A method for detecting water-soluble fluoride ions in recycled black powder

Abstract

A method for detecting water-soluble fluoride ions in recycled black powder, which is based on the operation of a fluoride ion detection device. The device includes a housing with a receiving hole at the top and a magnetic stirring module inside; there is a placement groove on one side of the housing, and a colorimetric cuvette is detachably installed in the placement groove. The method includes: mixing the recycled black powder sample with a quantified amount of water in a mixing container to obtain a mixed solution; placing the mixing container in the receiving hole, stirring it through the magnetic stirring module and then allowing it to stand to obtain an extract containing supernatant; removing interfering ions from the supernatant and transferring it to the colorimetric cuvette, reacting with a fluoride ion chromogenic reagent to obtain a chromogenic solution; using a spectrophotometer to perform long-path and short-path measurements on the chromogenic solution: if the concentration value measured in the long-path is less than the preset safety concentration, it is judged to be qualified; if the concentration value measured in the short-path is greater than the preset safety concentration, it is judged to be unqualified; if the preset safety concentration is between the two, it is judged that laboratory testing is required. This method realizes the on-site rapid screening of water-soluble fluoride ions in recycled black powder.

Description

Technical Field

[0001] This invention belongs to the field of recycled material testing technology, specifically relating to a method for detecting water-soluble fluoride ions in recycled black powder. Background Technology

[0002] Recycled black powder, an intermediate product generated during the recycling of positive and negative electrode materials for lithium batteries, contains valuable metal elements such as lithium, cobalt, nickel, and manganese, and has high resource reuse value. However, during the recycling process, fluorine-containing substances in the electrolyte (such as lithium hexafluorophosphate) are easily hydrolyzed to generate hydrogen fluoride, which then transforms into water-soluble fluoride ions remaining in the black powder. The content of water-soluble fluoride ions is one of the key indicators for evaluating the quality and safety of recycled black powder: excessive content not only corrodes production equipment and increases defluorination costs during subsequent hydrometallurgical or material regeneration processes, but may also pose a risk of fluoride pollution to soil and water bodies due to improper environmental release. With the rapid development of the global lithium battery recycling industry and the increasingly stringent environmental requirements for imported recycled materials in various countries, port regulatory authorities, trading parties, and recycling companies all need to test the water-soluble fluoride ion content in recycled black powder.

[0003] Currently, existing methods for detecting water-soluble fluoride ions in recycled black powder mainly rely on conventional laboratory techniques such as ion chromatography and fluoride ion selective electrode methods. In practical applications, these methods require samples to be sent to specialized laboratories, where professional testing personnel operate large, precision instruments to complete the tests. The process from sample submission to result issuance typically takes several hours or even days, resulting in a long testing cycle and poor timeliness. Furthermore, the entire testing process demands a high level of professional skill from the operators, making it difficult for ordinary on-site personnel to complete independently. This leads to situations where laboratory facilities are unavailable, such as at customs clearance points or during trade transactions, where testing personnel cannot perform immediate and rapid on-site screening of recycled black powder. They must send samples for testing and wait for results, severely impacting customs clearance efficiency and trade delivery progress, and potentially even causing trade disputes due to testing delays. Therefore, there is an urgent need to develop a detection method that can rapidly screen for water-soluble fluoride ions in recycled black powder on-site without relying on a laboratory. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present invention provides a method for detecting water-soluble fluoride ions in recycled black powder, based on the operation of a fluoride ion detection device. The detection device includes a housing, a receiving hole at the top of the housing, and a magnetic stirring module connected to the bottom end of the receiving hole inside the housing; a placement groove is provided on one side of the housing, and a cuvette containing a built-in fluoride ion colorimetric reagent is detachably installed in the placement groove; the method includes: The recycled black powder sample was mixed with a measured amount of water in a mixing container to obtain a mixture; Place the mixing container into the accommodation hole, stir the mixed solution by the magnetic stirring module and then let it stand still to obtain an extract containing a water-soluble fluoride ion supernatant liquid; After removing interfering ions from the supernatant liquid by the purification device, transfer it to a cuvette so that it is mixed and reacted with a fluoride ion chromogenic reagent to obtain a chromogenic solution; Use a spectrophotometer to perform long optical path and short optical path measurements on the chromogenic solution. If the concentration value measured by the long optical path is less than the preset safety concentration, determine that the sample is qualified; if the concentration value measured by the short optical path is greater than the preset safety concentration, determine that the sample is unqualified; if the preset safety concentration is between the concentration values measured by the long optical path and the short optical path, determine that it needs to be sent to the laboratory for testing.

[0005] According to the technical solution provided by the present invention, a first temperature adjustment module and a second temperature adjustment module are further provided inside the housing. The first temperature adjustment module is arranged circumferentially around the side wall of the accommodation hole, and the second temperature adjustment module is arranged on one side of the housing close to the placement groove. The second temperature adjustment module adjusts the temperature synchronously with the first temperature adjustment module; The step of stirring the mixed solution by the magnetic stirring module and then letting it stand still includes: Adjust the first temperature adjustment module to keep the stirring temperature at 25°C - 45°C; Control the magnetic stirring module to stir for 20 min - 40 min, and after stirring, let it stand still at the stirring temperature for 2 min - 5 min.

[0006] According to the technical solution provided by the present invention, the purification device includes: A cylinder shell, a filter element is provided at the liquid inlet end of the cylinder shell, the liquid outlet end is connected to a metering pump through a conduit, and a positioning clamp is provided on the conduit; A filter membrane assembly, the filter membrane assembly is arranged inside the cylinder shell and can slide relative to the cylinder shell along the axial direction of the cylinder shell; A mixed resin filtration column, the mixed resin filtration column is arranged inside the cylinder shell and is located between the liquid outlet end and the filter membrane assembly; the mixed resin filtration column cooperates with the filter element to clamp and fix the filter membrane assembly, and the mixed resin filtration column is used to adsorb metal ions in the solution; The step of transferring the supernatant liquid to a cuvette after removing interfering ions by the purification device includes: Fix the conduit to the container mouth of the mixing container through the positioning clamp so that the liquid inlet of the purification device is suspended in the supernatant liquid, and insert the conduit at the rear end of the metering pump into the liquid injection port of the cuvette; Start the metering pump for the first suction filtration, and discard the obtained liquid to activate the mixed resin filtration column and clean the pipeline; Start the metering pump again for the second suction filtration, so that the supernatant liquid flows through the filter element, the filter membrane assembly and the mixed resin filtration column in sequence and is directly introduced into the cuvette.

[0007] According to the technical solution provided by the present invention, the liquid outlet end of the cylinder shell includes an inner shell and an outer shell arranged coaxially, and a conduit receiving space is formed between the inner shell and the outer shell. The end of the inner shell near the filter screen is fixedly connected to the inner wall of the outer shell and closes one end of the receiving space. The outer shell has at least two elastic pressing parts, which are evenly distributed along the circumference of the cylinder shell. A rotating fastener is sleeved on the outside of the cylinder shell. The inner wall of the rotating fastener is threadedly connected to the external thread of the outer wall of the cylinder shell, and the external thread extends to the outer wall of the outer shell and the outer wall of the elastic pressing part.

[0008] According to the technical solution provided by the present invention, before mixing the recycled black powder sample with a certain amount of water in a mixing container, the method further includes: Take a representative sample of recycled black powder, at least 500g, divide it evenly into multiple portions, and mix the sample from each portion. Weigh 5g of the mixed recycled black powder sample into a mixing container and add distilled water to the mixing container.

[0009] According to the technical solution provided by the present invention, the top of the housing is further provided with a top cover, the top of the housing is provided with a first protruding connecting part, the bottom surface of the top cover is provided with a second concave connecting part corresponding to the first connecting part, and the top cover and the housing are detachably connected through the cooperation of the first connecting part and the second connecting part; a weighing module is provided inside the top cover, and a weighing part corresponding to the weighing module and a display module electrically connected to the weighing module are provided on the top surface of the top cover; The quantitative weighing of 5g of recycled black powder sample includes: Remove the top cover from the shell and lay it flat. Place the sample container on the weighing unit and read and weigh the required mass of the recycled black powder sample through the display module.

[0010] According to the technical solution provided by the present invention, the cuvette has at least three through holes communicating with the interior, and each through hole is provided with a detachable rubber cap; the three through holes serve as a test solution injection port, a gas pressure balance port, and a reagent replenishment port, respectively. The step of transferring the supernatant to a cuvette after removing interfering ions through a purification device also includes: Open the rubber cap at the pressure balance port and inject the supernatant through the test solution injection port. After injection, tighten all rubber caps again.

[0011] According to the technical solution provided by the present invention, an external protrusion is provided on one side of the housing, the external protrusion has an opening at the top and extends to the bottom to form a placement groove; a grip handle is provided on the side of the external protrusion away from the housing.

[0012] According to the technical solution provided by the present invention, the fluoride ion colorimetric reagent contains an anti-interference component to eliminate the interference of metal ions in the colorimetric solution on the color development.

[0013] According to the technical solution provided by the present invention, the top of the housing is further provided with a magnetic particle receiving groove, and a magnetic particle is pre-placed in the magnetic particle receiving groove; Before mixing the recycled black powder sample with a measured amount of water in a mixing container, the process further includes: Remove the magnetic particles from the magnetic particle container and place them inside the mixing container.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: The method for detecting water-soluble fluoride ions in recycled black powder provided by this invention is based on a detection device including a shell, a receiving hole, a magnetic stirring module, a placement tank, and a cuvette with built-in colorimetric reagent. By placing the mixing container in the receiving hole for magnetic stirring extraction, the receiving hole provides stable positioning, and the magnetic stirring module directly drives the stirring, enabling rapid on-site extraction of water-soluble fluoride ions without sending samples to the laboratory for processing, effectively shortening the detection cycle; by directly transferring the supernatant to the cuvette in the placement tank after removing interfering ions through a purification device, and mixing and reacting with the built-in colorimetric reagent, there is no need for on-site reagent preparation, simplifying the operation process and reducing the professional skills required of operators; by adopting dual optical path measurements with long and short optical path and establishing a grading judgment standard, the rapid screening efficiency of batch samples and the reliability of detection results are balanced, avoiding misjudgment. In summary, this invention eliminates the need for specialized laboratories and large-scale precision instruments in the entire testing process, enabling it to be completed instantly in scenarios without laboratory conditions, such as ports and trade sites. The testing cycle is shortened from several hours to several days in the prior art to less than one hour, significantly improving on-site testing efficiency. Attached Figure Description

[0015] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart of the steps for detecting water-soluble fluoride ions in recycled black powder provided in Example 1 of this application; Figure 2 This is a schematic diagram of the fluoride ion detection device in Embodiment 1 of this application; Figure 3 for Figure 2 A schematic diagram of the separation of the housing and the top cover in the detection device shown; Figure 4 for Figure 2 A schematic diagram of the structure of the detection device after the cuvette is removed; Figure 5 for Figure 2 A schematic diagram of the cuvette structure in the detection device shown; Figure 6 for Figure 5 A schematic diagram of the structure of the cuvette after the rubber cap has been removed; Figure 7 for Figure 2 A schematic diagram showing the relative positions of the first temperature control module and the second temperature control module in the detection device shown. Figure 8 This is a schematic diagram of the purification device in Embodiment 1 of this application; Figure 9 for Figure 8 A schematic diagram of the liquid outlet end of the purification device shown. Figure 10 for Figure 8 A cross-sectional schematic diagram of the purification device shown. Figure 11 for Figure 8 Schematic diagram of the structure of the medium-filtration membrane module; Figure 12 for Figure 8 The diagram shows the structure of the purification device after connecting the metering pump. Figure 13 This is a schematic diagram of the positioning clip. Figure 14 This is a schematic diagram showing the relative positional relationship between the positioning clamp and the catheter after the clamp has been opened. Figure 15 This is a schematic diagram showing the relative positional relationship between the positioning clamp and the catheter after it has been clamped. Figure 16 A schematic diagram showing the directions of long and short optical path measurements using a spectrophotometer. Figure 17 This is a schematic diagram of the fluoride ion detection device in Embodiment 2 of this application; Figure 18 for Figure 17 A schematic diagram of the separation of the housing and the top cover in the detection device shown; Figure 19 This is a schematic diagram of the fluoride ion detection device in Embodiment 3 of this application; Figure 20 This is a schematic diagram of the fluoride ion detection device in Embodiment 4 of this application; Figure 21 This is a schematic diagram of the positioning clip in Embodiment 5 of this application.

[0016] The text labels in the diagram represent: 1. Shell; 2. Receiving hole; 3. Magnetic stirring module; 4. Placement slot; 5. Cuvette; 6. First temperature control module; 7. Second temperature control module; 8. Top cover; 9. First connecting part; 10. Second connecting part; 11. Weighing part; 12. Display module; 13. Through hole; 14. Rubber cap; 15. External protrusion; 16. Handle; 17. Magnetic particle receiving slot; 18. Elastic pad; 19. Cylinder shell; 20. 21. Inner shell; 22. Outer shell; 23. Receiving space; 24. Elastic pressing part; 25. Limiting part; 26. Filter screen component; 27. Rotating cap; 28. Filter screen; 29. ​​Abutting part; 30. Filter membrane assembly; 31. Fixing frame; 32. Filter membrane; 33. Fixing rib; 34. Elastic sealing ring; 35. Mixed resin filter column; 36. Rotary fastener; 37. Metering pump; 38. Positioning clamp; 39. Clamping part; 40. Elastic element. Detailed Implementation

[0017] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] Example 1 As mentioned in the background section, please refer to the relevant technical issues. Figures 1-16 This embodiment proposes a method for detecting water-soluble fluoride ions in recycled black powder. The method is based on the operation of a fluoride ion detection device. The detection device includes a housing 1, a receiving hole 2 at the top of the housing 1, and a magnetic stirring module 3 inside that is connected to the bottom of the receiving hole 2. A placement groove 4 is provided on one side of the housing 1, and a cuvette 5 containing a built-in fluoride ion colorimetric reagent can be detachably installed in the placement groove 4.

[0020] Specifically, such as Figures 2-4 As shown, the detection device in this embodiment is cup-shaped, with a volume comparable to a regular water cup, making it easy to hold with one hand and carry on-site. The device includes a housing 1, which in this embodiment is a cuboid structure made of lightweight, corrosion-resistant material. A recessed receiving hole 2 is located at the center of the top of the housing 1. The shape of the receiving hole 2 matches the outer contour of the mixing container, serving to limit the movement of the mixing container. In a preferred embodiment, the mixing container is a 50ml volumetric flask with a neck that fits snugly against the opening of the receiving hole 2, preventing the flask from wobbling after insertion.

[0021] A magnetic stirring module 3 is fixedly installed inside the lower part of the housing 1. The top of the magnetic stirring module 3 is directly connected to the bottom of the receiving hole 2, meaning that the rotating magnetic field generated by the magnetic stirring module 3 can penetrate the bottom of the receiving hole 2 and act on the magnetic particles inside the mixing container. A placement groove 4 is provided on one side (e.g., the front or right side) of the housing 1. This placement groove 4 is a blind groove structure with the opening facing upward, and a cuvette 5 is detachably installed inside it. The cuvette 5 can be freely removed and placed from the placement groove 4, facilitating cleaning or replacement before and after detection, and allowing the cuvette 5 to be removed and the solution to be shaken during detection.

[0022] Furthermore, the cuvette 5 provided in this embodiment contains a fluoride ion colorimetric reagent, which is pre-sealed inside the cuvette 5. In use, simply introducing the solution into the cuvette 5 will automatically trigger the colorimetric reaction. To meet the needs of rapid on-site screening, an anti-interference component is specially added to the colorimetric reagent to eliminate the influence of coexisting ions (such as iron, aluminum, calcium, magnesium, etc.) that may be present in the regenerated black powder aqueous solution on the colorimetric reaction. These ions may compete with the fluoride ion colorimetric reagent or form precipitates, resulting in low color intensity or turbidity, thus interfering with the accuracy of the detection results.

[0023] Specifically, the anti-interference component can be selected from one or more combinations of masking agents or ion exchange resin micropowders. For example, adding sodium citrate or triethanolamine can effectively complex iron and aluminum ions, while adding ethylenediaminetetraacetic acid (EDTA) can mask alkaline earth metal ions such as calcium and magnesium. Alternatively, trace amounts of cation exchange resin microbeads can be incorporated to preferentially adsorb interfering ions through ion exchange. The specific formulation of the colorimetric reagent can be optimized and adjusted according to the target fluoride ion concentration range and the types of interfering ions. The alizarin complex ketone-lanthanum nitrate system can be used as the colorimetric reagent, as this system exhibits a good linear relationship between absorbance and fluoride ion concentration at a specific wavelength. It should be noted that only one feasible colorimetric reagent is given here, and the type of colorimetric reagent is not limited. In actual operation, the type of colorimetric reagent can be selected based on the requirements. Pre-packaging can be achieved using vacuum sealing to extend the shelf life of the reagent and ensure good reagent activity during field use. Through the above-mentioned anti-interference design, this detection device can directly perform colorimetric detection on the aqueous extract of regenerated black powder without complex pretreatment, which significantly improves the accuracy and anti-interference ability of the detection and meets the needs of rapid screening of complex sample matrices in ports, trade sites and other places.

[0024] The detection method includes the following steps S100-S400: S100: Mix the recycled black powder sample with a measured amount of water in a mixing container to obtain a mixture.

[0025] Specifically, in step S100, first, add 1 - 2 pre - prepared magnetic stirrers coated with polytetrafluoroethylene into the volumetric flask (usually, 1 magnetic stirrer is sufficient to obtain good stirring effect for a 50 - ml solution), then transfer the sample of the to - be - tested recycled black powder into the volumetric flask, and accurately measure and add distilled water into the volumetric flask with a pipette.

[0026] S200: Place the mixing container into the accommodation hole 2, stir the mixed solution through the magnetic stirring module 3 and then let it stand still to obtain an extract containing a supernatant of water - soluble fluoride ions.

[0027] Specifically, in step S200, first, vertically place the volumetric flask into the accommodation hole 2 at the top of the housing 1. The side wall of the accommodation hole 2 forms a radial limit for the bottom of the volumetric flask to prevent it from eccentrically shaking during the stirring process; then, turn on the magnetic stirring module 3 through the magnetic force adjustment knob (such as the cylindrical structure in front of the detection device shown in Figures 2-4 ), and adjust the stirring speed as needed (for example, set it to 100 r / min). The magnetic stirring module 3 drives the magnetic stirrer in the volumetric flask to rotate, and fully stirs the mixed solution through the movement of the magnetic stirrer to achieve rapid extraction of water - soluble fluoride ions. After the stirring is completed, let it stand still to separate the solid and liquid, and obtain the supernatant.

[0028] S300: After removing interfering ions from the supernatant through the purification device, transfer it into the cuvette 5 so that it is mixed and reacts with the fluoride ion color - developing reagent to obtain a color - developed solution.

[0029] Specifically, in step S300, during the operation, pass the extracted supernatant through the purification device to remove interfering ions such as iron, aluminum, calcium, and magnesium, and then use a liquid transfer tool to transfer it into the cuvette 5 in the placement groove 4. Since the cuvette 5 contains a fluoride ion color - developing reagent, the color - developing reaction is automatically triggered after the test solution is introduced, and there is no need to prepare the reagent on - site.

[0030] S400: Use a spectrophotometer to measure the color - developed solution with a long optical path and a short optical path. If the concentration value measured with the long optical path is less than the preset safety concentration, judge that the sample is qualified; if the concentration value measured with the short optical path is greater than the preset safety concentration, judge that the sample is unqualified; if the preset safety concentration is between the concentration values measured with the long optical path and the short optical path, judge that it needs to be sent to the laboratory for testing.

[0031] Specifically, in step S400, the cuvette 5 adopted in this embodiment has a cuboid structure, and its width direction is the Figure 9 A direction in Figure 9In the B direction of the test, cuvette 5 was placed in the spectrophotometer at different angles to measure the absorbance of the colorimetric solution in cuvette 5 under different optical paths. The detected absorbance was converted into the corresponding fluoride ion concentration value by the built-in calibration curve of the spectrophotometer. In this embodiment, directions A and B were used as the measurement directions, where the optical path length of direction A is 30 mm, corresponding to "long optical path"; and the optical path length of direction B is 10 mm, corresponding to "short optical path". According to the Lambert-Beer law, under the same colorimetric solution and incident light wavelength, absorbance is directly proportional to optical path length. For the same concentration of fluoride ion colorimetric solution, when measured with a 30 mm long optical path, the incident light travels a longer distance through the solution, resulting in a greater absorbance. The concentration value calculated by the spectrophotometer according to the built-in calibration curve should theoretically be three times the concentration value obtained by measuring with a 10 mm short optical path. Based on this principle, this method pre-sets a qualified concentration limit for fluoride ions (i.e., a preset safe concentration). This preset safe concentration is a safety upper limit set for the short optical path measurement mode. In this embodiment, the concentration value measured by the short optical path is used as the actual concentration value of the colorimetric solution, while the concentration value measured by the long optical path is only for the convenience of subsequent judgment and is not the actual concentration value of the colorimetric solution.

[0032] The specific testing method is as follows: First, the colorimetric solution is measured using a short optical path (10mm). If the concentration value obtained from the short optical path measurement is greater than the preset safe concentration, it indicates that the fluoride ion concentration in the sample has exceeded the safety upper limit. The batch of recycled black powder is directly judged to have unqualified water-soluble fluoride ion content and should be sent to the laboratory for precise testing. If the short optical path measurement value does not exceed the preset safe concentration, then a long optical path (30mm) measurement is further performed. The absorbance of the colorimetric solution is greater and the detection sensitivity is higher during long optical path measurement. If the concentration value obtained from the long optical path measurement is still less than the preset safe concentration, it indicates that even under longer optical path and higher sensitivity testing conditions, the fluoride ion concentration is still below the safety limit, thus confirming that the sample is qualified. If the concentration value obtained from the long optical path measurement is greater than the preset safe concentration, i.e., the preset safe concentration is between the short and long optical path measurement values, it indicates that the fluoride ion concentration is within the critical range and needs to be retested or sent to the laboratory for precise confirmation.

[0033] As an example, a preset safe concentration is set at 10.0 mg / L. First, a short-path measurement is performed. If the measured concentration is 12.5 mg / L (greater than 10.0 mg / L), the sample is directly deemed unqualified. If the short-path concentration is 3.2 mg / L (less than 10.0 mg / L), a long-path measurement is performed. If the long-path concentration is 9.8 mg / L (approximately three times the short-path concentration, but less than 10.0 mg / L), the sample is deemed qualified. If the short-path concentration is 8.5 mg / L (less than 10.0 mg / L), and the long-path concentration is 25.2 mg / L (approximately three times the short-path concentration, but greater than 10.0 mg / L), meaning the preset safe concentration of 10.0 mg / L falls between 8.5 mg / L and 25.2 mg / L, then retesting or sending the sample to a laboratory for precise testing is required.

[0034] The core purpose of dual-path measurement is not to repeatedly verify the same concentration, but to utilize the different response characteristics of different optical paths to measurement errors and solution states to construct a "cross-validation and risk grading" mechanism unique to field conditions. In actual field operations, the colorimetric solution may experience local concentration gradients or scattering interference along the optical path due to uneven mixing of the test solution and the colorimetric reagent, insufficient reaction time, or the presence of trace suspended particles in the solution. While a single short-path measurement can reflect the concentration information of a local area of ​​the cuvette, if this area is accidentally too high or too low due to the aforementioned factors, it is very easy to misjudge a qualified sample as unqualified or release a potentially problematic sample. However, with the introduction of long-path measurement, due to the increased optical path, the beam passes through a larger solution volume and a longer path, making its sensitivity to the overall homogeneity and stability of the solution significantly higher than that of short-path measurement. Therefore, by comparing long and short optical paths, this method essentially uses the consistency of dual optical path measurement results as a built-in quality control indicator for "reliability of on-site testing" in the absence of precise mixing and optical conditions in the laboratory. This effectively reduces the risk of misjudgment caused by simplified on-site operation and fluctuations in solution state, and truly achieves a balance between screening efficiency and result reliability.

[0035] Furthermore, such as Figure 7 As shown, the housing 1 also has a first temperature control module 6 inside. The first temperature control module 6 is arranged circumferentially around the receiving hole 2, that is, the first temperature control module 6 has a ring or arc-shaped structure and is attached to the outer wall or bottom of the receiving hole 2. It is used to heat or cool the detection container placed in the receiving hole 2 to maintain a constant temperature of the sample solution during the extraction process.

[0036] In this embodiment, the first temperature control module 6 uses a Peltier temperature controller. Peltier temperature controllers have the advantages of small size, no moving parts, fast response speed, and the ability to both heat and cool. Furthermore, switching between heating and cooling modes can be achieved by changing the direction of the input current, making them suitable for the bidirectional temperature control requirements of portable on-site testing devices.

[0037] In step S200, the step of stirring the mixture using the magnetic stirring module 3 and then allowing it to stand includes: Adjust the first temperature control module 6 to maintain the stirring temperature between 25℃ and 45℃; Control the magnetic stirring module 3 to stir for 20-40 minutes, and then let it stand at the stirring temperature for 2-5 minutes.

[0038] Specifically, in step S200, the temperature of the sample solution in the mixing container is first maintained between 25℃ and 45℃ by adjusting the first temperature control module 6. This temperature range effectively promotes the dissolution of water-soluble fluoride ions from the surface and pores of the regenerated black powder particles into the aqueous phase, while avoiding excessively high temperatures that could lead to degradation of the active ingredients in the subsequent colorimetric reagent, or excessively low temperatures that could reduce extraction efficiency. Experiments show that appropriately increasing the reaction temperature can shorten the extraction and colorimetric time; 25℃-45℃ is the optimal extraction temperature, and the extraction rate of fluoride ions is highest and most stable at 30℃. Subsequently, the magnetic stirring module 3 is controlled to continuously stir at an appropriate speed (e.g., 100 r / min) for 20-40 minutes. The rotation of the magnetic stirrer ensures sufficient contact between the solid and liquid phases, accelerating the dissolution and diffusion of fluoride ions. Too short a stirring time may result in insufficient extraction, while too long a time will affect the efficiency of on-site detection. In this embodiment, 30 minutes is preferred. After stirring, the mixture is allowed to stand for 2-5 minutes at the stirring temperature to allow the solid particles to settle naturally, resulting in solid-liquid separation and the formation of a supernatant. If the settling time is too short, suspended particles may remain in the supernatant; if it is too long, it will delay the overall detection time. In this embodiment, a settling time of 3 minutes is preferred. Through the precise control of temperature and time described above, rapid, efficient, and standardized extraction of water-soluble fluoride ions can be achieved, meeting the timeliness requirements for on-site real-time detection.

[0039] Furthermore, such as Figure 7 As shown, a second temperature control module 7 is also provided inside the housing 1. The second temperature control module 7 is located on the side of the housing 1 near the placement slot 4, and is used to heat or cool the cuvette 5 placed in the placement slot 4 to maintain a constant temperature during the colorimetric reaction process. The second temperature control module 7 and the first temperature control module 6 are synchronously temperature controlled, that is, both are turned on and off simultaneously and adjusted to the same set temperature, thereby ensuring that the magnetic stirring extraction stage and the colorimetric reaction stage are in a consistent constant temperature environment, improving the accuracy and repeatability of the detection results. In this embodiment, both the second temperature control module 7 and the first temperature control module 6 use semiconductor Peltier temperature control chips.

[0040] The first temperature control module 6 and the second temperature control module 7 are powered by a rechargeable lithium battery pack (e.g., multiple 18650 lithium batteries connected in series and parallel) inside the housing 1. This power module also powers the magnetic stirring module 3 and supports simultaneous charging and discharging—it can charge and supply power simultaneously when an external power source is connected, avoiding detection interruption. A temperature adjustment knob (e.g., ...) is located on one side of the housing 1. Figures 2 to 4 The cylindrical structure on the front of the detection device (shown) is electrically connected to the temperature control module's control circuit. It controls the device's on / off state and temperature adjustment. The knob is marked with temperature graduations; rotating it to the desired graduation allows both temperature control modules to simultaneously heat or cool to the set value and maintain a constant temperature. In practical applications, taking a setting of 30℃ as an example: after the temperature control module preheats, a volumetric flask containing the sample solution is placed in the receiving hole 2 for constant-temperature stirring and extraction. The sample solution is then transferred to the cuvette 5 in the placement slot 4. Because the second temperature control module 7 also maintains 30℃, the colorimetric reaction conditions are consistent with the extraction stage, avoiding the influence of temperature fluctuations on the detection results. The simultaneous charging and discharging function further ensures reliable battery life during long-term or continuous testing.

[0041] In step S300, after the supernatant is purified to remove interfering ions and then transferred to cuvette 5, the process further includes: The reaction temperature in cuvette 5 is controlled to be the same as the stirring temperature by the second temperature control module 7, and the reaction is kept at a constant temperature for 5-10 minutes.

[0042] Specifically, after transferring the supernatant to cuvette 5 in step S300, the second temperature control module 7 maintains a constant temperature for the colorimetric solution in cuvette 5, ensuring that the reaction temperature is consistent with the stirring temperature in step S200. Since the second temperature control module 7 and the first temperature control module 6 use synchronous temperature control, they share the same temperature setpoint (e.g., both set to 30℃), eliminating the need for separate on-site adjustment. The reaction is allowed to stand for 5-10 minutes under constant temperature conditions, allowing fluoride ions to fully complex with the colorimetric reagent, forming a stable colored complex. Too short a standing time will result in incomplete color development, affecting measurement accuracy; too long a time will slow down the detection process. In this embodiment, a standing reaction of 10 minutes is preferred, within which the colorimetric reaction reaches equilibrium and the absorbance stabilizes. Maintaining the reaction temperature consistent with the extraction temperature through the second temperature control module 7 avoids deviations in colorimetric intensity caused by temperature fluctuations, ensuring the repeatability and accuracy of the detection results, while also meeting the needs of rapid on-site detection.

[0043] Furthermore, in this embodiment, as Figures 8-11As shown, the purification device includes a shell 19, a filter screen 25, a membrane filter assembly 29, and a mixed resin filter column 34. The shell 19 has an overall cylindrical structure, with a filter screen 25 at its inlet end. The filter screen 25 is used to perform preliminary filtration on the solution entering the shell 19, intercepting large solid particles. The outlet end of the shell 19 is connected to a metering pump 36 via a conduit, which is used to draw the solution. The membrane filter assembly 29 is located inside the shell 19 and can slide relative to the shell 19 along its axial direction. This sliding design allows the membrane filter assembly 29 to be installed, disassembled, or replaced without tools, simplifying operation and facilitating rapid on-site maintenance.

[0044] like Figure 10 As shown, the internal structure of the cylindrical shell 19 contains, sequentially along the axial direction, a filter screen 25, a filter membrane assembly 29, and a mixed resin filter column 34. The mixed resin filter column 34 is positioned on the side of the filter membrane assembly 29 near the liquid outlet, with its end face abutting against the end face of the filter membrane assembly 29. Simultaneously, the filter screen 25 applies a clamping force to the filter membrane assembly 29 from the liquid inlet, thereby cooperating with the mixed resin filter column 34 to clamp and fix the filter membrane assembly 29 between them. This ensures that the filter membrane assembly 29 does not shift or deviate during solution flow, guaranteeing filtration stability. The mixed resin filter column 34 is used to adsorb metal ions in the solution, especially ions such as iron, aluminum, calcium, and magnesium, which may interfere with the subsequent fluoride ion colorimetric reaction, thus significantly improving detection accuracy.

[0045] As a feasible specific implementation, the mixed resin filter column 34 can be prepared by filling the interior of a columnar shell with a chelating ion exchange resin. For example, a filter column shell made of polypropylene can be selected, and the interior can be filled with an iminodiacetic acid-type chelating resin (such as Amberlite IRC-748). This resin has a high selective adsorption capacity for transition metal ions, but almost no adsorption for fluoride ions. During filling, porous sieve plates are set at both ends of the resin to prevent resin leakage and ensure that the solution can flow smoothly. In use, the supernatant first passes through the filter screen 25 and the filter membrane assembly 29 to remove solid particles, and then enters the mixed resin filter column 34. The metal interfering ions are adsorbed and retained by the resin, and the purified solution flows out from the outlet end to enter the subsequent detection stage.

[0046] Furthermore, the liquid outlet of the shell 19 is detachably connected to the conduit, facilitating rapid on-site assembly or replacement of the conduit and improving the portability and adaptability of the device. Specifically, for example... Figures 9-10As shown, the liquid outlet end of the cylindrical shell 19 includes an inner shell 20 and an outer shell 21 arranged coaxially. The inner shell 20 is located inside the outer shell 21, forming an annular receiving space 22 between them. This receiving space 22 is used to receive and position the conduit for conveying the solution. The inner shell 20 is a hollow tubular structure, and its internal channel communicates with the internal chamber of the cylindrical shell 19. The end of the inner shell 20 near the filter screen 25 is fixedly connected to the inner wall of the outer shell 21, closing the end of the receiving space 22 near the filter screen 25, while the end of the receiving space 22 away from the filter screen 25 remains open for the insertion of the conduit. The end of the conduit is sleeved on the outside of the inner shell 20, and the outer wall of the conduit contacts the inner wall of the outer shell 21, thereby achieving stable positioning of the conduit. At this time, the solution purified by the filter screen 25, the filter membrane assembly 29, and the mixed resin filter column 34 can directly enter the interior of the conduit through the inner channel of the inner shell 20, achieving leak-free delivery of the solution.

[0047] The outer shell 21 has at least two elastic clamping parts 23. In this embodiment, there are two elastic clamping parts 23, which are symmetrically arranged along the circumference of the cylindrical shell 19, i.e., they are spaced 180 degrees apart. The elastic clamping parts 23 are formed by axially opening narrow slots in the side wall of the outer shell 21, and have a certain radial elastic deformation capability. A rotating fastener 35 is fitted on the outside of the cylindrical shell 19. The inner wall of the rotating fastener 35 has an internal thread, and the outer wall of the cylindrical shell 19 has a corresponding external thread. The external thread extends from the main body of the cylindrical shell 19 to the outer walls of the outer shell 21 and the elastic clamping parts 23. When the rotating fastener 35 is tightened along the thread, its inner wall gradually compresses the two elastic clamping parts 23 radially inward, thereby symmetrically clamping the conduit inserted into the receiving space 22 from both sides. When the rotating fastener 35 is loosened, the elastic clamping parts 23 return to their original shape by their own elasticity, releasing the clamping of the conduit, which facilitates the insertion and removal of the conduit. The two symmetrically arranged elastic clamping parts 23 can provide uniform clamping force, preventing the conduit from becoming misaligned or not sealing properly due to force on one side.

[0048] Furthermore, such as Figures 8-10 As shown, a protruding limiting part 24 is provided on the outer wall of the end of the elastic pressing part 23 away from the filter screen 25. The limiting part 24 may be a protrusion or rib structure integrally formed with the elastic pressing part 23, and its radial dimension is larger than the outer diameter of the rest of the elastic pressing part 23. When the rotating fastener 35 is tightened towards the liquid outlet end until it touches the limiting part 24, the limiting part 24 prevents it from moving further, thereby preventing the rotating fastener 35 from falling off due to excessive rotation.

[0049] Furthermore, such as Figure 10 and Figure 11As shown, the filter membrane assembly 29 includes a fixing frame 30 and a filter membrane 31. The fixing frame 30 has a circular structure and is made of corrosion-resistant materials such as polypropylene or polytetrafluoroethylene. The filter membrane 31 is fixedly installed in the inner ring of the fixing frame 30. The filter membrane 31 can be a mixed cellulose ester membrane or a polyethersulfone membrane, and the pore size is preferably 0.45 μm or 0.22 μm, used to intercept tiny suspended particles in the solution.

[0050] like Figure 11 As shown, the fixing frame 30 has cross-shaped fixing ribs 32 on both sides of the filter membrane 31, one on the inlet side and one on the outlet side of the filter membrane 31. The center of the cross on the fixing rib 32 corresponds to the center of the filter membrane 31, and its end is connected to the inner wall of the fixing frame 30. The function of the fixing rib 32 is to limit the filter membrane 31, preventing excessive deformation or damage to the filter membrane 31 under the pressure generated by the flow of solution, while maintaining the flatness of the filter membrane 31 within the fixing frame 30. It should be noted that the fixing rib 32 only contacts and limits the surface of the filter membrane 31, and is not connected or bonded to the filter membrane 31. When it is necessary to remove the filter membrane assembly 29 from the shell 19, the operator can use a hook or tweezers to hook the center of the cross-shaped fixing rib 32 or any branch, and then easily pull the filter membrane assembly 29 out axially.

[0051] Furthermore, such as Figure 10 and Figure 11 As shown, an annular elastic sealing ring 33 is fitted around the outer ring of the fixing frame 30. The elastic sealing ring 33 is preferably an O-ring made of silicone rubber or fluororubber, and its inner diameter is adapted to the annular groove on the outer ring of the fixing frame 30, fitting into the groove to prevent it from falling out. When the filter membrane assembly 29 is installed inside the shell 19, the outer wall of the elastic sealing ring 33 forms a radial compression contact with the inner wall of the shell 19, thereby creating a reliable sealing interface between the fixing frame 30 and the shell 19.

[0052] Furthermore, such as Figure 8 and Figure 10As shown, the filter element 25 includes a rotating cap 26, which has a round cap-like structure and an internal thread on its inner wall. This thread engages with the external thread on the outer wall of the liquid inlet end of the cylinder shell 19, enabling a detachable threaded connection. A filter screen 27 is fixed at the center of the rotating cap 26. The filter screen 27 can be made of stainless steel wire mesh or nylon mesh, with a preferred pore size of 100 to 200 mesh. It is used to intercept large solid particles in the solution, preventing them from entering the cylinder shell 19 and clogging the filter membrane assembly 29 or the mixed resin filter column 34. A cylindrical abutment portion 28 is provided on the rotating cap 26 around the filter screen 27. The abutment portion 28 extends from the inner wall of the rotating cap 26 toward the interior of the cylindrical shell 19. Its outer wall is clearance-fitted with the inner wall of the cylindrical shell 19, allowing the abutment portion 28 to smoothly extend into the inner cavity of the cylindrical shell 19 and press and fix the filter membrane assembly 29 to one end of the mixed resin filter column 34. This clamps and fixes the filter membrane assembly 29 between the abutment portion 28 of the filter screen 25 and the mixed resin filter column 34. A sealing ring can be provided between the rotating cap 26 and the cylindrical shell 19 to improve the connection sealing.

[0053] Furthermore, a positioning clamp 37 is fitted onto the conduit connecting the liquid outlet end of the connecting cylinder 19 and the metering pump 36, such as... Figures 12-13 The positioning clip 37 includes a pair of clamping parts 38 and a pair of pressing parts 39. The pair of clamping parts 38 are arranged opposite each other and connected to form a rhomboid ring structure. Of the four vertices of this rhomboid ring structure, two opposite vertices are connected to the pair of pressing parts 39, and the other two opposite vertices form a clamping surface for clamping the tubing. The clamping surface is provided with anti-slip texture to increase the friction between the positioning clip 37 and the tubing, preventing relative displacement of the tubing due to slight tension or vibration during pipetting. The positioning clip 37 has a specially designed structure: the inner diameter of its clamping part 38 is slightly smaller than the outer diameter of the tubing in its natural state, and the clamping surface of the clamping part 38 adopts an arc-shaped or planar structure, so that the clamping force is evenly distributed around the circumference of the tubing, which can firmly clamp the tubing without crushing or cutting the tubing due to excessive local pressure, ensuring smooth flow of solution in the tubing.

[0054] like Figure 13 As shown, in its natural state, the rhomboid annular structure is in a contracted state, and the inner diameter between its clamping surfaces is slightly smaller than the outer diameter of the catheter, thus achieving clamping of the catheter. Figure 14 As shown, when the operator presses the pair of pressing parts 39 inward with their fingers, the pressing parts 39 drive the clamping parts 38 to open outward against the elasticity of the material, causing the rhomboid ring structure to deform and its inner diameter to expand. At this time, the positioning clamp 37 can slide freely along the guide tube. Figure 15 As shown, when the pair of pressing parts 39 are released, the clamping part 38 returns to its original elasticity, the rhomboid ring structure returns to its natural contracted state, re-clamps the tube, and the positioning clamp 37 is automatically placed in the clamping state.

[0055] In step S300, the step of transferring the supernatant to cuvette 5 after removing interfering ions through a purification device includes: The guide tube is fixed to the container opening of the mixing container by the positioning clamp 37, so that the liquid inlet of the purification device is suspended in the supernatant, and the rear guide tube of the metering pump 36 is inserted into the liquid injection port of the cuvette 5. Start metering pump 36 to perform the first filtration, discard the resulting liquid, and activate the mixed resin filter column 34 and clean the pipeline. The metering pump 36 is restarted for a second filtration, allowing the supernatant to flow sequentially through the filter screen, filter membrane, and mixed resin filter column 34 before being directly introduced into the cuvette 5.

[0056] Specifically, in step S300, the position of the positioning clip 37 is first adjusted to ensure that when the positioning clip 37 is placed at the opening of the mixing container, the inlet of the purification device is suspended at an appropriate depth below the surface of the supernatant (e.g., 2 cm below the surface) to avoid aspirating bottom sediment. At the same time, the conduit at the rear end of the metering pump 36 is inserted into the cuvette 5. Then, the metering pump 36 is started for the first filtration, and about 10 ml of liquid is drawn and discarded. This operation, on the one hand, uses the test solution to wet and activate the mixed resin filter column 34, so that the ion exchange resin in it is fully exposed; on the other hand, it cleans the pipeline and purification device to eliminate any possible contamination. Then, the metering pump (36) is started again for the second filtration, so that the supernatant flows through the filter screen 25, the filter membrane assembly 29 and the mixed resin filter column 34 in sequence. During this process, impurities are intercepted by the filter screen 25 and the filter membrane assembly 29, and metal interfering ions are adsorbed by the mixed resin filter column 34. The purified test solution is directly introduced into the cuvette 5 and mixed with the built-in colorimetric reagent. The entire process requires no manual filtration or transfer, achieving closed-loop and automated purification and sample introduction, reducing the risk of operational contamination, and improving the convenience and repeatability of on-site testing. In this embodiment, the metering pump 36 can be a metering pump with quantitative dilution function, used to dilute the supernatant while extracting it, avoiding excessively high supernatant concentration exceeding the upper limit of colorimetric detection, thus affecting the detection results; or a conventional metering pump 36 can be used, and the supernatant can be diluted by other means between the rear end of the metering pump 36 and the cuvette 5.

[0057] Further, in step S100, before mixing the regenerated black powder sample with a measured amount of water in a mixing container, the process further includes: Take a representative sample of recycled black powder, at least 500g, divide it evenly into multiple portions, and mix the sample from each portion. Weigh 5g of the mixed recycled black powder sample into a mixing container and add distilled water to the mixing container.

[0058] Specifically, to ensure the representativeness of the samples, at least 500g of recycled black powder from the batch to be tested is first taken, spread out, and evenly divided into multiple portions (e.g., 20 portions) using a quartering or equal division method. Then, approximately 1g of sample is taken from each portion and combined in a clean container, then thoroughly mixed. This multi-point sampling method effectively avoids deviations in fluoride ion content caused by uneven distribution of recycled black powder particles, ensuring that the test results accurately reflect the quality level of the entire batch of samples. Subsequently, 5g of the mixed sample is quantitatively weighed using the weighing module integrated in the top cover 8 and placed in a volumetric flask. This sampling volume is optimized to ensure both detection sensitivity and ease of rapid on-site operation. Finally, distilled water is added to the mixing container to the predetermined mark (usually 50ml) to form a 1:10 solid-liquid ratio, allowing water-soluble fluoride ions to dissolve fully. The above pretreatment steps are simple to operate, time-saving, and do not require complex laboratory equipment, meeting the timeliness requirements of on-site rapid screening for sample preparation.

[0059] Furthermore, such as Figures 2-3 As shown, a top cover 8 is also provided on the top of the housing 1. The size of the top cover 8 is adapted to the overall outer contour of the housing 1. The top cover 8 and the housing 1 are detachably connected through a mutually fitting connection structure. Specifically, the top of the housing 1 is provided with a protruding first connecting part 9, and the bottom surface of the top cover 8 is provided with a corresponding recessed second connecting part 10. The shapes of the first connecting part 9 and the second connecting part 10 match each other. The top cover 8 and the housing 1 are quickly and stably detachably connected by inserting the first connecting part 9 into the second connecting part 10. The detection device is cup-shaped overall, and the top cover 8 is equivalent to the lid of the cup-shaped structure. When the top cover 8 is closed on the top of the housing 1, since the coverage area of ​​the top cover 8 matches the opening area of ​​the top of the housing 1, the opening of the receiving hole 2 is naturally completely covered by the top cover 8, while the placement slot 4 located on one side of the housing 1 is not covered by the top cover 8 and remains open.

[0060] The top cover 8 is mainly used for the storage and protection of the testing device when it is not in use: when the device is not in use, closing the top cover 8 can effectively prevent external dust and impurities from falling into the receiving hole 2, and at the same time prevent foreign objects from entering the hole and causing contamination or damage to the magnetic stirring module 3, thus playing a dustproof and protective role. When on-site testing is required, the operator first removes the top cover 8 from the housing 1 (by separating the first connecting part 9 from the second connecting part 10), and then places the testing container (such as a volumetric flask) containing the sample solution into the receiving hole 2. Since the bottleneck of the volumetric flask is usually higher than the top surface of the housing 1, the top cover 8 cannot be closed again after the testing container is placed in. Therefore, the top cover 8 remains in the removed state during the magnetic stirring extraction process, which does not hinder the operator from observing the stirring status or performing subsequent liquid addition operations.

[0061] Furthermore, such as Figure 3As shown, in the detection device provided in this embodiment, in order to achieve a stable and easy-to-operate connection between the upper cover 8 and the housing 1, the first connecting part 9 and the second connecting part 10 adopt the following specific structure.

[0062] At least two first connecting portions 9 are provided, preferably two in this embodiment. The two first connecting portions 9 are symmetrically arranged on opposite sides of the top edge of the housing 1 about the central axis of the receiving hole 2. Each first connecting portion 9 is block-shaped or columnar and protrudes vertically upward from the top surface of the housing 1. The side wall of the first connecting portion 9 away from the housing 1 is provided with an outwardly protruding arc-shaped snap-fit ​​portion, the outer contour of which is arc-shaped or hemispherical, for forming a snap-fit ​​engagement with the second connecting portion 10.

[0063] Correspondingly, the second connecting part 10 is disposed at the bottom edge of the upper cover 8, and its position and number correspond one-to-one with the first connecting parts 9. The second connecting part 10 is a concave groove or hole, and its inner wall shape matches the arc-shaped locking part of the first connecting part 9. When the upper cover 8 is closed downwards, the arc-shaped locking part of the first connecting part 9 is compressed and undergoes elastic deformation. After the locking part enters the second connecting part 10, it returns to its original shape, achieving a firm locking connection. Since the two first connecting parts 9 are symmetrically arranged, the upper cover 8 is subjected to uniform force when closed, and it is not easy to become skewed or loose. When it is necessary to open the upper cover 8, the operator only needs to pull the upper cover 8 upwards with force, so that the arc-shaped locking part overcomes the elastic force and disengages from the second connecting part 10, and can be easily separated.

[0064] Furthermore, such as Figures 2 to 4 As shown, a weighing module (not shown) is disposed inside the upper cover 8. This weighing module is preferably a miniature electronic weighing sensor, such as a resistance strain gauge sensor or a pressure capacitive sensor. A weighing section 11 is disposed on the top surface of the upper cover 8, which corresponds to the force-bearing area of ​​the weighing module and is used to place the sample container or sample to be weighed. A display module 12 is also disposed on the top surface of the upper cover 8. The display module 12 is electrically connected to the weighing module and is used to display the weight value measured by the weighing module in real time. The display module 12 is preferably a liquid crystal display (LCD) or a digital tube display screen, which can clearly display the reading.

[0065] In use, the operator can remove the top cover 8 from the housing 1 and use it as a portable electronic scale. Because the second connecting part 10 has a concave structure (i.e., a concave groove on the bottom surface of the top cover 8), the bottom surface of the top cover 8 remains completely flat, without any protruding obstacles. Therefore, during weighing, the operator can place the top cover 8 directly on a table or other level surface, with the bottom surface making stable contact with the surface. This prevents wobbling or tilting due to the connecting part structure, ensuring the accuracy of the weighing results.

[0066] In practical applications, during sample collection in the testing process, the operator can remove the top cover 8 and place it flat on the table. An empty sample container (such as a weighing boat or beaker) is placed on the weighing unit 11. The tare weight is read and zeroed via the display module 12. Then, the regenerated black powder sample is added to the required mass, achieving rapid and accurate on-site weighing. After weighing, the top cover 8 is simply replaced with the housing 1 for storage, without taking up extra space. Because the weighing module is integrated into the top cover 8, there is no need to carry a separate electronic balance, further reducing the number of devices required for on-site testing and improving portability and operational efficiency.

[0067] The quantitative weighing of 5g of recycled black powder sample includes: Remove the top cover 8 from the housing 1 and lay it flat. Place the sample container on the weighing part 11 and read and weigh the required mass of the recycled black powder sample through the display module 12.

[0068] Specifically, in the sample weighing step S100, the operator first removes the top cover 8 from the housing 1. Since the bottom surface of the top cover 8 has a recessed second connecting part 10, the entire structure remains flat and can be placed directly on a table or other level surface without additional support. An empty sample container (such as a weighing boat or beaker) is placed on the weighing unit 11, and the tare weight is read through the display module 12 and the zeroing button is pressed. Then, the regenerated black powder sample is added to the sample container using a spatula or sampling spoon, while simultaneously observing the reading on the display module 12, until the required mass of 5g is reached. The weighing module uses a miniature electronic weighing sensor with an accuracy of 0.01g, meeting the requirements for on-site weighing. After weighing, the container containing the sample is removed for subsequent mixing steps.

[0069] Furthermore, such as Figure 5 and Figure 6 As shown, the cuvette 5 has at least three through holes 13 communicating with the interior, and each through hole 13 is provided with a removable rubber cap 14. The rubber cap 14 is made of elastic material (such as silicone rubber or fluororubber) and is tightly inserted into the through hole 13 to seal and prevent leakage; it can be manually removed or replaced as needed during use, making the operation simple.

[0070] The three through holes 13 each serve a different function: The first through-hole 13 serves as the test solution injection port, used to add the test solution into the cuvette 5. During operation, the operator removes the rubber cap 14 from the through-hole 13 and uses a pipette or pipette tube to quantitatively inject the filtered extract into the cuvette 5. After injection, the rubber cap 14 is replaced to seal the cuvette and prevent liquid leakage or external contaminants from entering.

[0071] The second through-hole 13 serves as a pressure balancing hole, used to balance the internal and external air pressure of cuvette 5 when adding the test solution. Since cuvette 5 is pre-sealed with a colorimetric reagent and initially sealed, without the pressure balancing hole, the compressed internal gas would obstruct the smooth flow of the test solution during injection. The operator can remove the rubber cap 14 on this through-hole 13 before or during injection to allow the internal gas to escape smoothly, eliminating back pressure and ensuring the test solution can be added to cuvette 5 steadily and quickly. After adding the solution, the rubber cap 14 should be replaced.

[0072] The third through-hole 13 serves as a reagent replenishment port, used to replenish the reagent when the anti-interference component or colorimetric reagent is insufficient. In certain special cases, such as when the fluoride ion concentration in the sample exceeds the original detection range, or when the reagent activity decreases due to improper storage, the operator can add anti-interference masking agent or concentrated colorimetric reagent to the cuvette 5 through this through-hole 13, thereby expanding the detection range or restoring the colorimetric ability, and improving the applicability and flexibility of the device.

[0073] In step S300, the step of transferring the supernatant to cuvette 5 after removing interfering ions through a purification device further includes: Open the rubber cap 14 at the air pressure balance port, inject the supernatant through the test liquid injection port, and then tighten all the rubber caps 14 again after injection.

[0074] Specifically, in step S300, when introducing the purified supernatant into the cuvette 5, the operator first removes the rubber cap 14 from the through-hole 13, which serves as the pressure balance port, allowing the cuvette 5 to communicate with the atmosphere and eliminating internal pressure resistance caused by the seal. Then, the rubber cap 14 from the through-hole 13, which serves as the test solution injection port, is removed, and the conduit at the rear end of the metering pump 36 is inserted into the test solution injection port. The metering pump 36 is then started to inject the supernatant. Since the pressure balance port is open, the test solution can flow smoothly into the cuvette 5 without back pressure or bubbles due to gas compression. After injection, the rubber caps 14 of both the test solution injection port and the pressure balance port are tightened again to ensure the cuvette 5 is sealed, preventing liquid leakage or the entry of external contaminants. If insufficient activity of the colorimetric reagent is found during the detection process, or if an expanded detection range is needed, additional masking agent or concentrated colorimetric reagent can be added through the reagent replenishment port. This multi-port design ensures smooth test solution transfer and reliable sealing, while retaining the ability to flexibly adjust reagents on-site, improving the adaptability and convenience of the detection method.

[0075] Furthermore, such as Figures 2 to 4As shown, an external protrusion 15 is provided on one side of the housing 1. This external protrusion 15 extends horizontally outward from the side wall of the housing 1, and its overall shape is a rectangular or circular block structure with an open top. The interior of the external protrusion 15 extends downward from the top opening to form a hollow placement groove 4. The depth of the placement groove 4 matches the height of the cuvette 5, and is used to accommodate and position the cuvette 5. Since the placement groove 4 is located on the outwardly protruding external protrusion 15, the cuvette 5 is located on the side of the housing 1 after installation. This does not affect the receiving hole 2 at the top of the housing 1 for placing volumetric flasks and other testing containers, and it is also convenient for operators to take the cuvette 5 out from the side. This achieves spatial separation and reasonable layout of the magnetic stirring station and the colorimetric testing station.

[0076] In this embodiment, the external protrusion 15 and the housing 1 are manufactured using an integral molding process, that is, by injection molding or casting to form a single structure, ensuring connection strength, sealing performance, and the overall aesthetics of the device. Alternatively, the external protrusion 15 and the housing 1 can be detachably connected. For example, the side wall of the housing 1 is provided with a slot or threaded interface, and the corresponding position of the external protrusion 15 is provided with a snap-fit ​​or threaded connector, fixing the external protrusion 15 to the housing 1 by snap-fit ​​or screw-fit. When a component is damaged, it can be replaced individually, or different specifications of the external protrusion 15 can be replaced according to different cuvette 5 sizes, improving the flexibility and maintainability of the device.

[0077] Furthermore, such as Figures 2 to 4 As shown, a grip handle 16 is provided on the side of the external protrusion 15 away from the housing 1, that is, on the outer side wall of the external protrusion 15. The two ends of the grip handle 16 are respectively fixed to the upper and lower ends of the outer side wall of the external protrusion 15, and the middle part forms a gripping space for fingers to pass through. The outer surface of the grip handle 16 may be provided with anti-slip texture or covered with an anti-slip rubber layer to increase friction and comfort when gripping.

[0078] By providing a grip handle 16 on the external protrusion 15, the operator can lift the entire device by holding the grip handle 16 with one hand when moving the detection device on site, without having to touch the main body of the housing 1 or the detection container inside the receiving hole 2, thus avoiding the influence of hand temperature on the sample solution temperature or the shaking of the container due to contact.

[0079] Example 2 Please refer to Figures 17-18 Based on Example 1 above, this example provides another method for detecting water-soluble fluoride ions in recycled black powder. This example is the same as Example 1 in the method part; the similarities will not be repeated here. The differences are as follows: In this embodiment, the first connecting part 9 is annular and distributed around the receiving hole 2, and the second connecting part 10 is annular and corresponds to the first connecting part 9; the outer ring sidewall of the first connecting part 9 is provided with a first thread, and the inner wall of the second connecting part 10 is provided with a second thread corresponding to the first connecting part 9.

[0080] Specifically, the first connecting part 9 is a circular protrusion surrounding the accommodating hole 2, extending continuously circumferentially from the top of the housing 1 to form a complete annular boss. The outer sidewall of this annular boss has a first thread (i.e., an external thread). The second connecting part 10 is located at the bottom edge of the upper cover 8, forming a circular groove structure, corresponding to and matching the size of the first connecting part 9. The inner wall of the second connecting part 10 has a second thread (i.e., an internal thread) that engages with the first thread. When the upper cover 8 needs to be placed on the housing 1, the operator aligns the upper cover 8 with the top of the housing 1, allowing the second connecting part 10 to fit over the first connecting part 9, and then rotates the upper cover 8 clockwise. The internal and external threads work together to achieve a tight connection. Conversely, rotating the upper cover 8 counterclockwise allows for easy removal.

[0081] Example 3 Please refer to Figure 19 Based on Example 1 above, this example provides another method for detecting water-soluble fluoride ions in recycled black powder. This example is the same as Example 1 in the method part; the similarities will not be repeated here. The differences are as follows: In this embodiment, the inner wall of the top end of the receiving hole 2 is provided with an annular elastic pad 18.

[0082] Specifically, the elastic pad 18 is preferably made of a material with a certain compression deformation capacity, such as silicone rubber, fluororubber or polyurethane elastomer. Its outer ring is tightly fitted to the inner wall of the receiving hole 2 and can be fixed by adhesive or pressing.

[0083] In this embodiment, the elastic pad 18 serves a dual purpose. First, when the operator places a volumetric flask or other testing container into the receiving hole 2, the neck or body of the flask will first contact the elastic pad 18. Because the elastic pad 18 is soft and has cushioning properties, it effectively prevents the glass volumetric flask from directly impacting the hard edge of the housing at the opening of the receiving hole 2, thereby reducing the risk of container breakage and protecting the opening edge of the receiving hole 2 from wear. Second, after installation, the upper surface of the elastic pad 18 is slightly higher than the opening end face of the receiving hole 2, causing a portion of the elastic pad 18 to protrude from the top surface of the housing 1. When the top cover 8 is closed with the housing 1, the bottom surface of the inner wall of the top cover 8 will form a pressing contact with the protruding elastic pad 18. The elastic pad 18 is compressed and generates a rebound force, thus forming an elastic sealing barrier between the top cover 8 and the receiving hole 2.

[0084] Example 4 Please refer to Figure 20 Based on Example 1 above, this example provides another method for detecting water-soluble fluoride ions in recycled black powder. The same content as in Example 1 will not be repeated here; the difference lies in: The top of the housing 1 is also provided with a magnetic particle receiving groove 17, in which magnetic particles are pre-placed.

[0085] Specifically, the magnetic spool 17 is a small blind groove or recess on the top surface of the housing 1. Its size and shape match the polytetrafluoroethylene-coated magnetic spool, for example, it is a cylindrical or elliptical sunken space with a depth slightly greater than the diameter of the magnetic spool and a width slightly greater than the length of the magnetic spool, so that the magnetic spool can be smoothly placed in and taken out.

[0086] The main function of the magnetic particle receiving tank 17 is to provide a dedicated place for magnetic particles in the testing device, eliminating the need for operators to prepare magnetic particles separately. Since magnetic stirring is a crucial step in the extraction of water-soluble fluoride ions, and magnetic particles, as stirring elements, are essential consumables for testing, the magnetic particle receiving tank 17, located directly on the top of the housing 1, allows standard-sized magnetic particles to be pre-placed at the factory. During field use, operators can simply remove the magnetic particles from the tank and place them directly into the testing container, eliminating the need for separate purchase, carrying, or searching for magnetic particles, greatly facilitating rapid on-site testing. Simultaneously, the magnetic particle receiving tank 17 also serves a storage and anti-loss function: after testing or when the device is stored, the cleaned magnetic particles can be returned to the tank, effectively preventing loss due to their small size and ensuring they are still intact for the next use.

[0087] Before mixing the recycled black powder sample with a measured amount of water in a mixing container, the process further includes: Remove the magnetic particle from the magnetic particle receiving tank 17 and place it inside the mixing container.

[0088] Example 5 Please refer to Figure 21 Based on Example 1 above, this example provides another method for detecting water-soluble fluoride ions in recycled black powder. This example is the same as Example 1 in the method part; the similarities will not be repeated here. The differences are as follows: An elastic element 40 is also connected between the pair of clamping parts 38. The elastic element 40 is used to drive the pair of clamping parts 38 to reset when the pair of pressing parts 39 are released.

[0089] Specifically, in this embodiment, an elastic element 40 is also connected between the pair of clamping portions 38, with its two ends respectively fixed to the opposite inner sides of the two clamping portions 38. When the operator presses the pair of pressing portions 39 to open the clamping portions 38, the elastic element 40 is stretched and elastically deformed, storing elastic potential energy; when the pair of pressing portions 39 are released, the elastic element 40 releases the stored elastic potential energy, causing the pair of clamping portions 38 to quickly return to their initial position, thereby enhancing or assisting the reset action of the clamping portions 38 and ensuring that the positioning clamp 37 reliably switches to the clamping state. Figure 21 As shown, the elastic element 40 can be a miniature tension spring, with its two ends hooked onto the lugs provided on the inner side of the two clamping parts 38, which has a compact structure and does not affect the overall shape of the positioning clamp 37.

[0090] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for detecting water-soluble fluoride ions in recycled black powder, characterized in that, Based on the operation of a fluoride ion detection device, the detection device includes a housing (1). The top of the housing (1) is provided with a receiving hole (2), and a magnetic stirring module (3) docked with the bottom end of the receiving hole (2) is arranged inside. On one side of the housing (1), there is a placement groove (4), and a colorimetric cell (5) containing a fluoride ion chromogenic reagent is detachably installed in the placement groove (4). The method includes: Mix a regenerated black powder sample with a quantified amount of water in a mixing container to obtain a mixed solution. Place the mixing container in the receiving hole (2), stir the mixed solution through the magnetic stirring module (3), and then let it stand to obtain an extract containing a water-soluble fluoride ion supernatant. After removing interfering ions from the supernatant through a purification device, transfer it to the colorimetric cell (5) so that it mixes and reacts with the fluoride ion chromogenic reagent to obtain a colored solution. Use a spectrophotometer to perform long-path and short-path measurements on the colored solution. If the concentration value measured in the long path is less than the preset safety concentration, judge that the sample is qualified. If the concentration value measured in the short path is greater than the preset safety concentration, judge that the sample is unqualified. If the preset safety concentration is between the concentration values measured in the long path and the short path, judge that it needs to be sent to the laboratory for testing.

2. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 1, characterized in that, Inside the housing (1), there is also a first temperature control module (6) and a second temperature control module (7). The first temperature control module (6) is arranged circumferentially around the side wall of the receiving hole (2), and the second temperature control module (7) is arranged on one side of the housing (1) close to the placement groove (4). The second temperature control module (7) adjusts the temperature synchronously with the first temperature control module (6). The step of stirring the mixed solution through the magnetic stirring module (3) and then letting it stand includes: Adjust the first temperature control module (6) to maintain the stirring temperature at 25°C - 45°C.

3. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 2, characterized in that, Control the magnetic stirring module (3) to stir for 20 min - 40 min, and after stirring, let it stand at the stirring temperature for 2 min - 5 min. The purification device includes: A cylinder shell (19). The liquid inlet end of the cylinder shell (19) is provided with a filter element (25), and the liquid outlet end is connected to a metering pump (36) through a conduit. A positioning clamp (37) is arranged on the conduit. A filter membrane assembly (29). The filter membrane assembly (29) is arranged inside the cylinder shell (19) and can slide relative to the cylinder shell (19) along the axial direction of the cylinder shell (19). A mixed resin filter column (34). The mixed resin filter column (34) is arranged inside the cylinder shell (19) and is located between the liquid outlet end and the filter membrane assembly (29). The mixed resin filter column (34) cooperates with the filter element (25) to clamp and fix the filter membrane assembly (29). The mixed resin filter column (34) is used to adsorb metal ions in the solution. The step of transferring the supernatant to the colorimetric cell (5) after removing interfering ions through the purification device includes: Fix the conduit to the container mouth of the mixing container through the positioning clamp (37) so that the liquid inlet of the purification device is suspended in the supernatant, and insert the conduit at the rear end of the metering pump (36) into the liquid injection port of the colorimetric cell (5). Start the metering pump (36) for the first suction filtration, and discard the obtained liquid to activate the mixed resin filter column (34) and clean the pipeline. The metering pump (36) is restarted for a second filtration, so that the supernatant flows through the filter screen (25), the filter membrane assembly (29) and the mixed resin filter column (34) in sequence, and is then directly introduced into the cuvette (5).

4. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 3, characterized in that, The liquid outlet end of the cylindrical shell (19) includes an inner shell (20) and an outer shell (21) arranged coaxially. A conduit-accommodating space (22) is formed between the inner shell (20) and the outer shell (21). The end of the inner shell (20) near the filter screen (25) is fixedly connected to the inner wall of the outer shell (21) and closes one end of the accommodating space (22). The outer shell (21) has at least two elastic clamping parts (23), which are evenly distributed around the cylindrical shell (19). A rotating fastener (35) is sleeved on the outside of the cylindrical shell (19). The inner wall of the rotating fastener (35) is threaded to the external thread of the outer wall of the cylindrical shell (19), and the external thread extends to the outer wall of the outer shell (21) and the elastic clamping part (23).

5. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 1, characterized in that, Before mixing the recycled black powder sample with a measured amount of water in a mixing container, the process further includes: Take a representative sample of recycled black powder, at least 500g, divide it evenly into multiple portions, and mix the sample from each portion. Weigh 5g of the mixed recycled black powder sample into a mixing container and add distilled water to the mixing container.

6. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 1, characterized in that, The top of the housing (1) is also provided with a top cover (8), the top of the housing (1) is provided with a first protruding connecting part (9), and the bottom surface of the top cover (8) is provided with a second concave connecting part (10) corresponding to the first connecting part (9). The top cover (8) and the housing (1) are detachably connected through the cooperation of the first connecting part (9) and the second connecting part (10). The top cover (8) is provided with a weighing module inside, and the top surface of the top cover (8) is provided with a weighing part (11) corresponding to the weighing module and a display module (12) electrically connected to the weighing module. The quantitative weighing of 5g of recycled black powder sample includes: Remove the top cover (8) from the shell (1) and lay it flat. Place the sample container on the weighing part (11) and read and weigh the required mass of the recycled black powder sample through the display module (12).

7. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 4, characterized in that, The cuvette (5) has at least three through holes (13) communicating with the interior, and each through hole (13) is provided with a detachable rubber cap (14); the three through holes (13) serve as the test solution injection port, the air pressure balance port and the reagent replenishment port, respectively. The step of transferring the supernatant to a cuvette (5) after removing interfering ions through a purification device also includes: Open the rubber cap (14) at the air pressure balance port, inject the supernatant through the test liquid injection port, and tighten all the rubber caps (14) again after injection.

8. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 1, characterized in that, The housing (1) has an external protrusion (15) on one side, the external protrusion (15) has an opening at the top and extends to the bottom to form a placement groove (4); the external protrusion (15) has a grip handle (16) on the side away from the housing (1).

9. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 1, characterized in that, The fluoride ion colorimetric reagent contains an anti-interference component to eliminate the interference of metal ions in the colorimetric solution on the color development.

10. The method for detecting water-soluble fluoride ions in recycled black powder according to claim 6, characterized in that, The top of the housing (1) is also provided with a magnetic particle receiving groove (17), and a magnetic particle is pre-placed in the magnetic particle receiving groove (17); Before mixing the recycled black powder sample with a measured amount of water in a mixing container, the process further includes: Remove the magnetic particles from the magnetic particle receiving tank (17) and place them inside the mixing container.

Images