Electrolytic recovery method for neodymium-iron-boron magnet waste

Abstract

An electrolytic recovery method for neodymium-iron-boron magnet waste materials comprises the following steps that the neodymium-iron-boron magnet waste materials are obtained firstly, then a ferric salt solution and acid are mixed to obtain electrolyte, then the neodymium-iron-boron magnet waste materials and the electrolyte are placed in an electrolytic tank, the electrolyte is made to be at the specified temperature, then a power source is turned on, and at the moment, the neodymium-iron-boron magnet waste materials are recycled. Neodymium ions are oxidized into neodymium oxide near the electrolytic anode, ferrous ions are reduced into iron near the electrolytic cathode, and boron ions generate boric acid; taking out iron and neodymium oxide after specified time, pouring calcium salt into the electrolyte after specified time, and precipitating with calcium borate; neodymium, iron and boron can be recycled, so that the neodymium iron boron waste recycling effect is good; neodymium, iron and boron are respectively precipitated in different areas, and the obtained precipitate is relatively pure, so that the recovery efficiency is relatively high. Therefore, the neodymium-iron-boron waste recycling device is good in neodymium-iron-boron waste recycling effect and high in recycling efficiency.

Description

Technical Field

[0001] The invention relates to a method for recycling NdFeB magnet waste, belongs to the field of NdFeB magnet recycling, and in particular to an electrolytic recycling method for NdFeB magnet waste. Background Art

[0002] Neodymium iron boron magnets, also known as neodymium magnets, are the permanent magnetic materials with the strongest magnetic properties in current commercial applications. They are widely used in electronics, motors, sensors, medical devices and other fields. From production to use, neodymium iron boron magnets will produce neodymium iron boron magnet waste. The recycling of neodymium iron boron magnet waste has important economic and environmental significance.

[0003] A Chinese patent application with application number 202311464084.X and application date November 6, 2023 discloses a method for recycling NdFeB waste, permanent magnet ferrite and regenerated rare earth permanent magnet material. The recycling method comprises: (1) selectively salting and roasting a mixture of NdFeB waste and a solid salt agent to obtain a roasting product; (2) leaching and solid-liquid separation of the roasting product obtained in step (1) in turn to obtain a rare earth liquid and a permanent magnet ferrite precursor; (3) precipitating the rare earth liquid obtained in step (2) and then performing solid-liquid separation, calcining the obtained solid, and then electrolyzing the molten salt to obtain a mixed rare earth. Although the design uses a solid salt agent to extract rare earth elements from the waste, it still has the following defects: In this design, the neodymium element is mainly recovered by oxidation. However, the NdFeB magnet waste also includes some waste with a high degree of oxidation, such as iron oxide. This type of waste with a high degree of oxidation does not react in the oxidation reaction, so the iron element cannot be recovered. Therefore, this technology is not effective for the recovery of NdFeB magnet waste.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the application, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects and problems of the prior art in the recycling of NdFeB magnet waste, and to provide an electrolytic recycling method for NdFeB magnet waste with better recycling effect.

[0006] To achieve the above objectives, the technical solution of the present invention is: A method for electrolytic recovery of NdFeB magnet waste, the method comprising the following steps: The first step: first obtain NdFeB magnet waste, then perform surface cleaning treatment on the NdFeB magnet waste, and then obtain the waste to be treated; Step 2: first dissolving the iron salt in water to obtain an iron salt solution, then mixing the iron salt solution with an acid solution to obtain an electrolyte, wherein the concentration of ferrous ions in the electrolyte is 70 g / L-120 g / L, and the pH value of the electrolyte is 3-4; Step 3: firstly put the waste to be processed into the electrolytic cell, then pass the electrolyte into the electrolytic cell, so that the highest liquid level of the electrolyte is higher than the top of the waste to be processed, the top of the electrolytic anode, and the top of the electrolytic cathode, then make the temperature of the electrolyte within the specified temperature range, and then connect the positive electrode of the power supply to the electrolytic anode, and connect the negative electrode of the power supply to the electrolytic cathode; Step 4: Turn on the power first, and the current density in the electrolyte is the specified current density. At this time, an oxidation reaction occurs near the electrolytic anode, so the neodymium ions are oxidized to neodymium oxide, and the neodymium oxide is then precipitated at the electrolytic anode in the form of flakes; a reduction reaction occurs near the electrolytic cathode, so the ferrous ions are reduced to iron, and the iron is then precipitated at the electrolytic cathode in the form of flakes; the boron ions react with the acid ions in the electrolyte to generate boric acid; Step 5: After the first designated time has passed, first turn off the power supply, then remove the iron from the electrolytic cathode, and then remove the neodymium oxide from the electrolytic anode; Step 6: After the second specified time, turn off the power first, then extract the electrolyte from the electrolytic cell, then pass the electrolyte into the sedimentation tank, then pour calcium salt into the sedimentation tank, then the calcium salt reacts with boric acid to regenerate calcium borate precipitate, and then take out the calcium borate from the sedimentation tank.

[0007] In the second step, the acid solution is an inorganic acid solution or an organic acid solution.

[0008] In the second step, the inorganic acid solution is a sulfuric acid solution or a hydrochloric acid solution.

[0009] In the second step, the iron salt is ferrous sulfate or ferrous chloride.

[0010] In the third step, the specified temperature range is less than or equal to 50°C.

[0011] In the third step, the specified temperature range is greater than or equal to 10°C.

[0012] In the fourth step, the specified current density is 30A / ㎡-100A / ㎡.

[0013] In the fifth step, the first designated time is one to two weeks; In the sixth step, the second designated time is one to two months.

[0014] In the third step, the electrolytic anode includes a titanium pressing plate and a titanium mesh, a surface of the titanium pressing plate is uniformly provided with a plurality of through holes, and an outer surface of the titanium pressing plate is covered with a titanium mesh.

[0015] In the third step, the electrolytic cathode is a stainless steel plate soaked in an organic solution.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In the electrolytic recovery method of NdFeB magnet waste of the present invention, the method comprises the following steps: the first step: firstly obtain NdFeB magnet waste, and then perform surface cleaning treatment on the NdFeB magnet waste to obtain waste to be treated; the second step: firstly mix the iron salt solution with the acid solution to obtain an electrolyte, the concentration of ferrous ions in the electrolyte is 70g / L-120g / L, and the pH value of the electrolyte is 3-4; the third step: firstly put the waste to be treated and the electrolyte into the electrolytic cell, and then make the temperature of the electrolyte within the specified temperature range, and then place the electrolytic anode and the electrolytic cathode at a temperature of 100°C. The first step is to connect the electrode to the power supply; the fourth step is to turn on the power supply first, at this time, an oxidation reaction occurs at the electrolytic anode, the neodymium ions are oxidized to neodymium oxide, and the neodymium oxide sheet is precipitated at the electrolytic anode, and a reduction reaction occurs at the electrolytic cathode, the ferrous ions are reduced to iron, and the iron sheet is precipitated at the electrolytic cathode, and the boron ions react with the acid radical ions in the electrolyte to generate boric acid; the fifth step is to remove the iron sheet from the electrolytic cathode and the neodymium oxide sheet from the electrolytic anode after the first specified time; after the second specified time, the electrolyte is passed into the precipitation tank to react with the calcium salt to generate calcium borate precipitation. The advantages of the present invention also include: First point: Neodymium oxide is generated through oxidation reaction to achieve the recovery of neodymium element, iron flakes are generated through reduction reaction to achieve the recovery of iron element, and calcium borate is generated by reacting borate with calcium salt to achieve the recovery of boron element; compared with the existing technology, the recovery of three elements can be achieved, so the recovery effect is better; Second point: Neodymium oxide is precipitated at the electrolytic anode, iron flakes are precipitated at the electrolytic cathode, and calcium borate is precipitated in the precipitation tank. The precipitates in the three areas are single and the precipitates obtained are relatively pure, so the recovery efficiency is high; Third point: When the electrolyte is passed into the precipitation tank to react with the calcium salt to form calcium borate precipitation, the acid radical ions in the calcium salt are replenished into the electrolyte, so the electrolyte can be passed into the electrolytic cell again for recycling; Third point: When the concentration of ferrous ions is 70g / L-120g / L, the quality of iron generated by electrolysis is the best. When the pH value of the electrolyte is 3-4, iron is most easily leached. At this time, the acidity of the electrolyte is lower than that of concentrated acid. Only a small amount of oxygen will be produced in the electrolysis reaction, which will not affect the environment. Therefore, the present invention has a better recycling effect on NdFeB waste and a higher recycling efficiency.

[0017] 2. In the electrolytic recovery method of NdFeB magnet waste of the present invention, in the second step, the acid solution is an inorganic acid solution or an organic acid solution, and the inorganic acid solution is a sulfuric acid solution or a hydrochloric acid solution. When used, the acid radical ions in the acid solution react with the boron ions to generate borate radicals, so as to facilitate the subsequent collection of calcium borate. The pH value of the acid solution is low, the reaction is relatively slow, and only a small amount of oxygen is generated in the electrolytic reaction, and no toxic and harmful gases are released, so it will not affect the environment. Therefore, the present invention is green and environmentally friendly.

[0018] 3. In the electrolytic recovery method of NdFeB magnet waste of the present invention, in the third step, the specified temperature range is 10℃-50℃, and in the fourth step, the specified current density is 30A / ㎡-100A / ㎡. When applied, the electrolytic reaction speed is fastest when the temperature of the electrolyte is 10℃-50℃, and the room temperature is generally between 10℃-50℃, so in most cases, the electrolyte does not need to be heated, so the energy consumption of this method is low, while in the reaction process of the prior art, it needs to be heated to 400 to 750 degrees, so the energy consumption is large; when the current density in the electrolyte is 30A / ㎡-100A / ㎡, it is most conducive to the leaching of iron. Therefore, the energy consumption of the present invention is low.

[0019] 4. In the electrolytic recovery method of NdFeB magnet waste of the present invention, in the fifth step, the first designated time is one to two weeks, and in the sixth step, the second designated time is one to two months. When applied, the neodymium oxide and iron sheet are collected every one to two weeks; the calcium borate is collected every one to two months. Each time the collection is performed, sufficient neodymium oxide, iron sheet and calcium borate are generated. The collection frequency does not lead to a large amount of labor, and the neodymium oxide, iron sheet and calcium borate are not too heavy to be difficult to remove. When calcium borate is generated, an acid solution is generated, and the acid solution is introduced into the electrolytic cell for recycling. Therefore, the collection frequency of the present invention is appropriate.

[0020] 5. In the electrolytic recovery method of NdFeB magnet waste of the present invention, in the third step, the electrolytic anode is a titanium platen wrapped with a titanium mesh, and a plurality of through holes are evenly distributed on the titanium platen, and the electrolytic cathode is a stainless steel plate soaked in an organic solution. When used, the electrolytic anode uses a titanium platen wrapped with a titanium mesh, which has a larger contact area with the waste to be processed, and reduces the contact resistance, which can reduce the voltage and is conducive to the precipitation of neodymium oxide. The electrolytic cathode uses a stainless steel plate soaked in an organic solution, and its surface stress is uniform, which will not cause the iron sheet to warp during the precipitation process of the iron sheet, thereby avoiding the short circuit of the iron sheet connecting the electrolytic cathode to the electrolytic anode in the case of warping. Therefore, the continuous application effect of the present invention is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 yes Figure 1 Schematic diagram of the structure of the electrolytic cell.

[0023] Figure 3 yes Figure 1 Schematic diagram of the structure of the electrolytic anode.

[0024] Figure 4 yes Figure 3 Left view of .

[0025] Figure 5 yes Figure 3 Schematic diagram of the structure of Zhongti Network.

[0026] Figure 6 yes Figure 1 Schematic diagram of the structure of the electrolytic cathode.

[0027] Figure 7 yes Figure 6 Left view of .

[0028] Figure 8 yes Figure 2 Schematic diagram of the structure of the filtration device.

[0029] Fig. 9 yes Figure 8 Enlarged view of the stirring paddle.

[0030] In the figure: electrolyte 1, electrolytic cell 11, sedimentation tank 12, electrolyte liquid level 13, electrolytic anode 2, titanium pressure plate 21, titanium mesh 22, power supply 3, electrolytic cathode 4, filtering device 5, stirring paddle 51, first partition 52, second partition 53. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] See also Figure 1 — Fig. 9 , a method for electrolytic recovery of NdFeB magnet waste, the method comprising the following steps: The first step: first obtain NdFeB magnet waste, then perform surface cleaning treatment on the NdFeB magnet waste, and then obtain the waste to be treated; Step 2: first dissolving the iron salt in water to obtain an iron salt solution, then mixing the iron salt solution with an acid solution to obtain an electrolyte 1, wherein the concentration of ferrous ions in the electrolyte 1 is 70 g / L-120 g / L, and the pH value of the electrolyte 1 is 3-4; Step 3: firstly put the waste to be processed into the electrolytic cell 11, then pass the electrolyte 1 into the electrolytic cell 11, so that the highest liquid level of the electrolyte 1 is higher than the top of the waste to be processed, the top of the electrolytic anode 2, and the top of the electrolytic cathode 4, then make the temperature of the electrolyte 1 within the specified temperature range, then connect the positive electrode of the power supply 3 to the electrolytic anode 2, and connect the negative electrode of the power supply 3 to the electrolytic cathode 4; Step 4: First, turn on the power supply 3, and the current density in the electrolyte 1 is the specified current density. At this time, an oxidation reaction occurs near the electrolytic anode 2, so the neodymium ions are oxidized to neodymium oxide, and the neodymium oxide is then precipitated in the form of flakes at the electrolytic anode 2; a reduction reaction occurs near the electrolytic cathode 4, so the ferrous ions are reduced to iron, and the iron is then precipitated in the form of flakes at the electrolytic cathode 4; the boron ions react with the acid radical ions in the electrolyte to generate boric acid; Step 5: After the first specified time has passed, first turn off the power supply, then take out the iron from the electrolytic cathode 4, and then take out the neodymium oxide from the electrolytic anode 2; Step 6: After the second specified time, turn off the power first, then extract the electrolyte 1 from the electrolytic cell 11, then pass the electrolyte into the sedimentation tank 12, then pour calcium salt into the sedimentation tank 12, then the calcium salt reacts with boric acid to regenerate calcium borate precipitate, and then take out the calcium borate from the sedimentation tank 12.

[0033] In the second step, the acid solution is an inorganic acid solution or an organic acid solution.

[0034] In the second step, the inorganic acid solution is a sulfuric acid solution or a hydrochloric acid solution.

[0035] In the second step, the iron salt is ferrous sulfate or ferrous chloride.

[0036] In the third step, the specified temperature range is less than or equal to 50°C.

[0037] In the third step, the specified temperature range is greater than or equal to 10°C.

[0038] In the fourth step, the specified current density is 30A / ㎡-100A / ㎡.

[0039] In the fifth step, the first designated time is one to two weeks; In the sixth step, the second designated time is one to two months.

[0040] In the third step, the electrolytic anode 2 includes a titanium pressing plate 21 and a titanium mesh 22 . The surface of the titanium pressing plate 21 is evenly distributed with a plurality of through holes, and the outer surface of the titanium pressing plate 21 is covered with a titanium mesh 22 .

[0041] In the third step, the electrolytic cathode 4 is a stainless steel plate soaked in an organic solution.

[0042] The supplementary description of the present invention is as follows: The NdFeB magnet waste described in the present invention is: the waste has two sources, the first source is: the NdFeB magnet waste generated in each process from raw material pretreatment to product testing during the production of sintered NdFeB; the second source is: the sintered NdFeB waste in the form of sheets, blocks and other shapes with coatings disassembled from various magnetic devices that are scrapped after use (i.e., demagnetized), that is, the NdFeB magnet waste; in the NdFeB magnet waste, the NdFeB magnet is a tetragonal crystal formed by neodymium, iron and boron, wherein the rare earth metal neodymium accounts for 29%-32.5%, iron accounts for 63.95%-68.65%, and boron accounts for 1.1%-1.2%.

[0043] Embodiment 1: See also Figure 1 — Fig. 9 , a method for electrolytic recovery of NdFeB magnet waste, the method comprising the following steps: The first step: first obtain NdFeB magnet waste, then perform surface cleaning treatment on the NdFeB magnet waste, and then obtain the waste to be treated; Step 2: first dissolving the iron salt in water to obtain an iron salt solution, then mixing the iron salt solution with an acid solution to obtain an electrolyte 1, wherein the concentration of ferrous ions in the electrolyte 1 is 70 g / L-120 g / L, and the pH value of the electrolyte 1 is 3-4; Step 3: firstly put the waste to be processed into the electrolytic cell 11, then pass the electrolyte 1 into the electrolytic cell 11, so that the highest liquid level of the electrolyte 1 is higher than the top of the waste to be processed, the top of the electrolytic anode 2, and the top of the electrolytic cathode 4, then make the temperature of the electrolyte 1 within the specified temperature range, then connect the positive electrode of the power supply 3 to the electrolytic anode 2, and connect the negative electrode of the power supply 3 to the electrolytic cathode 4; Step 4: First, turn on the power supply 3, and the current density in the electrolyte 1 is the specified current density. At this time, an oxidation reaction occurs near the electrolytic anode 2, so the neodymium ions are oxidized to neodymium oxide, and the neodymium oxide is then precipitated in the form of flakes at the electrolytic anode 2; a reduction reaction occurs near the electrolytic cathode 4, so the ferrous ions are reduced to iron, and the iron is then precipitated in the form of flakes at the electrolytic cathode 4; the boron ions react with the acid radical ions in the electrolyte to generate boric acid; Step 5: After the first specified time has passed, first turn off the power supply, then take out the iron from the electrolytic cathode 4, and then take out the neodymium oxide from the electrolytic anode 2; Step 6: After the second specified time, turn off the power first, then extract the electrolyte 1 from the electrolytic cell 11, then pass the electrolyte into the sedimentation tank 12, then pour calcium salt into the sedimentation tank 12, then the calcium salt reacts with boric acid to regenerate calcium borate precipitate, and then take out the calcium borate from the sedimentation tank 12.

[0044] Embodiment 2: The basic content is the same as that of Example 1, except that: See also Figure 1 — Figure 8 In the second step, the acid solution is an inorganic acid solution or an organic acid solution. In the second step, the inorganic acid solution is a sulfuric acid solution or a hydrochloric acid solution. In the second step, the iron salt is ferrous sulfate or ferrous chloride.

[0045] When applied, in the second step, ferrous sulfate or ferrous chloride is first dissolved in water to obtain a ferrous sulfate solution or a ferrous chloride solution, and then the ferrous sulfate solution or the ferrous chloride solution is mixed with an acid solution to obtain an electrolyte 1; wherein the acid solution is an inorganic acid solution or an organic acid solution, and the inorganic acid solution can be a sulfuric acid solution or a hydrochloric acid solution; in the electrolyte 1, the concentration of ferrous ions is 70g / L-120g / L to ensure the electrolytic leaching of iron in the NdFeB magnet waste. If the concentration of ferrous ions is lower than 70g / L, the quality of the electrolytic iron is reduced. If the concentration of ferrous ions is higher than 120g / L, not only the electrolysis The fluidity of electrolyte 1 is reduced, which will also lead to waste of raw materials; the pH value of electrolyte 1 is 3-4. If the pH value of electrolyte 1 is higher than 4, hydrogen evolution will occur at the electrolytic cathode, which will cause the quality of the iron sheet to deteriorate. After the iron sheet is generated, it will fall off or warp. At this time, the iron sheet may connect the electrolytic cathode with the electrolytic anode, thereby causing a short circuit; and compared with the wet recovery in the prior art (using concentrated acid to acid-leach the waste to be treated), the acid volatility and acidity of this electrolyte 1 are relatively small, and it is more environmentally friendly; the pH value of electrolyte 1 can be slightly adjusted by adding ammonia (or other alkali) or acid.

[0046] Embodiment 3: The basic content is the same as that of Example 1, except that: See also Figure 1 — Figure 8 In the third step, the specified temperature range is less than or equal to 50° C. In the third step, the specified temperature range is greater than or equal to 10° C. In the fourth step, the specified current density is 30A / ㎡-100A / ㎡.

[0047] When applied, in the third step, the temperature of the electrolyte 1 is set to 10°C-50°C. In most cases, room temperature can meet this temperature range. If the temperature of the electrolyte 1 is lower than 10°C, the production efficiency is low. If the temperature of the electrolyte 1 is higher than 50°C, the energy consumption increases. The current density in the electrolyte 1 is 30A / ㎡-100A / ㎡. This range is most conducive to the leaching of iron. If the current density is lower than 30A / ㎡, the production efficiency is low. If the current density is higher than 100A / ㎡, side reactions will occur.

[0048] Embodiment 4: The basic content is the same as that of Example 1, except that: See also Figure 1 — Fig. 9 In the fifth step, the first designated time is one to two weeks; in the sixth step, the second designated time is one to two months. Preferably, the first to sixth steps are performed in a cycle. Preferably, the sedimentation tank 12 comprises a first baffle 52, a second baffle 53 and a stirring paddle 51, and one end of the sedimentation tank 12 is connected to the filtering device 5.

[0049] When applied, in the fifth step, every one to two weeks, the iron sheet on the electrolytic cathode 4 is peeled off to obtain the recovered iron sheet, and then the electrolytic cathode 4 is installed back to its original position; then the neodymium oxide is rinsed with deionized water until the resistance of the rinsed washing solution (pure water) is not less than 1MΩ•cm, and then the neodymium oxide on the electrolytic anode 2 is peeled off to obtain the recovered neodymium oxide, and then the electrolytic anode 2 is installed back to its original position; in the sixth step, every one to two months, calcium sulfate or calcium chloride is added to the sedimentation tank 12, and then the calcium sulfate or calcium chloride is mixed with the electrolyte 1. The boric acid reacts to generate calcium borate, sulfuric acid or hydrochloric acid and water. At this time, a suspension is obtained, and then the suspension is introduced into the filter device 5 for filtration. After filtration, the calcium borate solid is taken out, and the acid solution is obtained after filtration. Therefore, the acid solution is introduced into the electrolytic cell 11, and it can be recycled after measuring and adjusting the pH value; if the acid solution in the second step is sulfuric acid, the calcium salt is calcium sulfate, and if the acid solution in the second step is hydrochloric acid, the calcium salt is calcium chloride; in the above process, the first partition 52 and the second partition 53 are used to prevent the electrolyte 1 from flowing back, and the stirring paddle 51 stirs to increase the reaction speed.

[0050] Embodiment 5: The basic content is the same as that of Example 1, except that: See also Figure 1 — Figure 8 In the third step, the electrolytic anode 2 includes a titanium pressing plate 21 and a titanium mesh 22, and a plurality of through holes are evenly distributed on the surface of the titanium pressing plate 21, and the outer surface of the titanium pressing plate 21 is covered with a titanium mesh 22. In the third step, the electrolytic cathode 4 is a stainless steel plate soaked in an organic solution. Preferably, the organic solution is an organic sulfonamide, an aromatic sulfonate, a sulfamide, or an aldehyde, alcohol, or pyridine organic compound. Preferably, the organic solution is a sodium saccharin solution. Preferably, the organic solution is 1,4-butynediol.

[0051] When used, a plurality of through holes are evenly distributed on the titanium pressure plate 21, and the titanium mesh 22 is a mesh structure, so the contact area between the two and the electrolyte waste to be treated is large, which is conducive to the oxidation to generate neodymium oxide; and the structure of the titanium pressure plate 21 and the titanium mesh 22 reduces the contact resistance and reduces the required voltage; the acidity near the electrolytic anode 2 is strong, which will leach out the iron-containing substances that have not been completely reacted, and then use a magnet to recover this part of the iron-containing substances to increase the output ratio; the electrolytic cathode 4 is a stainless steel plate soaked in an organic solution, and the organic solution makes the stress on the outer surface of the stainless steel plate uniform, so that the iron sheet is smooth and bright during the generation process, and the edge warping phenomenon will not occur, so it can prevent the iron sheet from falling off, or the electrolytic anode 2 and the electrolytic cathode 4 from being connected due to edge warping.

[0052] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A method for electrolytic recovery of NdFeB magnet waste, characterized in that: The method comprises the following steps: The first step: first obtain NdFeB magnet waste, then perform surface cleaning treatment on the NdFeB magnet waste, and then obtain the waste to be treated; Step 2: first dissolving the iron salt in water to obtain an iron salt solution, then mixing the iron salt solution with an acid solution to obtain an electrolyte (1), wherein the concentration of ferrous ions in the electrolyte (1) is 70 g / L-120 g / L, and the pH value of the electrolyte (1) is 3-4; Step 3: firstly, the waste to be treated is placed in the electrolytic cell (11), and then the electrolyte (1) is introduced into the electrolytic cell (11) so that the highest liquid level of the electrolyte (1) is higher than the top of the waste to be treated, the top of the electrolytic anode (2), and the top of the electrolytic cathode (4), and then the temperature of the electrolyte (1) is within a specified temperature range, and then the positive electrode of the power supply (3) is connected to the electrolytic anode (2), and the negative electrode of the power supply (3) is connected to the electrolytic cathode (4); Step 4: First, turn on the power supply (3), and the current density in the electrolyte (1) is the specified current density. At this time, an oxidation reaction occurs near the electrolytic anode (2), so that the neodymium ions are oxidized to neodymium oxide, and the neodymium oxide is then precipitated in the form of flakes at the electrolytic anode (2); a reduction reaction occurs near the electrolytic cathode (4), so that the ferrous ions are reduced to iron, and the iron is then precipitated in the form of flakes at the electrolytic cathode (4); the boron ions react with the acid radical ions in the electrolyte to generate boric acid; Step 5: After the first specified time has passed, first turn off the power supply, then remove the iron from the electrolytic cathode (4), and then remove the neodymium oxide from the electrolytic anode (2); Step 6: After the second specified time has passed, the power supply is turned off, and then the electrolyte (1) is extracted from the electrolytic cell (11), and then the electrolyte is passed into the sedimentation tank (12), and then calcium salt is poured into the sedimentation tank (12), and then the calcium salt reacts with boric acid to generate calcium borate precipitate, and then the calcium borate is taken out from the sedimentation tank (12).

2. The electrolytic recovery method of NdFeB magnet waste according to claim 1, characterized in that: In the second step, the acid solution is an inorganic acid solution or an organic acid solution.

3. The electrolytic recovery method of NdFeB magnet waste according to claim 2, characterized in that: In the second step, the inorganic acid solution is a sulfuric acid solution or a hydrochloric acid solution.

4. The electrolytic recovery method of NdFeB magnet waste according to claim 3, characterized in that: In the second step, the iron salt is ferrous sulfate or ferrous chloride.

5. The electrolytic recovery method of NdFeB magnet waste according to claim 1, characterized in that: In the third step, the specified temperature range is less than or equal to 50°C.

6. The electrolytic recovery method of NdFeB magnet waste according to claim 5, characterized in that: In the third step, the specified temperature range is greater than or equal to 10°C.

7. The electrolytic recovery method of NdFeB magnet waste according to claim 6, characterized in that: In the fourth step, the specified current density is 30A / ㎡-100A / ㎡.

8. The electrolytic recovery method of NdFeB magnet waste according to claim 1, characterized in that: In the fifth step, the first designated time is one to two weeks; In the sixth step, the second designated time is one to two months.

9. The electrolytic recovery method of NdFeB magnet waste according to claim 1, characterized in that: In the third step, the electrolytic anode (2) comprises a titanium pressing plate (21) and a titanium mesh (22), the surface of the titanium pressing plate (21) being evenly distributed with a plurality of through holes, and the outer surface of the titanium pressing plate (21) being covered with the titanium mesh (22).

10. The electrolytic recovery method of NdFeB magnet waste according to claim 1, characterized in that: In the third step, the electrolytic cathode (4) is a stainless steel plate soaked in an organic solution.

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