Method for extracting and separating rare earth and iron under assistance of photo-reduction

Abstract

The invention provides a method for extracting and separating rare earth and iron under the assistance of photoreduction, which comprises the following steps: carrying out reduction reaction on Fe < 3 + > in a rare earth and iron mixed solution by using illumination and a quenching agent to obtain a reduction solution; and extracting the reducing solution by using the extracting solution to obtain a rare earth organic phase and an iron-rich raffinate. According to the method provided by the invention, valence state regulation and control are carried out on ferric ions in the rare earth solution, iron is reduced into ferrous ions, the problem that the ferric ions are easy to extract at the same time when the rare earth ions are extracted is solved, and the separation effect of iron and rare earth elements is improved; the reduction of iron ions adopts a photo-reduction method, the process is simple, the reduction effect is good, a reducing agent does not need to be introduced, a quenching agent is easy to remove, introduction of impurities difficult to separate is avoided, and an extracting agent after reaction can be recycled.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology and relates to a method for separating rare earth elements and iron, particularly a method for separating rare earth elements and iron using photoreduction-assisted extraction. Background Technology

[0002] Rare earth elements are widely used in various fields such as catalysis, hydrogen storage, optical fiber, communications, and gas separation, and are an important strategic resource. However, rare earth raw materials often contain many impurities, and purity issues greatly limit the application of rare earth resources.

[0003] Separating rare earth elements from iron is a challenging aspect of rare earth raw materials. Currently, rare earth extraction typically employs extraction methods. Extraction utilizes the different solubilities of target substances in different solvents to separate mixtures. From an extraction perspective, Fe... 3+ It is a component that is extremely easy to extract, readily extracted by various types of extractants, and often enters the organic phase before other metals. Organophosphorus extractants, commonly used for extracting rare earth ions, are effective for Fe... 3+ Similarly, due to its strong selectivity, the presence of iron significantly interferes with the separation of rare earth elements. CN116676486A discloses a method for recovering iron, phosphorus, and rare earth elements from rare earth waste. This method involves dissolving the rare earth waste and first extracting iron and phosphoric acid sequentially using solvent extraction, then recovering the rare earth elements through a water leaching process. While this method extracts iron first, it also easily extracts rare earth elements during the extraction process, resulting in poor separation of iron and rare earth elements, and the process steps are relatively cumbersome. CN115161499A discloses a one-step extraction method for separating and recovering rare earth elements and iron. This method uses trioctylmethyl oxalate ammonium as the extractant to extract iron, obtaining a rare earth oxalate raffinate extract and an iron-rich organic phase, thus separating the rare earth elements from the iron. However, this direct extraction method also results in poor separation of rare earth elements and iron.

[0004] Therefore, given the shortcomings of existing technologies, there is a need to provide a method for separating rare earth elements and iron using photoreduction-assisted extraction to reduce the iron extraction rate. Summary of the Invention

[0005] The purpose of this invention is to provide a method for separating rare earth elements and iron using photoreduction-assisted extraction, thereby solving the problem of Fe... 3+ It is easy to extract the interference of rare earth element separation, and realize the separation of rare earth and iron elements.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a method for separating rare earth elements and iron using photoreduction-assisted extraction, the method comprising the following steps:

[0008] (1) Using light and quenching agents, Fe in the rare earth iron mixed solution is removed. 3+ A reduction reaction occurs, yielding a reduced solution;

[0009] (2) The reduced solution obtained in step (1) is extracted with the extraction liquid to obtain rare earth organic phase and iron-rich raffinate.

[0010] In acid leaching solutions of rare earth oxides or leaching solutions of ionic rare earth minerals, which contain rare earth ions, rare earths are generally present as trivalent ions (RE). 3+ It exists, and Fe is present at the same time. 3+ Coexistence, the two ions have the same valence and similar properties, Fe 3+ It is very easy for it to be extracted simultaneously with rare earth ions, which affects the purity of the separated rare earth ions.

[0011] This invention employs a photoreduction method to control the valence state of iron, thereby reducing the Fe content in the solution system. 3+ Reduced to Fe 2+ This addresses the issue of selective extraction of rare earth ions based on valence state, and then further extracts rare earth ions using extraction methods, reducing Fe content. 3+ Entrainment enhances the separation of iron and rare earth elements. Simultaneously, a photoreduction method is employed, where ferric ions in the aqueous solution are converted into ferrous ions and hydroxyl radicals under the influence of light. Alcohols and other quenchers are used to quench the hydroxyl radicals, preventing the oxidation of ferrous iron. Furthermore, the photoreduction method uses only light and quenchers, avoiding the introduction of difficult-to-separate impurities such as reducing agents or catalysts, thus not affecting subsequent extraction processes.

[0012] The rare earth iron mixed solution includes acid leaching solution of rare earth oxides and / or ion-type rare earth ore leaching solution.

[0013] Preferably, the mass concentration ratio of rare earth ions to iron ions in the rare earth iron mixed solution is RE 3+ / Fe 3+ The ratio is 1:1 to 10000:1, for example, it can be 1:1, 5:1, 10:1, 50:1, 100:1, 500:1, 1000:1, 3000:1, 5000:1, 8000:1 or 10000:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the anions in the rare earth iron mixed solution include Cl-. - and / or NO3 - .

[0015] Preferably, the pH of the rare earth iron mixed solution is <7, for example, it can be 0, 1, 2, 3, 4, 5, 6 or 6.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, the wavelength of the illumination is 100-1000nm, for example, it can be 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the power of the illumination is 10-1000W, for example, it can be 10W, 50W, 100W, 200W, 400W, 500W, 600W, 800W or 1000W, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 200-600W.

[0018] Preferably, the quencher comprises any one or a combination of at least two of ethanol, isopropanol, tert-butanol, methanol, n-heptanol, n-octanol, or glycerol. Typical but non-limiting combinations include combinations of ethanol and isopropanol, ethanol and n-heptanol, n-octanol and glycerol, or combinations of ethanol, isopropanol, methanol, and glycerol. Preferably, it is a combination of any one or at least two of methanol, ethanol, or tert-butanol.

[0019] Preferably, the amount of quenching agent used is reduced Fe. 3+ The required theoretical dosage is 1 to 5000 times, for example, it can be 1, 10, 50, 100, 500, 1000 or 5000 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 100 to 2000 times.

[0020] In this invention, the following reactions mainly occur during the photoreduction process:

[0021]

[0022] C x H y O z +(4x+y-2z) · OH→xCO2↑+(2x+yz)H2O

[0023] Based on the above reaction formula, the theoretical amount of quencher required is calculated. According to literature reports, a large amount of quencher is needed to effectively remove ·OH, thereby preventing the formation of Fe. 2+ quilt · OH oxidation to regenerate Fe 3+ The amount of quenching agent used is usually more than 100 times the theoretical value.

[0024] Preferably, the reduction reaction time is 0.5-5h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.5-2h.

[0025] Preferably, the temperature of the reduction reaction is 20-80℃, for example, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the extract comprises an extractant and a diluent.

[0027] Preferably, the concentration of the extractant in the extract solution is 0.01-100%, for example, it can be 0.01%, 1%, 5%, 10%, 20%, 40%, 50%, 60%, 80% or 100%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.01-90%.

[0028] Preferably, the extractant comprises an organophosphorus extractant.

[0029] Preferably, the organophosphorus extractant comprises any one or a combination of at least two of the following: P507 (2-ethylhexyl phosphate), P204 (di(2-ethylhexyl) phosphate), TBP (tributyl phosphate), P350 (dimethylheptyl methylphosphonate), Cyanex 923 (linear trialkylphosphine oxide), Cyanex 272 (bis(2,4,4-trimethylpentyl)phosphonic acid), N235 (trioctyldecyl tertiary amine), DDPA (dicepoxyphosphonic acid), or DEHPA (dialkyl phosphate). Typical but non-limiting combinations include the combination of P507 and P204, the combination of TBP and P350, the combination of P350 and Cyanex 923, the combination of TBP and DEHPA, the combination of P507, P204, and Cyanex 923, or the combination of P507, Cyanex 272, DEHPA, and TBP.

[0030] In this invention, organophosphate exists in the organic phase as a dimer (H₂A₂). When the dimer dissociates into monomers, acidic ionization occurs at the interface, generating an extractable via ion exchange mechanism. The main extraction process is as follows:

[0031]

[0032] RE 3+ +3H2A2=RE(HA2)3+3H +

[0033] Preferably, the diluent comprises any one or a combination of at least two of benzene, chloroform, carbon tetrachloride, n-hexane, n-heptane, n-dodecane, n-butyl ether, kerosene, or ethyl acetate. Typical but non-limiting combinations include benzene and chloroform, carbon tetrachloride and n-hexane, n-dodecane and n-butyl ether, kerosene and ethyl acetate, and benzene, chloroform, and carbon tetrachloride. Alternatively, a combination of n-dodecane, n-butyl ether, kerosene, and ethyl acetate.

[0034] Preferably, the extraction ratio O / A is (1-50):(10-1), for example, it can be 1:10, 30:10, 50:10, 1:5, 30:5, 50:5, 1:1, 30:1 or 50:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably (1-30):(10-1).

[0035] Preferably, the extraction stages are 1-50, for example, stages 1, 5, 10, 20, 30, 40 or 50, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the extraction time is 0.3-2 hours, for example, 0.3 hours, 0.5 hours, 1 hour, 1.5 hours or 2 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the extraction temperature is 15-100℃, for example, it can be 15℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the method further includes: back-extracting the rare earth organic phase in step (2) with acid to obtain a rare earth solution and an extract, reusing the resulting extract in step (2) for extraction, and evaporating, concentrating, and cooling the rare earth solution to obtain a rare earth product.

[0039] As a preferred embodiment of the method provided by the present invention, the method includes the following steps:

[0040] (1) A rare earth iron mixed solution with pH < 7 was mixed with a quenching agent. Under light irradiation with a wavelength of 100-1000 nm and a power of 200-600 W, the Fe in the rare earth iron mixed solution was measured. 3+ A reduction reaction occurs, wherein the amount of quencher used is equal to the amount of Fe reduced. 3 +The required amount is 100-2000 times the theoretical amount; the reduction reaction temperature is 20-80℃; and the reduction reaction time is 0.5-2 hours. (Fe) 3+ Reduced to Fe 2+ A reduced solution is obtained;

[0041] (2) The reduced solution obtained in step (1) is extracted using an extraction solution. The extractant in the extraction solution is an organophosphorus extractant. The concentration of the extractant in the extraction solution is 0.01-90%. The extraction ratio O / A is (1-30):(10-1). The number of extraction stages is 1-50. The extraction temperature is 15-100℃. The extraction time is 0.3-2h. After the extraction is completed, a rare earth organic phase and an iron-rich raffinate are obtained.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The method provided by this invention reduces ferric ions to ferrous ions by controlling the valence state of ferric ions in rare earth solutions, thus solving the problem that ferric ions are easily extracted simultaneously when rare earth ions are extracted by extraction, and improving the separation effect of iron and rare earth elements. The reduction of ferric ions adopts a photo-reduction method, which is simple, has a good reduction effect, does not require the introduction of reducing agents, and the quenching agent is easy to remove, avoiding the introduction of difficult-to-separate impurities. Moreover, the extractant after the reaction can be recycled. Attached Figure Description

[0044] Figure 1 This is a process flow diagram of the method provided in Example 1;

[0045] Figure 2 This is a bar chart showing the elemental concentrations of the solution before and after extraction in Example 1;

[0046] Figure 3 This is a bar chart showing the elemental concentrations of the solution before and after extraction in Example 2.

[0047] Figure 4 This is a bar chart showing the elemental concentrations of the solution before and after extraction in Example 3. Detailed Implementation

[0048] 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.

[0049] Example 1

[0050] This embodiment provides a method such as Figure 1 The method shown utilizes photoreduction-assisted extraction to separate rare earth elements and iron.

[0051] The rare earth iron mixed solution used is a ytterbium iron mixed solution, in which Yb 3+The concentration was 1000 ppm, Fe 3+ The concentration of the rare earth element is 10 ppm, the pH of the solution is 2, and the concentration ratio of rare earth ions to iron ions is 100.

[0052] The method includes the following steps:

[0053] (1) Take 80 mL of rare earth iron mixed solution and add 0.42 mL of anhydrous ethanol as quencher. The purity of the anhydrous ethanol is 99%. The amount of quencher used is 500 times the theoretical amount. Use light with a wavelength range of 100-500 nm and a light power of 600 W to carry out the reduction reaction. The reaction temperature is 25℃ and the reaction time is 0.5 h to obtain the reduced solution.

[0054] (2) Take 25 mL of the reduction solution obtained in step (1) and add 5 mL of extraction solution, wherein the extractant is P507, the diluent is n-heptane, the volume fraction of the extractant is 5%, the ratio of O / A is 1:5, shake at room temperature (25℃) for 40 min to extract, and then separate the organic phase and the raffinate.

[0055] The concentrations of ytterbium and iron in the raffinate were 220.77 ppm and 8.24 ppm, respectively. The extraction rates of ytterbium and iron were calculated to be 77.7% and 19.2%, respectively. The separation coefficient β of ytterbium and iron was 14.6.

[0056] Example 2

[0057] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction.

[0058] The rare earth iron mixed solution used is an erbium iron mixed solution, wherein Er 3+ The concentration was 119 ppm, Fe 3+ The concentration of rare earth ions was 113 ppm, the pH of the solution was 2, and the concentration ratio of rare earth ions to iron ions was 1:1.

[0059] The method includes the following steps:

[0060] (1) Take 100 mL of rare earth iron mixed solution and add 2.03 mL of anhydrous ethanol as quencher. The purity of the anhydrous ethanol is 99%. The amount of quencher used is 2000 times the theoretical amount. Use light with a wavelength range of 100-500 nm and a light power of 300 W to carry out the reduction reaction. The reaction temperature is 25℃ and the reaction time is 0.5 h to obtain the reduced solution.

[0061] (2) Take 10 mL of the reduction solution obtained in step (1) and add 10 mL of extraction solution, wherein the extractant is P507, the diluent is n-heptane, the volume fraction of the extractant is 0.03%, the ratio of O / A is 1:1, shake at room temperature (25℃) for 20 min to extract, and then separate the organic phase and the raffinate.

[0062] The concentrations of erbium and iron in the raffinate were 6.3 ppm and 108.2 ppm, respectively. The extraction rates of erbium and iron were calculated to be 94.7% and 4.2%, respectively. The separation coefficient β of erbium and iron was 409.

[0063] Example 3

[0064] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction.

[0065] The rare earth iron mixed solution used was the same as that in Example 1, which was a ytterbium iron mixed solution.

[0066] The method includes the following steps:

[0067] (1) Take 100 mL of rare earth iron mixed solution and add 2.03 mL of anhydrous ethanol as quencher. The purity of the anhydrous ethanol is 99%. The amount of quencher used is 100 times the theoretical amount. Use light with a wavelength range of 100-500 nm and a light power of 200 W to carry out the reduction reaction. The reaction temperature is 80 °C and the reaction time is 0.5 h to obtain the reduction solution.

[0068] (2) Take 10 mL of the reduction solution obtained in step (1) and add 100 mL of extraction solution, wherein the extractant is P507, the diluent is n-heptane, the volume fraction of the extractant is 0.01%, the ratio of O / A is 10:1, shake at room temperature (25℃) for 20 min to extract, and then separate the organic phase and the raffinate.

[0069] The concentrations of ytterbium and iron in the raffinate were analyzed to be 521 ppm and 9 ppm, respectively. The extraction rates of ytterbium and iron were calculated to be 46.8% and 10.4%, respectively, and the separation coefficient β of ytterbium and iron was 7.9.

[0070] Example 4

[0071] This embodiment provides a method for separating rare earth elements and iron by photoreduction-assisted extraction. Compared with embodiment 1, in the control step (1), the amount of quenching agent is 1 times the theoretical amount, the light power is 1000W, and the rest are the same as in embodiment 1.

[0072] Example 5

[0073] This embodiment provides a method for separating rare earth elements and iron by photoreduction-assisted extraction. Compared with embodiment 1, in step (1), the amount of quenching agent is 1000 times the theoretical amount, the light power is 10W, and the rest are the same as in embodiment 1.

[0074] Example 6

[0075] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction. Compared with Example 1, the quenching agent anhydrous ethanol is replaced with an equal amount of dimethyl sulfoxide, and the rest is the same as in Example 1.

[0076] Example 7

[0077] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction. Compared with Example 1, the quenching agent anhydrous ethanol is replaced with an equal amount of acetylacetone, and the rest is the same as in Example 1.

[0078] Example 8

[0079] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction. Compared with Example 1, the quenching agent anhydrous ethanol is replaced with an equal amount of n-butanol, and all other aspects are the same as in Example 1.

[0080] Example 9

[0081] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction. Compared with Example 1, the quenching agent anhydrous ethanol is replaced with an equal amount of methanol, and all other aspects are the same as in Example 1.

[0082] Example 10

[0083] This embodiment provides a method for separating rare earth elements and iron using photoreduction-assisted extraction. Compared with Embodiment 1, the wavelength of the light used is 500-1000nm, and the rest is the same as in Embodiment 1.

[0084] Comparative Example 1

[0085] This comparative example provides a method for extracting and separating rare earth elements and iron. Compared with Example 1, step (1) is not subject to light irradiation, and the rest is the same as Example 1.

[0086] Comparative Example 2

[0087] This comparative example provides a method for extracting and separating rare earth elements and iron. Compared with Example 1, step (1) does not involve the addition of a quenching agent, while the rest is the same as in Example 1.

[0088] The concentrations of rare earth elements and iron in the reduction solution and the resulting raffinate in the examples and comparative examples were determined by ICP-OES. The elemental extraction rate was calculated, and the separation coefficient β between rare earth elements and iron was calculated.

[0089] The separation coefficient (β) is defined as the ratio of the distribution ratios (D) of the two elements, and is calculated using the following formula:

[0090] D RE =C org / C aq

[0091] D Fe =C' org / C' aq

[0092] β RE / Fe =D RE / D Fe

[0093] In the formula, C org C aq The concentrations (mol / L) of rare earth elements in the supported organic phase and the raffinate aqueous phase are respectively; C' org C' aq The values ​​represent the concentrations (mol / L) of Fe in the supported organic phase and the raffinate aqueous phase, respectively.

[0094] Figure 2 , Figure 3 and Figure 4 The bar charts show the elemental concentrations in the reduced solution and raffinate in Examples 1, 2, and 3, respectively. The calculation results for the examples and comparative examples are listed in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] As can be seen from Table 1, the photoreduction-assisted extraction separation method provided by this invention can effectively separate rare earth and iron ions in solution, especially for cases where the concentration ratio of rare earth ions to iron ions in solution is relatively high (RE). 3+ / Fe 3+ Even with concentrations of ≥100 ppm and lower iron ion concentrations (10-100 ppm), it still exhibits good separation performance.

[0099] In Examples 4 and 5, the amount of quenching agent or the light power was relatively low, resulting in incomplete reduction of ferric ions in the solution, which in turn led to the extraction of more ferric ions and a significant increase in the iron extraction rate.

[0100] In Example 10, the light reduction effect was reduced due to the use of longer wavelength illumination conditions.

[0101] In Comparative Examples 1 and 2, no light or quenching agent was introduced during the reduction process, making it difficult to completely reduce ferric ions. Competition for extraction still occurred during the extraction process, resulting in a high iron extraction rate and making effective separation difficult.

[0102] In summary, the method provided by this invention reduces ferric ions to ferrous ions by controlling the valence state of ferric ions in rare earth solutions, thus solving the problem of simultaneous extraction of ferric ions when using extraction to extract rare earth ions, and improving the separation effect of iron and rare earth elements. The reduction of ferric ions adopts a photo-reduction method, which is simple, has a good reduction effect, does not require the introduction of a reducing agent, and the quenching agent is easy to remove, avoiding the introduction of difficult-to-separate impurities. Furthermore, the extractant after the reaction can be recycled.

[0103] The applicant declares that 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 separating rare earth elements and iron using photoreduction-assisted extraction, characterized in that, The method includes the following steps: (1) Using light and quenching agents, Fe in the rare earth iron mixed solution is removed. 3+ A reduction reaction occurs, yielding a reduced solution; (2) The reduced solution obtained in step (1) is extracted with the extraction liquid to obtain a rare earth organic phase and an iron-rich raffinate.

2. The method according to claim 1, characterized in that, The rare earth iron mixed solution includes acid leaching solution of rare earth oxides and / or ion-type rare earth ore leaching solution. Preferably, in the rare earth iron mixed solution, the mass concentration ratio of rare earth ions to iron ions is RE 3+ / Fe 3+ The ratio is 1:1 to 10000:1; Preferably, the anions in the rare earth iron mixed solution include Cl-. - and / or NO3 - ; Preferably, the pH of the rare earth iron mixed solution is <7.

3. The method according to claim 1 or 2, characterized in that, The wavelength of the illumination is 100-1000 nm; Preferably, the power of the illumination is 10-1000W, and more preferably 200-600W.

4. The method according to any one of claims 1-3, characterized in that, The quenching agent includes any one or a combination of at least two of ethanol, isopropanol, tert-butanol, methanol, n-heptanol, n-octanol or glycerol, preferably any one or a combination of at least two of methanol, tert-butanol or ethanol. Preferably, the amount of quenching agent used is reduced Fe. 3+ The required amount is 1-5000 times the theoretical amount, preferably 100-2000 times.

5. The method according to any one of claims 1-4, characterized in that, The reduction reaction takes 0.5-5 hours, preferably 0.5-2 hours. Preferably, the temperature of the reduction reaction is 20-80℃.

6. The method according to any one of claims 1-5, characterized in that, The extract includes an extractant and a diluent; Preferably, the concentration of the extractant in the extract solution is 0.01-100%, more preferably 0.01-90%.

7. The method according to claim 6, characterized in that, The extractant includes an organophosphorus extractant; Preferably, the organophosphorus extractant comprises any one or a combination of at least two of P507, P204, TBP, P350, P503, Cyanex923, Cyanex272, N235, DDPA, or DEHPA; Preferably, the diluent comprises any one or a combination of at least two of the following: benzene, chloroform, carbon tetrachloride, n-hexane, n-heptane, n-dodecane, n-butyl ether, kerosene, or ethyl acetate.

8. The method according to any one of claims 1-7, characterized in that, The extraction ratio O / A is (1-50):(10-1), preferably (1-30):(10-1); Preferably, the extraction stages are 1-50.

9. The method according to any one of claims 1-8, characterized in that, The extraction time is 0.3-2 hours; Preferably, the extraction temperature is 15-100℃.

10. The method according to any one of claims 1-9, characterized in that, The method includes the following steps: (1) A rare earth iron mixed solution with pH < 7 was mixed with a quenching agent. Under light irradiation with a wavelength of 100-1000 nm and a power of 200-600 W, the Fe in the rare earth iron mixed solution was measured. 3+ A reduction reaction occurs, wherein the amount of quencher used is equal to the amount of Fe reduced. 3+ The required amount is 100-2000 times the theoretical amount; the reduction reaction temperature is 20-80℃; and the reduction reaction time is 0.5-2 hours. (Fe) 3+ Reduced to Fe 2+ A reduced solution is obtained; (2) The reduced solution obtained in step (1) is extracted using an extraction solution. The extractant in the extraction solution is an organophosphorus extractant. The concentration of the extractant in the extraction solution is 0.01-90%. The extraction ratio O / A is (1-30):(10-1). The number of extraction stages is 1-50. The extraction temperature is 15-100℃. The extraction time is 0.3-2h. After the extraction is completed, a rare earth organic phase and an iron-rich raffinate are obtained.

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