Device and method for determining content of iron filings in carbon-based new material

Abstract

The application relates to a device and method for measuring the content of iron filings in carbon-based new materials. A closed sample bin is used to place a sample to be measured. The closed sample bin is provided with a first inlet, a second inlet and an outlet. An inert gas storage tank is communicated with the first inlet. High-pressure inert gas injected into the closed sample bin is dispersed into aerosols under the action of airflow shearing. One end of a magnetic separation detection chamber is communicated with the outlet, and the other end is communicated with the second inlet. The aerosols flow circularly between the inert gas storage tank and the magnetic separation detection chamber. A magnetic capture medium is arranged in the magnetic separation detection chamber, and an electromagnet is arranged on the outer wall of the magnetic separation detection chamber to generate a magnetic field concentrated on the magnetic capture medium, so that the magnetic capture medium adsorbs and captures the iron filings in the aerosols. A laser-induced breakdown spectroscopy detection probe is arranged in the magnetic separation detection chamber to collect the intensity of the characteristic spectral line of the iron element on the surface of the magnetic capture medium. The sample dispersion, magnetic separation and online detection whole process automation is realized.

Description

Technical Field

[0001] This application relates to the field of carbon-based new material detection technology, and in particular to a device and method for determining the iron content in carbon-based new materials. Background Technology

[0002] Carbon-based new materials are key foundational materials for strategic emerging industries such as new energy, high-end manufacturing, and electronic information. Their purity, especially the content of metallic impurities, directly affects the performance, reliability, and safety of downstream products. Taking conductive carbon black, graphite, and carbon nanotubes used in lithium-ion batteries as examples, if these materials contain iron filings, their high conductivity and strong catalytic activity will catalyze the decomposition of the electrolyte during battery cycling, generating gas that damages the solid electrolyte interface film and triggers micro-short circuits. In severe cases, this can lead to battery thermal runaway, posing a significant safety hazard.

[0003] Currently, commonly used methods for iron content detection in this field mainly include: traditional acid digestion-atomic absorption spectrometry, inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometry, magnetic separation tube method, and optical microscopy or scanning electron microscopy. These methods have significant drawbacks in practical applications: the pretreatment process is complex and time-consuming, typically requiring several hours to days, failing to meet the rapid testing needs of production sites; most methods can only determine total iron content, unable to distinguish between elemental iron filings and non-hazardous iron forms such as iron oxide, iron salts, and ferroalloys, resulting in test results that do not accurately reflect safety risks; many are destructive tests, consuming strong acids and other reagents, generating waste liquid pollution, and samples cannot be recovered; detection sensitivity is low, human error is large, and online continuous monitoring is difficult to achieve. Therefore, developing a device and method capable of selectively, rapidly, non-destructively, and accurately determining the elemental iron filings content in new carbon-based materials is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0004] This application provides a device and method for determining the iron filings content in carbon-based new materials. By using dry aerosol dispersion, high-gradient magnetic field selective collection, and laser-induced breakdown spectroscopy for online quantification, it achieves efficient separation, enrichment, and accurate detection of elemental iron filings. It has the advantages of high selectivity, fast speed, non-destructive and environmentally friendly operation, high sensitivity, and high degree of automation, and can simultaneously meet the needs of accurate laboratory testing and online monitoring on production lines.

[0005] On the one hand, this application provides a device for determining the iron filings content in a novel carbon-based material, comprising: A sealed sample chamber is used to hold the sample to be tested. The sealed sample chamber has a first inlet, a second inlet, and an outlet. An inert gas storage tank is connected to the first inlet and is used to inject high-pressure inert gas into a sealed sample chamber, so that the sample to be tested in the sealed sample chamber is dispersed into an aerosol under the shearing action of the airflow. The magnetic separation detection chamber has one end connected to the outlet via a pipeline and the other end connected to the second inlet via a pipeline. A circulating fan is installed on the pipeline to allow the aerosol to circulate between the inert gas storage tank and the magnetic separation detection chamber. Magnetic trapping medium is placed in the magnetic separation detection chamber and is used to capture iron filings in aerosols. A laser-induced breakdown spectroscopy detection probe is set up in a magnetic separation detection chamber to collect the intensity of characteristic spectral lines of iron on the surface of a magnetic trapping medium. An electromagnet is installed on the outer wall of the magnetic separation detection chamber to generate a magnetic field concentrated on the magnetic trapping medium, causing the magnetic trapping medium to adsorb and capture iron filings in the aerosol.

[0006] In one possible design, the magnetic trapping medium has a porous structure with an internally interconnected three-dimensional network of channels, a porosity of 70%-95%, and a pore size distribution of 10-500 μm.

[0007] In one possible design, the surface of the magnetic trapping medium is formed with micron-scale textures or fibrous protrusions.

[0008] In one possible design, the magnetic trapping medium is selected from one or more combinations of stainless steel fiber felt, nickel foil porous material, magnetic microsphere sintered body, iron-nickel alloy foam, and polymer porous material with a magnetically coated surface.

[0009] In one possible design, the magnetic trapping medium is detachably installed on the inner wall of the magnetic separation detection chamber, with the outer periphery of the magnetic trapping medium abutting against the inner wall of the magnetic separation detection chamber.

[0010] In one possible design, the laser-induced breakdown spectroscopy detection probe is equipped with a detection channel for Fe element at a wavelength of 259.94 nm.

[0011] In one possible design, a dispersion nozzle is installed at the first inlet; valves are respectively installed at the first inlet, the second inlet, and the outlet.

[0012] In one possible design, both the first and second inlets are located at the bottom of the sealed sample chamber.

[0013] In one possible design, the magnetic field strength of the electromagnet is 0-2.5T.

[0014] On the other hand, this application also provides a method for determining the iron content in a carbon-based new material, based on the above-mentioned apparatus for determining the iron content in a carbon-based new material, the method comprising: The sample to be tested is placed in a sealed sample chamber, and high-pressure inert gas is introduced to disperse the sample into an aerosol and circulate it. Turn on the electromagnet to allow the aerosol to pass through the magnetic separation and detection chamber, and adsorb the elemental iron filings onto the magnetic collection medium; A laser-induced breakdown spectroscopy probe was used to acquire characteristic spectral line signals of iron in real time and plot enrichment curves. When the iron filings collection reaches saturation, the system stops separating and calculates the iron filings content based on the spectral line intensity.

[0015] The beneficial effects of this application are as follows: The device for determining the iron content in carbon-based new materials disclosed in this application utilizes the characteristic that a high-gradient magnetic field only has ferromagnetic adsorption for elemental iron, which can accurately capture elemental iron filings and completely eliminate interference from non-magnetic and low-magnetic iron forms such as iron oxide, iron salts, iron silicates, and iron alloys. It only measures iron filings that may harm batteries and does not consider harmless iron forms. The test results are more in line with the actual risks of downstream applications and solve the industry pain point that traditional methods can only measure total iron and cannot distinguish the forms.

[0016] The fully dry integrated process eliminates the need for complex pretreatments such as sample digestion, volume adjustment, and reagent preparation. The detection cycle for a single sample is only 5-15 minutes, which is dozens of times more efficient than the detection time of traditional methods, which can take several hours to several days. It can realize real-time, rapid, and continuous monitoring on the production line.

[0017] The testing process does not use any chemical reagents such as strong acids, strong alkalis, or organic solvents, and does not damage the structure and properties of carbon-based materials. Samples can be completely recovered after testing. It produces no waste liquid, waste gas, or waste residue, eliminating the environmental pollution and safety risks associated with traditional wet digestion at the source.

[0018] Through the high specific surface area and deep enrichment effect of the three-dimensional porous magnetic trapping medium, it can capture ultrafine iron filings from nanometer to micrometer scale, with a detection limit as low as 0.1 ppm, which can meet the stringent control requirements for trace metal impurities in high-end lithium battery materials, semiconductor carbon materials, etc.

[0019] It adopts a closed-loop circulation structure to avoid dust leakage and external pollution. Parameters such as magnetic field strength, airflow rate, and detection frequency are adjustable, which can adapt to the detection needs of different materials, concentrations, and particle sizes. It is stable and reliable in long-term operation and meets the requirements for continuous use in industrial sites.

[0020] The method for determining the iron filings content in carbon-based new materials provided in this application achieves fully intelligent operation of the entire process, including automatic dispersion, automatic circulation, automatic collection, automatic detection, automatic saturation determination, and automatic result calculation. This significantly reduces human error, and the method offers good repeatability and high accuracy. Data can be stored, uploaded, and exported in real time, meeting the needs of laboratory standardization, factory digitalization, and quality traceability management. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the device for determining the iron content in carbon-based new materials provided in the embodiments of this application; Figure label: 1. Sealed sample chamber; 11. First inlet; 12. Second inlet; 13. Outlet; 2. Inert gas storage tank; 3. Magnetic separation detection chamber; 4. Circulating fan; 5. Magnetic trapping medium; 6. Electromagnet; 7. Laser-induced breakdown spectroscopy detection probe. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. 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.

[0024] The following is combined with Figure 1 This application describes the device for determining the iron content in a carbon-based novel material provided in its embodiments.

[0025] The device includes a sealed sample chamber 1, an inert gas storage tank 2, a magnetic separation and detection chamber 3, a magnetic trapping medium 5, and a laser-induced breakdown spectroscopy detection probe 7.

[0026] The sealed sample chamber 1 is used to hold the sample to be tested. The sealed sample chamber 1 has a first inlet 11, a second inlet 12, and an outlet 13. The first inlet 11 and the second inlet 12 are both located at the bottom of the sealed sample chamber 1, and the outlet 13 is located at the top of the sealed sample chamber 1. Bottom-entry airflow creates a bottom-up fluidized dispersion, preventing sample accumulation and dead zones, resulting in more thorough dispersion and smoother circulation, thus improving the representativeness and consistency of the test. The first inlet 11 is equipped with a dispersion nozzle, which generates a high-pressure shear airflow, making the sample more evenly dispersed and preventing agglomeration. Valves are installed at the first inlet 11, the second inlet 12, and the outlet 13, respectively. These valves can precisely control the airflow and flow rate, facilitating system sealing, debugging, maintenance, and safe operation.

[0027] The inert gas storage tank 2 is connected to the dispersion nozzle at the first inlet 11 via a pipeline. The dispersion nozzle is used to inject high-pressure inert gas into the sealed sample chamber 1, so that the sample to be tested in the sealed sample chamber 1 is dispersed into aerosol under the shearing action of the airflow.

[0028] One end of the magnetic separation detection chamber 3 is connected to the outlet 13 through a pipeline, and the other end is connected to the second inlet 12 through a pipeline. A circulating fan 4 is installed on the pipeline to make the aerosol circulate between the inert gas storage tank 2 and the magnetic separation detection chamber 3.

[0029] The magnetic trapping medium 5 is placed in the magnetic separation and detection chamber 3. The magnetic trapping medium 5 can be cylindrical, disc-shaped, or cylindrical, with a diameter matching the inner diameter of the magnetic separation and detection chamber 3 and a thickness of 2-10 mm. The magnetic trapping medium 5 is used to capture iron filings in the aerosol.

[0030] Electromagnet 6 is installed on the outer wall of the magnetic separation detection chamber 3. The magnetic field strength of electromagnet 6 is adjustable from 0 to 2.5T. The magnetic field strength is adjustable over a wide range, which can adapt to the capture requirements of iron filings of different particle sizes and contents. The attraction force is controllable and the separation selectivity is high. It can capture trace amounts of iron filings without causing the medium to overheat or the adsorption to overload due to excessive magnetic field strength.

[0031] By adjusting the magnetic field strength of electromagnet 6 to a preset value, a high-gradient strong magnetic field can be formed within the magnetic separation detection chamber 3, generating a magnetic field concentrated at the magnetic trapping medium 5, thus fully magnetizing the magnetic trapping medium 5. When the aerosol circulates through the magnetic trapping medium 5, the elemental iron filings are efficiently adsorbed, fixed, and enriched in the magnetic trapping medium 5 under the action of magnetic force and inertial interception. Non-magnetic carbon-based materials pass smoothly with the airflow and return to the sample chamber for continued circulation, achieving efficient and rapid separation of elemental iron filings from the matrix.

[0032] The laser-induced breakdown spectroscopy (LASPS) probe 7 is installed on the inner wall of the magnetic separation detection chamber 3. The LASPS probe 7 is equipped with a detection channel for Fe element at a wavelength of 259.94 nm. The LASPS probe 7 is automatically triggered at preset time intervals, and the laser precisely irradiates the surface of the magnetic trapping medium 5 to collect the characteristic spectrum of iron element. The system captures the intensity of the characteristic spectral line of iron element at a wavelength of 259.94 nm in real time, dynamically generating and displaying the iron filings enrichment curve, intuitively reflecting the enrichment rate and accumulation amount of iron filings.

[0033] Utilizing the aforementioned technical solution, an integrated structure comprising a sealed chamber, gas dispersion, closed-loop circulation, magnetic collection, magnetic field supply, and laser detection achieves fully automated sample dispersion, magnetic separation, and online detection. This eliminates the need for chemical digestion, resulting in rapid, non-destructive, and environmentally friendly detection. The closed-loop circulation enhances the adequacy of iron filings collection, ensuring detection accuracy and repeatability.

[0034] In some specific embodiments, the magnetic trapping medium 5 has a porous structure with an internally interconnected three-dimensional network of pores. The porosity is 70%-95%, and the pore size distribution is 10-500 μm. The three-dimensional interconnected pores and high porosity ensure smooth airflow and low pressure drop, while providing a huge adsorption surface area. This allows for the efficient capture of iron filings from nanometer to micrometer scale, significantly improving enrichment efficiency and detection sensitivity, and meeting the needs of trace impurity detection.

[0035] In some specific embodiments, the surface of the magnetic trapping medium 5 is formed with micron-level uneven textures or fibrous protrusions. On the one hand, this can further increase the specific surface area, and on the other hand, it can form physical hooking sites, thereby significantly enhancing the ability to capture ultrafine iron filings, preventing the iron filings from being washed away by the airflow, improving the trapping stability, and increasing the detection accuracy.

[0036] Specifically, the magnetic collecting medium 5 is detachably installed on the inner wall of the magnetic separation detection chamber 3, with its outer periphery abutting against the inner wall of the chamber 3. This detachable structure facilitates quick replacement, cleaning, and calibration. The sealed outer periphery forces all aerosols through the filter medium, preventing short-circuit flow and missed detections, ensuring complete iron filings collection, and improving quantitative accuracy.

[0037] The magnetic trapping medium 5 is selected from one or more combinations of stainless steel fiber felt, nickel foil porous material, magnetic microsphere sintered body, iron-nickel alloy foam, and polymer porous material with magnetic coating on the surface, so as to be suitable for different working conditions and sample systems.

[0038] This application also provides a method for determining the iron content in a carbon-based new material. Based on the above-mentioned device for determining the iron content in a carbon-based new material, the method specifically includes: Accurately weigh a certain amount of carbon-based new material sample to be tested, and place it evenly into the sealed sample chamber 1. Close and lock the chamber door, and check the overall airtightness of the sealed sample chamber 1, pipeline, and magnetic separation detection chamber 3 to ensure that the system operates in a completely sealed state to prevent aerosol leakage, external dust interference, or sample oxidation.

[0039] Open the inert gas storage tank 2 and adjust the gas pressure so that the high-pressure inert gas is injected from the bottom of the sealed sample chamber 1 through the dispersion nozzle. Under the impact, shearing and fluidization of the high-speed airflow, the agglomerated carbon-based powder sample is fully dispersed to form a stable and uniform aerosol system, which prevents the iron filings from being wrapped by the carbon-based particles and ensures that the iron filings are fully exposed and captured.

[0040] Start the circulating fan 4 and adjust it to the preset flow rate to form a stable closed-loop circulation of aerosol between the sealed sample chamber 1, the outlet pipeline, the magnetic separation detection chamber 3, and the return pipeline; through continuous circulation, the sample particles are evenly dispersed and pass through the magnetic collection medium 5 multiple times, thereby improving the iron filings collection efficiency and the accuracy of the detection results.

[0041] Turn on the electromagnet 6 and adjust the magnetic field strength to the preset value to form a high gradient strong magnetic field in the magnetic separation detection chamber 3, so that the magnetic trapping medium 5 is fully magnetized. When the aerosol circulates through the porous medium, the elemental iron filings are efficiently adsorbed, fixed and enriched on the surface of the medium and in the three-dimensional pores under the action of magnetic force and inertial interception. The non-magnetic carbon-based materials pass smoothly with the airflow and return to the sample chamber to continue the circulation, so as to achieve efficient and rapid separation of elemental iron filings from the matrix.

[0042] The laser-induced breakdown spectroscopy detection probe 7 is automatically triggered at a preset time interval. The laser precisely irradiates the surface of the magnetic trapping medium 5 and collects the characteristic spectrum of iron. The system captures the intensity of the characteristic spectral line of iron at a wavelength of 259.94nm in real time and dynamically generates an iron filings enrichment curve, which intuitively reflects the enrichment rate and accumulation amount of iron filings.

[0043] The control system calculates the growth rate of the spectral signal in real time. When the signal growth rate detected multiple times is lower than the set threshold, it is determined that the magnetic collecting medium 5 has reached saturation in adsorbing the iron filings and the iron filings have been completely collected. The system automatically shuts down the circulating fan 4, the inert gas, and the electromagnet 6 in sequence, terminating the separation and circulation process.

[0044] The system automatically reads the average value of multiple spectral signal intensities during the saturation stage, combines it with the pre-established standard working curve of iron filings content-spectral intensity, automatically calculates the mass fraction or absolute mass value of iron filings in the sample to be tested, and directly displays, stores and outputs the test results to complete the entire measurement process.

[0045] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0048] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0049] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A device for determining the iron filings content in a novel carbon-based material, characterized in that, include: A sealed sample chamber, wherein the sealed sample chamber is used to place the sample to be tested, and the sealed sample chamber has a first inlet, a second inlet and an outlet; An inert gas storage tank, which is connected to the first inlet, is used to inject high-pressure inert gas into the sealed sample chamber, so that the sample to be tested in the sealed sample chamber is dispersed into aerosol under the shearing action of the airflow. A magnetic separation detection chamber, one end of which is connected to the outlet via a pipeline, and the other end of which is connected to the second inlet via a pipeline. A circulating fan is installed on the pipeline to allow the aerosol to circulate between the inert gas storage tank and the magnetic separation detection chamber. A magnetic trapping medium is disposed in the magnetic separation detection chamber and is used to capture iron filings in aerosols. An electromagnet is disposed on the outer wall of the magnetic separation detection chamber to generate a magnetic field concentrated at the magnetic trapping medium, so that the magnetic trapping medium adsorbs and captures iron filings in the aerosol. A laser-induced breakdown spectroscopy detection probe is installed in the magnetic separation detection chamber to collect the intensity of the characteristic spectral lines of iron on the surface of the magnetic trapping medium.

2. The device for determining the iron content in carbon-based new materials according to claim 1, characterized in that, The magnetic trapping medium has a porous structure with an internally interconnected three-dimensional network of pores. The porosity is 70%-95% and the pore size distribution is 10-500μm.

3. The device for determining the iron content in carbon-based new materials according to claim 2, characterized in that, The surface of the magnetic trapping medium is formed with micron-level uneven textures or fibrous protrusions.

4. The device for determining the iron content in carbon-based new materials according to claim 3, characterized in that, The magnetic trapping medium is selected from one or more combinations of stainless steel fiber felt, nickel foil porous material, magnetic microsphere sintered body, iron-nickel alloy foam, and polymer porous material with magnetic coating on the surface.

5. The apparatus for determining the iron content in carbon-based new materials according to any one of claims 1-4, characterized in that, The magnetic trapping medium is detachably installed on the inner wall of the magnetic separation detection chamber, and the outer periphery of the magnetic trapping medium abuts against the inner wall of the magnetic separation detection chamber.

6. The apparatus for determining the iron content in carbon-based new materials according to claim 1, characterized in that, The laser-induced breakdown spectroscopy detection probe is equipped with a detection channel for Fe element with a wavelength of 259.94 nm.

7. The apparatus for determining the iron content in carbon-based new materials according to claim 1, characterized in that, The first inlet is equipped with a dispersion nozzle; valves are respectively provided at the first inlet, the second inlet, and the outlet.

8. The apparatus for determining the iron content in carbon-based new materials according to claim 1, characterized in that, Both the first inlet and the second inlet are located at the bottom of the sealed sample chamber.

9. The apparatus for determining the iron content in carbon-based new materials according to claim 1, characterized in that, The magnetic field strength of the electromagnet is 0-2.5T.

10. A method for determining the iron filings content in a novel carbon-based material, characterized in that, Based on the apparatus for determining the iron content in carbon-based new materials according to any one of claims 1-9, the method includes: The sample to be tested is placed in a sealed sample chamber, and high-pressure inert gas is introduced to disperse the sample into an aerosol and circulate it. Turn on the electromagnet to allow the aerosol to pass through the magnetic separation and detection chamber, and adsorb the elemental iron filings onto the magnetic collection medium; A laser-induced breakdown spectroscopy probe was used to acquire characteristic spectral line signals of iron in real time and plot enrichment curves. When the iron filings collection reaches saturation, the system stops separating and calculates the iron filings content based on the spectral line intensity.

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