CN111968812A - Regeneration process of sintered neodymium iron boron waste - Google Patents

Abstract

The invention relates to the field of sintered neodymium iron boron magnets, in particular to a regeneration process of sintered neodymium iron boron waste. In the preparation process, auxiliary materials are added to the waste, and the auxiliary materials are proportioned according to at least one of RLxMyBzFe100‑x‑y‑z, RHaNbBcFe100‑a‑b‑c, wherein 57≤x≤70, 0≤y≤10, 0≤ z≤1; 57≤a≤70, 0≤b≤10, 0≤c≤1, RL, RH are rare earth elements, M, N are metal elements, x, y, z, a, b, c are all is the mass percentage; by adding the above-mentioned high rare earth content auxiliary materials, it can effectively make up for the deterioration of magnetic properties caused by the low rare earth content in the waste and the high oxygen and carbon content; A variety of auxiliary materials are added in different proportions to modulate the required performance. The auxiliary materials designed in the present invention have universal applicability to NdFeB wastes of different grades.

Description

A kind of regeneration process of sintered NdFeB waste

technical field

The invention relates to the field of sintered neodymium iron boron magnets, in particular to a regeneration process of sintered neodymium iron boron waste.

Background technique

As a permanent magnet material with the best comprehensive performance, sintered NdFeB materials are widely used in electronic communications, medical equipment, various motors, aerospace and military industries. According to incomplete statistics, the output of sintered NdFeB in my country in 2019 was 170,000 tons, and maintain an annual growth rate of more than 10%.

During the production and processing of NdFeB, it is inevitable that waste products, defective products, material heads, etc. will be produced. In addition, with the upgrading of electronic communication equipment, automobiles, wind turbines, etc., a large amount of NdFeB waste will be produced. Rare earth is a non-renewable strategic resource, and how to fully recycle it has become the research focus of the NdFeB industry.

In the prior art, there is no effective recovery or regeneration method for NdFeB waste. For example, a waste treatment method is introduced in Chinese Invention Patent 201710880564.2. To normal powder, the processing ratio is low and the efficiency is low. Chinese invention patent 201410068662.2 introduces a method for regenerating NdFeB waste. Using this method to treat each grade of waste requires redesigning and adding compensation components, which are not universally applicable.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a process for efficiently treating NdFeB waste and having universal applicability for different NdFeB wastes in view of the above-mentioned problems in the prior art.

The above-mentioned object of the present invention can be realized by the following technical solutions: a sintered neodymium iron boron waste regeneration process, the process comprises the following steps:

S1. NdFeB waste pretreatment: remove the oxide layer and oil stain on the surface of the waste, and then crush the waste to particles with a particle size of less than 25mm;

S2. Preparation of auxiliary materials: Weigh the auxiliary materials and carry out vacuum smelting at 1400-1480 ° C. After quick quenching, they are cooled and thrown out to make alloy thin strips; the ingredients are based on RL _{x My B z Fe 100-xyz} , RH _a N _b B At least one of _c Fe _100-abc is matched, wherein 57≤x≤70, 0≤y≤10, 0≤z≤1; 57≤a≤70, 0≤b≤10, 0≤c≤1 , RL, RH are rare earth elements, M, N are metal elements, x, y, z, a, b, c are mass percentages;

S3. Hydrogen crushing: place the pretreated waste and alloy thin strips that account for 0.5-5% of the total weight of the waste in a hydrogen crushing furnace, and crush to obtain coarse powder;

S4, jet mill: mix the coarse powder with the antioxidant which accounts for 0.2-0.8‰ of the total weight of the coarse powder, and then grind it into fine powder by jet mill;

S5. Mixing powder: mix and stir the fine powder with the antioxidant of 0.3-0.8‰ of the total weight of the fine powder and the gasoline of 3-8‰;

S6. Forming and sintering: the mixed fine powder is pressed and formed, densified and then sintered.

If the waste of the present invention is not cleaned cleanly, it will lead to internal defects of the product, deterioration of performance, and even oxidative scrapping. The pretreated waste can replace the pure metal or alloy raw materials used in the preparation of NdFeB magnetic materials in the normal process, improve the magnetic properties of the product and the replacement rate of metal raw materials, reduce the production cost and improve the utilization rate of waste resources. By adding auxiliary materials with high rare earth content, it can effectively make up for the deterioration of magnetic properties caused by low rare earth content and high oxygen and carbon content in the waste. Different ratios are added to modulate the required properties, and the auxiliary materials designed by the present invention have universal applicability to NdFeB wastes of different grades.

Preferably, in the step S2, in RL _{x My B z Fe 100-xyz} , RL is at least one of La, Ce, Pr, Nd, Pm, Sm, Eu, and M is Al, Cu, Co, Ga, At least one of Zr, Nb, and V; in the RH _a N _b B _c Fe _100-abc , RH is at least one of Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc, N is one or more of Al, Cu, Co, Ga, Zr, Nb, and V.

Preferably, the thickness of the alloy thin strip in the step S2 is 0.2-0.4 mm. The alloy ribbon in this thickness range is uniform in composition and in good crystalline state.

Preferably, the specific process of hydrogen crushing in the step S3 is as follows: first vacuumize, stop vacuuming when the degree of vacuum reaches below 2Pa, fill hydrogen to make the pressure reach 0.1-0.2Mpa, and cool the furnace body by spraying cooling water , when the hydrogen absorption is saturated, vacuumize and heat the furnace body for dehydrogenation.

Preferably, the process parameters of the jet mill in the step S4 are: the amount of oxygen added is 0, the grinding pressure is 0.45-0.65Mpa, and the rotation speed of the sorting wheel is 2800-3100rpm. Considering the high oxygen content of the waste itself, the jet mill is selected without additional oxygen. In order to obtain fine powder with uniform average particle size, the jet mill process is controlled within the above range.

Preferably, the average particle size of the specific surface area of the fine powder in the step S4 is 2.8-3.5 μm.

Preferably, the magnetic field strength of the compression molding in the step S6 is greater than or equal to 1.7T, and the maximum pressure of isostatic pressing is higher than 180MPa for densification. The above-mentioned magnetic field strength can ensure the consistency of the orientation of the reclaimed material, and the above-mentioned isostatic pressing can ensure the compactness of the reclaimed material, so as to finally obtain the reclaimed material with good magnetic properties.

Preferably, the sintering in the step S6 includes high-temperature sintering, primary aging, and secondary aging; the high-temperature sintering temperature is 1030-1080°C, the sintering time is 4-7h, the primary aging temperature is 850-950°C, and the primary aging temperature is 850-950°C. The aging time is 2-4h, the secondary aging temperature is 450-580℃, and the secondary aging time is 3-5h. The sintering process of the present invention is basically applicable to various grades of NdFeB wastes.

Compared with the prior art, the present invention has the following advantages:

The invention adopts the method of adding auxiliary materials to NdFeB waste materials to prepare regenerated NdFeB magnets. By adding auxiliary materials with high rare earth content, the magnetic performance deterioration caused by low rare earth content and high oxygen and carbon content in the waste can be effectively compensated for At the same time, one or more auxiliary materials can be designed according to the different wastes to be processed, and different proportions can be added respectively to modulate the required performance, that is, the auxiliary materials designed by the present invention have universal applicability to different wastes.

Detailed ways

The following are specific embodiments of the present invention, and further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments. Unless otherwise specified, the raw materials involved in the embodiments of the present invention are commonly used raw materials in the field, and the involved methods are conventional methods.

Example 1

The scraps with the grade of N42 are recycled. The recovered defective products are not electroplated or magnetized. The scraps are regenerated according to the following process:

(1) Waste pretreatment: Clean the N42 waste with oil stains on the surface with a decontaminant aqueous solution, then rinse it with water until the surface is clean, and blow dry; polish the N42 waste with an oxide layer on the surface with a polishing machine; The waste is crushed in the intermediate crusher, the particle size after crushing is less than 25mm, and nitrogen protection is used during the crushing process;

(2) Preparation of auxiliary materials: weigh the ingredients according to the mass percentage (PrNd) ₅₇ (AlCuCo) ₃ B ₁ Fe ₃₉ , and smelt the ingredients at 1450° C. and then quickly quench and cool them, so as to obtain ( 0.2-0.4 mm in thickness) ( PrNd) ₅₇ (AlCuCo) ₃ B ₁ Fe ₃₉ alloy ribbon;

(3) Hydrogen crushing: the pretreated waste and the prepared auxiliary materials are mixed according to the mass ratio of 97:3, and the hydrogen crushing furnace is loaded into the hydrogen crushing furnace to obtain coarse powder; wherein the hydrogen absorption pressure is 0.1MPa, and the hydrogen absorption time is 3h. Dehydrogenation temperature 580℃, dehydrogenation time 4h;

(4) Jet mill: Mix the coarse powder and antioxidant which accounts for 0.5‰ of the total weight of the coarse powder in a mixer for 60 minutes, and then send it to the jet mill to obtain fine powder; control the parameters of the jet mill, and grind without adding oxygen. The pressure is 0.6Mpa, the speed of the sorting wheel is 3000rpm, and the SMD of the obtained powder is 3.1μm;

(5) Mixing powder: Mix and stir the fine powder with antioxidant of 0.4‰ of the total weight of fine powder and gasoline of 5‰ in a powder mixer for 120min;

(6) Forming: The mixed fine powder is pressed and formed in a magnetic field forming press under a magnetic field strength of 1.8T, and then further densified in an isostatic press with a maximum pressure of 190MPa;

(7) Vacuum sintering: The green body is sintered at high temperature; the sintering process includes high temperature sintering, primary aging, and secondary aging; The aging time is 2.5h, the secondary aging temperature is 500 ℃, and the secondary aging time is 4h; after the high temperature sintering and the primary aging are completed, it is cooled by argon-filled fast cooling to obtain the NdFeB recycled material.

Example 2

The scraps with the grade of N38UH are recycled. The recovered defective products are not electroplated or magnetized. The scraps are regenerated according to the following process:

(1) Waste pretreatment: Clean the N38UH waste with oily surface with a decontaminant aqueous solution, then rinse it with water until the surface is clean, and blow dry; polish the N38UH waste with an oxide layer on the surface with a polishing machine; The waste is crushed in the intermediate crusher, the particle size after crushing is less than 25mm, and nitrogen protection is used during the crushing process;

(2) According to the mass percentage (DyTb) ₆₀ (AlCuGaCo) ₂ B _0.98 Fe _37.02 , the ingredients are weighed, and the ingredients are smelted at 1460 ° C and then quickly quenched and cooled to be thrown out to obtain (DyTb) ₆₀ with a thickness of 0.2-0.4 mm. (AlCuGaCo) ₂ B _0.98 Fe _37.02 alloy ribbon;

(3) Hydrogen crushing: mix the pretreated waste and the prepared auxiliary materials according to the mass ratio of 97.5:2.5, and put them into the hydrogen crushing furnace; the hydrogen absorption pressure is 0.15MPa, the hydrogen absorption time is 3.5h, and the dehydrogenation temperature is 580 ℃, dehydrogenation time 4.5h;

(4) Jet mill: mix the coarse powder and antioxidant which accounts for 0.6‰ of the total weight of the coarse powder in a mixer for 60 minutes, and then send it into the jet mill to obtain fine powder; control the parameters of the jet mill, and grind without adding oxygen. The pressure is 0.62Mpa, the speed of the sorting wheel is 3100rpm, and the SMD of the obtained powder is 2.9μm;

(5) Mixing powder: Mix and stir the fine powder with antioxidant of 0.6‰ of the total weight of fine powder and gasoline of 6‰ in a powder mixer for 120min;

(6) Forming: The mixed fine powder is pressed and formed in a magnetic field forming press at a magnetic field strength of 2.2T, and then further densified in an isostatic press at a maximum pressure of 200MPa;

(7) Vacuum sintering: the green body is sintered at high temperature; the sintering process includes high temperature sintering, primary aging, and secondary aging; The aging time is 3h, the secondary aging temperature is 490 ℃, and the secondary aging time is 4h; after the high-temperature sintering and the primary aging are completed, it is cooled by argon-filled fast cooling to obtain the NdFeB recycled material.

Example 3

The scraps with the grade of N38SH are recycled. The recovered defective products are not electroplated or magnetized. The scraps are regenerated according to the following process:

(1) Waste pretreatment: Clean the N38SH waste with oily surface with a decontaminant aqueous solution, then rinse it with water until the surface is clean, and blow dry; polish the N38SH waste with an oxide layer on the surface with a polishing machine; The 38SH waste is crushed in the intermediate crusher, and the particle size after crushing is less than 25mm, and nitrogen protection is used in the crushing process;

(2) Preparation of auxiliary materials: weigh the ingredients according to the mass percentage of (PrNd) ₅₇ (AlCuCo) ₃ B ₁ Fe ₃₉ and (DyTb) ₆₀ (AlCuGaCo) ₂ B _0.98 Fe _37.02 , and smelt the ingredients at 1420° C. and then quickly quench and cool them. Throwing out to obtain (PrNd) ₅₇ (AlCuCo) ₃ B ₁ Fe ₃₉ and (DyTb) ₆₀ (AlCuGaCo) ₂ B _0.98 Fe _37.02 alloy thin strips with a thickness of 0.2-0.4 mm;

(3) Hydrogen crushing: Mix the pretreated waste and two kinds of auxiliary materials according to the mass ratio of 97:1.5:1.5, and put them into the hydrogen crushing furnace; the hydrogen absorption pressure is 0.2MPa, the hydrogen absorption time is 3h, and the dehydrogenation temperature 580℃, dehydrogenation time 4h;

(4) Jet mill: Mix the coarse powder and antioxidant which accounts for 0.3‰ of the total weight of the coarse powder in a mixer for 60 minutes, and then send it to the jet mill to obtain fine powder; control the parameters of the jet mill, and grind without adding oxygen. The pressure is 0.61Mpa, the speed of the sorting wheel is 3050rpm, and the SMD of the obtained powder is 3.0μm;

(5) Mixing powder: Mix and stir the fine powder with antioxidant of 0.6‰ of the total weight of the fine powder and gasoline of 7‰ in a powder mixer for 120min;

(6) Forming: The mixed fine powder is pressed and formed in a magnetic field forming press under a magnetic field strength of 2.0T, and then further densified in an isostatic press at a maximum pressure of 210MPa;

(7) Vacuum sintering: the green body is sintered at high temperature; the sintering process includes high temperature sintering, primary aging, and secondary aging; The aging time is 3h, the secondary aging temperature is 490 ℃, and the secondary aging time is 4h; after the high temperature sintering and the primary aging are completed, the cooling is carried out by means of argon filling and rapid cooling, and the NdFeB recycled material is used.

Example 4

The only difference from Example 3 is that the ingredients are weighed according to the mass percentage (NdCe) ₇₀ (AlZrNb) ₂ B _0.5 Fe _27.5 during the preparation of the auxiliary materials.

Example 5

The only difference from Example 3 is that the ingredients are weighed according to the mass percentage (LaCeY) ₅₇ Fe ₄₃ during the preparation of the auxiliary materials.

Example 6

The only difference from Example 3 is that the ingredients are weighed according to the mass percentage (NdLa) ₇₀ (CuZrV) ₁ B _0.2 Fe _28.8 during the preparation of the auxiliary materials.

Example 7

The only difference from Example 3 is that the ingredients are weighed according to the mass percentage (PrNd) ₅₀ (AlCuCo) ₃ B ₁ Fe ₄₆ and (DyTb) ₆₀ (AlCuGaCo) ₂ B _0.98 Fe _37.02 respectively during the preparation of the auxiliary materials.

Example 8

The only difference from Example 3 is that the ingredients are weighed according to the mass percentages of (PrNd) ₅₇ (AlCuCo) ₃ B ₁ Fe ₃₉ and (DyTb) ₅₀ (AlCuGaCo) ₂ B _0.98 Fe _47.02 respectively during the preparation of the auxiliary materials.

Example 9

The only difference from Example 3 is that the ingredients are weighed according to the mass percentages of (PrNd) ₅₀ (AlCuCo) ₃ B ₁ Fe ₄₆ and (DyTb) ₅₀ (AlCuGaCo) ₂ B _0.98 Fe _47.02 respectively during the preparation of the auxiliary materials.

Example 10

The only difference from Example 3 is that the press-formed green body is not subjected to densification treatment.

Example 11

The difference from Example 3 is that the waste was not pretreated.

Example 12

The difference from Example 3 is that no antioxidant is added in the process of jet milling and powder mixing.

Comparative Example 1

The only difference from Example 1 is that no auxiliary material is added.

Comparative Example 2

The only difference from Example 2 is that no auxiliary materials are added.

Comparative Example 3

The only difference from Example 3 is that no auxiliary material is added.

The performance detection of the NdFeB regenerated materials obtained in Examples 1-12 and Comparative Examples 1-3 is carried out, and the results are shown in Table 1 below:

Table 1: The performance results of the NdFeB recycled materials obtained in Examples 1-12 and Comparative Examples 1-3

From the data in Table 1, it can be seen that the coercive force of the regenerated magnet can be greatly improved by adding auxiliary materials with high rare earth content to the waste, and the standard performance requirements can be met. For the treatment of different grades of waste, one or more auxiliary materials can be added to adjust to meet the performance requirements, and the auxiliary materials have universal applicability.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention pertains can make various modifications or additions to the described specific embodiments or substitute in similar manners, but will not deviate from the spirit of the present invention or go beyond the scope defined by the appended claims.

Although the present invention has been described in detail and cited some specific embodiments, it will be apparent to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the present invention.

Claims (9)

1. The regeneration process of the sintered neodymium iron boron waste is characterized by comprising the following steps of:

s1, preprocessing neodymium iron boron waste materials: removing an oxide layer and oil stains on the surface of the waste, and crushing the waste into particles with the particle size of less than 25 mm;

s2, preparing auxiliary materials: weighing auxiliary materials, mixing at the temperature of 1400 ℃ and 1480 ℃, carrying out vacuum melting, cooling and throwing out after quick quenching, and preparing an alloy thin strip; basis of compounding RL_xM_yB_zFe_100-x-y-z、RH_aN_bB_cFe_100-a-b-cAt least one of the above components, wherein x is more than or equal to 57 and less than or equal to 70, y is more than or equal to 0 and less than or equal to 10, and z is more than or equal to 0 and less than or equal to 1; a is more than or equal to 57 and less than or equal to 70, b is more than or equal to 0 and less than or equal to 10, c is more than or equal to 0 and less than or equal to 1, RL and RH are all rare earth elements, M, N are all metal elements, and x, y, z, a, b and c are all mass percentages;

s3, hydrogen crushing: placing the pretreated waste and an alloy thin strip accounting for 0.5-5% of the total weight of the waste into a hydrogen crushing furnace, and crushing to obtain coarse powder;

s4, jet milling: mixing the coarse powder with antioxidant 0.2-0.8 ‰ of the total weight of the coarse powder, and grinding into fine powder with jet mill;

s5, mixing powder: mixing the fine powder with antioxidant 0.3-0.8 ‰ and gasoline 3-8 ‰ based on the total weight of the fine powder;

s6, molding and sintering: and pressing and forming the mixed fine powder, performing densification treatment, and sintering to obtain the neodymium iron boron reclaimed material.

2. The process of claim 1, wherein RL in step S2 is used as the raw material for regenerating sintered NdFeB scrap_xM_yB_zFe_100-x-y-zWherein RL is at least one of La, Ce, Pr, Nd, Pm, Sm and Eu, and M is at least one of Al, Cu, Co, Ga, Zr, Nb and V.

3. The process for regenerating sintered NdFeB wastes according to claim 1, wherein RH in the step S2_aN_bB_cFe_100-a-b-cWherein RH is at least one of Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc, and N is one or more of Al, Cu, Co, Ga, Zr, Nb and V.

4. The process of regenerating sintered nd-fe-b scrap according to claim 1, wherein the thickness of the alloy thin strip in step S2 is 0.2-0.4 mm.

5. The regeneration process of sintered neodymium-iron-boron waste materials according to claim 1, wherein the hydrogen crushing specific process in the step S3 is as follows: vacuumizing, stopping vacuumizing after the vacuum degree reaches below 2Pa, filling hydrogen to make the pressure reach 0.1-0.2Mpa, cooling the furnace body by spraying cooling water, vacuumizing and heating and dehydrogenating the furnace body after hydrogen absorption is saturated, controlling the heating temperature at 590 ℃ of 500 and 590 ℃, and cooling to room temperature after complete dehydrogenation.

6. The process for regenerating sintered NdFeB wastes according to claim 1, wherein the parameters of the air flow milling process in the step S4 are as follows: the oxygen adding amount is 0, the grinding pressure is 0.45-0.65Mpa, and the rotation speed of the sorting wheel is 2800-.

7. The process for regenerating sintered neodymium-iron-boron scrap according to claim 1, characterized in that the average specific surface area particle size of the fine powder in the step S4 is 2.8-3.5 μm.

8. The regeneration process of sintered NdFeB wastes according to claim 1, wherein the magnetic field strength of the compression molding in the step S6 is more than or equal to 1.7T, and the highest isostatic pressure for densification is more than 180 MPa.

9. The process for regenerating sintered NdFeB wastes according to claim 1, wherein the sintering in the step S6 includes high temperature sintering and primary aging and secondary aging; the high-temperature sintering temperature is 1030-1080 ℃, the sintering time is 4-7h, the primary aging temperature is 850-950 ℃, the primary aging time is 2-4h, the secondary aging temperature is 450-580 ℃, and the secondary aging time is 3-5 h.