Metal detection device and method for magnetic materials

Abstract

The present invention provides a metal detection device and method for magnetic materials, belonging to the field of metal detection technology, comprising: a uniform magnetic field generating device, a belt joint identification unit, a signal processing unit, and an alarm unit; the signal processing unit collects an oscillating current signal in real time and extracts the amplitude of the oscillating current as a background signal; an initial metal alarm threshold is set according to the fluctuation amplitude of the background signal; when magnetic material is mixed with metal, the amplitude of the oscillating current instantaneously exceeds the initial alarm threshold, triggering an alarm; the signal processing unit is connected to the belt joint identification unit, and when receiving the belt joint signal, the metal alarm threshold is adjusted to be higher than the initial alarm threshold, and after the belt joint is removed, the metal impurity alarm threshold is restored to the initial alarm threshold. The present invention can effectively suppress interference between a steel cord conveyor belt and magnetic materials, thereby achieving accurate detection of metal impurities under the working conditions of the steel cord conveyor belt transporting various magnetic materials.

Description

Technical Field

[0001] The present invention relates to the technical field of metal detection, and in particular to a metal detection device and method for magnetic materials. Background Art

[0002] In industrial and mining enterprises, belt conveyor metal detectors can detect harmful metals in the belt conveyor system, preventing these metals from damaging the conveyor belt or getting stuck in the machine, thereby reducing the risk of accidents; by timely detecting and eliminating metal impurities, metal detectors help protect downstream equipment from damage, such as crushers, grinders, etc.; metal detectors can monitor harmful metals in the material flow in real time, provide timely warnings and eliminate potential hazards, reduce unexpected downtime and maintenance needs, and thus improve overall production efficiency.

[0003] However, when conveyor belts carry high-grade (≥60%) iron ore and other magnetic materials, the inherent magnetic properties of these materials can generate interference signals, affecting the accuracy of metal detectors. This interference can lead to false alarms or missed detections. The presence of these materials can reduce the sensitivity of metal detectors, diminishing their ability to detect metals. In some cases, the strong magnetic fields of these materials can cause metal detectors to malfunction, limiting their use in certain environments.

[0004] Among existing metal detector technologies, the IB (Induction Balance) metal detector utilizes the induction balance principle and primarily consists of a transmitting coil and a receiving coil. The transmitting coil is installed above the conveyor belt, while the receiving coil is installed below. The electromagnetic field generated by the transmitting coil is affected by metal objects, and the signal captured by the receiving coil is processed to detect the presence of metal. However, this type of metal detector cannot eliminate interference caused by iron ore concentrate, iron ore, and steel cord conveyor belts. Therefore, IB metal detectors are not suitable for use with steel cord conveyor belts, iron ore concentrate, or iron ore. Summary of the Invention

[0005] In view of this, the present invention proposes a metal detection device and method for magnetic materials, aiming to solve the problem that metal impurities in existing magnetic materials are difficult to accurately detect.

[0006] In one aspect, the present invention provides a metal detection device for magnetic materials, comprising: a uniform magnetic field generating device, a belt joint identification unit, a signal processing unit, and an alarm unit; wherein the uniform magnetic field generating device is installed in conjunction with a steel cord conveyor belt that transports magnetic materials, and is used to generate a uniform alternating magnetic field in the peripheral space of the steel cord conveyor belt using an oscillating current, so that the steel cord conveyor belt passes through the alternating magnetic field along its operating path;

[0007] The belt joint identification unit is arranged on the running path of the steel cord conveyor belt, is located at the front end of the uniform magnetic field generating device, and is located below the steel cord conveyor belt, and is used to detect the belt joint signal of the steel cord conveyor belt and transmit it to the signal processing unit;

[0008] The signal processing unit is connected to the uniform magnetic field generating device, and is used to collect the oscillating current signal generated by the uniform magnetic field generating device in real time, and extract the amplitude of the oscillating current signal to construct a background signal; when the steel cord conveyor belt starts to transport magnetic materials and passes through the alternating magnetic field generated by the uniform magnetic field generating device, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic material; when the background signal starts to fluctuate, the initial alarm threshold of metal impurities is set according to the fluctuation amplitude of the background signal; the signal processing unit is also used to generate an alarm trigger signal when the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, thereby prompting that metal impurities are mixed in the magnetic material;

[0009] The signal processing unit is also connected to the belt joint identification unit to receive the belt joint signal sent by the belt joint identification unit, adjust the alarm threshold of metal impurities to be higher than the initial alarm threshold according to the belt joint signal, and restore the alarm threshold of metal impurities to the initial alarm threshold after the belt joint is away from the uniform magnetic field generating device; and generate an alarm trigger signal when the amplitude of the background signal is instantaneously higher than the adjusted alarm threshold to indicate that metal impurities have fallen into the belt joint. The alarm unit is connected to the signal processing unit.

[0010] Furthermore, in the above-mentioned metal detection device for magnetic materials, the uniform magnetic field generating device includes: an oscillating circuit, a first coil and a second coil; wherein the first coil and the second coil are arranged in parallel along the running direction of the steel cord conveyor belt, and the first coil and the second coil are distributed on the upper and lower sides of the steel cord conveyor belt;

[0011] The oscillation circuit is connected to both the first coil and the second coil, and is used to provide an oscillating current to the first coil and the second coil, thereby generating a uniform alternating magnetic field between the first coil and the second coil.

[0012] Furthermore, in the above-mentioned metal detection device for magnetic materials, there are multiple first coils and multiple second coils, and the first coils and the second coils are arranged in a one-to-one correspondence, and each pair of the first coils and the second coils forms a matrix arrangement.

[0013] Furthermore, in the above-mentioned metal detection device for magnetic materials, the uniform magnetic field generating device includes: an oscillation circuit, a third coil and a fourth coil; wherein, the third coil and the fourth coil pass through the steel wire rope conveyor belt in a direction perpendicular to the running path of the steel wire rope conveyor belt, and the third coil and the fourth coil are arranged at a preset distance from front to back along the conveying path of the steel wire rope conveyor belt; the oscillation circuit is connected to both the third coil and the fourth coil to provide an oscillating current to the third coil and the fourth coil, thereby generating a uniform alternating magnetic field between the third coil and the fourth coil.

[0014] Furthermore, in the above-mentioned metal detection device for magnetic materials, when the uniform magnetic field generating device and the steel cord conveyor belt are in a relatively static state, the background signal is a straight line.

[0015] Furthermore, the metal detection device for magnetic materials further includes: a protective cover; wherein the protective cover is arranged outside the uniform magnetic field generating device to protect internal components of the uniform magnetic field generating device from the influence of the external environment.

[0016] Furthermore, in the above-mentioned metal detection device for magnetic materials, the signal processing unit includes: a signal conditioning circuit unit, an ADC sampling circuit unit and an MCU processor circuit unit; wherein the signal conditioning circuit unit is connected to the uniform magnetic field generating device and is used to obtain the amplitude of the oscillating current signal in the uniform magnetic field generating device and construct a background signal for metal impurity detection based on the amplitude;

[0017] The ADC sampling circuit unit is connected to the signal conditioning circuit unit and is used to convert the collected background signal into a digital signal;

[0018] The MCU processor circuit unit is connected to the ADC sampling circuit unit and the belt joint identification unit, and is used for receiving the background signal and the belt joint signal and processing them.

[0019] Furthermore, in the above-mentioned metal detection device for magnetic materials, the alarm unit includes: an alarm output circuit; wherein the input end of the alarm output circuit is connected to the signal processing unit; and the output end of the alarm output circuit is connected to an external iron removal device or warning device.

[0020] Furthermore, the above-mentioned metal detection device for magnetic materials also includes: a human-computer interaction unit; wherein the human-computer interaction unit is connected to the signal processing unit, and is used to display the fluctuation amplitude of the background signal and set the initial alarm threshold of metal impurities, display the alarm output status and the number of alarms.

[0021] The present invention generates a uniform alternating magnetic field on the conveying path of the steel wire rope conveyor belt that transports magnetic materials through a uniform magnetic field generating device, and sets and adjusts the alarm threshold of metal impurities according to the fluctuation amplitude of the background signal caused when the steel wire rope conveyor belt transports the magnetic materials through the alternating magnetic field, thereby avoiding the influence of the interference signal of the magnetic material and the steel wire rope conveyor belt itself on the detection result; since the alternating magnetic field generated by the uniform magnetic field generating device is a uniform magnetic field, the sudden change of the magnetic field will be reduced, thereby reducing the fluctuation of the background signal and effectively suppressing the interference between the steel wire rope conveyor belt and the magnetic material; the signal processing unit adjusts the alarm threshold of metal impurities to higher than the initial alarm threshold according to the received belt joint signal, and generates an alarm trigger signal when the amplitude of the collected background signal exceeds the initial alarm threshold, which on the one hand filters out the false alarm generated by the belt joint, and on the other hand can also effectively detect the metal impurities in the magnetic material to avoid missed alarms.

[0022] On the other hand, the present invention also provides a metal detection method for magnetic materials, using the metal detection device for magnetic materials as described above, comprising:

[0023] The oscillating current signal from the uniform magnetic field generating device is collected in real time, and a background signal is constructed based on the amplitude change of the oscillating current signal. When the steel cord conveyor belt begins to transport magnetic materials and passes through the alternating magnetic field, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the vibration amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic materials. When the background signal begins to fluctuate, an initial alarm threshold for metal impurities is set based on the fluctuation amplitude of the background signal.

[0024] When the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, an alarm trigger signal is generated, indicating that the magnetic material is mixed with metal impurities;

[0025] When a belt joint signal is received, the alarm threshold of metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint is away from the uniform magnetic field generating device, the alarm threshold of metal impurities is restored to the initial alarm threshold; when the amplitude of the background signal exceeds the adjusted alarm threshold, an alarm trigger signal is generated to indicate that metal impurities have fallen into the belt joint, and is sent to the alarm unit for alarm action.

[0026] The metal detection method for magnetic materials provided by the present invention sets the initial alarm threshold of metal impurities according to the fluctuation amplitude of the background signal constructed when the steel wire rope conveyor belt and the magnetic material pass through the alternating magnetic field generated by the uniform magnetic field generating device, and generates an alarm trigger signal when the intensity of the received oscillating current signal exceeds the initial alarm threshold of the metal impurities, indicating that the magnetic material is mixed with metal impurities; and briefly adjusts the alarm threshold of the metal impurities to be higher than the initial alarm threshold according to the received belt joint signal; and generates an alarm trigger signal when the intensity of the received oscillating current signal exceeds the adjusted alarm threshold, indicating that metal impurities have fallen into the belt joint. This method can effectively suppress the interference between the steel wire rope conveyor belt and the magnetic material, thereby realizing the accurate detection of metal impurities in the magnetic material under the working condition that the steel wire rope conveyor belt transports magnetic materials (such as iron ore concentrate and iron ore). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0028] Figure 1 A schematic structural diagram of a metal detection device for magnetic materials provided in an embodiment of the present invention;

[0029] Figure 2 A structural block diagram of a metal detection device for magnetic materials provided in an embodiment of the present invention;

[0030] Figure 3 A schematic structural diagram of a uniform magnetic field generating device in a metal detection device for magnetic materials provided by an embodiment of the present invention;

[0031] Figure 4 Another structural schematic diagram of a uniform magnetic field generating device of a metal detection device for magnetic materials provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] Device Example:

[0034] See Figure 1 and Figure 2 , the metal detection device for magnetic materials of the embodiment of the present invention comprises: a uniform magnetic field generating device 1, a belt joint identification unit 4, a signal processing unit 3 and an alarm unit 5; wherein, the uniform magnetic field generating device 1 is installed in conjunction with the steel cord conveyor belt 2 for transporting magnetic materials, and is used to generate a uniform alternating magnetic field in the peripheral space through which the steel cord conveyor belt 2 passes, so that the steel cord conveyor belt 2 for transporting magnetic materials passes through the alternating magnetic field on its running path; the belt joint identification unit 4 is arranged at a position at the front end of the uniform magnetic field generating device 1 on the running path of the steel cord conveyor belt 2, and is located below the steel cord conveyor belt 2, and is used to detect the belt joint signal of the steel cord conveyor belt 2 and transmit the detected belt joint signal to the signal processing unit 3; the signal processing unit 3 is connected to the uniform magnetic field generating device 1, and is used to collect the oscillating current signal generated by the uniform magnetic field generating device 1 in real time, and extract the amplitude of the oscillating current signal to construct a background signal; when the steel cord conveyor belt 2 starts to transport magnetic materials When the material passes through the alternating magnetic field generated by the uniform magnetic field generating device 1, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel wire rope core conveyor belt 2 and the instantaneous flow rate of the magnetic material; when the background signal begins to fluctuate, the initial alarm threshold of the metal impurities is set according to the fluctuation amplitude of the background signal; the signal processing unit 3 is also used to generate an alarm trigger signal when the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, thereby prompting that metal impurities are mixed in the magnetic material; the signal processing unit 3 is also connected to the belt joint identification unit 4 to receive the belt joint signal sent by the belt joint identification unit 4. When the belt joint signal is received, the alarm threshold of the metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint is away from the uniform magnetic field generating device 1, the alarm threshold of the metal impurities is restored to the initial alarm threshold; and when the amplitude of the background signal instantaneously exceeds the adjusted alarm threshold, an alarm trigger signal is generated to prompt that metal impurities have fallen into the belt joint part;

[0035] The alarm unit 5 is connected to the signal processing unit 3 to receive the alarm trigger signal sent by the signal processing unit 3 and perform an alarm action accordingly.

[0036] Specifically, the uniform magnetic field generating device 1 can be a Helmholtz coil. Preferably, the uniform magnetic field generating device 1 can be composed of an oscillating circuit 10 and several Helmholtz coils, so as to generate an oscillating current and an alternating magnetic field between each Helmholtz coil. The alternating magnetic field can be a sinusoidal alternating magnetic field.

[0037] The magnetic material in this embodiment may include iron ore and iron concentrate of various grades.

[0038] Helmholtz coils can smooth the magnetic field changes experienced by the steel cord conveyor belt 2 transporting magnetic materials as it passes through the coils. The uniform magnetic field of the Helmholtz coil reduces sudden changes in the magnetic field relative to the moving steel cord conveyor belt 2 and the flow of magnetic materials, thereby reducing background signal fluctuations and effectively suppressing interference between the steel cord conveyor belt 2 and the iron ore concentrate.

[0039] It should be noted that the magnetic material in “taking the oscillating current signal when the steel cord conveyor belt 2 and the magnetic material pass through the alternating magnetic field as the background signal” does not include metal impurities.

[0040] The signal processing unit 3 collects the oscillating current signal generated by the uniform magnetic field generating device 1 in real time, and extracts the amplitude of the oscillating current signal to construct a background signal. The fluctuation amplitude of the background signal can be regarded as a curve of the oscillating current amplitude changing with time.

[0041] In this embodiment, when the uniform magnetic field generating device 1 and the steel rope core conveyor belt 2 are in a relatively static state, the background signal is a straight line; when the steel rope core conveyor belt 2 starts to transport magnetic materials and passes through the alternating magnetic field generated by the uniform magnetic field generating device 1, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel rope core conveyor belt 2 and the instantaneous flow rate of the magnetic material.

[0042] In practical applications, the average of the background signal amplitudes can be used as the initial warning threshold. Based on the specific site conditions, this initial alarm threshold can be adjusted upward or downward to accommodate different environmental conditions and requirements. For example, for large magnetic materials or steel cord conveyor belts with large vibration amplitudes, the alarm threshold can be adjusted to a certain range above the initial alarm threshold. This allows for flexible setting of the initial alarm threshold based on the grade of iron ore and iron concentrate, enabling accurate detection of harmful metal impurities in various grades of iron ore and iron concentrate, and even enabling detection of harmful metal impurities (including magnetic and non-magnetic metals) in high-grade (≥60%) iron ore and iron concentrate, with alarm output based on the detection results.

[0043] When the steel cord conveyor belt 2 and the magnetic material pass through the alternating magnetic field generated by the uniform magnetic field generating device 1, the oscillating current amplitude fluctuates. The stronger the magnetism of the magnetic material flow and the greater the vibration amplitude of the steel cord core, the more significant the fluctuation in the oscillating current amplitude. Therefore, the initial alarm threshold for metal impurities is set based on the fluctuation amplitude of the background signal. In this embodiment, the fluctuation amplitude of the background signal is always smaller than the initial alarm threshold, and the magnetic material flow and the steel cord conveyor belt 2 passing through the uniform magnetic field generating device 1 will not trigger an alarm. When metal impurities are mixed into the magnetic material, the fluctuation amplitude of the background signal instantaneously exceeds the initial alarm threshold, triggering an alarm.

[0044] Because the belt joints of the steel cord conveyor belt 2 contain a large amount of metal, a false alarm can be triggered when the belt joint passes through the uniform magnetic field generating device 1, which is unacceptable during production. In this embodiment, the signal processing unit 3 is connected to the belt joint identification unit 4 and can adjust the metal impurity alarm threshold so that the alarm is not triggered when the belt joint passes through the uniform magnetic field generating device 1. The alarm is triggered only when the amplitude of the background signal momentarily exceeds the adjusted alarm threshold when metal falls onto the belt joint.

[0045] The belt joint identification unit 4 can be a photoelectric sensor, a magnetic sensor, a visual sensor or an ultrasonic sensor, which can be installed on the side below the steel wire rope conveyor belt 2 and at the front end of the uniform magnetic field generating device 1 through a bracket. The signal processing unit 3 can dynamically adjust the alarm threshold of metal impurities according to the received belt joint signal, so that the background signal is temporarily lower than the metal alarm threshold, so that the alarm will not be triggered. After the belt joint leaves the rectangular Helmholtz coil, the alarm threshold of metal impurities is restored to the previous initial alarm threshold. At the same time, when metal happens to fall on the belt joint, the amplitude of the background signal will instantly exceed the adjusted alarm threshold, and a trigger alarm signal will be generated. On the one hand, it effectively filters out the false alarms caused by the belt joint. On the other hand, if metal happens to fall on the belt joint, the metal can still be detected and no missed alarm will be generated.

[0046] Continue reading Figure 2 In this embodiment, the signal processing unit 3 includes: a signal conditioning circuit unit 31, an ADC sampling circuit unit 32 and an MCU processor circuit unit 33; wherein the signal conditioning circuit unit 31 is connected to the uniform magnetic field generating device 1, and is used to obtain the amplitude of the oscillating current signal in the uniform magnetic field generating device 1, and construct a background signal for metal detection based on it; the ADC sampling circuit unit 32 is connected to the signal conditioning circuit unit 31, and is used to convert the collected background signal into a digital signal; the MCU processor circuit unit 33 is connected to the ADC sampling circuit unit 32 and the belt joint identification unit 4, and is used to receive the background signal and the belt joint signal and process them.

[0047] Specifically, the signal conditioning circuit unit 31 consists of a peak detection circuit 311, a filter circuit 312, and an amplifier circuit 313. Its function is to obtain the background signal for metal detection. The peak detection circuit 311 is connected to the oscillation circuit 10 to extract the peak value of the oscillating current. The filter circuit 312 is a second-order low-pass filter circuit that filters out high-frequency components from the peak signal. The amplifier circuit 313 is a proportional amplifier circuit that amplifies the low-frequency peak signal to form the final metal detection background signal for transmission to the ADC sampling circuit unit 32. The ADC sampling circuit unit 32 is used to convert the conditioned background signal into a digital signal and provide it to the MCU processor circuit unit 33.

[0048] The MCU processor circuit unit 33 uses an STM32H7B0 or STM32H750 chip, and is responsible for digital signal processing of the background signal and the belt connector signal transmitted from the ADC sampling circuit unit 32, setting an appropriate alarm threshold, and determining whether metal is present.

[0049] Of course, the signal processing unit 3 may also include a housing (not shown); the signal conditioning circuit unit 31, the ADC sampling circuit unit 32, and the MCU processor circuit unit 33 are housed within the housing. The housing is an IP68 waterproof aluminum enclosure with dimensions of 290 mm (width, height, and depth) x 186 mm (height, depth, and width) x 73 mm (height, height, and depth). The touch screen is embedded within the panel of the waterproof aluminum enclosure, and wiring utilizes a waterproof aviation plug.

[0050] In this embodiment, the alarm unit 5 includes: an alarm output circuit; wherein, the input end of the alarm output circuit is connected to the MCU processor circuit unit 33 of the signal processing unit 3, and is used to receive the alarm trigger signal sent by the MCU processor circuit unit 33; the output end of the alarm output circuit is connected to an external iron removal device or warning device, and is used to send an alarm signal when receiving the alarm trigger signal sent by the MCU processor circuit unit 33.

[0051] The alarm output circuit features two output modes to accommodate different operating conditions: passive and active. The passive output utilizes relays, while the active output utilizes solid-state relays. The passive output is used to interlock iron removal equipment such as iron removers and metal separators, while the active output is used to directly drive warning devices such as alarm lights.

[0052] This embodiment may further include: a memory (not shown in the figure); wherein the memory is connected to the signal processing unit 3 and is used to store configuration parameters, historical records and processing results.

[0053] In this embodiment, it also includes: a human-computer interaction unit 6; wherein, the human-computer interaction unit 6 is connected to the signal processing unit 3, and is used to display the fluctuation amplitude of the background signal and set the initial alarm threshold of metal impurities, display the alarm output status and the number of alarms.

[0054] Specifically, the human-computer interaction unit 6 may be a touch screen.

[0055] It can be clearly concluded from the above that the metal detection device for magnetic materials provided in this embodiment generates a uniform alternating magnetic field on the conveying path of the steel cord conveyor belt 2 that transports the magnetic material through the uniform magnetic field generating device 1. The alarm threshold of the metal impurities is set and adjusted according to the fluctuation amplitude of the background signal caused when the steel cord conveyor belt 2 transports the magnetic material through the alternating magnetic field, which can avoid the influence of the interference signal of the magnetic material and the steel cord conveyor belt 2 itself on the detection result; since the alternating magnetic field generated by the uniform magnetic field generating device 1 is a uniform magnetic field, the sudden change of the magnetic field will be reduced, thereby reducing the fluctuation of the background signal and effectively suppressing the interference between the steel cord conveyor belt 2 and the magnetic material; the signal processing unit 3 adjusts the alarm threshold of the metal impurities to be higher than the initial alarm threshold according to the received belt joint signal, and generates an alarm trigger signal when the amplitude of the collected background signal exceeds the initial alarm threshold. On the one hand, it filters out the false alarms generated by the belt joint, and on the other hand, it can also effectively and accurately detect the metal impurities in the magnetic material to avoid missed alarms.

[0056] Combine Figure 2 and Figure 3 In a specific implementation of this embodiment, the uniform magnetic field generating device 1 includes: an oscillation circuit 10, a first coil 11 and a second coil 12; wherein, the first coil 11 and the second coil 12 are arranged parallel to the running direction of the steel cord conveyor belt 2, and the first coil 11 and the second coil 12 are distributed on the upper and lower sides of the steel cord conveyor belt 2; the oscillation circuit 10 is connected to both the first coil 11 and the second coil 12 to provide an oscillating current to the first coil 11 and the second coil 12, thereby generating a uniform alternating magnetic field between the first coil 11 and the second coil 12.

[0057] Preferably, there are multiple first coils 11 and multiple second coils 12, each corresponding to the first coils 11 and the second coils 12. Each pair of first coils 11 and second coils 12 forms a matrix arrangement. Specifically, each first coil 11 is collinearly arranged, and each second coil 12 is collinearly arranged. The spacing between adjacent first coils 11 and adjacent second coils 12 is minimized to reduce detection blind spots.

[0058] More specifically, the first coil 11 and the second coil 12 are rectangular, square, triangular or circular Helmholtz coils.

[0059] Preferably, the first coil 11 and the second coil 12 are rectangular. The rectangular Helmholtz coils are arranged in a matrix and form a whole. The uniformity of the magnetic field will not decrease as the coil size increases, and the detection capability will not be affected as the width of the steel cord conveyor belt 2 increases.

[0060] The uniform magnetic field generating device 1 further includes an oscillating power supply 100 , which supplies power to the oscillating circuit 10 to generate an oscillating current in the first coil 11 and the second coil 12 .

[0061] In this embodiment, the oscillation circuit 10 may be a sinusoidal oscillation circuit, generating a sinusoidal alternating magnetic field in the first coil 11 and the second coil 12. In this embodiment, a significant eddy current effect is generated when non-magnetic metal passes through the rectangular Helmholtz coil, thereby affecting the oscillating current signal and enabling the detection of non-magnetic metal impurities.

[0062] Combine Figure 2 and Figure 4 In another specific implementation of this embodiment, the uniform magnetic field generating device 1 includes: an oscillation circuit 10, a third coil 13 and a fourth coil 14; wherein the third coil 13 and the fourth coil 14 pass through the steel cord conveyor belt 2 in a direction perpendicular to the running path of the steel cord conveyor belt 2, and the third coil 13 and the fourth coil 14 are arranged at a preset distance from each other along the conveying path of the steel cord conveyor belt 2; the oscillation circuit 10 is connected to both the third coil 13 and the fourth coil 14 to provide an oscillating current to the third coil 13 and the fourth coil 14, thereby generating a uniform alternating magnetic field between the third coil 13 and the fourth coil 14.

[0063] The third coil 13 and the fourth coil 14 are rectangular, square, triangular or circular Helmholtz coils. In this embodiment, the oscillation circuit 10 may be a sinusoidal oscillation circuit, forming a sinusoidal alternating magnetic field in the third coil 13 and the fourth coil 14 .

[0064] Each of the above embodiments further includes: a protective cover (not shown in the figure); wherein the protective cover is arranged outside the uniform magnetic field generating device 1 to protect internal components of the uniform magnetic field generating device 1 from the influence of the external environment.

[0065] Specifically, the protective cover is a rectangular or square frame structure, wherein the size of the hollow portion can be determined according to actual conditions, and can pass through the steel cord conveyor belt 2. The protective cover is made of PVC material.

[0066] Method Example:

[0067] The present invention also provides a metal detection method for magnetic materials, comprising:

[0068] The oscillating current signal in the uniform magnetic field generating device 1 is collected in real time, and a background signal is constructed according to the amplitude change of the oscillating current signal; when the steel cord conveyor belt 2 starts to transport magnetic materials and passes through the alternating magnetic field, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic material; when the background signal begins to fluctuate, the initial alarm threshold of the metal impurities is set according to the fluctuation amplitude of the background signal.

[0069] Specifically, when the steel cord conveyor belt 2 and the magnetic material pass through the alternating magnetic field generated by the uniform magnetic field generating device 1 , interference signals are generated, causing changes in the amplitude of the oscillating current.

[0070] During normal operation (i.e., without additional metal interference), signal processing unit 3 continuously collects oscillating current signals from uniform magnetic field generator 1. These signals represent the system's "background" state in the absence of abnormalities. An initial alarm threshold for metal impurities can be set based on historical data and fluctuations in this background signal. This threshold can be set high enough to ensure that normal background signal fluctuations do not trigger an alarm.

[0071] When the amplitude of the background signal momentarily exceeds the initial alarm threshold for metal impurities, an alarm trigger signal is generated, indicating that the magnetic material is mixed with metal impurities. In other words, when abnormal metal impurities pass through, the amplitude of the background signal will significantly exceed the initial alarm threshold, thereby triggering an alarm.

[0072] When a belt joint signal is received, the alarm threshold of metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint moves away from the uniform magnetic field generating device 1, the alarm threshold of metal impurities is restored to the initial alarm threshold; when the amplitude of the background signal exceeds the adjusted alarm threshold, an alarm trigger signal is generated, indicating that metal impurities have fallen into the belt joint, and is sent to the alarm unit 5 for alarm action.

[0073] Specifically, the belt joint increases the fluctuation amplitude of the background signal, which exceeds the alarm threshold and causes the metal detection device to falsely alarm. Therefore, it is necessary to filter out the signal so that the background signal is temporarily lower than the initial alarm threshold so that the alarm will not be triggered. After the belt joint leaves the uniform magnetic field generating device 1, the metal alarm threshold is restored to the previous initial alarm threshold.

[0074] The relevant parts of the method embodiment and the above-mentioned device embodiment can be referenced to each other and will not be repeated here.

[0075] In summary, the present invention can effectively suppress the interference between the steel wire rope conveyor belt 2 and magnetic materials such as iron ore and iron concentrate, so that metal impurities can be accurately and effectively detected when the steel wire rope conveyor belt 2 transports magnetic materials. It can even achieve accurate detection of metal impurities contained in magnetic materials under the working conditions of high-grade (≥60%) magnetic materials (such as iron ore and iron concentrate).

[0076] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A metal detection device for magnetic materials, characterized in that: include: Uniform magnetic field generating device, belt joint A head recognition unit, a signal processing unit and an alarm unit; wherein the uniform magnetic field generating device is installed in conjunction with a steel cord conveyor belt that transports magnetic materials, and is used to generate a uniform alternating magnetic field in the peripheral space where the steel cord conveyor belt passes through by using an oscillating current, so that the steel cord conveyor belt passes through the alternating magnetic field on its running path; The belt joint identification unit is arranged on the running path of the steel cord conveyor belt, and is located in the uniform magnetic field generating The front end of the device is located below the steel cord conveyor belt to detect the belt of the steel cord conveyor belt. Connector signal, and transmit it to the signal processing unit; The signal processing unit is connected to the uniform magnetic field generating device and is used to collect the signal of the uniform magnetic field generating device in real time. an oscillating current signal generated by a device, and extracting the amplitude of the oscillating current signal to construct a background signal; When the wire rope When the core conveyor belt starts to transport magnetic materials and passes through the alternating magnetic field generated by the uniform magnetic field generating device, the background The signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the vibration amplitude of the steel cord conveyor belt and the magnetic material the instantaneous flow rate; when the uniform magnetic field generating device and the steel cord conveyor belt are in a relatively static state, the background signal is a straight line; when the background signal begins to fluctuate, the initial alarm threshold of metal impurities is set according to the fluctuation amplitude of the background signal; the signal processing unit is further used to generate an alarm trigger signal when the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, thereby prompting the mixing of metal impurities into the magnetic material; The signal processing unit is also connected to the belt joint identification unit to receive the belt joint identification unit The belt joint signal sent is used to adjust the alarm threshold of metal impurities to a level higher than the initial alarm threshold according to the belt joint signal. The threshold value is set, and after the belt joint is away from the uniform magnetic field generating device, the alarm threshold value of the metal impurities is restored to the initial value. and generate an alarm trigger signal when the amplitude of the background signal is instantaneously higher than the adjusted alarm threshold. It prompts that metal impurities have fallen into the belt joint; the alarm unit is connected to the signal processing unit.

2. The metal detection device for magnetic materials according to claim 1, characterized in that: The uniform magnetic field generating device comprises: an oscillating circuit, a first coil and a second coil; wherein the first coil and the second coil are arranged in parallel along the running direction of the steel cord conveyor belt, and the first coil and the second coil are distributed on the upper and lower sides of the steel cord conveyor belt; The oscillation circuit is connected to both the first coil and the second coil to provide power to the first coil and the second coil. The two coils are supplied with oscillating current, thereby generating a uniform alternating magnetic field between the first coil and the second coil.

3. The metal detection device for magnetic materials according to claim 2, characterized in that: The first coil and The second coils are multiple, and the first coils and the second coils are arranged in a one-to-one correspondence, each pair of the first coils The first coil and the second coil are arranged in a matrix.

4. The metal detection device for magnetic materials according to claim 1, characterized in that: The uniform magnetic field The device comprises: an oscillating circuit, a third coil, and a fourth coil; wherein the third coil and the fourth coil pass through the steel cord conveyor belt in a direction perpendicular to the running path of the steel cord conveyor belt, and the third coil and the fourth coil are arranged at a preset distance in front and behind along the conveying path of the steel cord conveyor belt; The oscillation circuit is connected to the third coil and the fourth coil to supply power to the third coil and the fourth coil. The four coils are supplied with oscillating currents, thereby generating a uniform alternating magnetic field between the third coil and the fourth coil.

5. The metal detection device for magnetic materials according to claim 1, characterized in that: Also includes: A protective cover; wherein the protective cover is arranged outside the uniform magnetic field generating device to protect the internal components of the uniform magnetic field generating device from the influence of the external environment.

6. The metal detection device for magnetic materials according to claim 1, characterized in that: The signal processing unit includes: a signal conditioning circuit unit, an ADC sampling circuit unit and an MCU processor circuit unit; wherein the signal conditioning circuit unit is connected to the uniform magnetic field generating device and is used to obtain the amplitude of the oscillating current signal in the uniform magnetic field generating device and construct a background signal for metal impurity detection based on the amplitude; The ADC sampling circuit unit is connected to the signal conditioning circuit unit and is used to convert the collected background signal into is a digital signal; The MCU processor circuit unit is connected to the ADC sampling circuit unit and the belt joint identification unit, and is used for receiving the background signal and the belt joint signal and processing them.

7. The metal detection device for magnetic materials according to claim 1, characterized in that: The alarm unit includes: an alarm output circuit; wherein the input end of the alarm output circuit is connected to the signal processing unit; and the output end of the alarm output circuit is connected to an external iron removal device or a warning device.

8. The metal detection device for magnetic materials according to claim 1, characterized in that: Also includes: Human-computer interaction unit; wherein, the human-computer interaction unit is connected to the signal processing unit, and is used to display the fluctuation amplitude of the background signal and set the initial alarm threshold of metal impurities, display the alarm output status and the number of alarms.

9. A metal detection method for magnetic materials, using the metal detector for magnetic materials according to claim 1 The detection device is characterized in that include: The oscillating current signal in the uniform magnetic field generating device is collected in real time, and the amplitude change of the oscillating current signal is detected. Construct background signal; When the steel cord conveyor belt begins to transport magnetic materials and passes through the alternating magnetic field, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the vibration amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic materials. When the background signal begins to fluctuate, the initial alarm threshold for metal impurities is set according to the fluctuation amplitude of the background signal; When the amplitude of the background signal exceeds the initial alarm threshold of the metal impurities, an alarm trigger signal is generated. It shows that the magnetic material is mixed with metal impurities; When the belt joint signal is received, the metal impurity alarm threshold is adjusted to above The initial alarm threshold is set, and after the belt joint moves away from the uniform magnetic field generating device, the alarm threshold of metal impurities is restored to the initial alarm threshold; when the amplitude of the background signal exceeds the adjusted alarm threshold, an alarm trigger signal is generated to prompt that metal impurities have fallen into the belt joint, and is sent to the alarm unit for alarm action.

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