Impurity removal method for magnetic material production

Abstract

The invention discloses an impurity removal method for magnetic material production, and belongs to the technical field of magnetic material production. Comprising the following steps: a primary impurity removal process: weighing and proportioning raw materials, feeding, and carrying out ball milling and refining to obtain refined slurry; a horizontal vibrating screen with double layers of filter screens is arranged to remove impurities from the refined slurry, large particles are isolated, and the slurry with impurities removed is obtained; a second-stage impurity removal process: concentrating, drying and dispersing the slurry subjected to the first-stage impurity removal by a crusher to obtain material powder; in the second-stage impurity removal process, the material powder is subjected to second-stage filtering impurity removal through a horizontal vibrating screen provided with an ultrasonic excitation screen, and the material powder subjected to impurity removal is obtained; and a third-stage preventive impurity removal process: carrying out third-stage preventive impurity removal on the material powder subjected to the second-stage impurity removal through a screen, and then packaging. And after the three-stage impurity removal, impurities can be effectively treated, so that the product quality stability is improved, and very high practicability is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic material production, and in particular relates to a method for removing impurities from magnetic material production. Background Art

[0002] As a kind of magnetic material, dry-process sintered permanent ferrite is made by directly filling dry pressed magnetic powder into the molding space of the molding device, pressing and molding in a magnetic field, and then sintering at high temperature. It has the advantages of fast pressing speed, high production efficiency, and easy automation molding. It is widely used in various miniaturized motors. However, due to the direct use of dry powder and miniaturization, the dry pressed magnetic powder raw materials used have extremely high requirements on impurities, which directly affects the quality of the product. Generally, the minimum requirement for product powder is to pass the 120-mesh sieve. In the current production process of dry pressed magnetic powder, it needs to go through fine grinding, concentration, drying, dispersion and other processes. Different types of impurities will be generated in this process. How to effectively remove impurities and prevent impurities from flowing into the final product is a problem faced by companies producing dry pressed magnetic powder.

[0003] For the prevention and control of impurities in dry-pressed magnetic powder, it is generally only aimed at some fine iron filings and smaller irregular steel balls and other impurities brought out during the transfer of the raw material ball-milled slurry to the storage tank. In order to solve the above problems, a higher mesh screen is added during the transfer of the refined slurry. Generally, a screen of 120 mesh or above is required. Some companies have air flow screens before packaging.

[0004] In the process of transferring the refined slurry, a screen with a mesh size of 120 or above is configured to separate impurities. Because the impact force of the slurry on the screen is large, the screen aperture is small, and the mesh wires that make up the screen are relatively fine, about 0.08mm, it is very easy to cause blockage and mesh wire rupture, and frequent cleaning and replacement are required. In the process of dry-pressed magnetic powder production, impurities are removed during ball milling. When the refined slurry is transferred to the storage tank, some fine iron filings and smaller irregular steel balls will be brought out with the slurry. In the process of slurry concentration and drying, the components of the internal structure of the concentration and drying equipment are in a state of high pressure or high temperature baking for a long time, which will cause fatigue and shedding or cracking of some structures, and produce some iron filings impurities. Although an airflow screen is set before the powder packaging, it is very easy to damage the mesh surface of the airflow screen, resulting in frequent replacement of the screen, and some materials are agglomerated and difficult to screen out, resulting in the problem that more than 2% of the materials need to be reworked and re-screened. Summary of the invention

[0005] The object of the present invention is to provide a method for removing impurities in the production of magnetic materials, which can effectively remove various impurities generated in the production process of dry-pressed magnetic materials.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for removing impurities from magnetic material production comprises the following steps:

[0008] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer filter screen is configured to remove impurities from the refined slurry and isolate larger particles to obtain a slurry after impurities are removed.

[0009] Since the slurry has a certain kinetic energy impact during the raw material transfer process, the first layer of 80-mesh screen is used to remove impurities and eliminate impact force. The second layer of screen is a preventive screen to effectively isolate large particles from flowing into the next process when the first layer is damaged.

[0010] Secondary impurity removal process: the slurry after primary impurity removal is concentrated, dried, and dispersed by a pulverizer to obtain material powder; the secondary impurity removal process uses a horizontal vibrating screen equipped with an ultrasonic excitation screen to perform secondary filtration and impurity removal on the material powder dispersed by the pulverizer to obtain impurity-free material powder;

[0011] Since the powder is generally 0.5-2μm, a general vibrating screen with a 120-mesh screen will cause the powder to agglomerate and be difficult to screen, so ultrasonic excitation is used; the ultrasonic excitation transmits 18KHz mechanical vibration to the rod resonator, and then evenly transmits it to the screen surface, so that the ultrafine powder is subjected to huge ultrasonic acceleration, thereby suppressing the factors of adhesion, friction, flat fall, wedging and other blocking factors, improving the efficiency of the screening machine and the efficiency of the screen cleaning, and achieving the purpose of efficient screening and screen cleaning; it solves the problem that the powder is removed by an air flow screen after being crushed by a high-speed crusher, but impurities can easily damage the mesh surface of the air flow screen, causing the screen to be damaged and replaced every 3-5 days, and some materials are agglomerated and difficult to be screened, resulting in more than 2% of the materials needing to be reworked and re-screened.

[0012] The three-level preventive impurity removal process, after the second-level impurity removal, the powder passes through the screen for the third-level preventive impurity removal and then is packaged.

[0013] This process can prevent the outflow of impurities due to the damage of the vibrating screen in the secondary impurity removal process that is not discovered in time. After the powder is dispersed by ultrasound in the secondary impurity removal, the material does not agglomerate and can easily pass through the airflow screen, effectively avoiding the problem of powder being difficult to screen out in the airflow screen and the frequent damage and replacement of the screen, and basically no material needs to be re-screened.

[0014] Furthermore, the aperture of the double-layer screen in the primary impurity removal process is 60-100 mesh.

[0015] Furthermore, the diameter of the wire of the double-layer screen in the primary impurity removal process is between 0.1-0.15 mm. The wire of the filter screen is thickened, which can effectively avoid frequent damage to the screen.

[0016] Furthermore, the concentration of the slurry after concentration in the secondary impurity removal process is 80%-90%.

[0017] Furthermore, the drying temperature in the secondary impurity removal process is 450-550°C.

[0018] Furthermore, in the secondary impurity removal process, the rotation speed of the pulverizer is 1500-2000r / min.

[0019] Furthermore, the aperture of the screen in the secondary impurity removal process is 120-150 meshes.

[0020] Furthermore, the frequency of ultrasonic excitation in the secondary impurity removal process is 16-20KHz.

[0021] Furthermore, the filter screen in the primary impurity removal process and the secondary impurity removal process is a horizontal vibrating screen with an amplitude of 3-5 mm.

[0022] Furthermore, the aperture of the screen in the three-level preventive impurity removal process is 120-150 meshes.

[0023] Furthermore, the filter screen in the three-stage preventive impurity removal process is a vertical rotary screen with a power of 7-10KW.

[0024] Beneficial effects of the present invention:

[0025] (1) The present invention provides a method for removing impurities from magnetic material production, which effectively intervenes and controls various impurities generated during production, and the impurity control at each stage is stable and effective, which can effectively improve production efficiency, save production costs, stabilize product performance, and improve product quality.

[0026] (2) The first-level impurity removal adopted by the present invention adopts a double-layer 80-mesh coarse mesh screen instead of a 120-mesh screen, so that the material can be screened more smoothly and the mesh is not easily damaged; the second-level impurity removal is further carried out on the basis of the first-level impurity removal, and an ultrasonic excitation method is used to avoid agglomeration and clogging of the dry powder, thereby improving the efficiency of the screening machine and the efficiency of the screen cleaning, thereby achieving the dual purposes of efficient screening and screen cleaning.

[0027] (3) The three-stage impurity removal adopted by the present invention is a preventive impurity removal measure to prevent impurities from flowing out into the finished product. This process can prevent the outflow of impurities caused by the damage of the vibrating screen in the secondary impurity removal process and the failure to find it in time. After the powder is dispersed by ultrasonic wave in the secondary impurity removal, the material does not agglomerate and can easily pass through the airflow screen, effectively avoiding the problem that the powder is difficult to screen out in the airflow screen and the screen needs to be frequently damaged and replaced. After this three-stage impurity removal, various impurities generated by dry-pressed magnetic materials during the production process can be effectively handled, and frequent inspection and replacement of the screen can be effectively avoided, thereby extending the service life of the screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 The present invention is a flow chart of the dry pressed magnetic powder production and impurity removal method. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer 80-mesh filter is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.13mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed.

[0033] Secondary impurity removal process: the slurry after primary impurity removal is concentrated into 85% concentration slurry, and then dried at 500℃ into 0.5-3mm particles, and then dispersed into powder by a high-speed crusher with a speed of 1500-2000r / min. The powder dispersed by the high-speed crusher is then filtered and impurities removed by a horizontal vibrating screen with a 120-mesh screen equipped with ultrasonic excitation. The frequency of ultrasonic excitation is 18KHz, and the amplitude of the vibrating screen is 4mm, so as to obtain the impurity-free powder;

[0034] The three-level preventive impurity removal process, after the second-level impurity removal, the powder passes through a 120-mesh, 8KW vertical rotary screen for the third-level preventive impurity removal and then is packaged.

[0035] The above process flow is as follows Figure 1 shown.

[0036] Example 2

[0037] Compared with Example 1, the present embodiment is different in that the apertures of the double-layer sieves in the primary impurity removal process are changed to 100 mesh and 60 mesh. The specific implementation steps are as follows:

[0038] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry; when the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer filter screen (the first layer is 100 mesh, the second layer is 60 mesh) is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.13mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed;

[0039] The remaining raw materials and preparation process remain the same as in Example 1.

[0040] Example 3

[0041] Compared with Example 1, the present embodiment is different in that the apertures of the double-layer sieves in the primary impurity removal process are changed to 60 mesh and 100 mesh. The specific implementation steps are as follows:

[0042] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry; when the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer filter screen (the first layer is 60 mesh, the second layer is 100 mesh) is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.13mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed;

[0043] The remaining raw materials and preparation process remain the same as in Example 1.

[0044] Example 4

[0045] Compared with Example 1, the difference between this embodiment and Example 1 is that the mesh diameter of the double-layer screen in the primary impurity removal process is changed to 0.1 mm. The specific implementation steps are as follows:

[0046] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer 80-mesh filter screen is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.1mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed.

[0047] The remaining raw materials and preparation process remain the same as in Example 1.

[0048] Example 5

[0049] Compared with Example 1, the difference between this embodiment and Example 1 is that the mesh diameter of the double-layer screen in the primary impurity removal process is changed to 0.15 mm. The specific implementation steps are as follows:

[0050] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer 80-mesh filter screen is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.15mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed.

[0051] The remaining raw materials and preparation process remain the same as in Example 1.

[0052] Example 6

[0053] Compared with Example 1, this embodiment differs in that the sieve amplitude in the primary impurity removal process and the secondary impurity removal process is changed to 3 mm. The specific implementation steps are as follows:

[0054] The remaining raw materials and preparation process remain the same as in Example 1.

[0055] Example 7

[0056] Compared with Example 1, the present embodiment is different in that the amplitude of the filter screen in the primary impurity removal process and the secondary impurity removal process is changed to 5 mm.

[0057] The remaining raw materials and preparation process remain the same as in Example 1.

[0058] Comparative Example 1

[0059] Compared with Example 1, the difference between this comparative example is that the double-layer 80-mesh filter screen in the primary impurity removal process is replaced with a single-layer 120-mesh filter screen. The specific implementation steps are as follows:

[0060] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a single-layer 120-layer filter screen is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.13mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed.

[0061] The remaining raw materials and preparation process remain the same as in Example 1.

[0062] Comparative Example 2

[0063] Compared with Example 1, the difference between this comparative example and Example 1 is that the horizontal vibrating screen equipped with a 120-mesh screen with ultrasonic excitation in the secondary impurity removal process is replaced with an air flow screen equipped with a 120-mesh screen. The specific implementation steps are as follows:

[0064] Secondary impurity removal process: the slurry after primary impurity removal is concentrated into 85% concentration slurry, and then dried at 500℃ into 0.5-3mm particles, and then dispersed into powder by a high-speed pulverizer with a speed of 1500-2000r / min, and then the powder dispersed by the high-speed pulverizer is filtered and impurities are removed by a second-level air flow sieve equipped with a 120-mesh screen to obtain the impurity-free powder;

[0065] The remaining raw materials and preparation process remain the same as in Example 1.

[0066] Comparative Example 3

[0067] This comparative example is based on comparative example 2, in which the double-layer 80-mesh filter screen in the primary impurity removal process is replaced with a single-layer 120-mesh filter screen, and the specific implementation steps are as follows:

[0068] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a single-layer 120-layer filter screen is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.13mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed.

[0069] Secondary impurity removal process: the slurry after primary impurity removal is concentrated into 85% concentration slurry, and then dried at 500℃ into 0.5-3mm particles, and then dispersed into powder by a high-speed pulverizer with a speed of 1500-2000r / min, and then the powder dispersed by the high-speed pulverizer is filtered and impurities are removed by a second-level air flow sieve equipped with a 120-mesh screen to obtain the impurity-free powder;

[0070] The remaining raw materials and preparation process remain the same as in Example 1.

[0071] Comparative Example 4

[0072] Compared with Example 1, this comparative example is different in that the three-level preventive impurity removal process is not performed, and the specific implementation steps are as follows:

[0073] In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry. When the refined slurry is transferred to the storage tank, a horizontal vibrating screen with a double-layer 80-mesh filter is configured to remove impurities from the refined slurry. The mesh diameter of the double-layer screen is 0.13mm, and the amplitude is 4mm, which isolates larger particles to obtain a slurry after impurities are removed.

[0074] In the secondary impurity removal process, the slurry after the primary impurity removal is concentrated into a slurry with a concentration of 85%, and then dried at 500°C into particles of 0.5-3mm. It is then dispersed into powder by a high-speed crusher with a rotation speed of 1500-2000r / min. The powder dispersed by the high-speed crusher is then filtered and impurities removed by a secondary method using a horizontal vibrating screen with a 120-mesh screen equipped with ultrasonic excitation. The frequency of the ultrasonic excitation is 18KHz, and the amplitude of the vibrating screen is 4mm to obtain the impurity-free powder.

[0075] The methods provided in Examples 1 to 7 and Comparative Examples 1 to 4 were tested for impurity removal, and the results are shown in Table 1 (yield = qualified weight / feed weight*100%, unqualified materials need to be rescreened):

[0076] Table 1

[0077]

[0078]

[0079] According to the embodiments, comparative examples and the data in Table 1, it can be seen that the difference between embodiments 2-3 and embodiment 1 is that the apertures of the double-layer screen are different, the difference between embodiments 4-5 and embodiment 1 is that the mesh diameter of the double-layer screen is changed, and the difference between embodiments 6-7 and embodiment 1 is that the amplitude of the filter screen is changed in the first and second stage processes. From the results, the particle size and yield of the material after screening show good effects.

[0080] Compared with Example 1, the double-layer 80 mesh is changed to a single-layer 120 mesh. Although the aperture is smaller, the first layer of 80 mesh screen in the double-layer 80 mesh is used to remove impurities and eliminate impact force. The second layer of screen is a preventive screen to prevent the first layer from being damaged and effectively isolate large particles from flowing into the next process, so that the material can be screened more smoothly and the mesh is not easy to be damaged, thereby increasing the yield accordingly. Compared with Example 2, Example 1 uses ultrasonic excitation to avoid impurities being easily damaged by the airflow screen. The dry powder agglomerates and blocks the net, which improves the efficiency of the screening machine and the net cleaning efficiency, achieving the dual purposes of efficient screening and net cleaning; Comparative Example 3 combined with Comparative Examples 1-2 compared with Example 1 reflects the synergistic effect of the first and second level impurity removal processes, which is also true from the results; Comparative Example 4 compared with Example 1, after not performing the third level preventive impurity removal process, the particle size after screening becomes larger accordingly. This is because the third level preventive impurity removal process can prevent the impurities caused by the damage of the vibrating screen in the second level impurity removal process not being discovered in time from flowing into the finished product, thereby improving production efficiency and stabilizing product performance.

[0081] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0082] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for removing impurities in magnetic material production, characterized in that: The steps include: In the first-level impurity removal process, the raw materials are weighed and proportioned, and ball-milled to obtain a refined slurry; impurities are removed using a double-layer filter screen to obtain a slurry after impurities are removed; In the secondary impurity removal process, the impurity-removed slurry is concentrated, dried, and dispersed in a pulverizer to obtain a powder; a screen equipped with ultrasonic excitation is used to perform secondary filtration and impurity removal on the powder to obtain a powder after impurities are removed; The third-level preventive impurity removal process is to pass the cleaned powder through a sieve for the third-level preventive impurity removal and then package it.

2. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The aperture of the double-layer screen in the primary impurity removal process is 60-100 meshes.

3. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The mesh diameter of the double-layer screen in the primary impurity removal process is between 0.1-0.15 mm.

4. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The concentration of the slurry after concentration in the secondary impurity removal process is 80%-90%.

5. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The drying temperature in the secondary impurity removal process is 450-550°C.

6. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The rotation speed of the pulverizer in the secondary impurity removal process is 1500-2000r / min.

7. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The aperture of the screen in the secondary impurity removal process is 120-150 meshes.

8. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The frequency of ultrasonic excitation in the secondary impurity removal process is 16-20KHz.

9. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The filter screen in the primary impurity removal process and the secondary impurity removal process is a horizontal vibrating screen with an amplitude of 3-5 mm.

10. A method for removing impurities from magnetic material production according to claim 1, characterized in that: The aperture of the screen in the three-stage preventive impurity removal process is 120-150 meshes; the filter screen in the three-stage preventive impurity removal process is a vertical rotary screen with a power of 7-10KW.

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