Method for extracting and separating rare earth and aluminum from acetic acid solution by utilizing dynamic difference

Abstract

The invention provides a method for extracting and separating rare earth and aluminum from an acetic acid solution by using dynamic difference, which comprises the following steps: extracting the acetic acid solution containing rare earth and aluminum for 5-30 seconds by using an organic phase containing a phosphoric acid extracting agent to realize selective separation of rare earth and aluminum ions to obtain a rare earth-loaded organic phase and an aluminum-containing raffinate; the phosphoric acid-containing extraction agent comprises a P204 extraction agent and / or a P507 extraction agent; in the acetic acid solution containing rare earth and aluminum, the concentration sum of acetic acid and acetate is 0.3 mol / L-3. 5mol / L; the pH value of the acetic acid solution containing rare earth and aluminum is 4.0-5.0. As the coordination constant of aluminum ions and acetate is larger than that of rare earth ions and acetate, when the method is used for treating the acetic acid solution containing rare earth and aluminum, rare earth can be directly extracted and separated from the solution, and meanwhile, the method has the advantages that the operation is simple and convenient, and the method can be realized by using existing conventional equipment.

Description

Technical Field

[0001] This invention belongs to the field of rare earth separation technology, and relates to a method for extracting and separating rare earth elements and aluminum from acetic acid solution by utilizing kinetic differences. Background Technology

[0002] Medium and heavy rare earth elements have wide applications in optoelectronic fields such as laser media, radiation sources, scintillation crystals, and magnetic materials, and play an irreplaceable role in advanced technologies. Therefore, the purification of medium and heavy rare earth elements is very important.

[0003] Because rare earth elements exist in minerals at low concentrations and are accompanied by other impurities such as Al and Fe, and because rare earth elements and aluminum have similar properties, it is very difficult to separate and purify rare earth elements from the mixed rare earth products (containing rare earth and aluminum impurities) obtained by decomposing rare earth concentrates using general chemical methods such as stepwise precipitation.

[0004] To separate aluminum ions in rare earth solutions, some technical solutions for separating rare earth and aluminum have been disclosed in the prior art.

[0005] For example, CN105624440A discloses the use of hydroxyquinoline or hydroxyquinoline derivatives to treat rare earth solutions containing large amounts of aluminum ions, achieving the removal of aluminum ions from the rare earth solution. CN106367620A discloses a method for selectively recovering rare earths from low-concentration rare earth solutions using a primary amine extractant; through two-stage countercurrent extraction, the rare earth concentration can be reduced to below 0.5 mg / L, while the extraction efficiency for aluminum is low. WO2018 / 028543A1 discloses a method for extracting and recovering rare earths from low-concentration rare earth solutions, using a non-saponifiable organic extractant for centrifugal extraction, followed by centrifugal back-extraction of the supported organic phase using an inorganic acid to obtain a rare earth-enriched solution. However, although the above three technical solutions have some effect on the separation of rare earths and aluminum, the separation methods are relatively complex, and the required reagents or equipment are relatively expensive.

[0006] For example, CN117051237A discloses a method for reducing aluminum impurities in a mixed rare earth chloride solution. This method involves adding sodium fluoride, heating to above 90°C, stirring the reaction for 1-3 hours, allowing it to stand, and then filtering to obtain cryolite, thus removing aluminum. However, this method for reducing aluminum impurities in a mixed rare earth chloride solution may leave fluorine residue, affecting subsequent rare earth separation.

[0007] For example, CN118480701A discloses a method for extracting aluminum from a high-alumina solution. This method involves mixing an organic phase containing ionic liquid with a high-alumina rare earth solution for extraction, resulting in an aluminum-rich solution. However, the above method mainly focuses on selective aluminum removal and is difficult to directly extract and separate rare earth elements from aluminum-containing solutions.

[0008] Existing methods for extracting and separating rare earth and aluminum ions from solutions containing these ions all have certain drawbacks. These include the difficulty in directly extracting and separating rare earths from aluminum-containing solutions, the inability to achieve the desired separation efficiency for practical applications, and the complexity of the methods and the expense of the required reagents or equipment. Therefore, screening for a novel acid medium to develop a method for extracting and separating rare earths and aluminum from acetic acid solutions is crucial for improving the extraction and separation efficiency and reducing costs. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a method for extracting and separating rare earth elements and aluminum from acetic acid solution using kinetic differences. In this invention, an organic phase containing a phosphoric acid extractant is used to extract the acetic acid solution containing rare earth elements and aluminum for 5 to 30 seconds. Since the coordination constant of aluminum ions with acetate ions (logK=3.3) is larger than that of rare earth ions with acetate ions (logK=2.5~2.8) and there is a certain difference, rare earth ions are more likely to combine with phosphoric acid extractant molecules and enter the organic phase within a shorter mixing time, thus achieving preferential extraction of rare earth elements. Therefore, processing the acetic acid solution containing rare earth elements and aluminum using the above method can not only directly extract and separate rare earth elements from the solution, but also has excellent separation effect on rare earth ions and aluminum ions. At the same time, it also has the advantages of simple operation and can be implemented using existing conventional equipment.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences, the method comprising:

[0012] An organic phase containing phosphoric acid extractant was extracted with an acetic acid solution containing rare earth elements and aluminum for 5 to 30 seconds to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate.

[0013] The phosphoric acid extractant includes P204 extractant and / or P507 extractant;

[0014] In the acetic acid solution containing rare earth elements and aluminum, the sum of the concentrations of acetic acid and acetate ions is 0.3 mol / L to 3.5 mol / L; the pH of the acetic acid solution containing rare earth elements and aluminum is 4.0 to 5.0.

[0015] In this invention, the extraction time is defined as the mixing time of the organic phase and the aqueous phase.

[0016] In this invention, the mixing time for extraction is 5s to 30s, for example, it can be 5s, 8s, 10s, 12s, 15s, 18s, 20s, 22s, 25s, 28s or 30s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] In this invention, the extraction time affects the rare earth extraction rate and the separation effect between rare earth and aluminum; when the extraction time of the organic phase containing phosphoric acid extractant with the acetic acid solution containing rare earth and aluminum is 5s~30s, a high rare earth extraction rate and a high separation coefficient β can be achieved. RE / Al This is because when the mixing time is too short, the contact between rare earth ions and extractant molecules is insufficient, resulting in a decrease in the rare earth extraction rate. When the mixing time is longer, the probability of contact between aluminum ions and extractant molecules increases, leading to an increase in the aluminum ion extraction rate, thus causing the separation coefficient β to rise. RE / Al decline.

[0018] In this invention, compared with other extractants, using P204 and / or P507 extractants to extract acetic acid solutions containing rare earth elements and aluminum can improve the separation effect of rare earth elements and aluminum. This is because the molecular structures of Cyanex272 and Versatic10 are different from those of P204 and P507, resulting in significant differences in their extraction capabilities for rare earth elements and aluminum.

[0019] In this invention, the sum of the concentrations of acetic acid and acetate ions in the acetic acid solution containing rare earth elements and aluminum is 0.3 mol / L to 3.5 mol / L; and the pH of the acetic acid solution containing rare earth elements and aluminum is 4.0 to 5.0.

[0020] According to existing technology, acetic acid is a weak electrolyte. In acetic acid solutions containing rare earth elements and aluminum, acetic acid is partially ionized into acetate ions and hydrogen ions, while part of it remains unionized acetic acid.

[0021] In this invention, the sum of the concentrations of acetic acid and acetate ions in the acetic acid solution containing rare earth elements and aluminum is 0.3 mol / L to 3.5 mol / L. For example, it can be 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.2 mol / L, 2.5 mol / L, 2.7 mol / L, 3.0 mol / L, 3.2 mol / L, or 3.5 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] In this invention, the pH of the acetic acid solution containing rare earth elements and aluminum is 4.0 to 5.0, for example, it can be 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] In this invention, an organic phase containing phosphoric acid extractant is used to extract an acetic acid solution containing rare earth elements and aluminum for 5 to 30 seconds. Since the coordination constant of aluminum ions with acetate (logK=3.3) is larger than that of rare earth ions with acetate (logK=2.5~2.8) and there is a certain difference, rare earth ions are more likely to combine with phosphoric acid extractant molecules and enter the organic phase within a shorter mixing time, thus achieving preferential extraction of rare earth elements. Therefore, the method described above can not only directly extract and separate rare earth elements from the solution, but also has excellent separation effect on rare earth ions and aluminum ions. At the same time, it has the advantages of simple operation and can be implemented using existing conventional equipment.

[0024] Preferably, in the acetic acid solution containing rare earth elements and aluminum, the rare earth ions include lanthanide ions and yttrium ions.

[0025] Preferably, the lanthanide ions include any one or at least two combinations of lanthanum ions, cerium ions, praseodymium ions, neodymium ions, samarium ions, europium ions, gadolinium ions, terbium ions, dysprosium ions, holmium ions, erbium ions, thulium ions, ytterbium ions, or lutetium ions. Typical but non-limiting combinations include combinations of lanthanum ions and cerium ions, combinations of neodymium ions and samarium ions, combinations of europium ions and gadolinium ions, combinations of terbium ions and dysprosium ions, or combinations of lanthanum ions, neodymium ions, and gadolinium ions.

[0026] Preferably, in the organic phase containing the phosphoric acid extractant, the organic diluent includes any one or a combination of at least two of kerosene, cyclohexane, or n-heptane. Typical but non-limiting combinations include a combination of kerosene and cyclohexane, a combination of cyclohexane and n-heptane, a combination of kerosene and n-heptane, or a combination of kerosene, cyclohexane, and n-heptane.

[0027] Preferably, in the organic phase containing the phosphoric acid extractant, the concentration of the phosphoric acid extractant is 0.15 mol / L to 1.5 mol / L, for example, it can be 0.15 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] Preferably, in the acetic acid solution containing rare earth and aluminum, the concentration of rare earth ions is 0.1 mol / L to 1 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1.0 mol / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] Preferably, in the acetic acid solution containing rare earth elements and aluminum, the concentration of aluminum ions is 0.001 mol / L to 0.1 mol / L, for example, it can be 0.001 mol / L, 0.005 mol / L, 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0030] Preferably, the extraction temperature is 5℃~60℃, for example, it can be 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃ or 60℃, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] Preferably, the extraction method includes countercurrent extraction.

[0032] Preferably, the countercurrent extraction includes at least two stages of countercurrent extraction.

[0033] As a preferred embodiment of the method described in this invention, the method includes:

[0034] At 5℃~60℃, an organic phase containing phosphoric acid extractant was subjected to countercurrent extraction for 5s~30s into an acetic acid solution containing rare earth elements and aluminum to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate.

[0035] The organic phase containing the phosphoric acid extractant includes P204 extractant and / or P507 extractant with a concentration of 0.15 mol / L to 1.5 mol / L, and the organic diluent includes any one or a combination of at least two of kerosene, cyclohexane or n-heptane.

[0036] The acetic acid solution containing rare earth elements and aluminum has a pH of 4.0 to 5.0, and the sum of the concentrations of acetic acid and acetate ions is 0.3 mol / L to 3.5 mol / L. In the acetic acid solution containing rare earth elements and aluminum, the rare earth ions include lanthanide ions and yttrium ions, the concentration of rare earth ions is 0.1 mol / L to 1 mol / L, and the concentration of aluminum ions is 0.001 mol / L to 0.1 mol / L.

[0037] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] In this invention, an organic phase containing phosphoric acid extractant is used to extract an acetic acid solution containing rare earth elements and aluminum. Due to the difference in coordination ability between aluminum ions and rare earth ions with acetate ions, rare earth ions are more likely to combine with phosphoric acid extractant molecules and enter the organic phase within a shorter mixing time, thus achieving preferential extraction of rare earth elements. Therefore, treating an acetic acid solution containing rare earth elements and aluminum using the above method can not only directly extract and separate rare earth elements from the solution, but also has excellent separation effect on rare earth ions and aluminum ions. At the same time, it also has the advantages of simple operation and can be implemented using existing conventional equipment. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0041] Example 1

[0042] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. The method includes:

[0043] At 25°C, a two-stage countercurrent extraction of acetic acid solution containing rare earth elements and aluminum was performed for 30 seconds using an organic phase containing 1.5 mol / L P507 extractant (kerosene was used as the diluent in the organic phase) to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate.

[0044] The pH of the acetic acid solution containing rare earth elements and aluminum is 4.0, and the sum of the concentrations of acetic acid and acetate ions is 3.5 mol / L. The ion concentrations of various elements contained in the acetic acid solution containing rare earth elements and aluminum are shown in Table 1.

[0045] Table 1

[0046]

[0047] Example 2

[0048] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. The method includes:

[0049] At 45°C, an acetic acid solution containing rare earth elements and aluminum was subjected to a four-stage countercurrent extraction for 5 seconds using an organic phase containing 0.15 mol / L P507 extractant (with cyclohexane as the diluent in the organic phase) to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate.

[0050] The acetic acid solution containing rare earth elements and aluminum has a pH of 5.0, and the sum of the concentrations of acetic acid and acetate ions is 0.3 mol / L. The concentrations of various ions contained in the acetic acid solution containing rare earth elements and aluminum are shown in Table 2.

[0051] Table 2

[0052]

[0053] Example 3

[0054] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. The method includes:

[0055] At 5°C, a solution of acetic acid containing rare earth elements and aluminum was subjected to a three-stage countercurrent extraction for 20 seconds using an organic phase containing a P204 extractant at a concentration of 0.75 mol / L (the diluent in the organic phase was n-heptane) to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate.

[0056] The pH of the acetic acid solution containing rare earth elements and aluminum is 4.7, and the sum of the concentrations of acetic acid and acetate ions is 1.65 mol / L. The concentrations of various ions contained in the acetic acid solution containing rare earth elements and aluminum are shown in Table 3.

[0057] Table 3

[0058]

[0059] Example 4

[0060] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. The method includes:

[0061] At 60°C, a two-stage countercurrent extraction of acetic acid solution containing rare earth elements and aluminum was performed for 30 seconds using an organic phase containing P507 extractant at a concentration of 0.75 mol / L (kerosene as the diluent in the organic phase), to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate.

[0062] The pH of the acetic acid solution containing rare earth elements and aluminum is 4.4, and the sum of the concentrations of acetic acid and acetate ions is 1.65 mol / L. The concentrations of various ions contained in the acetic acid solution containing rare earth elements and aluminum are shown in Table 4.

[0063] Table 4

[0064]

[0065] Example 5

[0066] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. Except for the concentration of P507 extractant in the organic phase containing P507 extractant being 0.1 mol / L, the rest is the same as in Example 2.

[0067] Example 6

[0068] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. Except for the concentration of P507 extractant in the organic phase containing P507 extractant being 2.0 mol / L, the rest is the same as in Example 2.

[0069] Example 7

[0070] This embodiment provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. Except for the single-stage extraction of the acetic acid solution containing rare earth elements and aluminum, the rest is the same as in Example 4.

[0071] Comparative Example 1

[0072] This comparative example provides a method for handling rare earth elements and aluminum in hydrochloric acid solution. Except for replacing the acetic acid solution containing rare earth elements and aluminum with a hydrochloric acid solution containing rare earth elements and aluminum, and ensuring that the pH of the hydrochloric acid solution containing rare earth elements and aluminum is also 4.0, the concentration of chloride ions is 3.5 mol / L, and the concentrations of rare earth ions and aluminum ions remain unchanged, everything else is the same as in Example 1.

[0073] Comparative Example 2

[0074] This comparative example provides a method for handling rare earth elements and aluminum in a sulfuric acid solution. Except for replacing the acetic acid solution containing rare earth elements and aluminum with a sulfuric acid solution containing rare earth elements and aluminum, and ensuring that the pH of the sulfuric acid solution containing rare earth elements and aluminum is also 4.0, the concentration of sulfate ions is 0.2 mol / L, and the concentrations of rare earth ions and aluminum ions remain unchanged, everything else is the same as in Example 2.

[0075] Comparative Example 3

[0076] This comparative example provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution. Except that the "organic phase containing P507 extractant at a concentration of 1.5 mol / L" is replaced with the "organic phase containing Versatic10 extractant at a concentration of 1.5 mol / L", the rest is the same as in Example 1.

[0077] Comparative Example 4

[0078] This comparative example provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution. Except for replacing "an organic phase containing 1.5 mol / L P507 extractant (with kerosene as the diluent in the organic phase)" with "an organic phase containing 1.5 mol / L Cyanex272 extractant (with kerosene as the diluent in the organic phase)", the method is the same as in Example 1.

[0079] Comparative Example 5

[0080] This comparative example provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. Except for performing a two-stage countercurrent extraction of the acetic acid solution containing rare earth elements and aluminum for 2 seconds, the method is the same as in Example 1.

[0081] Comparative Example 6

[0082] This comparative example provides a method for extracting and separating rare earth elements and aluminum from an acetic acid solution using kinetic differences. Except for performing a two-stage countercurrent extraction of the acetic acid solution containing rare earth elements and aluminum for 60 seconds, the method is the same as in Example 1.

[0083] Using the methods for extracting and separating rare earth elements and aluminum from acetic acid solution based on kinetic differences provided in Example 1 and Comparative Example 1, and for separating rare earth elements and aluminum from hydrochloric acid solution and sulfuric acid solution, the rare earth and aluminum-containing acetic acid solution, hydrochloric acid solution, and sulfuric acid solution of the examples and comparative examples were subjected to rare earth and aluminum extraction and separation. The rare earth extraction rate was calculated based on the concentrations of each ion in the obtained rare earth-loaded organic phase and aluminum-containing raffinate. aluminum The extraction rate is shown in Table 5. The calculation method is as follows: Ion extraction rate (%) = [(Ion concentration in the initial aqueous phase × initial aqueous phase volume - Ion concentration in the raffinate × raffinate volume) / (Ion concentration in the initial aqueous phase × initial aqueous phase volume)] × 100%, where the initial aqueous phase volume and the raffinate volume are measured by measuring cylinder.

[0084] Table 5

[0085]

[0086] The total rare earth extraction rate is then calculated using the extraction rates of each rare earth element. The calculation method is as follows: Total rare earth extraction rate = (total molar concentration of rare earth elements in the organic phase × volume of the organic phase) / (total molar concentration of rare earth elements in the initial aqueous phase × volume of the initial aqueous phase), where the total molar concentration of rare earth elements is equal to the sum of the molar concentrations of each rare earth element. The calculated total rare earth extraction rate is shown in Table 6.

[0087] The separation coefficients of rare earth and aluminum are then calculated using the total rare earth extraction rate and the Al ion extraction rate. The calculation method is as follows: Rare earth partition ratio = total rare earth concentration in the organic phase / total rare earth concentration in the raffinate; Aluminum partition ratio = aluminum concentration in the organic phase / aluminum concentration in the raffinate; Separation coefficient of rare earth and aluminum = rare earth partition ratio / aluminum partition ratio. The calculated separation coefficient β is then used to determine the separation coefficient of rare earth and aluminum. RE / Al As shown in Table 6.

[0088] Table 6

[0089]

[0090] From Tables 5 and 6, we can obtain:

[0091] (1) Using the method provided in Examples 1-4 to extract and separate rare earth and aluminum from acetic acid solution by utilizing kinetic differences, an acetic acid solution containing rare earth and aluminum can be extracted, which can achieve the separation of rare earth and aluminum in acetic acid solution, with a high extraction rate of rare earth ions and a high separation coefficient of rare earth and aluminum.

[0092] (2) By comparing Example 2 with Examples 5 and 6, it can be seen that in the present invention, the concentration of phosphoric acid extractant in the organic phase containing phosphoric acid extractant affects the extraction rate and separation effect of rare earth and aluminum; when the concentration of phosphoric acid extractant is 0.15mol / L~1.5mol / L, it can achieve both a high rare earth extraction rate and a high separation coefficient β. RE / Al This is because if the concentration of the extractant is too low, the extraction rate of rare earth elements will decrease; if the concentration of the extractant is too high, the extraction rate of aluminum will increase, thus reducing the separation coefficient between rare earth elements and aluminum.

[0093] (3) By comparing Example 4 and Example 7, it can be seen that in this invention, compared with single-stage extraction, countercurrent extraction is beneficial to improving the rare earth extraction rate and the separation effect of rare earth and aluminum. This is because the organic phase and the aqueous phase flow continuously in opposite directions in countercurrent extraction, which can achieve multiple sufficient contacts and mass transfer between the two phases. Rare earth ions can continuously transfer and accumulate to the organic phase in multiple contacts, while aluminum ions are more retained in the aqueous phase, which effectively amplifies the difference in extraction capacity between the two. In contrast, single-stage extraction is only a single contact, and the mass transfer is insufficient, and the separation selectivity is limited. Therefore, countercurrent extraction can significantly improve the separation effect.

[0094] (4) By comparing Example 1 with Comparative Examples 1 and 2, it can be seen that, taking the most difficult-to-separate lanthanum and aluminum as an example, in the acetic acid system (i.e., extracting with an organic solution containing phosphoric acid extractant and an acetic acid solution containing rare earth and aluminum), after two-stage countercurrent extraction, the separation coefficient of lanthanum and aluminum can reach 102.

[0095] In the hydrochloric acid system (i.e., extracting rare earth and aluminum solutions with an organic phase containing phosphoric acid extractant), since the extraction order of aluminum ions is between light rare earths, it means that aluminum must be removed before rare earth separation. If aluminum is not removed, the separation of rare earth and aluminum cannot be achieved.

[0096] In the sulfuric acid system, although rare earth elements and aluminum have a certain separation effect, their coordination ability with sulfate ions is weak and the difference is small, resulting in a small separation coefficient between rare earth elements and aluminum.

[0097] Therefore, in this invention, the organic phase containing phosphoric acid extractant is used to extract acetic acid solution containing rare earth elements and aluminum. Since the coordination constant of aluminum ions with acetate ions (logK=3.3) is larger than that of rare earth ions with acetate ions (logK=2.5~2.8) and there is a certain difference, rare earth ions are more likely to combine with phosphoric acid extractant molecules and enter the organic phase within a shorter mixing time, thus achieving preferential extraction of rare earth elements. Therefore, the method described above can not only directly extract and separate rare earth elements from the solution, but also has excellent separation effect on rare earth ions and aluminum ions. At the same time, it has the advantages of simple operation and can be implemented using existing conventional equipment.

[0098] (5) By comparing Example 1 with Comparative Examples 3 and 4, it can be seen that in this invention, compared with other extractants, when using P204 extractant and / or P507 extractant to extract acetic acid solution containing rare earth and aluminum, the separation effect of rare earth and aluminum can be improved. This is because the molecular structures of Cyanex272, Versatic10 and P204, P507 are different, which makes their extraction capabilities for rare earth and aluminum quite different.

[0099] (6) By comparing Example 1 with Comparative Examples 5 and 6, it can be seen that in this invention, the extraction time affects the rare earth extraction rate and the separation effect of rare earth and aluminum; when the extraction time of organic solvent containing phosphoric acid extractant with acetic acid solution containing rare earth and aluminum is 5s~30s, a high rare earth extraction rate and a high separation coefficient β can be achieved. RE / Al This is because when the mixing time is too short, the contact between rare earth ions and extractant molecules is insufficient, resulting in a decrease in the rare earth extraction rate. When the mixing time is longer, the probability of contact between aluminum ions and extractant molecules increases, leading to an increase in the aluminum ion extraction rate, thus causing the separation coefficient β to rise. RE / Al decline.

[0100] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for extracting and separating rare earth elements and aluminum from acetic acid solution using kinetic differences, characterized in that, The method includes: An organic phase containing phosphoric acid extractant was extracted with an acetic acid solution containing rare earth elements and aluminum for 5 to 30 seconds to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate. The phosphoric acid extractant includes P204 extractant and / or P507 extractant; In the acetic acid solution containing rare earth elements and aluminum, the sum of the concentrations of acetic acid and acetate ions is 0.3 mol / L to 3.5 mol / L; the pH of the acetic acid solution containing rare earth elements and aluminum is 4.0 to 5.

0.

2. The method according to claim 1, characterized in that, In the acetic acid solution containing rare earth elements and aluminum, the rare earth ions include lanthanide ions and yttrium ions.

3. The method according to claim 2, characterized in that, The lanthanide ions include any one or a combination of at least two of the following: lanthanum ion, cerium ion, praseodymium ion, neodymium ion, samarium ion, europium ion, gadolinium ion, terbium ion, dysprosium ion, holmium ion, erbium ion, thulium ion, ytterbium ion, or lutetium ion.

4. The method according to claim 1, characterized in that, In the organic phase containing the phosphoric acid extractant, the organic diluent includes any one or a combination of at least two of kerosene, cyclohexane, or n-heptane.

5. The method according to claim 1, characterized in that, In the organic phase containing the phosphoric acid extractant, the concentration of the phosphoric acid extractant is 0.15 mol / L to 1.5 mol / L.

6. The method according to claim 1, characterized in that, In the acetic acid solution containing rare earth elements and aluminum, the concentration of rare earth ions is 0.1 mol / L to 1 mol / L.

7. The method according to claim 1, characterized in that, In the acetic acid solution containing rare earth elements and aluminum, the concentration of aluminum ions is 0.001 mol / L to 0.1 mol / L.

8. The method according to any one of claims 1 to 7, characterized in that, The extraction method includes countercurrent extraction.

9. The method according to claim 8, characterized in that, The countercurrent extraction includes at least two stages of countercurrent extraction.

10. The method according to claim 1, characterized in that, The method includes: At 5℃~60℃, an organic phase containing phosphoric acid extractant was subjected to countercurrent extraction for 5s~30s into an acetic acid solution containing rare earth elements and aluminum to obtain an organic phase loaded with rare earth elements and an aluminum-containing raffinate. The organic phase containing the phosphoric acid extractant includes P204 extractant and / or P507 extractant with a concentration of 0.15 mol / L to 1.5 mol / L, and the organic diluent includes any one or a combination of at least two of kerosene, cyclohexane or n-heptane. The acetic acid solution containing rare earth elements and aluminum has a pH of 4.0 to 5.0, and the sum of the concentrations of acetic acid and acetate ions is 0.3 mol / L to 3.5 mol / L. In the acetic acid solution containing rare earth elements and aluminum, the rare earth ions include lanthanide ions and yttrium ions, the concentration of rare earth ions is 0.1 mol / L to 1 mol / L, and the concentration of aluminum ions is 0.001 mol / L to 0.1 mol / L.

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