A method for recycling a permanent magnet strontium ferrite grinding material

Abstract

The present invention relates to a method for recycling permanent magnet strontium ferrite grinding materials, belonging to the technical field of recycling permanent magnet strontium ferrite grinding materials. The method for recycling permanent magnet strontium ferrite grinding materials recycles the permanent magnet strontium ferrite grinding materials through steps such as dispersing, drying, and ball milling using an ultrasonic oscillation sieve machine, thereby solving the problems existing in the existing recycling methods of permanent magnet strontium ferrite grinding materials, such as large impurity components, poor quality control of recycled materials, environmental pollution, and poor quality of the prepared finished products, and is particularly suitable for the production needs of enterprises.

Description

Technical Field

[0001] The present invention relates to a method for recycling permanent magnet strontium ferrite grinding materials, belonging to the technical field of recycling permanent magnet strontium ferrite grinding materials. Background Art

[0002] Permanent magnet strontium ferrite, also known as hard ferrite, only needs to be externally provided with a single magnetization energy to generate a stable magnetic field, thereby continuously providing magnetic energy to the outside. Permanent magnet strontium ferrite is bonded to the stator or rotor of a micro-special motor, mainly providing a permanent magnetic field for the micro-special motor, enabling it to drive the stator or rotor to rotate rapidly under a high-frequency alternating electric field, thereby generating torque and driving the equipment to operate. Permanent magnet ferrite is made from SrO or BaO and Fe 2 O 3 as raw materials through ceramic processes (pre-burning, crushing, secondary ball milling, wet orientation pressing, sintering, and grinding). It is a functional material with a wide hysteresis loop, high coercivity, high remanence, and can maintain a constant magnetism once magnetized.

[0003] The permanent magnet strontium ferrite formed by wet molding is produced through processes such as magnetic field orientation molding pressing, sintering, and grinding after the slurry is precipitated and dehydrated to 25 - 35% after secondary ball milling. During the sintering process, the permanent magnet strontium ferrite magnetic tiles will undergo a large amount of shrinkage and deformation due to the volatilization of moisture and additives (CaCO 3 , H 3 BO 3 ). This makes it necessary for the ferrite magnetic tiles to undergo grinding processing to meet the usage requirements, and a large amount of grinding materials will be generated during the grinding process. The grinding materials of permanent magnet strontium ferrite have a high recycling value, which can help enterprises control costs and enhance the market competitiveness of products. Therefore, enterprises will recycle the grinding materials of permanent magnet strontium ferrite.

[0004] However, the existing methods for recycling permanent magnet strontium ferrite grinding materials, such as the devices for recycling permanent magnet strontium ferrite grinding materials disclosed in the utility model patents with the authorization publication numbers CN204171870U and CN213136364U, although they can meet the needs of recycling permanent magnet strontium ferrite grinding materials to a certain extent, have the following problems:

[0005] 1. The permanent magnet strontium ferrite grinding materials contain impurities such as diamond and silicate. The existing recycling methods cannot disperse and recycle the magnetic powder clusters in the grinding materials, resulting in a large proportion of recycled impurities.

[0006] 2. The existing method for recycling permanent magnet strontium ferrite grinding materials is to precipitate them in a sedimentation tower and then recycle them. However, for the recycled materials obtained by this method, the water content needs to be controlled. Therefore, the recycled materials must be precipitated or dried in the sun. This makes it easy to introduce impurities during the transportation and drying process of the recycled materials, occupies some production sites, and even causes dust pollution in the workshop.

[0007] 3. After the existing permanent magnet strontium ferrite grinding materials are recycled, they are directly used as raw materials for the production of permanent magnet strontium ferrite. The particle size and moisture of the grinding materials cannot be accurately controlled, resulting in an inability to control the ratio between the internal components (steel balls, materials, additives) of the grinding materials. Moreover, high requirements are imposed on the pressing process and sintering process, and the production process needs to be frequently modified. Therefore, it is difficult to ensure the uniformity and repeatability of the prepared permanent magnet strontium ferrite, and there are problems with poor product quality, reducing the market competitiveness of the enterprise's products.

[0008] Therefore, in view of the existing recycling methods for permanent magnet strontium ferrite grinding materials, it is necessary to develop a new recycling method to solve the above problems existing in the existing recycling methods. Summary of the Invention

[0009] The purpose of the present invention is to provide a recycling method for permanent magnet strontium ferrite grinding materials to solve the problems of large impurity components, poor quality control of recycled materials, environmental pollution, and poor quality of the prepared finished products existing in the existing recycling methods for permanent magnet strontium ferrite grinding materials.

[0010] The technical solution of the present invention is as follows:

[0011] A recycling method for permanent magnet strontium ferrite grinding materials, characterized in that the recycling method includes the following steps:

[0012] Step 1: Precipitation and recycling;

[0013] Collect the grinding materials generated during the grinding process of permanent magnet strontium ferrite. The grinding materials are collected together with the cooling water into a sedimentation tower. After the grinding materials are left standing in the sedimentation tower for a period of time, they are recycled.

[0014] Step 2: Oscillation and sieving;

[0015] Use an ultrasonic oscillation sieving machine to oscillate and screen the recycled grinding materials in Step 1 for 30 - 40 minutes using 120 - mesh and 300 - mesh sieve meshes under the action of ultrasonic waves; remove the over - size materials on the surface of the 120 - mesh sieve mesh as impurities, recycle the over - size materials on the surface of the 300 - mesh sieve mesh as coarse grinding materials, and recycle the materials under the lower surface of the 300 - mesh sieve mesh as fine grinding materials;

[0016] Step 3: Drying

[0017] The coarse grinding material and the fine grinding material obtained by sieving in Step 2 are respectively introduced into a drum dryer. The drum dryer is 6 m long, with an inclination angle of 30°. The feed inlet is 1 m higher than the discharge outlet. The feed inlet is provided with an exhaust port, and there is a dust removal device above the exhaust port. Inside the drum dryer, there are guide steel sheets welded. When rotating forward, the guide steel sheets make the material move towards the discharge outlet, and when rotating in reverse, the material also moves towards the discharge outlet. Control the heating temperature of the drum dryer at 180 - 220 °C, the rotation speed at 5 r / min, and control the forward and reverse rotations to alternate in sequence for 30 - 40 min. In this way, the dried coarse grinding material and the dried fine grinding material can be obtained.

[0018] Step 4: Ball milling

[0019] Put grinding material, water and steel balls into the ball milling tank according to the weight ratio of (0.8 - 1.2):(1.3 - 1.7):(5 - 7); among them, the weight ratio of the dried coarse grinding material and the fine grinding material in the grinding material is (7 - 9):(3 - 1); the diameters of the steel balls are 6 mm, 8 mm, and 10 mm, and ensure that the total surface areas of the three added are equal. The ball milling speed is 40 - 50 r / min. After ball milling for 8 - 12 h, add a certain proportion of additives according to the total weight of the grinding material.

[0020] Step 5: Particle size control;

[0021] During the process of Step 4, use a laser particle size analyzer to analyze the particle size of the grinding material after ball milling. When the particle size D90 of the ball - milled grinding material ≤ 0.85 μm, D50 is between 0.72 - 0.76 μm, and D10 ≥ 0.68 μm, close the ball milling tank.

[0022] Step 6: Sedimentation;

[0023] After the grinding material goes through Step 4 and Step 5, use a suction device to pump the grinding material in the ball milling tank into the sedimentation tower. After standing for 12 - 18 h, the grinding material moves towards the bottom of the sedimentation tower under the action of gravity. At this time, extract the water in the upper part of the sedimentation tower, and control the water content of the grinding material in the sedimentation tower to be between 27 - 37% to obtain the grinding slurry.

[0024] Step 7: Pressing and sintering;

[0025] Wet - process orientation pressing and forming: There is a discharge outlet at the lower part of the sedimentation tower in Step 6. Take the grinding slurry and pour it into the hopper of the press. The press closes the mold, injects the grinding slurry, starts the orientation magnetic field, and the particles of the grinding slurry rotate in unison. The lower punch of the press moves, the water is discharged, and the grinding slurry forms a certain shape. Finally, keep the pressure. Subsequently, the orientation magnetic field is 2.0 - 2.4 T, the duration is 15 - 20 s, and the mold - closing pressure - keeping time is 15 - 20 s to obtain the pressed blank.

[0026] The advantages of the present invention are:

[0027] The recycling method of the permanent magnet strontium ferrite grinding material recycles the permanent magnet strontium ferrite grinding material through steps such as dispersion, drying, and ball milling using an ultrasonic oscillation sieve machine, thereby solving the problems existing in the existing recycling methods of the permanent magnet strontium ferrite grinding material, such as large impurity components, poor quality control of the recycled material, environmental pollution, and poor quality of the obtained finished product, and is particularly suitable for the production needs of enterprises. Brief Description of the Drawings

[0028] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0029] The recycling method of the permanent magnet strontium ferrite grinding material is characterized in that: the recycling method includes the following steps:

[0030] Step 1: Precipitation recycling;

[0031] Collect the grinding material generated during the grinding process of the permanent magnet strontium ferrite. The grinding material is collected together with the cooling water into the precipitation tower. After the grinding material stands in the precipitation tower for a period of time, it is recycled; the purpose of using the precipitation tower to recycle the grinding material is to remove the mobile water solvent by dissolving the mobile water solvent on the surface of the grinding material with the cooling water in the precipitation tower.

[0032] Step 2: Oscillation sieving;

[0033] Use an ultrasonic oscillation sieve machine to perform oscillating screening on the recycled grinding material in Step 1 for 30 - 40 minutes using 120mesh and 300mesh sieve meshes under the action of ultrasonic waves; remove the oversize materials on the surface of the 120mesh sieve mesh as impurities, recycle the oversize materials on the surface of the 300mesh sieve mesh as coarse grinding materials, and recycle the materials on the lower surface of the 300mesh sieve mesh as fine grinding materials;

[0034] The ultrasonic oscillation sieve machine is produced by Henan Ruite Company, and the model is RGP - 1200. The purpose of using the ultrasonic oscillation sieve machine to screen the grinding material is:

[0035] 1. Ultrasonically disperse and wet - screen the agglomerated magnetic powder clusters in the grinding material. After the ferrite magnetic tiles are subjected to orientation forming and sintering, some of them have weak magnetism. The grinding powder generated after grinding will agglomerate into magnetic powder clusters due to the action of the magnetic field in water. The particle sizes in the magnetic powder clusters are different, and it is not easy to disperse in the subsequent ball - milling process. In the subsequent pressing, the magnetic powder clusters are difficult to rotate under the magnetic field pulse, and in the sintering of the magnetic tiles, this part will become the area where cracks are generated and expanded due to inconsistent shrinkage. The above will lead to weak magnetic properties and poor mechanical properties of the magnetic tiles. After adding ultrasonic oscillation, the screening and water removal of the ball - milling material solution can be accelerated.

[0036] 2. There are emery particles that fall off the grinding wheel during grinding, hard silicates, and impurities that fall off the grinding machine tooling fixtures in the grinding material. By taking advantage of the relatively large particle size of the impurities, this application uses a 120-mesh filter screen to sieve and remove them, preventing them from entering the subsequent production steps. This avoids the problem that impurities entering the subsequent ball mill can damage the steel balls and the ball mill, shortening the service life of the equipment. Additionally, it reduces the risk that impurities existing at the grain boundaries during sintering hinder the liquid-phase diffusion, causing abnormal growth of the ferrite tile grains, resulting in uneven magnetic properties, uneven shrinkage of the ferrite tile after cooling, and cracks at the impurity sites.

[0037] 3. Use a 300-mesh screen to screen the particle size of the grinding material. During the grinding process, there are rough grinding and fine grinding. The emery particle size of the grinding wheel for rough grinding is larger, so the particle size of the grinding material is larger. Similarly, the particle size of the grinding material for fine grinding is finer. Moreover, when the ferrite tile first contacts the grinding wheel, due to the large cutting amount, the grinding material particles are large, and then as the cutting amount decreases, the particle size of the grinding material gradually decreases. In order to produce high-quality ferrite tiles, the particle size is thus distinguished. The particle size of the grinding material generated during rough grinding of the ferrite tile is 60 - 100 μm, and the particle size of the grinding material generated during fine grinding is below 50 μm, and both are normally distributed. However, the magnetic domain of the permanent magnet strontium ferrite is about 0.95 - 1.15 μm, and the particle size control of the ball milling process is 0.7 - 0.8 μm. Therefore, it is necessary to perform ball milling and crushing on the grinding material. In order to control the subsequent ball milling time and the stability of the process, and to improve the stability of the grinding material ferrite tile, this application classifies and screens the grinding materials generated from rough grinding and fine grinding. This can prevent the grinding materials generated from rough grinding and fine grinding from using the same ball milling process without distinction, resulting in two peaks in the particle size distribution curve or the normal distribution curve being flattened. One is that during the pressing of the orientation forming, the particles cannot rotate, the anisotropy of the green compact is poor, and the magnetic energy product decreases. The other is that after sintering, the grain growth sizes vary greatly, seriously affecting the magnetic properties. Larger grains will reduce the remanence and coercivity of the ferrite tile, and smaller grains will generate more paramagnetic phases, reducing the magnetic properties.

[0038] Step Three: Drying

[0039] Respectively introduce the coarse grinding material and the fine grinding material obtained from the screening in Step Two into a drum dryer. The drum dryer is 6 m long, with an inclination angle of 30°. The inlet is 1 m higher than the outlet. There is an exhaust opening at the inlet, and there is a dust removal device above the exhaust opening. Inside the drum dryer, there are guide steel sheets welded. When rotating forward, the guide steel sheets make the material move towards the outlet, and when rotating in reverse, the material also moves towards the outlet. Control the heating temperature of the drum dryer at 180 - 220 °C, the rotation speed at 5 r / min, and control the forward and reverse rotations to alternate in sequence for 30 - 40 min. In this way, the dried coarse grinding material and the dried fine grinding material can be obtained.

[0040] After passing through the drum dryer, the moisture content of the ground material is measured to be 2 - 5% after drying.

[0041] The purpose of using the drum dryer to dry the ground material is as follows:

[0042] 1. Rotary drying makes the ground material evenly heated, ensuring that the moisture content of the dried ground material is uniform and stable.

[0043] 2. On the premise of stable moisture content, the proportion can be strictly controlled in the later ball milling process to ensure the accuracy of the additive addition amount.

[0044] When the moisture content in the ground material is inaccurate, it has the following effects on the ferrite magnetic tile:

[0045] When the ratio of water to balls is too large, it may cause the particle size of the ground material to be too small during ball milling, difficult drainage during wet forming, poor forming degree, and easy chipping, cracking, and breaking. When the ratio of water to balls is too small, the ball milling time will be prolonged, the production efficiency will be reduced, and even the particle size of the ground material after ball milling will be too large, the crystal grains will be too large, and the magnetic properties will be reduced. If the ground material is not dried and the moisture content measurement is inaccurate, it will have a great impact on the additive addition amount. The additives are rare earth lanthanum, cobalt, chromium compounds, etc., and the addition amount is 1wt% - 5%, and the additives play a crucial role in remanence, coercivity, and magnetic energy product.

[0046] Therefore, by adding the drum dryer, we can not only control the moisture content of the ground material, solve the existing problems of precipitation and drying of the ground material, ensure the production environment, shorten the utilization cycle of the ground material, improve the production efficiency of the company, but also further ensure the accuracy of the additive addition amount.

[0047] Step Four: Ball Milling

[0048] Add the ground material, water, and steel balls into the ball mill tank according to the weight ratio of (0.8 - 1.2):(1.3 - 1.7):(5 - 7); among them, the weight ratio of the dried coarse ground material and fine ground material in the ground material is (7 - 9):(3 - 1); the steel ball diameters are 6mm, 8mm, 10mm, and ensure that the total surface areas of the three added are equal, the ball milling speed is 40 - 50r / min, and after ball milling for 8 - 12h, add a certain proportion of additives according to the total weight of the ground material;

[0049] The additive described is CaCO 3 、La 2 0 3 or Cr 2 O 3 , which is a commonly used additive in this field, and the additive used in this application can be the same as the additive used in the application with the application number 201410444633.1.

[0050] The purposes of this process are as follows:

[0051] 1. Fine grinding of the coarse grinding material. The grinding material is generated by grinding and cutting the magnetic tile with a grinding wheel with emery during the grinding process. Since the hardness of the permanent magnet strontium ferrite is about 500 HV, when the magnetic tile first contacts the grinding wheel, the grinding material almost falls off brittlely, with a relatively large particle size and sharp corners in the particle morphology.

[0052] 2. We preferably add the additive after ball milling for 8 - 12 h. At this time, the morphology and particle size of the coarse and fine grinding materials after ball milling are basically stable, and adding the additive has the most obvious improvement on the magnetic properties of the ferrite magnetic tile. The reasons are as follows: When the surface morphology of the particles is uneven and the sharp corners of the surface morphology of the grinding material are prominent, there will be a strong adsorption and bonding effect. If the additive and the grinding material are added together into the ball milling tank, the uniformity of the mixture cannot be guaranteed. We optimized to first ball mill the grinding material for 18 - 12 h to control the particle morphology to be close to a spherical shape, and then add a certain proportion of the additive to ensure the uniform mixing of the additive and the dried magnetic powder. During the ball milling process, the grinding material and the additive are continuously extruded and strongly impacted, generating a large amount of heat energy, which in turn causes diffusion and solid-phase reactions of the sample, and ion substitution and replacement continue to occur during the subsequent sintering, improving the magnetic properties. During sintering, some low-melting-point additives (CaCO 3 ) will also play a role in improving the magnetic properties of the ferrite magnetic tile at the grain boundaries.

[0053] 3. The addition of the additive improves the magnetic properties of the grinding material. The rare earth element La 3+ has special electronic structures, low crystal symmetry, and magnetic ions in the inner shell layer, etc., which cause the electrostatic field interaction and spin-orbit interaction, resulting in its relatively high atomic magnetic moment, magnetocrystalline anisotropy, and magnetostriction coefficient. La 2 O 3 in La 3+ can partially replace Sr 2+ in the permanent magnet strontium ferrite, can stabilize the crystal structure, improve the magnetic properties of the grinding material, make up for the crystal defects existing in the grinding material, and prevent the problem of insufficient performance caused by the repeated use of the grinding material. The grinding material used once or multiple times will have a decrease in the intrinsic coercivity due to the increase in crystal defects and the accumulation of small-particle ferrite dust. According to the reverse magnetization domain nucleation theory, the particle morphology of the grinding material has difficulty rotating during the orientation forming process, and the magnetocrystalline anisotropy is uneven. When the small particles in the grinding material increase, the demagnetization coupling effect will increase. The ionic radii of the 3d transition metal elements Cr 3+ and Fe 3+ are similar. After substitution, it will increase the critical size of the ferrite single domain and improve the intrinsic coercivity.

[0054] Step Five: Particle Size Control;

[0055] During the process of Step 4, a laser particle size analyzer is used to analyze the particle size of the ground material after ball milling. When the particle size D90 of the ground material after ball milling is ≤ 0.85 μm, D50 is between 0.72 - 0.76 μm, and D10 ≥ 0.68 μm, the ball mill tank is closed;

[0056] The single-domain critical size of permanent magnet strontium ferrite is around 0.95 - 1.15 μm. Considering the grain growth behavior during the sintering process, the D50 particle size of the ground powder including coarse and fine materials after ball milling should be controlled between 0.7 - 0.8 μm. If the ball milling time is too long or the ball-to-material ratio is large, the average particle size of the powder will be small and the particle size distribution of the ground material will be broadened, resulting in more paramagnetic phases and reducing the magnetic properties of the sintered body. At the same time, during magnetic field forming, if the average particle size of the powder is too small, it is difficult to discharge the moisture in the powder, affecting the pressing effect of the sample. If the ball milling time is too short or the ball-to-material ratio is small, the average particle size of the powder will be too large, the powder activity will not be high, resulting in too large grain size of the sample after sintering, affecting the coercivity and remanence of the material. Therefore, to ensure that the dried magnetic powder after secondary grinding has good dispersibility, a narrow particle size distribution, is suitable for magnetic field forming, and has excellent magnetic properties after sintering.

[0057] Step 6: Sedimentation;

[0058] After the ground material goes through Step 4 and Step 5, the ground material in the ball mill tank is pumped into the sedimentation tower by a material suction device. After standing for 12 - 18 h, the ground material moves towards the bottom of the sedimentation tower under the action of gravity. At this time, the water in the upper part of the sedimentation tower is extracted, and the moisture content of the ground material in the sedimentation tower is controlled between 27 - 37%, obtaining a ground slurry.

[0059] Step 7: Pressing and sintering;

[0060] Wet orientation pressing forming: There is a discharge port at the lower part of the sedimentation tower in Step 6. Take the ground slurry and pour it into the press hopper. The press closes the mold, injects the ground slurry, starts the orientation magnetic field, the particles of the ground slurry rotate uniformly, the lower punch of the press moves, the moisture is discharged, and the ground slurry forms a certain shape, and finally pressure holding is carried out; Subsequently, the orientation magnetic field is 2.0 - 2.4 T, the duration is 15 - 20 s, and the mold closing and pressure holding time is 15 - 20 s, obtaining a pressed blank.

[0061] Place the pressed blank on a mesh belt sintering furnace. The highest sintering temperature is between 1160 - 1200 °C. The setting of this temperature zone is considered as follows: Since the ground material is recycled and reused material, additives (CaCO 3 , HBO 3 and SiO 2) During sintering, silicate substances are inevitably produced. When these substances are recycled, reused, and sintered again, they will first form a liquid phase, creating a fast channel for crystal diffusion, accelerating the formation of ferrite crystals and the diffusion of grain boundaries. Therefore, if the temperature is too high, the grains will grow abnormally, reducing the coercivity; if the temperature is too low, the liquid-phase sintering will not be complete, resulting in a decrease in the density, magnetic properties, and mechanical properties of the ferrite magnetic tile.

[0062] To verify the feasibility of this application, this application specifically applied this method to the permanent magnet strontium ferrite grinding material, and the obtained blank samples were tested. The test results are as follows: Br≥3800 Gs, Hcb≥3750 Oe, Hcj≥4750 Oe, (BH)max is between 2.8 - 3.6 MGOe; it can be clearly concluded from the above results that the products produced by this method have good quality, and the obtained blank samples can meet the requirements of subsequent production and use.

[0063] The permanent magnet strontium ferrite magnetic tile is a functional material with a wide hysteresis loop, high coercivity, high remanence, low cost, and can maintain a constant magnetism once magnetized, and has been widely used in new energy drive motors and generators. This application not only solves the problem of the recycling and utilization of permanent magnet strontium ferrite grinding material, but also ensures the performance of the magnetic tile, controls the production process cost of ferrite raw materials, improves the market competitiveness of ferrite magnetic tile products, indirectly reduces the cost problem of the downstream new energy host market, enables the permanent magnet strontium ferrite magnetic tile to be more widely used in the new energy field, and becomes an important part of energy conservation, emission reduction, and carbon emission reduction.

[0064] The recycling method of this permanent magnet strontium ferrite grinding material recycles the permanent magnet strontium ferrite grinding material through steps such as dispersion, drying, and ball milling using a practical ultrasonic oscillation sieve machine, thus solving the problems of large impurity components, poor quality control of recycled materials, environmental pollution, and poor quality of the obtained finished products existing in the existing recycling methods of permanent magnet strontium ferrite grinding material, and is particularly suitable for the production needs of enterprises.

Claims

1. A method for recycling permanent magnet strontium ferrite grinding materials, characterized in that: The recycling method includes the following steps: Step 1: Precipitation recycling; Step 2: Oscillation sieving; Step 3: Drying Feed the coarse grinding materials and fine grinding materials obtained by sieving in Step 2 into a drum dryer respectively. The drum dryer is 6 m long, with an inclination angle of 30°, the feed inlet is 1 m higher than the discharge outlet, there is an exhaust opening at the feed inlet, and there is a dust removal device above the exhaust outlet. Inside the drum dryer, there are guide steel sheets welded. When rotating forward, the guide steel sheets make the materials move towards the discharge outlet, and when rotating in reverse, the materials also move towards the discharge outlet. Control the heating temperature of the drum dryer at 180 - 220 °C, the rotation speed at 5 r / min, and control the forward and reverse rotations to alternate in sequence for 30 - 40 min. In this way, the dried coarse grinding materials and dried fine grinding materials can be obtained; Step 4: Ball milling Step 5: Particle size control; During the process of Step 4, use a laser particle size analyzer to analyze the particle size of the grinding materials after ball milling. When the particle size D90 of the ball-milled grinding materials ≤ 0.85 μm, D50 is between 0.72 - 0.76 μm, and D10 ≥ 0.68 μm, close the ball milling tank; Step 6: Sedimentation; After the grinding materials go through Step 4 and Step 5, use a suction device to pump the grinding materials in the ball milling tank into the sedimentation tower. After standing for 12 - 18 h, the grinding materials move towards the bottom of the sedimentation tower under the action of gravity. At this time, extract the water in the upper part of the sedimentation tower, and control the moisture content of the grinding materials in the sedimentation tower to be between 27 - 37% to obtain grinding slurry; Step 7: Pressing and sintering; Wet orientation pressing and forming: There is a discharge outlet at the lower part of the sedimentation tower in Step 6. Take the grinding slurry and pour it into the press hopper. The press closes the mold, injects the grinding slurry, starts the orientation magnetic field, and the particles of the grinding slurry rotate uniformly. The lower punch of the press moves, the water is discharged, and the grinding slurry forms a certain shape. Finally, keep the pressure; Subsequently, the orientation magnetic field is 2.0 - 2.4 T, the duration is 15 - 20 s, and the mold closing and pressure maintaining time is 15 - 20 s to obtain a pressed blank.

2. A method for recycling permanent magnet strontium ferrite grinding materials according to claim 1, characterized in that: The specific process of Step 1 is as follows: Collect the grinding materials generated during the grinding process of permanent magnet strontium ferrite. The grinding materials are collected together with the cooling water into the precipitation tower. After the grinding materials stand in the precipitation tower for a period of time, recycle them.

3. A method for recycling permanent magnet strontium ferrite grinding materials according to claim 1, characterized in that: The specific process of Step 2 is as follows: Use an ultrasonic oscillation sieving machine to oscillate and screen the recycled grinding materials in Step 1 for 30 - 40 min using 120 mesh and 300 mesh sieving meshes under the action of ultrasonic waves; Remove the oversize materials on the surface of the 120 mesh sieving mesh as impurities, recycle the oversize materials on the surface of the 300 mesh sieving mesh as coarse grinding materials, and recycle the materials on the lower surface of the 300 mesh sieving mesh as fine grinding materials.

4. A method for recycling permanent magnet strontium ferrite grinding materials according to claim 1, characterized in that: The specific process of the fourth step is as follows: abrasive, water and steel balls are added into the ball mill according to the weight ratio of (0.8-1.2):(1.3-1.7):(5-7); among them, the weight ratio of the dried coarse abrasive and fine abrasive in the abrasive is (7-9):(3-1); the diameters of the steel balls are 6mm, 8mm and 10mm, and it is ensured that the total surface areas of the three added are equal, the ball milling speed is 40-50 r / min, and after ball milling for 8-12 h, an additive is added according to a certain proportion of the total weight of the abrasive.

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