Functionalized resin for recovering neodymium from rare earth ore leaching solution and preparation method thereof

Abstract

The application discloses a functionalized resin for recovering neodymium from rare earth ore leaching solution and a preparation method thereof, and belongs to the technical field of rare earth separation. ’ ,N ’ The application first prepares an amino functionalized resin by reacting chloromethylated resin with an excess of an aminating agent; second, the amino resin is reacted with N,N-dioctyl-2-chloroacetamide to immobilize a core coordination structure through an amide bond, forming a N,N,N ’ ,N ’ -tetraoctyl diglycolamide (DOTGA) structure; finally, the residual amino groups in the resin skeleton are directly reacted with a dialkyl phosphite to introduce phosphonate functional groups. The synthesis route is efficient, mild and low in cost, and the obtained resin combines the synergistic coordination advantages of amide and phosphonate, exhibits extremely high adsorption capacity, selectivity and cyclic stability for neodymium ions in a complex environment, and is suitable for efficiently and economically recovering neodymium from a complex acidic feed liquid.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology and relates to a functionalized resin for recovering neodymium from rare earth ore leaching solution and its preparation method. Background Technology

[0002] Rare earth elements are indispensable key raw materials in modern industry and high-tech fields, and are known as "industrial vitamins." Among them, neodymium (Nd) is a key raw material for the preparation of neodymium-iron-boron permanent magnet materials, and its recycling is particularly important. However, the physicochemical properties of rare earth elements are extremely similar, making their separation very difficult, especially the separation of adjacent rare earth elements. Among light rare earth elements, praseodymium (Pr) and neodymium (Nd) have very similar ionic radii, and are recognized as one of the most difficult rare earth element pairs to separate.

[0003] Traditional rare earth extraction methods mainly include stepwise extraction, ion exchange, and solvent extraction. Among these, solvent extraction is the most widely used in rare earth industrial production and is currently the most commonly used technique in rare earth separation. However, traditional solvent extraction has many problems: due to differences in extractant performance, the separation coefficient is low, requiring hundreds or thousands of extraction stages, while also resulting in long processes, high reagent consumption, and high costs; some extractants easily form solid precipitates with high-valence metal ions, leading to emulsification and affecting stable operation; and the functional group structure design of existing resins in ion exchange methods is not optimized enough, making it difficult to achieve highly selective adsorption and efficient separation of specific target ions, thus limiting its application in complex environments.

[0004] To address the aforementioned issues, researchers have developed various extraction methods, including the preparation of novel extractants and the optimization of extraction processes, aiming to further improve the separation effect of extractants. For example, Chinese patent application CN110699546A discloses an extractant, its preparation method, and its application. This invention uses a reaction between a bisphenol compound and a haloacetate, followed by acidification, to obtain the corresponding extractant. This extractant exhibits higher loading capacity, high precipitation efficiency, and larger rare earth precipitate size, which is beneficial for the separation of rare earth extraction complexes and the aqueous phase. However, in practical applications, this invention still faces the challenge of further optimizing the extractant loading and the particle size of the rare earth element precipitate. Chinese patent application CN115491526A discloses a method for extracting and separating rare earth elements using a non-aqueous solvent extraction system. This method employs a non-aqueous extraction system composed of a highly polar organic phase (such as polyethylene glycol) mixed with water, and a low-polarity organic phase (such as dimethylheptyl methylphosphonate diluted with kerosene). Compared to traditional solvent extraction, the reduction in water molecules significantly weakens the hydration of rare earth ions, exposing those previously encapsulated in a hydration layer and thus improving the coordination efficiency between the extractant molecules and rare earth ions. However, this invention still requires further optimization of the extraction conditions to improve extraction efficiency and separation effect. According to relevant research reports, N,N,N',N'-tetraoctyldiglycolamide (TODGA) extractant, as a novel extractant, has good separation effect in the extraction and separation of neodymium. However, due to the problems of long process, large reagent consumption and high cost when using solvent extraction alone, researchers have combined the extractant with resin method to prepare extraction resin. Although the utilization rate of extractant is improved, the combination between extractant and resin is only a simple physical combination, and there are still some limitations in terms of stability.

[0005] Based on the above existing neodymium separation processes, the current extraction technology has the following drawbacks: 1. Traditional solvent extraction methods have low separation coefficients and require hundreds or thousands of extraction stages, resulting in long processes, high reagent consumption, and high costs, which affect the separation efficiency of rare earth elements. 2. Extraction resins have some limitations in terms of single function and low stability, making it difficult to meet the separation requirements under complex process conditions; 3. Traditional solid-phase extraction resin preparation methods have problems such as complex operation, high cost, and environmental pollution, which are not conducive to industrial production and widespread application. 4. The functional group structure design of existing resins is not optimized enough, making it difficult to achieve highly selective adsorption and efficient separation of specific target ions, which limits their application effect in complex environments. Therefore, how to solve the problems of low separation efficiency, long extraction process, high reagent consumption, high cost and poor stability of extractant in existing neodymium technology, and how to develop a new type of separation material based on resin skeleton to improve the separation efficiency and stability of rare earth elements and achieve efficient extraction of neodymium, has become an important technical problem to be solved by those skilled in the art. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a functionalized resin for recovering neodymium from rare earth ore leachate and its preparation method, thereby solving the technical problems of low neodymium element separation efficiency, long extraction process, high reagent consumption, high cost and poor extractant stability in the prior art.

[0007] This invention is achieved through the following technical solution: A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Step 1: Mix the chlorine balls with the amination reagent, stir to allow for one swelling, and after the first swelling is completed, perform a heating reaction to obtain the amino-functionalized resin; Step 2: The amino-functionalized resin is placed in a second solvent for secondary swelling. After the secondary swelling is completed, N,N-dioctyl-2-chloroacetamide solution is slowly added dropwise to the system. An inert gas is introduced under stirring conditions to carry out a secondary heating reaction. TODGA groups are introduced through amide bonds to obtain PS-TODGA-NH2 resin. Step 3: Add PS-TODGA-NH2 resin to the fourth solvent, and add acid-binding agent and dialkyl phosphite, preferably diethyl phosphite. Stir and swell three times. After the three swellings are completed, add oxidant and perform three heating reactions. Use the residual amino groups in the resin to introduce phosphonic acid ester groups to obtain the functionalized resin for neodymium recovery.

[0008] Preferably, in step 1, the ratio of the amount of chlorinated sphere to the amination reagent is 1g:(5-8)mL.

[0009] Preferably, in step 1, the reaction temperature during the first heating reaction is 110-150℃, and the reaction time is 15-25h.

[0010] Preferably, in step 2, the mass ratio of the amino-functionalized resin to the N,N-dioctyl-2-chloroacetamide solution is 1:(0.1-0.4), and the mass concentration of the N,N-dioctyl-2-chloroacetamide solution is 20%-60%.

[0011] Preferably, in step 2, during the secondary heating reaction, the reaction temperature is 25-60℃ and the reaction time is 3-8h.

[0012] Preferably, in step 3, the ratio of the amount of PS-TODGA-NH2 resin to dialkyl phosphite is 1g:(2.5-6)mL, and the dialkyl phosphite is at least one selected from dimethyl phosphite, diethyl phosphite, di-n-propyl phosphite, diisopropyl phosphite, di-n-butyl phosphite, diisobutyl phosphite, and di-tert-butyl phosphite.

[0013] Preferably, in step 3, the mass ratio of the PS-TODGA-NH2 resin to the oxidant is 1:(0.5-2).

[0014] Preferably, in step 3, the reaction temperature during the three heating reactions is 40-60℃ and the reaction time is 12-24h.

[0015] A functionalized resin for recovering neodymium from rare earth ore leaching solution is prepared by the above method; the matrix of the functionalized resin is a polystyrene matrix, and amide groups and phosphonate groups are grafted onto the polystyrene matrix. The amide group is formed by the reaction of N,N-dioctyl-2-chloroacetamide with an amino group; The phosphonate group is formed by the reaction of a dialkyl phosphite with an amino group.

[0016] The above-mentioned functionalized resin for recovering neodymium from rare earth ore leachate is used in neodymium recovery.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solutions. The resin prepared by this method has TODGA-like amide groups and phosphonate groups densely grafted onto the resin framework, forming specific adsorption sites for neodymium ions. This significantly improves ion selectivity and adsorption capacity, thereby greatly shortening the separation process and reducing the number of separation stages. Compared to traditional liquid-liquid extraction, which requires large amounts of volatile organic solvents, the solid-phase resin method of this invention consumes extremely low amounts of reagents and has a simple process, effectively reducing production costs. More importantly, the functional groups are fixed on the carrier through chemical bonding, fundamentally avoiding the loss and degradation of the extractant in the aqueous phase, solving the problem of poor extractant stability, and ensuring the performance stability of the resin during long-term recycling. This provides technical support for the efficient and green recovery of rare earth resources.

[0018] Furthermore, in step 1, the ratio of the amount of chlorine sphere to the amination reagent is 1g:(5-8)mL. This ratio ensures that the amination reagent can fully penetrate and react inside the chlorine sphere, which not only ensures the high grafting rate of the primary amine group, but also avoids reagent waste, providing sufficient reaction sites for subsequent functionalization reactions, and is the basis for achieving high adsorption capacity.

[0019] Furthermore, in step 1, during the first heating reaction, the reaction temperature is 110-150℃ and the reaction time is 15-25h. This high-temperature and long-time reaction condition can effectively overcome steric hindrance, drive the amination reaction to proceed completely, and ensure that the chlorine groups on the chlorine bead skeleton are fully converted into active primary amine groups, thereby improving the reactivity of the resin and the efficiency of subsequent functionalization.

[0020] Furthermore, in step 2, the mass ratio of the amino-functionalized resin to the N,N-dioctyl-2-chloroacetamide solution is 1:(0.1-0.4), and the mass concentration of the N,N-dioctyl-2-chloroacetamide solution is 20%-60%. This ratio and concentration range can precisely control the grafting density of the TODGA-like functional groups, ensuring that the resin has excellent selective complexing ability, while preventing side reactions or pore blockage caused by excessive monomer, and maintaining the good mass transfer performance of the resin.

[0021] Furthermore, in step 2, during the secondary heating reaction, the reaction temperature is 25-60℃ and the reaction time is 3-8h. These mild reaction conditions are sufficient to drive the amidation coupling reaction, while effectively avoiding the destruction of the resin skeleton or the already formed amide bonds by high temperature, thus ensuring the high selectivity of the functionalization reaction and the integrity of the resin structure.

[0022] Furthermore, in step 3, the ratio of PS-TODGA-NH2 resin to dialkyl phosphite is 1g:(2.5-6)mL. This ratio ensures the full introduction of phosphonate groups, forming a synergistic effect with TODGA-like groups, further enhancing the adsorption capacity for neodymium ions, and optimizing the dual-functional properties of the resin.

[0023] Furthermore, in step 3, the mass ratio of the PS-TODGA-NH2 resin to the oxidant is 1:(0.5-2). This ratio range can efficiently promote the phosphonate esterification reaction, ensure that the residual amino groups are completely converted, and avoid excessive oxidation or cross-linking of the resin skeleton that may be caused by excessive oxidant, thus ensuring the safety and controllability of the reaction.

[0024] Furthermore, in step 3, the reaction temperature during the three heating reactions is 40-60℃ and the reaction time is 12-24h. This combination of parameters provides sufficient motive force and time for the phosphonate esterification reaction, ensuring that the dialkyl phosphite can fully react with the residual amino group to form a stable phosphonate ester group, thereby maximizing the final adsorption performance and chemical stability of the resin. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic flowchart of a method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to the present invention. Detailed Implementation

[0027] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions mentioned in the specification are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0029] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0030] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0031] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0032] like Figure 1 As shown, this invention provides a method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution, comprising the following steps: Step 1, Preparation of amino-functionalized resin: Chloride balls are mixed with amination reagent, stirred and swollen once, and after the swelling is completed, a heating reaction is carried out to obtain amino-functionalized resin. The above process is as follows: Step 101: Place the dried polystyrene macroporous chlorospheres (hereinafter referred to as "chlorospheres") in a reaction vessel, add the amination reagent, and stir to allow for one swelling. Step 102: After the swelling is completed once, a heating reaction is carried out. After the reaction is completed, the reaction mixture is cooled to room temperature, the mother liquor is filtered, the solid resin is separated, the resin is thoroughly washed with the first solvent, and finally washed with water until the washing liquid is neutral. The resin is then dried to constant weight to obtain amino-functionalized resin. The chlorine spheres contain ≥18% chlorine, the amination reagent is at least one selected from ethylenediamine, 1,3-propanediamine, and 1,6-hexanediamine, and the swelling time is 2-6 hours. The ratio of chlorinated globules to amination reagent is 1 g: (5-8) mL; During the first heating reaction, the reaction temperature is 110-150℃ and the reaction time is 15-25h; The first solvent is at least one of methanol, ethanol, and methylal; Step 2, Preparation of functionalized coupling resin: The amino-functionalized resin is placed in a second solvent for secondary swelling. After the secondary swelling is completed, N,N-dioctyl-2-chloroacetamide solution is slowly added dropwise to the system. An inert gas is introduced under stirring conditions to carry out a secondary heating reaction to obtain PS-TODGA-NH2 resin. The above process is as follows: Step 201: Take the amino-functionalized resin prepared above and disperse it in a second solvent for secondary swelling; Step 202: After the second swelling is completed, slowly add N,N-dioctyl-2-chloroacetamide solution dropwise to the system; Step 203: Under stirring conditions, nitrogen or inert gas is introduced for protection, and a second heating reaction is carried out; Step 204: After the second heating reaction is completed, filter and collect the resin product. Use a third solvent to post-treat the resin product to remove unreacted raw materials and by-products. Finally, wash with deionized water until neutral to obtain solid resin, namely PS-TODGA-NH2 resin.

[0033] The second solvent is at least one of dichloromethane, tetrahydrofuran, acetonitrile, and 1,4-dioxane; The ratio of the amino-functionalized resin to the second solvent is 1g:(5-10)mL, and the secondary swelling time is 4-8h. The mass ratio of the amino-functionalized resin to the N,N-dioctyl-2-chloroacetamide solution is 1:(0.1-0.4). Before addition, the N,N-dioctyl-2-chloroacetamide is dissolved in a second solvent to prepare a solution with a mass concentration of 20%-60%, i.e., the mass concentration of the N,N-dioctyl-2-chloroacetamide solution is 20%-60%. The reaction temperature of the amino-functionalized resin with N,N-dioctyl-2-chloroacetamide is 25-60℃ and the reaction time is 3-8h. That is, during the second heating reaction, the reaction temperature is 25-60℃ and the reaction time is 3-8h. The third solvent is at least one of N,N-dimethylformamide, methanol, ethanol, methyl acetal, tetrahydrofuran, and dichloromethane; Step 3, Preparation of phosphonate esterified resin: PS-TODGA-NH2 resin is added to the fourth solvent, along with an acid-binding agent and dialkyl phosphite. The mixture is stirred and swollen three times. After the three swellings are completed, an oxidant is added and the mixture is heated three times to obtain the functionalized resin used for neodymium recovery. The dialkyl phosphite is at least one selected from dimethyl phosphite, diethyl phosphite, di-n-propyl phosphite, diisopropyl phosphite, di-n-butyl phosphite, diisobutyl phosphite, and di-tert-butyl phosphite.

[0034] The above process is as follows: Step 301: Add the PS-TODGA-NH2 resin with residual amino groups to the fourth solvent, add the acid-binding agent and the functionalizing reagent dialkyl phosphite required for the phosphonate esterification reaction, and stir to allow for three swelling cycles. After the three swelling cycles are complete, under ice bath cooling and stirring, slowly add the oxidant, controlling the temperature to be below 10°C. After the addition is complete, remove the ice bath and perform three heating reactions, i.e., the phosphonate esterification reaction. The acid-binding agent is used in the phosphonate esterification reaction. This step utilizes the residual amino groups (-NH2) in the resin skeleton to react with the dialkyl phosphite. However, acidic byproducts are usually generated during this reaction. If these acidic substances accumulate, they will inhibit the reaction and even damage the reaction environment. Therefore, the main role of adding the acid-binding agent potassium carbonate is to neutralize the acidic byproducts and promote the forward reaction. Step 302: After the three heating reactions are completed, the resin is thoroughly washed with tetrahydrofuran, methanol and water in sequence to finally obtain the finished product PS-TODGA-P(O)(OEt)2 resin, which is the functionalized resin used for neodymium recovery. The ratio of PS-TODGA-NH2 resin to dialkyl phosphite is 1g:(2.5-6)mL, and the swelling time for three cycles is 5-10h. The mass ratio of the PS-TODGA-NH2 resin to the acid-binding agent is 1:(0.1-0.6); The fourth solvent is at least one of anhydrous tetrahydrofuran, anhydrous toluene, and anhydrous dichloromethane; the mass-to-volume ratio of the PS-TODGA-NH2 resin to the fourth solvent is 1 g:(3.5-7) mL. The oxidant is at least one of carbon tetrachloride and hexachloroethane, and the mass ratio of PS-TODGA-NH2 resin to oxidant is 1:(0.5-2). During the three heating reactions, the reaction temperature was 40-60℃ and the reaction time was 12-24h.

[0035] This invention provides a method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solutions. This functionalized resin is effective against neodymium ions (Nd). 3+ This invention, employing a two-step synthesis method using polystyrene macroporous chloroacetamide spheres as a matrix, involves "chloroacetamide sphere amination-functionalization intermediate coupling," followed by direct phosphonate esterification modification to construct a synergistic coordination structure. First, chloroacetamide spheres are reacted with excess amination reagent to prepare an amino-functionalized resin. Second, this amino-functionalized resin is reacted with N,N-dioctyl-2-chloroacetamide to immobilize the core coordination structure via amide bonds. Finally, the residual amino groups in the resin backbone are directly reacted with dialkyl phosphite esters to introduce phosphonate ester functional groups. This synthetic route is efficient, mild, and inexpensive. The resulting resin combines the synergistic coordination advantages of amides and phosphonates, exhibiting extremely high adsorption capacity, selectivity, and cycling stability for neodymium ions in strongly acidic environments, making it suitable for the efficient and economical recovery of neodymium from complex acidic solutions.

[0036] Specifically, the present invention has the following advantages: 1. Strong Bonding and Excellent Stability: This invention fundamentally solves the problem of extractant leaching in physical impregnation methods by covalently immobilizing the core functional groups through the formation of chemically stable amide bonds. Crucially, the introduced N,N-dioctylamide structure has a large molecular size, forming a TODGA-like structure that creates a steric hindrance layer on the resin surface. This layer inhibits non-specific adsorption through hydrophobic interactions, significantly improving selectivity for Nd:d: and the phosphoramide bond formed through direct condensation reaction exhibits high stability. This dual chemical bonding mechanism of macromolecular surface modification and small molecule internal filling significantly improves the resin's stability in complex operating environments and long-term cycling, greatly extending its service life and reliability.

[0037] 2. The synthetic route is efficient, economical, and environmentally friendly: The core synthetic process employs a two-step method of "chlorosphere amination-functionalization intermediate coupling," which is simple to operate, operates under mild conditions, and is easy to scale up for production. Based on this, a phosphonate modification step is introduced, utilizing the residual amino groups in the resin to react with inexpensive and readily available dialkyl phosphites. The phosphonate groups introduced in this step have small molecular weights and low steric hindrance, allowing them to diffuse smoothly into the deep pores of the resin matrix, achieving comprehensive functionalization of the resin "from the surface to the interior." This further enhances the synergistic coordination effect with target ions and significantly improves the extraction efficiency.

[0038] 3. Complete coordination structure and synergistic enhancement: This invention constructs a TODGA-like "carbonyl-methylene" key coordination environment on the resin through the -CO-CH2- structural unit, exhibiting excellent basic complexation ability for trivalent lanthanide ions. Based on this, a unique dual enhancement mechanism is formed, specifically: Surface selectivity: The larger molecular weight dioctylamide structure is mainly distributed on the resin surface. Its hydrophobic long chain and specific coordination configuration can effectively shield coexisting interfering ions, providing a highly selective recognition interface for neodymium ions.

[0039] High internal capacity: The smaller molecular weight phosphonate groups (P=O) can enter the deep pores of the resin, serving as stronger "hard base" coordination sites. They form intramolecular coordinating coordination with the original amide oxygen, significantly increasing the effective adsorption site density per unit volume of resin.

[0040] This synergistic mechanism of "surface selective recognition and internal high-density capture" significantly enhances the targeting of neodymium ions (Nd). 3+ The affinity and total adsorption capacity of the adsorption are significantly improved, especially under high acidity conditions.

[0041] 4. Wide applicability and simple, efficient process: This functionalized resin can be directly used to selectively separate and enrich neodymium from complex acidic leachates containing multiple coexisting ions such as iron, calcium, and aluminum (e.g., leachates from waste magnets) through a simple dynamic adsorption process. Thanks to the surface selectivity provided by the macromolecular amide bonds and the high internal capacity provided by the small-molecule phosphonate esters, the resin maintains excellent separation efficiency even in complex feed environments. This process avoids the large-scale use of organic solvents, making it more environmentally friendly, while simultaneously improving the efficiency and economic benefits of rare earth secondary resource recovery.

[0042] 5. Excellent chemical stability and low recycling cost: Because all functional groups are firmly linked by covalent bonds, this resin exhibits excellent chemical stability and can withstand multiple acid and alkali regenerations. The dual-functionalization design ensures the resin's stability during multiple cycles; the large amide bonds on the surface are not easily detached due to mechanical wear, while the internal small phosphonate esters continuously provide high capacity. This synergistic coordination structure guarantees high capacity even under high acid conditions, reducing the frequency of resin replacement, further lowering long-term operating costs, and improving resource utilization efficiency.

[0043] In addition, the present invention also discloses a resin material for neodymium recovery prepared by the above method. This resin material organically combines high efficiency, selectivity, stability, economy and environmental protection, providing a revolutionary solid-phase solution for the separation of neodymium in rare earth elements, and fundamentally improving many drawbacks of traditional solvent extraction processes.

[0044] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0045] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0046] Example 1 A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 600mL of ethylenediamine solution and stir to swell for 4h. After swelling, raise the temperature to 110℃ to start the reaction. After reacting for 20h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with methanol, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the prepared amino-functionalized resin and 480mL of dichloromethane and add them to a reaction vessel. Stir and swell for 4h. After swelling, slowly add a 30% dichloromethane solution prepared from 16g of N,N-dioctyl-2-chloroacetamide to the system. Under stirring, purge with nitrogen for protection and heat to 30℃ for 8h. After the reaction, filter and collect the resin product. Post-treat the resin product with methanol to remove unreacted raw materials and byproducts. Finally, wash with deionized water until neutral and dry to obtain solid resin (denoted as PS-TODGA-NH2).

[0047] Weigh 50g of PS-TODGA-NH2 resin with residual amino groups and 200mL of anhydrous dichloromethane into a reaction vessel, add 15g of potassium carbonate and 225mL of diethyl phosphite, stir and swell for 6 hours, then slowly add 50g of carbon tetrachloride dropwise while cooling and stirring in an ice bath, controlling the temperature to be below 10℃. After the addition is complete, remove the ice bath, raise the temperature to 45℃, and react for 20 hours. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product PS-TODGA-P(O)(OEt)2 resin.

[0048] Example 2 A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 500mL of 1,3-propanediamine solution and stir to swell for 6h. After swelling, raise the temperature to 130℃ to start the reaction. After reacting for 25h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with ethanol, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the amino-functionalized resin prepared above and add 800mL of acetonitrile to a reaction vessel and stir to swell for 5h. After swelling, slowly add a 20% acetonitrile solution prepared from 32g of N,N-dioctyl-2-chloroacetamide dropwise to the system. Under stirring, purge with an inert gas and heat to 60℃ for 3h. After the reaction is complete, filter and collect the resin product. Post-treat the resin product with ethanol to remove unreacted raw materials and byproducts. Finally, wash with deionized water until neutral and dry to obtain solid resin (denoted as PS-TODGA-NH2).

[0049] Weigh 50g of PS-TODGA-NH2 resin with residual amino groups and 300mL of anhydrous tetrahydrofuran into a reaction vessel, add 25g of potassium carbonate and 125mL of diethyl phosphite, stir and swell for 8 hours, then slowly add 25g of hexachloroethane dropwise while cooling and stirring in an ice bath, controlling the temperature to be below 10℃. After the addition is complete, remove the ice bath, raise the temperature to 60℃, and react for 12 hours. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product PS-TODGA-P(O)(OEt)2 resin.

[0050] Example 3 A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 600mL of 1,6-hexanediamine solution and stir to swell for 3h. After swelling, raise the temperature to 150℃ to start the reaction. After reacting for 24h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with ethanol, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the amino-functionalized resin prepared above and add 400mL of tetrahydrofuran to a reaction vessel and stir to swell for 4h. After swelling, slowly add a 40% tetrahydrofuran solution prepared with 24g of N,N-dioctyl-2-chloroacetamide dropwise to the system. Under stirring, purge with an inert gas (such as nitrogen) for protection and heat to 55℃ for 4h. After the reaction is complete, filter and collect the resin product. Post-treat the resin product with methyl acetal to remove unreacted raw materials and by-products. Finally, wash with deionized water until neutral and dry to obtain solid resin (denoted as PS-TODGA-NH2).

[0051] Weigh 50g of PS-TODGA-NH2 resin with residual amino groups and 200mL of anhydrous tetrahydrofuran into a reaction vessel, add 30g of potassium carbonate and 200mL of diethyl phosphite, stir and swell for 10h, then slowly add 40g of carbon tetrachloride dropwise while cooling and stirring in an ice bath, controlling the temperature to be below 10℃. After the addition is complete, remove the ice bath, raise the temperature to 40℃, and react for 24h. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product PS-TODGA-P(O)(OEt)2 resin.

[0052] Example 4 A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 800mL of 1,3-propanediamine solution and stir to swell for 2h. After swelling, raise the temperature to 120℃ to start the reaction. After reacting for 18h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with methanol, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the prepared amino-functionalized resin and 640mL of dichloromethane and add them to a reaction vessel. Stir and swell for 8h. After swelling, slowly add a 40% dichloromethane solution prepared from 8g of N,N-dioctyl-2-chloroacetamide to the system. Under stirring, purge with nitrogen for protection and heat to 25℃ for 8h. After the reaction, filter and collect the resin product. Post-treat the resin product with ethanol to remove unreacted raw materials and byproducts. Finally, wash with deionized water until neutral and dry to obtain solid resin (denoted as PS-TODGA-NH2).

[0053] Weigh 50g of PS-TODGA-NH2 resin with residual amino groups and 350mL of anhydrous toluene into a reaction vessel, add 20g of potassium carbonate and 250mL of diethyl phosphite, stir and swell for 8 hours, then slowly add 100g of hexachloroethane dropwise while cooling and stirring in an ice bath, controlling the temperature to be below 10℃. After the addition is complete, remove the ice bath, raise the temperature to 55℃, and react for 15 hours. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product PS-TODGA-P(O)(OEt)2 resin.

[0054] Example 5 A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 700mL of ethylenediamine solution and stir to swell for 4h. After swelling, raise the temperature to 110℃ to start the reaction. After reacting for 15h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with methylal, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the prepared amino-functionalized resin and 640mL of tetrahydrofuran and add them to a reaction vessel. Stir and swell for 8h. After swelling, slowly add a 50% tetrahydrofuran solution prepared with 16g of N,N-dioctyl-2-chloroacetamide to the system. Under stirring, purge with an inert gas and heat to 50℃ for 5h. After the reaction, filter and collect the resin product. Post-treat the resin product with ethanol to remove unreacted raw materials and byproducts. Finally, wash with deionized water until neutral and dry to obtain solid resin (denoted as PS-TODGA-NH2).

[0055] Weigh 50g of PS-TODGA-NH2 resin with residual amino groups and 250mL of anhydrous dichloromethane into a reaction vessel, add 5g of potassium carbonate and 175mL of diethyl phosphite, stir and swell for 5h, then slowly add 60g of carbon tetrachloride dropwise while cooling and stirring in an ice bath, controlling the temperature to be below 10℃. After the addition is complete, remove the ice bath, raise the temperature to 50℃, and react for 18h. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product PS-TODGA-P(O)(OEt)2 resin.

[0056] Example 6 A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution includes the following steps: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 600mL of ethylenediamine solution and stir to swell for 5h. After swelling, raise the temperature to 115℃ to start the reaction. After reacting for 20h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with methyl acetal, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the amino-functionalized resin prepared above and 480mL of 1,4-dioxane into a reaction vessel and stir to swell for 6h. After swelling, slowly add a 60% 1,4-dioxane solution prepared with 24g of N,N-dioctyl-2-chloroacetamide dropwise to the system. Under stirring, nitrogen gas is introduced for protection, and the temperature is raised to 35℃ for 6h. After the reaction is completed, filter and collect the resin product. The resin product is post-treated with methanol to remove unreacted raw materials and by-products. Finally, wash with deionized water until neutral and dry to obtain solid resin (denoted as PS-TODGA-NH2).

[0057] Weigh 50g of PS-TODGA-NH2 resin with residual amino groups and 175mL of anhydrous toluene into a reaction vessel, add 25g of potassium carbonate and 300mL of diethyl phosphite, stir and swell for 6 hours, then slowly add 75g of hexachloroethane dropwise while cooling and stirring in an ice bath, controlling the temperature to be below 10℃. After the addition is complete, remove the ice bath, raise the temperature to 55℃, and react for 15 hours. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product PS-TODGA-P(O)(OEt)2 resin.

[0058] Comparative Example 1 This comparative example only involves the coupling reaction of the matrix resin, specifically: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 600mL of ethylenediamine solution and stir to swell for 4h. After swelling, raise the temperature to 110℃ to start the reaction. After reacting for 20h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with methanol, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 80g of the prepared amino-functionalized resin and 480mL of dichloromethane and add them to a reaction vessel. Stir and swell for 4h. After swelling, slowly add a 30% dichloromethane solution prepared from 16g of N,N-dioctyl-2-chloroacetamide dropwise to the system. Under stirring, purge with an inert gas (such as nitrogen) for protection and heat to 30℃ for 8h. After the reaction, filter and collect the resin product. Post-treat the resin product with methanol to remove unreacted raw materials and byproducts. Finally, wash with deionized water until neutral to obtain the finished resin (denoted as D1-PS-TODGA-NH2).

[0059] Comparative Example 2 This comparative example only involves the phosphorylation reaction of the matrix resin, specifically: Weigh 100g of dried chlorine beads (commercially available D301 chlorine beads, chlorine content 18.5%) and place them in a reaction vessel. Add 600mL of ethylenediamine solution and stir to swell for 4h. After swelling, raise the temperature to 110℃ to start the reaction. After reacting for 20h, cool the reaction mixture to room temperature, filter the mother liquor, separate the solid resin, wash the resin thoroughly with methanol, and finally wash with water until the washing liquid is neutral. Dry the resin to constant weight to obtain amino-functionalized resin. Weigh 50g of amino-functionalized resin and 200mL of anhydrous dichloromethane and add them to the reaction vessel. Add 15g of potassium carbonate and 225mL of diethyl phosphite. After stirring and swelling for 6 hours, slowly add 50g of carbon tetrachloride dropwise while cooling and stirring in an ice bath, keeping the temperature below 10℃. After the addition is complete, remove the ice bath and raise the temperature to 45℃. React for 20 hours. After the reaction is complete, wash the resin thoroughly with tetrahydrofuran, methanol, and water in sequence to obtain the final product D2-PS-P(O)(OEt)2 resin.

[0060] As can be seen from the above embodiments, in the six sets of embodiments designed in this invention, amide groups (TODGA) and phosphate ester groups (P(O)(OEt)2) were successfully grafted onto the amino-functionalized resin backbone through a two-step chemical modification process, thus realizing the preparation of the target bifunctional resin. The properties of the resins obtained in the above embodiments and comparative examples were tested, and the test results are shown in Table 1. Table 1. Resin performance indicators for each embodiment and comparative example.

[0061] First, the resin exchange capacity was tested according to GB / T 8144-2008 standard. The test results showed that all PS-TODGA-NH2 intermediates in the examples exhibited significant amide exchange capacity (0.37-1.38 mmol / g). Simultaneously, the weak base exchange capacity of the resin was tested according to GB / T 5760-2000 standard. The results showed that its primary amine exchange capacity was significantly lower than that of the initial amino-functionalized resin (~5.2 mmol / g) (3.74-4.98 mmol / g), indicating that some primary amine functional groups had reacted with the TODGA reagent and converted into amide structures. Second, the weak base exchange capacity of the resin was tested according to GB / T 5760-2000 standard. The results showed that the primary amine exchange capacity of the final resin PS-P(O)(OEt)2 obtained after phosphate esterification was reduced to an extremely low level (0.02-0.11 mmol / g), indicating that the remaining primary amines were almost completely converted. Meanwhile, the product PS-P(O)(OEt)2 still retains the amide exchange capacity (0.39-1.35 mmol / g) corresponding to the intermediate, indicating that the phosphorylation reaction is selective and does not destroy the formed amide bonds. The final resin PS-P(O)(OEt)2 maintains a high total exchange capacity, further confirming the effective introduction of functional groups and structural integrity.

[0062] The data characteristics of Comparative Example 1 (amidation only) and Comparative Example 2 (phosphoesterification only) showed systematic differences from those of the Example Group. In particular, the resin in Comparative Example 2 that was directly phosphoesterified without amidation had a significantly higher primary amine residual exchange capacity (0.25 mmol / g) than all the Examples. This, in turn, confirms the necessity and effectiveness of the two-step grafting strategy adopted in the Examples.

[0063] In summary, Examples 1-6 successfully completed the continuous functionalization from amino-functionalized resin to PS-TODGA-NH2 and then to PS-P(O)(OEt)2. The two target groups, amide and phosphate ester, were grafted into the resin skeleton. The differences in capacity between different examples mainly reflect subtle differences in the degree of grafting reaction or the optimization of conditions, but all examples have confirmed the feasibility of the synthetic route of the present invention.

[0064] To verify the adsorption effect of the resin prepared in this invention on neodymium, resin samples prepared in Examples 1-6 and Comparative Examples 1-2 were used to adsorb neodymium from rare earth ore leaching solutions. After adsorption, the resin was desorbed using acid. The experimental results are shown in Table 2. Table 2 Comparison of Nd:D resin adsorption and desorption effects in each embodiment and comparative example

[0065] As can be seen from the table above, the resin samples prepared in the embodiments of the present invention exhibit excellent adsorption and desorption effects in the adsorption and separation of neodymium.

[0066] To further highlight the technical advantages of the covalent immobilization strategy of this invention, the following comparative experiment was set up: N,N-dioctyl-2-chloroacetamide (DCA, representing the macromolecular amide structure on the resin surface) and diethyl phosphite (DEP, representing the small molecule phosphonate structure inside the resin) were simply mixed in the organic phase in the same proportion to construct a liquid-phase co-extraction system to simulate the synergistic effect of the two functional groups in the free state.

[0067] Comparative experimental conditions: Aqueous phase: Contains Nd 3+ An acidic solution with an initial concentration of 1.0 × 10⁻⁶. -3 mol / L, pH=3.0; Organic phase: DCA and DEP dissolved in n-heptane at a molar ratio of 2:1, with a total concentration of 0.10 mol / L; Extraction ratio: Organic phase: Aqueous phase = 1:1 (volume ratio); Extraction temperature: 25±0.5°C; Extraction time: 120 minutes (oscillation, standing for phase separation).

[0068] Experiments have verified that the liquid-phase blending extraction system effectively removes Nd during the initial extraction. 3+ The single extraction rate is approximately 31%. However, after repeated use (without replenishing fresh extractant), DCA and DEP are gradually lost due to dissolution in the organic phase and partial entrainment in the aqueous phase, resulting in a significant decrease in extraction capacity: after multiple cycles, the extraction rate drops to below 45% of the initial rate, and emulsification occurs in the organic phase, making phase separation difficult.

[0069] In contrast, the resin immobilized in this invention, under the same number of cycles, has functional groups immobilized through covalent bonds with almost no desorption, maintains a stable adsorption capacity, and the resin particles are intact and unbroken, making it easy to regenerate and reuse.

[0070] The above comparison results fully demonstrate that physical blending extraction cannot avoid extractant loss, while the present invention immobilizes two functional groups on the same resin skeleton through covalent bonds, which not only retains the synergistic coordination effect of amide and phosphonate, but also endows the material with excellent cycle stability and ease of operation, and has significant practical value in the field of rare earth separation.

[0071] In summary, this invention utilizes a three-step strategy of molecular design, covalent immobilization, and synergistic modification to prepare a neodymium adsorption resin exhibiting high selectivity, high stability, and high acid tolerance. Its process is simple, low-cost, and environmentally friendly, providing a disruptive solid-phase solution for recovering neodymium from complex rare earth leachates (especially secondary resources). It is expected to supplement or replace existing solvent extraction processes and has significant industrial application prospects.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution, characterized in that, Includes the following steps: Step 1: Mix the chlorine balls with the amination reagent, stir to allow for one swelling, and after the first swelling is completed, perform a heating reaction to obtain the amino-functionalized resin; Step 2: The amino-functionalized resin is placed in a second solvent for secondary swelling. After the secondary swelling is completed, N,N-dioctyl-2-chloroacetamide solution is slowly added dropwise to the system. An inert gas is introduced under stirring conditions to carry out a secondary heating reaction to obtain PS-TODGA-NH2 resin. Step 3: Add the PS-TODGA-NH2 resin to the fourth solvent, and add an acid-binding agent and dialkyl phosphite. Stir and swell three times. After the three swellings are completed, add an oxidant and perform three heating reactions to obtain the functionalized resin for recovering neodymium from rare earth ore leaching solution.

2. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 1, the ratio of the amount of chlorinated spheres to the amination reagent is 1g:(5-8)mL.

3. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 1, the reaction temperature during the first heating reaction is 110-150℃, and the reaction time is 15-25h.

4. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 2, the mass ratio of the amino-functionalized resin to the N,N-dioctyl-2-chloroacetamide solution is 1:(0.1-0.4), and the mass concentration of the N,N-dioctyl-2-chloroacetamide solution is 20%-60%.

5. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 2, during the second heating reaction, the reaction temperature is 25-60℃ and the reaction time is 3-8h.

6. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 3, the ratio of PS-TODGA-NH2 resin to dialkyl phosphite is 1g:(2.5-6)mL, and the dialkyl phosphite is at least one of dimethyl phosphite, diethyl phosphite, di-n-propyl phosphite, diisopropyl phosphite, di-n-butyl phosphite, diisobutyl phosphite, and di-tert-butyl phosphite.

7. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 3, the mass ratio of the PS-TODGA-NH2 resin to the oxidant is 1:(0.5-2).

8. The method for preparing a functionalized resin for recovering neodymium from rare earth ore leaching solution according to claim 1, characterized in that, In step 3, the reaction temperature during the three heating reactions is 40-60℃, and the reaction time is 12-24h.

9. A functionalized resin for recovering neodymium from rare earth ore leachate, characterized in that, The functionalized resin for recovering neodymium from rare earth ore leaching solution is prepared by any one of claims 1 to 8; the matrix of the functionalized resin is a polystyrene matrix, and the polystyrene matrix is ​​grafted with amide groups and phosphonate groups. The amide group is formed by the reaction of N,N-dioctyl-2-chloroacetamide with an amino group; The phosphonate group is formed by the reaction of a dialkyl phosphite with an amino group.

10. The application of the functionalized resin for recovering neodymium from rare earth ore leachate as described in claim 9 in the recovery of neodymium.

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