Defluorination recovery method of rare earth feed liquid

Abstract

The invention provides a rare earth feed liquid defluorination recovery method, which comprises: (1) adjusting the pH value of a rare earth feed liquid by using an alkaline material, and mixing the pH-adjusted rare earth feed liquid with a rare earth compound to carry out a one-step reaction; and (2) carrying out one-step solid-liquid separation treatment on the material obtained by the one-step reaction in the step (1) to obtain impurity-removed slag and rare earth purified feed liquid, mixing the obtained impurity-removed slag with an alkaline solution to carry out two-step reaction, and carrying out two-step solid-liquid separation treatment on the material obtained by the two-step reaction to obtain a rare earth enriched product and fluorine-containing waste liquid. By means of the defluorination recovery method, fluorine ions in the rare earth feed liquid can be removed, meanwhile, obtained impurity removal residues can be recycled, and resources are saved.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth production and relates to a defluorination recovery method for rare earth liquid. Background Art

[0002] Among the main rare earth raw materials, ion-adsorbing rare earth minerals, rare earths are adsorbed in ionic form on minerals such as kaolinite and mica, and also adsorb aluminum, iron, fluorine, calcium and other substances. In the process of rare earth extraction and separation, the acid dissolution-precipitation process is currently widely used to treat rare earth concentrates. In addition to rare earths, impurities such as fluorine also enter the rare earth acid leaching solution. In the production process of rare earth extraction and separation, the fluorine ions in the rare earth solution will form chelates with other ions at a certain acidity and concentration, or form insoluble precipitates and enter the extraction organic phase, thereby affecting the rare earth extraction and separation effect. In addition, the fluorine element will also enter the rare earth oxide product along with the rare earth production process, ultimately affecting the quality of the product. Therefore, the development and establishment of a new method for deep defluorination of rare earth feed liquid to obtain a rare earth purified liquid with a low fluorine content is an important way to improve the quality of rare earth products.

[0003] CN115927884A discloses a method for removing fluorine from a rare earth ore leachate, comprising the following steps: adding solution A to a fluorine-containing rare earth ore leachate, stirring and adjusting the pH value of the fluorine-containing ion-type rare earth ore leachate, obtaining solution B after clarification and solid-liquid separation, adding solution C to solution B, obtaining a precipitate after clarification and solid-liquid separation, adding solution D to the precipitate, stirring and leaching, performing filter pressing and solid-liquid separation, and obtaining a rare earth ore with a low fluorine content.

[0004] CN117904436A discloses a method for removing fluorine from a rare earth ore leachate, which comprises the following steps: S1, adding ammonium bicarbonate to the rare earth ore leachate, and separating the solid and liquid after clarifying to obtain a filtrate A and a filter residue A; S2, adding ammonium bicarbonate to the filtrate A, and separating the solid and liquid to obtain a filtrate B and a filter residue B; S3, adding concentrated sulfuric acid to the filter residue A, and adding the filtrate B in step S2, and separating the solid and liquid to obtain a filtrate C and a filter residue C; S4, adding oxalic acid solution to the filtrate C, stirring and reacting, and filtering after clarifying to obtain a filtrate D and a filter residue D; S5, adding calcium salt or magnesium salt to the filtrate D, and separating the solid and liquid to obtain a CaF2 or MgF2 filter residue and a filtrate E; S6, mixing the filtrate B and the filtrate E, and recycling them for continuous use in leaching rare earth ore, and the filter residue B and the filter residue D are the rare earth products after defluorination.

[0005] However, the current defluorination and recovery methods for rare earth liquid still have the disadvantages of poor defluorination effect, complicated process, and difficulty in reusing the defluorination agent. Summary of the invention

[0006] The object of the present invention is to provide a defluorination recovery method for rare earth liquid. The defluorination recovery method of the present invention can not only remove fluorine ions in the rare earth liquid, but also recycle the obtained impurity removal residue to save resources.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for defluorination recovery of a rare earth liquid, the defluorination recovery method comprising the following steps:

[0009] (1) After adjusting the pH of the rare earth solution using an alkaline material, the rare earth solution after the pH adjustment is mixed with a rare earth compound to perform a one-step reaction;

[0010] (2) subjecting the material obtained in the one-step reaction of step (1) to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purified liquid, mixing the obtained impurity-removing slag with an alkaline solution to a two-step reaction, and subjecting the material obtained in the two-step reaction to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

[0011] The defluorination and recovery method of the rare earth liquid of the present invention introduces rare earth compounds into the acidic rare earth liquid to form precipitation with fluoride ions and defluorinate by synergistic adsorption, so that the fluoride ions in the rare earth liquid can be deeply removed to below 50 ppm. The obtained impurity-removing slag can effectively separate fluorine and rare earth after reacting with an alkaline solution. At the same time, the obtained rare earth enriched product can be reused, thereby realizing the recovery and reuse of rare earth.

[0012] Preferably, the rare earth solution in step (1) comprises rare earth compounds, aluminum ions and fluoride ions.

[0013] Preferably, the mass concentration of the rare earth compound in the rare earth solution in step (1) is 150 g / L to 200 g / L, for example, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L or 200 g / L, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] Preferably, the rare earth compound includes any one or a combination of at least two of oxides, hydroxides or carbonates containing rare earth elements. Typical but non-limiting combinations include a combination of oxides and hydroxides containing rare earth elements, a combination of oxides and carbonates containing rare earth elements, or a combination of hydroxides and hydroxides containing rare earth elements, etc.

[0015] Preferably, the rare earth element includes any one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium or yttrium, or a combination of at least two of them. Typical but non-limiting combinations include a combination of lanthanum and cerium, a combination of cerium and scandium, or a combination of cerium and praseodymium, etc.

[0016] Preferably, the mass concentration of aluminum ions in the rare earth solution in step (1) is 4 g / L to 5 g / L, for example 4 g / L, 4.2 g / L, 4.5 g / L, 4.8 g / L or 5 g / L, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the mass concentration of fluoride ions in the rare earth solution in step (1) is 1 g / L to 1.5 g / L, for example, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L or 1.5 g / L, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the pH of the rare earth solution in step (1) is 2 to 3, for example, 2, 2.2, 2.5, 2.8 or 3, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the alkaline material in step (1) comprises any one of aqueous ammonia, sodium aluminate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or rare earth concentrate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of aqueous ammonia and sodium aluminate, a combination of sodium carbonate and potassium carbonate, or a combination of potassium carbonate and sodium bicarbonate.

[0020] Preferably, the pH of the rare earth solution is adjusted to 3.5-5.5 in step (1), for example, 3.5, 4, 4.5, 5 or 5.5, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0021] Preferably, the rare earth compound in step (1) comprises any one of rare earth oxides, rare earth hydroxides or rare earth carbonates, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of rare earth oxides and rare earth carbonates, a combination of rare earth oxides and rare earth hydroxides, or a combination of rare earth hydroxides and rare earth carbonates, etc.

[0022] Preferably, the mass volume ratio of the rare earth compound to the rare earth liquid in step (1) is 5 g / L to 50 g / L, for example: 5 g / L, 10 g / L, 20 g / L, 30 g / L or 50 g / L, not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 20 g / L to 30 g / L.

[0023] Preferably, stirring is performed during the one-step reaction in step (1).

[0024] Preferably, the stirring speed is 10 rpm to 500 rpm, for example, 10 rpm, 50 rpm, 100 rpm, 200 rpm or 500 rpm, etc., not limited to the listed values, other values ​​not listed in the numerical range are also applicable, preferably 100 rpm to 200 rpm.

[0025] Preferably, the temperature of the one-step reaction in step (1) is 50°C to 95°C, for example, 50°C, 55°C, 60°C, 80°C or 95°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 60°C to 95°C.

[0026] Preferably, the reaction time of step (1) is 0.5 h to 10 h, for example, 0.5 h, 1 h, 5 h, 8 h or 10 h, etc., not limited to the listed values, other values ​​not listed in the numerical range are also applicable, preferably 1 h to 6 h.

[0027] Preferably, the alkaline solution in step (2) comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0028] Preferably, the mass concentration of the alkaline solution in step (2) is 5 g / L to 50 g / L, for example, 5 g / L, 10 g / L, 20 g / L, 30 g / L or 50 g / L, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 10 g / L to 30 g / L.

[0029] Preferably, stirring is performed during the two-step reaction in step (2).

[0030] Preferably, the stirring speed is 10 rpm to 500 rpm, for example, 10 rpm, 50 rpm, 100 rpm, 200 rpm or 500 rpm, etc., not limited to the listed values, other values ​​not listed in the numerical range are also applicable, preferably 100 rpm to 200 rpm.

[0031] Preferably, the temperature of the two-step reaction in step (2) is 50°C to 95°C, for example, 50°C, 55°C, 60°C, 80°C or 95°C, etc., preferably 60°C to 95°C.

[0032] Preferably, the time of the two-step reaction in step (2) is 0.5 h to 10 h, for example, 0.5 h, 1 h, 5 h, 8 h or 10 h, etc., not limited to the listed values, other values ​​not listed in the numerical range are also applicable, preferably 1 h to 6 h.

[0033] As a preferred embodiment of the present invention, the defluorination recovery method comprises the following steps:

[0034] (1) After adjusting the pH of the rare earth solution to 4-5 using an alkaline material, the rare earth compound is mixed with the rare earth solution after the pH is adjusted at a mass volume ratio of 20 g / L-30 g / L, and a one-step reaction is carried out at 60° C.-95° C. and at a stirring speed of 100 rpm-200 rpm for 1 h-6 h.

[0035] (2) subjecting the material obtained by the one-step reaction in step (1) to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purified liquid, mixing the obtained impurity-removing slag with an alkaline solution having a mass concentration of 10 g / L to 30 g / L, and carrying out a two-step reaction at 60° C. to 95° C. and at a stirring speed of 100 rpm to 200 rpm for 1 h to 6 h, subjecting the material obtained by the two-step reaction to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The defluorination recovery method of the present invention can not only remove fluorine from the rare earth liquid, but also recycle the obtained impurity-removing slag, thus saving resources.

[0038] (2) The defluorination recovery method of the present invention not only has mild conditions, does not require high temperature and pressure, and will not form harmful substances with rare earths, but also has the advantages of simple process and low production cost.

[0039] (3) The present invention introduces rare earth compounds to form precipitation with fluorine and defluorinates by synergistic adsorption, which can remove fluoride ions in the rare earth liquid to below 50 mg / L, meeting the requirements of subsequent extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a process flow chart of the defluorination recovery method of rare earth liquid provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0042] In the rare earth solution used in the embodiments of the present invention and the comparative example, the mass concentration of the rare earth compound is 200 g / L, the mass concentration of the F ion is 1.2 g / L, and the mass concentration of the aluminum ion is 5.0 g / L, wherein the rare earth compound includes lanthanum oxide, cerium oxide, lanthanum hydroxide, cerium hydroxide, lanthanum carbonate, cerium carbonate, etc.

[0043] Example 1

[0044] This embodiment provides a defluorination recovery method for rare earth liquid. The process flow chart of the defluorination recovery method is as follows: Figure 1 As shown, the defluorination recovery method comprises the following steps:

[0045] (1) After the pH of the rare earth solution is adjusted to 4.5 using ammonia water, a rare earth hydroxide having the same rare earth element as that in the rare earth solution is mixed with the rare earth solution after the pH is adjusted at a mass volume ratio of 20 g / L, and a one-step reaction is carried out at 90° C. and at a stirring speed of 200 rpm for 6 hours.

[0046] (2) The material obtained in the one-step reaction of step (1) is subjected to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purification liquid, 5 g of the obtained impurity-removing slag is mixed with a sodium hydroxide solution with a mass concentration of 20 g / L, and a two-step reaction is carried out at 80° C. and at a stirring speed of 200 rpm for 5 hours. The material obtained in the two-step reaction is subjected to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

[0047] Example 2

[0048] This embodiment provides a defluorination recovery method for rare earth liquid. The process flow chart of the defluorination recovery method is as follows: Figure 1 As shown, the defluorination recovery method comprises the following steps:

[0049] (1) After the pH of the rare earth solution is adjusted to 4 using ammonia water, a rare earth hydroxide having the same rare earth element as that in the rare earth solution is mixed with the rare earth solution after the pH is adjusted at a mass volume ratio of 20 g / L, and a one-step reaction is carried out at 690° C. and at a stirring speed of 150 rpm for 6 hours.

[0050] (2) The material obtained in the one-step reaction of step (1) is subjected to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purification liquid, 5 g of the obtained impurity-removing slag is mixed with a sodium hydroxide solution with a mass concentration of 10 g / L, and a two-step reaction is carried out at 60° C. and 150 rpm with stirring for 6 hours, and the material obtained in the two-step reaction is subjected to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

[0051] Example 3

[0052] This embodiment provides a defluorination recovery method for rare earth liquid. The process flow chart of the defluorination recovery method is as follows: Figure 1 As shown, the defluorination recovery method comprises the following steps:

[0053] (1) After the pH of the rare earth solution is adjusted to 5 using ammonia water, a rare earth hydroxide having the same rare earth element as that in the rare earth solution is mixed with the rare earth solution after the pH is adjusted at a mass volume ratio of 30 g / L, and the mixture is stirred at 95° C. and 100 rpm for a one-step reaction for 16 hours.

[0054] (2) The material obtained in the one-step reaction of step (1) is subjected to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purification liquid, 5 g of the obtained impurity-removing slag is mixed with a sodium hydroxide solution with a mass concentration of 30 g / L, and a two-step reaction is carried out at 88° C. and 200 rpm with stirring for 3 h, and the material obtained in the two-step reaction is subjected to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

[0055] Example 4

[0056] The only difference between this embodiment and embodiment 3 is that the pH in step (1) is adjusted to 3.5, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0057] Example 5

[0058] The only difference between this embodiment and embodiment 3 is that in step (1), the pH is adjusted to 5.5, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0059] Example 6

[0060] The only difference between this embodiment and embodiment 3 is that the mass volume ratio in step (1) is 5 g / L, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0061] Example 7

[0062] The only difference between this embodiment and embodiment 3 is that the mass-to-volume ratio in step (1) is 50 g / L, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0063] Example 8

[0064] The only difference between this embodiment and embodiment 3 is that the reaction temperature in step (1) is 50° C., and the other conditions and parameters are exactly the same as those in embodiment 3.

[0065] Example 9

[0066] The only difference between this embodiment and embodiment 3 is that the reaction temperature in step (1) is 100° C., and the other conditions and parameters are exactly the same as those in embodiment 3.

[0067] Example 10

[0068] The only difference between this embodiment and embodiment 3 is that the stirring speed of the reaction in step (1) is 10 rpm, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0069] Embodiment 11

[0070] The only difference between this embodiment and embodiment 3 is that the stirring speed of the reaction in step (1) is 500 rpm, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0071] Example 12

[0072] The only difference between this embodiment and embodiment 3 is that the mass concentration of the sodium hydroxide solution in step (2) is 5 g / L, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0073] Embodiment 13

[0074] The only difference between this embodiment and embodiment 3 is that the mass concentration of the sodium hydroxide solution in step (2) is 50 g / L, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0075] Embodiment 14

[0076] The only difference between this embodiment and embodiment 3 is that the reaction temperature in step (2) is 50° C., and the other conditions and parameters are exactly the same as those in embodiment 3.

[0077] Embodiment 15

[0078] The only difference between this embodiment and embodiment 3 is that the reaction temperature in step (2) is 100° C., and the other conditions and parameters are exactly the same as those in embodiment 3.

[0079] Example 16

[0080] The only difference between this embodiment and embodiment 3 is that the stirring speed of the reaction in step (2) is 10 rpm, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0081] Embodiment 17

[0082] The only difference between this embodiment and embodiment 3 is that the stirring speed of the reaction in step (1) is 500 rpm, and the other conditions and parameters are exactly the same as those in embodiment 3.

[0083] Comparative Example 1

[0084] The only difference between this comparative example and Example 3 is that the pH is not adjusted in step (1), and the other conditions and parameters are exactly the same as those in Example 3.

[0085] Performance Test:

[0086] The fluorine content of the rare earth purification liquid obtained in the embodiment and the comparative example was detected, and the fluorine dissolution rate was calculated based on the obtained fluorine-containing waste liquid. The calculation method is as follows: first, a certain amount of W0 (g) of impurity removal slag was added with acid to completely dissolve, and the quantity was V0 (L). The fluorine concentration was tested by ICP as C0 (g / L), and the total fluorine content in the impurity removal slag was recorded as: f = C0*V0 / W0; secondly, a certain amount of W (g) of impurity removal slag was subjected to an alkali dissolution experiment, the volume was recorded as V (L), and the fluorine concentration of the ICP test solution was C (g / L), and the fluorine dissolution rate was recorded as: C*V / W*f. The test results are shown in Table 1:

[0087] Table 1

[0088]

[0089]

[0090] As can be seen from Table 1, from Examples 1-17, the defluorination recovery method of the rare earth feed solution of the present invention can obtain a F ion content in the rare earth purification feed solution of less than 136.13 ppm, and a F ion dissolution rate of more than 40.2%. The defluorination effect of the rare earth feed solution is closely related to the solution pH, rare earth compound concentration, reaction temperature, time, and rotation speed. By adjusting the above factors, the F ion content in the rare earth purification feed solution can reach less than 27.86 ppm, and the F ion dissolution rate can reach more than 86.5%.

[0091] By comparing Example 3 with Examples 4-5, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, adjusting the pH of the rare earth liquid in step (1) will affect the recovery effect. When the pH of the rare earth liquid is adjusted to 4-5, the defluorination effect is better. If the pH is too low, the added rare earth compound will dissolve and the defluorination effect will deteriorate. If the pH is too high, the defluorination effect cannot be further improved.

[0092] By comparing Example 3 with Examples 6-7, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, the amount of rare earth hydroxide added in step (1) will affect the recovery effect. When the mass volume ratio of rare earth hydroxide to rare earth liquid is controlled at 10-30 g / L, the defluorination effect is better. If the amount of rare earth hydroxide added is too low, saturation occurs too early and deep defluorination is difficult. If the amount of rare earth hydroxide added is too high, the defluorination effect cannot be further improved.

[0093] By comparing Example 3 with Examples 8-9, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, the temperature of the reaction in step (1) will affect the recovery effect. When the temperature of the reaction in step (1) is controlled at 60-95°C, the defluorination effect is better. If the temperature of the reaction in step (1) is too low, the reaction rate will slow down and the defluorination effect will deteriorate. If the temperature of the reaction in step (1) is too high, the defluorination effect cannot be further improved.

[0094] By comparing Example 3 with Examples 10-11, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, the stirring speed of the reaction in step (1) will affect the recovery effect. When the stirring speed of the reaction in step (1) is controlled at 100-200 rpm, the defluorination effect is better. If the stirring speed of the reaction in step (1) is too low, the rare earth compound will have poor dispersion and form inclusions, thereby hindering defluorination. If the temperature stirring speed of the reaction in step (1) is too high, the defluorination effect cannot be further improved.

[0095] By comparing Example 3 with Examples 12-13, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, the mass concentration of the sodium hydroxide solution in step (2) will affect the recovery effect. When the mass concentration of the sodium hydroxide solution is controlled at 10-30 g / L, the defluorination effect is better. If the mass concentration of the sodium hydroxide solution is too low, the exchange capacity between hydroxide ions and fluoride ions is weak, thereby reducing the dissolution rate of fluoride ions. If the mass concentration of the sodium hydroxide solution is too high, the defluorination effect cannot be further improved.

[0096] By comparing Example 3 with Examples 14-15, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, the temperature of the reaction in step (2) will affect the recovery effect. When the temperature of the reaction in step (2) is controlled at 60-95°C, the defluorination effect is better. If the temperature of the reaction in step (2) is too low, the reaction rate will be too slow and the dissolution rate of fluoride ions will be reduced. If the temperature of the reaction in step (2) is too high, the defluorination effect cannot be further improved.

[0097] By comparing Example 3 with Examples 16-17, it can be seen that in the defluorination recovery method of the rare earth liquid of the present invention, the stirring speed of the reaction in step (2) will affect the recovery effect. When the stirring speed of the reaction in step (2) is controlled at 100-200 rpm, the defluorination effect is better. If the stirring speed of the reaction in step (2) is too low, the dispersion of the impurity removal residue is poor and the mixing with the alkali solution is not thorough, resulting in a decrease in the dissolution rate of fluoride ions. If the temperature stirring speed of the reaction in step (2) is too high, the defluorination effect cannot be further improved.

[0098] From the comparison between Example 3 and Comparative Example 1, it can be seen that the pH needs to be pre-adjusted before the reaction, otherwise the defluorination effect will be poor.

[0099] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for recovering rare earth liquid by defluorination, characterized in that: The defluorination recovery method comprises the following steps: (1) After adjusting the pH of the rare earth solution using an alkaline material, the rare earth solution after the pH adjustment is mixed with a rare earth compound to perform a one-step reaction; (2) subjecting the material obtained in the one-step reaction of step (1) to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purified liquid, mixing the obtained impurity-removing slag with an alkaline solution to a two-step reaction, and subjecting the material obtained in the two-step reaction to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

2. The defluorination recovery method according to claim 1, characterized in that: The rare earth liquid in step (1) comprises rare earth compounds, aluminum ions and fluoride ions; Preferably, the rare earth compound comprises any one or a combination of at least two of oxides, hydroxides or carbonates containing rare earth elements; Preferably, the rare earth element comprises any one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium or yttrium, or a combination of at least two thereof; Preferably, the mass concentration of the rare earth compound in the rare earth solution in step (1) is 150 g / L to 200 g / L; Preferably, the mass concentration of aluminum ions in the rare earth solution in step (1) is 4 g / L to 5 g / L; Preferably, the mass concentration of fluoride ions in the rare earth solution in step (1) is 1 g / L to 1.5 g / L; Preferably, the pH of the rare earth solution in step (1) is 2-3.

3. The defluorination recovery method according to claim 1 or 2, characterized in that: The alkaline material in step (1) includes any one of ammonia water, sodium aluminate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or rare earth concentrate, or a combination of at least two thereof.

4. The defluorination recovery method according to any one of claims 1 to 3, characterized in that: In step (1), the pH of the rare earth solution is adjusted to 3.5 to 5.

5.

5. The defluorination recovery method according to any one of claims 1 to 4, characterized in that: The rare earth compound in step (1) includes any one of rare earth oxides, rare earth hydroxides or rare earth carbonates, or a combination of at least two of them.

6. The defluorination recovery method according to any one of claims 1 to 5, characterized in that: The mass volume ratio of the rare earth compound to the rare earth liquid in step (1) is 5 g / L to 50 g / L, preferably 20 g / L to 30 g / L.

7. The defluorination recovery method according to any one of claims 1 to 6, characterized in that: Stirring during the one-step reaction of step (1); Preferably, the stirring speed is 10 rpm to 500 rpm, preferably 100 rpm to 200 rpm; Preferably, the temperature of the one-step reaction in step (1) is 50°C to 95°C, preferably 60°C to 95°C; Preferably, the one-step reaction time in step (1) is 0.5 h to 10 h, preferably 1 h to 6 h.

8. The defluorination recovery method according to any one of claims 1 to 7, characterized in that: The alkaline solution in step (2) comprises sodium hydroxide solution and / or potassium hydroxide solution; Preferably, the mass concentration of the alkaline solution in step (2) is 5 g / L to 50 g / L, preferably 10 g / L to 30 g / L.

9. The defluorination recovery method according to any one of claims 1 to 8, characterized in that: Stirring during the two-step reaction of step (2); Preferably, the stirring speed is 10 rpm to 500 rpm, preferably 100 rpm to 200 rpm; Preferably, the temperature of the second step reaction in step (2) is 50°C to 95°C, preferably 60°C to 95°C; Preferably, the time of the two-step reaction in step (2) is 0.5 h to 10 h, preferably 1 h to 6 h.

10. The defluorination recovery method according to any one of claims 1 to 9, characterized in that: The defluorination recovery method comprises the following steps: (1) After adjusting the pH of the rare earth solution to 4-5 using an alkaline material, the rare earth compound and the rare earth solution after the pH adjustment are mixed at a mass volume ratio of 20 g / L-30 g / L, and stirred at 60° C.-95° C. at a speed of 100 rpm-200 rpm for a one-step reaction for 1 h-6 h; (2) subjecting the material obtained by the one-step reaction in step (1) to a one-step solid-liquid separation treatment to obtain impurity-removing slag and rare earth purified liquid, mixing the obtained impurity-removing slag with an alkaline solution having a mass concentration of 10 g / L to 30 g / L, and carrying out a two-step reaction at 60° C. to 95° C. and at a stirring speed of 100 rpm to 200 rpm for 1 h to 6 h, subjecting the material obtained by the two-step reaction to a two-step solid-liquid separation treatment to obtain a rare earth enriched product and a fluorine-containing waste liquid.

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