Online radioactivity monitoring system for mineral products

Abstract

This invention relates to the field of radioactivity measurement technology, and particularly to online radioactivity monitoring of mineral products such as coal and iron ore. The invention includes a radioactivity detection module for online radioactivity monitoring, an alarm output module for when the radioactivity intensity of the mineral product exceeds the standard, and a measurement and control module for measurement control. The radioactivity detection module is equipped with a gamma ray detector. The radioactivity detection module is installed above the mineral product conveying line. The entire system also includes a positioning module to locate when the radioactivity intensity of the mineral product exceeds the standard, a nuclide identification module to identify the type of nuclide, and a gamma dose equivalent rate module to measure the dose equivalent rate. This invention solves the problem that existing online radioactivity monitoring systems cannot be used for online radioactivity monitoring of mineral products, and realizes online radioactivity monitoring of mineral products.

Description

Technical Field

[0001] This invention relates to the field of radioactivity measurement technology, and in particular to an online continuous monitoring system for radioactivity in mineral products such as coal and iron ore. Background Technology

[0002] Customs requires all imported mineral products to undergo radioactivity inspection, currently using the standard SN / T 1537 "Radioactivity Inspection Procedures for Imported Mineral Products" issued by the General Administration of Customs. The standard describes the method for radioactivity inspection of bulk cargo shipped by ship: For bulk mineral products shipped by ship, for batches under 1500t, at least four tests are conducted at the beginning of unloading, at 1 / 3 of the total cargo being unloaded, at 2 / 3 of the total cargo being unloaded, and at the end of unloading; for batches over 1500t, measurements are conducted every 500t. At least 50t of mineral products are randomly grabbed from different parts of the cargo surface in the ship's hold using the loading and unloading machinery grabber and transported to the inspection site. These are then piled into a flat stack with a thickness >1m and a top diameter >2m. The detector probe is placed 0.1m from the top surface of the stack to find the highest point of gamma-ray dose equivalent rate. Measurements are repeated five times at the highest point (with 10s intervals), and the average of the five measurements is taken as the gamma-ray dose equivalent rate for that batch of mineral products in that measurement. The highest equivalent rate during the entire testing process is taken as the gamma ray dose equivalent rate of the inspected goods, and radioactivity is measured by intermittent sampling.

[0003] This operation requires manual measurement using a portable radiometric measuring instrument close to the cargo. The measurement points are not continuous, making the operation cumbersome and time-consuming for measuring tens of thousands of tons of bulk cargo. Furthermore, the inability to measure continuously can lead to missed detections. The use of portable instruments also poses a risk of nuclear radiation exposure to the operators.

[0004] To enable continuous and automatic monitoring, online monitoring is required for imported mineral products transported in bulk by sea. According to GB / T 24246 "Monitoring Systems for Radioactive Materials and Special Nuclear Materials", online monitoring systems are divided into pedestrian monitoring systems for personnel radioactivity monitoring, vehicle monitoring systems for container and cargo transported by vehicles, train monitoring systems for container and cargo transported by train, and conveyor belt monitoring systems for baggage and parcel radioactivity monitoring. The standard does not specify online monitoring methods for mineral products transported in bulk by sea. However, for bulk imported mineral products, which are mostly transported by sea and then transported to the storage yard via mineral product conveyor lines, the best method for online monitoring is to install the monitoring system on the mineral product conveyor line and continuously monitor the radioactivity of the mineral products during the transportation process. However, existing online monitoring systems cannot meet the requirements for the structure and operating conditions of mineral product conveyor lines.

[0005] The main reason is that the mineral product conveyor line has the following characteristics: (a) The sides of the mineral product conveyor line are made of belts, rollers, steel frames, etc., which have a shielding effect on radiation. However, the above-mentioned monitoring systems are all installed on both sides of the channel, and the radiation will be shielded by the belts, rollers, steel frames on the sides, affecting the detection efficiency of the monitoring system; (b) The operating speed is fast, reaching 3m / s to 6m / s, while the above-mentioned pedestrian monitoring system requires a speed of 1.2m / s, the vehicle and train monitoring system requires a speed of 2.2m / s, and the conveyor belt requires a speed of 1m / s, none of which can meet the operating speed of the mineral product conveyor line. Summary of the Invention

[0006] To address these issues, the present invention provides an online monitoring system for radioactivity in mineral products, which overcomes the problems of existing portable instruments being cumbersome to operate, time-consuming, and unable to provide continuous monitoring, as well as the inability of existing online monitoring equipment such as those for pedestrians, vehicles, and conveyor belts to meet the requirements for online monitoring of bulk mineral products.

[0007] To achieve the above objectives, the present invention provides an online monitoring system for radioactivity in mineral products, comprising:

[0008] A radioactive detection module is used to detect the radioactivity intensity of mineral products. The radioactive detection module includes one to three gamma radioactive detectors, which are arranged along the width of the mineral product conveyor line. Each gamma ray detector consists of a scintillator, a photoelectric signal detection sensor, and a signal processing circuit. The scintillator is either a plastic scintillator or a sodium iodide scintillator. The total volume of the scintillator is 12L to 52L, and the length of a single scintillator along the running direction of the mineral product conveyor line is 70cm to 140cm. The radioactive detection module must be located above the mineral product conveyor line, with the detection surface of the module facing the mineral product, and the distance between the module and the highest point of the conveyor line is no more than 60cm.

[0009] The alarm output module is used to output an alarm when the radioactivity level of mineral products exceeds the standard.

[0010] The measurement and control module is signal-connected to the radioactivity detection module and the alarm output module. The measurement and control module sends a detection task instruction to the radioactivity detection module, obtains the radioactivity detection information returned by the radioactivity detection module, processes the data based on the returned radioactivity detection information, calculates the measured value of the radioactivity intensity of the reacting mineral product, compares the measured value with a preset radioactivity signal intensity threshold, and if the measured value is greater than the preset threshold, the measurement and control module sends a radioactivity exceedance alarm output task instruction to the alarm output module.

[0011] Furthermore, the radioactivity detection module also includes:

[0012] The environmental gamma radiation background correction detector consists of a scintillator, a photoelectric signal detection sensor, and a signal processing circuit. The photoelectric signal detection sensor outputs environmental gamma radiation detection information. The environmental gamma radiation background correction detector is positioned at a location insensitive to the gamma radioactive rays of the mineral product to detect the intensity of environmental gamma radiation in the environment surrounding the mineral product. The measurement and control module is connected to the environmental gamma radiation background correction detector, sends detection task instructions to the environmental gamma radiation background correction detector, and obtains the detection information returned by the environmental gamma radiation background correction detector. Then, it corrects the detection information returned by the gamma ray detector based on the returned detection information.

[0013] Furthermore, it also includes:

[0014] The positioning module includes a marker, a release device, and a mineral product conveyor line controller. The marker and release device are installed above the mineral product conveyor line. The measurement and control module is signal-connected to the positioning module. When the radioactivity intensity of the mineral product exceeds the standard, the mineral product conveyor line controller issues a stop command for the mineral product conveyor line. At the same time, the measurement and control module sends a signal to the release device, which releases the marker into the mineral product on the mineral product conveyor line to mark the location of the mineral product with excessive radioactivity intensity.

[0015] Furthermore, the positioning module also includes:

[0016] The signal transceiver includes a mobile signal transceiver and a fixed signal transceiver. The mobile signal transceiver is installed in the marker of the positioning module. When the radioactivity of the mineral product exceeds the standard, it is released into the mineral product on the mineral product conveying line along with the marker. The fixed signal transceiver is fixed at any position within the coverage area of ​​the signal transmission and reception. The mobile signal transceiver and the fixed signal transceiver can transmit and receive signals to each other.

[0017] Furthermore, the positioning module can be designed as follows:

[0018] The positioning module includes a speed sensor, a timing sensor, and a controller for the mineral product conveyor line. The control module is signal-connected to the positioning module. When the radioactivity level of the mineral product exceeds the standard, the controller for the mineral product conveyor line issues a stop command for the mineral product conveyor line. At the same time, the timing sensor starts timing, and the speed sensor starts measuring the speed in real time. The distance the mineral product conveyor line moves is calculated by integrating the product of speed and time to mark the location of the mineral product with excessive radioactivity.

[0019] Furthermore, it also includes:

[0020] The gamma dose equivalent rate measurement module has a gamma detection probe and is located above the mineral product conveying line. When the radioactivity intensity of the mineral product exceeds the standard, the gamma dose equivalent rate measurement module is used to measure the gamma dose equivalent rate in the mineral product.

[0021] Furthermore, it also includes:

[0022] The moving mechanism, connected to the gamma dose equivalent rate measurement module, is configured such that the gamma dose equivalent rate measurement module reciprocates at least in the width direction of the mineral product conveying line, so that the gamma dose equivalent rate measurement module can perform gamma dose equivalent rate measurement at any position in the width direction of the mineral product conveying line, and can also reciprocate in the vertical direction, so that gamma dose equivalent rate measurement can be performed at a set distance above the mineral product;

[0023] Furthermore, it also includes:

[0024] The gamma nuclide identification module analyzes the energy characteristics of radionuclides in mineral products when the radioactivity level exceeds the standard, and provides information on the radionuclides in the mineral products.

[0025] Furthermore, it also includes:

[0026] A mineral product height limiting device is equipped with a height limiting and leveling rod, which is arranged along the running direction of the mineral product conveyor line, located upstream of the radioactivity detection module and above the mineral product conveyor line, and performs height leveling on mineral products that exceed the height limiting and leveling rod.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention's online radioactivity monitoring system for mineral products, with the radioactivity detection module located above the mineral product conveyor line, solves the problem that existing pedestrian monitoring systems, vehicle monitoring systems, train monitoring systems, and conveyor belt monitoring systems installed on the side affect detection efficiency; the length of the scintillator of the gamma ray detector along the running direction of the mineral product conveyor line is determined to be 70cm to 140cm, solving the problem that existing systems for online radioactivity monitoring cannot adapt to the high speed of the mineral product conveyor line; at the same time, considering the operating conditions of the mineral product conveyor line and the measurement requirements of SN / T 1537 "Radioactivity Inspection Procedure for Imported Mineral Products", a positioning module, a gamma dose equivalent rate measurement module, a moving mechanism, a gamma nuclide identification module, and a mineral product height limiting device are added, solving the problem that existing online radioactivity monitoring systems cannot adapt to the operating conditions of the mineral product conveyor line, thus enabling online radioactivity monitoring of mineral products. Attached Figure Description

[0028] Figure 1This is a system block diagram of the online radioactivity monitoring system for mineral products according to an embodiment of the present invention;

[0029] Figure 2 This is a three-dimensional structural schematic diagram of the online radioactivity monitoring system for mineral products according to an embodiment of the present invention;

[0030] Figure 3 This is a front view (viewed in the direction of the mineral product conveyor line) of the structure of the online radioactive monitoring system for mineral products according to an embodiment of the present invention.

[0031] Figure 4 This is a top view schematic diagram of the structure of the online radioactive monitoring system for mineral products according to an embodiment of the present invention;

[0032] Figure 5 This is a left-side view of the structure of the online radioactivity monitoring system for mineral products according to an embodiment of the present invention;

[0033] Figure 6 This is a control logic diagram of the online radioactivity monitoring system for mineral products according to an embodiment of the present invention; Detailed Implementation

[0034] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0035] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0036] It should be noted that, unless otherwise emphasized, in the description of the present invention, the terms "upper," "lower," "inner," "outer," etc., indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0037] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] Please see Figures 1 to 6As shown, the specific implementation of the ship ballast water radioactivity measurement system of the present invention is as follows:

[0039] The radioactivity detection module (4) is used to detect the radioactivity intensity of the mineral product (2). The radioactivity detection module consists of a gamma radioactivity detector.

[0040] Bulk mineral products are transported to the storage yard using a mineral product conveyor line. The conveyor line (1) has a V-shaped belt (1-1) with the mineral products wrapped by the belt (1-1) on the side. There are also auxiliary structures such as rollers (1-2) and steel frames (1-3) on the side. The mineral products (2) are inside the belt (1-1). Since the radiation will be shielded by the belt, rollers, steel frames, etc. on the side, the detection efficiency will be affected. Therefore, the radioactive detection module (4) must be located above the mineral product conveyor line (1). In this embodiment of the invention, a mounting bracket (3) is provided, which is designed as a gantry structure, consisting of a column (3-1) and a crossbeam (3-2). The crossbeam (3-1) spans across the mineral product conveyor line (1). The radioactive detection module (4) is connected to the crossbeam (3-2) of the mounting bracket (3), and the detection surface (4-1) of the radioactive detection module (4) faces the mineral products (2).

[0041] The belt (1-1) of the mineral product conveyor line is V-shaped. The depth of the V-shape of the belt varies for different mineral product conveyor lines, generally between 20cm and 70cm. Therefore, in order to ensure that the distance between the detection surface (4-1) and the tested mineral product (2) is within the effective detection range of the radioactive detection module (4), generally within 80cm, the distance between the detection surface (4-1) of the radioactive detection module (4) and the mineral product conveyor line (1) is no more than 60cm. It should be noted that the closer the radioactive detection module (4) is to the mineral product conveyor line (1), the better the detection effect. However, the operating conditions of the mineral product conveyor line must be considered, namely, vibration causing belt fluctuation and unevenness and unevenness of the mineral products loaded on the belt. Therefore, the radioactive detection module (4) needs to maintain a safe distance from the mineral product (2). In this embodiment, the distance between the detection surface (4-1) of the radioactive detection module (4) and the mineral product conveyor line is 20cm.

[0042] It should be noted that the present invention emphasizes that the radioactive detection module (4) must be placed above the mineral product conveying line (1). Therefore, the structure of the mounting bracket (1) is only to describe a way of placing the radioactive detection module above the mineral product conveying line (1). In practical applications, other methods can be used, such as hoisting or other radioactive detection module (4) installation methods with the same effect.

[0043] Radioactive rays are generally classified into four types: alpha, beta, gamma, and neutron. Alpha and beta rays have weak penetrating power and short propagation distances in air; therefore, they are typically measured using surface contamination meters, which will not be elaborated upon in this invention. Gamma rays are common, and most mineral products contain natural gamma radioactive nuclides such as radium-226, thorium-232, and potassium-40. Therefore, gamma rays in mineral products are a primary target for radioactive monitoring. Consequently, the radioactive detector in the radioactive monitoring module is a gamma ray detector (4-2), composed of a scintillator, a photoelectric signal detection sensor, and a signal processing circuit. The scintillator is either a plastic scintillator or a sodium iodide scintillator. The principle and method of the gamma ray detector are existing conventional radioactive monitoring methods and will not be elaborated upon here.

[0044] For gamma ray monitoring of mineral products (2) on mineral product conveying line (1), the main considerations are the depth of V-shaped belt (1-1), the running speed of mineral product conveying line (1) and the width of mineral product conveying line (1). The main difference between this and the online radiometric monitoring system in GB / T 24246 "Monitoring System for Radioactive Substances and Special Nuclear Materials" is the volume and arrangement of the scintillator.

[0045] Generally, the depth of the V-belt (11) is 20cm to 70cm; the running speed of the line (1) is 3m / s to 6m / s; and the width of the mineral product conveying line (1) is 1.2m to 2.6m.

[0046] In order to achieve full coverage of radioactive detection across the width of the mineral transport line (1), one to three gamma-ray detectors are set up along the width of the mineral transport line (1). Furthermore, when the width of the mineral transport line (1) is less than 1.5m, one gamma-ray detector can be considered; when the width of the mineral transport line (1) is between 1.5m and 2.2m, two gamma-ray detectors can be considered; and when the width of the mineral transport line (1) is more than 2.2m, three gamma-ray detectors can be considered.

[0047] The operating speed of the mineral product conveyor line (1) is 3m / s to 6m / s. Currently, the radioactivity monitoring of mineral products transported by truck adopts the method of vehicle radioactivity monitoring system in the standard GB / T 24246 "Radioactive Materials and Special Nuclear Materials Monitoring System". The scintillator volume of the gamma ray detector generally used in the vehicle radioactivity monitoring system is 25L, and the length dimension of the vehicle in the direction of travel is 50cm. The vehicle radioactivity monitoring system requires the vehicle to travel at a speed of 2.2m / s.

[0048] The formula for calculating the detection limit of a gamma-ray detector is as follows:

[0049]

[0050] in:

[0051] K: Confidence probability

[0052] R: Detection efficiency, s -1 / Bq

[0053] Nb: Average background count of the detector, s -1

[0054] Nm: Average reference source count of the detector, s -1

[0055] t b Background measurement time, s

[0056] t m Sample measurement time, s

[0057] t: Measurement time. Generally, the background measurement time and the sample measurement time are the same, so they are both denoted as t.

[0058] It is evident that the detection limit of a gamma-ray detector is related to the detection efficiency R, the detector's background count Nb, and the measurement time t. Since the detection efficiency R and background count Nb of a gamma-ray detector are constant, the measurement time t for online monitoring is related to the operating speed of the mineral conveyor line (1) and the length of the scintillator along the operating direction. Given a constant operating speed of the mineral conveyor line, according to v=s / t, the longer the length of the scintillator along the operating direction, the longer the measurement time will be.

[0059] The vehicle radioactivity monitoring system requires a vehicle speed of 2.2 m / s and a scintillator length of 50 cm along the vehicle's direction of travel. It can be calculated that, to achieve the same effect as the vehicle radioactivity monitoring system in monitoring the radioactivity of mineral products, when the speed of the mineral product conveyor line (1) is 3 m / s to 6 m / s, the length of the scintillator along the direction of travel of the mineral product conveyor line is 70 cm to 140 cm. This range can meet the requirements of most mineral product conveyor lines. Of course, if there are special requirements for the speed of the mineral product conveyor line, this method can be used to extrapolate.

[0060] In practical applications, for online monitoring systems of mineral products, since the volume of a single gamma ray detector and the number of gamma ray detectors are matched, as long as they can cover the width of the mineral product conveying line (1), the volume of a single gamma ray detector can be reduced while the number of gamma ray detectors can be increased, or the volume of a single gamma ray detector can be increased while the number of gamma ray detectors can be reduced. Considering the detection range and the cost of the scintillator, this invention limits the total volume of the scintillator of all gamma ray detectors (4-2) in the entire system to 14L to 52L.

[0061] In practical applications, most mineral product conveyor lines have a width of 1.8m to 2.2m and a speed of 3.5m / s to 4.5m / s. In this embodiment, two gamma ray detectors (4-2) are provided. The scintillator volume of each gamma ray detector (4-2) is 15L, the total volume is 30L, and the length along the running direction of the mineral product conveyor line is 100cm. This configuration can meet the width and speed requirements of most mineral product conveyor lines in practical applications and is a typical configuration for the practical application of this invention.

[0062] It should be noted that in the monitoring of radioactivity in mineral products, due to the need for counter-terrorism and other purposes related to the smuggling of nuclear materials, it is sometimes necessary to measure neutron rays. Therefore, a neutron ray detector can be added to the system of this invention. Since the principle and method of the neutron ray detector are conventional technical means, they will not be described in detail here.

[0063] The alarm output module (5) is used to output an alarm when the radioactivity intensity of mineral products exceeds the standard. Typically, the alarm output can be equipped with an audible and visual alarm indicator (5-1).

[0064] Furthermore, since this invention is for online continuous monitoring, when the radioactivity of the mineral products exceeds the standard, the mineral product conveying line should be stopped. Therefore, the alarm output module (5) can send the alarm signal to the control system of the mineral product conveying line. When the control system of the mineral product conveying line receives the alarm signal, it can control the mineral product conveying line to stop. Since the mineral product conveying line and its control system are not the subject of this invention, they will not be described in detail here.

[0065] The measurement and control module (6) is connected to the radioactive detection module (4) and the alarm output module (5) by signal. The measurement and control module (6) sends a detection task instruction to the radioactive detection module (4), obtains the radioactive detection information returned by the radioactive detection module (4), performs data processing based on the returned radioactive detection information, calculates the measured value of the radioactive intensity of the reaction mineral product, compares the measured value with the preset radioactive ray signal intensity threshold, and if the measured value is greater than the preset threshold, the measurement and control module sends a radioactive over-standard alarm output task instruction to the alarm output module (5).

[0066] Since bulk mineral products are typically transported by ship in quantities of tens of thousands of tons, the process of transporting them to the storage yard via conveyor lines often takes tens of hours. For gamma-ray measurements, the presence of natural radionuclides and cosmic rays in the environment means that even if the mineral product itself does not contain radionuclides, the gamma-ray detector (4-2) will still detect gamma rays from the environment. In the field of radioactivity measurement, this is generally referred to as the environmental gamma radiation background value, or simply the background value. Although lead plates can be added to the non-detection surface of the gamma-ray detector (4-2) for shielding, it cannot completely shield it. Therefore, the actual measured value by the gamma-ray detector (4-2) includes the background value. When calculating whether the radioactivity intensity of the mineral product exceeds the standard, the background value needs to be deducted. Furthermore, the background value contributed by cosmic rays fluctuates greatly due to the influence of sunrise and sunset, and is not constant; it is often higher during the day and lower at night. High on sunny days and low on cloudy days, therefore, in order to make the measurement more accurate, the present invention adds an environmental gamma radiation background correction module (4-3) to the radiometric detection module (4). It is also composed of a scintillator, a photoelectric signal detection sensor, and a signal processing circuit. The photoelectric signal detection sensor outputs environmental gamma radiation detection information. The environmental gamma radiation background correction module (4-3) is arranged at a position where the gamma radioactive rays of the mineral product cannot be detected, in order to detect the intensity of environmental gamma radiation in the environment surrounding the mineral product. The measurement and control module (6) is signal-connected to the environmental gamma radiation background correction module (4-3), sends a detection task instruction to the environmental gamma radiation background correction module (4-3), and obtains the detection information returned by the environmental gamma radiation background correction module. Then, the detection information returned by the gamma ray detector is corrected according to the returned detection information.

[0067] In this embodiment, the environmental gamma radiation background correction module (4-3) uses a 0.5L plastic scintillator. In order to reduce the impact of radioactive nuclides in mineral products on the environmental gamma radiation background correction module (4-3), radiation shielding material needs to be added to the environmental gamma radiation background correction module (4-3), generally lead plate shielding. The gamma ray detector of the environmental gamma radiation background correction module can also use other types of sensors, such as sodium iodide, GM counter tube, etc.

[0068] The practical applications of the environmental gamma radiation background correction module (4-3) are as follows:

[0069] The environmental gamma radiation background correction module (4-3) and the gamma ray detector (4-2) measure synchronously. When the mineral product conveying line (1) is not started, the environmental gamma radiation background correction module (4-3) measures a background value of Nb1, and the gamma ray detector (4-2) measures a background value of Nb2. The gamma ray detector (4-2) sets the threshold value of radioactivity exceeding the standard to be n times the background value Nb2, and then the alarm threshold AL = n * Nb2. Under the same environmental gamma radiation background, the ratio of the background values ​​of the environmental gamma radiation background correction module (4-3) and the gamma ray detector (4-2) is k = Nb1 / Nb2. Since the structure and circuit of the environmental gamma radiation background correction module (4-3) and the gamma ray detector (4-2) are relatively fixed, their ratio k is relatively fixed when the environmental radiation background fluctuates.

[0070] After the mineral product conveying line (1) is started, the system begins to monitor the radioactivity of the mineral products, while the environmental gamma radiation background correction module (4-3) continues to monitor the environmental gamma radiation background. The gamma ray detector (4-2) can then correct its background value and alarm threshold in real time based on the k value. Real-time background value correction for the gamma ray detector (4-2): Nb2 = Nb1 / k; Real-time alarm threshold correction: AL = n*Nb2 = n*Nb1 / k;

[0071] In this way, the system can correct the alarm threshold in real time based on the measurement value of the gamma nuclear radiation background correction module (43), which can reduce false alarms and missed alarms of excessive radioactivity in mineral products.

[0072] During the monitoring of radioactivity in mineral products, the mineral product conveying line is in continuous operation. After the alarm is triggered when the radioactivity intensity of the mineral product exceeds the standard, the system can output a signal to the control system of the mineral product conveying line (1) through the alarm output module (5) to stop the mineral product conveying line. However, due to the delay of the output signal and the inertia of the mineral product conveying line, the mineral product conveying line cannot stop immediately after receiving the output signal from the alarm output module (5), but instead moves forward for a distance. Therefore, a positioning device is needed to determine the accurate location of the mineral product with excessive radioactivity intensity.

[0073] The positioning module (7) of the present invention consists of a marker, a release device and a mineral product conveyor line controller. The marker and the release device are installed above the mineral product conveyor line (1). There are many types of release devices, which are existing conventional technologies and will not be described in detail here. In this embodiment, a push-pull electromagnet is used. The structure is simple and the response is fast. It is often used in drone airdrops and will not be described in detail here. The marker can be a flexible object, such as a water bag, so that it will not bounce around due to collision when released onto the mineral product. The measurement and control module (6) is connected to the positioning module (7) by signal. When the radioactivity of the mineral product exceeds the standard, the mineral product conveyor line controller issues a stop command for the mineral product conveyor line. At the same time, the measurement and control module sends a signal to the release device, which releases the marker into the mineral product on the mineral product conveyor line (1). Even if the mineral product moves due to the inertia of the mineral product conveyor line (1), it will move with the marker. Therefore, as long as the marker is found, the location of the mineral product with excessive radioactivity can be determined.

[0074] In order to quickly locate the marker, the present invention adds a signal transceiver module (8), including a mobile signal transceiver and a fixed signal transceiver. The mobile signal transceiver is installed in the marker of the positioning module (7). When the radioactivity of the mineral product exceeds the standard, it is released together with the marker into the mineral product (2) on the mineral product conveying line (1). The fixed signal transceiver is fixed at any position within the coverage area of ​​the signal transmission and reception. The fixed signal transceiver sends signal A, the mobile signal transceiver receives signal A and returns signal B, and the fixed signal transceiver receives signal B. In this embodiment, signal A and signal B use electromagnetic waves, whose propagation speed v is equal to the speed of light and propagates in a straight line. Based on the time difference t between receiving signal A and returning signal B, the distance and position of the marker can be calculated according to s=vt. The fixed signal transceiver is connected to the measurement and control module (6) and sends the calculated distance and position value of the marker to the measurement and control module (6).

[0075] The positioning module mainly solves the problem that the radioactive material cannot be found due to inertial movement when the mineral product conveyor line (1) stops due to excessive radioactivity alarm. Therefore, as long as the distance moved from the time the mineral product conveyor line (1) receives the stop command until it stops completely, the radioactive source can be located. According to the principle that distance equals speed multiplied by time, the positioning device can also be designed as follows: including a speed sensor of the mineral product conveyor line, a timing sensor, and a controller of the mineral product conveyor line. The control module is connected to the positioning module. When the radioactivity intensity of the mineral product exceeds the standard, the controller of the mineral product conveyor line issues a stop command for the mineral product conveyor line. At the same time, the timing sensor starts timing, and the speed sensor starts measuring the speed in real time. The distance moved by the mineral product conveyor line is calculated by integrating the product of speed and time to mark the position of the mineral product with excessive radioactivity intensity.

[0076] In practical applications, in addition to monitoring whether the radioactivity of mineral products exceeds the standard, it is also necessary to further measure the gamma dose equivalent rate to determine the radioactivity level of mineral products according to the detection results in SN / T 1537 "Inspection Procedure for Radioactivity of Imported Mineral Products". In the past, handheld gamma dose equivalent rate meters were used for measurement. According to the requirements of SN / T 1537 "Inspection Procedure for Radioactivity of Imported Mineral Products", at least 5 measurements need to be taken at a distance of 0.1m from the mineral product, each lasting 10s. However, the gamma ray detector (4-2) mentioned above is mainly used for online real-time monitoring and cannot meet the measurement requirements of gamma dose equivalent rate. Therefore, this invention adds a gamma dose equivalent rate measurement module (9). The gamma dose equivalent rate measurement module (9) has a gamma ray detection probe (91). The gamma dose equivalent rate measurement module is located above the mineral product conveying line. When the radioactivity intensity of the mineral product exceeds the standard, the gamma dose equivalent rate measurement module is used to measure the gamma dose equivalent rate in the mineral product. The measurement principle and method of gamma dose equivalent rate are existing mature technologies and will not be described in detail here.

[0077] The gamma dose equivalent rate measurement module (9) needs to measure mineral products with excessive radioactivity, according to SN / T 1537 "Regulations for Radioactive Inspection of Imported Mineral Products" requires that the gamma dose equivalent rate measurement module (9) needs to be statically measured relative to the mineral product. Therefore, after the mineral product conveyor line stops, the gamma ray detection probe of the gamma dose equivalent rate measurement module (9) needs to be 0.1m away from the mineral product for measurement. As mentioned above, when the radioactivity intensity of the mineral product exceeds the standard, the alarm output module (5) can output a signal to stop the mineral product conveyor line (1). However, due to inertia and other reasons, the mineral product conveyor line (1) will continue to move forward a distance L. This distance L is related to the speed of the mineral product conveyor line (1), the quality of the mineral product, etc. Therefore, the gamma dose equivalent rate measurement module (9) needs to be installed at a certain position downstream of the radioactive ray detection module (4) along the running direction of the mineral product conveyor line (1). This position is consistent with the distance L that the mineral product conveyor line (1) will continue to move forward. It can be found through testing that since the gamma dose equivalent rate measurement module (9) is 0.1m away from the mineral product, its measurement range is limited. Therefore, the present invention adds a moving mechanism ( 10) The gamma dose equivalent rate measurement module (9) is installed on the moving mechanism (10). The moving mechanism can make the gamma dose equivalent rate measurement module reciprocate at least in the width direction of the mineral product conveying line (1) so that the gamma dose equivalent rate measurement module can perform gamma dose equivalent rate measurement at any position in the width direction of the mineral product conveying line (1). It can also reciprocate in the vertical direction so that a distance can be set above the mineral product to perform gamma dose equivalent rate measurement. In this embodiment, the moving mechanism adopts two closed synchronous belt linear modules. The synchronous belt linear module (10-1) runs along the width direction of the mineral product conveying line (1), and the synchronous belt linear module (10-2) runs in the direction perpendicular to the mineral product conveying line (1). The vertical positioning can be achieved by a distance sensor or mechanical device to ensure the distance between the gamma dose equivalent rate measurement module (9) and the mineral product. Of course, the moving mechanism can also be other linear modules. Their structures are all existing mature technologies, which will not be described in detail here.

[0078] Although the mineral product conveying line (1) continues to move forward a relatively fixed distance L due to inertia and other reasons when it stops, in reality, due to the fluctuation of the speed of the mineral product conveying line (1) and the uneven distribution of the mineral product quality in the mineral product conveying line (1), there are errors in the moving distance L before and after each stop. In order to more accurately locate the mineral product with excessive radioactivity, the moving mechanism (10) in this embodiment adds another synchronous belt linear module (10-3), whose running direction is along the running direction of the mineral product conveying line (1). In this way, the gamma dose equivalent rate measurement module (9) can move to the position of the mineral product with excessive radioactivity according to the positioning module (7) along the running direction of the mineral product conveying line (1), or it can scan and measure along the running direction of the mineral product conveying line (1) on its own. According to the measurement values ​​of the gamma dose equivalent rate measurement module (9) at different points, the position of the maximum measurement value is determined as the position of the mineral product with excessive radioactivity.

[0079] Since gamma rays in mineral products generally originate from natural gamma radioactive nuclides such as radium-226, thorium-232, and potassium-40, and in order to combat the smuggling of radioactive sources or terrorist incidents, it is also necessary to monitor artificial nuclides, such as the common cesium-137 and cobalt-60. For more accurate monitoring, it is often necessary to identify the nuclides exceeding the gamma radiation limit in mineral products to determine whether they are natural or artificial nuclides. Furthermore, it is necessary to identify the specific nuclide, so that different treatments and protections can be taken for different nuclides. For this reason, this system also includes a gamma nuclide identification module (11). When the radioactivity intensity of mineral products exceeds the limit, the energy characteristics of the radioactive nuclides in the mineral products are analyzed to provide information on the radioactive nuclides in the mineral products. Nuclide identification is generally based on the energy of the radioactive nuclides. The principle and method are conventional technologies in this field and will not be elaborated here.

[0080] Mineral products are generally placed on the mineral product conveying line (1) by grab bucket, which will cause the mineral products to be unevenly distributed on the mineral product conveying line (1), with ups and downs. Sometimes the height of the mineral products will exceed the safe height. In order to protect the entire online radioactive monitoring system, the present invention adds a mineral product height limiting device (12) and configures a height limiting leveling rod (12-1) to be arranged along the running direction of the mineral product conveying line, located upstream of the radioactive detection module and above the mineral product conveying line, and to level the height of the mineral products (2) that exceed the height limiting leveling rod (12-1).

[0081] The logic of this invention is as follows:

[0082] The gamma ray detector (4-2) and the gamma radiation background correction module (4-3) collect background values. When unloading is required, the mineral product conveying line (1) is started. The gamma ray detector (4-2) monitors the radioactivity intensity level of the mineral product (2) in real time. The gamma radiation background correction module (4-3) can correct the measured value of the gamma ray detector (4-2) in real time.

[0083] When the radioactivity of a mineral product exceeds the standard, the positioning module (7) immediately releases a marker to achieve positioning, the alarm output module (5) outputs an alarm prompt, and at the same time, outputs a signal to the control system of the mineral product conveying line (1) to stop the mineral product conveying line (1). The signal transceiver module (8) can obtain the specific location of the marker, and the staff can quickly find the marker based on the information from the signal transceiver module (8) so as to further process the mineral product with excessive radioactivity.

[0084] The gamma dose equivalent rate measurement module (9) moves on the moving mechanism (10) to measure the gamma dose equivalent rate in areas where the radioactivity intensity of mineral products exceeds the standard.

[0085] The gamma nuclide identification module (11) performs dynamic identification during measurement by the gamma ray detector (4-2) or static identification during measurement by the gamma dose equivalent rate measurement module (9).

[0086] When the radioactivity level of a mineral product exceeds the standard, on-site operators will conduct re-inspection or return the mineral product based on the measurement information.

[0087] The online radioactive monitoring system for mineral products of the present invention, wherein the radioactive detection module (4) must be located above the mineral product conveyor line (1), solves the problem that the existing pedestrian monitoring system, vehicle monitoring system, train monitoring system and conveyor belt monitoring system used for online radioactive monitoring are installed on the side and affect the detection efficiency; the length of the scintillator of the gamma ray detector (4-2) along the running direction of the mineral product conveyor line is determined to be 70cm to 140cm, which solves the problem that the existing system used for online radioactive monitoring cannot adapt to the working conditions due to the high speed of the mineral product conveyor line; at the same time, a positioning module (7) is added for the continuous and inertial operation conditions of the mineral product conveyor line, so that it can be located when the radioactive intensity exceeds the standard; in addition, a gamma dose equivalent rate measurement module (9) and a moving mechanism (10) are added to meet the requirement of gamma dose equivalent rate measurement in SN / T1537 "Radioactive Inspection Procedure for Imported Mineral Products"; in order to more accurately handle and protect against events where the radioactive intensity exceeds the standard, a gamma nuclide identification module (11) is added; in order to ensure the safety of the system, a mineral product height limit device (12) is added to address the uneven stacking of mineral products on the mineral product conveyor line. This invention solves the problem that existing online radioactivity monitoring systems cannot adapt to the working conditions of mineral product conveying lines, thus making them unsuitable for online radioactivity monitoring of mineral products, and realizes online radioactivity monitoring of mineral products.

[0088] In practical applications, video surveillance can be added to achieve real-time monitoring of the mineral product conveying line, and host computer monitoring software can be added to achieve real-time display of measurement data and status, as well as data storage. These are all existing conventional technologies and methods, and will not be elaborated on here.

[0089] The technical solution of the present invention has been described in conjunction with the embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions resulting from such changes or substitutions will all fall within the scope of protection of the present invention.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An online radioactivity monitoring system for mineral products, characterized in that, include: A radioactive detection module is used to detect the radioactivity intensity of mineral products. The radioactive detection module includes one to three gamma radioactive detectors, which are arranged along the width of the mineral product conveyor line. Each gamma ray detector consists of a scintillator, a photoelectric signal detection sensor, and a signal processing circuit. The scintillator is either a plastic scintillator or a sodium iodide scintillator. The total volume of the scintillator is 14L to 52L, and the length of a single scintillator along the running direction of the mineral product conveyor line is 70cm to 140cm. The radioactive detection module must be located above the mineral product conveyor line, with the detection surface of the module facing the mineral product, and the distance between the module and the highest point of the conveyor line not exceeding 60cm. The alarm output module is used to output an alarm when the radioactivity level of mineral products exceeds the standard. The measurement and control module is signal-connected to the radioactivity detection module and the alarm output module. The measurement and control module sends a detection task instruction to the radioactivity detection module, obtains the radioactivity detection information returned by the radioactivity detection module, processes the data based on the returned radioactivity detection information, calculates the measured value of the radioactivity intensity of the reacting mineral product, compares the measured value with a preset radioactivity signal intensity threshold, and if the measured value is greater than the preset threshold, the measurement and control module sends a radioactivity exceedance alarm output task instruction to the alarm output module.

2. The online radioactivity monitoring system for mineral products according to claim 1, characterized in that, The radioactivity detection module also includes: The environmental gamma radiation background correction detector consists of a scintillator, a photoelectric signal detection sensor, and a signal processing circuit. The photoelectric signal detection sensor outputs environmental gamma radiation detection information. The environmental gamma radiation background correction detector is positioned at a location insensitive to the gamma radioactive rays of the mineral product to detect the intensity of environmental gamma radiation in the environment surrounding the mineral product. The measurement and control module is connected to the environmental gamma radiation background correction detector, sends detection task instructions to the environmental gamma radiation background correction detector, and obtains the detection information returned by the environmental gamma radiation background correction detector. Then, it corrects the detection information returned by the gamma ray detector based on the returned detection information.

3. The online radioactivity monitoring system for mineral products according to any one of claims 1 to 2, characterized in that, Also includes: The positioning module includes a marker, a release device, and a mineral product conveyor line controller. The marker and release device are installed above the mineral product conveyor line. The measurement and control module is signal-connected to the positioning module. When the radioactivity level of the mineral product exceeds the standard, the mineral product conveyor line controller issues a stop command for the mineral product conveyor line. At the same time, the measurement and control module sends a signal to the release device, which releases the marker into the mineral product on the mineral product conveyor line to mark the location of the mineral product with excessive radioactivity.

4. The online radioactivity monitoring system for mineral products according to claim 3, characterized in that, The positioning module further includes: The signal transceiver includes a mobile transceiver and a fixed transceiver. The mobile transceiver is installed in the marker of the positioning module. When the radioactivity of the mineral product exceeds the standard, it is released into the mineral product on the mineral product conveying line along with the marker. The fixed transceiver is fixed at any position within the coverage area of ​​the signal transmission and reception. The mobile transceiver and the fixed transceiver can transmit and receive signals to each other.

5. The online radioactivity monitoring system for mineral products according to any one of claims 1 to 2, characterized in that, Also includes: The positioning module includes a speed sensor, a timing sensor, and a controller for the mineral product conveyor line. The control module is signal-connected to the positioning module. When the radioactivity level of the mineral product exceeds the standard, the controller issues a stop command for the mineral product conveyor line. At the same time, the timing sensor starts timing, and the speed sensor starts measuring the speed in real time. The distance the mineral product conveyor line moves is calculated by integrating the product of speed and time to mark the location of the mineral product with excessive radioactivity.

6. The online radioactivity monitoring system for mineral products according to any one of claims 1 to 2, characterized in that, Also includes: The gamma dose equivalent rate measurement module has a gamma detection probe and is located above the mineral product conveying line. When the radioactivity intensity of the mineral product exceeds the standard, the gamma dose equivalent rate measurement module is used to measure the gamma dose equivalent rate in the mineral product.

7. The online radioactivity monitoring system for mineral products according to claim 6, characterized in that, Also includes: The moving mechanism, connected to the gamma dose equivalent rate measurement module, is configured such that the gamma dose equivalent rate measurement module reciprocates at least in the width direction of the mineral product conveying line, so that the gamma dose equivalent rate measurement module can perform gamma dose equivalent rate measurement at any position in the width direction of the mineral product conveying line, and can also reciprocate in the vertical direction, so that gamma dose equivalent rate measurement can be performed at a set distance above the mineral product.

8. The online radioactivity monitoring system for mineral products according to any one of claims 1 to 2, characterized in that, Also includes: The gamma nuclide identification module analyzes the energy characteristics of radionuclides in mineral products when the radioactivity level exceeds the standard, and provides information on the radionuclides in the mineral products.

9. The online radioactivity monitoring system for mineral products according to any one of claims 1 to 2, characterized in that, Also includes: A mineral product height limiting device is equipped with a height limiting and leveling rod, which is arranged along the running direction of the mineral product conveyor line, located upstream of the radioactivity detection module and above the mineral product conveyor line, and performs height leveling on mineral products that exceed the height limiting and leveling rod.

Images