Leaching method of neodymium-iron-boron waste and method for extracting and separating iron and neodymium from leachate

Abstract

The invention provides a method for leaching neodymium-iron-boron waste, and particularly relates to a method for extracting and separating iron and neodymium from leachate. According to the leaching method disclosed by the invention, the degradable citric acid is used for replacing hydrochloric acid or sulfuric acid which is heavily polluted to be used as a leaching agent, so that an excellent leaching effect is achieved, and the pollution problem of acid wastewater is greatly controlled; the lixivium is directly used for solvent extraction and separation of iron and neodymium in the lixivium, and an excellent separation effect is achieved; the leaching efficiency of iron and neodymium can reach 99% or above; according to the method for extracting and separating the iron and the neodymium from the leachate, the leachate serves as a water phase for extraction, the selectivity of N235 and the high efficiency of P350 are integrated, the iron is efficiently extracted from the mixed solution, the single-stage extraction efficiency of the iron in the leachate is higher than 99%, the extraction efficiency of the neodymium is lower than 10%, and the separation coefficient of the iron and the neodymium can reach 13000; meanwhile, the single-stage reverse extraction efficiency of iron can reach 80% or above, and deep separation of iron and neodymium is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of leaching and extracting and separating valuable metals neodymium and iron in NdFeB waste, and in particular to a method for leaching NdFeB waste and a method for extracting and separating iron and neodymium in a leaching solution. Background Art

[0002] Rare earth permanent magnet materials are permanent magnet materials made from rare earth elements (Pr, Nd, Dy) and transition elements (Fe, Ni, Co) through a certain process. Among them, NdFeB is the representative. It is called "magnet king" because of its excellent magnetic properties and is widely used in machinery, electronics, instrumentation, medical treatment and new energy fields. China is a major producer and consumer of NdFeB permanent magnet materials in the world. Affected by the production process, the utilization rate of raw materials is only about 75%, which will produce 25% of waste. In addition to the abandoned and retired permanent magnet materials, the annual NdFeB waste can reach tens of tons. The proper treatment of these secondary resources has become an important factor restricting the development of rare earth permanent magnet materials.

[0003] The comprehensive recycling of NdFeB secondary resources is mainly achieved through metallurgical methods. The most commonly used is the direct reuse method, which is considered to be the best method for recycling bulk NdFeB waste. The sintered NdFeB is simply treated and then directly used in the production process to produce new NdFeB permanent magnet materials. Due to oxidation, the magnetic properties of the newly produced NdFeB permanent magnet materials have a certain decline. Secondly, pyrometallurgy is mainly used, using rapid reaction kinetics at high temperatures to separate and purify rare earth elements through metallurgical physical and chemical reactions, including molten metal refining, selective oxidation, chlorination, calcium reduction, and phase separation. Although rare earths can be directly extracted from NdFeB waste, most NdFeB waste has a certain degree of oxidation. At this time, the pyrometallurgical process is no longer applicable, and expensive metal extractants also restrict development.

[0004] Hydrometallurgy is the most widely used method in industry at present. Hydrometallurgy is divided into complete dissolution and optimal dissolution. Complete dissolution is to transfer valuable elements (rare earth elements, transition elements) from the solid state to the leachate in the form of ions or other soluble complexes, and then separate the valuable elements through oxidation, extraction and other processes. The complete dissolution method is simple to operate and can recover all valuable elements, but the consumption of hydrochloric acid is large in the process of dissolving waste, and a large amount of impurity ions will be dissolved during the dissolution process, which will affect the purity of rare earth products. The optimal dissolution method uses the different solubility and dissolution time of rare earth elements and transition metal elements in acid, the preferential dissolution of rare earth elements, and the slightly soluble or insoluble characteristics of transition metal elements to separate and recover rare earth and transition metals. The optimal dissolution method can greatly reduce the consumption of acid and alkali, but it needs to undergo certain pretreatment (such as roasting) to convert the metal into the corresponding oxide before separation and purification can be achieved. At the same time, there is a certain contradiction between the selectivity and efficiency of leaching, which makes it difficult to control the roasting conditions and the kinetics of rare earth leaching reaction slow, which greatly limits the deep separation of rare earth and transition metals. If the temperature is not properly controlled during high-temperature roasting, a certain amount of NdFeO will be produced. 3 , it is very stable and difficult to be leached, which will cause a large loss of valuable components.

[0005] For the full dissolution method, the main processes of industrial recycling currently include: acid leaching, alkali precipitation, and solvent extraction separation. The main constraints are the generation of acidic wastewater, incomplete precipitation of iron ions, low extraction efficiency of rare earths, low separation ratio, and multiple extraction stages. Therefore, the development of efficient and green leaching systems and efficient separation and extraction systems for iron and neodymium will make a huge contribution to the separation and recovery of NdFeB secondary resources.

[0006] Based on the defects of the current NdFeB waste recycling, it is necessary to improve it. Summary of the invention

[0007] In view of this, the present invention proposes a method for leaching NdFeB waste and a method for extracting and separating iron and neodymium from the leaching solution to solve or at least partially solve the defects of the prior art.

[0008] In a first aspect, the present invention provides a method for leaching NdFeB waste, comprising the following steps:

[0009] The NdFeB waste is added into a citric acid aqueous solution, and the solution is leached at 50-90° C. for 15-240 minutes. After the leaching is completed, a leachate is obtained.

[0010] Preferably, the concentration of the citric acid aqueous solution is 0.02-1.0 mol / L.

[0011] Preferably, the solid-to-liquid ratio of the NdFeB waste to the citric acid aqueous solution is (5-20) g:1L.

[0012] Preferably, the NdFeB waste is added to a citric acid aqueous solution and leached at 80° C. for 90 minutes;

[0013] The concentration of the citric acid aqueous solution is 0.2 mol / L;

[0014] The solid-to-liquid ratio of the NdFeB waste to the citric acid aqueous solution is 10g:1L.

[0015] In a second aspect, the present invention also provides a method for extracting and separating iron and neodymium from a leaching solution, comprising the following steps:

[0016] Obtaining a leachate according to the method;

[0017] Mix the leaching solution and leaching agent, add H 2 O 2 The solution and the diluent are mixed to obtain a diluent;

[0018] After mixing the diluent, sulfonated kerosene and extractant, perform extraction reaction at 15-55°C for 1-120 minutes;

[0019] After the extraction reaction, separation is performed to obtain a lower layer liquid and an upper layer liquid;

[0020] Add H to the upper liquid 2 SO 4 Solution, back extraction reaction at 15-55°C for 5-120 minutes;

[0021] After the stripping reaction, separation is performed again to obtain the lower layer liquid.

[0022] Preferably, the leaching agent is a 0.2 mol / L citric acid aqueous solution;

[0023] The diluent is a 0.2 mol / L citric acid aqueous solution;

[0024] The extractant includes any one of N235, P350, P507, a mixed extractant of N235 and P350, a mixed extractant of N235 and P204, a mixed extractant of N235 and 507, and a mixed extractant of N235 and Cyanex272;

[0025] The leachate, leachate, H 2 O 2 The volume ratio of the solution is (30-35) mL: (90-95) mL: (10-15) mL;

[0026] The H 2 O 2 The mass concentration of the solution is 30-35%;

[0027] The volume of the diluent is proportional to the volume of the leaching solution, leaching agent, H 2 O 2 The ratio of the sum of the volumes of the solutions is (1~2):(1~2).

[0028] Preferably, the extractant is a mixed extractant of N235 and P350;

[0029] The volume ratio of N235 and P350 is (1-5):(1-5);

[0030] The volume ratio of the diluent, sulfonated kerosene and extractant is (5-15) mL: (5-25) mL: (0.1-1.2) mL;

[0031] Preferably, the volume ratio of N235 to P350 is 1:1;

[0032] The volume ratio of the diluent, sulfonated kerosene, and extractant is 5 mL:5 mL:0.4 mL;

[0033] The diluent, sulfonated kerosene and extractant were mixed and subjected to extraction reaction at 25°C for 3 minutes.

[0034] Preferably, H is added to the upper liquid. 2 SO 4 The solution is subjected to a stripping reaction at 15 to 55° C. for 5 to 120 minutes; the H 2 SO 4 The concentration of the solution is 0.5-3.0 mol / L; the upper liquid and H 2 SO 4 The volume of the solution was 4mL:4mL.

[0035] Preferably, H is added to the upper liquid. 2 SO 4 The solution was stripped at 25°C for 60 min. 2 SO 4 The concentration of the solution is 1.5 mol / L.

[0036] The method for leaching NdFeB waste and the method for extracting and separating iron and neodymium from the leaching solution of the present invention have the following beneficial effects compared with the prior art:

[0037] 1. The leaching method of NdFeB waste of the present invention uses citric acid (CA) aqueous solution as a leaching agent, and uses degradable citric acid instead of hydrochloric acid or sulfuric acid with greater pollution as a leaching agent, thereby achieving excellent leaching effect and greatly controlling the pollution problem of acidic wastewater; subsequently, the leaching solution is directly used for solvent extraction to separate iron and neodymium therein, and both of them show excellent separation effect; at the same time, the experimental process is simplified, the integrated operation of leaching-extraction is completed, and the efficient separation and recovery of valuable metals in NdFeB waste is realized; in the present invention, a low-concentration citric acid (CA) aqueous solution is used as a leaching agent, and citric acid is a ternary organic weak acid, which is highly soluble and has excellent biodegradability. Under the optimal leaching conditions, the leaching efficiency of iron and neodymium can reach more than 99%;

[0038] 2. The method for extracting and separating iron and neodymium from the leachate of the present invention adopts a solvent extraction system, uses the leachate as the aqueous phase for extraction, combines the selectivity of N235 and the efficiency of P350, and uses the mixture of the two as an extractant to efficiently extract iron from the mixed solution. Under the best experimental conditions, the single-stage extraction efficiency of iron in the leachate is higher than 99%, while the extraction efficiency of neodymium is lower than 10%, and the separation coefficient of iron and neodymium can reach 13000; at the same time, the single-stage stripping efficiency of iron can reach more than 80%, achieving the deep separation of iron and neodymium. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 This is a graph showing the effect of citric acid aqueous solution on the leaching efficiency of two metal ions, iron and neodymium, in Example 1 of the present invention;

[0041] Figure 2 This is a diagram showing the effect of the liquid-to-solid ratio on the leaching efficiency of two metal ions, iron and neodymium, in Example 2 of the present invention;

[0042] Figure 3 This is a graph showing the effect of leaching temperature on the leaching efficiency of two metal ions, iron and neodymium, in Example 3 of the present invention;

[0043] Figure 4 This is a graph showing the effect of leaching time on the leaching efficiency of two metal ions, iron and neodymium, in Example 4 of the present invention;

[0044] Figure 5 This is a graph showing the effect of the type of extractant on the extraction efficiency of iron and neodymium in Example 6 of the present invention;

[0045] Figure 6 This is a graph showing the effect of the ratio of the extractant on the extraction efficiency of iron and neodymium in Example 7 of the present invention;

[0046] Figure 7 This is a graph showing the effect of the amount of extractant used on the extraction efficiency of iron and neodymium in Example 8 of the present invention;

[0047] Figure 8 This is a graph showing the effect of the volume ratio of 60# sulfonated kerosene to diluent on the extraction efficiency of iron and neodymium in Examples 9 to 13 of the present invention;

[0048] Fig. 9 Graph showing the effect of extraction time on the extraction efficiency of iron and neodymium in Example 14 of the present invention;

[0049] Fig.10 Graph showing the effect of extraction temperature on the extraction efficiency of iron and neodymium in Example 15 of the present invention;

[0050] Fig.11 is H in Example 16 of the present invention 2 SO 4 Effect of concentration on iron stripping efficiency;

[0051] Fig.12 Graph showing the effect of stripping temperature on iron stripping efficiency in Example 17 of the present invention;

[0052] Fig.13 This is a graph showing the effect of stripping time on the stripping efficiency of iron in Example 18 of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0055] The present application embodiment provides a method for leaching NdFeB waste, comprising the following steps:

[0056] The NdFeB waste is added into a citric acid aqueous solution, and the solution is leached at 50-90° C. for 15-240 minutes. After the leaching is completed, a leachate is obtained.

[0057] The leaching method of NdFeB waste material of the present invention uses citric acid (CA) aqueous solution as a leaching agent, and uses degradable citric acid instead of hydrochloric acid or sulfuric acid with greater pollution as a leaching agent, thereby achieving excellent leaching effect and greatly controlling the pollution problem of acidic wastewater; subsequently, the leaching liquid is directly used for solvent extraction to separate iron and neodymium therein, and both of them show excellent separation effect; at the same time, the experimental process is simplified, the integrated operation of leaching-extraction is completed, and the efficient separation and recovery of valuable metals in NdFeB waste material is realized.

[0058] The present invention first places NdFeB waste in a citric acid aqueous solution, leaches at a certain temperature and time, and then oxidizes the leached solution and directly uses it for solvent extraction to separate iron and neodymium. The present invention can efficiently leach iron and neodymium in NdFeB waste, and can efficiently separate iron and neodymium therein by solvent extraction, thereby providing a cheap and efficient method for separating and recovering iron and neodymium in NdFeB secondary resources.

[0059] In some embodiments, the concentration of the citric acid aqueous solution is 0.02-1.0 mol / L.

[0060] In some embodiments, the solid-to-liquid ratio of NdFeB waste to citric acid aqueous solution is (5-20) g:1L.

[0061] In some embodiments, NdFeB waste is added to a citric acid aqueous solution and leached at 80° C. for 90 minutes;

[0062] The concentration of citric acid aqueous solution is 0.2 mol / L;

[0063] The solid-to-liquid ratio of NdFeB waste to citric acid aqueous solution is 10g:1L.

[0064] In the present invention, a low concentration of citric acid (CA) aqueous solution is used as a leaching agent. Citric acid is a ternary organic weak acid, highly soluble, and has excellent biodegradability. Under optimal leaching conditions, the leaching efficiency of iron and neodymium can reach more than 99%.

[0065] Based on the same inventive concept, the present invention also provides a method for extracting and separating iron and neodymium from a leaching solution, comprising the following steps:

[0066] S1, obtaining a leachate according to the above method;

[0067] S2, mix the leaching solution and leaching agent, add H 2 O 2 The solution and the diluent are mixed to obtain a diluent;

[0068] S3, after mixing the diluent, sulfonated kerosene and extractant, extract and react at 15-55°C for 1-120 minutes;

[0069] S4, after the extraction reaction, separation is performed to obtain a lower layer liquid and an upper layer liquid;

[0070] S5. Add H to the upper liquid 2 SO 4 Solution, back extraction reaction at 15-55°C for 5-120 minutes;

[0071] S6. After the back extraction reaction, separation is performed again to obtain a lower layer of liquid.

[0072] The method for extracting and separating iron and neodymium from a leaching solution of the present invention comprises mixing the leaching solution obtained according to the above method with a leaching agent, and then adding H 2 O 2 The solution is oxidized, and then a diluent is added to mix to obtain a diluent; the diluent, sulfonated kerosene, and an extractant are mixed, and an extraction reaction is carried out at 15 to 55° C. for 1 to 120 minutes; after the extraction reaction, the lower layer liquid and the upper layer liquid are separated, and specifically, the lower layer liquid is an aqueous phase containing neodymium, and the upper layer liquid is an organic phase containing iron; H is added to the upper layer liquid. 2 SO 4 Solution, H 2 SO 4 The solution is used as a stripping agent, and the stripping reaction is carried out at 15 to 55° C. for 5 to 120 minutes. After the stripping reaction, separation is performed again to obtain a lower layer of liquid, which is an aqueous phase containing iron (ferric sulfate), thereby achieving separation of iron and neodymium.

[0073] In some embodiments, the leaching agent is a 0.2 mol / L citric acid aqueous solution;

[0074] In some embodiments, the diluent is a 0.2 mol / L citric acid aqueous solution;

[0075] In some embodiments, the extractant includes any one of N235, P350, P507, a mixed extractant of N235 and P350, a mixed extractant of N235 and P204, a mixed extractant of N235 and 507, and a mixed extractant of N235 and Cyanex272.

[0076] Specifically, N235 is trioctyldecyl tertiary amine, commonly known as 7301 extractant;

[0077] P350 is dimethylheptyl methylphosphonate;

[0078] P507 is 2-ethylhexyl phosphate mono-2-ethylhexyl ester;

[0079] P204 is di(2-ethylhexyl) phosphate;

[0080] Cyanex272 extractant is bis(2,4,4-trimethylpentyl)phosphonic acid.

[0081] In some embodiments, the sulfonated kerosene is 260# sulfonated kerosene, 260# solvent oil.

[0082] In some embodiments, the leachate, leachate, H 2 O 2 The volume ratio of the solution is (30-35) mL: (90-95) mL: (10-15) mL;

[0083] H 2 O 2 The mass concentration of the solution is 30-35%;

[0084] In some embodiments, the volume of the diluent is proportional to the volume of the leachate, leachate, H 2 O 2 The ratio of the sum of the volumes of the solutions is (1~2):(1~2).

[0085] In some embodiments, the extractant is a mixed extractant of N235 and P350;

[0086] The volume ratio of N235 and P350 is (1-5):(1-5);

[0087] In some embodiments, the volume ratio of the diluent, sulfonated kerosene, and extractant is (5-15) mL: (5-25) mL: (0.1-1.2) mL;

[0088] The volume ratio of N235 and P350 is 1:1;

[0089] In some embodiments, the volume ratio of the diluent, sulfonated kerosene, and extractant is 5 mL:5 mL:0.4 mL;

[0090] The diluent, sulfonated kerosene and extractant were mixed and subjected to extraction reaction at 25°C for 3 minutes.

[0091] In some embodiments, H is added to the upper liquid. 2 SO 4 The solution is subjected to a stripping reaction at 15 to 55° C. for 5 to 120 minutes; the H 2 SO 4 The concentration of the solution is 0.5-3.0 mol / L; the upper liquid and H 2 SO 4 The volume of the solution was 4mL:4mL.

[0092] In some embodiments, H is added to the upper liquid. 2 SO 4 The solution was stripped at 25°C for 60 min. 2 SO 4 The concentration of the solution is 1.5 mol / L.

[0093] The high-efficiency leaching system of the present invention has an excellent leaching effect on NdFeB waste, and the leaching solution can directly separate the iron and neodymium therein by solvent extraction. The solvent extraction system adopted by the present invention uses the leaching solution as the aqueous phase for extraction, combines the selectivity of N235 and the high efficiency of P350, and uses the mixture of the two as the extractant to efficiently extract iron from the mixed solution. Under the best experimental conditions, the single-stage extraction efficiency of iron in the leaching solution is higher than 99%, while the extraction efficiency of neodymium is lower than 10%, and the separation coefficient of iron and neodymium can reach 13000; at the same time, the single-stage stripping efficiency of iron can reach more than 80%, achieving the deep separation of iron and neodymium.

[0094] The following further describes the leaching method of NdFeB waste and the method for extracting and separating iron and neodymium in the leachate of the present application. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0095] The NdFeB scrap used in the following examples was purchased from Magnequench (Tianjin) Co., Ltd., wherein the mass fraction of iron was 73.1%, the mass fraction of neodymium was 25.8%, the mass fraction of boron was 1%, and the rest were unavoidable impurities.

[0096] The calculation formulas for leaching efficiency, extraction efficiency, and stripping efficiency in the following examples are as follows:

[0097] (1) Calculation formula for leaching efficiency:

[0098]

[0099] In the above formula, E 铁 / 钕 It represents the extraction efficiency of iron / neodymium, %; C represents the concentration of metal ions in the leachate after leaching, mg / L; V represents the volume of the leachate, L; m represents the mass of NdFeB waste, mg; wt% represents the mass fraction of metal, that is, 73.1% for iron and 25.8% for neodymium.

[0100] (2) Extraction efficiency calculation formula:

[0101]

[0102] In the above formula, E is the extraction efficiency of metal ions; C 0 , C e Represents the initial concentration and equilibrium concentration of metal ions in the raffinate, mg / L.

[0103] (3) Distribution ratio and separation coefficient:

[0104]

[0105] In the above formula, C 0 , C e Same as (2); D represents the distribution ratio, D Nd That is, the distribution ratio of neodymium, D Fe That is, it represents the distribution ratio of iron; β represents the separation coefficient of Nd and Fe.

[0106] (4) Stripping efficiency:

[0107]

[0108] In the above formula, E s Represents stripping efficiency, %; C 0 , C e Same as (2); C s represents the concentration of metal ions in the raffinate after stripping, which is H 2 SO 4 The concentration of metal ions in a solution.

[0109] Example 1

[0110] This embodiment provides a method for leaching NdFeB waste, comprising the following steps:

[0111] 0.30 g of NdFeB waste was added to 30 mL of 0.02 mol / L citric acid aqueous solution, and the solution was leached at 80°C for 60 min. After the leaching was completed, a leachate was obtained. After the leachate was cooled to room temperature (25°C), 2 mL of the leachate was diluted 10 times with a 3% dilute nitric acid solution (the volume after dilution was 20 mL). Then, the concentrations of iron and neodymium therein were detected by ICP-OES, and the leaching efficiency of iron and neodymium was calculated (calculated according to formula 1). The results are as follows: Figure 1 30mL of citric acid aqueous solutions with concentrations of 0.04mol / L, 0.06mol / L, 0.08mol / L, 0.1mol / L, 0.20mol / L, 0.40mol / L, 0.60mol / L, 0.80mol / L, and 1.0mol / L were prepared respectively. According to the same method as in Example 1, citric acid aqueous solutions of different concentrations were used to leach neodymium iron boron (NdFeB) waste to obtain leachates, and the leaching efficiencies of iron and neodymium were calculated. The results are as follows: Figure 1 shown. Figure 1 The horizontal axis represents the concentration of citric acid aqueous solution, and the vertical axis represents the leaching efficiency.

[0112] from Figure 1 It can be seen that the leaching efficiency of iron and neodymium increases with the increase of the concentration of citric acid (CA) aqueous solution. From 0.02 mol / L to 0.2 mol / L, the leaching efficiency of iron increases from 18.80% to 97.11%, and the leaching efficiency of neodymium increases from 13.68% to 94.13%. When the concentration of CA is greater than 0.2 mol / L, the leaching efficiency of iron and neodymium gradually decreases. Therefore, 0.2 mol / LCA aqueous solution is preferred for subsequent experiments.

[0113] Example 2

[0114] This embodiment provides a method for leaching NdFeB waste, comprising the following steps:

[0115] 0.30 g of NdFeB waste was added to 30 mL of 0.2 mol / L citric acid aqueous solution (solid-to-liquid ratio S / L was 5 g / L), and the solution was leached at 80° C. for 60 min. After the leaching was completed, a leachate was obtained. After the leachate was cooled to room temperature (25° C.), 2 mL of the leachate was diluted 10 times with a dilute nitric acid solution with a mass concentration of 3%. The concentrations of iron and neodymium therein were then detected by ICP-OES, and the leaching efficiency of iron and neodymium was calculated (calculated according to formula 1). The results are as follows: Figure 2 shown.

[0116] According to the method in Example 2, 0.30 g, 0.45 g, and 0.60 g of neodymium iron boron (NdFeB) waste were added to 30 mL, 0.2 mol / L citric acid aqueous solution, respectively, to obtain leachate, and the leaching efficiency of iron and neodymium was calculated. The results are as follows: Figure 3 As shown in the figure, 0.30g, 0.45g, and 0.60g of NdFeB waste were added to 30mL, 0.2mol / L citric acid aqueous solution, and the corresponding solid-liquid ratios S / L were 10g / L, 15g / L, and 20g / L, respectively.

[0117] from Figure 2 It can be seen that the leaching efficiency of iron and neodymium decreases with the increase of solid-liquid ratio. When the solid-liquid ratio changes from 5g / L to 10g / L, the leaching efficiency of iron and neodymium remains almost unchanged, both of which remain above 99%; when the solid-liquid ratio is greater than 10g / L, the leaching efficiency of iron and neodymium begins to decrease. Therefore, 10g / L is set as the solid-liquid ratio for subsequent experiments.

[0118] Example 3

[0119] This embodiment provides a method for leaching NdFeB waste, comprising the following steps:

[0120] 0.30g of NdFeB waste was added to 30mL of 0.2mol / L citric acid aqueous solution, and the solution was leached at 50°C for 60min. After the leaching was completed, a leachate was obtained. After the leachate was cooled to room temperature (25°C), 2mL of the leachate was diluted by a certain multiple with a 3% dilute nitric acid solution, and then the concentrations of iron and neodymium therein were detected by ICP-OES, and the leaching efficiency of iron and neodymium was calculated. The results are as follows: Figure 3 shown.

[0121] According to the method in Example 3, the reaction temperature was set to 60°C, 70°C, 80°C, and 90°C (the reaction time was unchanged at 60 min), and leaching was performed to obtain a leachate. The leaching efficiency of iron and neodymium was calculated. The results are as follows: Figure 3 shown.

[0122] from Figure 3 It can be seen that the leaching efficiency of iron and neodymium increases slowly with the increase of temperature. When the temperature rises to 80°C, the leaching efficiency of iron has reached 99.75%, and the leaching efficiency of neodymium has reached 96.33%. When the temperature exceeds 80°C, the leaching efficiency basically does not change, so 80°C is taken as the optimal leaching temperature.

[0123] Example 4

[0124] This embodiment provides a method for leaching NdFeB waste, comprising the following steps:

[0125] 0.30g of NdFeB waste was added to 30mL of 0.2mol / L citric acid aqueous solution, and the solution was leached at 80°C for 15min. After the leaching was completed, a leachate was obtained. After the leachate was cooled to room temperature (25°C), 2mL of the leachate was diluted 10 times with a 3% dilute nitric acid solution by mass, and then the concentrations of iron and neodymium therein were detected by ICP-OES, and the leaching efficiency of iron and neodymium was calculated. The results are as follows: Figure 4 shown.

[0126] According to the method in Example 3, the reaction time was set to 30min, 45min, 60min, 90min, 120min, 180min, and 240min respectively (the reaction temperature was unchanged at 80°C), leaching was carried out to obtain a leachate, and the leaching efficiency of iron and neodymium was calculated. The results are as follows: Figure 4 shown.

[0127] from Figure 4 It can be seen that the leaching efficiency of iron and neodymium gradually increases with the increase of time. When the time increases from 15min to 90min, the leaching efficiency of iron increases from 50.08% to 99.86%, and the leaching efficiency of neodymium increases from 49.56% to 99.51%. When the leaching time continues to increase, the leaching efficiency basically does not change, so 90min is taken as the optimal leaching time.

[0128] Example 5

[0129] This embodiment provides a pretreatment method for NdFeB waste leachate, comprising the following steps:

[0130] S1, adding 0.30g of neodymium iron boron (NdFeB) waste to 30mL of 0.2mol / L citric acid aqueous solution, and leaching reaction at 80°C for 60min, after leaching, obtaining a leachate;

[0131] S2, take 30mL of the leaching solution and add 90mL of the leaching agent (0.2mol / L citric acid aqueous solution), stir evenly; then add 10mL of 30% H 2 O 2 solution, at which point the leachate changes from green to orange-yellow;

[0132] S3. Take 50 mL of the orange-yellow solution obtained in S2, add an equal volume (i.e. 50 mL) of diluent (0.2 mol / L citric acid aqueous solution), and stir evenly to obtain the diluent to be extracted and separated.

[0133] Example 6

[0134] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0135] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.5 mL of extractant N235, extract and react at room temperature (25°C) for 10 min;

[0136] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2 mL of the lower layer liquid (the lower layer liquid is the raffinate) and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency (Extraction efficiency) and separation coefficient (Separation coefficient) of iron and neodymium. The results are as follows: Figure 5 shown.

[0137] According to the same method as in Example 6, the extractant N235 was replaced by P350, P507, a composite extractant of N235 and P350 (N235+P350, the volume ratio of N235 to P350 was 1:1), a composite extractant of N235 and P204 (N235+P204, the volume ratio of N235 to P204 was 1:1), a composite extractant of N235 and P507 (N235+P507, the volume ratio of N235 to P507 was 1:1), and a composite extractant of N235 and Cyanex272 (N235+Cyanex272, the volume ratio of N235 to Cyanex272 was 1:1), and the extraction efficiency and separation coefficient of iron and neodymium were calculated in the same way. The results are as follows: Figure 5 shown.

[0138] from Figure 5 It can be seen that the extraction efficiency of iron and neodymium is closely related to the type of extractant. In the presence of N235, the extraction efficiency of iron is higher, the extraction efficiency of neodymium is lower, and the separation effect of the two is better; in addition, the effect of binary extractant is significantly better than that of single extractant. From the experimental results, the effect of N235-P350 binary extractant is slightly better than that of other extractants, so it will be used for the next experiment.

[0139] Example 7

[0140] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0141] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.5 mL of N235 and P350 composite extractant, extract and react for 10 min at room temperature (25°C); the volume ratio of N235 to P350 is 5:1;

[0142] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 6 shown.

[0143] According to the same method as in Example 7, the volume ratios of N235 and P350 were set to 3:1, 1:1, 1:3, and 1:5, respectively, and the extraction efficiencies of iron and neodymium were calculated in the same manner. The results are as follows: Figure 6 shown. Figure 6 NP-5 means that the volume ratio of N235 and P350 is 1:5, NP-3 means that the volume ratio of N235 and P350 is 1:3, NP means that the volume ratio of N235 and P350 is 1:1, 3-NP means that the volume ratio of N235 and P350 is 3:1, and 5-NP means that the volume ratio of N235 and P350 is 5:1.

[0144] from Figure 6 It can be seen that the extraction efficiency of iron and neodymium is closely related to the ratio of N235 to P350 in the binary extractant. When the volume ratio is 5:1 and 3:1, the extraction efficiency of iron and neodymium is not much different and is at a low level. When the volume ratio is 1:1, 1:3, and 1:5, the separation effect of the two is excellent. Considering the extraction efficiency and separation coefficient, the present invention preferably uses an extractant obtained by mixing N235 and P350 in a volume ratio of 1:1 for subsequent experiments (N235-P350, i.e. NP).

[0145] Example 8

[0146] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0147] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.1 mL of N235 and P350 composite extractant, extract and react for 10 min at room temperature (25°C); the volume ratio of N235 to P350 is 1:1;

[0148] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 7 shown.

[0149] According to the same method as in Example 8, the volumes of the N235 and P350 composite extractants (the volume ratio of N235 and P350 remains unchanged at 1:1) were set to 0.2 mL, 0.3 mL, 0.4 mL, 0.5 mL, and 0.6 mL, respectively; the extraction efficiency and separation coefficient of iron and neodymium were calculated in the same way, and the results were as follows: Figure 7 shown.

[0150] from Figure 7 It can be seen that the extraction efficiency of iron and neodymium gradually increases with the increase of the amount of extractant. When it increases from 0.1mL to 0.4mL, the extraction efficiency of iron increases rapidly, while that of neodymium does not change. When the amount is greater than 0.4mL, the extraction efficiency of both has tended to be stable, so 0.4mL (ie 8vol%) is taken as the optimal amount of extractant.

[0151] Example 9

[0152] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0153] S1, 5 mL of the diluent in Example 5, 25 mL of 260# sulfonated kerosene, and 0.4 mL of the composite extractant of N235 and P350 were mixed, and the extraction reaction was carried out at room temperature (25°C) for 10 min; the volume ratio of N235 to P350 was 1:1; the volume ratio of 260# sulfonated kerosene to the diluent was 5:1;

[0154] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 8 shown.

[0155] Example 10

[0156] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0157] S1, 5 mL of the diluent in Example 5, 15 mL of 260# sulfonated kerosene, and 0.4 mL of the composite extractant of N235 and P350 were mixed, and the extraction reaction was carried out at room temperature (25°C) for 10 min; the volume ratio of N235 to P350 was 1:1; the volume ratio of 260# sulfonated kerosene to the diluent was 3:1;

[0158] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 8 shown.

[0159] Embodiment 11

[0160] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0161] S1. After mixing 5 mL of the diluent in Example 5, 10 mL of 260# sulfonated kerosene, and 0.4 mL of the composite extractant of N235 and P350, the extraction reaction was carried out at room temperature (25°C) for 10 min; the volume ratio of N235 to P350 was 1:1; the volume ratio of 260# sulfonated kerosene to the diluent was 2:1;

[0162] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 8 shown.

[0163] Example 12

[0164] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0165] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.4 mL of the composite extractant of N235 and P350, the extraction reaction was carried out at room temperature (25°C) for 10 min; the volume ratio of N235 to P350 was 1:1; the volume ratio of 260# sulfonated kerosene to the diluent was 1:1;

[0166] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 8 shown.

[0167] Example 13

[0168] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0169] S1. After mixing 15 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 1.2 mL of the composite extractant of N235 and P350, the extraction reaction was carried out at room temperature (25°C) for 10 min; the volume ratio of N235 to P350 was 1:1; the volume ratio of 260# sulfonated kerosene to the diluent was 1:3;

[0170] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Figure 8 shown.

[0171] Figure 8 5:1 corresponds to Example 9, 3:1 corresponds to Example 10, 2:1 corresponds to Example 11, 1:1 corresponds to Example 12, and 1:3 corresponds to Example 13.

[0172] from Figure 8 It can be seen that within different ratio ranges, the extraction efficiency of iron changes little, and the extraction efficiency of neodymium is the smallest when the ratio is 1:1, and the separation effect of the two is the best. Therefore, the volume ratio of 260# sulfonated kerosene to diluent is 1:1 as the optimal volume ratio.

[0173] Embodiment 14

[0174] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0175] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.4 mL of N235 and P350 composite extractant, extract and react at room temperature (25°C) for 1 min; the volume ratio of N235 to P350 is 1:1;

[0176] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Fig. 9 shown.

[0177] According to the same method as in Example 14, the extraction reaction time was set to 3min, 5min, 7min, 10min, 20min, 40min, 60min, and 120min, respectively; the extraction efficiency and separation coefficient of iron and neodymium were calculated in the same way. The results are as follows Fig. 9 shown.

[0178] from Fig. 9 It can be seen that when the reaction time increased from 1 min to 3 min, the extraction efficiency of iron increased from 97.08% to 99.13%, and that of neodymium increased from 7.86% to 8.64%; when the extraction time continued to increase, there was no obvious change, so the extraction time of 3 min was used as the subsequent extraction experiment.

[0179] Embodiment 15

[0180] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0181] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.4 mL of N235 and P350 composite extractants, extract and react for 3 min at 15° C.; the volume ratio of N235 to P350 is 1:1;

[0182] S2. After the extraction reaction, separate and obtain the lower layer liquid; take 2mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the extraction efficiency and separation coefficient of iron and neodymium. The results are as follows: Fig.10 shown.

[0183] According to the same method as in Example 15, the extraction reaction temperature was set to 25°C, 35°C, 45°C, and 55°C, respectively; the extraction efficiency and separation coefficient of iron and neodymium were calculated in the same way. The results are as follows: Fig.10 shown.

[0184] from Fig.10 It can be seen that within the experimental temperature range, as the temperature increases, the extraction efficiency of iron slowly decreases, while that of neodymium slowly increases, and the separation effect of the two becomes worse; since both low and high temperatures require additional investment, room temperature (25°C) is selected as the subsequent experimental temperature.

[0185] Example 16 This example provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0186] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.4 mL of N235 and P350 composite extractants, extract and react for 3 min at 25° C.; the volume ratio of N235 to P350 is 1:1;

[0187] S2, after the extraction reaction, separation is performed to obtain a lower layer liquid and an upper layer liquid;

[0188] S3, add 4 mL of the upper layer liquid and 4 mL of 0.5 mol / L H 2 SO 4 The solution was stripped and reacted at room temperature (25°C) for 60 min;

[0189] S6. After the stripping reaction, separate again to obtain the lower layer liquid; take 2 mL of the lower layer liquid and dilute it 10 times with a dilute nitric acid solution with a mass concentration of 3%. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the stripping efficiency of iron. The result is as follows: Fig.11 shown.

[0190] According to the same method as in Example 16, H 2 SO 4 The solution concentrations were set to 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, and 3.0 mol / L (the volume remained unchanged at 4 mL). The stripping efficiency of iron was calculated in the same way. The results are as follows: Fig.11 shown.

[0191] from Fig.11 It can be seen that when H 2 SO 4 When the concentration of the solution is 1.5 mol / L, the stripping efficiency of iron is close to 80%. 2 SO 4 As the solution concentration continued to increase, the stripping efficiency did not change much, so 1.5 mol / L was taken as the optimal stripping concentration.

[0192] Embodiment 17

[0193] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0194] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.4 mL of N235 and P350 composite extractants, extract and react for 3 min at 25° C.; the volume ratio of N235 to P350 is 1:1;

[0195] S2, after the extraction reaction, separation is performed to obtain a lower layer liquid and an upper layer liquid;

[0196] S3, add 4 mL of the upper layer liquid and 4 mL of 1.5 mol / L H 2 SO 4 Solution, back extraction reaction at 15 ° C for 60 min;

[0197] S6. After the stripping reaction, separate again to obtain the lower layer liquid; take 2 mL of the lower layer liquid and dilute it 10 times with a 3% dilute nitric acid solution. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the stripping efficiency of iron. The results are as follows: Fig.12 shown.

[0198] According to the same method as in Example 17, the stripping reaction temperature was set to 25°C, 35°C, 45°C, and 55°C (the stripping reaction time was unchanged at 60 min), respectively; the stripping efficiency of iron was calculated in the same way, and the results were as follows: Fig.12 shown.

[0199] from Fig.12It can be seen that as the temperature increases, the stripping efficiency also gradually increases, which indicates that the stripping process is an endothermic reaction. Considering that high temperature requires additional investment, room temperature (25°C) is taken as the optimal stripping temperature.

[0200] Embodiment 18

[0201] This embodiment provides a method for extracting and separating iron and neodymium from a leachate, comprising the following steps:

[0202] S1, after mixing 5 mL of the diluent in Example 5, 5 mL of 260# sulfonated kerosene, and 0.4 mL of N235 and P350 composite extractants, extract and react for 3 min at 25° C.; the volume ratio of N235 to P350 is 1:1;

[0203] S2, after the extraction reaction, separation is performed to obtain a lower layer liquid and an upper layer liquid;

[0204] S3, add 4 mL of the upper layer liquid and 4 mL of 1.5 mol / L H 2 SO 4 Solution, back extraction reaction at 25 ° C for 5 min;

[0205] S6. After the stripping reaction, separate again to obtain the lower layer liquid; take 2 mL of the lower layer liquid and dilute it 10 times with a 3% dilute nitric acid solution. Use ICP-OES to detect the concentration of iron and neodymium, and calculate the stripping efficiency of iron. The results are as follows: Fig.13 shown.

[0206] According to the same method as in Example 13, the stripping reaction time was set to 10min, 20min, 40min, 60min, and 120min respectively (the stripping reaction temperature was kept at 25°C); the stripping efficiency of iron was calculated in the same way, and the results were as follows: Fig.13 shown.

[0207] from Fig.13 It can be seen that when the stripping time is increased to 10 min, the stripping efficiency has reached 77%; when it continues to increase to 60 min, the stripping efficiency has reached 80%, and then it no longer increases. Therefore, the present invention selects 60 min as the optimal stripping time.

[0208] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for leaching NdFeB waste, characterized in that: The following steps are involved: The NdFeB waste is added into a citric acid aqueous solution, and the solution is leached at 50-90° C. for 15-240 minutes. After the leaching is completed, a leachate is obtained.

2. The leaching method of NdFeB waste according to claim 1, characterized in that: The concentration of the citric acid aqueous solution is 0.02-1.0 mol / L.

3. The leaching method of NdFeB waste according to claim 1, characterized in that: The solid-liquid ratio of the NdFeB waste material to the citric acid aqueous solution is (5-20) g:1L.

4. The leaching method of NdFeB waste according to claim 1, characterized in that: Add NdFeB waste into citric acid aqueous solution and perform leaching reaction at 80°C for 90 minutes; The concentration of the citric acid aqueous solution is 0.2 mol / L; The solid-to-liquid ratio of the NdFeB waste to the citric acid aqueous solution is 10g:1L.

5. A method for extracting and separating iron and neodymium from a leachate, characterized in that: The following steps are involved: Obtaining a leachate according to any one of claims 1 to 4; The leaching solution and the leaching agent are mixed, and H2O2 solution and the diluent are added and mixed to obtain a diluent; After mixing the diluent, sulfonated kerosene and extractant, perform extraction reaction at 15-55°C for 1-120 minutes; After the extraction reaction, separation is performed to obtain a lower layer liquid and an upper layer liquid; Add H2SO4 solution to the upper liquid layer and conduct back extraction reaction at 15-55°C for 5-120 minutes; After the stripping reaction, separation is performed again to obtain the lower layer liquid.

6. The method for extracting and separating iron and neodymium from a leaching solution according to claim 5, characterized in that: The leaching agent is a 0.2 mol / L citric acid aqueous solution; The diluent is a 0.2 mol / L citric acid aqueous solution; The extractant includes any one of N235, P350, P507, a mixed extractant of N235 and P350, a mixed extractant of N235 and P204, a mixed extractant of N235 and 507, and a mixed extractant of N235 and Cyanex272; The volume ratio of the leaching solution, the leaching agent, and the H2O2 solution is (30-35) mL: (90-95) mL: (10-15) mL; The mass concentration of the H2O2 solution is 30-35%; The ratio of the volume of the diluent to the sum of the volumes of the leaching solution, the leaching agent and the H2O2 solution is (1-2):(1-2).

7. The method for extracting and separating iron and neodymium from a leaching solution according to claim 5, characterized in that: The extractant is a mixed extractant of N235 and P350; The volume ratio of N235 and P350 is (1-5):(1-5); The volume ratio of the diluent, sulfonated kerosene and extractant is (5-15) mL: (5-25) mL: (0.1-1.2) mL.

8. The method for extracting and separating iron and neodymium from a leaching solution according to claim 7, characterized in that: The volume ratio of N235 and P350 is 1:1; The volume ratio of the diluent, sulfonated kerosene, and extractant is 5 mL:5 mL:0.4 mL; The diluent, sulfonated kerosene and extractant were mixed and subjected to extraction reaction at 25°C for 3 minutes.

9. The method for extracting and separating iron and neodymium from a leaching solution according to claim 5, characterized in that: In the step of adding H2SO4 solution to the upper layer liquid and performing back extraction reaction at 15-55°C for 5-120 minutes; the concentration of the H2SO4 solution is 0.5-3.0 mol / L; the volumes of the upper layer liquid and the H2SO4 solution are 4 mL:4 mL.

10. The method for extracting and separating iron and neodymium from a leaching solution according to claim 9, characterized in that: H2SO4 solution was added to the upper liquid layer, and the stripping reaction was carried out at 25°C for 60 minutes. The concentration of the H2SO4 solution was 1.5 mol / L.

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