Method for comprehensive recovery of rare earth industrial waste residues

Abstract

The method for comprehensively recovering rare earth industrial waste residues provided by the application uses XM-SN extractant, and can effectively separate thorium, iron, aluminum, rare earth, calcium and magnesium in stages. The rare earth radioactive waste residue recovery process is simple, continuous and can be automatically produced, has good separation effect, a thorium and rare earth separation coefficient greater than 10000, an aluminum and rare earth separation coefficient greater than 300, can efficiently enrich rare earth elements, has high recovery rates of various elements, high purity of various products, low production cost, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to the field of rare earth element recovery, and specifically to a method for the comprehensive recovery of rare earth industrial waste. Background Technology

[0002] Rare earth elements possess unique physicochemical properties and are widely used in important fields such as machinery and electronics, petrochemicals, metallurgy, new energy, and aerospace, making them extremely important strategic resources for my country. my country boasts abundant rare earth reserves and a complete range of rare earth minerals, and its production has ranked first in the world for decades. Currently, the extraction and smelting processes of rare earth generate a large amount of waste residue, such as rare earth impurity removal residue, acid dissolution residue, and neutralization residue. These rare earth waste residues still contain high levels of rare earth, iron, and aluminum resources, possessing certain recycling value. Furthermore, some rare earth waste residues contain the radioactive element thorium, which is difficult to dispose of safely. Therefore, the comprehensive recycling of rare earth industrial waste residues is of great significance. Hydrometallurgical processes are one of the technical routes for the comprehensive recycling of valuable elements from rare earth industrial waste residues. However, the elemental composition of the leachate from rare earth industrial waste residues is complex, and achieving short-process, clean, and efficient separation of each element component is one of the challenges in the comprehensive recycling of radioactive waste residues from the rare earth industry. Summary of the Invention

[0003] To address the problems of existing technologies, this invention provides a method for the comprehensive recycling of rare earth industrial waste, comprising the following steps:

[0004] (1) First stage extraction: XM-SN extractant is added to the leachate of rare earth industrial waste to extract a first organic phase loaded with thorium and / or iron and a first raffinate; the first organic phase is back-extracted to obtain a thorium and / or iron back-extract.

[0005] (2) Second stage extraction: XM-SN extractant is added to the first raffinate to extract the second organic phase loaded with aluminum and the second raffinate; the second organic phase is back-extracted to obtain the aluminum back-extract.

[0006] (3) Third stage extraction: XM-SN extractant is added to the second raffinate to extract the third organic phase loaded with lanthanide rare earth and the third raffinate; the third organic phase is back-extracted to obtain the lanthanide rare earth back-extracting solution.

[0007] (4) Fourth stage extraction: XM-SN extractant is added to the third raffinate to extract the fourth organic phase loaded with yttrium and the fourth raffinate; the fourth organic phase is back-extracted to obtain the yttrium back-extract;

[0008] According to an embodiment of the present invention, the XM-SN extractant comprises a main component and an activator; the molar ratio of the main component to the activator is 0.1-10; for example, 1:(0.5-6), and exemplary ratios are 1:1, 1:2, 1:3, 1:4, 1:5, and 1:9.

[0009] According to embodiments of the present invention, the main components include, but are not limited to, one, two, or more of long-chain fatty acids and their derivatives, ibuprofen, gemfibrozil, and other drug derivatives; preferably, the main components are one or more of decanoic acid, lauric acid, oleic acid, linoleic acid, trans oleic acid, γ-linolenic acid, eicosenoic acid, erucic acid, myristic acid, palmitic acid, stearic acid, arachidic acid, ibuprofen, gemfibrozil, syringic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, and capryloyl salicylic acid;

[0010] According to an embodiment of the present invention, the activator is one or more of the following: long-chain alcohols, long-chain phenols, sulfonic acids, diketones, pyridine carboxylates, hydroxyquinoline, aldoximes, ketoximes, long-chain fatty acids, amides, ibuprofen, gemfibrozil, lecithin, long-chain alkyl phosphoric acids, long-chain alkyl hypophosphite, primary amines, tertiary amines, secondary amines, hydrophobic quaternary phosphine salts, hydrophobic quaternary ammonium salts, tributyl phosphate, and submolten salts. Preferably, the activator is one or more of the following: octanol, decanol, undecylol, dodecanol, tetradecylol, 1,2-decanediol, 1,2-lauryl diol, menthol, thymol, phenol, long-chain fatty acids, tributyl phosphate, N-(2-hydroxyethyl)dodecylamide, N,N-diethyldodecylamine, 1,3-diphenyl-1,3-propanedione, diisooctylamine, and N1923.

[0011] According to an embodiment of the present invention, the XM-SN extractant may further include an antiemulsifier, such as one or more of TBP, nonylphenol, isooctanol, n-octanol, n-decanol, oleyl alcohol, No. 2 oil, menthol, N-(2-hydroxyethyl)dodecylamide, laurocapram, etc.

[0012] According to an embodiment of the present invention, the demulsifier accounts for 10-50% of the volume fraction of the main components and activators, for example, 20%, 30%, or 40%.

[0013] According to an embodiment of the present invention, the XM-SN extractant is a combination of oleic acid, decanol and tributyl phosphate or a combination of gemfibrozil and diisooctylamine.

[0014] According to an embodiment of the present invention, the leachate from the rare earth industrial waste is a leachate obtained by leaching with one or more of hydrochloric acid, nitric acid, and sulfuric acid;

[0015] According to an embodiment of the present invention, the pH of the leachate is 1-3.5, preferably 3.0.

[0016] According to an embodiment of the present invention, the volume ratio of the XM-SN extractant to the rare earth industrial waste leachate is 0.1-10.

[0017] According to an embodiment of the present invention, the radioactive waste residue from rare earth mines is one or more of the following: impurity removal residue, acid dissolution residue, neutralization residue, and other residues containing thorium, rare earth elements, iron, aluminum, calcium, and magnesium.

[0018] According to an embodiment of the present invention, the components in the leachate of rare earth industrial waste include, but are not limited to, at least one of thorium, iron, aluminum, rare earth, calcium, magnesium and / or rare earth elements;

[0019] According to an embodiment of the present invention, the extraction can be countercurrent cascade extraction.

[0020] According to an embodiment of the present invention, in step (1), the first organic phase loaded with thorium and / or iron is back-extracted using one or more inorganic or organic acids such as hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride to obtain the thorium and / or iron back-extract and the first regenerated XM-SN extractant; preferably, the first regenerated XM-SN extractant can be used for the second stage extraction; preferably, the concentration of the inorganic or organic acid is 1-6 mol / L, for example 1 mol / L;

[0021] According to an embodiment of the present invention, in step (1), the pH of the first raffinate can be adjusted to 3.5-4.0 using one or more of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate to remove the remaining small amount of thorium and / or iron before being used for the second stage extraction.

[0022] According to an embodiment of the present invention, in step (2), an alkaline compound is used to adjust the pH value of the equilibrium extraction system online during the second stage extraction. The alkaline compound may be selected from at least one of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate. Preferably, the amount of the alkaline compound used is 2 to 4 times the molar amount of aluminum. Preferably, the pH value is in the range of 3.0 to 3.75, for example 3.0, 3.2, and 3.5.

[0023] According to an embodiment of the present invention, in step (2), the extracted organic phase can be washed with an inorganic acid or an organic acid to obtain the second organic phase during the second stage extraction; the inorganic acid or organic acid can be selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride; preferably, the concentration of the inorganic acid or organic acid is 0.01-0.2 mol / L, for example 0.1 mol / L;

[0024] According to an embodiment of the present invention, in step (2), the second organic phase loaded with aluminum is back-extracted using one or more inorganic or organic acids such as hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride to obtain the aluminum back-extract and the second-regenerated XM-SN extractant; preferably, the concentration of the inorganic or organic acid is 0.01-1 mol / L, for example, 0.1 mol / L; preferably, the second-regenerated XM-SN extractant can be used for the third-stage extraction;

[0025] According to an embodiment of the present invention, the aluminum back-extraction solution may be selected from one or more of sodium fluoride, hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, aluminum fluoride, and sodium fluoroaluminate to remove trace amounts of rare earth elements.

[0026] According to an embodiment of the present invention, in step (3), the pH value of the equilibrium extraction system is adjusted online using an alkaline compound in the third stage of extraction. The alkaline compound may be selected from at least one of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate. Preferably, the amount of the alkaline compound is 2 to 4 times the molar amount of the rare earth element, for example, 3.2 times. Preferably, the pH value is in the range of 4.0 to 6.5, for example, 5.0, 5.5, and 6.0.

[0027] According to an embodiment of the present invention, in step (3), the third stage of extraction may use an inorganic acid or an organic acid to wash the extracted organic phase to obtain the third organic phase; the inorganic acid or organic acid may be selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride; preferably, the concentration of the inorganic acid or organic acid is 0.0001-0.2 mol / L, for example 0.001 mol / L;

[0028] According to an embodiment of the present invention, in step (3), the third organic phase loaded with lanthanide rare earth can be back-extracted using one or more inorganic or organic acids such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride to obtain the lanthanide rare earth back-extraction solution and the third regenerated extractant; preferably, the concentration of the inorganic or organic acid is 0.5-8 mol / L, for example, 6 mol / L; preferably, the third regenerated XM-SN extractant can be used for the fourth stage extraction;

[0029] According to an embodiment of the present invention, in step (4), the pH value of the equilibrium extraction system is adjusted online using an alkaline compound in the fourth stage of extraction. The alkaline compound may be selected from at least one of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate. Preferably, the pH value is in the range of 3-4, for example 3.3.

[0030] According to an embodiment of the present invention, in step (4), the fourth stage of extraction may use an inorganic acid or an organic acid to wash the extracted organic phase to obtain the fourth organic phase; the inorganic acid or organic acid may be selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride.

[0031] According to an embodiment of the present invention, in step (4), the fourth organic phase loaded with yttrium is back-extracted using one or more of the following inorganic or organic acids: hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, betaine hydrochloride, etc., to obtain the yttrium back-extract and the fourth regenerated XM-SN extractant.

[0032] According to an embodiment of the present invention, in step (4), the fourth raffinate is used to adjust the pH value and the concentration of calcium and magnesium ions, which can be used for the leaching of ion-type rare earth minerals.

[0033] According to an embodiment of the present invention, the extractant from the fourth regeneration can be reused in the above steps for continuous production.

[0034] According to the embodiments of the present invention, those skilled in the art can flexibly add or subtract extraction stages based on the type of metal elements in the rare earth industrial waste leachate and the types of elements extracted in each stage; for example, when the rare earth industrial waste leachate does not contain yttrium, the comprehensive recovery method does not need to include a fourth stage of extraction.

[0035] The present invention also provides a method for preparing the XM-SN extractant, comprising the following steps: mixing and activating the main component with an activator to obtain the XM-SN extractant;

[0036] According to an embodiment of the present invention, the molar fraction of the activator is 0.1-1, and the activation method is heating, mechanical stirring, mechanical grinding, ultrasound, microwave, ultraviolet irradiation, alkali activation, or radiation irradiation.

[0037] According to an embodiment of the present invention, the molar ratio of the main component to the activator is 1:(0.1-10); for example, it is 1:(0.5-6), and exemplary ratios are 1:1, 1:2, 1:3, 1:4, 1:5, and 1:9.

[0038] Beneficial effects

[0039] The method for comprehensive recovery of rare earth industrial waste in this invention uses XM-SN extractant, which can effectively separate thorium, iron, aluminum, rare earth elements, calcium, and magnesium in stages. The XM-SN extractant of this invention is simple to prepare, has good biocompatibility, low toxicity, and is reusable. It is a stable, efficient, and highly selective extractant. The extraction process does not require the addition of flammable and volatile diluents such as kerosene. The extraction process is free of emulsification and three-phase formation, and the phase separation rate is fast. The rare earth radioactive waste recovery process is simple, continuous, and can be automated. It achieves good separation results, with a separation coefficient greater than 10,000 for thorium and greater than 300 for aluminum. It can efficiently enrich rare earth elements, with high recovery rates for each element, high purity for each product, and low production costs, making it suitable for widespread application.

[0040] Terminology Definitions and Explanations

[0041] The term "long chain" refers to a straight-chain or branched hydrocarbon group (such as alkyl, alkenyl or alkynyl) having 2-40 carbon atoms, preferably a straight-chain or branched hydrocarbon group having 5-20 carbon atoms; more preferably a straight-chain or branched hydrocarbon group having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms. Detailed Implementation

[0042] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0043] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0044] Example 1: First, activator decanol and main component oleic acid were weighed at a molar ratio of 1:1 and mechanically stirred for 30 minutes. Then, TBP (tributyl phosphate), an antiemulsifier, was added at a volume fraction of 20% of the decanol and oleic acid mixture, and ultrasonically activated at room temperature to obtain XM-SN-1 extractant, which is a low-viscosity liquid at room temperature. Next, diisooctylamine and main component gemfibrozil were weighed at a molar ratio of 1:5 and mechanically stirred for 30 minutes to obtain XM-SN-2 extractant, which is also a low-viscosity liquid at room temperature.

[0045] Rare earth waste residue was obtained from the impurity removal residue generated during the production process of an ion-adsorption rare earth mine in Changting, Fujian Province. It was leached with hydrochloric acid, and the concentrations of each metal element were adjusted using appropriate metal chlorides to obtain a rare earth waste residue leachate. The concentrations of each element in the leachate are shown in Table 1. The pH of the leachate was adjusted to 3.0–3.1 using hydrochloric acid and sodium hydroxide. The prepared XM-SN-1 extractant was used in a two-stage extraction and two-stage washing process with the rare earth waste residue leachate at a volume ratio of 2:1 to obtain a first organic phase loaded with thorium and iron, and a first raffinate. The extraction rates of both thorium and iron were greater than 85%. The first organic phase loaded with thorium and iron was back-extracted with 1 mol / L oxalic acid to obtain thorium oxalate precipitate and iron oxalate solution (thorium and iron back-extraction solution). The regenerated first organic phase was recycled. The pH of the first raffinate was adjusted to 3.5–4.0 using sodium hydroxide to precipitate and remove the remaining trace amounts of thorium and iron. The precipitate was returned to the leaching process.

[0046] The first raffinate was used for the second stage of extraction, with the volume ratio of XM-SN-1 extractant to the first raffinate being 2:1. The pH was adjusted to 3.3 using sodium hydroxide, and the mixture was washed in multiple stages using 0.1 mol / L hydrochloric acid to obtain a second organic phase loaded with aluminum and a second raffinate. The aluminum extraction rate was greater than 98%, and the rare earth loss rate was less than 1%. The second organic phase loaded with aluminum was back-extracted using 0.1 mol / L hydrochloric acid to obtain a high-purity aluminum chloride solution (aluminum back-extraction solution). A small amount of rare earth elements were removed by precipitation with ammonium fluoride to obtain rare earth fluoride precipitate. The regenerated second organic phase was recycled.

[0047] The second raffinate was further extracted and separated from rare earth elements (REEs) by XM-SN-1 extractant, which also enriched the REEs. The volume ratio of XM-SN-1 extractant to the second raffinate was 1:1. Sodium hydroxide was used to adjust the pH during extraction, with the amount of sodium hydroxide being 3.2 times the molar amount of the REEs. Washing was performed with 0.001 mol / L hydrochloric acid. After extraction, a third organic phase loaded with REEs and a third raffinate were obtained, with an REE extraction rate greater than 99%. The REE-loaded third organic phase was back-extracted using 6 mol / L hydrochloric acid, with a volume ratio of the third organic phase to the back-extraction hydrochloric acid of 15:1. This two-stage back-extraction yielded a high-concentration REE solution (rare earth back-extraction solution). The third raffinate, after adjusting the pH and the concentration of calcium and magnesium ions, can be used for the leaching of ion-adsorption rare earth ores.

[0048] Calculations show that when XM-SN-1 extractant extracts thorium, the extraction rate of other elements is less than 2%; when extracting aluminum, the separation coefficient between aluminum and rare earth elements is greater than 300, and rare earth elements can be efficiently enriched; the separation coefficient between rare earth elements and calcium and magnesium is greater than 500.

[0049] The high-concentration rare earth solution obtained above was separated from heavy rare earth elements (Dy-Lu) and other rare earth elements (La-Tb and Y) by multi-stage extraction using XM-SN-2 extractant. The separation coefficient of XM-SN-2 extractant for Ho and Y was greater than 2.0, and the separation coefficient for Er and Y was greater than 2.33.

[0050] Table 1. Concentration of each element in the leachate of rare earth waste (mg / L)

[0051]

[0052] The embodiments of the technical solution of the present invention have been described above by way of example. It should be understood that the protection scope of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the protection scope of the claims of this application.

Claims

1. A method for comprehensive recycling of rare earth industrial waste, comprising the following steps: (1) First stage extraction: XM-SN extractant is added to the leachate of rare earth industrial waste to extract a first organic phase loaded with thorium and / or iron and a first raffinate; the first organic phase is back-extracted to obtain a thorium and / or iron back-extract. (2) Second stage extraction: XM-SN extractant is added to the first raffinate to extract the second organic phase loaded with aluminum and the second raffinate; the second organic phase is back-extracted to obtain the aluminum back-extract. (3) Third stage extraction: XM-SN extractant is added to the second raffinate to extract the third organic phase loaded with lanthanide rare earth and the third raffinate; the third organic phase is back-extracted to obtain the lanthanide rare earth back-extracting solution. (4) Fourth stage extraction: XM-SN extractant is added to the lanthanide rare earth back-extraction solution to extract the fourth organic phase loaded with yttrium and the fourth raffinate; the fourth organic phase is back-extracted to obtain the yttrium back-extraction solution; The XM-SN extractant in steps (1) to (3) is a combination of oleic acid, decanol and tributyl phosphate; the XM-SN extractant in step (4) is a combination of gemfibrozil and diisooctylamine; The molar ratio of oleic acid to decanol is 1:(0.5-6), and the tributyl phosphate accounts for 10-50% of the volume fraction of oleic acid and decanol. The molar ratio of gemfibrozil to diisooctylamine is 1:(0.5-6).

2. The method according to claim 1, characterized in that, The rare earth industrial waste leaching solution is a leaching solution obtained by leaching with one or more of hydrochloric acid, nitric acid and sulfuric acid. And / or, the pH of the leachate is 1-3.5; And / or, the volume ratio of the XM-SN extractant to the rare earth industrial waste leachate is 0.1-10; And / or, the components in the leachate from rare earth industrial waste are selected from at least one of thorium, iron, aluminum, rare earth, calcium, magnesium and / or rare earth elements; And / or, the extraction is a countercurrent cascade extraction.

3. The method according to claim 1, characterized in that, In step (1), the first organic phase loaded with thorium and / or iron is back-extracted using an inorganic acid or an organic acid to obtain the thorium and / or iron back-extract and the first regenerated XM-SN extractant; the inorganic acid or organic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride; And / or, the concentration of the inorganic or organic acid is 1-6 mol / L; In step (1), the pH of the first raffinate is adjusted to 3.5-4.0 using one or more of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate to remove any remaining trace amounts of thorium and / or iron before being used for the second stage of extraction.

4. The method according to claim 1, characterized in that, In step (2), the pH value of the equilibrium extraction system is adjusted online using an alkaline compound in the second stage of extraction. The alkaline compound is selected from at least one of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate. And / or, the amount of the alkaline compound used is 2 to 4 times the molar amount of aluminum; And / or, the pH value is in the range of 3.0 to 3.

75.

5. The method according to claim 1, characterized in that, In step (2), the second stage of extraction uses an inorganic acid or an organic acid to wash the extracted organic phase to obtain the second organic phase; the inorganic acid or organic acid is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride. And / or, the concentration of the inorganic or organic acid is 0.01-0.2 mol / L.

6. The method according to claim 1, characterized in that, In step (2), the second organic phase loaded with aluminum is back-extracted using an inorganic acid or an organic acid to obtain the aluminum back-extract and the second regenerated XM-SN extractant; the inorganic acid or organic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride. And / or, the concentration of the inorganic or organic acid is 0.01-1 mol / L; And / or, the aluminum back-extraction solution uses one or more of sodium fluoride, hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, aluminum fluoride, and sodium fluoroaluminate to remove trace amounts of rare earth elements.

7. The method according to claim 1, characterized in that, In step (3), the pH value of the equilibrium extraction system is adjusted online using an alkaline compound in the third stage of extraction. The alkaline compound is selected from at least one of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate. And / or, the amount of the alkaline compound used is 2 to 4 times the molar amount of the rare earth element; And / or, the pH value is in the range of 4.0 to 6.

5.

8. The method according to claim 1, characterized in that, In step (3), the third stage of extraction uses an inorganic acid or an organic acid to wash the extracted organic phase to obtain the third organic phase; the inorganic acid or organic acid is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride. And / or, the concentration of the inorganic or organic acid is 0.0001-0.2 mol / L.

9. The method according to claim 1, characterized in that, In step (3), the third organic phase loaded with lanthanide rare earth is back-extracted using one or more inorganic or organic acids to obtain the lanthanide rare earth back-extraction solution and the third regeneration extractant; the inorganic or organic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride. And / or, the concentration of the inorganic or organic acid is 0.5-8 mol / L.

10. The method according to claim 1, characterized in that, In step (4), the pH value of the equilibrium extraction system is adjusted online using an alkaline compound in the fourth stage of extraction. The alkaline compound is selected from at least one of sodium hydroxide, sodium carbonate, calcium oxide, magnesium oxide, ammonia, and ammonium bicarbonate. And / or, the pH value is in the range of 3-4.

11. The method according to claim 1, characterized in that, In step (4), the fourth stage of extraction uses an inorganic acid or an organic acid to wash the extracted organic phase to obtain the fourth organic phase; the inorganic acid or organic acid is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride.

12. The method according to claim 1, characterized in that, In step (4), the fourth organic phase loaded with yttrium is back-extracted using one or more inorganic or organic acids to obtain the yttrium back-extract and the fourth regenerated XM-SN extractant; the inorganic or organic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, propionic acid, butyric acid, EDTA, citric acid, malic acid, and betaine hydrochloride.

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