CN115961138B - Regenerated magnetic powder, method for preparing regenerated magnetic powder by chloridizing-reducing diffusion combination method and application thereof - Google Patents
Regenerated magnetic powder, method for preparing regenerated magnetic powder by chloridizing-reducing diffusion combination method and application thereof Download PDFInfo
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Abstract
The invention provides a regenerated magnetic powder, a method for preparing the regenerated magnetic powder by using a chlorination-reduction diffusion combination method and application thereof, wherein the method comprises the following steps: (1) Mixing neodymium iron boron oil sludge and a solid chlorinating agent, and carrying out selective chlorination roasting to obtain a roasting product; (2) And mixing the roasting product with a reducing agent, and performing a calcium reduction diffusion reaction to obtain the regenerated magnetic powder. According to the invention, neodymium iron boron oil sludge is recovered by a chloridizing-calcium reduction diffusion combination method, and the low-oxygen and low-impurity-content regenerated magnetic powder which can be used for preparing the high-performance regenerated sintered magnet is obtained. In addition, the rare earth-rich alloy is doped to prepare the regenerated magnet with excellent performance, so that the problem of low performance of the regenerated magnet caused by high oxygen content of the regenerated magnetic powder is solved. The method can improve the decalcification efficiency and the intrinsic magnetic property of the regenerated magnetic powder, simultaneously can reduce the temperature of the calcium reduction diffusion reaction, reduces the cost, and realizes the purposes of short flow, low cost and green and high-efficiency recovery of the NdFeB oil sludge.
Description
Technical Field
The invention belongs to the technical field of recycling of rare earth permanent magnet waste, and particularly relates to regenerated magnetic powder, a method for preparing the regenerated magnetic powder by using a chlorination-reduction diffusion combination method and application thereof.
Background
The sintered NdFeB magnet is the most important rare earth permanent magnet material, and with the high-speed development of industries such as new energy automobiles, wind power energy conservation, electronic information and the like, the market demand and the yield of the sintered NdFeB in China rise year by year. In 2020, the sintered nd-fe-b magnet yield is about 18.55 ten thousand tons, and during machining of the magnet about 20-30wt.% sludge waste will be produced, which means about 4-6 ten thousand tons of sludge waste will be produced. The sludge waste not only contains about 30wt.% of rare earth elements, but also contains Co, cu, al, ga and other valuable trace elements, and has huge recovery value. Therefore, in recent years, recycling of neodymium iron boron sludge waste has received more and more attention.
At present, the industrial recovery mode of neodymium iron boron oil sludge waste mainly adopts the traditional hydrometallurgical process to separate and extract rare earth elements in the waste, and mainly comprises the steps of oxidizing roasting, acid leaching, neutralization and impurity removal, extraction and separation, oxalic acid precipitation and the like. If neodymium iron boron magnetic powder is to be prepared, a series of links such as molten salt electrolysis, rapid hardening smelting, hydrogen explosion, air flow grinding and the like are needed, the flow is long, the energy consumption is high, and the problem of high pollution caused by the molten salt electrolysis process is also difficult to avoid. In addition, as environmental regulations at home and abroad become stricter, environmental cost of rare earth ore exploitation is increased increasingly; meanwhile, in order to maintain the advantages of rare earth resources in China and improve the social and economic benefits and the sustainable development of rare earth industry, researchers develop new technology and new method for recycling neodymium iron boron oil sludge waste in a green and efficient way.
For example, CN103882234B discloses a method for preparing regenerated neodymium-iron-boron magnetic powder by recovering neodymium-iron-boron sludge waste by using coprecipitation and calcium reduction diffusion technology, but the method has more flow and complicated operation, mixed oxides of rare earth, iron and the like are obtained by using the coprecipitation technology, the consumption of reducing agent metal calcium is increased, the cost is increased, the metal calcium and the iron oxides react vigorously, splashing is easy to generate, the control is not easy, the impurity removal and oxygen control difficulty in the washing process are increased due to the increase of the consumption of calcium, the O, ca content of the obtained regenerated magnetic powder is larger, and the magnetic property is poor.
CN104690277B discloses a method for preparing a regenerated sintered magnet by recovering neodymium iron boron oil sludge by using a reduction diffusion technology, which realizes the regeneration of neodymium iron boron oil sludge through the steps of pretreatment and acid dissolution, coprecipitation and roasting, calcium reduction diffusion, powder mixing and sintering, etc., but the regeneration process destroys the neodymium iron boron phase in the oil sludge, and further requires adding Fe and Fe-B alloy, thereby increasing the consumption of reducing agent in the calcium reduction process, increasing the recovery cost, increasing the difficulty of removing calcium and controlling oxygen in the washing process, and the reduction temperature is higher than 1160 ℃, and the energy consumption is larger.
CN104690270B discloses a short-flow method for preparing regenerated sintered magnet by recovering oil sludge waste material by using a reduction diffusion method, which uses distillation and ultrasonic cleaning to remove organic matters in the waste material, does not need acid dissolution, and directly obtains regenerated magnetic powder by using a reduction diffusion method in the subsequent process, but adds additional Nd in the reduction diffusion process 2 O 3 Raw materials such as Fe-B, and the like, thereby increasing the usage amount of the reducing agent and being unfavorable for reducing the recovery cost. CN109338113B discloses a method for recovering neodymium iron boron trepanning sludge waste by Ca chloride reduction diffusion technology, which proposes that KCl is used as a low melting point auxiliary agent to reduce the reaction temperature and shorten the reaction time, but a blast drying box is used to purify the sludge, so that the oxygen content in the sludge is increased, and the required calcium in the calcium reduction is correspondingly increased, which is not beneficial to reducing the cost. Because the calcium particles are larger, the calcium particles cannot be fully contacted with the oil sludge in the diffusion process, so that the method has the phenomenon of uneven reaction, and the calcium reduction process needs to consume excessive calcium, so that the cost is high.
CN110157916B discloses a low-cost method for preparing high-performance anisotropic neodymium iron boron magnetic powder by using neodymium iron boron oil-based slicing oil sludge, which refers to that the reaction distance can be reduced by pressing reactants into blocks before calcium reduction, diffusion and heating, the sufficiency of reaction is increased to a certain extent, but the recovery throughput is limited by static sintering of the blocks; in addition, it reduces the oxygen content of the regenerated magnetic powder to a certain extent by low-temperature washing and decalcification of the ice-water mixture. However, the byproducts after the calcium reduction and diffusion are all calcium oxide, and the characteristics of indissolvable and insoluble in alcohol are that the calcium oxide is mainly washed and removed by deionized water or ice deionized water in the method, and a large amount of heat is released in the reaction process of the calcium oxide and water to form indissolvable calcium hydroxide, and the solubility of oxygen in water is higher than that of organic solvents such as ethanol, so that the regenerated magnetic powder has the problems of high O content (> 4000 ppm) and the oxygen content of the regenerated magnetic powder even more than 8000ppm after the calcium is washed and removed, incomplete removal of impurity Ca and the like after the calcium is washed and removed, so that the intrinsic magnetic property of the regenerated magnetic powder is lower, and the application of the regenerated magnetic powder in the preparation of the high-performance regenerated sintered neodymium-iron-boron magnet is limited.
In a word, although the recovery of the NdFeB sludge waste by the calcium reduction diffusion method has the great advantages of short process, high efficiency and environmental protection, the problems of large calcium usage amount, high reaction temperature, high O content in the regenerated NdFeB magnetic powder, incomplete removal of impurity Ca and the like still exist.
Therefore, the development of a green and efficient method for preparing the low-oxygen and low-impurity-content regenerated magnetic powder by recycling the NdFeB sludge waste is a technical problem to be solved.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide regenerated magnetic powder, a method for preparing the regenerated magnetic powder by using a chlorination-reduction diffusion combination method and application thereof. According to the invention, neodymium iron boron oil sludge is recovered by a chloridizing-calcium reduction diffusion combination method, and the low-oxygen and low-impurity-content regenerated magnetic powder which can be used for preparing the high-performance regenerated sintered magnet is obtained. The method can improve the decalcification efficiency and the intrinsic magnetic property of the regenerated rare earth permanent magnetic material, can reduce the temperature of the calcium reduction diffusion reaction and the consumption of the reducing agent, and reduces the cost, and the method also achieves the purposes of short flow, low cost and green and efficient recovery of the neodymium iron boron oil sludge.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a regenerative magnetic powder using a combined chlorination-reduction diffusion process, the method comprising the steps of:
(1) Mixing neodymium iron boron oil sludge and a solid chlorinating agent, and carrying out selective chlorination roasting to obtain a roasting product;
(2) And mixing the roasting product with a reducing agent, and performing a calcium reduction diffusion reaction to obtain the regenerated magnetic powder.
According to the invention, neodymium iron boron sludge is recovered by a chloridizing-calcium reduction diffusion combination method, namely rare earth elements in the sludge are selectively converted into chlorine by selective chloridizing roastingRare earth is converted, so that the by-product of calcium reduction diffusion is converted from CaO which is insoluble in water and alcohol into CaCl which is soluble in water and alcohol 2 And further, the regenerated magnetic powder with low oxygen and low impurity content, which can be used for preparing the high-performance regenerated sintered NdFeB magnet, is obtained. The method can improve the decalcification efficiency and the intrinsic magnetic property of the regenerated magnetic powder, can reduce the temperature of the calcium reduction diffusion reaction and reduce the cost, and realizes the purposes of short flow, low cost and green and efficient recovery of the NdFeB oil sludge.
In the invention, the adopted solid chlorinating agent is a low-melting-point chlorinating agent, can play a role of fluxing, can reduce the reaction temperature of calcium reduction and diffusion and the dosage of metal calcium, and reduces the production cost.
Preferably, the solid chlorinating agent of step (1) comprises NH 4 Cl、FeCl 2 、FeCl 3 、AlCl 3 、CoCl 2 、NiCl 2 NaClO or NaClO 3 Any one or a combination of at least two of these.
Preferably, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to the mass ratio of 1-5 times of the rare earth chloride.
In the invention, if the usage amount of the solid chlorinating agent is too small, the selective chlorination reaction is incomplete, and the rare earth component is not fully converted; if the dosage of the solid chlorinating agent is too large, components such as metal Fe and the like easily participate in the chlorination reaction, thereby reducing the selectivity of the chlorination reaction to rare earth components.
Preferably, the selective chlorination roasting in step (1) is carried out in an inert atmosphere or a vacuum atmosphere, the gas in the inert atmosphere comprising nitrogen and/or argon, the vacuum degree in the vacuum atmosphere<1.0×10 -3 Pa may be, for example, 0.8X10 -3 Pa、0.5×10 -3 Pa、0.3×10 -3 Pa、1×10 -4 Pa or 0.5X10 -4 Pa, and the like.
Preferably, the temperature of the chlorination roasting in the step (1) is 250-850 ℃, and the temperature of the selective chlorination roasting can be 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, or the like.
In the present invention, if the temperature of the chlorination roasting is too low, the chlorination reaction is insufficient; if the temperature of the chlorination baking is too high, the chlorinating agent is liable to decompose or volatilize.
Preferably, the time of the selective chlorination roasting in the step (1) is 1-4h, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h, etc.
Preferably, the pretreatment is performed before the neodymium iron boron oil sludge in the step (1) is mixed with the solid chlorinating agent, and the specific steps are as follows:
and (3) cleaning and magnetic separation are sequentially carried out on the oil sludge by using cleaning liquid, and the purified oil sludge is obtained after drying.
Preferably, the cleaning solution used in the cleaning process comprises any one or a combination of at least two of an ethanol solution, a 0.5g/L sodium hydroxide-5% OP emulsifier mixed aqueous solution, a 0.5g/L sodium hydroxide-5% OP emulsifier mixed ethanol solution, a 0.1mol/L hydrochloric acid-5% OP emulsifier mixed aqueous solution or a 0.1mol/L hydrochloric acid-5% OP emulsifier mixed ethanol solution, wherein the 5% OP emulsifier is a model inside the emulsifier OP series (condensate of alkylphenol and ethylene oxide).
Preferably, the reducing agent of step (2) comprises elemental calcium and/or calcium hydride.
Preferably, the mass fraction of the reducing agent in the step (2) is 5-30%, for example, 5%, 10%, 15%, 20%, 25% or 30% based on 100% of the mass of the neodymium iron boron sludge.
In the invention, if the mass fraction of the reducing agent is too small, the reaction is insufficient, and the magnetic powder morphology is poor; if the mass fraction of the reducing agent is too large, more byproducts are generated, which is unfavorable for impurity removal.
Preferably, the calcium reduction diffusion reaction of step (2) is carried out in an inert atmosphere or in a vacuum atmosphere, the gases in the inert atmosphere comprising nitrogen and/or argon, the vacuum degree in the vacuum atmosphere<1.0×10 -3 Pa may be, for example, 0.8X10 -3 Pa、0.5×10 -3 Pa、0.3×10 -3 Pa、1×10 -4 Pa or 0.5X10 -4 Pa, and the like.
Preferably, the temperature of the calcium reduction diffusion reaction in the step (2) is 750-1050 ℃, and for example, 750-800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃ or the like can be used.
Preferably, the time of the calcium reduction diffusion reaction in the step (2) is 1-3h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h or 3h, etc.
Preferably, the method further comprises washing, magnetic separation and drying the reaction product after the calcium reduction diffusion reaction of step (2) is completed.
Preferably, the washing agent comprises any one or a combination of at least two of absolute ethanol, ethylene glycol, n-propanol, n-butanol, n-amyl alcohol, methanol-ammonium chloride solution, methanol-ammonium nitrate, methanol-ammonium acetate, deionized water, propylene glycol or glycerol.
Preferably, the solid to liquid ratio of the reaction product to the detergent is 1g (10-100) mL, which may be, for example, 1g:10mL, 1g:20mL, 1g:30mL, 1g:40mL, 1g:50mL, 1g:60mL, 1g:70mL, 1g:80mL, 1g:90mL, or 1g:100mL, etc.
Preferably, the washing time is 10-180min, for example, 10min, 30min, 50min, 70min, 90min, 120min, 150min or 180min, etc.
Preferably, the number of times of washing is 1 to 3, for example, 1 time, 2 times, 3 times, or the like.
As a preferred technical solution, the method comprises the following steps:
sequentially cleaning and magnetically separating the neodymium iron boron oil sludge by using a cleaning liquid, and drying to obtain purified neodymium iron boron oil sludge;
(II) mixing a solid chlorinating agent with the purified NdFeB oil sludge, and selectively chloridizing and roasting for 1-4 hours in an inert atmosphere or a vacuum atmosphere at the temperature of 250-850 ℃ to obtain a roasting product;
wherein, based on the mass of rare earth chloride, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to 1-5 times of the stoichiometric ratio.
(III) mixing the roasting product with a reducing agent, performing calcium reduction diffusion reaction for 1-3 hours in an inert atmosphere or a vacuum atmosphere at 750-1050 ℃, and washing, magnetic separation and drying after the reaction is finished to obtain the regenerated magnetic powder;
wherein the mass fraction of the reducing agent is 5-30%.
In a second aspect, the present invention provides a regenerated magnetic powder, which is prepared by the preparation method in the first aspect;
preferably, the oxygen content of the regenerated magnetic powder is less than 1500ppm, and may be 1400rpm, 1300rpm, 1200rpm, 1100rpm, 1000rpm, or the like, for example.
In a third aspect, the present invention provides a regenerated sintered nd-fe-b magnet, where the regenerated sintered nd-fe-b magnet is obtained by mixing and sintering the regenerated magnetic powder and the rare earth-rich alloy according to the second aspect.
Preferably, the rare earth-rich alloy is RE-M, where RE represents a rare earth element and M represents a metal alloy.
Preferably, the rare earth-rich alloy comprises RE-Cu, RE-Cu-Al-Ga, (RE) 4 Fe 14 B or RE 6 Fe 13 Any one or a combination of at least two of Ga.
Preferably, the mass fraction of the rare earth-rich alloy is 5-40%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, etc., based on 100% of the mass of the regenerated sintered neodymium-iron-boron magnet.
Preferably, the sintering temperature is 1020-1080 ℃, and may be 1020 ℃, 1030 ℃, 1040 ℃, 1050 ℃, 1060 ℃, 1070 ℃, 1080 ℃ or the like.
Preferably, the sintering time is 3-4h, and may be, for example, 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h, or 4h, etc.
Preferably, the dehydrogenation treatment is performed before sintering.
Preferably, the sintering is followed by an anneal, the anneal comprising a primary anneal and a secondary anneal.
Preferably, the temperature of the primary annealing is 850-900 ℃, and may be 850 ℃, 860 ℃, 870 ℃, 880 ℃, 890 ℃, 900 ℃, or the like, for example.
Preferably, the primary annealing time is 1-3h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, or 3h, etc.
Preferably, the temperature of the secondary annealing is 450-500 ℃, e.g., 450 ℃, 460 ℃, 470 ℃, 480 ℃, 490 ℃, 500 ℃, etc.
Preferably, the time of the secondary annealing is 1-3h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h or 3h, etc.
The numerical ranges recited herein include not only the recited point values, but also any point values between the recited numerical ranges that are not recited, and are limited to, and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values that the recited range includes.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the invention, the NdFeB oil sludge is recovered by a combined method of chloride and calcium reduction diffusion, so that the low-oxygen and low-impurity-content regenerated magnetic powder which can be used for preparing the high-performance regenerated sintered NdFeB magnet is obtained;
(2) The method provided by the invention can improve the calcium removal efficiency and the intrinsic magnetic property of the regenerated magnetic powder, and simultaneously can reduce the temperature of the calcium reduction diffusion reaction and the consumption of the reducing agent, thereby being more beneficial to reducing the cost and obtaining the regenerated magnetic powder with lower oxygen content;
(3) The method provided by the invention can realize the purposes of short flow, low cost and green and efficient recovery of the NdFeB sludge.
Drawings
FIG. 1 shows the ΔG of the main elements of the NdFeB sludge subjected to chlorination reaction θ T -T-plot.
FIG. 2 shows the ΔG of the compound formed by the main elements in the NdFeB sludge subjected to the calcium reduction diffusion reaction θ T -T-plot.
FIG. 3 is an XRD pattern of purified NdFeB sludge and regenerated magnetic powder in example 1 of the present invention.
FIG. 4 shows Nd-doped structure of example 1 and example 2 of the present invention 4 Fe 14 And B, a demagnetization curve of the regenerated sintered NdFeB magnet prepared after the rare earth-enriched alloy powder.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
The following examples all pretreat NdFeB oil sludge, and the specific steps include:
and (3) ultrasonically cleaning the neodymium iron boron oil sludge for 30min by using a mixed ethanol solution of 0.5g/L sodium hydroxide and 5% OP emulsifier, cleaning for 3 times, cleaning for 2 times by using ethanol, and then separating by magnetic separation and drying in vacuum to obtain the purified neodymium iron boron oil sludge.
Example 1
The present embodiment provides a method for preparing a regenerated magnetic powder using a combined chlorination-reduction diffusion method, the method comprising the steps of:
(1) Uniformly mixing 100g of purified neodymium iron boron oil sludge and 35g of ammonium chloride, briquetting under the pressure of 30MPa, and then placing the mixture into a tubular furnace, and preserving the temperature of 400 ℃ for 3 hours under the protection of argon atmosphere for selective chloridizing roasting to obtain a roasting product;
wherein, based on the mass of rare earth chloride, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to 2 times of the stoichiometric ratio;
(2) Mixing the roasting product with 30g of metal calcium, briquetting under 30MPa, carrying out calcium reduction diffusion reaction at 950 ℃ for 3 hours under the protection of argon, grinding the reduction diffusion powder to about 100 meshes after the reaction is finished, putting the powder into a beaker filled with absolute ethyl alcohol according to the solid-to-liquid ratio of 1:100, carrying out ultrasonic cleaning for 2 times for 90 minutes each time, and then carrying out magnetic separation and vacuum drying to obtain regenerated magnetic powder with Ca and O contents of 40ppm and 1400ppm respectively.
The embodiment also provides a regenerated sintered NdFeB magnet, which is prepared by the following steps:
mixing the above regenerated magnetic powder with 30wt.% Nd 4 Fe 14 Uniformly mixing the rare earth-rich alloy powder B, performing orientation profiling under a magnetic field of 1.8T and cold isostatic pressing under 225MPa, sintering at 1070 ℃ for 3 hours after dehydrogenation treatment, and performing primary annealing and secondary annealing at 900 ℃ and 500 ℃ respectively for 3 hours to finally obtain the magnetic property B r ＝12.44，H cj ＝18.28，(BH) max Regenerated sintered neodymium-iron-boron magnet of =37.38 MGOe.
Fig. 3 shows XRD patterns of the purified neodymium iron boron sludge and the regenerated magnetic powder in this example.
Example 2
The present embodiment provides a method for preparing a regenerated magnetic powder using a combined chlorination-reduction diffusion method, the method comprising the steps of:
(1) Uniformly mixing 100g of purified oil sludge and 35g of ammonium chloride, briquetting under the pressure of 30MPa, and then placing the mixture into a tube furnace, and preserving the temperature of 400 ℃ for 3 hours under the protection of nitrogen atmosphere for selective chloridizing roasting to obtain a roasting product;
wherein, based on the mass of rare earth chloride, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to 2 times of the stoichiometric ratio;
(2) Mixing the roasting product with 20g of metal calcium, briquetting under 30MPa, carrying out calcium reduction diffusion reaction at 950 ℃ for 3 hours under nitrogen protection atmosphere, grinding the reduction diffusion powder to about 100 meshes after the reaction is finished, putting the powder into a beaker filled with absolute ethyl alcohol according to a solid-to-liquid ratio of 1:50, carrying out ultrasonic cleaning for 2 times for 90 minutes each time, and then carrying out magnetic separation and vacuum drying to obtain regenerated magnetic powder with Ca and O contents of 20ppm and 100ppm respectively.
The embodiment also provides a regenerated sintered NdFeB magnet, which is prepared by the following steps:
mixing the above regenerated magnetic powder with 20wt.% Nd 4 Fe 14 The rare earth-rich alloy powder B is uniformly mixed, oriented profiling is carried out under a magnetic field of 1.8T, cold isostatic pressing is carried out under 225MPa, sintering is carried out for 3.5 hours at 1050 ℃ after dehydrogenation treatment, and primary annealing is carried out at the temperature of 850 ℃ and 450 ℃ respectivelyAnd a second annealing for 3h, resulting in a magnetic property br=12.50, hcj=17.79, (BH) max Regenerated sintered neodymium-iron-boron magnet of =37.95 MGOe.
Fig. 4 shows examples 1 and 2 doped with Nd 4 Fe 14 And B, a demagnetization curve of the regenerated sintered NdFeB magnet prepared after the rare earth-enriched alloy powder.
Example 3
The present embodiment provides a method for preparing a regenerated magnetic powder using a combined chlorination-reduction diffusion method, the method comprising the steps of:
(1) 100g of NdFeB purified oil sludge and 35g of ammonium chloride are uniformly mixed, pressed into blocks under the pressure of 30MPa, and then put into a tube furnace with the vacuum degree of 0.5 multiplied by 10 -3 Preserving the temperature of 300 ℃ for 4 hours under the vacuum atmosphere of Pa to carry out selective chloridizing roasting to obtain a roasting product;
wherein, based on the mass of rare earth chloride, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to 2 times of the stoichiometric ratio;
(2) Mixing the baked product with 20g of metal calcium, briquetting under 30MPa, and vacuum-forming at 0.5X10 -3 And (3) carrying out calcium reduction diffusion reaction at 750 ℃ for 3 hours under vacuum atmosphere of Pa, grinding the reduction diffusion powder to about 100 meshes after the reaction is finished, putting the powder into a beaker filled with ice deionized water according to a solid-to-liquid ratio of 1:75, carrying out ultrasonic cleaning for 2 times for 90 minutes each time, and then carrying out magnetic separation and vacuum drying to obtain regenerated magnetic powder with Ca and O contents of 20ppm and 1400ppm respectively.
The embodiment also provides a regenerated sintered NdFeB magnet, which is prepared by the following steps:
mixing the above regenerated magnetic powder with 5wt.% Nd 4 Fe 14 Uniformly mixing the rare earth-rich alloy powder B, performing orientation profiling under a magnetic field of 1.8T and cold isostatic pressing under 225MPa, sintering at 1020 ℃ for 4 hours after dehydrogenation treatment, and performing primary annealing and secondary annealing at 870 ℃ and 470 ℃ respectively for 2 hours to finally obtain the magnetic property B r ＝11.66，H cj ＝16.49，(BH) max Regenerated sintering of =31.78 MGOeNeodymium iron boron magnet.
Example 4
The present embodiment provides a method for preparing a regenerated magnetic powder using a combined chlorination-reduction diffusion method, the method comprising the steps of:
(1) Uniformly mixing 100g of NdFeB purified oil sludge and 35g of ammonium chloride, briquetting under the pressure of 30MPa, and then placing the mixture into a tubular furnace, and carrying out selective chlorination roasting at 800 ℃ for 1h under the protection of argon atmosphere to obtain a roasting product;
wherein, based on the mass of rare earth chloride, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to 2 times of the stoichiometric ratio;
(2) Mixing the roasting product with 10g of calcium hydride, briquetting under 30MPa, carrying out calcium reduction diffusion reaction at 1050 ℃ for 1h under the protection of argon, grinding the reduction diffusion powder to about 100 meshes after the reaction is finished, putting the powder into a beaker filled with absolute ethyl alcohol according to the solid-to-liquid ratio of 1:10, carrying out ultrasonic cleaning for 2 times for 90min each time, and then carrying out magnetic separation and vacuum drying to obtain the regenerated magnetic powder with the Ca and O contents of 20ppm and 1000ppm respectively.
The embodiment also provides a regenerated sintered NdFeB magnet, which is prepared by the following steps:
mixing the above regenerated magnetic powder with 10wt.% (Nd-Dy) 70 Cu 30 After being uniformly mixed, the rare earth-rich alloy powder is subjected to orientation profiling under a magnetic field of 1.8T and cold isostatic pressing under 225MPa, is sintered for 3 hours at 1080 ℃ after dehydrogenation treatment, and is subjected to primary annealing and secondary annealing at 880 ℃ and 480 ℃ respectively, wherein the annealing time is 3 hours, and finally the magnetic property is Br=12.25, hcj=23.71, (BH) max Regenerated sintered neodymium-iron-boron magnet of =36.68 MGOe.
FIG. 1 shows the ΔG of the chlorination reaction of the principal elements in the NdFeB sludge provided in examples 1-4 θ T -T-plot.
FIG. 2 shows the ΔG of the compounds formed by the main elements of the NdFeB sludge provided in examples 1-4, undergoing a calcium reduction diffusion reaction θ T -T-plot.
The applicant states that the process of the invention is illustrated by the above examples, but the invention is not limited to, i.e. does not mean that the invention must be carried out in dependence on the above process steps. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of selected raw materials, addition of auxiliary components, selection of specific modes, etc. fall within the scope of the present invention and the scope of disclosure.
Claims (31)
1. A method for preparing regenerated magnetic powder by using a chlorination-reduction diffusion combination method, comprising the following steps:
(1) Mixing neodymium iron boron oil sludge and a solid chlorinating agent, and carrying out selective chlorination roasting to obtain a roasting product;
(2) Mixing the roasting product with a reducing agent, and performing a calcium reduction diffusion reaction to obtain the regenerated magnetic powder;
the solid chlorinating agent is selected from NH 4 Cl、FeCl 3 、AlCl 3 、CoCl 2 、NiCl 2 NaClO or NaClO 3 Any one or a combination of at least two of the following;
the temperature of the selective chlorination roasting in the step (1) is 250-400 ℃.
2. The method of claim 1, wherein the neodymium iron boron sludge is mixed with the solid chlorinating agent in a stoichiometric ratio of 1-5 times based on the mass of the rare earth chloride.
3. The method according to claim 1, wherein the selective chlorination roasting of step (1) is performed in an inert atmosphere or a vacuum atmosphere, the gas in the inert atmosphere including nitrogen and/or argon, the vacuum degree in the vacuum atmosphere<1.0×10 -3 Pa。
4. The method of claim 1, wherein the selective chlorination roasting of step (1) is for a period of 1 to 4 hours.
5. A method according to any one of claims 1 to 3, wherein the neodymium iron boron sludge of step (1) is pre-treated before being mixed with the solid chlorinating agent, and the specific steps are as follows:
and (3) cleaning and magnetic separation are sequentially carried out on the neodymium iron boron oil sludge by using cleaning liquid, and the purified neodymium iron boron oil sludge is obtained after drying.
6. The method of claim 5, wherein the cleaning fluid used in the cleaning process comprises any one or a combination of at least two of an ethanol solution, a 0.5g/L aqueous solution of sodium hydroxide-5% op emulsifier mixture, a 0.1mol/L aqueous solution of hydrochloric acid-5% op emulsifier mixture, or a 0.1mol/L aqueous solution of hydrochloric acid-5% op emulsifier mixture.
7. The method of claim 1, wherein the reducing agent of step (2) comprises elemental calcium and/or calcium hydride.
8. The method according to claim 1, wherein the mass fraction of the reducing agent in the step (2) is 5-30% based on 100% of the mass of the neodymium iron boron sludge.
9. The method according to claim 1, wherein the calcium reduction diffusion reaction of step (2) is performed in an inert atmosphere or a vacuum atmosphere, the gas in the inert atmosphere including nitrogen and/or argon, the vacuum degree in the vacuum atmosphere<1.0×10 -3 Pa。
10. The method of claim 1, wherein the temperature of the calcium reduction diffusion reaction of step (2) is 750-1050 ℃.
11. The method of claim 1, wherein the time for the calcium reduction diffusion reaction of step (2) is 1 to 3 hours.
12. The method of claim 1, further comprising washing, magnetic separation, and drying the reaction product after the calcium reduction diffusion reaction of step (2) is completed.
13. The method of claim 12, wherein the washing uses a detergent comprising any one or a combination of at least two of absolute ethanol, ethylene glycol, n-propanol, n-butanol, n-pentanol, methanol-ammonium chloride solution, methanol-ammonium nitrate solution, methanol-ammonium acetate solution, deionized water, propylene glycol, or glycerol.
14. The method of claim 13, wherein the solid to liquid ratio of the reaction product to the detergent is 1g (10-100) mL.
15. The method of claim 12, wherein the washing is for a period of 10-180 minutes.
16. The method of claim 12, wherein the number of washes is 1-3.
17. The method according to claim 1, characterized in that it comprises the steps of:
sequentially cleaning and magnetically separating the neodymium iron boron oil sludge by using a cleaning liquid, and drying to obtain purified neodymium iron boron oil sludge;
(II) mixing a solid chlorinating agent with the purified NdFeB oil sludge, and selectively chloridizing and roasting for 1-4 hours in an inert atmosphere or a vacuum atmosphere at the temperature of 250-400 ℃ to obtain a roasting product;
wherein, based on the mass of rare earth chloride, the neodymium iron boron oil sludge and the solid chlorinating agent are mixed according to 1-5 times of the stoichiometric ratio;
(III) mixing the roasting product with a reducing agent, performing calcium reduction diffusion reaction for 1-3 hours in an inert atmosphere or a vacuum atmosphere at 750-1050 ℃, and washing, magnetic separation and drying after the reaction is finished to obtain the regenerated magnetic powder;
wherein the mass fraction of the reducing agent is 5-30%.
18. A regenerated magnetic powder prepared by the method of any one of claims 1-17.
19. A reclaimed magnetic powder as claimed in claim 18, wherein the oxygen content of the reclaimed magnetic powder is less than 1500ppm.
20. A regenerated sintered nd-fe-b magnet, wherein the regenerated sintered nd-fe-b magnet is obtained by mixing and sintering the regenerated magnetic powder according to claim 18 with a rare earth-rich alloy powder.
21. The regenerated sintered neodymium-iron-boron magnet according to claim 20, wherein the rare earth-rich alloy is RE-M, wherein RE represents a rare earth element and M represents a metal alloy.
22. The regenerated sintered neodymium-iron-boron magnet according to claim 20, wherein the rare earth-rich alloy comprises RE-Cu, RE-Cu-Al-Ga, (RE) 4 Fe 14 B or RE 6 Fe 13 Any one or a combination of at least two of Ga.
23. The regenerated sintered ndfeb magnet of claim 20, wherein the rare earth-rich alloy is present in an amount of 5-40% by mass based on 100% by mass of the regenerated sintered ndfeb magnet.
24. The regenerated sintered neodymium-iron-boron magnet according to claim 20, wherein the sintering temperature is 1020-1080 ℃.
25. The regenerated sintered neodymium-iron-boron magnet according to claim 20, wherein the sintering time is 3-4 hours.
26. The regenerated sintered neodymium-iron-boron magnet according to claim 20, wherein the dehydrogenation treatment is performed prior to sintering.
27. The regenerated sintered neodymium-iron-boron magnet according to claim 20, wherein said sintering is followed by an anneal, said anneal comprising a primary anneal and a secondary anneal.
28. The regenerated sintered neodymium-iron-boron magnet according to claim 27, wherein the temperature of the primary annealing is 850-900 ℃.
29. The regenerated sintered neodymium iron boron magnet according to claim 27, wherein the primary annealing time is 1 to 3 hours.
30. The regenerated sintered neodymium-iron-boron magnet according to claim 27, wherein the temperature of the secondary annealing is 450-500 ℃.
31. The regenerated sintered neodymium iron boron magnet according to claim 27, wherein the secondary annealing time is 1 to 3 hours.
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