Method for removing iron from powder

Abstract

This invention provides a method for iron removal experiments using powder, comprising: obtaining an iron separator test platform; obtaining multiple sets of test materials, wherein each set of test materials includes powder and metal, and the metal in different sets of test materials is different; spraying each set of test materials from different heights under a first magnetic field strength into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the first magnetic field strength; adjusting the magnetic field strength of the iron separator test platform to a second magnetic field strength, and spraying each set of test materials from different heights into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the second magnetic field strength; and obtaining a table of the interception rates of each set of test materials at different magnetic field strengths and different heights. The technical solution of this application effectively solves the problem in related technologies where setting iron removal parameters based on experience leads to poor iron removal performance of the iron separator.

Description

Technical Field

[0001] This invention relates to the field of iron removal technology, and more specifically, to an experimental method for removing iron from powder materials. Background Technology

[0002] During the production and transportation of powdered ingredients, they need to pass through pipelines, which are generally made of metal. During transportation, metal fragments from the side walls of these pipelines can easily detach and become mixed into the powder. For milk powder products, ensuring food safety and protecting public health and lives is a principle that all food industry practitioners must always adhere to. Relevant regulations explicitly prohibit the production and sale of food containing foreign matter. Foreign matter is a typical physical hazard in the Hazard Analysis Critical Control Point (HACCP) system, especially metallic foreign matter, which can seriously threaten life safety and must be effectively controlled in food production and processing. To reduce foreign matter, effective measures such as using sieves, traps, magnets, and metal detectors should be adopted to reduce the risk of metal or other foreign matter contamination in food.

[0003] In related technologies, iron removal is achieved using a magnetic separator. However, the iron removal efficiency is affected by factors such as the distance between the powder outlet and the magnetic field strength of the separator. Currently, the distance and magnetic field strength are typically set based on experience, which can negatively impact the iron removal efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide an experimental method for removing iron from powder materials, thereby solving the problem in related technologies where iron removal parameters are set based on experience, resulting in poor iron removal performance of the iron remover.

[0005] To achieve the above objectives, the present invention provides an experimental method for removing iron from powder, comprising: obtaining an iron separator test platform; obtaining multiple sets of test materials, wherein each set of test materials includes powder and metal, and the metal in different sets of test materials is different; spraying each set of test materials from different heights under a first magnetic field strength into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the first magnetic field strength; adjusting the magnetic field strength of the iron separator test platform to a second magnetic field strength, and spraying each set of test materials from different heights into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the second magnetic field strength; and obtaining a table of the interception rates of each set of test materials at different magnetic field strengths and different heights.

[0006] Further, the steps for obtaining the iron separator test platform include: obtaining the iron separator test platform to be tested; pouring the powder into the iron separator test platform to be tested and detecting the pass rate of the iron separator test platform; if the pass rate is greater than or equal to 90%, the iron separator test platform to be tested is used as the iron separator test platform.

[0007] Furthermore, the steps between obtaining multiple sets of test materials, each set including powder and metal, with different metals in different sets of test materials, and the step of sprinkling each set of test materials from different heights under a first magnetic field strength into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the first magnetic field strength, include: performing finite element analysis on the magnetic rod of the iron separator to obtain the position of maximum magnetic field strength; setting the position of maximum magnetic field strength of the magnetic rod at the center of the iron separator test platform; and aligning the test material with the center of the iron separator test platform.

[0008] Furthermore, if the pass rate is greater than or equal to 90%, the step of using the iron separator test platform as the iron separator test platform includes: sprinkling the test material into the iron separator test platform from a fixed height to obtain a first interception rate; changing the spacing of the magnetic rods of the iron separator test platform, and sprinkling the test material into the iron separator test platform from a fixed height again to obtain another first interception rate; and determining the minimum spacing of the magnetic rods based on the multiple first interception rates.

[0009] Further, the steps of pouring the powder into the iron separator test platform and testing the pass rate of the iron separator test platform include: loading the powder into a container with a smooth inner wall; covering the opening of the container with a baffle; flipping the container so that the baffle is at the bottom and shaking the container; placing the baffle and the container on the iron separator test platform; removing the baffle and observing the flow state of the powder.

[0010] Furthermore, the step of spraying each group of test materials from different heights into the iron separator test platform under the first magnetic field strength to obtain the interception rate of each group of test materials at different heights under the first magnetic field strength includes: removing the magnetic rod from the iron separator test platform; brushing off and collecting the powder adsorbed on the magnetic rod; rinsing and drying the collected powder; and weighing the dried metal and comparing it with the initial metal.

[0011] Furthermore, the step of sprinkling each group of test objects from different heights into the iron separator test platform under the first magnetic field strength to obtain the interception rate of each group of test objects at different heights under the first magnetic field strength includes: sprinkling the test objects from the initial height position into the iron separator test platform to obtain the interception rate of each group of test objects at the initial height; measuring again by increasing the test objects by a preset distance each time based on the initial height; wherein the preset distance is between 100mm and 300mm.

[0012] Further, the step of adjusting the magnetic field strength of the iron separator test platform to a second magnetic field strength, and sprinkling each group of test materials into the iron separator test platform from different heights to obtain the interception rate of each group of test materials at different heights under the second magnetic field strength includes: sprinkling the test materials into the iron separator test platform from a fixed height to obtain the interception rate of each group of test materials under the initial magnetic field strength; increasing or decreasing the magnetic field strength of the iron separator test platform by a preset value, and then measuring again; wherein the preset value is between 1000GS and 3000GS.

[0013] Furthermore, the steps for multiple test samples include: preparing cast iron chips, 304 austenitic stainless steel chips, and 316 austenitic stainless steel chips.

[0014] Furthermore, the cast iron chips are set to an ellipsoidal shape, and the 304 austenitic stainless steel chips and 316 austenitic stainless steel chips are both set to a flat sheet shape. The size of the cast iron chips is limited to 0.1mm×0.1mm×0.1mm to 0.3mm×0.3mm×0.3mm, and the size of the 304 austenitic stainless steel chips and 316 austenitic stainless steel chips is between 0.05mm×0.1mm×0.3mm and 0.2mm×0.3mm×0.5mm.

[0015] Applying the technical solution of this invention, a magnetic separator test platform and multiple sets of test samples are first obtained to prepare for subsequent experiments. To better simulate the types of metal debris encountered in actual production, different metal debris is mixed into the powder to obtain multiple sets of test samples, with the different metal debris representing the types encountered in actual production. Next, an iron removal experiment is conducted. First, one type of test sample is sprinkled into the magnetic separator test platform from multiple different heights, ensuring that the magnetic field strength of the test platform is the same, i.e., all are at the first magnetic field strength. Then, the remaining test samples are sprinkled into the magnetic separator test platform from different heights, thus obtaining the interception rate of each test sample at different heights under the same magnetic field strength. Next, the magnetic field strength is adjusted to a second magnetic field strength, and each test sample is sprinkled into the magnetic separator test platform from different heights, thus obtaining the interception rate of each test sample at different heights under the second magnetic field strength. Finally, the interception rates of each test sample at different magnetic field strengths and different heights are statistically analyzed in a table to obtain an interception rate table. Through the above operational steps, an interception rate table can be obtained. This table serves as a guide; in actual production, simply consulting the interception rate table will reveal the parameters for optimal iron removal efficiency, namely, the magnetic field strength and the height between the discharge port and the iron separator test platform. Setting these parameters according to the interception rate table will improve the iron removal effect. Therefore, the technical solution of this application effectively solves the problem in related technologies where setting iron removal parameters based on experience leads to poor iron removal efficiency. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0017] Figure 1 A schematic diagram of the overall process of an embodiment of the experimental method for removing iron from powder according to the present invention is shown;

[0018] Figure 2 It shows Figure 1 A schematic diagram of the specific process of step S10 in the experimental method for removing iron from powder materials;

[0019] Figure 3 It shows Figure 2 A detailed flowchart of step S12;

[0020] Figure 4 It shows Figure 2 A detailed flowchart of step S13;

[0021] Figure 5It shows Figure 1 A schematic diagram of the specific process of step S30 in the experimental method for removing iron from powder materials;

[0022] Figure 6 It shows Figure 1 A flowchart illustrating the process between steps S20 and S30 of the experimental method for removing iron from powder.

[0023] Figure 7 It shows Figure 1 The effect of the drop height on the interception rate of the iron removal test method for powder materials;

[0024] Figure 8 It shows Figure 1 The effect of metal type on the interception rate in the experimental method of iron removal from powder;

[0025] Figure 9 It shows Figure 1 The effect of magnetic field strength on the interception rate of the iron removal experiment method for powder materials;

[0026] Figure 10 It shows Figure 1 The effect of the net distance between magnetic rods on the interception rate in the experimental method of iron removal from powder. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0030] Magnetic separators, as permanent magnet devices, can remove ferromagnetic metallic foreign objects from non-magnetic materials. In recent years, they have been widely used in the deep processing of food, such as sugar refining, grain storage, and solid beverages, especially in the infant formula industry. Almost all milk powder processing companies install magnetic separators, with box-type grid separators being particularly prevalent. However, the effective interception rate of metallic foreign objects is affected by various factors during use; without a reasonable design, it is difficult to achieve the expected interception effect. To improve interception efficiency, such as... Figure 1 As shown, in this embodiment, the iron removal experiment method for powder includes:

[0031] Step S10: Obtain the iron separator test platform; Step S20: Obtain multiple sets of test materials, each set of test materials includes powder and metal, and the metal in different sets of test materials is different; Step S30: Sprinkle each set of test materials from different heights under the first magnetic field strength into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the first magnetic field strength; Step S40: Adjust the magnetic field strength of the iron separator test platform to the second magnetic field strength, and sprinkle each set of test materials from different heights into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the second magnetic field strength; Step S50: Obtain a table of interception rates of each set of test materials at different magnetic field strengths and different heights.

[0032] Applying the technical solution of this embodiment, a magnetic separator test platform and multiple sets of test materials are first obtained to prepare for subsequent experiments. To better simulate the types of metal debris encountered in actual production, different metal debris is mixed into the powder to obtain multiple sets of test materials. These different metal debris are the same types encountered in actual production. Next, an iron removal experiment is conducted. First, one type of test material is sprinkled into the magnetic separator test platform from multiple different heights, ensuring that the magnetic field strength of the test platform is the same, i.e., all are at the first magnetic field strength. Then, the remaining test materials are sprinkled into the magnetic separator test platform from different heights, thus obtaining the interception rate of each test material at different heights under the same magnetic field strength. Next, the magnetic field strength is adjusted to a second magnetic field strength, and each test material is sprinkled into the magnetic separator test platform from different heights again, thus obtaining the interception rate of each test material at different heights under the second magnetic field strength. Finally, the interception rate of each test object at different magnetic field strengths and heights is statistically analyzed and recorded in a table to obtain an interception rate table. Through the above steps, an interception rate table can be obtained, which serves as a guide. In actual production, simply consulting the interception rate table will reveal the parameters for optimal iron removal efficiency, namely the magnetic field strength and the height between the discharge port and the iron separator test platform. Setting these parameters according to the interception rate table will improve the iron removal effect. Therefore, the technical solution of this embodiment effectively solves the problem in related technologies where setting iron removal parameters based on experience leads to poor iron removal efficiency.

[0033] In this embodiment, a six-layer adjustable box-type grid separator is used. The upper flange connects to material pipelines of different lengths, and the lower end connects to a material collection bag. The magnetic rod has a diameter of 25mm. During the test, milk powder mixed with metal simulating test material is poured into the material pipeline opening, and the collection bag collects the material passing through the magnetic rod.

[0034] The technical solution of the embodiment is based on the conclusion of single-factor experiments, and a comprehensive matrix analysis is performed on different design schemes to obtain an interception rate table.

[0035] Currently, only the "Detailed Rules for the Examination of Production Licenses for Infant Formula Milk Powder (2013 Edition)" explicitly stipulates that infant formula milk powder companies should effectively control metal objects with a diameter of not less than 2 mm. However, in actual industrial production, metal foreign objects are often the size of the simulated test object selected in this study, with a volume only one-thousandth of that specified in the national standard. Due to differences in production processes and quality control levels within the industry, there are currently no clear regulatory standards for the effective interception rate of such small metal foreign objects.

[0036] Based on visually acceptable levels and historical consumer feedback data, assuming the minimum acceptable standard is an effective interception rate of ≥80% for cast iron, 304 stainless steel, and 316 stainless steel, with a net distance of 25mm (to avoid bridging and material blockage), a matrix analysis is performed using a minimum acceptable magnetic ring field strength of 10000GS and a reasonable manufacturing upper limit of 14000GS for the equipment. The critical conditions are: when the magnetic ring field strength is 10000GS, the material drop height is ≤100mm, and the number of magnetic ring layers is ≥6. When the magnetic ring field strength is 14000GS, if the drop height is ≤100mm, the number of magnetic ring layers is ≥4; if 100m < material drop height ≤300mm, the number of magnetic ring layers is ≥6.

[0037] The specific interception rate table is as follows:

[0038]

[0039] Specifically, in this embodiment, the equipment used is as follows: box-type grid iron separator: GHS, Demag Electromechanical Technology (Shanghai) Co., Ltd.; gaussmeter: 6010, SYPRIS Corporation, USA; industrial microscope: ZQ-616, Shanghai Zhiqi Industrial Co., Ltd.; precision balance: ME type, Mettler Toledo Technologies, USA; constant temperature oven: HPG-280B, Harbin Donglian Electronic Technology Development Co., Ltd.; glass desiccator: 350, Chengdu Dianrui Experimental Instrument Co., Ltd.

[0040] It should be noted that the powder mentioned above refers to milk powder, but it can also be protein raw materials, powdered oils, starch, food additives, etc.

[0041] In the experiment investigating the effect of different heights on the interception rate, 0.02 kg of cast iron metal simulation test material was thoroughly mixed with 9.98 kg of milk powder. Material pipelines with heights of 100 mm, 300 mm, 500 mm, and 700 mm were installed. Six layers of magnetic rods were used uniformly, with a net distance between the magnetic rods (Note: net distance = center distance - magnetic rod diameter) of 30 mm and a strong magnetic field strength of 14000 GS. Milk powder mixed with metal simulation test material was poured into the material pipeline opening at a uniform speed, and the interception rate of each layer of the iron separator was recorded.

[0042] Grid separators have a good effect on intercepting metallic foreign objects. Research by the Canadian Food Safety Knowledge Centre also shows that bar-shaped magnetic rods can be widely used to remove small amounts of metallic contaminants from flowing powders, particles, fibers, and liquids. Figure 7As shown, the interception rate gradually decreases with increasing material falling height. There is no significant difference between 100mm and 300mm, but the interception rate begins to decline from 500mm. This is because milk powder and metal foreign objects accelerate continuously under the influence of gravity, increasing their kinetic energy. When some particles fall at relatively weak positions in the magnetic field between the magnetic rods, they are not sufficiently captured by the magnetic attraction and will escape. Since the magnetic rods in each layer of the grid separator are arranged in a cross pattern, the weakest position of the magnetic field in the upper layer is exactly the strongest position of the magnetic field in the lower layer. At the same time, they will be subjected to tangential attraction when passing through the magnetic field, and their kinetic energy will decrease. Particles escaping from the upper layer have a certain probability of being intercepted by the magnetic rods in the lower layer. Therefore, at a falling height of 500mm, the interception rate of layers 1-2 is 97.5%, the interception rate of layers 3-4 is 1.0%, and the interception rate of layers 5-6 is 0.5%. Finally, the overall interception rate of layers 1-6 is not significantly different from that of 100mm and 300mm. However, when the falling height reaches 700mm, the interception rate decreases significantly due to the increased kinetic energy of the particles and the resulting greater escape. Experiments show that the interception rate gradually decreases with increasing falling height, and the decrease is particularly pronounced when the falling height is ≥700mm.

[0043] In the experiment investigating the effect of different types of test materials on the interception rate, 0.02 kg of cast iron, 304 stainless steel, and 316 stainless steel metal simulation test materials were thoroughly mixed with 9.98 kg of milk powder. A material pipeline with a height of 500 mm was installed, and 6 layers of magnetic rods were used uniformly with a net distance of 30 mm between the magnetic rods and a magnetic field strength of 14000 GS. The milk powder mixed with the metal simulation test materials was poured into the material pipeline opening at a uniform speed, and the interception rate of each layer of the iron separator was recorded.

[0044] According to relevant research, due to the non-equilibrium solidification process, cutting, and possible improper heat treatment during the melting of 304 and 316 austenitic stainless steel, a small amount of ferromagnetic ferrite and martensite phases may remain or form in the austenitic stainless steel. Furthermore, the use of magnetic clamps and direct current during assembly and welding operations can cause residual magnetism due to prolonged contact between the pipe and the wire connected to the DC power supply. The metal simulants used in this experiment were selected weld debris from the pipe and friction debris from the screw conveyor against the pipe wall, possessing a certain degree of adsorption capacity. Figure 8As shown, different metal types have a significant impact on the interception rate of 1-2 layers. Cast iron particles can be almost completely captured, while the interception rates of 304 and 316 stainless steel particles are only 57.0% and 39.7%, respectively. However, as the number of interception layers in the magnetic separator increases, the difference in interception rate is significantly reduced. With 1-6 layers, the interception rates of 304 and 316 stainless steel particles increase to 85.5% and 76.9%, respectively. The experiment shows that different metal types have a significant impact on the interception rate. 304 and 316 stainless steel particles are more difficult to adsorb than cast iron particles, and increasing the number of interception layers in the magnetic separator is a very effective way to improve the interception rate.

[0045] In the experiment investigating the effect of magnetic field strength on the interception rate, 0.02 kg of cast iron metal simulation test material was thoroughly mixed with 9.98 kg of milk powder. A material pipeline with a height of 500 mm was installed, and 6 layers of magnetic rods were used with a net spacing of 30 mm. The magnetic rods were replaced with strong magnetic rings with field strengths of 8000 GS, 10000 GS, 12000 GS, and 14000 GS, respectively. The milk powder mixed with the metal simulation test material was poured into the material pipeline opening at a uniform speed, and the interception rate of each layer of the iron separator was recorded.

[0046] like Figure 9 As shown, the interception rate increases significantly with the increase of the magnetic field strength of the magnetic rod and the strong magnetic ring. For layers 1-2, the interception rates for 10000GS, 12000GS, and 14000GS are 93.5%, 96.8%, and 97.5%, respectively, all reaching relatively ideal levels. However, the interception rate for 8000GS is only 92.7% for layers 1-6. This is mainly because the tangential adsorption force of the magnetic field on the metal particles is relatively small. Although the grid separator uses a cross-arrangement, the velocity loss is small, and the entrainment effect of milk powder particles on metal particles becomes prominent, increasing the escape rate. Ciosk K et al. obtained the same conclusion when calculating the magnetic field and force in the 3D space of a magnetic separator for removing fine minerals based on the network magnetoresistance method. Experiments show that the field strength has a very significant impact on the interception rate; the stronger the field strength, the higher the interception rate.

[0047] In the experiment investigating the effect of magnetic rod clearance on the interception rate, 0.02 kg of cast iron metal simulating test material was thoroughly mixed with 9.98 kg of milk powder. A material pipeline with a height of 500 mm was installed. Six layers of magnetic rods were used uniformly, with a strong magnetic ring field strength of 14000 GS. The magnetic rod clearance was changed to 20 mm, 25 mm, 30 mm, and 35 mm respectively. The milk powder mixed with the metal simulating test material was poured into the material pipeline opening at a uniform speed. The interception rate of each layer of the iron separator was recorded. A bridging test was also conducted on each group (bridging test: test the powder passing rate).

[0048] like Figure 10As shown, the interception rate decreases significantly with increasing magnetic rod clearance. There is no significant difference between clearances of 20mm and 25mm, so increasing the number of interception layers has little effect. With a clearance of 30mm, the interception rate is 97.5% with 1-2 layers, slightly different from 25mm, but still within an acceptable range. With a clearance of 35mm, the interception rate is only 93.5% with 1-2 layers, a significant decrease. This is mainly due to the increased clearance between magnetic rods, which enlarges the weak magnetic field area and reduces the tangential attraction of the magnetic field to metal particles, thus lowering the interception rate. However, this problem is significantly improved with increasing the number of interception layers; with a clearance of 35mm, the interception rate increases to 97.2% with 1-6 layers.

[0049] However, excessively small net spacing may lead to bridging and blockage. Studies have shown that various interparticle cohesive forces exist in the powder, and the energy of interparticle interaction depends on factors such as glass transition, moisture content, particle size and shape, and external electric field. Sometimes, the bonding force is so strong that the bulk material is not easily broken. Bridging tests on each group revealed that bridging occurred when the net spacing was 20 mm. The tests show that although the interception rate increases significantly with decreasing magnetic rod net spacing, excessively small net spacing can lead to bridging and blockage.

[0050] like Figure 2 As shown, in this embodiment, the steps for obtaining the iron separator test platform include: Step S11: Obtain the iron separator test platform to be tested; prepare to test it. During the test, Step S12: Pour the powder into the iron separator test platform and detect the throughput of the iron separator test platform; Step S13: If the throughput is greater than or equal to 90%, use the iron separator test platform as the iron separator test platform. If the throughput is less than 90%, the spacing between the magnetic rods of the iron separator test platform needs to be increased to improve the throughput of the powder. After the above steps, the powder can quickly pass through the iron separator test platform without accumulating on it, thus improving the accuracy of the iron removal experiment.

[0051] To gain a more intuitive understanding of the magnetic flux and magnetic field line distribution of a single iron separator unit, based on the fundamental equations of magnetic fields and existing finite element analysis models of permanent magnets, ANSYS software was used to perform finite element simulation analysis on the smallest complete unit of a single magnetic rod in the iron separator. For example... Figure 6As shown, in this embodiment, the process between obtaining multiple sets of test materials, each set including powder and metal, and different steps involving different metals in different sets of test materials, and the step of sprinkling each set of test materials from different heights under a first magnetic field strength into the iron separator test platform to obtain the interception rate of each set of test materials at different heights under the first magnetic field strength, includes: Step S61: Performing finite element analysis on the magnetic rod of the iron separator to obtain the position with the maximum magnetic field strength; Step S62: Setting the position with the maximum magnetic field strength of the magnetic rod at the center of the iron separator test platform; Step S63: Aligning the test material with the center of the iron separator test platform. In the above steps, first, the position with the maximum magnetic field strength is found, then the position with the maximum magnetic field strength is set at the center of the iron separator test platform, and finally, the test material is aligned with the center of the iron separator test platform. Since the powder falls in a normal distribution, with more powder in the middle and less in the surrounding areas, the above settings will allow more powder to pass through the center where the magnetic field strength is greater. This will further improve the iron removal effect of the powder and ensure the accuracy of the experiment.

[0052] The magnetic separator consists of several magnetic rods arranged in a specific pattern. Each magnetic rod's smallest complete unit comprises an internal set of end plugs, half-magnetic rings, a magnet, a strong magnetic ring, another magnet, half-magnetic rings, and an end plug. The magnets are arranged with their poles facing each other. The number of magnets and strong magnetic rings can be increased appropriately according to actual design requirements. Using the ANSYS Workbench module and the geometry and Fluent (with Fluent meshing) component system, the magnetic rod specifications were set as follows: magnet length 26mm, magnetic ring thickness 2mm, end plug thickness 2mm, and diameter 25mm, with the center of the strong magnetic ring as the coordinate origin. A finite element analysis model of the smallest complete unit and its overall mesh were established. The iteration value was set to 300. After applying a load, it was clearly observed that the magnetic flux was highest at the strong magnetic ring, while the magnetic flux was very weak at the magnetic field lines parallel to the magnet. This was also visually verified through a saturation adsorption test, showing that in the actual milk powder production process, only the position of the strong magnetic ring on the magnetic rod is the most effective adsorption location.

[0053] like Figure 4As shown, in this embodiment, if the pass rate is greater than or equal to 90%, the step of using the iron separator test platform as the iron separator test platform includes: Step S131: Sprinkling the test material from a fixed height into the iron separator test platform to obtain a first interception rate; Step S132: Changing the spacing of the magnetic rods of the iron separator test platform, and again sprinkling the test material from a fixed height into the iron separator test platform to obtain another first interception rate; S133: Determining the minimum spacing of the magnetic rods based on multiple first interception rates. The spacing of the magnetic rods affects the passage of powder and also affects the iron removal effect. If the spacing of the magnetic rods is small, the powder will not be able to pass through. If the spacing of the magnetic rods is large, the powder can pass through the magnetic rods quickly, but because the powder passes through too quickly, the magnetic rods cannot adsorb all the metal debris, thus affecting the iron removal effect.

[0054] like Figure 3 As shown, in this embodiment, the steps of pouring powder into the iron separator test platform and detecting the throughput of the iron separator test platform include: Step S121: Filling the powder into a container with a smooth inner wall; Step S122: Covering the opening of the container with a baffle; Step S123: Inverting the container so that the baffle is at the bottom and shaking the container; Step S124: Placing the baffle and the container on the iron separator test platform; Step S125: Removing the baffle and observing the flow state of the powder. The powder is filled into a container with a smooth inner wall, gently shaken downwards, and a gasket is placed on top of the container. Then, the container and the container are inverted onto the surface of the magnetic rods, and the gasket is quickly removed to observe the state of the powder. If the powder remains entirely between the two magnetic rods, a bridging phenomenon occurs, posing a potential risk of material blockage during production; if the powder collapses instantly and passes quickly between the magnetic rods, there is no risk of material blockage. The spacing between the magnetic rods can be obtained through the above operations. Specifically, the roughness of the inner wall of the container is less than or equal to Ra0.1.

[0055] like Figure 5As shown, in this embodiment, the step of sprinkling each group of test materials from different heights into the iron separator test platform under the first magnetic field strength to obtain the interception rate of each group of test materials at different heights under the first magnetic field strength includes: S31: removing the magnetic rod from the iron separator test platform; S32: brushing off and collecting the powder adsorbed on the magnetic rod; S33: rinsing and drying the collected powder; S34: weighing the dried metal and comparing it with the initial metal. In this embodiment, the gravimetric method is used to determine the metal interception rate. First, the test materials are rinsed clean and dried in a 60°C oven, then placed in a glass desiccator containing silica desiccant for later use. After the experiment, the powder on the surface of the magnetic rod is removed with a soft brush, the test materials are gently wiped off with lens paper and collected, rinsed clean, and then dried in a 60°C oven. The ratio of the weight of the collected test materials to the initial amount added is the interception rate. This operation yields a more accurate interception rate.

[0056] The step of scattering each set of test materials from different heights into the iron separator testing platform under a first magnetic field strength to obtain the interception rate of each set of test materials at different heights under the first magnetic field strength includes: scattering the test materials from an initial height position into the iron separator testing platform to obtain the interception rate of each set of test materials at the initial height; and measuring again by increasing the test materials at a preset height each time based on the initial height; wherein the preset distance is between 100mm and 300mm. Through the above steps, the interception rate of multiple sets of test materials at different height positions can be obtained. Specifically, in this embodiment, the preset distance is 200mm.

[0057] The steps of adjusting the magnetic field strength of the iron separator testing platform to a second magnetic field strength and then dropping each group of test materials from different heights into the iron separator testing platform to obtain the interception rate of each group of test materials at different heights under the second magnetic field strength include: dropping the test materials from a fixed height into the iron separator testing platform to obtain the interception rate of each group of test materials under the initial magnetic field strength; increasing or decreasing the magnetic field strength of the iron separator testing platform by a preset value and then measuring again; wherein the preset value ranges from 1000GS (GS: Gauss) to 3000GS. Through the above steps, the interception rates of multiple groups of test materials under different magnetic field strengths can be obtained. Specifically, in this embodiment, the preset distance is 2000GS.

[0058] After a long-term collection of metallic foreign objects adsorbed by the iron separator, the factory found that the foreign objects mainly consisted of three types: cast iron (ellipsoidal shape), 304 austenitic stainless steel (flat sheet shape), and 316 austenitic stainless steel (flat sheet shape). This closely matched the actual materials of the production line equipment and material pipelines. The ellipsoidal cast iron pieces were mostly caused by weld detachment from the inner wall of the pipes, while the flat austenitic stainless steel pieces were mostly caused by friction between the screw conveyor and the pipe wall, or by weld detachment. The factory simulated conditions to artificially create metal fragments, which were then selected using an industrial microscope to prepare uniformly sized metal simulation test samples.

[0059] The steps for preparing multiple test samples include: preparing cast iron chips, 304 austenitic stainless steel chips, and 316 austenitic stainless steel chips. The cast iron chips are ellipsoidal, while the 304 and 316 austenitic stainless steel chips are flat. The size of the cast iron chips is limited to 0.1mm×0.1mm×0.1mm to 0.3mm×0.3mm×0.3mm, and the size of the 304 and 316 austenitic stainless steel chips is limited to 0.05mm×0.1mm×0.3mm to 0.2mm×0.3mm×0.5mm. This setup allows for the production of metal chips identical to those found in actual production, facilitating better experimentation and resulting in more accurate data.

[0060] In summary, the technical solution of this embodiment, under the condition of completely simulating the actual production of milk powder factory, based on finite element simulation analysis, through single-factor experiments and matrix analysis, explores the influence of different material falling height, metal type, field strength, and magnetic rod net distance on the effective interception rate of box-type grid iron separator and optimizes the design scheme. In summary, assuming that the minimum acceptable standard is an effective interception rate of ≥80% for cast iron, 304 stainless steel, and 316 stainless steel, the critical design conditions are: (1) When the magnetic rod strong magnetic ring field strength is 10000GS, the falling height is ≤100mm, the number of magnetic rod layers is ≥6, and the net distance is 25mm. (2) When the magnetic rod strong magnetic ring field strength is 14000GS, if the material falling height is ≤100mm, then the number of magnetic rod layers is ≥4, and the net distance is 25mm; if 100m < material falling height ≤300mm, then the number of magnetic rod layers is ≥6, and the net distance is 25mm.

[0061] The experimental data provides a basis for the actual selection, installation, and development of effective metal foreign object control solutions for box-type bar screens in the milk powder industry, greatly filling the data gap. At the same time, it has very important industrial application value for other powdered food materials, such as protein raw materials, powdered oils, starch, and food additives.

[0062] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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 on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0063] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0064] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for deironing of a powder, characterized in that, The method comprises: obtaining a trapper test platform; obtaining a plurality of test objects, wherein each of the test objects comprises a powder and a metal object, and the metal objects in different groups of the test objects are different; spreading each of the test objects in the plurality of test objects into the trapper test platform from different heights under a first magnetic field intensity to obtain an interception rate of each of the test objects under the first magnetic field intensity at different heights; adjusting the magnetic field intensity of the trapper test platform to a second magnetic field intensity, and spreading each of the test objects into the trapper test platform from different heights to obtain an interception rate of each of the test objects under the second magnetic field intensity at different heights; obtaining a table of the interception rates of each of the test objects at different magnetic field intensities and different heights; The step of obtaining a trapper test platform comprises: obtaining a trapper test platform to be tested; pouring the powder into the trapper test platform to be tested, and detecting a passing rate of the trapper test platform; if the passing rate is greater than or equal to 90%, taking the trapper test platform to be tested as the trapper test platform; if the passing rate is less than 90%, increasing the distance between the magnetic bars of the trapper test platform to improve the passing rate of the powder; if the passing rate is greater than or equal to 90%, the step of taking the trapper test platform to be tested as the trapper test platform comprises: spreading the test object into the trapper test platform from a fixed height to obtain a first interception rate; changing the distance between the magnetic bars of the trapper test platform, and again spreading the test object into the trapper test platform from the fixed height to obtain another first interception rate; determining the minimum distance between the magnetic bars according to a plurality of the first interception rates; The step of obtaining a plurality of test objects comprises: preparing cast iron chips, 304 austenitic stainless steel chips and 316 austenitic stainless steel chips; setting the cast iron chips into an ellipsoidal shape, setting the 304 austenitic stainless steel chips and the 316 austenitic stainless steel chips into a flat sheet shape, and limiting the size of the cast iron chips to 0.1mm×0.1mm×0.1mm to 0.3mm×0.3mm×0.3mm, and limiting the size of the 304 austenitic stainless steel chips and the 316 austenitic stainless steel chips to 0.05mm×0.1mm×0.3mm to 0.2mm×0.3mm×0.5mm; between the step of obtaining a plurality of test objects, wherein each of the test objects comprises a powder and a metal object, and the metal objects in different groups of the test objects are different, and the step of spreading each of the test objects in the plurality of test objects into the trapper test platform from different heights under a first magnetic field intensity to obtain an interception rate of each of the test objects under the first magnetic field intensity at different heights, comprises: performing finite element analysis on the magnetic bars of the trapper to obtain a position with the maximum magnetic field intensity; setting the position with the maximum magnetic field intensity of the magnetic bars at a central position of the trapper test platform; aligning the test objects with the central position of the trapper test platform to make the powder fall in a normal distribution; The magnetic bar is set to have a length of 26 mm, a ring thickness of 2 mm, an end plug thickness of 2 mm, and a diameter of 25 mm, with the center of the strong magnetic ring as the coordinate origin, to establish a minimum complete single finite element analysis model and a model overall grid division diagram, and the iteration number is set to 300, and the model is verified through a saturated adsorption test.

2. The method of claim 1, wherein the powder is a powder for a lithium ion secondary battery. The step of pouring the powder into the iron remover test platform and detecting the passing rate of the iron remover test platform includes: loading the powder into a container with smooth inner walls; placing a baffle cover on the opening of the container; turning the container over so that the baffle is below, and shaking the container; placing the baffle and the container on the iron remover test platform; removing the baffle and observing the flow state of the powder.

3. The method of claim 1, wherein the powder is a powder for a lithium ion secondary battery. The step of pouring each group of the test objects in multiple groups of the test objects into the iron remover test platform from different heights under a first magnetic field strength to obtain the interception rate of each group of the test objects at different heights under the first magnetic field strength includes: removing the magnetic bar of the iron remover test platform; brushing off and collecting the powder adsorbed on the magnetic bar; washing and drying the collected powder; weighing the dried metal objects and comparing them with the initial metal objects.

4. The method of claim 1, wherein the powder is a powder for a powder metallurgy process. The step of pouring each group of the test objects in multiple groups of the test objects into the iron remover test platform from different heights under a first magnetic field strength to obtain the interception rate of each group of the test objects at different heights under the first magnetic field strength includes: pouring the test objects into the iron remover test platform from an initial height position to obtain the interception rate of each group of test objects at the initial height; increasing the initial height by a preset height each time and measuring again; wherein the preset distance is between 100 mm and 300 mm.

5. The method of claim 1, wherein the powder is a powder for a powder metallurgy process. The step of adjusting the magnetic field strength of the iron remover test platform to a second magnetic field strength and pouring each group of test objects into the iron remover test platform from different heights to obtain the interception rate of each group of the test objects at different heights under the second magnetic field strength includes: pouring the test objects into the iron remover test platform from a fixed height to obtain the interception rate of each group of test objects at the initial magnetic field strength; increasing or decreasing the magnetic field strength of the iron remover test platform by a preset value and measuring again; wherein the preset value is in the range of 1000 GS to 3000 GS.

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