CN108470616B - Nd prepared from neodymium iron boron solid waste2Fe14Method for preparing B/α -Fe nano composite magnetic powder - Google Patents

Nd prepared from neodymium iron boron solid waste2Fe14Method for preparing B/α -Fe nano composite magnetic powder Download PDF

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CN108470616B
CN108470616B CN201810208373.6A CN201810208373A CN108470616B CN 108470616 B CN108470616 B CN 108470616B CN 201810208373 A CN201810208373 A CN 201810208373A CN 108470616 B CN108470616 B CN 108470616B
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neodymium iron
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刘仲武
田忆兰
钟喜春
邱万奇
焦东玲
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South China University of Technology SCUT
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/10—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
    • H01F1/11—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties

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Abstract

The invention belongs to the field of rare earth permanent magnet waste recovery, and discloses a method for preparing Nd by using neodymium iron boron solid waste2Fe14A process for preparing the nano-class B/α -Fe composite magnetic powder includes such steps as washing the solid waste of Nd-Fe-B, drying, pulverizing, dissolving in strong acid solution, filtering to remove insoluble substance, microwave-aided chemical synthesis, sol-gel process or spray pyrolysis to obtain mixed nano-crystal oxide, and reducing by reducer to obtain Nd2Fe14The method has simple process, is economic and environment-friendly, avoids the defects of long flow, large energy consumption, serious pollution and the like of the traditional hydrometallurgy, simultaneously realizes the high-value utilization of waste materials, and obtains the Nd2Fe14The B/α -Fe nanometer composite magnetic powder has fine crystal grains, uniform components and stronger exchange coupling effect.

Description

Nd prepared from neodymium iron boron solid waste2Fe14Method for preparing B/α -Fe nano composite magnetic powder
Technical Field
The invention belongs to the field of rare earth permanent magnet waste recovery, and particularly relates to a method for preparing Nd by using neodymium iron boron solid waste2Fe14B/α -Fe nanometer composite magnetic powder.
Background
Neodymium iron boron is a permanent magnetic material with high coercive force, high remanence and high magnetic energy product, and is called as 'permanent magnet king'. As a third-generation rare earth permanent magnet, neodymium iron boron is widely applied to motors. Compared with the traditional motor, the neodymium iron boron motor has the advantages of light weight, high efficiency, strong controllability, high cost performance, energy conservation, environmental protection and the like, and is widely applied to a plurality of fields of electronic information, automobile industry, medical equipment, energy traffic and the like. Meanwhile, with the improvement of the comprehensive performance and the reduction of the production cost of the neodymium iron boron, the application of the neodymium iron boron is gradually expanded and enters a plurality of new fields. Under the social theme of energy conservation and environmental protection, industries such as wind power generation, new energy automobiles, energy-saving household appliances and the like will be rapidly developed in the future, and the neodymium iron boron rare earth permanent magnet will have wider market prospect.
Under huge market demand, the yield of neodymium iron boron keeps steadily increasing. About 40% of waste materials are generated in the production process of the neodymium iron boron magnet, and the waste materials contain a large amount of rare earth elements and have great utilization value. Rare earth elements are called "industrial vitamin" and "industrial gold". In recent years, because of the urgent reserves, the supply of neodymium iron boron is in a state of continuous tension, and the development and utilization of rare earth resources have been the current situation of waste exploitation for a long time.
The manufacturing method of the neodymium iron boron magnet mainly comprises two methods of sintering and bonding, wherein the sintered magnet accounts for more than 90% and is a main source of waste materials. The production process flow of the sintered neodymium iron boron is as follows: raw material → pretreatment → batching → smelting → powder making → molding → sintering → tempering heat treatment → mechanical processing and surface treatment → magnetization → performance detection → packaging → product. Waste or defective products are generated at each step in the whole production process. (1) Wastes of various raw materials are generated in the raw material pretreatment and batching process, such as metallic simple substance neodymium, iron, boron, dysprosium, cobalt and the like, mixture ferroboron, mixed rare earth, praseodymium-neodymium alloy and the like; (2) in the traditional process, each stage can generate fragments with different particle sizes in the processes of primary breaking, intermediate breaking and ball milling, most of the prior processes adopt hydrogen explosion and airflow milling to prepare powder, particles with particle sizes larger than the required size can be returned to the airflow milling for secondary treatment in the treatment process, and particles smaller than the required particle sizes are separated out to form part of waste materials; (3) when the magnetic field is oriented and molded, the loss objects such as cracks or unfilled corners caused by demolding are easily generated; (4) during the sintering and tempering processes, defective products with incomplete stress removal, substandard magnetic performance and the like are generated; (5) chips and defective goods generated by wire cutting, grinding, polishing, unqualified plating and the like in the machining and surface treatment processes; (6) defective products caused by insufficient anti-oxidation measures in the preparation process. About 40% of waste materials can be generated in the whole production process of the sintered neodymium iron boron, wherein 35% of waste materials are generated in the machining process, and 5% of waste materials are generated in other processes. Most of the waste is solid except for a small portion of the sludge. The components of the solid wastes are relatively simple, only the surface is partially oxidized and contaminated by oil stains, and the solid wastes can be used as raw materials for preparing the regenerated neodymium iron boron after the oil stains on the surface are removed by a physical method.
At present, the recovery process of the neodymium iron boron waste materials mainly adopts hydrometallurgy, such as sulfuric acid double salt precipitation, hydrochloric acid optimum dissolution, sulfide impurity removal, full extraction and the like, and the process for obtaining the high-purity single rare earth oxide requires a complex and long process, consumes a large amount of acid and organic solvent, causes great waste of iron elements, and reduces the significance of the recovery of the neodymium iron boron waste materials.
Disclosure of Invention
Aiming at the defects and shortcomings of the prior art, the invention aims to provide a method for preparing Nd by using neodymium iron boron solid waste2Fe14The method of B/α -Fe nanometer composite magnetic powder can shorten the technological process, reduce the recovery cost, and synthesize Nd with even components and fine grains2Fe14B/α -Fe nanometer composite magnetic powder.
The purpose of the invention is realized by the following technical scheme:
nd prepared from neodymium iron boron solid waste2Fe14The method for preparing the B/α -Fe nano composite magnetic powder comprises the following steps:
(1) cleaning, drying and crushing the neodymium iron boron solid waste;
(2) dissolving the neodymium iron boron solid waste pretreated in the step (1) by using a strong acid solution, filtering out insoluble substances, and preparing a nanocrystalline mixed oxide from the obtained solution by a microwave-assisted chemical synthesis method, a sol-gel method or a spray pyrolysis method;
(3) reducing the nanocrystalline mixed oxide obtained in the step (2) by a reducing agent to obtain Nd2Fe14B/α -Fe nanometer composite magnetic powder.
Preferably, the pulverization in step (1) means pulverization to a particle size of <400 μm.
Preferably, the strong acid in step (2) refers to at least one of nitric acid, hydrochloric acid and sulfuric acid.
Preferably, soluble salt of at least one element of iron element, boron element and rare earth element is further added to the pretreated neodymium iron boron solid waste material in the step (2). Can be used for adjusting the proportion of the generated nanocrystalline oxide, and further adjusting the components, the structure and the performance of the final magnetic powder.
Preferably, the microwave-assisted chemical synthesis method in step (2) comprises the following specific steps: adding a reducing agent glycine into the obtained solution, stirring and dissolving uniformly, and then putting the solution into a microwave reactor for reaction to obtain the nanocrystalline mixed oxide.
Preferably, the sol-gel method in the step (2) comprises the following specific steps: adding citric acid into the obtained solution, heating, stirring, reacting, standing, cooling to obtain gel, and drying the gel in an oven to obtain dry gel; and carrying out heat treatment on the xerogel to obtain the nanocrystalline mixed oxide.
Preferably, the spray pyrolysis method in the step (2) comprises the following specific steps: stirring the obtained solution, and then carrying out spray drying to obtain a precursor; and (3) carrying out heat treatment and desalination on the precursor to obtain an oxide, and carrying out ball milling to obtain the nanocrystalline mixed oxide.
Preferably, the specific steps of reducing by the reducing agent in the step (3) are: mixing and pressing the nanocrystalline mixed oxide and a solid reducing agent, and reducing the mixture at high temperature in a vacuum state or in a protective gas atmosphere, or putting the nanocrystalline mixed oxide in a reducing gas atmosphere for high-temperature reduction by using a gas reducing agent; the temperature of the high-temperature reduction is 800-1150 ℃, and the reaction time is 1-6 h.
The method of the invention has the following advantages and beneficial effects:
(1) the method of the invention recovers all valuable elements in the neodymium iron boron solid waste together, avoids the complex process of separating rare earth independently and reduces the cost.
(2) The preparation method has the advantages of short reaction time, uniform component organization, no need of consuming a large amount of acid and organic solvent, short flow, less pollution and simple process compared with the traditional wet recovery method.
(3) The reduction product obtained by the invention is Nd2Fe14B/α -Fe nano composite magnetic powder, which can be controlled laterThe preparation process conditions adjust the proportion of two phases, the grain size and the coupling condition, and the two-phase composite magnetic powder has huge development space and wide application prospect.
(4) The regenerated Nd obtained by the invention2Fe14The B/α -Fe nano composite magnetic powder has the advantages of low rare earth content, high remanence and good thermal stability, can be used as a raw material of a bonded magnet and a thermal deformation magnet, can also be used as a high-coercivity magnetic fluid, and has high regeneration value.
Drawings
FIG. 1 shows the regenerated Nd obtained after reduction in step (3) in example 12Fe14XRD pattern of B/α -Fe nano composite magnetic powder.
FIGS. 2 and 3 are views showing the respective regenerated Nd obtained after the reduction in step (3) in example 12Fe14MH and SEM images of B/α -Fe nano-composite magnetic powder.
FIG. 4 shows the regenerated Nd obtained after reduction in step (3) in example 22Fe14XRD pattern of B/α -Fe nano composite magnetic powder.
FIGS. 5 and 6 are views showing the respective regenerated Nd obtained after the reduction in step (3) in example 22Fe14MH and SEM images of B/α -Fe nano-composite magnetic powder.
FIG. 7 shows the regenerated Nd obtained before and after the cleaning in step (3) of example 32Fe14MH diagram of B/α -Fe nano composite magnetic powder.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Example 1
In this example, neodymium iron boron solid waste is used as raw material to prepare regenerated Nd by microwave-assisted chemical synthesis2Fe14The B/α -Fe nanometer composite magnetic powder is prepared by the following steps:
(1) taking 3g of neodymium iron boron solid waste, sequentially placing the neodymium iron boron solid waste into 30ml of ethanol solution and deionized water, respectively carrying out ultrasonic cleaning for 10min, and repeating for 3 times; putting the cleaned sample in a drying oven, and drying for 1h at 80 ℃; the dried sample was milled with a jet mill to a powder with a particle size of <400 μm.
(2) Placing the powder obtained in step (1) in a beaker, and adding 4 mol/L of HNO3Dissolving 50ml of the solution fully, and filtering insoluble substances; adding 3g of reducing agent glycine into the obtained solution, and stirring to fully dissolve the reducing agent glycine; and then putting the obtained solution into a microwave reactor, and reacting for 10min at the power of 800W to obtain the nanocrystalline mixed oxide.
(3) Measuring the phase composition of the nanocrystalline mixed oxide obtained in the step (2), calculating the amount of theoretically required calcium hydride according to the formula ratio, wherein the actual addition amount is 1.1:1, putting the actual addition amount and the theoretical addition amount into an agate mortar, grinding and mixing, and controlling the granularity to be 100-200 mu m; and placing the reactants in a mold for sample pressing to ensure that the oxide is fully contacted with the calcium hydride. And (4) putting the pressed reactant into a tube furnace for reduction reaction. The reaction is carried out at the high temperature under the protection of argon, the reaction temperature is 850 ℃, and the temperature is kept for 2 hours. After the reaction, the mixture is continuously aerated and cooled to the room temperature, and then the furnace is opened for sampling. And (3) placing the obtained reduction product in 50ml of methanol solution, stirring and cleaning, stirring at a speed of 400r/min for 30min, repeating for 3 times, and filtering to remove calcium oxide and calcium hydroxide. Putting the cleaned product in a vacuum drying oven, heating to 50 ℃, and drying for 8h to obtain the regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder.
The XRD pattern of the regenerated nano-composite magnetic powder obtained after the reduction in step (3) of this example is shown in FIG. 1, from which it can be seen that the mixed oxide is reduced to Nd2Fe14B and α -Fe composite magnetic powder, and regenerated Nd obtained after reduction2Fe14MH and SEM images of B/α -Fe nano-composite magnetic powder are shown in FIG. 2 and FIG. 3, respectively, and it can be seen from FIG. 2 that Nd is regenerated2Fe14Saturation magnetization M of B/α -Fe nano composite magnetic powders15.48emu// g, coercive force Hc2293 Oe. FIG. 3 shows that Nd is regenerated2Fe14The size of the B/α -Fe nano composite magnetic powder is about 20-200 nm.
Example 2
In this example, a certain amount of rare earth elements and boron elements are added according to the type and content of the elements in the neodymium iron boron solid waste, and the regenerated Nd is prepared by microwave-assisted chemical synthesis2Fe14B/α -Fe nano-meterThe composite magnetic powder is prepared by the following specific steps:
(1) taking 3g of neodymium iron boron solid waste, sequentially placing the neodymium iron boron solid waste into 30ml of ethanol solution and deionized water, respectively carrying out ultrasonic cleaning for 10min, and repeating for 3 times; putting the cleaned sample in a drying oven, and drying for 1h at 80 ℃; grinding the dried sample into powder with the particle size of less than 400 mu m by using an air flow mill, and analyzing the element types and the content of the powder waste;
(2) by Nd15Fe77B8Adding a certain amount of Nd (NO) into the raw material of the step (1) for the target component3)3And H3BO3The mixed powder was placed in a beaker and 4 mol/L HNO was added3Dissolving 50ml of the solution fully, and filtering insoluble substances; adding 3g of reducing agent glycine into the obtained solution, and stirring to fully dissolve the reducing agent glycine; putting the obtained solution into a microwave reactor, reacting for 10min at the power of 800W to obtain the nanocrystalline mixed oxide.
(3) Measuring the phase composition of the nanocrystalline mixed oxide obtained in the step (2), calculating the amount of theoretically required calcium hydride according to the formula ratio, wherein the actual addition amount is 1.1:1, putting the actual addition amount and the theoretical addition amount into an agate mortar, grinding and mixing, and controlling the granularity to be 100-200 mu m; and placing the reactants in a mold for sample pressing to ensure that the oxide is fully contacted with the calcium hydride. And (4) putting the pressed reactant into a tube furnace for reduction reaction. The reaction is carried out at the high temperature under the protection of argon, the reaction temperature is 950 ℃, and the temperature is kept for 2 hours. After the reaction is finished, continuously introducing air and cooling to room temperature, and then opening the furnace and sampling; placing the obtained reduction product in 50ml of methanol solution, stirring and cleaning, stirring at 400r/min for 30min, repeating for 3 times, and filtering to remove calcium oxide and calcium hydroxide; putting the cleaned product in a vacuum drying oven, heating to 50 ℃, and drying for 8h to obtain the regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder.
The XRF test results of the milled ndfeb solid waste in step (1) of this example are shown in table 1.
TABLE 1 element types and contents table for Nd-Fe-B solid waste
Element(s) Fe Nd Gd Pr Ce Al Others
Content/wt% 63.93 23.85 4.05 2.39 0.68 0.58 0.85
The XRD pattern of the composite magnetic powder obtained after the reduction in step (3) of this example is shown in FIG. 4. It can be seen that the mixed oxide is reduced to Nd2Fe14B and α -Fe composite magnetic powder the MH and SEM images of the composite magnetic powder obtained after reduction are shown in FIGS. 5 and 6, respectively, and it can be seen from FIG. 5 that regenerated Nd is present2Fe14Saturation magnetization M of B/α -Fe nano composite magnetic powders20.14emu// g, coercive force Hc6299 Oe. FIG. 6 shows that Nd is regenerated2Fe14The size of the B/α -Fe nano composite magnetic powder is about 20-200 nm.
Example 3
In the embodiment, neodymium iron boron solid waste is used as a raw material, and a microwave-assisted chemical synthesis method is used to synthesize the high-coercivity regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder, the concrete preparation steps are as follows:
(1) taking 3g of neodymium iron boron solid waste, sequentially placing the neodymium iron boron solid waste into 30ml of ethanol solution and deionized water, respectively carrying out ultrasonic cleaning for 10min, and repeating for 3 times; putting the cleaned sample in a drying oven, and drying for 1h at 80 ℃; grinding the dried sample into powder with the particle size of less than 400 mu m by using an air flow mill, and analyzing the element types and the content of the powder waste;
(2) by Nd15Fe77B8Adding a certain amount of Nd (NO) into the raw material of the step (1) for the target component3)3And H3BO3The mixed powder was placed in a beaker and 4 mol/L HNO was added3Dissolving 50ml of the solution fully, and filtering insoluble substances; adding 3g of reducing agent glycine into the obtained solution, and stirring to fully dissolve the reducing agent glycine; putting the obtained solution into a microwave reactor, reacting for 10min at the power of 900W to obtain the nanocrystalline mixed oxide.
(3) Measuring the phase composition of the nanocrystalline mixed oxide obtained in the step (2), calculating the amount of theoretically required calcium hydride according to the formula ratio, wherein the actual addition amount is 1.1:1, putting the actual addition amount and the theoretical addition amount into an agate mortar, grinding and mixing, and controlling the granularity to be 100-200 mu m; and placing the reactants in a mold for sample pressing to ensure that the oxide is fully contacted with the calcium hydride. And (4) putting the pressed reactant into a tube furnace for reduction reaction. The reaction is carried out at the high temperature under the protection of argon, the reaction temperature is 1050 ℃, and the temperature is kept for 2 hours. After the reaction is finished, continuously introducing air and cooling to room temperature, and then opening the furnace and sampling; placing the obtained reduction product in 50ml of methanol solution, stirring and cleaning, stirring at 400r/min for 30min, repeating for 3 times, and filtering to remove calcium oxide and calcium hydroxide; putting the cleaned product in a vacuum drying oven, heating to 50 ℃, and drying for 8h to obtain the regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder.
The magnetic properties of the obtained nano-composite magnetic powder before and after washing and calcium removal are shown in table 2.
TABLE 2 magnetic properties of nano-composite magnetic powder before and after washing to remove calcium
Sample (I) Ms(emu/g) Br(T) Hc(kOe)
Before cleaning 52.88 0.35 11.303
After cleaning, cleaning 112.20 0.73 10.276
Nd regenerated before and after cleaning obtained in this example2Fe14The MH pattern of the B/α -Fe composite magnetic powder is shown in FIG. 7. it can be seen from Table 2 and FIG. 7 that the saturation magnetization is greatly increased and the coercive force is slightly decreased after the washing to remove calcium.
Example 4
In the embodiment, neodymium iron boron solid waste is used as a raw material to prepare the regenerated Nd by a sol-gel method2Fe14The B/α -Fe nanometer composite magnetic powder is prepared by the following steps:
(1) taking 3g of neodymium iron boron solid waste, sequentially placing the neodymium iron boron solid waste into 30ml of ethanol solution and deionized water, respectively carrying out ultrasonic cleaning for 10min, and repeating for 3 times; putting the cleaned sample in a drying oven, and drying for 1h at 80 ℃; the dried sample was milled with a jet mill to a powder with a particle size of <400 μm.
(2) Placing the powder obtained in step (1) in a beaker, and adding 4 mol/L of HNO3Dissolving 50ml of the solution fully, and filtering insoluble substances; adding a proper amount of citric acid into the solution, uniformly stirring, heating to 80 ℃, stirring for 1h, and cooling to 20 ℃ to obtain sol; putting the sol into a drying oven, and keeping the temperature at 120 ℃ for 2h to obtain gel; carrying out heat treatment on the gel for 2 hours at 800 ℃ in the air to obtain nanocrystalline oxide powder;
(3) measuring the phase composition of the nanocrystalline mixed oxide obtained in the step (2), calculating the amount of theoretically required calcium hydride according to the formula ratio, wherein the actual addition amount is 1.1:1, putting the actual addition amount and the theoretical addition amount into an agate mortar, grinding and mixing, and controlling the granularity to be 100-200 mu m; and placing the reactants in a mold for sample pressing to ensure that the oxide is fully contacted with the calcium hydride. And (4) putting the pressed reactant into a tube furnace for reduction reaction. The reaction is carried out at the high temperature under the protection of argon, the reaction temperature is 850 ℃, and the temperature is kept for 2 hours. After the reaction, the mixture is continuously aerated and cooled to the room temperature, and then the furnace is opened for sampling. And (3) placing the obtained reduction product in 50ml of methanol solution, stirring and cleaning, stirring at a speed of 400r/min for 30min, repeating for 3 times, and filtering to remove calcium oxide and calcium hydroxide. Putting the cleaned product in a vacuum drying oven, heating to 50 ℃, and drying for 8h to obtain the regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder.
Example 5
In the embodiment, neodymium iron boron solid waste is used as a raw material, and the spray pyrolysis method is used for preparing the regenerated Nd2Fe14The B/α -Fe nanometer composite magnetic powder is prepared by the following steps:
(1) taking 3g of neodymium iron boron solid waste, sequentially placing the neodymium iron boron solid waste into 30ml of ethanol solution and deionized water, respectively carrying out ultrasonic cleaning for 10min, and repeating for 3 times; putting the cleaned sample in a drying oven, and drying for 1h at 80 ℃; the dried sample was milled with a jet mill to a powder with a particle size of <400 μm.
(2) Placing the powder obtained in step (1) in a beaker, and adding 4 mol/L of HNO3Dissolving 50ml of the solution fully, and filtering insoluble substances; dissolving the above materials in waterStirring the solution for 2 hours by using a liquid magnetic force, and then performing spray drying by using a miniature spray dryer to obtain a precursor; and (3) carrying out heat treatment on the precursor in the air at 800 ℃ for 2h for desalination to obtain an oxide, and carrying out ball milling to obtain nanocrystalline oxide powder with small size.
(3) Measuring the phase composition of the nanocrystalline mixed oxide obtained in the step (2), calculating the amount of theoretically required calcium hydride according to the formula ratio, wherein the actual addition amount is 1.1:1, putting the actual addition amount and the theoretical addition amount into an agate mortar, grinding and mixing, and controlling the granularity to be 100-200 mu m; and placing the reactants in a mold for sample pressing to ensure that the oxide is fully contacted with the calcium hydride. And (4) putting the pressed reactant into a tube furnace for reduction reaction. The reaction is carried out at the high temperature under the protection of argon, the reaction temperature is 850 ℃, and the temperature is kept for 2 hours. After the reaction, the mixture is continuously aerated and cooled to the room temperature, and then the furnace is opened for sampling. And (3) placing the obtained reduction product in 50ml of methanol solution, stirring and cleaning, stirring at a speed of 400r/min for 30min, repeating for 3 times, and filtering to remove calcium oxide and calcium hydroxide. Putting the cleaned product in a vacuum drying oven, heating to 50 ℃, and drying for 8h to obtain the regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (1)

1. Nd prepared from neodymium iron boron solid waste2Fe14The method for preparing B/α -Fe nano composite magnetic powder is characterized in that a certain amount of rare earth elements and boron elements are added according to the element types and the content of the neodymium iron boron solid waste, and the regenerated Nd is prepared by a microwave-assisted chemical synthesis method2Fe14The B/α -Fe nanometer composite magnetic powder is prepared by the following steps:
(1) taking 3g of neodymium iron boron solid waste, sequentially placing the neodymium iron boron solid waste into 30ml of ethanol solution and deionized water, respectively carrying out ultrasonic cleaning for 10min, and repeating for 3 times; putting the cleaned sample in a drying oven, and drying for 1h at 80 ℃; grinding the dried sample into powder with the particle size of less than 400 mu m by using an air flow mill, and analyzing the element types and the content of the powder waste;
(2) by Nd15Fe77B8Adding a certain amount of Nd (NO) into the raw material of the step (1) for the target component3)3And H3BO3Placing the mixed powder in a beaker, and adding 4 mol/L of HNO3Dissolving 50ml of the solution fully, and filtering insoluble substances; adding 3g of reducing agent glycine into the obtained solution, and stirring to fully dissolve the reducing agent glycine; putting the obtained solution into a microwave reactor, reacting for 10min at the power of 800W to obtain a nanocrystalline mixed oxide;
(3) measuring the phase composition of the nanocrystalline mixed oxide obtained in the step (2), calculating the amount of theoretically required calcium hydride according to the formula ratio, and actually adding the amount: theoretical addition amount is 1.1:1, putting the materials into an agate mortar together, grinding and mixing, wherein the granularity is controlled to be 100-200 mu m; placing the reactant in a mold, pressing the reactant to make the oxide fully contact with the calcium hydride; putting the pressed reactant into a tubular furnace for reduction reaction; the reaction is carried out at the high temperature under the protection of argon, the reaction temperature is 950 ℃, and the temperature is kept for 2 hours; after the reaction is finished, continuously introducing air and cooling to room temperature, and then opening the furnace and sampling; placing the obtained reduction product in 50ml of methanol solution, stirring and cleaning, stirring at 400r/min for 30min, repeating for 3 times, and filtering to remove calcium oxide and calcium hydroxide; putting the cleaned product in a vacuum drying oven, heating to 50 ℃, and drying for 8h to obtain the regenerated Nd2Fe14B/α -Fe nanometer composite magnetic powder.
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