A method for preparing a dialkylphosphonic acid mixed extractant from olefin byproducts produced using P507 extractant, the obtained extractant, and its applications.

Abstract

This invention relates to a method for preparing a dialkylphosphonic acid mixed extractant from olefin byproducts produced using P507 extractant, the obtained extractant, and its applications. The dialkylphosphonic acid mixed extractant obtained by the method of this invention exhibits high saponification rate, large saturation capacity, minimal crystallization during saponification, minimal emulsification during extraction, low back-extraction acidity, and a high separation coefficient for adjacent rare earth ions, making it suitable for the extraction and separation of rare earth ions.

Description

Technical Field

[0001] This invention belongs to the fields of hydrometallurgy and organic synthesis, specifically relating to a method for preparing a dialkylphosphonic acid mixed extractant using olefin byproducts produced by P507 extractant, the obtained extractant, and the uses of the extractant. Background Technology

[0002] Numerous studies have shown that dialkylphosphonic acids containing two CP bonds exhibit excellent performance in rare earth separation, Ni / Co separation, and Ni / Mg separation, specifically characterized by high separation coefficients and ease of back-extraction. For example, the C272 extractant with the structure shown below is the only commercially available dialkylphosphonic acid containing two CP bonds. However, the C272 extractant also has the following problems in its use: (1) Saponification requires 40°C. o (1) If the concentration of C272 is above 40%, the extraction process is very easy to emulsify and the phase separation is very slow, resulting in low saturation capacity and insufficient extraction capacity. In practical applications, a large number of extraction stages are often required, the amount of extractant used is large, and the investment cost is high. In addition, during the extraction process, the extractant formed by C272 extractant and rare earth ions has high polarity and low lipophilicity, and is very easy to form phosphinate polymer precipitates, which leads to low extraction capacity, easy emulsification of the separation system, and even makes it difficult to clarify when the organic phase and aqueous phase are mixed. The viscosity of the organic phase increases, and in severe cases, it becomes gel-like, which reduces the extraction efficiency and limits the application of single extractant in the field of rare earth separation. The drawbacks of C272 extractant are closely related to its molecular structure: the P=O and P-OH groups in the C272 molecule are highly polar, and the P atom is directly connected to two electron-donating alkyl chains, leading to an increased electron cloud density on the P=O group; furthermore, the β-C branch of P in the C272 molecule is a methyl group, which has relatively low steric hindrance and therefore cannot effectively prevent water molecules from approaching the polar groups in its molecule. Therefore, C272 extractant easily forms water-in-oil emulsions during saponification and extraction, especially when the saponification rate is high, the emulsification is more severe, and higher operating temperatures are usually required to eliminate emulsification in order to suppress the degree of water-in-oil emulsion.

[0003] C272 extractant

[0004] The P229 extractant, as shown below, is also a dialkylphosphonic acid containing two CP bonds. The branched chain on the β-C of the P group in its molecule is ethyl, resulting in significant steric hindrance. Therefore, this extractant does not easily crystallize during saponification. Furthermore, the high steric hindrance effectively prevents water molecules from approaching the P=O polar group in its molecule, making emulsification difficult during the extraction process. However, the synthesis of this extractant using the free radical method requires 2-ethyl-1-hexene, but this raw material has not yet been industrially produced. Therefore, the P229 extractant has not yet achieved large-scale production.

[0005] P229 extractant

[0006] In non-ferrous metal smelting, cobalt and nickel often coexist. The P507 extractant, with the structure shown below, is effective for cobalt (Co). 2+ Its extraction capability is far superior to that for nickel (Ni). 2+ The P507 extractant exhibits high extraction efficiency. Under specific pH conditions, cobalt preferentially enters the organic phase, while nickel remains in the aqueous phase, achieving efficient separation. Therefore, P507 extractant is widely used in the treatment of cobalt-nickel alloys, waste catalyst recovery, and laterite nickel ore leaching solutions to produce high-purity cobalt and nickel salts. Rare earth elements have very similar chemical properties, making separation extremely difficult. The P507 extractant shows slight but crucial differences in its extraction ability for different rare earth ions; its extraction ability increases with increasing atomic number (decreasing ionic radius). Industrially, a cascade countercurrent extraction technique is typically used, where a feed solution containing mixed rare earth elements is countercurrently contacted with an organic phase containing P507 extractant in hundreds of extraction tanks to separate adjacent elements and produce a single high-purity rare earth product.

[0007] P507 extractant

[0008] Currently, the annual production of P507 extractant reaches 50,000 tons, and the chemical reactions involved in its production process are as follows:

[0009] ①. Synthesis of diisooctyl phosphite:

[0010] 3C8H 17 OH + PCl3 → (C8H 17 O)2P(O)H + C8H 17 Cl + 2HCl

[0011] ②. Synthesis of sodium diisooctyl phosphite:

[0012] (C8H 17 O)2P(O)H + C8H 17 ONa → (C8H 17 O)2P(O)Na + C8H 17 OH

[0013] ③. Synthesis of O,O-di(isooctyl)isooctylphosphonate (abbreviated as: intermediate ester):

[0014] (C8H 17 O)2P(O)Na + C8H 17 Cl → (C8H 17 O)2P(O)(C8H 17 ) + NaCl

[0015] ④. Synthesis of sodium salt of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester:

[0016] (C8H 17 O)2P(O)(C8H 17 ) + NaOH → (C8H 17 O)-P(O)ONa-(C8H 17 )+C8H 17 OH

[0017] ⑤. Synthesis of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (i.e., P507)

[0018] (C8H 17 O)-P(O)ONa-(C8H 17 ) + HCl → (C8H 17 O)-P(O)OH-(C8H 17 ) + NaCl

[0019] In step 3 of the reaction, a closed reactor was used, and the synthesis reactor was equipped with a safety valve. The reaction temperature was controlled at 190-220°C. o C. As the reaction proceeds, the pressure inside the reactor increases. When the pressure exceeds 0.22 MPa, it will automatically depressurize. The resulting tail gas is condensed and collected in a storage tank. It is a liquid at room temperature. P507 manufacturers typically treat this olefin byproduct as hazardous waste. Statistics show that this olefin byproduct accounts for 5% to 10% of P507 production, approximately 2500 to 5000 tons annually. Therefore, the high-value utilization of olefin byproducts in P507 extractant production and the further development of high-performance novel metal separation extractants for rare earth separation are of significant research value. Summary of the Invention

[0020] The problem the invention aims to solve

[0021] To address the technical problems existing in the high-value utilization of olefin by-products in the production of dialkylphosphonic acid extractants and P507 extractants in the prior art, this invention provides a method for preparing a dialkylphosphonic acid mixed extractant using olefin by-products in the production of P507 extractant, the obtained extractant, and the uses of the extractant. The dialkylphosphonic acid mixed extractant obtained by the method of this invention has a high saponification rate, a large saturation capacity, is not easily crystallized during the saponification process, is not easily emulsified during the extraction process, has low back-extraction acidity, and has a high separation coefficient for adjacent rare earth ions.

[0022] Solution for solving the problem

[0023] [1] A method for preparing a dialkylphosphonic acid mixed extractant using olefin byproducts produced by P507 extractant, comprising the following steps:

[0024] Step 1) Mix the olefin byproducts from the production of P507 extractant, sodium hypophosphite or hypophosphite, acid, and peroxide initiator to obtain a mixture;

[0025] Step 2) React the above mixture to obtain the reaction product;

[0026] Step 3) The reaction product is washed, acidified, and then dried to obtain a dialkylphosphonic acid mixed extractant;

[0027] In step 1), the peroxide initiator is di-tert-butyl peroxide.

[0028] The acid is selected from one or more of glacial acetic acid, propionic acid, and butyric acid.

[0029] [2] According to the method described in [1], the characteristic is that, in step 1),

[0030] The molar ratio of olefin byproducts, sodium hypophosphite or hypophosphite, acid and peroxide initiator in the production of the P507 extractant is (2.5-3.0):1:(0.1-1.0):(0.01-0.2).

[0031] [3] According to the method described in [1] or [2], the temperature of the reaction in step 2) is 120-150 °C and the reaction time is 24-48 h.

[0032] [4] The method according to [1] or [2] is characterized in that the dialkylphosphonic acid mixed extractant comprises the following components:

[0033] (A)

[0034] (B)

[0035] (C)

[0036] (D)

[0037] (E).

[0038] [5] A dialkylphosphonic acid mixed extractant, which is prepared according to any one of [1]-[4].

[0039] [6] The use of the dialkylphosphonic acid mixed extractant described in [5] for the extraction and separation of rare earth ions, the use comprising the following steps:

[0040] (1) The dialkylphosphonic acid mixed extractant described in [5] is mixed with a diluent to obtain the extractable organic phase;

[0041] (2) The extracted organic phase is subjected to a saponification reaction with an alkaline solution to obtain a saponified organic phase;

[0042] (3) The saponified organic phase is mixed with the pre-extraction feed solution and extracted to obtain the loaded organic phase and the raffinate aqueous phase;

[0043] (4) The loaded organic phase is washed with acid, and the washed loaded organic phase is back-extracted. The back-extracted blank organic phase is returned to step (1) for recycling.

[0044] [7] According to the use described in [6], the characteristic is that, in step (1), the volume percentage of the extractant in the extracted organic phase is 5% to 50%.

[0045] [8] According to the use described in [6] or [7], characterized in that, in step (2),

[0046] The alkaline solution is liquid alkali or ammonia water; and / or,

[0047] The concentration of the alkaline solution is 5-10 mol / L; and / or,

[0048] The saponification rate of the extracted organic phase is 10%~60%.

[0049] [9] According to the use described in [6] or [7], characterized in that, in step (3),

[0050] The pre-extraction feed solution is an aqueous solution containing rare earth ions; wherein the rare earth ions are selected from La. 3+ Ce 3+ Pr 3+ 、Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ 、Tb 3+ Dy 3+ Ho 3+ Y 3+ Er 3+ Tm 3+ Yb 3+ and Lu 3+ One or more of them; and / or,

[0051] The concentration of the aqueous solution containing rare earth ions is 0.01-1.0 mol / L; and / or,

[0052] The volume ratio of the saponified organic phase to the pre-extraction feed solution is organic phase / aqueous phase = 5:1 to 1:5; and / or,

[0053] The extraction process employs multi-stage countercurrent extraction.

[0054]

[10] According to the use described in [6] or [7], characterized in that, in step (4),

[0055] The volume ratio of the supported organic phase to the washing acid is organic phase / aqueous phase = 40:1 to 5:1; and / or,

[0056] The washing process employs multi-stage counter-current washing; and / or,

[0057] The acid used for washing is hydrochloric acid, and the concentration of the acid used for washing is 0.1~0.5 mol / L; and / or,

[0058] The acid used for back-extraction is hydrochloric acid, and the concentration of the acid used for back-extraction is 2~6 mol / L; and / or,

[0059] The volume ratio of the washed loaded organic phase to the acid used for back-extraction is organic phase / aqueous phase = 40:1~2:1; and / or,

[0060] The back-extraction employs multi-stage countercurrent back-extraction.

[0061] The effects of the invention

[0062] This invention utilizes the olefin byproducts from the production of P507 extractant to prepare a dialkylphosphonic acid mixed extractant. This fully utilizes the olefin byproducts, reducing waste emissions, and creatively transforms them into a high-performance, high-value-added dialkylphosphonic acid extractant, offering significant environmental and economic benefits. The resulting dialkylphosphonic acid mixed extractant exhibits advantages such as high saponification rate, large saturation capacity, resistance to crystallization during saponification, resistance to emulsification during extraction, and low back-extraction acidity. The dialkylphosphonic acid mixed extractant provided by this invention can be used for the extraction and separation of rare earth ions, achieving the purpose of rare earth separation and exhibiting a high separation coefficient for adjacent rare earth ions. Detailed Implementation

[0063] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0064] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0065] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0066] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0067] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0068] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0069] First, the inventors analyzed the composition of olefin byproducts in the production of P507 extractant. The typical composition of the olefin byproducts is shown in the table below:

[0070]

[0071] Analysis shows that the main component of the olefin byproduct is 2-ethyl-1-hexene (approximately 63%), with another significant component being 2-ethyl-2-hexene. These can be used as raw materials for synthesizing sterically hindered dialkylphosphonic acids. Stericly hindered dialkylphosphonic acid molecules are not prone to aggregation, and after saponification to form sodium salts, they do not easily agglomerate into soap salt crystals. When used as extractants, they allow for a high saponification rate and do not require heating. Furthermore, these extractants exhibit high steric hindrance near the polar groups P=O and P-OH, making it difficult for water molecules to approach the polar groups. Therefore, these extractants have excellent lipophilicity, are less likely to form water-in-oil emulsions, and thus have a high saturation capacity. Therefore, the olefin byproducts generated during the production of P507 extractant can be used to synthesize high-performance metal separation extractants, especially in the field of rare earth separation. This can comprehensively improve rare earth extraction capacity and separation efficiency, while reducing back-extraction acidity and achieving high-value utilization of waste.

[0072] This invention provides a method for preparing a dialkylphosphonic acid mixed extractant using olefin byproducts from the production of P507 extractant, comprising the following steps:

[0073] Step 1) Mix the olefin byproducts from the production of P507 extractant, sodium hypophosphite or hypophosphite, acid, and peroxide initiator to obtain a mixture;

[0074] Step 2) React the above mixture to obtain the reaction product;

[0075] Step 3) The reaction product is washed, acidified, and then dried to obtain a dialkylphosphonic acid mixed extractant;

[0076] In step 1), the peroxide initiator is selected from one or more of di-tert-butyl peroxide, tert-butyl peroxide, di-tert-pentyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane, tert-butyl maleate peroxide and tert-butyl peroxide, preferably di-tert-butyl peroxide.

[0077] The acid is selected from one or more of glacial acetic acid, propionic acid and butyric acid, with glacial acetic acid being preferred.

[0078] According to the method of the present invention, the peroxide initiator added in step 1) can be added in batches, for example, in two or more batches, such as three or four batches. More specifically, a portion of all the peroxide initiator to be added is added in step 1), and the remaining peroxide initiator is added in batches after the reaction begins in step 2). Preferably, the time interval between each batch is the same, and the interval can be 6-12 hours, for example, 7 hours, 8 hours, 9 hours, or 10 hours.

[0079] According to the method of the present invention, in step 1), the molar ratio of olefin by-product, sodium hypophosphite or hypophosphite, acid and peroxide initiator in the production of P507 extractant is (2.5-3.0):1:(0.1-1.0):(0.01-0.2).

[0080] According to the method of the present invention, in step 2), the reaction temperature is 120-150°C, for example, 125°C, 130°C, 135°C, 140°C, 145°C, etc.

[0081] According to the method of the present invention, the reaction time is 24-48 h, for example, 28 h, 30 h, 32 h, 34 h, 36 h, 38 h, 40 h, 42 h, 44 h, 46 h, etc.

[0082] According to the method of the present invention, in step 3), the reaction product is transferred to a separatory funnel, washed with deionized water and an alkaline solution, then acidified with an acidic solution to a pH of 2-3 in the aqueous phase, and finally washed with deionized water to a neutral pH in the aqueous phase. The washed organic phase is dried and distilled under reduced pressure to obtain a dialkylphosphonic acid mixed extractant. The alkaline solution can be a 1 mol / L NaOH solution. The acidic solution can be a 2 mol / L H₂SO₄ solution. The reduced pressure distillation temperature can be 80-100℃, and the time can be 0.5-2 h.

[0083] According to the method of the present invention, the dialkylphosphonic acid mixed extractant comprises the following components:

[0084] (A)

[0085] (B)

[0086] (C)

[0087] (D)

[0088] (E).

[0089] The present invention also provides a dialkylphosphonic acid mixed extractant, which is prepared according to the aforementioned method.

[0090] The present invention also provides an application of the aforementioned dialkylphosphonic acid mixed extractant for the extraction and separation of rare earth ions, the application comprising the following steps:

[0091] (1) The aforementioned dialkylphosphonic acid mixed extractant is mixed with a diluent to obtain the extractable organic phase;

[0092] (2) The extracted organic phase is subjected to a saponification reaction with an alkaline solution to obtain a saponified organic phase;

[0093] (3) The saponified organic phase is mixed with the pre-extraction feed solution and extracted to obtain the loaded organic phase and the raffinate aqueous phase;

[0094] (4) The loaded organic phase is washed with acid, and the washed loaded organic phase is back-extracted. The back-extracted blank organic phase is returned to step (1) for recycling.

[0095] According to the method of the present invention, in step (1), the dialkylphosphonic acid mixed extractant may also be replaced with a mixed extractant obtained by mixing the dialkylphosphonic acid mixed extractant with one or two of the C272 extractant and P507 extractant.

[0096] According to the method of the present invention, in step (1), the diluent is a conventional alkane inert solvent oil, such as one or more selected from 260# solvent oil, sulfonated kerosene and light white oil.

[0097] According to the method of the present invention, in step (1), the volume percentage of the extractant in the extracted organic phase is 5% to 50%, for example, it can be 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, etc.

[0098] According to the method of the present invention, in step (2), the alkaline solution is liquid alkali or ammonia water, for example, 15 wt% to 30 wt% ammonia water.

[0099] According to the method of the present invention, in step (2), the concentration of the alkaline solution is 5~10 mol / L, for example, it can be 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, etc.

[0100] According to the method of the present invention, in step (2), the saponification rate of the extracted organic phase is 10% to 60%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, etc.

[0101] According to the method of the present invention, in step (3), the pre-extraction feed solution is an aqueous solution containing rare earth ions; wherein, the rare earth ions are selected from La 3+ Ce 3+ Pr 3+ 、Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ 、Tb 3+ Dy 3+ Ho3+ Y 3+ Er 3+ Tm 3+ Yb 3+ and Lu 3+ One or more of them.

[0102] In this invention, the source and specific type of rare earth ions are not limited. For example, they can be rare earth ore leaching purification solution, rare earth waste leaching purification solution, or rare earth ion solution obtained by dissolving rare earth oxides in acid.

[0103] According to the method of the present invention, in step (3), the concentration of the aqueous solution containing rare earth ions is 0.01-1.0 mol / L, for example, it can be 0.015 mol / L, 0.02 mol / L, 0.05 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.5 mol / L, 0.8 mol / L, etc.

[0104] According to the method of the present invention, in step (3), the volume ratio of the saponified organic phase to the pre-extraction liquid is organic phase / water phase = 5:1 to 1:5, for example, it can be 1:0.3, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, etc.

[0105] According to the method of the present invention, in step (3), the extraction is performed using multi-stage countercurrent extraction.

[0106] According to the method of the present invention, in step (4), the volume ratio of the loaded organic phase to the washing acid is organic phase / water phase = 40:1 to 5:1, for example, it can be 6:1, 8:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, etc.

[0107] According to the method of the present invention, in step (4), the washing adopts multi-stage countercurrent washing.

[0108] According to the method of the present invention, in step (4), the acid used for washing is hydrochloric acid, and the concentration of the acid used for washing is 0.1 ~ 0.5 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, etc.

[0109] According to the method of the present invention, in step (4), the acid used for back-extraction is hydrochloric acid, and the concentration of the acid used for back-extraction is 2~6 mol / L, for example, 3 mol / L, 4 mol / L, 5 mol / L, etc.

[0110] According to the method of the present invention, in step (4), the volume ratio of the washed loaded organic phase to the acid used for back-extraction is organic phase / water phase = 40:1 to 2:1, for example, it can be 3:1, 4:1, 5:1, 8:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, etc.

[0111] According to the method of the present invention, in step (4), the back-extraction adopts multi-stage countercurrent back-extraction.

[0112] Example

[0113] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0114] The composition of the olefin byproducts produced using the P507 extractant in the embodiments of this invention is shown below:

[0115]

[0116] Example 1: Preparation of a dialkylphosphonic acid mixed extractant

[0117] Step 1) Place 35 g of olefin byproducts from the production of P507 extractant, 10.6 g of sodium hypophosphite, 10 g of glacial acetic acid and 0.7 g of di-tert-butyl peroxide into a 100 mL sealed reactor with a polytetrafluoroethylene liner to obtain a mixture.

[0118] Step 2) The above mixture was reacted at 135°C for 32 hours, with 0.35 g of di-tert-butyl peroxide added every 8 hours for a total of three times; after the reaction was completed, the reaction product was obtained.

[0119] Step 3) Transfer the reaction product to a separatory funnel, wash three times with deionized water (30 mL × 3), then wash three times with 10 mL of 1 mol / L NaOH solution, then acidify with 2 mol / L H2SO4 solution to a pH of 2.5, and finally wash with deionized water to a neutral pH. Mix the washed organic phase with anhydrous MgSO4 to remove water, and then distill under reduced pressure at 85°C for 1 h to obtain a dialkylphosphonic acid mixed extractant (21.6 g, yield 88.3%, product density 0.92 g / cm³). 3 ).

[0120] Comparative Example 1: C272 Extractant

[0121] C272 extractant was purchased from Solvay SA.

[0122] Comparative Example 2: P507 Extractant

[0123] P507 extractant was purchased from Jiangxi Fengxing Chemical Co., Ltd.

[0124] Nuclear magnetic resonance characterization

[0125] The NMR spectra of the samples were tested using a 600M NMR spectrometer (JNM-ECA600, NEC Corporation, Japan). The testing procedure was as follows: 5 mg of the sample to be tested was dissolved in 0.5 ml of CDCl3 and placed into a dedicated NMR tube. The NMR tube was inserted into the rotor of the NMR spectrometer, and the sample probe at the center of the magnet was placed in the center. Appropriate parameters were set, and the sample was tested. 1 H, 31 P, 13 C NMR spectrum.

[0126] The dialkylphosphonic acid mixed extractant prepared in Example 1 was characterized by NMR, and the data are as follows:

[0127] 31 P-NMR (CDCl3, 600 MHz): δ 58.23, 59.10, 60.05, 62.56, 64.65.

[0128] 1 H-NMR (CDCl3, 600 MHz): δ 12.15-12.23 (m), δ 1.20-2.23 (m), δ 0.88-0.92 (m).

[0129] 13 C-NMR (CDCl3, 600 MHz): δ 34.25-36.16, 29.25-30.68, 27.01-27.82, 21.3-24.5, 14.10-15.2, 10.1-11.5.

[0130] The carbon spectrum of the product shows many single peaks, distributed between 10 and 40 ppm, indicating that there are no esters or carboxylic acids in the product, because the characteristic chemical shifts of these two types of compounds in the C spectrum are between 160 and 180 ppm.

[0131] In the 1H NMR spectrum of the product, the chemical shift peak in the range of 12.15-12.23 ppm is attributed to the hydroxyl hydrogen atom of the dialkylphosphonic acid, and the other chemical shifts are all between 0.8-2.3 ppm, indicating that there are no alcohols or ethers in the product.

[0132] The phosphorus spectrum of the product showed five singlets, indicating the presence of five organophosphorus compounds. The chemical shifts were between 59.0 and 65.0 ppm, consistent with the chemical shift characteristics of phosphorus (P) in dialkylphosphonic acids. This also indicates the absence of dialkyl phosphates, monoalkyl alkyl phosphonates, and trialkylphosphine oxides, as these three organophosphonate esters typically have P chemical shifts around 1.0 ppm, 35 ppm, and 45 ppm, respectively. In dialkylphosphonic acid molecules, the smaller the steric hindrance of the α-C atom adjacent to the P atom, the smaller the P chemical shift value; conversely, the larger the steric hindrance of the α-C atom adjacent to the P atom, the larger the P chemical shift value. Based on the composition of the raw olefin, it can be inferred that the dialkylphosphonic acid mixed extractant includes the following components:

[0133] (A)

[0134] (B)

[0135] (C)

[0136] (D)

[0137] (E).

[0138] Application Example 1

[0139] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to a final volume to prepare a 0.02 mol / L single rare earth ion solution (pre-extraction feed). The rare earth ion is La. 3+ Ce 3+ Pr 3+ 、Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ 、Tb 3+ Dy 3+ Ho 3+ Y 3+ Er 3 + Tm 3+ Yb 3+ Lu 3+ .

[0140] (1) Dissolve the dialkylphosphonic acid mixed extractant in 260# kerosene to prepare an extractive organic phase with a volume percentage of 15%;

[0141] (2) 25 oAt temperature C, a certain amount of 10M NaOH is added to the extracted organic phase to make the saponification rate of the extracted organic phase 20%, thus obtaining the saponified organic phase; the saponified organic phase is a homogeneous system with no soap salt crystallization.

[0142] (3) The saponified organic phase is thoroughly mixed with a single rare earth ion solution (pre-extraction feed liquid), the volume ratio of the saponified organic phase to the pre-extraction feed liquid is organic phase / water phase = 1:1 (v / v), and the phases are separated by standing to obtain the loaded organic phase and the raffinate aqueous phase.

[0143] The pH of the raffinate aqueous phase was adjusted using a small amount of hydrochloric acid or NaOH to approximately 3.0. The rare earth ion content was measured in the pH-adjusted raffinate aqueous phase, and the distribution ratio D of rare earth ions in the organic and aqueous phases was calculated. The separation coefficient β between adjacent rare earth elements was also calculated. n+1 / D n The larger β is, the better the separation performance of adjacent rare earth ions, as shown in Table 1.

[0144] Application Comparative Example 1-1

[0145] Referring to Application Example 1, with other parameters the same, the dialkylphosphonic acid mixed extractant was replaced with C272 extractant. In step (2), a saponified organic phase was obtained. The saponified organic phase was a homogeneous system with no soap salt crystallization.

[0146] Application Comparative Example 1-2

[0147] Referring to Application Example 1, with other parameters the same, the dialkylphosphonic acid mixed extractant was replaced with P507 extractant. In step (2), a saponified organic phase was obtained. The saponified organic phase was a homogeneous system with no soap salt crystallization.

[0148] Table 1. Extraction separation coefficients of different extractants for adjacent rare earth ions

[0149]

[0150] As can be seen from Table 1, the dialkylphosphonic acid mixed extractant in Example 1 has a better separation effect on adjacent rare earth ions than the C272 extractant in Comparative Example 1-1 and the P507 extractant in Comparative Example 1-2.

[0151] Back-extraction performance experiment

[0152] The smaller the radius of rare earth ions, the stronger their binding ability with the extractant. Therefore, organic phases loaded with heavy rare earth elements are more difficult to back-extract.

[0153] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to a final volume to prepare a 0.015 mol / L single heavy rare earth ion solution (pre-extraction feed). The heavy rare earth ion is Er.3+ Tm 3+ Yb 3+ Lu 3+ .

[0154] The saponified organic phases from Application Example 1, Application Comparative Example 1-1, and Application Comparative Example 1-2 were thoroughly mixed with a single heavy rare earth ion solution (pre-extraction feed solution). The volume ratio of the saponified organic phase to the pre-extraction feed solution was 1:1 (v / v). The mixtures were allowed to stand and separate to obtain a loaded organic phase and a raffinate aqueous phase.

[0155] The supported organic phase was washed with hydrochloric acid at a concentration of 0.1 mol / L. The volume ratio of the supported organic phase to the hydrochloric acid was 10:1 (organic phase / aqueous phase). The washed supported organic phase was then back-extracted with hydrochloric acid, and the heavy rare earth ions in the supported organic phase were back-extracted to the aqueous phase. The blank organic phase after back-extraction was recycled. The acid concentration C(H2O) required for complete back-extraction was recorded. + The higher the value, the higher the acidity required for back-extraction of the extractant, i.e., the more difficult it is to back-extract. The results are shown in Table 2.

[0156] Table 2. Required back-extraction acidity for loading heavy rare earth ions with different extractants

[0157]

[0158] As can be seen from Table 2, the back-extraction performance of the dialkylphosphonic acid mixed extractant in Example 1 for heavy rare earth ions is comparable to that of the C272 extractant in Comparative Example 1-1, and is significantly better than that of the P507 extractant in Comparative Example 1-2.

[0159] Application Example 2

[0160] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to a final volume to prepare a 0.1 mol / L single rare earth ion solution (pre-extraction feed). The rare earth ion is La. 3+ Ce 3+ Pr 3+ 、Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ 、Tb 3+ Dy 3+ Ho 3+ Y 3+ Er 3+ Tm 3+ Yb 3+ Lu 3+ .

[0161] (1) Preparation of the extractable organic phase: Dissolve the dialkylphosphonic acid mixed extractant in 260# kerosene to prepare an extractable organic phase with a volume percentage of 25%;

[0162] (2) Saponification: 25 o At temperature C, a certain amount of 10M NaOH is added to the extracted organic phase to make the saponification rate of the extracted organic phase 30%, thus obtaining the saponified organic phase; the saponified organic phase is a homogeneous system with no soap salt crystallization.

[0163] (3) The saponified organic phase is thoroughly mixed with a single rare earth ion solution (pre-extraction feed liquid), the volume ratio of the saponified organic phase to the pre-extraction feed liquid is organic phase / water phase = 2:1 (v / v), and the phases are separated by standing to obtain the loaded organic phase and the raffinate aqueous phase.

[0164] The pH of the raffinate aqueous phase was adjusted using a small amount of hydrochloric acid or NaOH to approximately 3.0. The rare earth ion content was measured in the pH-adjusted raffinate aqueous phase, and the distribution ratio D of rare earth ions in the organic and aqueous phases was calculated. The separation coefficient β between adjacent rare earth elements was also calculated. n+1 / D n The results are shown in Table 3.

[0165] Application of Comparative Example 2-1

[0166] Referring to Application Example 2, with other parameters remaining the same, the dialkylphosphonic acid mixed extractant was replaced with C272 extractant. In step (2), a saponified organic phase was obtained. A small amount of soap salt crystals precipitated in the saponified organic phase, affecting subsequent extraction. These crystals were added to 45... o Keeping the temperature at C for a period of time will cause the soap salt crystals to dissolve.

[0167] Application Comparative Example 2-2

[0168] Referring to Application Example 2, with other parameters the same, the dialkylphosphonic acid mixed extractant was replaced with P507 extractant. In step (2), a saponified organic phase was obtained. The saponified organic phase was a homogeneous system with no soap salt crystallization.

[0169] Table 3 Extraction separation coefficients of different extractants for adjacent rare earth ions

[0170]

[0171] As can be seen from Table 3, the dialkylphosphonic acid mixed extractant in Example 2 has a better separation effect on adjacent rare earth ions than the C272 extractant in Comparative Example 2-1 and the P507 extractant in Comparative Example 2-2.

[0172] Back-extraction performance experiment

[0173] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to a final volume to prepare a 0.06 mol / L single heavy rare earth ion solution (pre-extraction feed). The heavy rare earth ion is Er. 3+ Tm 3+ Yb 3+ Lu 3+ .

[0174] The saponified organic phases from Application Example 2, Application Comparative Example 2-1, and Application Comparative Example 2-2 were thoroughly mixed with a single heavy rare earth ion solution (pre-extraction feed solution). The volume ratio of the saponified organic phase to the pre-extraction feed solution was 2:1 (v / v). The mixtures were allowed to stand and separate to obtain a loaded organic phase and a raffinate aqueous phase.

[0175] The supported organic phase was washed with hydrochloric acid at a concentration of 0.3 mol / L. The volume ratio of the supported organic phase to the hydrochloric acid was 15:1 (organic phase / aqueous phase). The washed supported organic phase was then back-extracted with hydrochloric acid, and the heavy rare earth ions in the supported organic phase were back-extracted to the aqueous phase. The blank organic phase after back-extraction was recycled. The acid concentration C(H2O) required for complete back-extraction was recorded. + The higher the value, the higher the acidity required for back-extraction of the extractant, i.e., the more difficult it is to back-extract. The results are shown in Table 4.

[0176] Table 4. Required back-extraction acidity for heavy rare earth elements loaded with different extractants

[0177]

[0178] As can be seen from Table 4, the back-extraction performance of the dialkylphosphonic acid mixed extractant in Example 2 for heavy rare earth ions is comparable to that of the C272 extractant in Comparative Example 2-1, and is significantly better than that of the P507 extractant in Comparative Example 2-2.

[0179] Application Example 3

[0180] (1) Preparation of the extractable organic phase: Dissolve the dialkylphosphonic acid mixed extractant in 260# kerosene to prepare an extractable organic phase with a volume percentage of 30%;

[0181] (2) Saponification: 25 o At temperature C, a certain amount of 10M NaOH is added to the extracted organic phase to make the saponification rate of the extracted organic phase 40%, thus obtaining the saponified organic phase; the saponified organic phase is a homogeneous system with no soap salt crystallization.

[0182] Application Comparative Example 3-1

[0183] Referring to Application Example 3, with other parameters remaining the same, the dialkylphosphonic acid mixed extractant was replaced with C272 extractant. In step (2), a saponified organic phase was obtained. Many soap salts crystallized and precipitated in the saponified organic phase, which seriously affected the subsequent extraction. It was added to 45 o When kept at a temperature of C for an extended period, the soap salt crystals dissolve.

[0184] Application Comparative Example 3-2

[0185] Referring to Application Example 3, with other parameters the same, the dialkylphosphonic acid mixed extractant was replaced with P507 extractant. In step (2), a saponified organic phase was obtained. The saponified organic phase was a homogeneous system with no soap salt crystallization.

[0186] Extraction and separation performance experiment

[0187] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to volume to prepare a 0.5 mol / L single rare earth ion solution (pre-extraction feed). The rare earth ion is La. 3+ Ce 3+ Pr 3+ 、Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ 、Tb 3+ Dy 3+ Ho 3+ Y 3+ Er 3 + Tm 3+ Yb 3+ Lu 3+ .

[0188] The saponified organic phases from Application Example 3, Application Comparative Example 3-1, and Application Comparative Example 3-2 were thoroughly mixed with a single rare earth ion solution (pre-extraction feed solution). The volume ratio of the saponified organic phase to the pre-extraction feed solution was 4:1 (v / v). The mixtures were allowed to stand and separate to obtain a loaded organic phase and a residual aqueous phase.

[0189] The pH of the raffinate aqueous phase was adjusted using a small amount of hydrochloric acid or NaOH to approximately 3.0. The rare earth ion content was measured in the pH-adjusted raffinate aqueous phase, and the distribution ratio D of rare earth ions in the organic and aqueous phases was calculated. The separation coefficient β between adjacent rare earth elements was also calculated. n+1 / D n The results are shown in Table 5.

[0190] Table 5 Extraction separation coefficients of different extractants for adjacent rare earth ions

[0191]

[0192] As can be seen from Table 5, the dialkylphosphonic acid mixed extractant in Example 3 has a better separation effect on adjacent rare earth ions than the C272 extractant in Comparative Example 3-1 and the P507 extractant in Comparative Example 3-2.

[0193] Back-extraction performance experiment

[0194] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to a final volume to prepare a 0.15 mol / L single heavy rare earth ion solution (pre-extraction feed). The heavy rare earth ion is Er. 3+ Tm 3+ Yb 3+ Lu 3+ .

[0195] The saponified organic phases from Application Example 3, Application Comparative Example 3-1, and Application Comparative Example 3-2 were thoroughly mixed with a single heavy rare earth ion solution (pre-extraction feed solution). The volume ratio of the saponified organic phase to the pre-extraction feed solution was 4:1 (v / v). The mixtures were allowed to stand and separate to obtain a loaded organic phase and a residual aqueous phase.

[0196] The supported organic phase was washed with hydrochloric acid at a concentration of 0.5 mol / L. The volume ratio of the supported organic phase to the hydrochloric acid was 20:1 (organic phase / aqueous phase). The washed supported organic phase was then back-extracted with hydrochloric acid, and the heavy rare earth ions in the supported organic phase were back-extracted to the aqueous phase. The blank organic phase after back-extraction was recycled. The acid concentration C(H2O) required for complete back-extraction was recorded. + The higher the value, the higher the acidity required for back-extraction of the extractant, i.e., the more difficult it is to back-extract. The results are shown in Table 6.

[0197] Table 6. Required back-extraction acidity for heavy rare earth elements loaded with different extractants

[0198]

[0199] As can be seen from Table 6, the back-extraction performance of the dialkylphosphonic acid mixed extractant in Example 3 for heavy rare earth ions is comparable to that of the C272 extractant in Comparative Example 3-1, and is significantly better than that of the P507 extractant in Comparative Example 3-2.

[0200] Application Example 4

[0201] (1) Preparation of the extractable organic phase: Dissolve the dialkylphosphonic acid mixed extractant in 260# kerosene to prepare an extractable organic phase with a volume percentage of 10%;

[0202] (2) Saponification: 25 oAt temperature C, a certain amount of 10M NaOH is added to the extracted organic phase to make the saponification rate of the extracted organic phase 20%, thus obtaining the saponified organic phase; the saponified organic phase is a homogeneous system with no soap salt crystallization.

[0203] Application Comparative Example 4-1

[0204] Referring to Application Example 4, with other parameters the same, the dialkylphosphonic acid mixed extractant was replaced with C272 extractant. In step (2), a saponified organic phase was obtained. The saponified organic phase was a homogeneous system with no soap salt crystallization.

[0205] Application of Comparative Example 4-2

[0206] Referring to Application Example 4, with other parameters the same, the dialkylphosphonic acid mixed extractant was replaced with P507 extractant. In step (2), a saponified organic phase was obtained. The saponified organic phase was a homogeneous system with no soap salt crystallization.

[0207] Saturation capacity experiment

[0208] Weigh out specific amounts of rare earth oxides, dissolve them in hydrochloric acid, and dilute to volume to prepare a 0.1 mol / L single heavy rare earth ion solution (pre-extraction feed). The heavy rare earth ion is Er. 3+ Tm 3+ Yb 3+ Lu 3+ .

[0209] The volume ratio of the saponified organic phase to the pre-extraction feed solution was 1:1 (v / v). The saponified organic phases from Application Example 4, Comparative Example 4-1, and Comparative Example 4-2 were repeatedly contacted with fresh pre-extraction feed solution. During extraction, the pH of the system was adjusted to approximately 3.0 until the organic phase began to emulsify. Then, a sufficient amount of 6 mol / L hydrochloric acid was used to back-extract the heavy rare earth ions from the organic phase to the aqueous phase. The concentration of heavy rare earth ions in the aqueous phase was tested, and the saturation capacity of each extractant was calculated. The results are shown in Table 7.

[0210] Table 7. Saturation capacity of different extractants for extracting heavy rare earth elements

[0211]

[0212] As can be seen from Table 7, the saturation capacity of the dialkylphosphonic acid mixed extractant in Application Example 4 for heavy rare earth ions is significantly higher than that of the C272 extractant in Comparative Example 4-1, and comparable to that of the P507 extractant in Comparative Example 4-2.

[0213] In summary, the dialkylphosphonic acid mixed extractant obtained by this invention has superior performance in rare earth ion extraction and separation, specifically in the following aspects:

[0214] (1) The average separation coefficient of dialkylphosphonic acid mixed extractant for adjacent rare earth elements is higher than that of P507 extractant and C272 extractant;

[0215] (2) At room temperature, the dialkylphosphonic acid mixed extractant can achieve a high saponification rate. Even if the saponification rate reaches 40%, no soap salt crystals will be produced. However, at room temperature, the C272 extractant will produce soap salt crystals if the saponification rate is higher than 20%. The higher the saponification rate, the more severe the soap salt crystals will be, which will clog the extraction system. It is necessary to heat it to 45°C. o C, soap salt crystals gradually dissolve, increasing the investment cost and operating energy consumption of the extraction system equipment;

[0216] (3) Under the same rare earth ion loading rate, the back-extraction acidity of the dialkylphosphonic acid mixed extractant is significantly lower than that of the P507 extractant. Therefore, the hydrochloric acid consumption in the back-extraction process is low, which greatly reduces the amount of NaOH required for subsequent pH adjustment to prepare rare earth salts. This reduces the acid and alkali consumption cost in the rare earth separation process and also reduces acid and alkali pollution.

[0217] (4) The saturation capacity of dialkylphosphonic acid mixed extractant for heavy rare earth ions is significantly higher than that of C272 extractant. Its advantages are high processing capacity, small running volume, small amount of extractant added at one time, and low investment cost.

[0218] In summary, the dialkylphosphonic acid mixed extractant synthesized using olefin byproducts from P507 extractant production as raw materials exhibits a slightly higher saturation capacity than the traditional rare earth separation extractant P507, superior separation performance, and significantly better back-extraction performance. Furthermore, its separation performance is slightly better than that of C272 extractant, while its saponification rate and saturation capacity are significantly superior. These advantages make the dialkylphosphonic acid mixed extractant a promising next-generation rare earth separation extractant, offering significant economic and environmental benefits.

Claims

1. A method for preparing a dialkylphosphonic acid mixed extractant using olefin byproducts from the production of P507 extractant, comprising the following steps: Step 1) Mix the olefin byproducts from the production of P507 extractant, sodium hypophosphite or hypophosphite, acid, and peroxide initiator to obtain a mixture; Step 2) React the above mixture to obtain the reaction product; Step 3) The reaction product is washed, acidified, and then dried to obtain a dialkylphosphonic acid mixed extractant; In step 1), The peroxide initiator is di-tert-butyl peroxide. The acid is selected from one or more of glacial acetic acid, propionic acid and butyric acid; The molar ratio of olefin byproducts, sodium hypophosphite or hypophosphite, acid, and peroxide initiator in the production of the P507 extractant is (2.5-3.0):1:(0.1-1.0):(0.01-0.2). The composition of the olefin byproducts produced in the production of the P507 extractant is as follows: In step 2), the reaction temperature is 120-150 °C; the reaction time is 24-48 h.

2. The use of a dialkylphosphonic acid mixed extractant obtained according to claim 1 for the extraction and separation of rare earth ions, the use comprising the following steps: (1) The dialkylphosphonic acid mixed extractant obtained according to claim 1 is mixed with a diluent to obtain the extractable organic phase; The volume percentage of the extractant in the organic phase being extracted is 5% to 50%. (2) The extracted organic phase is subjected to a saponification reaction with an alkaline solution to obtain a saponified organic phase; (3) The saponified organic phase is mixed with the pre-extraction feed solution and extracted to obtain the loaded organic phase and the raffinate aqueous phase; (4) The loaded organic phase is washed with acid, and the washed loaded organic phase is back-extracted. The back-extracted blank organic phase is returned to step (1) for recycling.

3. The use according to claim 2, characterized in that, In step (2), The alkaline solution is liquid alkali or ammonia water; and / or, The concentration of the alkaline solution is 5-10 mol / L; and / or, The saponification rate of the extracted organic phase is 10%~60%.

4. The use according to claim 2, characterized in that, In step (3), The pre-extraction feed solution is an aqueous solution containing rare earth ions; wherein the rare earth ions are selected from La. 3+ Ce 3+ Pr 3+ 、Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ 、Tb 3+ Dy 3+ Ho 3+ Y 3+ Er 3+ Tm 3+ Yb 3+ and Lu 3+ One or more of them; and / or, The concentration of the aqueous solution containing rare earth ions is 0.01-1.0 mol / L; and / or, The volume ratio of the saponified organic phase to the pre-extraction feed solution is organic phase / aqueous phase = 5:1 to 1:5; and / or, The extraction process employs multi-stage countercurrent extraction.

5. The use according to claim 2, characterized in that, In step (4), The volume ratio of the supported organic phase to the washing acid is organic phase / aqueous phase = 40:1 to 5:1; and / or, The washing process employs multi-stage counter-current washing. And / or, The acid used for washing is hydrochloric acid, and the concentration of the acid used for washing is 0.1~0.5 mol / L; and / or, The acid used for back-extraction is hydrochloric acid, and the concentration of the acid used for back-extraction is 2~6 mol / L; and / or, The volume ratio of the washed loaded organic phase to the acid used for back-extraction is organic phase / aqueous phase = 40:1~2:1; and / or, The back-extraction employs multi-stage countercurrent back-extraction.

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