Method and device for determining the grade of wolframite powder based on specific waveband visible light

Abstract

The application relates to the technical field of ore analysis, and provides a wolframite powder grade determination method and device based on specific waveband visible light, which comprises the following steps: collecting a diffuse reflection signal of a to-be-detected wolframite powder sample in a specific visible light waveband under irradiation of visible light at a preset incident angle; calibrating the diffuse reflection signal based on a reference signal of a preset diffuse reflectance calibration board and gray values of high and low reflectance calibration boards, calculating actual diffuse reflectance of the to-be-detected wolframite powder sample according to a normalization formula; and determining the grade of the to-be-detected wolframite powder sample according to the actual diffuse reflectance based on a mapping relationship between the diffuse reflectance and the grade which is established in advance. The application can realize rapid quantitative determination with a time consumption of no more than 2 minutes and an absolute error of no more than 0.70% in a single detection, does not need chemical reagents, does not depend on a radioactive source, and is suitable for rapid determination of the grade of wolframite powder in an industrial site.

Description

Technical Field

[0001] This application relates to the field of ore analysis technology, and in particular to a method and apparatus for determining the grade of wolframite powder based on visible light of a specific wavelength band, which can be applied to new technology service fields such as mineral exploration or geological exploration. Background Technology

[0002] Wolframite ((Fe,Mn)WO4) is an important mineral raw material for tungsten extraction. Accurate determination of the wolframite powder grade (expressed as the mass fraction of WO3) is crucial for controlling production processes, managing costs, and improving resource utilization during mining, beneficiation, and smelting. Currently, methods for detecting wolframite grade mainly fall into two categories: chemical analysis methods, such as titration, cinquercetin gravimetric analysis, and spectrophotometry, are cumbersome, time-consuming, and require large amounts of chemical reagents, easily causing environmental pollution; instrumental analysis methods, such as X-ray fluorescence spectrometry, atomic absorption spectrometry, and inductively coupled plasma atomic emission spectrometry, involve expensive equipment, high maintenance costs, and some equipment is subject to strict restrictions based on radiation source control. Neither of these methods can meet the demands of industrial sites for rapid, low-cost, and non-destructive testing.

[0003] Light reflection refers to the phenomenon where, when light travels from one medium to the interface between two media, a portion of the light returns to the original medium, changing its direction of propagation. In the field of material composition analysis, different substances exhibit selective absorption and reflection characteristics for incident light of different wavelengths due to differences in their atomic structure, chemical bond energy, and surface morphology. The reflectance characteristics of minerals to visible light are closely related to their chemical composition and crystal structure. Wolframite ((Fe,Mn)WO4) is black or dark brown, exhibiting strong absorption and weak reflection of visible light, with a diffuse reflectance typically below 20%. In contrast, common gangue minerals such as quartz and calcite show strong reflection of visible light, with diffuse reflectance typically above 40%. Furthermore, the color of wolframite exhibits a regular variation with changes in its internal Fe / Mn ratio and WO3 content: the higher the grade, the more dark components the mineral contains, the stronger its absorption of visible light, and the lower its diffuse reflectance. Therefore, there is a definite negative correlation between the grade of wolframite and its diffuse reflectance, providing a physical basis for quantitative grade determination using optical reflectance information.

[0004] However, within the entire visible light spectrum, the diffuse reflectance curves of different minerals overlap, making it difficult to establish a stable, single-valued correspondence between grade and diffuse reflectance based solely on the overall diffuse reflectance. Therefore, this application proposes a method for rapid qualitative identification and quantitative determination of minerals using diffuse reflectance information from specific visible light bands, based on the fact that different minerals exhibit varying diffuse reflectance in specific bands, resulting in characteristic reflectance spectra. Summary of the Invention

[0005] The purpose of this application is to provide a method and apparatus for determining the grade of wolframite powder based on visible light in a specific wavelength band, in order to solve the following technical problems existing in the prior art: Existing chemical analysis methods (titration, cinquerin gravimetric method, spectrophotometry, etc.) are cumbersome and time-consuming, and require a large amount of chemical reagents, which can easily cause environmental pollution; Existing instrumental analysis methods (X-ray fluorescence spectrometry, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, etc.) are expensive and have high maintenance costs, and some equipment is also subject to strict restrictions on radiation source control; At the same time, in the entire visible light wavelength range, the diffuse reflectance curves of different minerals overlap, and it is difficult to establish a stable single-value correspondence between grade and diffuse reflectance based solely on the overall diffuse reflectance, which makes it difficult to achieve rapid quantitative detection based on optical reflectance.

[0006] To achieve the above objectives, this application adopts the following technical solution: A method for determining the grade of wolframite powder based on visible light in a specific wavelength band includes the following steps: Step 1: Using a specific visible light band that prevents the diffuse reflectance of wolframite and gangue minerals from overlapping as the detection band, a detection head equipped with a filter that only allows the specific visible light band to pass through is used to collect diffuse reflectance signals from the surface of the sample to be tested. Step 2: Place the high-reflectivity calibration plate and the low-reflectivity calibration plate on the testing platform respectively, and measure the gray values ​​of the high-reflectivity calibration plate and the low-reflectivity calibration plate respectively. Calculate the diffuse reflectance of the sample using the following formula: ;

[0007] In the formula, Dr 样 The diffuse reflectance of the sample is %; L 样 The gray value of the sample is dimensionless; L 高 The grayscale value of the high reflectivity calibration plate is dimensionless; L 低 Grayscale values ​​for low reflectivity calibration plates, dimensionless; Dr 高 The diffuse reflectance of the high reflectance calibration plate is %; Step 3: Based on the actual mineral composition of the target mine, prepare multiple sets of calibration samples by artificially blending pure minerals in proportion. Determine the WO3 grade of each set of calibration samples by chemical method. Measure the diffuse reflectance of each set of calibration samples according to the method in Step 2 and establish a calibration curve of diffuse reflectance (x) - grade (y). Step 4: Prepare the wolframite powder to be tested into a flat disc-shaped sample. Collect diffuse reflection signals at multiple points within the effective detection area of ​​the disc-shaped sample, calculate the average diffuse reflectance, and substitute the average diffuse reflectance into the calibration curve to calculate the grade of the wolframite powder to be tested.

[0008] In the above scheme, by selecting specific wavelengths where the diffuse reflectance of wolframite and gangue minerals do not overlap for detection, the interference of gangue mineral reflection signals can be eliminated, and a stable single-value correspondence between diffuse reflectance and grade can be established. By using a dual-end calibration plate with high and low reflectance to normalize the background gray value of the detection system, the influence of ambient light changes and system background can be eliminated, ensuring the accuracy of diffuse reflectance calculation. By collecting data from multiple points within the effective detection area of ​​the sample and averaging the values, the interference of sample surface pressing and uneven distribution on the measurement results can be eliminated.

[0009] Furthermore, the specific visible light band is 470-480nm. Full-band scanning experiments have confirmed that within the 470-480nm range, the diffuse reflectance values ​​of minerals such as wolframite, scheelite, chalcopyrite, biotite, quartz, calcite, and muscovite do not overlap, effectively distinguishing wolframite from the main gangue minerals. This is the optimal specific band for establishing a single-value correspondence between grade and diffuse reflectance.

[0010] Furthermore, in step 1, two detection light sources are symmetrically arranged around the detection head. The detection light sources illuminate the sample onto the detection platform at an angle of 30-60° with the central axis of the detection head as the baseline. This symmetrical tilting illumination method can form a uniform and stable diffuse reflection light field on the sample surface, effectively suppressing specular reflection components and improving the signal-to-noise ratio of the diffuse reflection signal.

[0011] Specifically, the detection light source is a halogen lamp, and the tilt angle is 45°. The halogen lamp can provide broadband stable visible light covering the 470-480nm wavelength band, and the 45° tilt angle is an optimal angle that balances the intensity and uniformity of diffuse reflection signals.

[0012] Furthermore, the high-reflectivity calibration plate is an aluminum plate coated with optical-grade RefTarget; the low-reflectivity calibration plate is a matte black acrylic plate. The aluminum plate coated with optical-grade RefTarget has stable and uniform diffuse reflectance, reaching over 95%; the matte black acrylic plate has strong light absorption and a diffuse reflectance of no more than 5%. Together, they constitute a reliable dual-endpoint calibration reference. The sufficient separation between the high and low reflectivity endpoints ensures the linear calibration accuracy of the normalized calculation formula for samples with different gray values, minimizing the error in diffuse reflectance calculation.

[0013] Furthermore, in step 3, the purity of the pure mineral is greater than 95%, and the particle size is 0.038-0.074 mm. Using high-purity pure minerals to prepare the calibration sample ensures that the correlation between the grade and diffuse reflectance of the calibration curve is accurate and reliable; controlling the particle size range ensures the consistency of particle size between the calibration sample and the sample to be tested, eliminating the influence of particle size differences on diffuse reflectance.

[0014] Further, in step 4, the thickness of the disc-shaped sample is 2-5 mm, and the diameter is 10 cm. Diffuse reflection signals are collected at multiple points within the effective detection area. Specifically, at least five points are selected at half the radius of the disc-shaped sample to collect diffuse reflection signals. Preparing the sample into a uniform disc shape ensures the flatness and thickness uniformity of the sample surface, making the diffuse reflection signal stable and repeatable. Collecting signals at multiple points within half the radius avoids the signal instability areas at the center and edges of the disc.

[0015] This application also provides a device for determining the grade of wolframite powder based on visible light of a specific wavelength band, comprising: a detection head equipped with a filter that allows only a specific visible light wavelength band to pass through, for receiving diffuse reflection signals, wherein the specific visible light wavelength band ensures that the diffuse reflectance of wolframite and gangue minerals does not overlap; a light source assembly including two detection light sources symmetrically arranged on both sides of the detection head, illuminating the detection platform at an inclined angle; a detection platform located directly below the detection head for carrying the sample to be tested; a calibration assembly including a high reflectance calibration plate and a low reflectance calibration plate; and a data processing system connected to the detection head for acquiring grayscale values, calculating diffuse reflectance, and outputting grade results. The modules work collaboratively. The light source assembly illuminates the sample at an inclined angle to generate a diffuse reflection signal. The diffuse reflection light is filtered by the filter and then acquired by the detection head. The data processing system, based on the dual-endpoint calibration reference provided by the calibration assembly, acquires the grayscale value of the sample to be tested, calculates the diffuse reflectance, and finally outputs the grade result, realizing fully automated detection from light signal acquisition to grade output.

[0016] Furthermore, the detection head is located 40-100cm above the central axis of the detection platform. This distance range ensures that the detection head's field of view covers the entire sample area, while also ensuring that the diffuse reflection signal intensity meets the requirements for grayscale value acquisition. The detection head is equipped with a filter lens that allows wavelengths of 470-480nm to pass through, making the device sensitive only to specific wavelengths where the diffuse reflectance of wolframite and gangue minerals do not overlap, thus ensuring mineral selectivity of the detection signal from a hardware perspective.

[0017] Preferably, the detection light source is a halogen lamp, which is incident on the sample at an angle of 30-60° with the central axis of the detection head as the baseline, and the receiving angle of the detection head is 0°; the specific incident angle and receiving angle range optimize the collection efficiency of diffuse reflection light and reduce specular reflection interference.

[0018] Preferably, the high-reflectivity calibration plate is an aluminum plate coated with optical-grade RefTarget, with dimensions of 50cm × 50cm; the low-reflectivity calibration plate is a matte black acrylic plate, with dimensions of 40cm × 40cm. The calibration plate areas of the above-mentioned dimensions fully cover the acquisition field of view of the detection head, ensuring the accuracy and representativeness of the calibrated grayscale values.

[0019] Compared with the prior art, this application has the following beneficial effects: 1. By selecting a specific visible light band of 470-480nm as the detection band, the diffuse reflectance of wolframite and other major gangue minerals such as quartz, calcite, muscovite, and scheelite do not overlap in this band. This effectively solves the technical problem that the cross-over of diffuse reflectance curves across the entire band makes it impossible to establish a single-value correspondence between grade and diffuse reflectance. This provides a reliable technical path for the rapid quantitative determination of wolframite powder grade based on the principle of optical diffuse reflectance. 2. By using a high reflectivity calibration plate (diffuse reflectivity not less than 95%) and a low reflectivity calibration plate (diffuse reflectivity not more than 5%) for dual-endpoint background gray value normalization calibration, combined with a sampling method of averaging multiple points at half the radius of the sample, the interference of ambient light fluctuations, system background and sample surface inhomogeneity on the measurement results is eliminated, so that the absolute measurement error does not exceed 0.70%, and the detection accuracy reaches the level comparable to chemical methods; 3. This application adopts the visible light diffuse reflection optical detection principle, which does not require chemical reagents, does not rely on radiation sources, is non-destructive to samples, takes no more than 2 minutes for a single detection, has low detection cost, and does not cause environmental pollution. It overcomes the shortcomings of existing chemical analysis methods, such as long time consumption, large reagent consumption, expensive equipment, and radiation source control of instrumental analysis methods. It is suitable for rapid quantitative determination of the grade of wolframite powder in industrial settings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the wolframite powder grade measuring device.

[0021] Figure 2 The diffuse reflectance curves of pure minerals such as wolframite, scheelite, chalcopyrite, biotite, quartz, calcite, and muscovite in the 400-780nm wavelength range are shown.

[0022] Figure 3 This is a schematic diagram of the sampling location at half the radius of the disc-shaped sample to be tested.

[0023] Figure 4 A calibration curve for diffuse reflectance (x) versus WO3 grade (y).

[0024] The figures are labeled as follows: 1. Detection head; 2. Detection light source; 3. Detection platform; 4. Calibration whiteboard; 5. Calibration blackboard; 6. Identification and monitoring software system; 7. Detection fixing stand; 8. Sample; 9. Filter lens. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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, 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.

[0026] This application relates to a method and apparatus for determining the grade of wolframite powder based on a specific wavelength of visible light, aiming to solve the problems of long processing time and high reagent consumption in existing chemical analysis methods, and the high cost and radioactive source control of instrumental analysis methods. The core technical mechanism lies in: selecting a specific wavelength of visible light where the diffuse reflectance of wolframite and gangue minerals do not overlap, and establishing a quantitative calibration relationship between diffuse reflectance and WO3 grade through background correction with a dual-endpoint calibration plate and multi-point averaging sampling, thereby achieving rapid optical quantitative determination.

[0027] Reference Figure 1 In one embodiment, the wolframite powder grade measuring device includes three parts: an optical detection module, a calibration module, and a support and software module.

[0028] The optical inspection module includes an inspection head 1, an inspection light source 2, and an inspection platform 3. The inspection head 1 is located above the central axis of the inspection platform 3 and is equipped with a filter lens 9 inside. This filter lens 9 only allows specific visible light bands to pass through, thereby making the inspection head 1 sensitive only to specific bands where the diffuse reflectance of wolframite and gangue minerals do not overlap.

[0029] The detection light source 2 includes two halogen lamps, which are symmetrically arranged on both sides of the detection head 1. The two halogen lamps form a triangle with the central axis of the detection head 1 as the baseline and the detection platform 3 as the vertex, with an included angle of 30-60°, preferably 45°.

[0030] The detection platform 3 is located 40-100cm directly below the detection head 1 and is used to support the sample 8 to be tested.

[0031] The calibration module includes a high-reflectivity calibration board and a low-reflectivity calibration board. Specifically, the high-reflectivity calibration board is the calibration white board 4, and the low-reflectivity calibration board is the calibration black board 5. The calibration white board 4 is an aluminum plate with an optical-grade reflective coating and high-precision optical markers (RefTarget), measuring 50cm x 50cm, with a diffuse reflectance of no less than 95%. The calibration black board 5 is a matte black acrylic board, measuring 40cm x 40cm, with a diffuse reflectance of no more than 5%.

[0032] The support and software modules include an identification and monitoring software system 6 and a detection mounting stand 7. The identification and monitoring software system 6 is connected to the detection head 1 and is used to collect grayscale values, calculate diffuse reflectance, and output grade results. It can automatically complete the entire process from light signal acquisition to grade output. The detection mounting stand 7 serves as the assembly frame for the above-mentioned devices and is detachably connected to each component.

[0033] In the above device, the detection light source 2 illuminates the detection platform 3 at an angle of 30-60°. After the light reaches the surface of the sample 8, it undergoes diffuse reflection. The diffusely reflected light passes through the filter lens 9 and reaches the detection head 1. The identification and monitoring software system 6 collects the sample gray value and calculates the diffuse reflectance, and finally outputs the grade result.

[0034] The principle for calculating diffuse reflectance is as follows: By collecting the grayscale values ​​of the sample and measuring the grayscale values ​​of the calibrated white board 4 and calibrated black board 5, the diffuse reflectance is calculated using the following formula: ;

[0035] In the formula, Dr 样 L represents the diffuse reflectance of the sample. 样 L represents the grayscale value of the sample. 高 For the grayscale value of the high reflectivity calibration plate; L 低 Gray values ​​for low reflectivity calibration plates; Dr 高 The diffuse reflectance of the high reflectance calibration plate.

[0036] In a specific embodiment of the present invention, the measured L 高 =242, L 低 =2, calibrating the diffuse reflectance R of the whiteboard 白 =95%, substituting into the above formula yields a simplified calculation formula: ; It should be noted that L 高 =242、L 低 =2 is only the measured value of the high and low reflectivity calibration plates in this embodiment. In actual applications, it can be recalculated based on the on-site calibration results. The sufficient separation between the high and low reflectivity calibration endpoints ensures the linear calibration accuracy of the normalized calculation formula for samples with different gray values, minimizing the error in diffuse reflectivity calculation.

[0037] Combination Figure 2 In one implementation, the process for determining a specific detection band is as follows: The diffuse reflectance of seven pure minerals—wolfonite, scheelite, chalcopyrite, biotite, quartz, calcite, and muscovite—was measured using a full-band visible light scan in the wavelength range of 400-780 nm. Diffuse reflectance-wavelength curves were plotted for each mineral.

[0038] The scanning results show that in the short-wavelength region of 400-470nm, the diffuse reflectance curves of calcite, quartz, and muscovite show a steep upward trend, and the spectral differences are significantly affected by surface roughness. In the long-wavelength region of 550-780nm, the diffuse reflectance curves of biotite and chalcopyrite intersect multiple times, and the reflectance of some minerals drifts significantly with increasing wavelength, indicating insufficient stability. After comprehensive comparison, the 470-480nm band meets the following three conditions: (1) the diffuse reflectance values ​​of wolframite and all major gangue minerals are significantly separated; (2) the reflectance of each mineral in this band changes little with wavelength and is not sensitive to wavelength drift of the light source; (3) this band is located in the central region of visible light, with high intensity of halogen lamp light source, high quantum efficiency of silicon-based detector, and low hardware implementation cost. Based on this, 470-480nm is determined to be the optimal feature detection band of this invention.

[0039] Furthermore, the filter lens 9 is designed to allow only the 470-480nm wavelength band to pass through. The diffuse reflection signal collected by the detection head 1 comes only from this specific wavelength band, which enables the interference of other band gangue mineral reflection signals to be eliminated at the hardware level, ensuring the single-valuedness and stability of the grade-diffuse reflectance correspondence.

[0040] In one embodiment, the method for determining the grade of wolframite powder is performed according to the following steps: Step one is equipment debugging. Adjust the detection head 1 and the detection platform 3 to a predetermined distance, preferably 50cm; adjust the detection light source 2 to a predetermined angle, preferably 45°; turn on the power, preheat the optical detection module for 30 minutes, and proceed with subsequent operations after the light source and sensor reach a thermally stable state.

[0041] Step two is background grayscale value calibration. Place the calibration whiteboard 4 on the detection platform 3, open the recognition and monitoring software system 6, and measure the grayscale value of the calibration whiteboard 4, denoted as L. 高 ; Perform the same operation, replacing the calibration whiteboard 4 with the calibration blackboard 5, and measure the grayscale value of the calibration blackboard 5, denoted as L. 低 Complete the two-endpoint calibration.

[0042] Step three involves determining the effective visible light band. A full-band scan of 400-780nm is used to test the diffuse reflectance of the main minerals in the target mine, identifying specific bands where the diffuse reflectance of each mineral does not overlap. In one embodiment, this specific band is 470-480nm, corresponding to the transmission band of filter 9.

[0043] Step four involves creating a diffuse reflectance-grade calibration curve, including: (1) Preparation of calibration samples: Based on the actual mineral composition of the target mine, multiple sets of calibration samples were prepared by artificial blending of pure minerals in a certain proportion. The WO3 grade of each set of calibration samples was determined by chemical method, and the diffuse reflectance of each set of calibration samples was measured to establish a calibration curve of diffuse reflectance (x, %) - grade (y, %). Among them, the purity of pure minerals should be greater than 95%, and the particle size should be 0.038-0.074 mm.

[0044] (2) Diffuse reflectance measurement: First, press each group of calibration samples into a round disc shape using the same pressure, ensuring a flat surface. The disc shape should be 10 cm in diameter and 2-5 mm thick. Place the disc-shaped sample on the detection platform 3. Then, perform the measurement, combined with... Figure 3 Diffuse reflection signals were collected at different points along half the radius of the disc-shaped sample. At least five points were selected, and the gray values ​​of the samples were measured by the identification and monitoring software system 6 and converted into diffuse reflectance. The average value was taken as the diffuse reflectance of the sample.

[0045] (3) Calibration curve fitting: combined with Figure 4 The diffuse reflectance (x)-WO3 grade (y) calibration curves of each group of calibrated samples were plotted, and linear regression fitting was performed to obtain the calibration equation. The correlation coefficient R² was required to be in the range of 0.98-1.00 to indicate that there is a high linear correlation between diffuse reflectance and WO3 grade.

[0046] Step five is the determination of the grade of the wolframite powder to be tested. The sample to be tested is prepared into a disc-shaped sample using the same method as in step four, and placed on the detection platform 3. The diffuse reflectance signal is collected at different points at half the radius of the disc-shaped sample, the gray value is measured and converted into diffuse reflectance, and the measurement is repeated at no less than 5 points. The average diffuse reflectance is calculated, and the average diffuse reflectance is substituted into the calibration curve equation to calculate the grade of the wolframite powder to be tested. Example 1

[0047] This embodiment uses unknown grade wolframite powder from a tungsten mine in Jiangxi Province, and the grade determination method described above is followed.

[0048] Step 1: Adjust the distance between the detection head 1 and the detection platform 3 to 50cm, adjust the detection light source 2 to a 45° angle, turn on the power, and preheat for 30 minutes.

[0049] Step 2: Place the calibration white board 4 on the detection platform 3 and measure the grayscale value L. 高 =242; Replace with calibration blackboard 5, and measure the grayscale value L. 低 =2.

[0050] Step 3: Use a full-band scan of 400-780nm to determine 470-480nm as the effective specific detection band.

[0051] Step 4: Use pure minerals (wolfonite, scheelite, chalcopyrite, biotite, quartz, calcite, and muscovite) with a purity greater than 95% and a particle size of 0.038-0.074mm for blending. The artificial blending ratio is determined based on the actual mineral composition statistics from a tungsten mine in Jiangxi Province. Artificial blending and mixing are performed according to the following mass fraction ratios: wolfonite 1.92%-28.86%, scheelite 2.89%-4.81%, chalcopyrite 0.10%-0.29%, biotite 4.81%-11.54%, quartz 48.10%-62.53%, calcite 0.48%-4.81%, and muscovite 9.62%-19.24%. The mass fraction ratio of each pure mineral can be varied independently. The total mass of the blended ore is 50g.

[0052] Five sets of calibration samples were prepared according to the above ratio. The grades were determined by chemical method (the gravimetric method was used for WO3 grade ≥10%, and the spectrophotometric method was used for WO3 grade <10%), and the grades were 5.18%, 11.16%, 16.07%, 21.99%, and 25.60%, respectively.

[0053] Each group of calibration samples was prepared into a disc shape with a diameter of 10 cm and a thickness of 5 mm. Diffuse reflectance signals were collected at five points along a half-radius ring. The diffuse reflectance of the sample with a grade of 5.18% was 59.1%, 58.8%, 58.5%, 59.5%, and 59.2% in five measurements, with an average of 59.0%. The average diffuse reflectance of the calibration samples with grades of 11.16%, 16.07%, 21.99%, and 25.60% were 53.5%, 47.5%, 43.0%, and 39.6%, respectively.

[0054] Based on the above test data, a calibration curve of diffuse reflectance (x, %) - grade (y, %) was plotted, and the linear regression equation obtained by fitting the curve was: y=-1.04297x+66.60469, R²=0.99377 Formula 3; Step 5: Prepare the wolframite powder to be tested into a disc shape with a diameter of 10 cm and a thickness of 5 mm. Collect diffuse reflectance signals at 5 points along a ½ radius ring and calculate the average diffuse reflectance as 55.8%. Substitute 55.8 into Formula 3: y = -1.04297x + 66.60469, and calculate the WO3 grade as 8.41%.

[0055] The same sample was calibrated using a spectrophotometric method, and the result was 8.18%. The absolute error between the result obtained in this embodiment and the value calibrated by the chemical method is 0.23%. Example 2

[0056] Except for the sample to be tested in step five, the other steps in this embodiment are exactly the same as in embodiment 1, and the calibration curve equation is still y=-1.04297x+66.60469.

[0057] The average diffuse reflectance of the sample was determined to be 48.7% using the above method. Substituting this into the calibration curve equation, the WO3 grade was calculated to be 15.81%. Subsequently, the WO3 grade of the sample was calibrated to be 15.11% using the cinquerin gravimetric method. The absolute error between the two was 0.70%. Example 3

[0058] Except for the sample to be tested in step five, the other steps in this embodiment are exactly the same as in embodiment 1, and the calibration curve equation is still y=-1.04297x+66.60469.

[0059] The average diffuse reflectance of the sample was determined to be 46.3% using the above method. Substituting this into the calibration curve equation, the WO3 grade was calculated to be 18.32%. Subsequently, the WO3 grade of the sample was calibrated to be 18.17% using the cinquerin gravimetric method. The absolute error between the two was 0.15%.

[0060] The measurement results of the above three embodiments show that the absolute error between the WO3 grade measured by the method of this application and the chemical calibration value does not exceed 0.70%, confirming that the method of this application has high accuracy and repeatability. Provided that equipment preheating and calibration curve preparation are completed, the time for a single sample from placement on the detection platform to outputting the grade result is no more than 2 minutes. It requires no chemical reagents, does not rely on a radiation source, is non-destructive to the sample, and is suitable for rapid quantitative determination of wolframite powder grade in industrial settings.

[0061] It is understandable that the coefficients of the above calibration curve equation (y=-1.04297x+66.60469) are the measured calibration results under specific mineral composition conditions at a tungsten mine industrial site in Jiangxi Province. The calibration curve is applicable to wolframite powder with a grade of 5.18%-25.60%. If the grade exceeds this range, a new calibration curve should be prepared. If used in other mining industrial sites, calibration samples should be prepared again according to the actual mineral composition at the site, and a calibration curve suitable for that site should be prepared.

[0062] It is understood that the filtering device is not limited to a filter lens, but can also be other optical filtering elements that only allow specific visible light bands to pass through, as long as they enable the detection head to be sensitive only to specific bands where the diffuse reflectance of wolframite and gangue minerals do not overlap.

[0063] It is understood that the detection light source is not limited to halogen lamps, but can also be other light sources that can provide broadband stable visible light covering the 470-480nm wavelength band, as long as they can cooperate with the detection head to form an effective diffuse reflection signal acquisition.

[0064] Where there is no conflict, the technical features in the foregoing embodiments can be combined with each other.

[0065] The embodiments disclosed in this application are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this application based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this application, they are all within the protection scope of this application.

Claims

1. A method for determining the grade of wolframite powder based on visible light in a specific wavelength band, characterized in that, Includes the following steps: Step 1: Using a specific visible light band that prevents the diffuse reflectance of wolframite and gangue minerals from overlapping as the detection band, a detection head equipped with a filter that only allows the specific visible light band to pass through is used to collect diffuse reflectance signals from the surface of the sample to be tested. Step 2: Place the high-reflectivity calibration plate and the low-reflectivity calibration plate on the testing platform respectively, and measure the gray values ​​of the high-reflectivity calibration plate and the low-reflectivity calibration plate respectively. Calculate the diffuse reflectance of the sample using the following formula: ； In the formula, Dr 样 L represents the diffuse reflectance of the sample. 样 L represents the grayscale value of the sample. 高 For the grayscale value of the high reflectivity calibration plate; L 低 Gray values ​​for low reflectivity calibration plates; Dr 高 The diffuse reflectance of the high reflectance calibration plate; Step 3: Based on the actual mineral composition of the target mine, prepare multiple sets of calibration samples by artificially blending pure minerals in proportion. Use chemical methods to calibrate the WO3 grade of each set of calibration samples, measure the diffuse reflectance of each set of calibration samples, and establish a diffuse reflectance (x) - grade (y) calibration curve. Step 4: Prepare the wolframite powder to be tested into a flat disc-shaped sample. Collect diffuse reflection signals at multiple points within the effective detection area of ​​the disc-shaped sample, calculate the average diffuse reflectance, and substitute the average diffuse reflectance into the calibration curve to calculate the grade of the wolframite powder to be tested.

2. The method for determining the grade of wolframite powder according to claim 1, characterized in that, The specific visible light wavelength range is 470-480nm.

3. The method for determining the grade of wolframite powder according to claim 1, characterized in that, In step 1, two detection light sources are symmetrically arranged around the detection head. The detection light sources illuminate the sample onto the detection platform at an angle of 30-60° with the central axis of the detection head as the baseline.

4. The method for determining the grade of wolframite powder according to claim 1, characterized in that, The high reflectivity calibration plate is an aluminum plate coated with optical-grade RefTarget; the low reflectivity calibration plate is a matte black acrylic plate.

5. The method for determining the grade of wolframite powder according to claim 4, characterized in that, The diffuse reflectance of the high reflectance calibration plate is not less than 95%, and the diffuse reflectance of the low reflectance calibration plate is not more than 5%.

6. The method for determining the grade of wolframite powder according to claim 1, characterized in that, In step 3, the purity of the pure mineral is greater than 95% and the particle size is 0.038-0.074 mm.

7. The method for determining the grade of wolframite powder according to claim 1, characterized in that, In step 4, the thickness of the disc-shaped sample is 2-5 mm and the diameter is 10 cm. The process of collecting diffuse reflection signals at multiple points within the effective detection area is to select no less than 5 points at half the radius of the disc-shaped sample to collect diffuse reflection signals.

8. A device for determining the grade of wolframite powder based on visible light of a specific wavelength band, used to perform the method as described in claims 1-7, characterized in that, include: The detection head is equipped with a filter that allows only a specific visible light band to pass through, for receiving diffuse reflection signals. The specific visible light band ensures that the diffuse reflectance of wolframite and gangue minerals does not overlap. The light source assembly includes two detection light sources, symmetrically arranged on both sides of the detection head, which illuminate the detection platform at an inclined angle. The testing platform, located directly below the testing head, is used to hold the sample to be tested; The calibration components include a high-reflectivity calibration plate and a low-reflectivity calibration plate; The data processing system, connected to the detection head, is used to collect grayscale values, calculate diffuse reflectance, and output grade results.

9. The apparatus for determining the grade of wolframite powder according to claim 8, characterized in that, The detection head is located 40-100cm above the central axis of the detection platform, and the inside of the detection head is equipped with a filter lens that allows wavelengths of 470-480nm to pass through; The detection light source is a halogen lamp, which is incident on the sample at an angle of 30-60° with the central axis of the detection head as the baseline, and the receiving angle of the detection head is 0°. The high reflectivity calibration plate is an aluminum plate coated with optical-grade RefTarget, with dimensions of 50cm×50cm; the low reflectivity calibration plate is a matte frosted black acrylic plate, with dimensions of 40cm×40cm.

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