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CN-121178842-B - Method and system for preparing anisotropic soft magnetic powder by utilizing silicon steel waste

CN121178842BCN 121178842 BCN121178842 BCN 121178842BCN-121178842-B

Abstract

The invention relates to the technical field of magnetic material regeneration and powder metallurgy, and particularly discloses a method and a system for preparing anisotropic soft magnetic powder by utilizing silicon steel waste. The method comprises the steps of performing alkali washing and ultrasonic degreasing on oil-containing silicon steel waste to obtain low-residual oil pretreatment materials, performing primary wet ball milling and online particle size regulation to obtain fine powder, performing decarburization under a hydrogen atmosphere and a temperature gradient, combining online gas analysis to obtain low-impurity alloy powder, performing magnetic field orientation and isostatic compaction to form high-uniformity pressed billets, and finally performing nitriding treatment and layer thickness detection to obtain anisotropic soft magnetic powder. The invention realizes the high-value recycling of the waste material, the process is closed-loop controllable, and the obtained soft magnetic powder has high magnetic conductivity, low loss and good anisotropism.

Inventors

  • XIE JINQIANG
  • CHEN GUO

Assignees

  • 湖南金磁新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20250928

Claims (10)

  1. 1. A method for preparing anisotropic soft magnetic powder from silicon steel scraps, comprising: Performing alkaline washing degreasing through an automatic liquid preparation system with the concentration of NaOH of 5-10wt% based on silicon steel waste with the surface grease content of more than or equal to 5%, and generating pretreated silicon steel waste with the surface residual oil content of less than or equal to 0.5% by combining 30-50kHz ultrasonic auxiliary degreasing and turbidity sensor closed-loop control; Performing primary wet ball milling on pretreated silicon steel waste with the particle size distribution D50=200-500 mu m, wherein the primary wet ball milling comprises the following steps of: adopts gradient steel ball proportion, wherein the ratio of the large-diameter steel ball is Medium diameter Small diameter Forming an impact energy distribution function and optimizing ball milling energy distribution: ; Wherein, the Is the impact energy distribution value; Indexing the steel ball type; is the energy conversion coefficient; The diameter of the steel ball; The diameter of the steel ball is the largest; the mass fraction of the steel ball is; Monitoring slurry concentration by an online concentration meter, and constructing a concentration-grinding efficiency correction factor: ; Wherein: Is a concentration-grinding efficiency correction factor; is the real-time slurry concentration; is the optimal concentration set value; is a concentration deviation tolerance threshold; According to And (3) with Generates dynamic rotational speed control command by product of (2) The rotating speed of the variable-frequency driving motor of the ball mill is adjusted in real time, wherein Performing particle size feedback regulation and control through laser scattering on-line particle size analysis to obtain qualified prealloy powder with D90 less than or equal to 50 mu m; Performing reduction decarburization treatment on the basis of qualified prealloy powder with carbon content of more than 0.1 percent at a temperature gradient of 600-800 ℃ and a hydrogen flow rate of 5-10L/min, and performing online gas analysis by matching with quadrupole mass spectrometry to generate low-impurity alloy powder with oxygen content of less than or equal to 500 ppm; obtaining low-impurity alloy powder with coercive force more than or equal to 10kA/m, performing 0.5-1.5T magnetic field orientation calibration, and constructing an anisotropic compact with density deviation less than or equal to 3% under the isostatic pressure condition of 200-500 MPa; Performing nitriding treatment for 8-24h at a nitriding temperature of 520-580 ℃ and a nitrogen partial pressure of 0.3-0.8MPa from an anisotropic compact with a relative density of more than or equal to 92%, and combining laser copolymerization Jiao Cenghou detection to construct a thickness distribution entropy function: ; Wherein, the Entropy of thickness distribution; index for scanning point; The total scanning point number; Probability density for thickness distribution; is the first The thickness of the nitride layer measured by the point; Probability density for thickness distribution; When (when) When the thickness uniformity of the layer is judged to reach the standard, generating anisotropic soft magnetic powder with the nitriding layer thickness of 50-150 mu m; based on the anisotropic soft magnetic powder with initial magnetic permeability more than or equal to 5000, B-H curve test is executed in a frequency band of 1kHz-1MHz, and a closed-loop monitoring signal system with control accuracy of +/-0.5% is constructed through a process parameter PID optimization algorithm.
  2. 2. The method of claim 1, wherein the silicon steel scrap comprises: The silicon steel waste material specifically comprises industrial waste materials generated in the production or processing process of silicon steel products, and mainly comprises ferrosilicon alloy, wherein the forms comprise stamping scraps, cutting scraps, residual silicon steel sheets and silicon steel core materials disassembled in waste motors or transformers; Is adhered with lubricating grease, rust-proof oil, dust impurity and surface oxide layer introduced in the industrial production process, and contains aluminum, manganese or nonmetallic impurities.
  3. 3. The method of claim 1, wherein the step of producing pretreated silicon steel scrap having a surface residual oil content of 0.5% or less further comprises: obtaining silicon steel waste, and performing alkaline washing liquid soaking treatment with the concentration of sodium hydroxide of 8-12wt% and the temperature of 50-70 ℃ to obtain degreasing waste; Extracting metal particles from the degreasing waste, and performing vibration screening with the screen aperture of 0.5-2mm in gradient arrangement to generate graded silicon steel particles; and (3) carrying out surface passivation treatment on the graded silicon steel particles by using a chromate passivating agent with pH of 8.5-9.5 to generate pretreated silicon steel waste.
  4. 4. The method of claim 1, wherein obtaining acceptable prealloyed powder having a d90≤50 μm further comprises: Obtaining pretreated silicon steel waste, and performing primary ball milling treatment with gradient steel ball proportion of phi 10mm, phi 5mm, phi 2 mm=3:2:1 to obtain coarse powder; separating target particle size particles from coarse grinding powder, and performing secondary wet ball milling at a rotating speed of 200-400rpm to generate fine grinding powder; and (3) carrying out granularity analysis of laser power of 10-15mW on the fine powder to generate qualified prealloy powder.
  5. 5. The method of claim 1, wherein the process of producing the low impurity alloy powder having an oxygen content of 500ppm or less further comprises: Obtaining qualified prealloy powder, regulating and controlling the flow of hydrogen with purity more than or equal to 99.99%, and establishing a reducing atmosphere environment; Extracting decarburization treatment parameters with the temperature gradient of 5-8 ℃ per cm from a reducing atmosphere environment to generate carbon removal powder; And detecting the oxygen content of the carbon removal powder to generate low-impurity alloy powder.
  6. 6. The method of claim 1, wherein the process of constructing an anisotropic compact having a density deviation of 3% or less further comprises: acquiring low-impurity alloy powder, calibrating the magnetic field intensity by 0.5-1.2T, and establishing an orientation magnetic field; extracting parameters of 500-800MPa of pressing pressure from the orientation magnetic field to generate a green body component; The green member was subjected to density detection to produce an anisotropic compact.
  7. 7. The method according to claim 1, wherein the process of producing the anisotropic soft magnetic powder having a nitrided layer thickness of 50 to 150 μm further comprises: obtaining anisotropic green compacts to set nitriding temperature to 500-600 ℃ and establishing a nitriding reaction cavity; Extracting time-air pressure coupling parameters with air pressure of 0.1-0.3MPa from the nitriding reaction cavity to generate a nitriding blank; and (5) measuring the layer thickness of the nitrided blank body to generate the anisotropic soft magnetic powder body.
  8. 8. The method of claim 1, wherein the process of constructing a closed loop supervisory signal system having a control accuracy of ± 0.5% further comprises: Obtaining anisotropic soft magnetic powder, and performing magnetic permeability test of a frequency band of 1kHz-1MHz to generate magnetic performance data; Extracting a process deviation value from the magnetic performance data to carry out parameter correction, and generating an optimized instruction set; and carrying out Modbus/Profibus protocol conversion on the optimized instruction set to generate a closed-loop monitoring signal.
  9. 9. The method according to claim 1, wherein generating the expression of the anisotropic soft magnetic powder having the nitrided layer thickness of 50 to 150 μm comprises: establishing a three-dimensional temperature gradient field: ; Wherein, the Is a three-dimensional temperature gradient field; is the space coordinate of the reaction cavity; Is the reference temperature; is the maximum temperature gradient amplitude; , , Is a reaction cavity size parameter; Gas flow was described using the modified Navie-Stokes equation: ; Wherein, the Is the partial derivative of air pressure with respect to time; is a divergence operator; Is the real-time air pressure; is an airflow velocity field; supplying a flow rate for hydrogen; is the volume of the reaction cavity; Is a pressure adjustment coefficient; Setting a target air pressure value; Is a time variable; constructing a thickness distribution entropy function: ; Wherein, the Entropy of thickness distribution; index for scanning point; The total scanning point number; Probability density for thickness distribution; is the first The thickness of the nitride layer measured by the point; Probability density for thickness distribution; When (when) And when the thickness uniformity of the layer is judged to reach the standard, generating the anisotropic soft magnetic powder.
  10. 10. A system for preparing anisotropic soft magnetic powder from silicon steel scraps, applied to the method of any one of claims 1 to 9, comprising, The pretreatment silicon steel waste acquisition module is used for performing primary ball milling treatment to generate coarse powder; the wet ball milling module is connected with the pretreated silicon steel waste acquisition module and is used for carrying out secondary wet ball milling on the coarse powder to generate fine powder; The laser particle size analysis module is connected with the wet ball milling module and is used for detecting the particle size of the fine powder to generate qualified prealloy powder; the nitriding reaction cavity construction module is used for setting nitriding temperature parameters according to the anisotropic pressed compact; The nitriding treatment module is connected with the nitriding reaction cavity construction module and is used for extracting time-air pressure coupling parameters to generate a nitriding blank; the layer thickness measuring module is connected with the nitriding treatment module and is used for analyzing the nitrided blank body to generate anisotropic soft magnetic powder; the process correction module is connected with the layer thickness measurement module and is used for comparing the measurement result with a threshold value and outputting a correction instruction; and the strategy updating module is connected with the process correcting module and is used for adjusting nitriding temperature gradient and updating a process strategy table.

Description

Method and system for preparing anisotropic soft magnetic powder by utilizing silicon steel waste Technical Field The invention relates to the technical field of magnetic material regeneration and powder metallurgy, in particular to a method and a system for preparing anisotropic soft magnetic powder by utilizing silicon steel waste. Background In the field of recycling of silicon steel waste, the existing method generally treats the waste through mechanical crushing and a single ball milling process, combines decarburization, molding and sintering processes to prepare soft magnetic powder, and has the limitations of low ball milling efficiency, discrete powder particle size distribution, poor magnetic property consistency and the like. The existing method mostly adopts fixed steel ball proportion and single-stage wet ball milling, and is easy to generate pain points such as uneven energy distribution, uncontrolled fine grinding powder morphology and the like in the progressive refinement process of silicon steel waste, so that the requirements of high magnetic conductivity and low coercivity of the anisotropic soft magnetic powder are difficult to meet. Aiming at the gradient crushing and nitriding strengthening process link of the pretreated silicon steel waste, the prior art generally lacks the capability of serial cooperative control and nitriding parameter dynamic coupling of multi-stage ball milling equipment, and is difficult to form a continuous regulation and control flow of coarse grinding, fine grinding, decarburization and nitriding under the high-valued regeneration scene of the waste, so that the grain boundary oxidation risk of prealloy powder is increased, and the thickness fluctuation of the nitriding layer is remarkable. Disclosure of Invention The invention provides a method and a system for preparing anisotropic soft magnetic powder by utilizing silicon steel waste, which are used for solving the problem of how to realize the efficient preparation of coarse powder by using a gradient steel ball energy distribution model and concentration self-adaptive adjustment under a multistage serial process of a wet ball mill based on a pretreatment and ball milling system of the silicon steel waste. In order to solve the technical problems, the invention provides a method for preparing anisotropic soft magnetic powder by using silicon steel waste, which comprises the following steps: Performing alkaline washing degreasing through an automatic liquid preparation system with the concentration of NaOH of 5-10wt% based on silicon steel waste with the surface grease content of more than or equal to 5%, and generating pretreated silicon steel waste with the surface residual oil content of less than or equal to 0.5% by combining 30-50kHz ultrasonic auxiliary degreasing and turbidity sensor closed-loop control; Performing primary wet ball milling on pretreated silicon steel waste with the grain size distribution D50=200-500 mu m, performing on-line grain size analysis through laser scattering to perform grain size feedback regulation and control, and obtaining qualified prealloy powder with the D90 less than or equal to 50 mu m, wherein the primary wet ball milling comprises phi 10-20mm gradient steel balls; Performing reduction decarburization treatment on the basis of qualified prealloy powder with carbon content of more than 0.1 percent at a temperature gradient of 600-800 ℃ and a hydrogen flow rate of 5-10L/min, and performing online gas analysis by matching with quadrupole mass spectrometry to generate low-impurity alloy powder with oxygen content of less than or equal to 500 ppm; obtaining low-impurity alloy powder with coercive force more than or equal to 10kA/m, performing 0.5-1.5T magnetic field orientation calibration, and constructing an anisotropic compact with density deviation less than or equal to 3% under the isostatic pressure condition of 200-500 MPa; Performing nitriding treatment for 8-24h at the nitriding temperature of 520-580 ℃ and the nitrogen partial pressure of 0.3-0.8MPa from the anisotropic compact with the relative density of more than or equal to 92%, and detecting by combining with laser copolymerization Jiao Cenghou to generate anisotropic soft magnetic powder with the thickness of a nitriding layer of 50-150 mu m; based on the anisotropic soft magnetic powder with initial magnetic permeability more than or equal to 5000, B-H curve test is executed in a frequency band of 1kHz-1MHz, and a closed-loop monitoring signal system with control accuracy of +/-0.5% is constructed through a process parameter PID optimization algorithm. Further, the silicon steel scrap includes: The silicon steel waste material specifically comprises industrial waste materials generated in the production or processing process of silicon steel products, and mainly comprises ferrosilicon alloy, wherein the forms comprise stamping scraps, cutting scraps, residual silicon steel sheets and silicon steel cor