A high-abundance rare earth iron boron regeneration magnet and its preparation method

Abstract

A high-abundance rare earth iron boron regenerated magnet and its preparation method belong to the field of rare earth permanent magnet materials and their recycling technology. After surface treatment, high-abundance Ce / La rare earth iron boron unqualified products and processing waste are subjected to coarse crushing and hydrogen explosion powdering; a Ce, La, Nd, and Pr rare earth alloy is prepared using a rapid solidification belt spinning technology and hydrogen explosion; the above two materials are ball milled, mixed, oriented, and pressed according to a certain proportion, and then sintered and heat treated to obtain a regenerated sintered magnet. The regenerated magnet prepared by the present invention has a waste material utilization rate of up to 95%, a low rare earth addition amount (0 to 5wt.%), and a light rare earth addition ratio (LaCe / NdPr) greater than 50%. The coercive force of the regenerated magnet is significantly improved, and the comprehensive magnetic properties are equivalent to or even higher than those of the original magnet. The present invention can accurately control the cheap light rare earths La and Ce to obtain a high-performance regenerated magnet, thereby realizing the high-value recycling of high-abundance rare earth permanent magnets.

Description

Technical Field

[0001] The invention relates to a high-abundance rare earth iron boron regeneration magnet and a preparation method thereof, belonging to the technical field of rare earth permanent magnet materials and their recovery. Background Art

[0002] Neodymium iron boron (NdFeB) is the most widely used permanent magnet material today. With the development of society, the demand for permanent magnet materials is increasing. Traditional sintered Nd-Fe-B magnets primarily use the rare earth elements Pr and Nd. However, Pr and Nd are expensive. Therefore, large amounts of the highly abundant rare earth elements La and Ce are used to replace these currently expensive elements in the production of sintered magnets. This approach not only achieves comprehensive utilization of rare earth resources, but also reduces costs and protects the environment, which is of great significance to the sustainable development of the rare earth permanent magnet industry. However, compared to NdFeB magnets, the manufacturing process for high-abundance Ce / La rare earth iron boron is less mature. In particular, when the (Ce+La) / Re rare earth content reaches 30-50wt%, it is very easy to cause high levels of impurities in the product, substandard appearance and magnetic properties, and high scrap rates. Therefore, the recycling and reuse of waste magnets containing high-abundance rare earth elements such as La and Ce is of great significance.

[0003] At present, in addition to traditional hydrometallurgy and pyrometallurgy, the recycling method for sintered NdFeB materials is generally a high resource recycling rate and environmentally friendly regeneration method: the NdFeB recycled material is surface treated and then hydrogen exploded and air flow milled to produce magnetic powder, which is then subjected to magnetic field orientation molding, isostatic pressing, sintering and tempering to prepare blanks. In order to obtain better performance, it is necessary to add a certain proportion of NdFeB powder or rare earth nanopowders such as elemental Nd\Dy\Tb to the waste recycled powder. Because elemental rare earth nanopowders are difficult to prepare, the process cost is high and they are easily oxidized, resulting in low waste material utilization and poor consistency of recycled magnet products. More importantly, current recycling methods are mainly aimed at rare earth magnets containing large amounts of expensive elements such as Pr, Nd, Dy, and Tb. There is almost no research on the recycling of magnets with high content of light rare earth elements such as La and Ce. Since the correlation between the composition, microstructure and performance of high-content light rare earth iron boron sintered magnets is very different from that of sintered neodymium iron boron, it is urgent to develop a suitable preparation method to obtain more economical high-abundance rare earth iron boron recycled magnets. Summary of the Invention

[0004] In order to solve the above problems, the present invention first proposes a method for high-abundance Ce / La rare earth iron boron magnets (RE xMFeB, 28.5wt.%≤x≤34wt.%, RE is a rare earth element and contains at least one of Ce / La, M is one or more of Ga, Co, Cu, Nb, Al, Zr elements) short process recovery method, especially Ce or / and La element content accounts for more than 30% of the total rare earth amount. Through the short process recovery process, the surface of the waste magnet is first cleaned, and then it is subjected to hydrogen crushing, ball milling, oriented pressing, cold isostatic pressing, sintering and heat treatment to prepare the regenerated magnet. In the process of preparing the regenerated magnet, due to the serious oxidation of the original waste magnet and the loss of rare earth in the preparation process, the present invention selects the form of hydrogen explosion + ball milling to prepare rare earth element / alloy to accurately control the rare earth composition. It mainly includes the following steps:

[0005] (1) The collected high-abundance Ce / La sintered NdFeB block recycled material is subjected to surface pretreatment. The surface pretreatment is ultrasonic pickling with dilute nitric acid at a concentration of 0.01 to 0.25 mol / L for 30 to 60 seconds or mechanical polishing such as a grinding wheel machine or a polishing machine is used to remove the surface oxide layer; after the surface treatment is clean, it is coarsely crushed using a jaw crusher;

[0006] (2) Place the coarsely crushed recovered material into a hydrogen explosion furnace; hydrogen explosion parameter settings: hydrogen absorption temperature 200-260°C / 1-3h; dehydrogenation temperature 550-600°C / 3-6h. The coarsely crushed magnetic powder is subjected to hydrogen explosion treatment to obtain hydrogen explosion powder recovered material with a particle size of approximately 50-200μm;

[0007] (3) Selecting alloys or single elements of Ce, La, Pr, and Nd, polishing their surface oxide layers clean and cutting them into small pieces before placing them into a hydrogen explosion furnace. The hydrogen explosion parameters are set as follows: hydrogen absorption temperature of 100-150°C / 1-3h, and air cooling to room temperature to obtain rare earth hydrogen explosion powder;

[0008] (4) Weigh the corresponding recycled materials from step (2) and the Ce, La, Pr, Nd alloy or elemental rare earth hydrogen explosion powder from step (3) in a certain proportion and mix them and ball mill them; select five types of steel balls: φ12: 30g; φ10: 40g; φ8: 60g; φ6: 40g; φ4: 30g, and grind them under the protection of n-heptane liquid with a ball-to-material ratio of 15:1. The high-energy ball mill voltage is selected to be 70-80V, and the powder is ground for 3-6 hours to obtain a powder with a size of 2-6μm;

[0009] (5) Add 0.1-0.5wt.% of lubricant and antioxidant to the prepared regenerated ball mill powder, mix it in a mixer for 5-10 hours, and perform orientation pressing on the mixed magnetic powder. The process parameters are as follows: the orientation current is set to 60A-65A, the demagnetization current is set to 5A-10A, the pressure is set to 7.9MPa-8.9MPa, and the pressing delay is 2s. After the pressing is completed, the obtained pressed embryo is vacuum-sealed in time and placed in a hydraulic press for oil pressure. The oil pressure parameters are as follows: the pressure is selected to be 225Mpa-250Mpa, and the pressure is maintained for 180s-240s. After the oil pressure is completed, it is sealed and placed in a sintering furnace and sintered at 1040℃-1060℃ for 2h-4h.

[0010] (6) performing secondary heat treatment on the sintered magnet at 800°C to 850°C for 2h to 4h and then at 400°C to 450°C for 2h to 4h, and finally obtaining a regenerated NdFeB magnet;

[0011] The amount of Ce, La, Pr, Nd alloy or single rare earth hydrogen explosion powder added in step (4) is 0-5wt.%, and the specific amount of Ce, La, Pr, Nd added is added according to the composition requirements of the regenerated NdFeB magnet in step (6).

[0012] The present invention has the following advantages:

[0013] (1) A short-process recycling process is adopted for waste NdFeB magnets with high abundance of La and Ce, which effectively avoids the disadvantages of traditional methods such as chemical extraction and synthesis, such as long process, complicated process and pollution to the environment.

[0014] (2) The powder making process adopts hydrogen explosion + ball milling process, which can effectively shorten the magnet preparation process and prepare magnetic powder with uniform particle size.

[0015] (3) When ball milling, different ball sizes and proportions are selected, and n-heptane liquid is used as an auxiliary protection. While ensuring the ball milling effect, the ball milling time can be effectively reduced and oxidation can be reduced.

[0016] (4) The present invention regulates the composition of the regenerated magnet by adding a variety of rare earth elements / alloys. By adding a small amount of rare earth, especially a small amount of cheap light rare earth La and Ce, a high-performance regenerated magnet can be obtained, and the composition of the regenerated magnet can be precisely regulated, effectively avoiding the waste of rare earth resources and other elements, and being more efficient and environmentally friendly.

[0017] (5) This method has a high waste recovery rate and excellent performance of the regenerated magnets. The waste utilization rate is as high as 95%, the rare earth addition amount is low (0-5wt.%), and the added light rare earth addition ratio (LaCe / NdPr ratio) is greater than or equal to 50%. The coercive force of the regenerated magnet is significantly improved, and the comprehensive magnetic properties are equivalent to or even higher than those of the original magnet. DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples.

[0019] A high-abundance rare earth iron boron regeneration magnet and its preparation method, the specific implementation method is as follows:

[0020] Example 1:

[0021] (1) A batch of high-abundance La and Ce waste NdFeB magnets were recycled. The total rare earth content of the magnets was 31.9wt.%, of which Pr+Nd elements accounted for 19.1wt.%, La+Ce elements accounted for 12.8wt.%, and La+Ce elements accounted for about 40% of the total rare earth content. The waste size was 15*10*8mm.

[0022] (2) The waste magnets were polished with a grinding wheel to remove the surface oxide layer for 3 minutes, and the polished magnets were vacuum stored in sealed bags.

[0023] (3) Surface treatment: The clean magnets are mechanically crushed using a jaw crusher under argon protection, and the crushed magnet blocks are vacuum stored in sealed bags.

[0024] (4) The small pieces of magnets after mechanical coarse crushing in step 3 are placed in a hydrogen explosion furnace for hydrogen explosion treatment. The hydrogen explosion parameters are set as a hydrogen absorption temperature of 260°C / 3h and a dehydrogenation temperature of 550°C / 3h. After the reaction is complete, hydrogen explosion powder is obtained.

[0025] (5) Select Ce, La rare earth elements, PrNd alloy (preferably Pr 0.25 Nd 0.75 ), clean the surface oxide layer, cut it into small pieces and put it into the hydrogen explosion furnace. The hydrogen explosion parameters are set as follows: hydrogen absorption temperature 150℃ / 3h, air cooling to room temperature to obtain rare earth hydrogen explosion powder.

[0026] (6) Recycled magnetic powder was not added with any rare earth supplements. The corresponding recycled hydrogen explosion powder was weighed and ball milled. Five types of steel balls (φ12: 30g; φ10: 40g; φ8: 60g; φ6: 40g; and φ4: 30g) were selected. The ball-to-material ratio was 15:1 and the powder was milled under the protection of n-heptane liquid. The high-energy ball milling voltage was selected to be 75V, and the powder was milled for 5 hours to obtain a ball-milled powder of approximately 3μm.

[0027] (7) Add 0.1wt.% lubricant and 0.2wt.% antioxidant to the prepared regenerated magnetic powder, mix it in a mixer for 10 hours, and perform orientation pressing on the mixed magnetic powder. The process parameters are as follows: orientation current is set to 60A, demagnetization current is set to 8A, pressure is set to 7.9MPa, and pressing delay is 2s. After the pressing is completed, the obtained pressed embryo is vacuum-sealed in time and placed in a hydraulic press for oil pressure. The oil pressure parameters are as follows: pressure is selected to 225MPa and pressure is maintained for 180s. After the oil pressure is completed, it is sealed and placed in a sintering furnace and sintered at 1050℃ for 3 hours.

[0028] (8) The sintered magnet is subjected to a two-stage heat treatment by sequentially performing heat treatment at 820°C for 3 h and at 420°C for 3 h, and finally a regenerated NdFeB magnet is obtained, which is designated as magnet Q.

[0029] ICP test was performed on the regenerated NdFeB magnet Q. The results showed that the total rare earth content was 29.59wt.%, of which Pr+Nd elements accounted for 18.74wt.%, La+Ce elements accounted for 10.85wt.%, and La+Ce elements accounted for about 36.66% of the total rare earth content. From the ICP test results, it can be seen that the total rare earth content was lost by 2.31wt.%, La+Ce lost by 1.95wt.%, and Pr+Nd lost by 0.36wt.%.

[0030] Example 2:

[0031] The difference from Example 1 is that according to the ICP test results of the regenerated magnet in Example 1, 1.95wt.% La+Ce (preferably 1:9) is added to the recycled magnetic powder. 0.25 Nd 0.75 The nominal composition of the original magnet can be achieved by adding 0.36wt.% of alloy. 0.25 Nd 0.75 The hydrogen-exploded powder was ball-milled. Five types of steel balls (φ12: 30g; φ10: 40g; φ8: 60g; φ6: 40g; and φ4: 30g) were selected, with a ball-to-bearing ratio of 15:1, and milled under n-heptane liquid. The high-energy milling voltage was set at 75V, and the milling was performed for 5 hours, resulting in a ball-milled powder approximately 3μm in size. The milled regenerated magnetic powder was then added with 0.1wt.% lubricant and 0.2wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing and cold isostatic pressing. The powder was then placed in a sintering furnace and sintered at 1050°C for 3 hours. The resulting regenerated NdFeB magnet was then heat-treated at 820°C for 3 hours and at 420°C for 3 hours. This was designated as magnet T.

[0032] Example 3:

[0033] The difference from Example 2 is that: on the basis of the magnet T component, La+Ce is further added with 0.5wt.%, Pr 0.25 Nd 0.75 Add 0.5wt.%, weigh the corresponding recycled materials, Ce, La, Pr 0.25 Nd 0.75 The hydrogen-exploded powder is ball-milled. The milled regenerated magnetic powder is then added with 0.1 wt.% lubricant and 0.2 wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing and cold isostatic pressing. The powder is then placed in a sintering furnace and sintered at 1040°C for 3 hours, followed by a primary heat treatment at 820°C for 3 hours and a secondary heat treatment at 420°C for 3 hours to obtain regenerated NdFeB magnets.

[0034] Example 4:

[0035] The difference from Example 2 is that 1 wt.% of La+Ce is added to the T component of the magnet, and the corresponding recycled materials, Ce, and La hydrogen explosion powder are weighed and ball-milled. The regenerated magnetic powder after ball milling is added with 0.1 wt.% of lubricant and 0.2 wt.% of antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing, cold isostatic pressing, and then placed in a sintering furnace and sintered at 1030°C for 3 hours. The sintering time is then sintered at 820°C / 3 hours in a primary heat treatment and 420°C / 3 hours in a secondary heat treatment to obtain a regenerated NdFeB magnet.

[0036] Example 5:

[0037] The difference from Example 2 is that: 1wt.% La+Ce is added to the magnet T component. 0.25 Nd 0.75 Add 1wt.%, weigh the corresponding recycled materials, Ce, La, Pr 0.25 Nd 0.75 The hydrogen-exploded powder is ball-milled. The milled regenerated magnetic powder is then added with 0.1 wt.% lubricant and 0.2 wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing and cold isostatic pressing. The powder is then placed in a sintering furnace and sintered at 1040°C for 3 hours, followed by a primary heat treatment at 830°C for 3 hours and a secondary heat treatment at 430°C for 3 hours to obtain regenerated NdFeB magnets.

[0038] Example 6:

[0039] The difference from Example 2 is that: according to the ICP test results of Example 1, the total rare earth loss is 2.31wt.%, of which La+Ce loss is 1.95wt.%, and Pr+Nd loss is 0.36wt.%. At this time, the (La+Ce): (Pr+Nd) ratio is about 5.4:1. Keeping the total rare earth content unchanged, the magnetic properties of the regenerated magnet are explored by adjusting the ratio of (La+Ce) to (Pr+Nd). That is, the ratio of the two is first set to 3:1, that is, 1.73wt.% of La+Ce and 0.36wt.% of Pr+Nd are added to the recycled magnetic powder. 0.25 Nd 0.75 Adding 0.58wt.% can reach the total amount of rare earth in the original magnet. Weigh the corresponding recycled materials, Ce, La, Pr 0.25 Nd 0.75 The hydrogen-exploded powder was ball-milled. Five types of steel balls (φ12, 30g; φ10, 40g; φ8, 60g; φ6, 40g; and φ4, 30g) were selected, with a ball-to-material ratio of 15:1, and milled under n-heptane liquid. The high-energy milling voltage was selected at 75V, and the milling was performed for 5 hours, resulting in a ball-milled powder approximately 3μm in size. The milled regenerated magnetic powder was then added with 0.1wt.% lubricant and 0.2wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing and cold isostatic pressing. The powder was then placed in a sintering furnace and sintered at 1060°C for 3 hours. The resulting regenerated NdFeB magnets were then subjected to a primary heat treatment at 820°C for 3 hours and a secondary heat treatment at 420°C for 3 hours.

[0040] Example 7:

[0041] The difference from Example 6 is that the ratio of (La+Ce):(Pr+Nd) is 2:1, that is, 1.54wt.% La+Ce and 1.54wt.% Pr are added to the recycled magnetic powder. 0.25 Nd 0.75 Adding 0.77wt.% can reach the total amount of rare earth in the original magnet. Weigh the corresponding recycled materials, Ce, La, Pr 0.25 Nd 0.75 The hydrogen-exploded powder was ball-milled. Five types of steel balls (φ12, 30g; φ10, 40g; φ8, 60g; φ6, 40g; and φ4, 30g) were selected, with a ball-to-material ratio of 15:1, and milled under n-heptane liquid. A high-energy ball milling voltage of 75V was used for 5 hours, resulting in a ball-milled powder approximately 3μm in size. The milled regenerated magnetic powder was then added with 0.1wt.% lubricant and 0.2wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing. After cold isostatic pressing, the powder was placed in a sintering furnace and sintered at 1050°C for 3 hours. The resulting regenerated NdFeB magnets were then subjected to a primary heat treatment at 820°C for 3 hours and a secondary heat treatment at 420°C for 3 hours.

[0042] Example 8:

[0043] The difference from Example 6 is that the ratio of (La+Ce):(Pr+Nd) is 1:1, that is, 1.16wt.% La+Ce and 1.16wt.% Pr are added to the recycled magnetic powder. 0.25 Nd 0.75 Adding 1.16wt.% can reach the total amount of rare earth in the original magnet. Weigh the corresponding recycled materials, Ce, La, Pr 0.25 Nd 0.75 The hydrogen-exploded powder was ball-milled. Five steel balls (φ12, 30g; φ10, 40g; φ8, 60g; φ6, 40g; and φ4, 30g) were selected, with a ball-to-material ratio of 15:1, and milled under n-heptane liquid. The high-energy milling voltage was 75V, and the milling was performed for 5 hours, resulting in a ball-milled powder approximately 3μm in size. The milled regenerated magnetic powder was then added with 0.1wt.% lubricant and 0.2wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing. After cold isostatic pressing, the powder was placed in a sintering furnace and sintered at 1040°C for 3 hours. The resulting regenerated NdFeB magnets were then subjected to a primary heat treatment at 820°C for 3 hours and a secondary heat treatment at 420°C for 3 hours.

[0044] Example 9:

[0045] (1) A batch of high-abundance La and Ce waste NdFeB magnets were recycled, of which Pr+Nd elements accounted for 25.52wt.%, Ce elements accounted for 4.52wt.%, and no La element was contained. Ce elements accounted for 15% of the total rare earth elements. The waste size was 18*12*6mm.

[0046] (2) The waste magnets were polished with a grinding wheel to remove the surface oxide layer for 3 minutes, and the polished magnets were vacuum stored in sealed bags.

[0047] (3) Surface treatment: The clean magnets are mechanically crushed using a jaw crusher under argon protection, and the crushed magnet blocks are vacuum stored in sealed bags.

[0048] (4) The small pieces of magnets after mechanical coarse crushing in step 3 are placed in a hydrogen explosion furnace for hydrogen explosion treatment. The hydrogen explosion parameters are set as a hydrogen absorption temperature of 260°C / 3h and a dehydrogenation temperature of 550°C / 3h. After the reaction is complete, hydrogen explosion powder is obtained.

[0049] (5) Select Ce element, PrNd alloy (preferably Pr 0.25 Nd 0.75 ), clean the surface oxide layer, cut it into small pieces and put it into the hydrogen explosion furnace. The hydrogen explosion parameters are set as follows: hydrogen absorption temperature 150℃ / 3h, air cooling to room temperature to obtain rare earth hydrogen explosion powder.

[0050] (6) Recycled magnetic powder was not added with any rare earth supplements. The corresponding recycled hydrogen explosion powder was weighed and ball milled. Five types of steel balls (φ12: 30g; φ10: 40g; φ8: 60g; φ6: 40g; and φ4: 30g) were selected. The ball-to-material ratio was 15:1 and the powder was milled under the protection of n-heptane liquid. The high-energy ball mill voltage was selected to be 75V, and the powder was milled for 5.5 hours to obtain a ball-milled powder of approximately 2μm.

[0051] (7) Add 0.1wt.% lubricant and 0.2wt.% antioxidant to the prepared regenerated magnetic powder, mix it in a mixer for 10 hours, and perform orientation pressing on the mixed magnetic powder. The process parameters are as follows: orientation current is set to 60A, demagnetization current is set to 8A, pressure is set to 7.9MPa, and pressing delay is 2s. After the pressing is completed, the obtained pressed embryo is vacuum-sealed in time and placed in a hydraulic press for oil pressure. The oil pressure parameters are as follows: pressure is selected to 225MPa and pressure is maintained for 180s. After the oil pressure is completed, it is sealed and placed in a sintering furnace and sintered at 1090℃ for 3 hours.

[0052] (8) The sintered magnet is subjected to a two-stage heat treatment, which is performed at 850°C for 3 hours and then at 450°C for 3 hours, to obtain a regenerated NdFeB magnet, which is designated as magnet P.

[0053] ICP test was performed on the regenerated NdFeB magnet P, and the results showed that Pr+Nd elements accounted for 25.04wt.%, La+Ce elements accounted for 3.96wt.%, and La+Ce elements accounted for 13.66% of the total rare earth elements. From the ICP test results, it can be seen that the total rare earth loss was 1.04wt.%, Ce loss was 0.56wt.%, and Pr+Nd loss was 0.48wt.%.

[0054] Example 10:

[0055] The difference from Example 9 is that: Ce is added 0.56wt.% based on the P component of the magnet. 0.25 Nd 0.75 Add 0.48wt.%, weigh the corresponding recycled materials, Ce, Pr 0.25 Nd 0.75 The hydrogen-exploded powder was ball-milled. 0.1 wt.% lubricant and 0.2 wt.% antioxidant were added to the ball-milled regenerated magnetic powder and mixed in a mixer for 10 hours. Oriented pressing and cold isostatic pressing were then performed in a sintering furnace and sintered at 1080°C for 3 hours. The powder was then subjected to a primary heat treatment at 850°C for 3 hours and a secondary heat treatment at 450°C for 3 hours to obtain a regenerated NdFeB magnet, designated as Magnet M.

[0056] Example 11:

[0057] The difference from Example 10 is that: 0.5wt.% Ce is added to the magnet M component, and Pr 0.25 Nd 0.75 Add 0.5wt.%, weigh the corresponding recycled materials, Ce, Pr 0.25 Nd 0.75 The hydrogen-exploded powder is ball-milled. The milled regenerated magnetic powder is then added with 0.1 wt.% lubricant and 0.2 wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing and cold isostatic pressing. The powder is then placed in a sintering furnace and sintered at 1070°C for 3 hours. The powder undergoes a primary heat treatment at 850°C for 3 hours and a secondary heat treatment at 450°C for 3 hours to obtain regenerated NdFeB magnets.

[0058] Example 12:

[0059] The difference from Example 10 is that 1 wt.% of Ce is added to the magnet M component, and the corresponding recycled material and Ce elemental hydrogen explosion powder are weighed and ball-milled. The regenerated magnetic powder after ball milling is added with 0.1 wt.% of lubricant and 0.2 wt.% of antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing, cold isostatic pressing, and then placed in a sintering furnace and sintered at 1060°C for 3 hours. The sintering time is 3 hours, and the primary heat treatment is 850°C / 3 hours, and the secondary heat treatment is 450°C / 3 hours to obtain a regenerated NdFeB magnet.

[0060] Example 13:

[0061] The difference from Example 10 is that: 1wt.% of Ce is added to the magnet M component. 0.25 Nd 0.75 Add 1wt.%, weigh the corresponding recycled materials, Ce, Pr 0.25 Nd 0.75 The hydrogen-exploded powder is ball-milled. The milled regenerated magnetic powder is then added with 0.1 wt.% lubricant and 0.2 wt.% antioxidant, mixed in a mixer for 10 hours, and then subjected to orientation pressing and cold isostatic pressing. The powder is then placed in a sintering furnace and sintered at 1060°C for 3 hours, followed by a primary heat treatment at 850°C for 3 hours and a secondary heat treatment at 450°C for 3 hours to obtain regenerated NdFeB magnets.

[0062] The following table lists the magnetic properties of the magnets from various examples. Note: The raw magnets described in Examples 1-8 had a Br of 11.86 kG, an Hcj of 11.17 kOe, and a (BH)max of 32.92 MGOe. The raw magnets described in Examples 9-13 had a Br of 12.60 kG, an Hcj of 12.36 kOe, and a (BH)max of 39.31 MGOe.

[0063]

[0064]

Claims

1. A method for preparing a high-abundance rare earth iron boron regeneration magnet, characterized in that: The following steps are involved: (1) Surface pretreatment of the collected high-abundance Ce / La sintered NdFeB block recycling materials; (2) The coarsely crushed recovered material is placed in a hydrogen explosion furnace; the hydrogen explosion parameters are set as follows: hydrogen absorption temperature 200-260°C, hydrogen absorption time 1-3 h; dehydrogenation temperature 550-600°C, dehydrogenation time 3-6 h; the coarsely crushed magnetic powder is subjected to hydrogen explosion treatment to obtain hydrogen explosion powder recovered material with a particle size of 50-200 μm; (3) Select an alloy or single element of Ce, La, Pr and Nd, polish its surface oxide layer clean and cut it into small pieces and put it into a hydrogen explosion furnace. The hydrogen explosion parameters are set as follows: hydrogen absorption temperature 100-150℃, hydrogen absorption time 1-3 hours, and air cooling to room temperature to obtain rare earth hydrogen explosion powder; the ratio of LaCe / NdPr is greater than or equal to 50%; (4) Weigh the corresponding recycled materials from step (2) and the alloys of Ce, La, Pr and Nd or hydrogen explosion powder of single rare earth from step (3) in a certain proportion and mix them and ball mill them; select φ12: 30 g; φ10: 40 g; Five types of steel balls (φ8: 60 g; φ6: 40 g; φ4: 30 g) were used, with a ball-to-material ratio of 15:1, and ground under the protection of n-heptane liquid. The high-energy ball milling voltage was selected at 70-80 V, and the grinding time was 3-6 hours to obtain a powder with a size of 2-6 μm. (5) Add 0.1-0.5 wt.% of lubricant and antioxidant to the prepared regenerated ball mill powder, mix it in a mixer for 5-10 h, and perform orientation pressing on the mixed magnetic powder. The process parameters are as follows: orientation current is set to 60 A-65 A, demagnetization current is set to 5 A-10 A, pressure is set to 7.9 MPa-8.9 MPa, and pressing delay is 2 s. After the pressing is completed, the obtained pressed embryo is vacuum packaged in time and placed in a hydraulic press for oil pressure. The oil pressure parameters are as follows: pressure is selected to be 225 MPa-250 MPa, and pressure is maintained for 180 s-240 s. After the oil pressure is completed, it is sealed and placed in a sintering furnace and sintered at 1040℃-1060℃ for 2 h-4 h. (6) The sintered magnet is subjected to secondary heat treatment at 800°C to 850°C for 2 h to 4 h and then at 400°C to 450°C for 2 h to 4 h, and finally a regenerated NdFeB magnet is obtained.

2. The method according to claim 1, characterized in that In step (1), the surface is pretreated by ultrasonic pickling with dilute nitric acid at a concentration of 0.01 to 0.25 mol / L for 30 to 60 s or by mechanical polishing with a grinding wheel or a grinding and polishing machine to remove the surface oxide layer; after the surface is cleaned, it is coarsely crushed with a jaw crusher.

3. The method according to claim 1, characterized in that In step (4), the amount of Ce, La, Pr, Nd alloy or single rare earth hydrogen explosion powder added is 0 to 5 wt.%, and the specific amount of Ce, La, Pr, Nd added is added according to the composition requirements of the regenerated NdFeB magnet in step (6).

4. A high-abundance rare earth iron boron regenerative magnet prepared according to the method according to any one of claims 1 to 3.

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