Coal density distribution and particle size distribution measuring system and method

Abstract

The invention discloses a coal density distribution and particle size distribution measuring system and method, and relates to the field of coal washing, and the system comprises a coal sample conveying device, an X-ray source, an X-ray detector, a rotating rack, an angle sensor and a computer; the X-ray source and the X-ray detector are symmetrically fixed on the rotating rack, and the rotating rack is used for driving the X-ray source and the X-ray detector to rotate; the angle sensor is arranged on the rotating rack; the coal sample conveying device conveys a to-be-detected coal sample into an imaging area of the X-ray source, the X-ray source emits X-rays to penetrate through the to-be-detected coal sample in the rotating process, the X-ray detector collects X-ray projection images at multiple angles, and the angle sensor collects the rotating angle of the rotating rack in the rotating process; and the computer generates a coal sample cross section image through a CT reconstruction algorithm according to the X-ray projection image and the rotation angle, and calculates the density distribution and the particle size distribution of the coal sample. According to the invention, the accuracy and speed of density distribution and particle size distribution measurement can be improved.

Description

Technical Field

[0001] This application relates to the field of coal washing and beneficiation, and in particular to a coal density distribution and particle size distribution measurement system and method. Background Technology

[0002] Coal mined from coal mines is crushed and screened to become "raw coal". The raw coal needs to be sent to washing and beneficiation equipment to separate coal from gangue. The determination of washing and beneficiation parameters and the optimization of yield depend on the density distribution (mass percentage of ore of various densities in the total) and particle size distribution (mass percentage of ore of various particle sizes in the total) of the raw coal. Therefore, the measurement of these two parameters is crucial to the washing and beneficiation process.

[0003] Traditional density distribution measurement employs a "buoyancy-sinking experiment," which utilizes the difference in buoyancy and sinking of coal particles of different densities in heavy liquids (such as zinc chloride solution). Coal samples are placed in heavy liquids of different densities to separate products of different density grades, allowing for analysis of density composition. This is a core method for assessing coal washability and determining separation density. However, the process is complex, requiring steps such as coal sample preparation (screening and weighing), equipment and reagent preparation (preparation of heavy liquid), coal sample pretreatment (cleaning coal slime and recovery), stratified separation (immersion in buffer solution and controlled-time removal of floating matter), layer-by-layer separation (transferring sediment to the next level of heavy liquid), coal sample cleaning, drying, weighing, and data calculation and verification. This process takes 40 minutes to 2.5 hours, resulting in a large workload and long time lag, making it unsuitable for quickly guiding coal washing and processing.

[0004] Although some companies have developed automatic floating and sinking test devices that replace manual labor with electronic control to save manpower, they still need to complete all the steps of traditional experiments. The time lag has not been significantly improved, and the system's mechanical actuators are complex with many control links, making it prone to failure. Summary of the Invention

[0005] The purpose of this application is to provide a coal density distribution and particle size distribution measurement system and method, which can improve the accuracy and speed of density distribution and particle size distribution measurement.

[0006] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a coal density distribution and particle size distribution measurement system, comprising: a coal sample conveying device, an X-ray source, an X-ray detector, a rotating frame, an angle sensor, and a computer; the X-ray source and the X-ray detector are symmetrically fixed on the rotating frame, and the rotating frame is used to drive the X-ray source and the X-ray detector to rotate; the angle sensor is disposed on the rotating frame; The coal sample conveying device delivers the coal sample to be tested into the imaging area of ​​the X-ray source. The X-ray source emits X-rays that penetrate the coal sample during rotation. The X-ray detector acquires X-ray projection images at multiple angles, and the angle sensor acquires the rotation angle during the rotation of the rotating frame. The computer is connected to the X-ray detector and the angle sensor respectively, and is used to generate a cross-sectional image of the coal sample using a CT reconstruction algorithm based on the X-ray projection image and the rotation angle, and to calculate the density distribution and particle size distribution of the coal sample based on the cross-sectional image of the coal sample.

[0007] Secondly, this application provides a method for measuring the density distribution and particle size distribution of coal, wherein the method is applied to the aforementioned coal density distribution and particle size distribution measurement system, and the method includes: Place the coal sample to be tested in the imaging area of ​​the X-ray source; The X-ray source and X-ray detector are controlled to rotate synchronously around the coal sample to be tested, and X-ray projection images at multiple angles are acquired and the corresponding rotation angles are recorded synchronously. Based on the X-ray projection image and rotation angle, a cross-sectional image of the coal sample is generated using a CT reconstruction algorithm; The density is calculated based on the grayscale value of each pixel in the cross-sectional image of the coal sample, and a density image is generated. The density image was segmented into particles using an image recognition algorithm to identify multiple material blocks; Calculate the density and particle size parameters of each material block; The density and particle size parameters of all material blocks were statistically analyzed to obtain the density distribution and particle size distribution of the coal sample to be tested.

[0008] Thirdly, this application provides a method for measuring the density distribution and particle size distribution of coal, the method being applied to the aforementioned coal density distribution and particle size distribution measurement system, the method comprising: Place the coal sample to be tested in the imaging area of ​​the X-ray source; The X-ray source and X-ray detector are controlled to rotate synchronously around the coal sample to be tested, and X-ray projection images at multiple angles are acquired and the corresponding rotation angles are recorded synchronously. Based on the X-ray projection image and rotation angle, a cross-sectional image of the coal sample is generated using a CT reconstruction algorithm; Image recognition algorithms are used to distinguish between material regions and void regions in the cross-sectional image of the coal sample; The density is calculated based on the gray values ​​of the pixels in the material region to obtain the density distribution of the coal sample to be tested and generate a density image. The density image was segmented into particles using an image recognition algorithm to identify multiple material blocks; Calculate the particle size parameters of each material block and perform statistical analysis to obtain the particle size distribution of the coal sample to be tested.

[0009] According to the specific embodiments provided in this application, this application has the following technical effects: (1) Significantly improves measurement speed: By rotating the X-ray source and X-ray detector and combining it with the CT reconstruction algorithm, the density and particle size distribution of a single coal sample can be measured quickly, which is more efficient and accurate than the traditional floating and sinking experiment; (2) No chemical reagents or human intervention required: This application eliminates the heavy liquid flotation process, avoids the use of toxic and harmful reagents such as zinc chloride, reduces environmental and health risks, and at the same time reduces human dependence and improves operational safety and automation level; (3) Reliable structure and low failure rate: Compared with the complex liquid circuit and mechanical action of the automatic floating and sinking device, this application is based on solid-state imaging and software analysis, with fewer mechanical moving parts (only the rotating frame and coal sample conveying device), and the system has high stability and low maintenance cost. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A schematic diagram of a coal density and particle size distribution measurement system provided in an embodiment of this application when the rotating frame is a turntable bearing structure; Figure 2 A schematic diagram of the structure of a coal density and particle size distribution measurement system provided in an embodiment of this application when the rotating frame is a C-shaped frame; Figure 3 This is a schematic diagram of the structure of a coal density and particle size distribution measurement system provided in an embodiment of this application when the rotating frame is a C-shaped frame. Detailed Implementation

[0012] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0013] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0014] In one exemplary embodiment, such as Figures 1-3 As shown, a coal density distribution and particle size distribution measurement system is provided, including: a coal sample conveying device 1, an X-ray source 2, an X-ray detector 3, a rotating frame, an angle sensor (not shown in the figure), and a computer (not shown in the figure). The X-ray source 2 and the X-ray detector 3 are symmetrically fixed on the rotating frame, and the rotating frame is used to drive the X-ray source 2 and the X-ray detector 3 to rotate; the angle sensor is disposed on the rotating frame.

[0015] The coal sample conveying device 1 delivers the coal sample 4 to be tested into the imaging area of ​​the X-ray source 2. The X-ray source 2 emits X-rays that penetrate the coal sample 4 during rotation. The X-ray detector 3 collects X-ray projection images at multiple angles. The angle sensor collects the rotation angle during the rotation of the rotating frame.

[0016] The computer is connected to the X-ray detector 3 and the angle sensor respectively, and is used to generate a cross-sectional image of the coal sample using a CT reconstruction algorithm based on the X-ray projection image and the rotation angle, and to calculate the density distribution and particle size distribution of the coal sample based on the cross-sectional image of the coal sample.

[0017] In one exemplary embodiment, such as Figure 1 As shown, the coal sample conveying device 1 is a belt conveyor, which conveys the coal sample 4 to be tested into the imaging area of ​​the X-ray source 2.

[0018] In another exemplary embodiment, such as Figures 2-3 As shown, the coal sample conveying device 1 includes a sample box 16 and a telescopic rod 15. The sample box 16 is connected to the extendable end of the telescopic rod 15. After the sample box 16 is loaded with the coal sample 4 to be tested, it is sent into the imaging area of ​​the X-ray source 2 by the telescopic rod 15. After the measurement is completed, the telescopic rod 15 retracts the sample box 16. The telescopic rod 15 is driven by a drive device 17 to achieve its telescopic function.

[0019] In one exemplary embodiment, such as Figure 1 As shown, the rotating frame is a turntable bearing structure, which includes an inner ring 5 and an outer ring 6. The X-ray source 2 and the X-ray detector 3 are symmetrically fixed on the inner ring 5 or the outer ring 6. The turntable bearing structure is driven to rotate by a drive motor 7. The turntable bearing structure is supported by a base 8.

[0020] In another exemplary embodiment, such as Figure 2 and Figure 3 As shown, the rotating frame is a C-shaped frame 20 or a C-shaped frame 18. For example... Figure 3 As shown, the X-ray source 2 and the X-ray detector 3 are symmetrically fixed at both ends of the C-shaped frame 20, or, as... Figure 2 As shown, the X-ray source 2 and X-ray detector 3 are symmetrically fixed on the ring 19 of the C-shaped frame 18. The rotating frame, either the C-shaped frame 20 or the C-shaped frame 18, is supported by the bracket 21.

[0021] In one exemplary embodiment, such as Figures 1-3 As shown, the above measurement system also includes a sampler 9, a screening machine 10, and multiple buffer chambers 11; the sampler 9 collects coal samples 4 to be tested from the main coal conveyor belt, the screening machine 10 screens the coal samples 4 to be tested into different particle sizes, and the coal samples 4 of different particle sizes are temporarily stored in the corresponding buffer chambers 11.

[0022] In one exemplary embodiment, such as Figures 1-3 As shown, the above-mentioned measurement system also includes a waste recycling device 12 and a waste return device 14; the waste recycling device 12 receives the measured coal sample and returns the measured coal sample to the waste return device 14 via a screw conveyor 13. The waste return device 14 lifts the coal sample and finally drops it onto the main coal conveyor belt.

[0023] When the coal sample conveying device 1 is a belt conveyor, the measured coal sample is poured into the waste recycling device 12 by the movement of the belt.

[0024] When the coal sample conveying device 1 includes a sample box 16 and a telescopic rod 15, after the measurement is completed, the telescopic rod 15 moves the sample box 16 to the waste recycling device 12. The telescopic rod 15 rotates 180 degrees to pour the measured coal sample into the waste recycling device 12, and then rotates back to its original state. The rotation of the telescopic rod 15 is also achieved by driving it through the drive device 17.

[0025] In one exemplary embodiment, the X-ray detector 3 is a flat panel detector or a multi-layer arc-shaped linear array detector.

[0026] This application effectively overcomes the shortcomings of traditional buoyancy and sinking experiments, such as low efficiency, strong lag, and complex operation, and realizes rapid, environmentally friendly, high-precision, and online measurement of coal density and particle size distribution, which has significant technological progress and industrial application value.

[0027] In an exemplary embodiment, based on the above system, a method for measuring coal density distribution and particle size distribution is provided, including the following steps.

[0028] S1: Place the coal sample to be tested in the imaging area of ​​the X-ray source.

[0029] S2: Control the X-ray source and X-ray detector to rotate synchronously around the coal sample to be tested, acquire X-ray projection images at multiple angles, and record the corresponding rotation angles simultaneously.

[0030] S3: Based on the X-ray projection image and rotation angle, generate a cross-sectional image of the coal sample using a CT reconstruction algorithm.

[0031] S4: Calculate the density based on the grayscale value of each pixel in the cross-sectional image of the coal sample, and generate a density image.

[0032] S5: The density image is segmented into particles using an image recognition algorithm to identify multiple material blocks.

[0033] S6: Calculate the density and particle size parameters of each material block.

[0034] S7: Calculate the density and particle size parameters of all material blocks to obtain the density distribution and particle size distribution of the coal sample to be tested.

[0035] In this embodiment, X-ray CT imaging technology is used to scan and measure the coal sample to obtain multiple cross-sectional images of the coal. The grayscale values ​​of these images are correlated with the density at corresponding points; that is, the density can be calculated based on the grayscale values ​​of each pixel in the cross-sectional image of the coal sample, thus obtaining a density image. Then, using traditional image recognition algorithms (such as Canny edge detection) or AI image recognition methods (such as U-Net and watershed algorithms), block identification is performed on each density image to segment out material blocks of different sizes. The density and size (particle size parameter) of each material block are then calculated, and statistical analysis yields the density and particle size distribution of the coal sample.

[0036] In another exemplary embodiment, based on the above system, a method for measuring coal density distribution and particle size distribution is provided, including the following steps.

[0037] S1: Place the coal sample to be tested in the imaging area of ​​the X-ray source.

[0038] S2: Control the X-ray source and X-ray detector to rotate synchronously around the coal sample to be tested, acquire X-ray projection images at multiple angles, and record the corresponding rotation angles simultaneously.

[0039] S3: Based on the X-ray projection image and rotation angle, generate a cross-sectional image of the coal sample using a CT reconstruction algorithm.

[0040] S4: Use an image recognition algorithm to distinguish between the material region and the void region in the cross-sectional image of the coal sample.

[0041] S5: Calculate the density based on the gray values ​​of the pixels in the material region to obtain the density distribution of the coal sample to be tested and generate a density image.

[0042] S6: The density image is segmented into particles using an image recognition algorithm to identify multiple material blocks.

[0043] S7: Calculate the particle size parameters of each material block and perform statistical analysis to obtain the particle size distribution of the coal sample to be tested.

[0044] In this embodiment, an image recognition algorithm (such as the FCN fully convolutional network image recognition algorithm) is used to distinguish between material regions and void regions in the cross-sectional image of the coal sample. Then, the density of the material regions is calculated to obtain the density distribution of the coal sample to be tested. Further image recognition algorithms (such as the U-Net image segmentation algorithm) are used to segment and identify edges in the density image to obtain material blocks in the density image. The size of these material blocks is then calculated, and finally, the particle size distribution of the coal sample to be tested is calculated.

[0045] The difference between the two statistical density distribution methods mentioned above is as follows: the first method involves first identifying the material blocks, analyzing their density, and then statistically analyzing their density distribution. The second method directly performs density distribution statistics. The data provided by the first method offers more accurate guidance for adjusting the coal washing process, while the second method is simpler to implement.

[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A coal density distribution and particle size distribution measurement system, characterized in that, include: The system includes a coal sample conveying device, an X-ray source, an X-ray detector, a rotating frame, an angle sensor, and a computer; the X-ray source and the X-ray detector are symmetrically fixed on the rotating frame, which drives the X-ray source and the X-ray detector to rotate; the angle sensor is mounted on the rotating frame. The coal sample conveying device delivers the coal sample to be tested into the imaging area of ​​the X-ray source. The X-ray source emits X-rays that penetrate the coal sample during rotation. The X-ray detector acquires X-ray projection images at multiple angles, and the angle sensor acquires the rotation angle during the rotation of the rotating frame. The computer is connected to the X-ray detector and the angle sensor respectively, and is used to generate a cross-sectional image of the coal sample using a CT reconstruction algorithm based on the X-ray projection image and the rotation angle, and to calculate the density distribution and particle size distribution of the coal sample based on the cross-sectional image of the coal sample.

2. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, The coal sample conveying device is a belt conveyor.

3. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, The coal sample conveying device includes a sample box and a telescopic rod; the sample box is connected to the telescopic end of the telescopic rod, and after the sample box is loaded with the coal sample to be tested, it is sent into the imaging area of ​​the X-ray source by the telescopic rod. After the measurement is completed, the telescopic rod retracts the sample box.

4. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, The rotating frame is a turntable bearing structure, which includes an inner ring and an outer ring; the X-ray source and the X-ray detector are symmetrically fixed on the inner ring or the outer ring.

5. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, The rotating frame is a C-shaped frame or a C-shaped frame, and the X-ray source and X-ray detector are symmetrically fixed at both ends of the C-shaped frame, or the X-ray source and X-ray detector are symmetrically fixed on the ring of the C-shaped frame.

6. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, It also includes a sampler, a screening machine, and multiple buffer chambers; the sampler collects coal samples to be tested from the main coal conveyor belt, the screening machine screens the coal samples to be tested into different particle sizes, and the coal samples of different particle sizes are temporarily stored in the corresponding buffer chambers.

7. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, It also includes a waste recycling device and a waste return device; the waste recycling device receives the measured coal sample and returns the measured coal sample to the waste return device via a screw conveyor.

8. The coal density distribution and particle size distribution measurement system according to claim 1, characterized in that, The X-ray detector is a flat panel detector or a multi-layer arc-shaped linear array detector.

9. A method for measuring the density distribution and particle size distribution of coal, characterized in that, The method is applied to the coal density distribution and particle size distribution measurement system according to any one of claims 1-8, and the method includes: Place the coal sample to be tested in the imaging area of ​​the X-ray source; The X-ray source and X-ray detector are controlled to rotate synchronously around the coal sample to be tested, and X-ray projection images at multiple angles are acquired and the corresponding rotation angles are recorded synchronously. Based on the X-ray projection image and rotation angle, a cross-sectional image of the coal sample is generated using a CT reconstruction algorithm; The density is calculated based on the grayscale values ​​of each pixel in the cross-sectional image of the coal sample, and a density image is generated. The density image was segmented into particles using an image recognition algorithm to identify multiple material blocks; Calculate the density and particle size parameters of each material block; The density and particle size parameters of all material blocks were statistically analyzed to obtain the density distribution and particle size distribution of the coal sample to be tested.

10. A method for measuring the density distribution and particle size distribution of coal, characterized in that, The method is applied to the coal density distribution and particle size distribution measurement system according to any one of claims 1-8, and the method includes: Place the coal sample to be tested in the imaging area of ​​the X-ray source; The X-ray source and X-ray detector are controlled to rotate synchronously around the coal sample to be tested, and X-ray projection images at multiple angles are acquired and the corresponding rotation angles are recorded synchronously. Based on the X-ray projection image and rotation angle, a cross-sectional image of the coal sample is generated using a CT reconstruction algorithm; Image recognition algorithms are used to distinguish between material regions and void regions in the cross-sectional image of the coal sample; The density is calculated based on the gray values ​​of the pixels in the material region to obtain the density distribution of the coal sample to be tested and generate a density image. The density image was segmented into particles using an image recognition algorithm to identify multiple material blocks; Calculate the particle size parameters of each material block and perform statistical analysis to obtain the particle size distribution of the coal sample to be tested.

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