direction in order to push a section of coal off the side of the coal conveyor belt. A secondary screw conveyor is installed on one side of the coal conveying belt and opposite to the high-speed coal plow. The feed inlet of the secondary screw conveyor is lower than the side of the coal conveying belt to catch the coal pushed down by the high-speed coal plow. A secondary belt is located below the secondary screw conveyor. One end of the belt is used to collect the coal discharged from the outlet of the secondary screw conveyor. The secondary belt has a permanent magnet drum away from the outlet of the secondary screw conveyor. The permanent magnet drum is configured to attract magnetic metal foreign objects to the surface of the secondary belt so that they rotate to the bottom of the permanent magnet drum and fall into the magnetic metal recycling box away from the permanent magnet drum. A secondary ultrasonic detector is installed on the coal conveyor belt and located downstream of the primary ultrasonic detector. The detection end of the secondary ultrasonic detector faces the surface of the coal conveyor belt and is used to detect metallic foreign objects in the coal. A primary sorting area is formed between the secondary ultrasonic detector and the primary ultrasonic detector. Wherein, the first-level robotic arm controls the first-level robotic hand to move within a range that covers the first-level sorting area, and the distance between the high-speed coal plow and the second-level ultrasonic detector is an integer multiple of the length of the first-level sorting area; Furthermore, the conveying distance of each intermittent conveying operation of the coal conveyor belt is equal to the length of the primary sorting area; Furthermore, when the high-speed coal plow detects a metallic foreign object in the coal section by the secondary ultrasonic detector and moves to the working area of ​​the high-speed coal plow, the high-speed coal plow pushes the coal off the coal conveyor belt. Furthermore, if the secondary ultrasonic detector does not detect any metallic foreign objects, or if the secondary ultrasonic detector detects metallic foreign objects and the coal material in this section is transported to the working area of ​​the high-speed coal plow, the high-speed coal plow will not work, so that the coal conveyor belt can transport coal downstream.

[0011] As a preferred embodiment of the present invention, the three-level sorting unit includes: The third-stage conveyor belt has its feed end located below the discharge end of the second-stage conveyor belt to catch the coal falling from the second-stage conveyor belt, and its discharge end is located above the coal conveyor belt. The irregularly shaped tee has its inlet located below the outlet end of the three-stage conveyor belt, and has a first material discharge channel and a second material discharge channel inside, as well as a tee baffle located at the inlet. The tee baffle is configured to be driven by a motor located outside the irregularly shaped tee to adjust the blocking direction, so as to selectively block the first material discharge channel or the second material discharge channel. The outlet of the first material discharge channel is located above the coal conveyor belt, and is used to directly discharge coal onto the coal conveyor belt. A drum screen is used to screen the coal inside it. Its inlet is connected to the outlet of the second discharge channel to receive the coal discharged from the second discharge channel. The drum screen has a fine material outlet and a coarse material outlet. The fine material outlet is located above the coal conveyor belt and is used to discharge the coal directly onto the coal conveyor belt. The coarse material outlet is connected to the four-stage sorting unit. A three-stage ultrasonic detector is installed on the three-stage conveyor belt, with the detection end of the three-stage ultrasonic detector facing the surface of the three-stage conveyor belt, for detecting metallic foreign objects in the coal. Wherein, when the third-level ultrasonic detector is close to the material drop end of the third-level belt, when the third-level ultrasonic detector detects a metal foreign object, the three-way baffle blocks the first material drop channel, so that this section of coal is discharged from the second material drop channel into the drum screen for screening. Furthermore, when the three-stage ultrasonic detector does not detect any metallic foreign objects, the three-way baffle blocks the second material discharge channel so that this section of coal is directly discharged from the first material discharge channel onto the coal conveyor belt.

[0012] As a preferred embodiment of the present invention, the four-level sorting unit includes: The fourth-stage conveyor belt has its feed end located below the coarse material outlet to collect the coal discharged from the coarse material outlet, and the fourth-stage conveyor belt is located above the coal conveyor belt. A pusher mechanism is provided on one side of the fourth-level belt, and has a first pusher and a second pusher. The first pusher and the second pusher are arranged sequentially along the conveying direction of the fourth-level belt, and the first pusher and the second pusher are configured to push the coal on the fourth-level belt off in a direction perpendicular to the fourth-level belt, and the first pusher and the second pusher work independently. A coal chute is located on the other side of the fourth-stage conveyor belt and opposite to the pusher mechanism. It is used to guide the coal pushed down by the first and second pushers to be discharged in a directional manner, and the lower end of the coal chute is connected to the fifth-stage sorting unit. The fourth-level ultrasonic detector is provided on the upstream side of both the first pusher and the second pusher, and the first pusher and the second pusher are configured to operate according to the detection signal of the fourth-level ultrasonic detector on the upstream side. When the first level four ultrasonic detector detects a metallic foreign object, the first pusher pushes the section of coal to the coal chute. When the first level four ultrasonic detector does not detect a metallic foreign object, but the second level four ultrasonic detector detects a metallic foreign object, the second pusher pushes the section of coal to the coal chute. Furthermore, when neither of the two aforementioned level-four ultrasonic detectors detects a metallic foreign object, the level-four conveyor belt directly discharges the coal onto the coal conveyor belt.

[0013] As a preferred embodiment of the present invention, the five-level sorting unit includes: A five-stage sorting box is located on one side of the coal conveyor belt. The five-stage sorting box has a sorting bin and a metal foreign object bin. The bottom of the sorting bin is configured to be electrically openable. A five-level robotic arm is set on the same side as the five-level sorting box. The five-level robotic arm has a five-level robotic hand and a five-level industrial camera. The five-level robotic arm is configured to control the five-level robotic hand to grab metal foreign objects in the coal in the sorting box and transfer them to the metal foreign object box based on the image information of the five-level industrial camera. A five-stage ultrasonic detector is installed on the five-stage robotic arm to detect metallic foreign objects in the coal in the sorting bin; A five-stage screw conveyor has a collection box and a screw conveyor pipe. The bottom of the collection box is concave towards the center, and the bottom inlet of the screw conveyor pipe is located at the lowest point in the middle of the collection box. A return pipe is provided at the outlet of the screw conveyor pipe. The end of the return pipe away from the screw conveyor pipe slopes downward and is located above the coal conveyor belt. A guide groove is provided on one side of the collection box. The end of the guide groove away from the collection box slopes upward and is located at the bottom of the sorting bin. The fifth-level robotic arm is configured to drive the fifth-level robotic hand to move and cover the fifth-level sorting box. After the bottom of the sorting bin is opened, the guide trough guides the coal falling from the sorting bin into the collection box, and the spiral conveyor pipe transports the coal in the collection box to the coal conveyor belt.

[0014] As a preferred embodiment of the present invention, the high-speed coal plow includes a pusher plate, the bottom of the pusher plate is arc-shaped, and the curvature of the bottom of the pusher plate is the same as the curvature of the surface of the coal conveyor belt, and the bottom of the pusher plate is close to the surface edge of the coal conveyor belt. A rotating rod is provided on the surface of the push plate facing the outside of the coal conveyor belt. The other end of the rotating rod is connected to a fixed frame. The fixed frame is arranged across the frame of the coal conveyor belt, and the rotation axis of the rotating rod is collinear with the bottom bending axis of the push plate. Furthermore, a servo motor that drives the rotating rod to rotate is provided on the fixed frame. When the rotating rod pushes the push plate to rotate, the bottom of the push plate can slide against the arc-shaped surface of the coal conveyor belt to push this section of coal out from the side of the coal conveyor belt. Furthermore, the length of the pusher plate along the conveying direction is equal to the length of the primary sorting area.

[0015] As a preferred embodiment of the present invention, partition plates are provided at both ends of the push plate in the conveying direction, the partition plates extend toward the inner side of the coal conveying belt, and the ends of the partition plates away from the push plate abut against the surface edge of the coal conveying belt. The bottom of the partition plate forms an arc surface along its extension direction, and the curvature of the bottom arc surface of the partition plate is the same as the curvature of the surface of the coal conveyor belt. When the rotating rod pushes the push plate to rotate, the bottom of the partition plate can slide against the arc-shaped surface of the coal conveyor belt to separate the upstream and downstream coal and prevent the coal in the push plate area from falling upstream or downstream.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a cascaded sorting method consisting of five sorting units. First-level sorting detects and removes large metal foreign objects; second-level sorting detects and removes magnetic metal foreign objects using magnetic separation; third and fourth-level sorting use diversion and sieving to progressively reduce the volume of non-magnetic foreign objects, thus lowering the sorting burden; and fifth-level sorting detects and removes non-magnetic metal foreign objects again, effectively improving the removal rate of both magnetically attracted and non-magnetic metal foreign objects. Attached Figure Description

[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] Figure 1 This is a front view schematic diagram of the structural composition of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention; Figure 2 This is a rear view schematic diagram of the structural composition of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention; Figure 3 A schematic diagram showing the components of the primary sorting unit and the secondary sorting unit of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention; Figure 4 A schematic diagram of the three-stage sorting unit of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention; Figure 5 A schematic diagram of the secondary sorting unit of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention; Figure 6 A schematic diagram showing the partial composition of the four-stage and five-stage sorting units of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the high-speed coal plowing device of the metal foreign object removal system for a coal conveyor belt provided in an embodiment of the present invention.

[0019] The labels in the diagram represent the following: 1-Primary sorting unit; 11-Large metal foreign object recycling bin; 12-Primary robotic arm; 13-Primary ultrasonic detector; 121-Primary robotic arm; 122-Primary industrial camera; 2-Secondary sorting unit; 21-Magnetic metal recycling box; 22-High-speed coal plow; 23-Secondary screw conveyor; 24-Secondary belt conveyor; 25-Secondary ultrasonic detector; 221-Push plate; 222-Rotating rod; 223-Fixed frame; 224-Separator plate; 241-Permanent magnet drum; 3-Three-stage sorting unit; 31-Three-stage conveyor belt; 32-Irregular tee; 33-Drum screen; 34-Three-stage ultrasonic detector; 321-First material discharge channel; 322-Second material discharge channel; 323-Tee baffle; 331-Fine material outlet; 332-Coarse material outlet; 4-Fourth-level sorting unit; 41-Fourth-level conveyor belt; 42-Pushing rake mechanism; 43-Coal chute; 44-Fourth-level ultrasonic detector; 421-First push rake; 422-Second push rake; 5 - Level 5 sorting unit; 51 - Level 5 sorting box; 52 - Level 5 robotic arm; 53 - Level 5 ultrasonic detector; 54 - Level 5 screw conveyor; 521 - Level 5 robotic arm; 522 - Level 5 industrial camera; 541 - Collection box; 542 - Screw conveyor pipe; 543 - Return pipe; 544 - Guide trough. Detailed Implementation

[0020] The technical solutions of 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figure 1 , Figure 2 As shown, the present invention provides a method for removing metallic foreign objects from a coal conveyor belt, comprising the following steps: Primary sorting: Upstream of the coal conveyor belt, large metal foreign objects are detected by ultrasonic detection, and a primary robotic arm and camera are used to locate and grab them, removing large magnetic and non-magnetic metal foreign objects from the coal. Secondary sorting: Downstream of the coal conveyor belt, metal detection is performed on the coal after primary sorting. When a metal foreign object is detected, this section of coal is pushed off the coal conveyor belt onto the secondary belt. The permanent magnet roller of the secondary belt adsorbs the magnetic metal foreign object and removes it from the bottom, while the coal is discharged from the discharge end. Through a combination of magnetic separation and diversion, the magnetic metal foreign object is separated from the coal and non-magnetic metal foreign objects. Three-stage sorting: The three-stage conveyor belt receives the coal discharged from the discharge end of the two-stage conveyor belt. Metal detection is performed on the coal after the two-stage sorting. When a metal foreign object is detected, the coal containing non-magnetic metal foreign objects is conveyed to the drum screen for screening through the diversion mechanism. Coal smaller than 10mm is screened and discharged onto the coal conveyor belt, while coal larger than 10mm is discharged outside the coal conveyor belt. When no metal foreign object is detected, the coal is directly discharged onto the coal conveyor belt through the diversion mechanism. Fourth-level sorting: The fourth-level belt receives coal material larger than 10mm that was rejected in the third-level sorting and performs metal detection on the coal material conveyed on the fourth-level belt. When a non-magnetic metal foreign object is detected, a pusher is used to push this section of coal material off the fourth-level belt to remove it; when no non-magnetic metal foreign object is detected, the coal material is directly dropped onto the conveyor belt. Five-stage sorting: The sorting box is used to collect the coal and non-metallic foreign objects that have been rejected by the four-stage sorting and to detect metal. Then, the first-stage robotic arm and camera are used to locate and grab the remaining non-magnetic metal foreign objects. The coal with the non-magnetic metal foreign objects removed is dropped into the collection box and then transported to the coal conveyor belt by the screw conveyor. The coal conveyor belt intermittently transports coal according to the set conveying distance, and the coal conveyor belt restarts after the first and second sorting processes are completed.

[0022] The primary sorting stage involves metal detection, sorting, and grabbing to separate large metallic foreign objects (including magnetic and non-magnetic metals). The secondary sorting stage separates magnetic metallic foreign objects. The tertiary and quaternary sorting stages progressively reduce the amount of metallic foreign objects, and the quinary stage involves metal detection, sorting, and grabbing to remove non-magnetic metallic foreign objects. Finally, the remaining coal after removing metallic foreign objects is returned to the conveyor belt. Through multi-stage reduction sorting, the content of metallic foreign objects in the transported coal is effectively reduced.

[0023] This means that magnetic and non-magnetic metallic foreign objects in coal are removed through detection, reduction and diversion of metallic foreign objects, magnetic separation, screening, and mechanical grasping for precise sorting.

[0024] In the four-stage sorting process, there are at least two pushers, each pusher corresponding to an ultrasonic detector. The pushers and ultrasonic detectors are arranged sequentially along the conveying direction of the four-stage belt. Each ultrasonic detector is set on the material receiving side of the corresponding pusher to form redundant detection of metallic foreign objects in the coal.

[0025] By setting up two pusher rakes in the fourth-level sorting, and using an ultrasonic detector to detect metallic foreign objects in the coal before each pusher rake, the possibility of missing detection can be prevented.

[0026] The following are methods for removing metallic foreign objects from coal conveyor belts, such as... Figure 1 , Figure 2 As shown, an exclusion system is provided, comprising: The coal conveyor belt is equipped with a first-level sorting unit 1, a second-level sorting unit 2, a third-level sorting unit 3, a fourth-level sorting unit 4, and a fifth-level sorting unit 5 in sequence along the conveying direction of the coal conveyor belt; Level 1 sorting unit 1 is used for level 1 sorting, Level 2 sorting unit 2 is used for level 2 sorting, Level 3 sorting unit 3 is used for level 3 sorting, Level 4 sorting unit is used for level 4 sorting, and Level 5 sorting unit 5 is used for level 5 sorting.

[0027] The coal conveyor belt serves as the main route for coal transportation throughout the entire process. Along its conveying direction, it sequentially integrates primary sorting unit 1, secondary sorting unit 2, tertiary sorting unit 3, quaternary sorting unit 4, and quinary sorting unit 5. The system control center (not shown in the diagram) coordinates the working status and actions of the coal conveyor belt and each sorting unit.

[0028] Furthermore, based on the above method, the coal conveyor belt does not operate continuously, but rather intermittently and stepwise, conveying coal over a preset, fixed distance (defined as the "standard coal section length"). That is, after each conveying action is completed, the coal conveyor belt pauses, and the system, based on the detection results of the primary sorting unit 1 and the secondary sorting unit 2, completes the corresponding sorting actions while the coal conveyor belt is stationary. Once all necessary sorting actions are confirmed, the belt restarts to convey the next standard coal section. This ensures that every section of coal on the conveyor belt can be accurately detected and processed while stationary or relatively stationary, avoiding dynamic misjudgments and execution deviations.

[0029] like Figure 3 As shown, the primary sorting unit 1 includes: Large metal foreign object recovery box 11 is installed on one side of the coal conveyor belt; A primary robotic arm 12 is located upstream of the conveyor belt and on the same side as the large metal foreign object recovery box 11. It has a primary robotic arm 121 and a primary industrial camera 122. The primary robotic arm 12 is configured to control the primary robotic arm 121 to grab large metal foreign objects in the coal according to the image information of the primary industrial camera 122. A primary ultrasonic detector 13 is installed on the coal conveyor belt, with the detection end of the primary ultrasonic detector 13 facing the feed end surface of the coal conveyor belt, and is used to detect metallic foreign objects in the coal. In this process, the coal conveyor belt intermittently transports coal through the first-stage ultrasonic detector 13 to form a coal section. When the first-stage robotic arm 12 detects a metallic foreign object in the first-stage ultrasonic detector 13, it grabs the object in the coal section using the first-stage robotic arm 121 and the first-stage industrial camera 122, and removes large magnetic and non-magnetic metallic foreign objects from the coal into the large metallic foreign object recovery box 11.

[0030] In this embodiment, the primary sorting unit 1 is located at the upstream end of the system. The primary ultrasonic detector 13 is installed above the coal conveyor belt, aligned with the conveyor belt in the direction of material feeding, and is used to perform an initial full-area scan of the incoming coal, mainly to identify larger metallic foreign objects.

[0031] A primary robotic arm 12 is deployed on one side of the conveyor belt, and its end effector, a primary robotic hand 121, integrates a primary industrial camera 122 for precise positioning to accurately grasp large metal foreign objects in the coal.

[0032] The large metal foreign object recycling bin 11 is placed within the working range of the robotic arm. The first-level robotic arm 12 can control the first-level robotic hand 121 to sort large metal foreign objects into the large metal foreign object recycling bin 11.

[0033] Specifically, when the primary ultrasonic detector 13 detects a metallic foreign object signal within a standard coal section conveyed by the coal conveyor belt, the conveyor belt stops transporting coal. Based on the approximate location of the ultrasonic signal, the system control center directs the primary robotic arm 12 to move above the coal section. The primary industrial camera 122 acquires and identifies images of the coal section surface, precisely locating the coordinates of the metallic foreign object. Subsequently, the primary robotic arm 121 performs a grasping operation, removing the identified large metallic foreign object (whether magnetic or non-magnetic) and placing it into the recycling bin 11. After this process is completed, the system allows the coal conveyor belt to proceed with the next transport. If no large metallic foreign object signal is detected, the belt will directly transport the next section of coal after a brief pause.

[0034] like Figure 3 , Figure 4 , Figure 5 As shown, the secondary sorting unit 2 includes: Magnetic metal recycling box 21 is located below one side of the coal conveyor belt; The high-speed coal plow 22 is located in the middle of the coal conveyor belt. The high-speed coal plow is configured to move horizontally on the coal conveyor belt in a direction perpendicular to the conveying direction in order to push a section of coal off the side of the coal conveyor belt. The secondary screw conveyor 23 is set on one side of the coal conveying belt and opposite to the high-speed coal plow 22. The feed inlet of the secondary screw conveyor 23 is lower than the side of the coal conveying belt to catch the coal pushed down by the high-speed coal plow 22. The secondary belt 24 is located below the secondary screw conveyor. One end of the belt is used to collect the coal discharged from the outlet of the secondary screw conveyor 23. The secondary belt 24 has a permanent magnet drum 241 away from the outlet of the secondary screw conveyor 23. The permanent magnet drum 241 is configured to attract magnetic metal foreign objects to the surface of the secondary belt 24, so that they rotate to the bottom of the permanent magnet drum 241 and fall into the magnetic metal recycling box 21 after moving away from the permanent magnet drum 241. The secondary ultrasonic detector 25 is installed on the coal conveyor belt and located downstream of the primary ultrasonic detector 13. The detection end of the secondary ultrasonic detector 25 faces the surface of the coal conveyor belt and is used to detect metallic foreign objects in the coal. The secondary ultrasonic detector 25 and the primary ultrasonic detector 13 form a primary sorting area. Among them, the first-level robotic arm 12 controls the first-level robotic hand 121 to cover the first-level sorting area, and the distance between the high-speed coal plow 22 and the second-level ultrasonic detector 25 is an integer multiple of the length of the first-level sorting area. Furthermore, the conveying distance of each intermittent conveyor belt is equal to the length of the primary sorting zone; Furthermore, when the high-speed coal plow 22 moves to the working area of ​​the coal section where the secondary ultrasonic detector 25 detects a metallic foreign object, the high-speed coal plow 22 pushes the coal off the coal conveyor belt. Furthermore, if the secondary ultrasonic detector 25 does not detect any metallic foreign objects, or if the secondary ultrasonic detector 25 detects metallic foreign objects and the coal material in this section is transported to the working area of ​​the high-speed coal plow 22, the high-speed coal plow 22 will not work, so that the coal conveyor belt can transport the coal material downstream.

[0035] The secondary sorting unit 2 is located downstream of the primary sorting unit 1. It includes a secondary ultrasonic detector 25, a high-speed coal plow 22, a secondary screw conveyor 23, a secondary belt conveyor 24, and a permanent magnet drum 241. The area between the secondary ultrasonic detector 25 and the primary ultrasonic detector 13 is defined as the "primary sorting zone." The high-speed coal plow 22 is installed at a specific downstream position from the secondary ultrasonic detector 25. This distance from the secondary ultrasonic detector 25 is designed to be an integer multiple of the "primary sorting zone length," such as one or two times, to ensure that the detected coal segment can be accurately pushed towards the high-speed coal plow 22.

[0036] Specifically, after primary sorting, the coal is passed through the secondary ultrasonic detector 25 in standard coal sections. If a coal section is detected to contain metallic foreign objects (mainly small or medium-sized pieces not picked up by the primary sorting), the system will record this signal. When the coal section is conveyed to the high-speed plow 22, the conveyor belt pauses (within the set single conveying distance). The high-speed plow 22 then operates, precisely pushing the entire coal section into the feed inlet of the side screw conveyor 23.

[0037] The screw conveyor 23 transfers the coal to the secondary belt conveyor 24. As the coal passes the permanent magnet drum 241 at its end, magnetic metal foreign objects are strongly attracted to the belt surface. As the belt rotates to the non-magnetic area at the bottom of the drum, they fall into the magnetic metal recovery box 21 due to gravity. The coal and any remaining non-magnetic materials are discarded from the discharge end of the secondary belt conveyor 24 and enter the next sorting unit. If no metal is detected in a coal section, the high-speed plow 22 does not activate, and the coal passes directly, continuing to be conveyed on the coal conveyor belt.

[0038] Furthermore, because the high-speed plow 22 pushes the coal section into the screw conveyor 23, it achieves secondary dispersion of the coal section onto the secondary belt 24, thus making its spreading more uniform and effectively improving the magnetic separation effect. In addition, the use of permanent magnet roller 241 to adsorb magnetic metal foreign objects can adsorb magnetic metal foreign objects onto the coal conveyor belt at close range. The magnetic attraction effect is better than that of electromagnetic devices suspended above the coal conveyor belt, and automatic adsorption and automatic detachment can be achieved without power supply.

[0039] During this process, in order to ensure that the high-speed coal plow 22 can push the coal off the coal conveyor belt and reduce the amount of coal spilled, such as... Figure 7 As shown, the high-speed coal plow 22 includes a push plate 221. The bottom of the push plate 221 is arc-shaped, and the curvature of the bottom of the push plate 221 is the same as the curvature of the surface of the coal conveyor belt. The bottom of the push plate 221 is close to the surface edge of the coal conveyor belt. A rotating rod 222 is provided on the surface of the push plate 221 facing the outer side of the coal conveyor belt. The other end of the rotating rod 222 is connected to a fixed frame 223. The fixed frame 223 is installed across the frame of the coal conveyor belt, and the rotation axis of the rotating rod 222 is collinear with the bottom bending axis of the push plate 221. Furthermore, a servo motor that drives the rotating rod 222 to rotate is installed on the fixed frame 223. When the rotating rod 222 pushes the push plate 221 to rotate, the bottom of the push plate 221 can slide against the arc surface of the coal conveyor belt to push this section of coal out from the side of the coal conveyor belt. Furthermore, the length of the push plate 221 along the conveying direction is equal to the length of the primary sorting area.

[0040] In this embodiment, when the push plate 221 is in operation, its bottom edge can form a surface contact or a line contact with a very small gap with the belt surface, rather than a point contact.

[0041] Specifically, when the servo motor drives the rotating rod 222 to rotate, causing the push plate 221 to swing to the side of the coal conveyor belt, the arc-shaped bottom of the push plate 221 can slide close to the surface of the coal conveyor belt like a "scraper", ensuring that the coal material accumulated on the coal conveyor belt can be scraped up and guided out almost completely, greatly reducing the coal material residue caused by the gap between the bottom of the push plate 221 and the belt.

[0042] Furthermore, the rotation axis of the rotating rod 222 and the bending axis of the bottom of the push plate 221 are set to be collinear. Thus, the rotational motion of the push plate 221 is carried out around the contact line between itself and the coal conveyor belt. This makes the contact position between the push plate 221 and the coal conveyor belt change continuously and smoothly during the operation, effectively reducing the probability of severe friction caused by mismatch of the rotation center.

[0043] Furthermore, the primary sorting area is the basic unit for the system to segment coal materials. Matching the length of the pusher plate 221 to this ensures that each movement of the high-speed coal plow 22 is precisely aimed at a complete "problem coal segment" that has been confirmed by the secondary ultrasonic detector 25. This achieves precise alignment between the action and the coal segment, avoiding incomplete pushing or mistakenly pushing adjacent "metal-free" coal segments.

[0044] Furthermore, such as Figure 7As shown, partition plates 224 are provided at both ends of the push plate 221 in the conveying direction. The partition plates 224 extend toward the inside of the coal conveyor belt, and their ends away from the push plate 221 abut against the surface edge of the coal conveyor belt. The bottom of the separator 224 forms an arc surface along its extension direction, and the curvature of the bottom arc surface of the separator 224 is the same as the curvature of the surface of the coal conveyor belt. When the rotating rod 222 pushes the push plate 221 to rotate, the bottom of the partition plate 224 can slide against the arc-shaped surface of the coal conveyor belt to separate the upstream and downstream coal and prevent the coal in the area of ​​the push plate 221 from falling upstream or downstream.

[0045] At both ends of the push plate 221, a partition plate 224 extending inward toward the belt is added. Its bottom is also machined into an arc surface consistent with the curvature of the belt, and its end lightly touches the edge of the belt in the initial position.

[0046] The partition plate 224 forms two physical barriers in the upstream and downstream directions of the pushing area, preventing the coal in the target coal section from overflowing in the forward and backward directions (i.e., the conveying direction) when subjected to lateral thrust.

[0047] Furthermore, the arc-shaped bottom of the partition plate 224 slides on the belt surface, forming a dynamic seal, further blocking the possibility of coal escaping from the gap between the push plate and the belt. In addition, the partition plate 224 confines the coal within the "U-shaped" space formed by the main body of the push plate 221 and the two partition plates 224, forcing all the coal to move towards the side screw conveyor 23 under the push of the push plate, thus realizing the directional and aggregated transfer of the coal.

[0048] Specifically, when the secondary ultrasonic detector 25 detects a metallic foreign object in a standard coal section, and this section is being conveyed below the high-speed coal plow 22, the system controls the conveyor belt to pause. Subsequently, the servo motor starts, driving the rotary rod 222 to rotate the entire pusher plate 221 and separator plate 224 in a direction perpendicular to the conveying belt. The arc-shaped bottom of the pusher plate 221 adheres to the belt surface, scraping the coal off the conveyor belt. Simultaneously, the separator plates 224 on both sides slide synchronously, isolating the working area and preventing longitudinal diffusion of the coal. Under the continuous pushing of the pusher plate 221, the target coal section is pushed laterally into the waiting screw conveyor 23 in a relatively complete and clean manner, completing its separation from the main belt.

[0049] like Figure 4 , Figure 6 As shown, the three-level sorting unit 3 includes: The third-stage conveyor belt 31 has its feed end located below the discharge end of the second-stage conveyor belt 24 to catch the coal falling from the second-stage conveyor belt 24, and its discharge end is located above the coal conveyor belt. The irregular tee 32 has its inlet located below the outlet end of the three-stage conveyor belt 31, and has a first discharge channel 321 and a second discharge channel 322 inside, as well as a tee baffle 323 located at the inlet. The tee baffle 323 is configured to be driven by a motor located outside the irregular tee 32 to adjust the blocking direction, so as to select to block the first discharge channel 321 or the second discharge channel 322. The outlet of the first discharge channel 321 is located above the coal conveyor belt and is used to discharge coal directly onto the coal conveyor belt. The drum screen 33 is used to screen the coal inside it. Its inlet is connected to the outlet of the second discharge channel 322 to receive the coal discharged from the second discharge channel 322. The drum screen 33 has a fine material outlet 331 and a coarse material outlet 332. The fine material outlet 331 is located above the coal conveyor belt and is used to discharge the coal directly onto the coal conveyor belt. The coarse material outlet 332 is connected to the fourth-level sorting unit 4. A three-stage ultrasonic detector 34 is installed on a three-stage conveyor belt 31, with the detection end of the three-stage ultrasonic detector 34 facing the surface of the three-stage conveyor belt 31, and is used to detect metallic foreign objects in the coal. Among them, when the third-level ultrasonic detector 34 is close to the material drop end of the third-level belt 31, when the third-level ultrasonic detector 34 detects a metal foreign object, the three-way baffle 323 blocks the first material drop channel 321 so that this section of coal material is discharged from the second material drop channel 322 into the drum screen 33 for screening. Furthermore, when the three-stage ultrasonic detector 34 does not detect any metallic foreign objects, the three-way baffle 323 blocks the second material discharge channel 322 so that this section of coal can be directly discharged from the first material discharge channel 321 onto the coal conveyor belt.

[0050] The third-level sorting unit 3 is responsible for processing the coal after the second-level sorting. The third-level conveyor belt 31 receives the material falling from the second-level conveyor belt 24. The third-level ultrasonic detector 34 is installed above the third-level conveyor belt 31 near the discharge end. The irregularly shaped tee 32 is located below the discharge end of the third-level conveyor belt 31, and it is equipped with an electrically controllable tee baffle 323 for switching between the first discharge channel 321 (straight-through) and the second discharge channel 322 (leading to the drum screen 33). The fine material outlet 331 (<10mm) of the drum screen 33 is aligned with the main coal conveyor belt, while the coarse material outlet 332 (>10mm) is aligned with the fourth-level sorting unit.

[0051] Specifically, the material from the secondary conveyor belt 24 falls onto the tertiary conveyor belt 31, is transported, and passes through the tertiary ultrasonic detector 34. If a metallic foreign object is detected (after secondary magnetic separation, the target is mainly non-magnetic metal), when this part of the material reaches the irregular tee 32, the tee baffle 323 switches, blocking the first channel 321 and opening the second channel 322, allowing the material to enter the drum screen 33. Inside the drum screen 33, the material is screened: fine coal particles (determined to be clean) are directly returned to the main conveyor belt through the fine material outlet 331; coarse particles (which may contain or be metallic foreign objects) are discharged through the coarse material outlet 332. If the tertiary detector 34 does not detect metal, the tee baffle 323 allows the coal to pass through the first channel 321 and fall directly back onto the main conveyor belt. The action of the tee baffle 323 can be delayed based on the conveying speed of the tertiary conveyor belt 31 to prevent excessive coal from accidentally entering the first discharge channel 321 or the second discharge channel 322.

[0052] like Figure 6 As shown, the four-level sorting unit 4 includes: The fourth-stage belt 41 has its feed end located below the coarse material outlet 332 to receive the coal discharged from the coarse material outlet 332, and the fourth-stage belt 41 is located above the coal conveying belt. The pusher mechanism 42 is located on one side of the fourth-stage belt 41 and has a first pusher 421 and a second pusher 422. The first pusher 421 and the second pusher 422 are arranged sequentially along the conveying direction of the fourth-stage belt 41. The first pusher 421 and the second pusher 422 are configured to push the coal on the fourth-stage belt 41 off in a direction perpendicular to the fourth-stage belt 41. The first pusher 421 and the second pusher 422 work independently. The coal chute 43 is located on the other side of the fourth-stage conveyor belt 41 and opposite to the pusher mechanism 42. It is used to guide the coal pushed down by the first pusher 421 and the second pusher 422 to be discharged in a directional manner. The lower end of the coal chute 43 is connected to the fifth-stage sorting unit 5. A fourth-level ultrasonic detector 44 is provided on the upstream side of the first push rake 421 and the second push rake 422. The first push rake 421 and the second push rake 422 are configured to operate according to the detection signal of the fourth-level ultrasonic detector 44 on the upstream side. When the first level 4 ultrasonic detector 44 detects a metallic foreign object, the first pusher 421 pushes the section of coal to the coal chute 43. When the first level 4 ultrasonic detector 44 does not detect a metallic foreign object, but the second level 4 ultrasonic detector 44 detects a metallic foreign object, the second pusher 421 pushes the section of coal to the coal chute 43. Furthermore, when neither of the two level-four ultrasonic detectors 44 detects any metallic foreign objects, the level-four conveyor belt 41 directly discharges the coal onto the coal conveyor belt.

[0053] The fourth-stage conveyor belt 41 receives material from the coarse material outlet 332 of the drum screen 33. Along its conveying direction, a first fourth-stage ultrasonic detector 44a, a first pusher 421, a second fourth-stage ultrasonic detector 44b, and a second pusher 422 are sequentially installed. The first and second pushers 421 and 422 can be controlled independently and move perpendicular to the conveyor belt. A coal chute 43 is located on the other side of the conveyor belt to guide the coal pushed out by the first and second pushers 421 and 422.

[0054] Specifically, coarse material is conveyed on the fourth-stage conveyor belt 41. When it passes the first fourth-stage ultrasonic detector 44a, if it is detected to contain metallic foreign objects, the first pusher 421 will activate when it reaches the position of the first pusher 421, pushing the material section onto the chute 43 and into the fifth-stage sorting unit. If the first fourth-stage ultrasonic detector 44a fails to detect (missed detection), but the material is detected when it continues to be conveyed to the second fourth-stage ultrasonic detector 44b, the system will instruct the second pusher 422 to activate when the material section reaches its position, performing a push-off operation to achieve redundant removal. Only material that does not trigger an alarm at either of the two detection points is allowed to be directly discharged back to the main coal conveyor belt from the discharge end of the fourth-stage conveyor belt 41.

[0055] like Figure 6 As shown, the five-level sorting unit 5 includes: The fifth-level sorting box 51 is located on one side of the coal conveyor belt. The fifth-level sorting box 51 has a sorting bin and a metal foreign object bin. The bottom of the sorting bin is configured to be electrically opened. A five-level robotic arm 52 is set on the same side as the five-level sorting box 51. The five-level robotic arm 52 has a five-level robotic hand 521 and a five-level industrial camera 522. The five-level robotic arm 52 is set to control the five-level robotic hand 521 to grab metal foreign objects in the coal in the sorting box and transfer them to the metal foreign object bin according to the image information of the five-level industrial camera 522. A five-stage ultrasonic detector 53 is mounted on a five-stage robotic arm 52 and is used to detect metallic foreign objects in the coal in the sorting bin. The five-stage screw conveyor 54 has a collection box 541 and a screw conveyor pipe 542. The bottom of the collection box 541 is concave towards the middle. The bottom inlet of the screw conveyor pipe 542 is located at the lowest point in the middle of the collection box 541. A return pipe 543 is provided at the outlet of the screw conveyor pipe 542. The end of the return pipe 543 away from the screw conveyor pipe 542 is inclined downward and located above the coal conveyor belt. A guide groove 544 is provided on one side of the collection box 541. The end of the guide groove 544 away from the collection box 541 is inclined upward and located at the bottom of the sorting bin. Among them, the fifth-level robotic arm 52 is configured to drive the fifth-level robotic hand 521 to cover the movement of the fifth-level sorting box 51; After the bottom of the sorting bin is opened, the guide chute 534 guides the coal falling from the sorting bin into the collection box 531, and the spiral conveyor pipe 532 transports the coal in the collection box 531 to the coal conveying belt.

[0056] The five-stage sorting box 51 is used to receive materials from the coal chute 43. The five-stage ultrasonic detector 53 and the five-stage industrial camera 522 are mounted on the five-stage robotic arm 52 and can scan the coal pile inside the sorting box 51 as the robotic arm moves.

[0057] Specifically, after the coal is fed into the five-stage sorting box 51, the five-stage ultrasonic detector 53 performs a comprehensive scan to confirm the presence of metal. Subsequently, the five-stage robotic arm 52 drives the five-stage industrial camera 522 to perform a multi-angle visual scan of the coal pile, accurately locating the position of residual non-magnetic metal foreign objects. Finally, the five-stage robotic arm 521 performs a gripping action, moving the foreign object into the adjacent metal foreign object bin (for manual handling or removal by the robotic arm), completing the final fine sorting.

[0058] After sorting is completed, the bottom of the sorting bin is opened electrically (using a conventional electric gate or door structure), and the remaining coal falls onto the guide trough 534 and enters the collection box 531 along the guide trough 534. It then converges towards the low point at the feed inlet of the spiral conveyor pipe 532, is conveyed upward by the spiral conveyor pipe 532, and is directionally returned to the coal conveying belt through the return pipe 543.

[0059] It is worth noting that the entire system uses the intermittent stepping of the coal conveyor belt as its rhythm and multi-stage ultrasonic detection as its sensing method, forming a serial sorting production line. The coal material sequentially undergoes: large-item grabbing; magnetic adsorption separation; non-magnetic detection and particle size screening; redundant detection to remove coarse material; and finally, visual fine sorting. Each stage targets specific types or states of metallic foreign objects, and the stages are closely connected by conveyor belts, chutes, and other transfer mechanisms. The system control center can precisely schedule the robotic arms, high-speed plows, three-way baffles, and pushers to operate on the correct coal sections at the correct time based on the detection results from each stage, achieving full automation, high reliability, and a high rejection rate.

[0060] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A method for removing metallic foreign objects from a coal conveyor belt, characterized in that, Includes the following steps: Primary sorting: Upstream of the coal conveyor belt, large metal foreign objects are detected by ultrasonic detection, and a primary robotic arm and camera are used to locate and grab them, removing large magnetic and non-magnetic metal foreign objects from the coal. Secondary sorting: Downstream of the coal conveyor belt, metal detection is performed on the coal after primary sorting. When a metal foreign object is detected, this section of coal is pushed off the coal conveyor belt onto the secondary belt. The permanent magnet roller of the secondary belt adsorbs the magnetic metal foreign object and removes it from the bottom, while the coal is discharged from the discharge end. Through a combination of magnetic separation and diversion, the magnetic metal foreign object is separated from the coal and non-magnetic metal foreign objects. Three-stage sorting: The three-stage conveyor belt receives the coal discharged from the discharge end of the two-stage conveyor belt. Metal detection is performed on the coal after the two-stage sorting. When a metal foreign object is detected, the coal containing non-magnetic metal foreign objects is conveyed to the drum screen for screening through the diversion mechanism. Coal smaller than 10mm is screened and discharged onto the coal conveyor belt, while coal larger than 10mm is discharged outside the coal conveyor belt. When no metal foreign object is detected, the coal is directly discharged onto the coal conveyor belt through the diversion mechanism. Fourth-level sorting: The fourth-level belt receives coal material larger than 10mm that was rejected in the third-level sorting and performs metal detection on the coal material conveyed on the fourth-level belt. When a non-magnetic metal foreign object is detected, a pusher is used to push this section of coal material off the fourth-level belt to remove it; when no non-magnetic metal foreign object is detected, the coal material is directly dropped onto the conveyor belt. Five-stage sorting: The sorting box is used to collect the coal and non-metallic foreign objects that have been rejected by the four-stage sorting and to detect metal. Then, the first-stage robotic arm and camera are used to locate and grab the remaining non-magnetic metal foreign objects. The coal with the non-magnetic metal foreign objects removed is dropped into the collection box and then transported to the coal conveyor belt by the screw conveyor. The coal conveyor belt intermittently transports coal according to a set conveying distance, and the coal conveyor belt restarts after the first and second sorting processes are completed.

2. The method for removing metallic foreign objects from a coal conveyor belt according to claim 1, characterized in that, In the four-stage sorting process, there are at least two pushers, each pusher corresponding to an ultrasonic detector. The pushers and ultrasonic detectors are arranged sequentially along the conveying direction of the four-stage belt. Each ultrasonic detector is located on the material receiving side of the corresponding pusher to form redundant detection of metallic foreign objects in the coal.

3. A foreign object removal system employing the method for removing metallic foreign objects from a coal conveyor belt as described in claim 2, characterized in that, include: The coal conveyor belt is provided with a first-level sorting unit (1), a second-level sorting unit (2), a third-level sorting unit (3), a fourth-level sorting unit (4) and a fifth-level sorting unit (5) in sequence along the conveying direction of the coal conveyor belt. The first-level sorting unit (1) is used for first-level sorting, the second-level sorting unit (2) is used for second-level sorting, the third-level sorting unit (3) is used for third-level sorting, the fourth-level sorting unit is used for fourth-level sorting, and the fifth-level sorting unit (5) is used for fifth-level sorting.

4. A metal foreign object removal system for a coal conveyor belt according to claim 3, characterized in that, The primary sorting unit (1) includes: A large metal foreign object recovery box (11) is installed on one side of the coal conveyor belt; A primary robotic arm (12) is located upstream of the conveyor belt and on the same side as the large metal foreign object recovery box (11). It has a primary robotic arm (121) and a primary industrial camera (122) is installed on the primary robotic arm (121). The primary robotic arm (12) is configured to control the primary robotic arm (121) to grab large metal foreign objects in the coal according to the image information of the primary industrial camera (122). A primary ultrasonic detector (13) is installed on the coal conveyor belt, with the detection end of the primary ultrasonic detector (13) facing the feed end surface of the coal conveyor belt, for detecting metallic foreign objects in the coal. In this process, the coal conveyor belt intermittently transports coal through the first-level ultrasonic detector (13) to form a coal section. When the first-level robotic arm (12) detects a metal foreign object in the first-level ultrasonic detector (13), it grabs the object in the coal section using the first-level robotic arm (121) and the first-level industrial camera (122) and removes large magnetic and non-magnetic metal foreign objects from the coal into the large metal foreign object recovery box (11).

5. A metal foreign object removal system for a coal conveyor belt according to claim 4, characterized in that, The secondary sorting unit (2) includes: A magnetic metal recycling box (21) is located below one side of the coal conveyor belt; A high-speed coal plow (22) is provided in the middle of the coal conveyor belt. The high-speed coal plow is configured to move horizontally on the coal conveyor belt in a direction perpendicular to the conveying direction in order to push a section of coal off the side of the coal conveyor belt. A secondary screw conveyor (23) is set on one side of the coal conveying belt and opposite to the high-speed coal plow (22). The feed inlet of the secondary screw conveyor (23) is lower than the side of the coal conveying belt to catch the coal pushed down by the high-speed coal plow (22). A secondary belt (24) is disposed below the secondary screw conveyor (23). One end of the belt is used to collect the coal discharged from the outlet of the secondary screw conveyor (23). The secondary belt (24) has a permanent magnet roller (241) away from the outlet of the secondary screw conveyor (23). The permanent magnet roller (241) is configured to attract magnetic metal foreign objects to the surface of the secondary belt (24) so ​​that they rotate to the bottom of the permanent magnet roller (241) and fall into the magnetic metal recycling box (21) away from the permanent magnet roller (241). A secondary ultrasonic detector (25) is installed on the coal conveyor belt and located downstream of the primary ultrasonic detector (13). The detection end of the secondary ultrasonic detector (25) faces the surface of the coal conveyor belt and is used to detect metallic foreign objects in the coal. A primary sorting area is formed between the secondary ultrasonic detector (25) and the primary ultrasonic detector (13). Wherein, the first-level robotic arm (12) controls the movement range of the first-level robotic hand (121) to cover the first-level sorting area, and the distance between the high-speed coal plow (22) and the second-level ultrasonic detector (25) is an integer multiple of the length of the first-level sorting area; Furthermore, the conveying distance of each intermittent conveying operation of the coal conveyor belt is equal to the length of the primary sorting area; Furthermore, when the high-speed coal plow (22) moves to the action area of ​​the high-speed coal plow (22) after the secondary ultrasonic detector (25) detects a coal section containing a metallic foreign object, the high-speed coal plow (22) pushes the coal on the coal conveyor belt off. Furthermore, if the secondary ultrasonic detector (25) does not detect any metallic foreign objects, or if the secondary ultrasonic detector (25) detects any metallic foreign objects and the coal material in this section is transported to the working area of ​​the high-speed coal plow (22), the high-speed coal plow (22) will not work, so that the coal conveying belt can transport coal downstream.

6. A metal foreign object removal system for a coal conveyor belt according to claim 5, characterized in that, The three-level sorting unit (3) includes: The third-stage belt (31) has its feed end located below the discharge end of the second-stage belt (24) to catch the coal falling from the second-stage belt (24), and the discharge end of the third-stage belt (31) is located above the coal conveying belt. The irregular tee (32) has its inlet located below the outlet of the three-stage belt (31), and has a first discharge channel (321) and a second discharge channel (322) inside, as well as a tee baffle (323) located at the inlet. The tee baffle (323) is configured to be driven by a motor located outside the irregular tee (32) to adjust the blocking direction, so as to select to block the first discharge channel (321) or the second discharge channel (322). The outlet of the first discharge channel (321) is located above the coal conveying belt and is used to discharge coal directly onto the coal conveying belt. A drum screen (33) is used to screen the coal inside it. Its inlet is connected to the outlet of the second discharge channel (322) to receive the coal discharged from the second discharge channel (322). The drum screen (33) has a fine material outlet (331) and a coarse material outlet (332). The fine material outlet (331) is located above the coal conveyor belt and is used to discharge the coal directly onto the coal conveyor belt. The coarse material outlet (332) is connected to the fourth-level sorting unit (4). A three-stage ultrasonic detector (34) is installed on the three-stage conveyor belt (31), with the detection end of the three-stage ultrasonic detector (34) facing the surface of the three-stage conveyor belt (31), and is used to detect metallic foreign objects in the coal. Wherein, when the third-level ultrasonic detector (34) is close to the material drop end of the third-level belt (31), when the third-level ultrasonic detector (34) detects a metal foreign object, the three-way baffle (323) blocks the first material drop channel (321) so that this section of coal is discharged from the second material drop channel (322) into the drum screen (33) for screening. When the three-stage ultrasonic detector (34) does not detect any metallic foreign objects, the three-way baffle (323) blocks the second material discharge channel (322) so that this section of coal is discharged directly from the first material discharge channel (321) onto the coal conveyor belt.

7. A metal foreign object removal system for a coal conveyor belt according to claim 6, characterized in that, The four-level sorting unit (4) includes: The fourth-stage belt (41) has its feed end located below the coarse material outlet (332) to receive the coal discharged from the coarse material outlet (332), and the fourth-stage belt (41) is located above the coal conveying belt. A pusher mechanism (42) is provided on one side of the fourth-level belt (41), and has a first pusher (421) and a second pusher (422). The first pusher (421) and the second pusher (422) are arranged sequentially along the conveying direction of the fourth-level belt (41), and the first pusher (421) and the second pusher (422) are configured to push the coal on the fourth-level belt (41) off in a direction perpendicular to the fourth-level belt (41), and the first pusher (421) and the second pusher (422) work independently. A coal chute (43) is set on the other side of the fourth-level belt (41) and opposite to the pusher mechanism (42), for guiding the coal pushed down by the first pusher (421) and the second pusher (422) to be discharged in a directional manner, and the lower end of the coal chute (43) is connected to the fifth-level sorting unit (5). A fourth-level ultrasonic detector (44) is provided on the upstream side of the first pusher (421) and the second pusher (422). The first pusher (421) and the second pusher (422) are configured to operate according to the detection signal of the fourth-level ultrasonic detector (44) on the upstream side. When the first level four ultrasonic detector (44) detects a metallic foreign object, the first pusher (421) pushes the section of coal to the coal chute (43). When the first level four ultrasonic detector (44) does not detect a metallic foreign object, and the second level four ultrasonic detector (44) detects a metallic foreign object, the second pusher (421) pushes the section of coal to the coal chute (43). Furthermore, when both of the aforementioned fourth-level ultrasonic detectors (44) detect metallic foreign objects, the fourth-level conveyor belt (41) directly discharges the coal onto the coal conveyor belt.

8. A metal foreign object removal system for a coal conveyor belt according to claim 7, characterized in that, The five-level sorting unit (5) includes: A five-stage sorting box (51) is provided on one side of the coal conveyor belt. The five-stage sorting box (51) has a sorting bin and a metal foreign object bin. The bottom of the sorting bin is configured to be electrically openable. A five-level robotic arm (52) is set on the same side as the five-level sorting box (51). The five-level robotic arm (52) has a five-level robotic hand (521) and a five-level industrial camera (522). The five-level robotic arm (52) is configured to control the five-level robotic hand (521) to grab metal foreign objects in the coal in the sorting box and transfer them to the metal foreign object box based on the image information of the five-level industrial camera (522). A five-stage ultrasonic detector (53) is installed on the five-stage robotic arm (52) and is used to detect metallic foreign objects in the coal in the sorting bin; A five-stage screw conveyor (54) has a collection box (541) and a screw conveyor pipe (542). The bottom of the collection box (541) is recessed towards the center. The bottom inlet of the screw conveyor pipe (542) is located at the lowest point in the middle of the collection box (541). A return pipe (543) is provided at the outlet of the screw conveyor pipe (542). The return pipe (543) is inclined downward at the end away from the screw conveyor pipe (542) and is located above the coal conveying belt. A guide groove (544) is provided on one side of the collection box (541). The end of the guide groove (544) away from the collection box (541) is inclined upward and placed at the bottom of the sorting bin. The fifth-level robotic arm (52) is configured to drive the fifth-level robotic hand (521) to move over the fifth-level sorting box (51); After the bottom of the sorting bin is opened, the guide groove (534) guides the coal falling from the sorting bin into the collection box (531), and the spiral conveyor pipe (532) transports the coal in the collection box (531) to the coal conveying belt.

9. A metal foreign object removal system for a coal conveyor belt according to claim 5, characterized in that, The high-speed coal plow (22) includes a push plate (221), the bottom of the push plate (221) is arc-shaped, and the degree of curvature of the bottom of the push plate (221) is the same as the degree of curvature of the surface of the coal conveying belt, and the bottom of the push plate (221) is close to the surface edge of the coal conveying belt. A rotating rod (222) is provided on the surface of the push plate (221) facing the outside of the coal conveyor belt. The other end of the rotating rod (222) is connected to a fixed frame (223). The fixed frame (223) is arranged across the frame of the coal conveyor belt, and the rotation axis of the rotating rod (222) is collinear with the bottom bending axis of the push plate (221). Furthermore, a servo motor is provided on the fixed frame (223) to drive the rotating rod (222) to rotate. When the rotating rod (222) pushes the push plate (221) to rotate, the bottom of the push plate (221) can slide against the arc surface of the coal conveyor belt to push this section of coal out from the side of the coal conveyor belt. Furthermore, the length of the push plate (221) along the conveying direction is equal to the length of the primary sorting area.

10. A metal foreign object removal system for a coal conveyor belt according to claim 9, characterized in that, Divider plates (224) are provided at both ends of the push plate (221) in the conveying direction. The divider plates (224) extend toward the inside of the coal conveying belt, and their ends away from the push plate (221) abut against the surface edge of the coal conveying belt. The bottom of the partition plate (224) forms an arc surface along its extension direction, and the curvature of the bottom arc surface of the partition plate (224) is the same as the curvature of the surface of the coal conveyor belt. When the rotating rod (222) pushes the push plate (221) to rotate, the bottom of the partition plate (224) can slide against the arc-shaped surface of the coal conveyor belt to separate the upstream and downstream coal and prevent the coal in the area of ​​the push plate (221) from falling upstream or downstream.

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