Method for extracting and separating neodymium and gadolinium in neodymium-iron-boron waste or solution by using non-aqueous-phase organic solvent

Abstract

The invention provides a method for extracting and separating neodymium and gadolinium in neodymium-iron-boron waste or a solution by using a non-aqueous-phase organic solvent. Novel non-aqueous phase organic solvents diacetone alcohol, ethylene glycol and diethylene glycol are mixed with water to form a high-polarity (MP) organic phase, 260 # solvent oil is used as a diluent, P507 is used as an extraction agent to form a low-polarity (LP) organic phase, and the two phases are mixed to construct an efficient non-aqueous phase solvent extraction system. According to the extraction system, a polar organic solvent (such as diacetone alcohol, ethylene glycol and diethylene glycol) with low dielectric constant and low viscosity is used for replacing most of water to form a high-polarity organic phase, and an acid extraction agent P507 and 260 # solvent oil are used for forming a low-polarity organic phase to reduce acid and alkali loss and wastewater discharge; therefore, green and efficient separation of rare earth elements neodymium and gadolinium is realized. According to the system, the extraction efficiency of gadolinium can reach 98.99%, and the separation factor of gadolinium and neodymium reaches up to 656.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solvent extraction in the field of rare earth hydrometallurgy, and particularly relates to a method for separating neodymium and gadolinium in neodymium-iron-boron waste or solution by non-aqueous phase organic solvent extraction. BACKGROUND

[0002] Rare earths are widely used in optical, electrical, and magnetic materials due to their unique physical and chemical properties, and have become an indispensable strategic resource in the field of high-tech. Neodymium-iron-boron magnets, as a kind of rare earth permanent magnet material, are widely used in new energy, electronic information and other industries due to their high residual magnetic flux density, high coercivity, large magnetic energy product, and good stability. In the production process of neodymium-iron-boron magnets, about 25% of waste is generated due to process and equipment conditions, and the mass fraction of rare earth elements in the waste is about 33%. Generally, the chemical composition of such waste contains 10.7-30.73% of neodymium (Nd), 0.02-1.51% of gadolinium (Gd), and other high-value rare earth components. Therefore, recycling of Nd, Gd and other valuable rare earth resources is a key problem faced by the current rare earth permanent magnet industry, and also conforms to the current concept of resource recycling.

[0003] The separation of rare earth elements covers 15 lanthanide elements and chemically similar scandium and yttrium, which is extremely challenging due to the high similarity of the physical and chemical properties of adjacent elements. Solvent extraction (SX) is the most widely used method for industrial separation of rare earth elements, which is based on the difference in the distribution behavior of the rare earth elements to be separated between the aqueous and organic phases to achieve purification and enrichment. The organic phase of this process is usually composed of extractants and diluents, and modifiers are added as needed to adjust the extraction performance. In this extraction process, rare earth ions are highly hydrated in the aqueous phase to form hydrated rare earth ions, and the extractant forms a neutral or charged complex with the rare earth ions through coordination or ion exchange, causing it to transfer from the aqueous phase to the organic phase. Due to the similar strong hydration structure of all rare earth ions in the aqueous phase and the small difference in ionic radius, the separation factor (β) is small, and the separation efficiency is low, and usually requires multiple extractions (hundreds to thousands of levels) to achieve effective separation.

[0004] Based on the above reasons, the present application is proposed. SUMMARY

[0005] The present application aims to provide a non-aqueous organic solvent extraction system to improve the separation coefficient of neodymium and gadolinium, and apply it to separate and recover neodymium and gadolinium from neodymium iron boron waste or solution. The extraction system uses low dielectric constant and low viscosity polar organic solvents (such as diacetone alcohol, ethylene glycol, diethylene glycol) to replace most of the water to form a high-polarity organic phase, and uses an acidic extractant 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507) and solvent oil No. 260 to form a low-polarity organic phase to reduce acid-base loss and wastewater discharge, thereby realizing green and efficient separation of rare earth elements neodymium and gadolinium.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] In the first aspect, the present application provides a method for extracting and separating neodymium and gadolinium in neodymium iron boron waste by a non-aqueous organic solvent, comprising the following steps:

[0008] 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester is diluted by a diluent to obtain a low-polarity organic phase;

[0009] The polar organic solvent is dissolved in water to obtain a high-polarity organic phase;

[0010] After the neodymium iron boron waste is subjected to acid leaching, it is filtered to obtain a rare earth solution;

[0011] The rare earth solution is added to the high-polarity organic phase, and after adjusting the pH to be less than or equal to 6, a high-polarity organic phase containing rare earth ions is obtained;

[0012] The high-polarity organic phase containing rare earth ions is mixed with the low-polarity organic phase, oscillated, and after extraction equilibrium, centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate.

[0013] Preferably, it further comprises:

[0014] The gadolinium-rich organic phase is washed by an inorganic acid solution, and the gadolinium-rich organic phase after washing is stripped by an inorganic acid solution to obtain a gadolinium solution;

[0015] The neodymium in the neodymium-rich raffinate is extracted by 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester, and then stripped by an inorganic acid solution to obtain a neodymium solution.

[0016] In the second aspect, the present application further provides a method for extracting and separating neodymium and gadolinium in a solution by a non-aqueous organic solvent, comprising the following steps:

[0017] 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester is diluted by a diluent to obtain a low-polarity organic phase;

[0018] The polar organic solvent is dissolved in water to obtain a high-polarity organic phase;

[0019] A solution containing neodymium and gadolinium was added to the highly polar organic phase, and the pH was adjusted to ≤6 to obtain a highly polar organic phase containing rare earth ions.

[0020] The highly polar organic phase containing rare earth ions was mixed with the low polar organic phase, shaken, extracted to equilibrium, and then centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate.

[0021] The gadolinium-rich organic phase is washed with an inorganic acid solution, and then the washed gadolinium-rich organic phase is back-extracted with an inorganic acid solution to obtain a gadolinium solution.

[0022] Neodymium in the neodymium-rich raffinate was extracted using 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted using an inorganic acid solution to obtain a neodymium solution.

[0023] The method for non-aqueous organic solvent extraction and separation of neodymium and gadolinium from neodymium iron boron waste or solution of the present invention has the following advantages compared with the prior art:

[0024] 1. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction of the present invention uses non-aqueous solvent extraction (NASX) technology to efficiently separate rare earth elements from rare earth secondary resources. NASX replaces the traditional aqueous phase with polar molecular organic solvents (PMOSs) to form a dual organic phase system of "high polarity (MP) organic phase - low polarity (LP) organic phase," thereby improving separation performance. The NASX system improves the extraction efficiency of the extractant for rare earth elements, especially the β between light and medium-heavy rare earth elements, reduces the number of extraction stages, and significantly reduces acid and alkali emissions. Specifically, this extraction system uses low dielectric constant and low viscosity polar organic solvents (such as diacetone alcohol, ethylene glycol, and diethylene glycol) to replace most of the water to form a high polarity organic phase, and uses the acidic extractant 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) and No. 260 solvent oil to form a low polarity organic phase to reduce acid and alkali losses and wastewater emissions, thereby achieving green and efficient separation of rare earth elements neodymium and gadolinium.

[0025] 2. The non-aqueous organic solvent extraction method for separating neodymium and gadolinium from neodymium-iron-boron waste of the present invention innovatively uses diacetone alcohol (DAA) as a novel non-aqueous solvent, which is mixed with water to form a highly polar organic phase. 260# solvent oil is used as a diluent, and 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) is used as the extractant to form a low-polarity organic phase. The two phases are mixed to construct a highly efficient non-aqueous solvent extraction system (NASX). Using a non-aqueous solvent extraction system consisting of 0.25 mol / L P507 and 70 vol% DAA, the extraction efficiency of gadolinium reaches as high as 98.99%, and the separation factor β of gadolinium and neodymium is [not specified in the original text]. Gd / NdThe system achieves a high efficiency of 656, enabling efficient separation between Nd and Gd, far exceeding that of traditional solvent extraction systems. Simultaneously, this system is also effective for separating Nd+FeB waste (Nd...). 3+ 1285.55 mg / L, Gd 3+ (316.77 mg / L) exhibited excellent separation performance: at P 507 At a concentration of 0.02 mol / L, the extraction efficiency of gadolinium reached 98.13%, and the separation factor between gadolinium and neodymium reached 106. This invention, through the discovery of a novel non-aqueous solvent DAA, constructed a new NASX system, thereby achieving efficient separation of gadolinium and neodymium, providing an innovative solution for the recovery of valuable rare earth elements from neodymium-iron-boron waste. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The effects of different types of polar organic solvents on the extraction efficiency of neodymium and gadolinium extraction in Examples 1-3 and Comparative Example 1 of this invention;

[0028] Figure 2 The effects of different types of polar organic solvents on the separation coefficients of neodymium and gadolinium extraction in Examples 1-3 and Comparative Example 1 of this invention;

[0029] Figure 3 This illustrates the effect of the volume ratio of DAA in a highly polar organic phase on the extraction efficiency of neodymium and gadolinium in Example 4 of the present invention.

[0030] Figure 4 This illustrates the effect of different phase ratios on the extraction efficiency of neodymium and gadolinium in Example 5 of the present invention.

[0031] Figure 5 This illustrates the effect of different pH values ​​in a highly polar organic phase on the extraction efficiency of neodymium and gadolinium in Example 6 of the present invention.

[0032] Figure 6 This illustrates the effect of different extraction times on the extraction efficiency of neodymium and gadolinium in Example 7 of the present invention.

[0033] Figure 7 This illustrates the effect of different temperatures on the extraction efficiency of neodymium and gadolinium in Example 8 of the present invention.

[0034] Figure 8The effect of the concentration of P507 in the low-polarity organic phase on the extraction efficiency of gadolinium and neodymium in Example 9 of this invention;

[0035] Figure 9 This invention illustrates the effect of different HCl concentrations on the washing effect of neodymium in gadolinium-rich organic phases and the back-extraction of gadolinium in Example 10.

[0036] Figure 10 This invention relates to the effect of different HNO3 concentrations on the washing effect of neodymium in gadolinium-rich organic phases and the effect of gadolinium back-extraction in Example 10.

[0037] Figure 11 This invention relates to the effect of different H2SO4 concentrations on the washing effect of neodymium in gadolinium-rich organic phases and the back-extraction of gadolinium in Example 10 of the present invention.

[0038] Figure 12 The results show the extraction efficiency of neodymium and gadolinium in simulated NdFeB waste under different P507 concentrations in Example 11 of this invention.

[0039] Figure 13 The results of the separation coefficients of neodymium and gadolinium in simulated neodymium iron boron waste extracted and separated under different P507 concentrations in Example 11 of the present invention;

[0040] Figure 14 This is a process flow diagram of the method for separating neodymium and gadolinium from solution using non-aqueous organic solvent extraction in Example 11. Detailed Implementation

[0041] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0042] The order in which the embodiments are described below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that 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., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0043] This invention provides a method for separating neodymium and gadolinium from neodymium iron boron waste using non-aqueous organic solvent extraction, comprising the following steps:

[0044] S1. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester (P507, CAS No. 14802-03-0, molecular formula C...) 16 H 35 O3P was diluted with a diluent (i.e., 2-ethylhexyl phosphate mono-2-ethylhexyl ester was added to the diluent) to obtain a low-polarity organic phase;

[0045] S2. Dissolve a polar organic solvent in water to obtain a highly polar organic phase;

[0046] S3. After acid leaching, the NdFeB waste is filtered to obtain a rare earth solution;

[0047] S4. Add the rare earth solution to the highly polar organic phase, adjust the pH to ≤6, and obtain a highly polar organic phase containing rare earth ions.

[0048] S5. Mix the high-polarity organic phase containing rare earth ions with the low-polarity organic phase, shake, extract to equilibrium, and centrifuge to obtain the gadolinium-rich organic phase and the neodymium-rich raffinate.

[0049] The present invention relates to a method for separating neodymium and gadolinium from neodymium iron boron waste using non-aqueous solvent extraction (NASX) technology. This method efficiently separates rare earth elements from rare earth secondary resources. NASX replaces the traditional aqueous phase with polar molecular organic solvents (PMOSs) to form a dual organic phase system of "high polarity (MP) organic phase - low polarity (LP) organic phase," thereby improving separation performance. The NASX system improves the extraction efficiency of the extractant for rare earth elements, especially the β between light and medium-heavy rare earth elements, reduces the number of extraction stages, and significantly reduces acid and alkali emissions. Specifically, this extraction system uses low dielectric constant and low viscosity polar organic solvents (such as diacetone alcohol, ethylene glycol, and diethylene glycol) to replace most of the water to form a high polarity organic phase, and uses the acidic extractant 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) and No. 260 solvent oil to form a low polarity organic phase to reduce acid and alkali losses and wastewater emissions, thereby achieving green and efficient separation of rare earth elements neodymium and gadolinium.

[0050] The acidic extractant P507 selected in this invention exhibits excellent chemical stability, a large saturation capacity and good phase separation effect when extracting heavy rare earth elements, mild back-extraction conditions, and recyclability, perfectly meeting the core requirements of industrial production for "reliability, low cost, and easy scalability." The application of the NASX system significantly reduces the extraction process and the discharge of acid and alkaline wastewater, achieving green extraction and separation of rare earth elements and minimizing environmental damage.

[0051] In some embodiments, it also includes:

[0052] S6. The gadolinium-rich organic phase is washed with an inorganic acid solution, and then the washed gadolinium-rich organic phase is back-extracted with an inorganic acid solution to obtain a gadolinium solution.

[0053] S7. Neodymium in the neodymium-rich raffinate is extracted using 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted using an inorganic acid solution to obtain a neodymium solution.

[0054] Specifically, in step S5, gadolinium is almost completely extracted, resulting in a gadolinium-rich organic phase, while most of the neodymium remains in the raffinate, which is a neodymium-rich raffinate. The gadolinium-rich organic phase also contains a small amount of co-extracted neodymium, which can be washed clean with an inorganic acid solution (such as 0.01 mol / L hydrochloric acid solution). The washed gadolinium-rich organic phase can then be back-extracted with an inorganic acid solution (such as 1 mol / L hydrochloric acid solution) to obtain a gadolinium-rich back-extract, which is a high-purity gadolinium solution. Regarding the neodymium-rich raffinate, the neodymium in it is extracted again using the acidic extractant 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted with 1 mol / L hydrochloric acid to obtain a neodymium-rich back-extract, which is a high-purity neodymium solution. This completes the separation of neodymium and gadolinium.

[0055] In some embodiments, the polar organic solvent includes diacetone alcohol (DAA, CAS No. 123-42-2, molecular formula C6H). 12 O2), ethylene glycol (EG, molecular formula C2H6O2), diethylene glycol (DEG, chemical formula C4H6O2), and diethylene glycol (DEG, chemical formula C4H6O2). 10 At least one of O3), preferably, the polar organic solvent is diacetone alcohol, diacetone alcohol (DAA), which has low toxicity, extremely low viscosity, low volatility, stable chemical properties, low price and easy availability, and is suitable for large-scale industrial applications. DAA can regulate the solvation of rare earth ions in the extraction system, so that the acidic extractant P507 can achieve efficient extraction and separation of rare earth neodymium and gadolinium at low concentrations.

[0056] The diluent is No. 260 solvent oil, i.e., No. 260 solvent oil.

[0057] In some embodiments, a rare earth solution is added to a highly polar organic phase, and after adjusting the pH to ≤6, a highly polar organic phase containing rare earth ions is obtained. Specifically, the higher the pH value, the better the extraction and separation effect, but it should not be too high. Too high a pH value can easily lead to the hydrolysis and precipitation of rare earth ions. It is preferable to have a pH value ≤6, for example, a pH value of 5~6. Specifically, an acid such as HCl is used to adjust the pH.

[0058] In some embodiments, a highly polar organic phase containing rare earth ions is mixed with a low polar organic phase, and the mixture is shaken at 200-300 r / min for 10-60 min at 20-45°C. After extraction equilibrium, the mixture is centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate. Preferably, the mixture is shaken at 300 r / min for 40 min at 25°C. After extraction equilibrium, the mixture is centrifuged at 2500 r / min for 15 min to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate.

[0059] In some embodiments, the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.05~0.7 mol / L; preferably, the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 0.25 mol / L.

[0060] The volume fraction of the polar organic solvent in the highly polar organic phase is 10-90%, preferably 70%.

[0061] The volume ratio of the high polarity organic phase containing rare earth ions to the low polarity organic phase is (1~5):(1~5), preferably 1:1.

[0062] In some embodiments, an inorganic acid solution and a gadolinium-rich organic phase are mixed at a volume ratio of (1~2):(1~2), and the mixture is shaken at 200~300 r / min for 30~40 min at 20~30°C to wash the gadolinium-rich organic phase; then, the washed gadolinium-rich organic phase is mixed with an inorganic acid solution at a volume ratio of (1~2):(1~2), and the mixture is shaken at 200~300 r / min for 30~40 min at 20~30°C to back-extract the gadolinium-rich organic phase to obtain a gadolinium solution;

[0063] 2-Ethylhexyl phosphate mono-2-ethylhexyl ester was mixed with the neodymium-rich raffinate at a volume ratio of (1~2):(1~2), and the mixture was shaken at 200~300 r / min for 30~40 min at 20~30℃ to extract neodymium from the raffinate, yielding a neodymium-rich extract phase. The neodymium-rich extract phase was then mixed with an inorganic acid solution at a volume ratio of (1~2):(1~2), and the mixture was shaken at 200~300 r / min for 30~40 min at 20~30℃ to back-extract the neodymium-rich extract phase, yielding a neodymium solution.

[0064] The inorganic acid solution is any one of hydrochloric acid solution, nitric acid solution, or sulfuric acid solution;

[0065] The concentration of the inorganic acid solution is 0.01~3 mol / L.

[0066] In some embodiments, in the step of mixing the inorganic acid solution with the gadolinium-rich organic phase at a volume ratio of (1~2):(1~2), the inorganic acid solution is a hydrochloric acid solution with a concentration of 0.01 mol / L;

[0067] In the step of mixing the washed gadolinium-rich organic phase with the inorganic acid solution at a volume ratio of (1~2):(1~2), the inorganic acid solution is a hydrochloric acid solution with a concentration of 1 mol / L.

[0068] In the step of mixing 2-ethylhexyl phosphate mono-2-ethylhexyl ester with the neodymium-rich extract residue at a volume ratio of (1~2):(1~2), the 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 2-ethylhexyl phosphate mono-2-ethylhexyl ester diluted with No. 260 solvent oil.

[0069] The concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester after dilution is 0.05~0.7 mol / L;

[0070] In the step of mixing the neodymium-rich extract phase with the inorganic acid solution at a volume ratio of (1~2):(1~2), the inorganic acid solution is a hydrochloric acid solution with a concentration of 1 mol / L.

[0071] In some embodiments, neodymium iron boron waste is subjected to acid leaching to obtain a rare earth solution; the specific steps are as follows:

[0072] Neodymium iron boron waste was added to 1 mol / L hydrochloric acid to dissolve it, and after filtration to remove impurities, a rare earth solution was obtained.

[0073] This invention innovatively employs diacetone alcohol (DAA) as a novel non-aqueous solvent, mixed with water to form a highly polar organic phase. 260# solvent oil is used as a diluent, and 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) is used as the extractant to form a low-polarity organic phase. The two phases are mixed to construct a highly efficient non-aqueous solvent extraction system (NASX). Using a non-aqueous solvent extraction system consisting of 0.25 mol / L P507 and 70 vol% DAA, the extraction efficiency of gadolinium reaches as high as 98.99%, and the separation factor β between gadolinium and neodymium is also high. Gd / Nd The system achieves a high efficiency of 656, enabling efficient separation between Nd and Gd, far exceeding that of traditional solvent extraction systems. Simultaneously, this system is also effective for separating Nd+FeB waste (Nd...). 3+ 1285.55 mg / L, Gd 3+ (316.77 mg / L) exhibited excellent separation performance: at P 507 At a concentration of 0.02 mol / L, the extraction efficiency of gadolinium reached 98.13%, and the separation factor between gadolinium and neodymium reached 106. This invention, through the discovery of a novel non-aqueous solvent DAA, constructed a new NASX system, thereby achieving efficient separation of gadolinium and neodymium, providing an innovative solution for the recovery of valuable rare earth elements from neodymium-iron-boron waste.

[0074] Based on the same inventive concept, the present invention also provides a method for separating neodymium and gadolinium from solution by non-aqueous organic solvent extraction, comprising the following steps:

[0075] S1. Dilute 2-ethylhexyl phosphate mono-2-ethylhexyl ester with a diluent to obtain a low-polarity organic phase;

[0076] S2. Dissolve a polar organic solvent in water to obtain a highly polar organic phase;

[0077] S3. Prepare a solution containing neodymium and gadolinium;

[0078] S4. Add the solution containing neodymium and gadolinium to the highly polar organic phase, and adjust the pH to ≤6 to obtain a highly polar organic phase containing rare earth ions;

[0079] S5. Mix the high polarity organic phase containing rare earth ions with the low polarity organic phase, shake, extract to equilibrium, and centrifuge to obtain the gadolinium-rich organic phase and the neodymium-rich extract residue.

[0080] S6. Wash the gadolinium-rich organic phase with an inorganic acid solution, and then back-extract the washed gadolinium-rich organic phase with an inorganic acid solution to obtain a gadolinium solution (this step is the same as step S6 above).

[0081] S7. The neodymium in the neodymium-rich extract is extracted using 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted using an inorganic acid solution to obtain a neodymium solution (this step is the same as step S7 above).

[0082] The methods for extracting and separating neodymium and gadolinium from solutions using non-aqueous organic solvents and for extracting and separating neodymium and gadolinium from neodymium-iron-boron waste using non-aqueous organic solvents are similar in procedure, except that in step S4, the rare earth solution is replaced with a solution containing neodymium and gadolinium; all other process parameters are the same. For example, the polar organic solvent includes at least one of diacetone alcohol, ethylene glycol, and diethylene glycol; preferably diacetone alcohol; the diluent is No. 260 solvent oil.

[0083] In some embodiments, a highly polar organic phase containing rare earth ions is mixed with a low polar organic phase, and the mixture is shaken at 200-300 r / min for 10-60 min at 20-45°C. After extraction equilibrium, the mixture is centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate. Preferably, the mixture is shaken at 300 r / min for 40 min at 25°C. After extraction equilibrium, the mixture is centrifuged at 2500 r / min for 15 min to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate.

[0084] In some embodiments, the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.01~0.7 mol / L; preferably, the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 0.25 mol / L. The volume fraction of polar organic solvent in the high-polarity organic phase is 10~90%, preferably 70%; the volume ratio of the high-polarity organic phase containing rare earth ions to the low-polarity organic phase is (1~5):(1~5), preferably 1:1.

[0085] The present invention will be further described in detail below through implementation examples. To further understand the present invention, preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention and not for limiting the scope of the present invention's patent claims.

[0086] In the process of this invention, after the extraction and back-extraction operations, the rare earth concentrations in the raffinate and back-extraction solution are determined by ICP-OES.

[0087] In the following examples and comparative examples, the formulas for calculating the rare earth partition ratio (D), extraction efficiency (%E), separation coefficient (β) between rare earth ions, and back-extraction efficiency (%Strip) of each rare earth ion are as follows:

[0088]

[0089]

[0090]

[0091]

[0092] Among them, C0 and C MP These represent the initial and equilibrium concentrations of rare earth ions in the highly polar organic phase, respectively. Specifically, for the rare earth ion gadolinium (Gd), C0 represents the concentration of gadolinium (Gd) in the highly polar organic phase containing rare earth ions in step S4 of the following example. MP This indicates the concentration of gadolinium (Gd) ions in the neodymium-rich extract residue in step S5 of the following examples; for neodymium (Nd) ions, C0 represents the concentration of neodymium (Nd) in the highly polar organic phase containing rare earth ions in step S4 of the following examples. MP This indicates the concentration of neodymium (Nd) ions in the neodymium-rich extract residue in step S5 of the following embodiments;

[0093] V MP V represents the volume of the highly polar organic phase containing rare earth ions in step S4 of the following embodiments. LP This indicates the volume of the low-polarity organic phase in step S1 of the following embodiments;

[0094] D A and D B These represent the distribution ratios of rare earth ions A (Gd) and B (Nd), respectively.

[0095] C s It refers to the concentration of rare earth ions in the back-extraction solution. Specifically, for the rare earth ion gadolinium (Gd), C s In step S6 of the following embodiment, the gadolinium-rich organic phase is washed with an inorganic acid solution to remove a small amount of co-extracted neodymium, and then the washed gadolinium-rich organic phase is back-extracted with an inorganic acid solution to obtain a (high-purity) gadolinium solution, wherein C s That is, the concentration of gadolinium (Gd) in a (high-purity) gadolinium solution; for the rare earth ion neodymium (Nd), C s In step S7 of the following embodiment, neodymium in the neodymium-rich raffinate is extracted using 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted using an inorganic acid solution to obtain a (high-purity) neodymium solution, wherein C s This is the concentration of neodymium (Nd) in a (high-purity) neodymium solution.

[0096] In the following examples, solvent oil No. 260 was purchased from Zhengzhou Hecheng New Material Technology Co., Ltd.

[0097] Example 1

[0098] This embodiment provides a method for separating neodymium and gadolinium from solution using a non-aqueous organic solvent extraction, including the following steps:

[0099] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0100] S2. Mix 7 mL of diacetone alcohol (DAA) with 3 mL of water to prepare a highly polar organic phase with 70 vol% polar organic solvent;

[0101] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0102] S4. Mix the high polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. Shake in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain gadolinium-rich organic phase and neodymium-rich extract residue.

[0103] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0104] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0105] Example 2

[0106] This embodiment provides a method for extracting and separating neodymium and gadolinium from a solution using a non-aqueous organic solvent. The method is the same as in Example 1, except that in step S2, 7 mL of diacetone alcohol (DAA) is replaced with 7 mL of ethylene glycol (EG). All other process parameters are the same as in Example 1.

[0107] Example 3

[0108] This embodiment provides a method for extracting and separating neodymium and gadolinium from a solution using a non-aqueous organic solvent. The method is the same as in Embodiment 1, except that in step S2, 7 mL of diacetone alcohol (DAA) is replaced with 7 mL of diethylene glycol (DEG). All other process parameters are the same as in Embodiment 1.

[0109] Comparative Example 1

[0110] This comparative example provides a method for extracting and separating neodymium and gadolinium from a solution in pure water, similar to Example 1, except that in step S2, the mixture of 7 mL diacetone alcohol (DAA) and 3 mL water is replaced with 10 mL of water. All other process parameters are the same as in Example 1.

[0111] In Examples 1-3 and Comparative Example 1, the effects of different types of polar organic solvents on the extraction of neodymium and gadolinium are as follows: Figures 1-2 As shown; Figures 1-2 In the middle, the horizontal axis H2O represents Comparative Example 1, DAA represents Example 1, EG represents Example 2, and DEG represents Example 3.

[0112] from Figures 1-2 As can be seen, compared with extraction from pure water, the addition of polar organic solvents can significantly improve the extraction efficiency of rare earth elements. Specifically, the non-aqueous phase system composed of DAA can increase the extraction efficiency of gadolinium from 76.86% to 98.99%, with a separation coefficient of 656 for gadolinium and neodymium. Considering both extraction efficiency and separation coefficient, DAA is the optimal polar organic solvent. Therefore, DAA is chosen as the polar organic solvent for constructing the optimal non-aqueous solvent extraction system for separating neodymium and gadolinium.

[0113] Example 4

[0114] This embodiment investigates the effect of the volume ratio of DAA in a highly polar organic phase on the extraction and separation of neodymium and gadolinium. Specifically, this embodiment provides a method for the extraction and separation of neodymium and gadolinium from solution using a non-aqueous organic solvent, comprising the following steps:

[0115] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0116] S2. Mix water and DAA in different proportions to prepare 10 mL of high polar organic phases containing 0 to 90 vol% DAA (the specific DAA concentrations are 0 vol%, 10 vol%, 20 vol%, 30 vol%, 40 vol%, 50 vol%, 60 vol%, 70 vol%, 80 vol%, 90 vol%, with 0 vol% being pure water).

[0117] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0118] S4. Mix the high polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. Shake in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain gadolinium-rich organic phase and neodymium-rich extract residue.

[0119] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0120] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0121] The effect of the volume ratio of DAA in a highly polar organic phase on the extraction and separation of neodymium and gadolinium is as follows: Figure 3As shown, calculations revealed that the extraction efficiency of neodymium and gadolinium continuously increased with the increase of the volume ratio of DAA in the highly polar organic phase. The extraction efficiency of gadolinium reached its maximum (98.89%) at a volume ratio of 70 vol%, at which point the separation coefficient between neodymium and gadolinium also reached its maximum (572). Subsequently, as the proportion of DAA continued to increase, the viscosity of the system gradually increased, leading to a slower mass transfer rate during extraction and a decrease in both extraction efficiency and separation ratio. Therefore, the optimal volume ratio of DAA in the highly polar organic phase is 70 vol%.

[0122] Example 5

[0123] This embodiment studies non-aqueous solvent extraction systems at different phase ratios (V). LP / V MP The following describes the effect of non-aqueous organic solvent extraction on the separation of neodymium and gadolinium. Specifically, this embodiment provides a method for separating neodymium and gadolinium from solution using non-aqueous organic solvent extraction, including the following steps:

[0124] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0125] S2. Mix 7 mL of diacetone alcohol (DAA) with 3 mL of water to prepare a highly polar organic phase with 70 vol% polar organic solvent;

[0126] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0127] S4. The high polarity organic phase containing rare earth ions in S3 and the low polarity organic phase in S1 are mixed at volume ratios of 5:1, 3:1, 1:1, 1:3, and 1:5, respectively. The mixture is shaken in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, the mixture is centrifuged at 2500 r / min for 15 min and then transferred to a 60 mL separatory funnel to stand and separate into layers to obtain a gadolinium-rich organic phase and a neodymium-rich extract.

[0128] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0129] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0130] Non-aqueous solvent extraction systems at different phases (V LP / V MP The effect of the volume ratio of highly polar organic phase containing rare earth ions to low polar organic phase on the extraction and separation of neodymium and gadolinium is as follows: Figure 4 As shown, the system exhibits a maximum separation coefficient of 607 at a ratio of 1:1, with a gadolinium extraction efficiency of 98.88% and a neodymium extraction efficiency of only 12.84%. This is because as the ratio increases, the extractant content in the NASX system also increases, leading to a gradual increase in the extraction efficiencies of gadolinium and neodymium, which in turn results in a decrease in the separation coefficient and thus a poorer separation effect. Conversely, a lower ratio results in a lower extractant content in the system, leading to fewer extraction complexes formed between rare earth ions and extractant molecules, resulting in poor extraction performance. Therefore, in this non-aqueous solvent extraction system, a ratio (V1:1) is crucial. LP / V MP The ratio was chosen as 1:1.

[0131] Example 6

[0132] This embodiment investigates the effect of a non-aqueous solvent extraction system on the extraction and separation of neodymium and gadolinium at different pH values ​​in a highly polar organic phase. Specifically, this embodiment provides a method for the extraction and separation of neodymium and gadolinium from solution using a non-aqueous organic solvent, comprising the following steps:

[0133] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0134] S2. Weigh 1.79345 g of neodymium chloride hexahydrate and 1.8585 g of gadolinium chloride hexahydrate and add them to 25 mL of water to obtain a rare earth solution;

[0135] Then, take 1 mL of rare earth solution and add 7 mL of DAA and 2 mL of water to form a highly polar organic phase containing a mixed rare earth solution of 0.02 mol / L neodymium and 0.02 mol / L gadolinium (where the volume fraction of DAA is 70%). Adjust the pH (adjust the pH to 4.52, 4.65, 4.82, 5.04, and 5.18 respectively), which is a highly polar organic phase containing rare earth ions.

[0136] S3. The highly polar organic phase containing rare earth ions in S2 and the low polar organic phase in S1 are mixed at a volume ratio of 1:1. The mixture is shaken in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, the mixture is centrifuged at 2500 r / min for 15 min and then transferred to a 60 mL separatory funnel to stand and separate into layers to obtain a gadolinium-rich organic phase and a neodymium-rich extract.

[0137] S4. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S3 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0138] S5. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0139] The effect of non-aqueous solvent extraction systems on the extraction and separation of neodymium and gadolinium at different pH values ​​in highly polar organic phases is as follows: Figure 5 As shown: Calculations show that the extraction efficiency of neodymium and gadolinium continuously increases with the increase of the pH value of the highly polar organic phase, reaching its maximum (633) at pH 5.18. This follows the cation exchange theory of extractant P507, where for every 1 mol of rare earth ions extracted, 3 mol of H+ will be exchanged. +Since the rare earth ions are released into a highly polar organic phase, the pH value of the highly polar organic phase must be strictly controlled. While ensuring that the rare earth ions do not undergo hydrolysis and precipitation, it is best to maintain a relatively high pH range. This will ensure good extraction and separation of neodymium and gadolinium. When the pH is below 6, the higher the pH value, the better. Taking all factors into consideration, a pH of 5.5 was chosen in this case.

[0140] Example 7

[0141] This embodiment investigates the effect of non-aqueous solvent extraction systems at different extraction times on the extraction and separation of neodymium and gadolinium. Specifically, this embodiment provides a method for the extraction and separation of neodymium and gadolinium from solution using non-aqueous organic solvents, comprising the following steps:

[0142] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0143] S2. Mix 7 mL of diacetone alcohol (DAA) with 3 mL of water to prepare a highly polar organic phase with 70 vol% polar organic solvent;

[0144] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0145] S4. Mix the high polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. Shake in a constant temperature water bath shaker at 25℃ and 300 r / min for 10~60 min (the specific shaking times are 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min). After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain the gadolinium-rich organic phase and the neodymium-rich extract residue.

[0146] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0147] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0148] The effect of non-aqueous solvent extraction system on the extraction and separation of neodymium and gadolinium at different extraction times is as follows: Figure 6 As shown, the extraction efficiency of neodymium and gadolinium increases with increasing oscillation time. The extraction efficiency of gadolinium reaches its maximum (98.99%) at an extraction time of 40 min, and remains essentially unchanged with further increases in extraction time. Therefore, to ensure sufficient extraction, 40 min is selected as the optimal extraction time.

[0149] Example 8

[0150] This embodiment studies the effect of non-aqueous solvent extraction systems at different temperatures on the extraction and separation of neodymium and gadolinium. Specifically, this embodiment provides a method for the extraction and separation of neodymium and gadolinium from solution using non-aqueous organic solvents, including the following steps:

[0151] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0152] S2. Mix 7 mL of diacetone alcohol (DAA) with 3 mL of water to prepare a highly polar organic phase with 70 vol% polar organic solvent;

[0153] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0154] S4. Mix the highly polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. In a constant temperature water bath shaker, shake at 20~45℃ (specific control temperatures are 20℃, 25℃, 30℃, 35℃, 40℃, and 45℃) and 300 r / min for 40 min. After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain a gadolinium-rich organic phase and a neodymium-rich extract.

[0155] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0156] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0157] The effect of non-aqueous solvent extraction systems on the extraction and separation of neodymium and gadolinium at different temperatures, as follows: Figure 7 As shown, calculations show that the extraction efficiencies of gadolinium at different temperatures are 97.94%, 99.02%, 91.70%, 88.44%, 87.45%, and 83.22%, respectively. The extraction efficiency of gadolinium is highest at an extraction temperature of 25 ºC, and the separation coefficient between gadolinium and neodymium is the largest (638). After that, the extraction efficiency of gadolinium gradually decreases with increasing temperature. Therefore, 25 ºC is chosen for the extraction reaction, which eliminates the need for additional heating and effectively reduces energy consumption.

[0158] Example 9

[0159] This embodiment investigates the effect of the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) in a low-polarity organic phase on the extraction and separation of neodymium and gadolinium. Specifically, this embodiment provides a method for the extraction and separation of neodymium and gadolinium from solution using a non-aqueous organic solvent, comprising the following steps:

[0160] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0~0.7 mol / L (specifically 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, and 0.7 mol / L).

[0161] S2. Mix 7 mL of diacetone alcohol (DAA) with 3 mL of water to prepare a highly polar organic phase with 70 vol% polar organic solvent;

[0162] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0163] S4. Mix the high polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. Shake in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain gadolinium-rich organic phase and neodymium-rich extract residue.

[0164] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0165] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0166] The effect of P507 concentration in the low-polarity organic phase on the extraction and separation of gadolinium and neodymium is as follows: Figure 8 As shown: Gadolinium extraction efficiency increases with P 507 The extraction efficiency of gadolinium increased with increasing concentration. At a P507 concentration of 0.25 mol / L, the extraction efficiency of gadolinium reached 99.22%, while that of neodymium was 17.26%, and the separation coefficients of gadolinium and neodymium reached their maximum (617). As the P concentration continued to increase... 507 At a concentration of 0.25 mol / L, the extraction efficiency of gadolinium remains essentially unchanged, while the extraction efficiency of neodymium continuously increases, thus the separation coefficients of gadolinium and neodymium continuously decrease. Therefore, the optimal P507 concentration for separating neodymium and gadolinium is 0.25 mol / L.

[0167] Example 10

[0168] This embodiment studies the washing effect of different inorganic acid concentrations on neodymium in a gadolinium-rich organic phase and the back-extraction effect on gadolinium. Specifically, this embodiment provides a method for separating neodymium and gadolinium from a solution using a non-aqueous organic solvent, including the following steps:

[0169] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L;

[0170] S2. Mix 7 mL of diacetone alcohol (DAA) with 3 mL of water to prepare a highly polar organic phase with 70 vol% polar organic solvent;

[0171] S3. Weigh 0.71738 g of neodymium chloride hexahydrate and 0.7434 g of gadolinium chloride hexahydrate respectively and add them to the highly polar organic phase in S2 to prepare a mixed rare earth solution containing 0.02 mol / L neodymium and 0.02 mol / L gadolinium. Adjust the pH to 5.5 to obtain the highly polar organic phase containing rare earth ions.

[0172] S4. Mix the high polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. Shake in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain gadolinium-rich organic phase and neodymium-rich extract residue.

[0173] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 0.01~3 mol / L (specifically 0.01 mol / L, 0.05 mol / L, 0.5 mol / L, 1 mol / L, 3 mol / L) hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0174] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 0.01~3 mol / L (specifically 0.01 mol / L, 0.05 mol / L, 0.5 mol / L, 1 mol / L, and 3 mol / L) hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0175] Following the same method described above, replace the 0.01–3 mol / L hydrochloric acid solution used in the back-extraction steps S5–S6 with a 0.01–3 mol / L HNO3 solution (specifically, concentrations of 0.01 mol / L, 0.05 mol / L, 0.5 mol / L, 1 mol / L, and 3 mol / L, respectively). The concentration of the HNO3 solution remains the same during the back-extraction steps S5–S6. During washing, the HNO3 concentration is kept constant at 0.01 mol / L.

[0176] Following the same method described above, replace the 0.01–3 mol / L hydrochloric acid solution used during back-extraction in steps S5–S6 with a 0.01–3 mol / L H2SO4 solution (specifically, concentrations of 0.01 mol / L, 0.05 mol / L, 0.5 mol / L, 1 mol / L, and 3 mol / L, respectively). The concentration of the H2SO4 solution remains the same during back-extraction in steps S5–S6. During washing, the H2SO4 concentration is kept constant at 0.01 mol / L.

[0177] The effects of different inorganic acid concentrations on the washing effect of neodymium and the back-extraction effect of gadolinium in gadolinium-rich organic phases, such as Figures 9-11As shown: Calculations show that in this embodiment, approximately 21.78% of neodymium was extracted into the organic phase. HCl, HNO3, and H2SO4 can all effectively wash out neodymium from the gadolinium-rich organic phase and back-extract gadolinium. HCl preferentially back-extracts neodymium from the supported organic phase; therefore, we chose HCl to wash the gadolinium-rich organic phase. A 0.01 mol / L HCl solution can quantitatively wash out 62.42% of the neodymium from the gadolinium-rich organic phase. Simultaneously, HCl was chosen for back-extraction of the gadolinium-rich organic phase. The back-extraction efficiency reached 97.04% at a 1 mol / L HCl concentration. Although the back-extraction efficiency reached 99.01% at a 3 mol / L HCl concentration, to avoid excessive acid usage and environmental damage, a 1 mol / L HCl solution was used for back-extraction of gadolinium, thus obtaining a high-purity gadolinium chloride solution. Therefore, the preferred inorganic acid for washing neodymium is 0.01 mol / L HCl, and the preferred inorganic acid for back-extracting gadolinium is 1 mol / L HCl.

[0178] Example 11

[0179] This embodiment studies the results of extracting and separating neodymium and gadolinium from simulated neodymium-iron-boron waste using a non-aqueous solvent extraction system at different P507 concentrations; specifically, this embodiment provides a method for extracting and separating neodymium and gadolinium from solution using a non-aqueous organic solvent, including the following steps:

[0180] S1. Add 2-ethylhexyl phosphate mono-2-ethylhexyl ester to solvent oil No. 260 to obtain a low-polarity organic phase; the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.01~0.4 mol / L (specifically 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, and 0.4 mol / L).

[0181] S3. Place 7.665g of neodymium iron boron waste powder in a 500ml beaker, add 1mol / L hydrochloric acid to completely dissolve it, filter to remove impurities, and make up to 500ml to obtain a rare earth solution containing 1285.55mg / L neodymium and 316.77mg / L gadolinium.

[0182] Take 1 mL of rare earth solution, add 7 mL of DAA and 2 mL of water to it, and adjust the pH to 5.5. This will give you a highly polar organic phase containing rare earth ions (where the volume fraction of DAA is 70%).

[0183] S4. Mix the high polar organic phase containing rare earth ions in S3 with the low polar organic phase in S1 at a volume ratio of 1:1. Shake in a constant temperature water bath shaker at 25℃ and 300 r / min for 40 min. After extraction equilibrium, centrifuge at 2500 r / min for 15 min and transfer to a 60 mL separatory funnel to stand and separate into layers to obtain gadolinium-rich organic phase and neodymium-rich extract residue.

[0184] S5. Mix 0.01 mol / L hydrochloric acid solution with the gadolinium-rich organic phase in S4 at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to wash the gadolinium-rich organic phase; then mix the washed gadolinium-rich organic phase with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and shake at 300 r / min for 30 min at 25 °C to back-extract the gadolinium-rich organic phase to obtain a high-purity gadolinium solution;

[0185] S6. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester diluted to 0.25 mol / L with solvent oil No. 260 is mixed with the neodymium-rich raffinate from S4 at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to extract neodymium from the raffinate, obtaining a neodymium-rich extract phase. The neodymium-rich extract phase is then mixed with 1 mol / L hydrochloric acid solution at a volume ratio of 1:1. The mixture is shaken at 300 r / min for 30 min at 25 °C to back-extract the neodymium-rich extract phase, obtaining a high-purity neodymium solution.

[0186] The results of the extraction and separation of neodymium and gadolinium in simulated NdFeB waste using a non-aqueous solvent extraction system are as follows: Figures 12-13 As shown, the extraction efficiency of both neodymium and gadolinium increases with the increase of P507 concentration. When the P507 concentration is 0.02 mol / L, the extraction efficiency of gadolinium reaches 98.13%, while the extraction efficiency of neodymium is only 33.19%, and the separation coefficient of neodymium and gadolinium reaches the maximum (106).

[0187] Figure 14 This is a process flow diagram of the method for separating neodymium and gadolinium from solution using non-aqueous organic solvent extraction in Example 11.

[0188] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0189] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for separating neodymium and gadolinium from neodymium-iron-boron waste using non-aqueous organic solvent extraction, characterized in that, Includes the following steps: 2-Ethylhexyl phosphate mono-2-ethylhexyl ester was diluted with a diluent to obtain a low-polarity organic phase; A highly polar organic phase is obtained by dissolving a polar organic solvent in water. After acid leaching, NdFeB waste is filtered to obtain a rare earth solution; A rare earth solution was added to the highly polar organic phase, and the pH was adjusted to ≤6 to obtain a highly polar organic phase containing rare earth ions. The highly polar organic phase containing rare earth ions was mixed with the low polar organic phase, shaken, extracted to equilibrium, and then centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate.

2. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 1, characterized in that, Also includes: The gadolinium-rich organic phase is washed with an inorganic acid solution, and then the washed gadolinium-rich organic phase is back-extracted with an inorganic acid solution to obtain a gadolinium solution. Neodymium in the neodymium-rich raffinate was extracted using 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted using an inorganic acid solution to obtain a neodymium solution.

3. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 1, characterized in that, The polar organic solvent includes at least one of diacetone alcohol, ethylene glycol, and diethylene glycol. And / or, the diluent is No. 260 solvent oil.

4. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 3, characterized in that, The high-polarity organic phase containing rare earth ions is mixed with the low-polarity organic phase, and the mixture is shaken at 20-45°C and 200-300 r / min for 10-60 min. After extraction equilibrium is reached, the mixture is centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich extract. The concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.05~0.7 mol / L; The volume fraction of the polar organic solvent in the highly polar organic phase is 10-90%. The volume ratio of the high polarity organic phase containing rare earth ions to the low polarity organic phase is (1~5):(1~5).

5. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 4, characterized in that, The polar organic solvent is diacetone alcohol; The volume fraction of the polar organic solvent in the highly polar organic phase is 70%. The concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.25 mol / L; The volume ratio of the high-polarity organic phase containing rare earth ions to the low-polarity organic phase is 1:

1. The highly polar organic phase containing rare earth ions was mixed with the low polar organic phase, and the mixture was shaken at 300 r / min for 40 min at 25 °C. After extraction equilibrium was reached, the mixture was centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate.

6. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 2, characterized in that, The inorganic acid solution is mixed with the gadolinium-rich organic phase at a volume ratio of (1~2):(1~2), and the mixture is shaken at 200~300 r / min for 30~40 min at 20~30℃ to wash the gadolinium-rich organic phase. The washed gadolinium-rich organic phase is then mixed with an inorganic acid solution at a volume ratio of (1~2):(1~2), and the mixture is shaken at 200~300 r / min for 30~40 min at 20~30℃ to back-extract the gadolinium-rich organic phase and obtain a gadolinium solution. 2-Ethylhexyl phosphate mono-2-ethylhexyl ester was mixed with the neodymium-rich raffinate at a volume ratio of (1~2):(1~2), and the mixture was shaken at 200~300 r / min for 30~40 min at 20~30℃ to extract neodymium from the raffinate, yielding a neodymium-rich extract phase. The neodymium-rich extract phase was then mixed with an inorganic acid solution at a volume ratio of (1~2):(1~2), and the mixture was shaken at 200~300 r / min for 30~40 min at 20~30℃ to back-extract the neodymium-rich extract phase, yielding a neodymium solution. The inorganic acid solution is any one of hydrochloric acid solution, nitric acid solution, and sulfuric acid solution; The concentration of the inorganic acid solution is 0.01~3 mol / L.

7. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 6, characterized in that, In the step of mixing the inorganic acid solution with the gadolinium-rich organic phase at a volume ratio of (1~2):(1~2), the inorganic acid solution is a hydrochloric acid solution with a concentration of 0.01 mol / L. In the step of mixing the washed gadolinium-rich organic phase with the inorganic acid solution at a volume ratio of (1~2):(1~2), the inorganic acid solution is a hydrochloric acid solution with a concentration of 1 mol / L. In the step of mixing 2-ethylhexyl phosphate mono-2-ethylhexyl ester with the neodymium-rich extract at a volume ratio of (1~2):(1~2), the 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 2-ethylhexyl phosphate mono-2-ethylhexyl ester diluted with No. 260 solvent oil, and the concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester after dilution is 0.05~0.7 mol / L; In the step of mixing the neodymium-rich extract phase with the inorganic acid solution at a volume ratio of (1~2):(1~2), the inorganic acid solution is a hydrochloric acid solution with a concentration of 1 mol / L.

8. The method for separating neodymium and gadolinium from neodymium iron boron waste by non-aqueous organic solvent extraction as described in claim 1, characterized in that, After acid leaching, neodymium iron boron waste is filtered to obtain a rare earth solution, specifically including the following steps: Neodymium iron boron waste was added to hydrochloric acid to dissolve it, and then filtered to obtain a rare earth solution.

9. A method for separating neodymium and gadolinium from solution using a non-aqueous organic solvent extraction process, characterized in that, Includes the following steps: 2-Ethylhexyl phosphate mono-2-ethylhexyl ester was diluted with a diluent to obtain a low-polarity organic phase; A highly polar organic phase is obtained by dissolving a polar organic solvent in water. A solution containing neodymium and gadolinium was added to the highly polar organic phase, and the pH was adjusted to ≤6 to obtain a highly polar organic phase containing rare earth ions. The highly polar organic phase containing rare earth ions was mixed with the low polar organic phase, shaken, extracted to equilibrium, and then centrifuged to obtain a gadolinium-rich organic phase and a neodymium-rich raffinate. The gadolinium-rich organic phase is washed with an inorganic acid solution, and then the washed gadolinium-rich organic phase is back-extracted with an inorganic acid solution to obtain a gadolinium solution. Neodymium in the neodymium-rich raffinate was extracted using 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and then back-extracted using an inorganic acid solution to obtain a neodymium solution.

10. The method for extracting and separating neodymium and gadolinium from solution using a non-aqueous organic solvent as described in claim 9, characterized in that, The polar organic solvent includes at least one of diacetone alcohol, ethylene glycol, and diethylene glycol. And / or, the diluent is No. 260 solvent oil; And / or, the high polarity organic phase containing rare earth ions is mixed with the low polarity organic phase, and the mixture is shaken at 20~45℃ and 200~300 r / min for 10~60 min. After extraction equilibrium, the mixture is centrifuged to obtain the gadolinium-rich organic phase and the neodymium-rich extract residue. The concentration of 2-ethylhexyl phosphate mono-2-ethylhexyl ester in the low-polarity organic phase is 0.05~0.7 mol / L; The volume fraction of the polar organic solvent in the highly polar organic phase is 10-90%. The volume ratio of the high polarity organic phase containing rare earth ions to the low polarity organic phase is (1~5):(1~5). And / or, the inorganic acid solution is any one of hydrochloric acid solution, nitric acid solution, and sulfuric acid solution; The concentration of the inorganic acid solution is 0.01~3 mol / L.

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