A method for preparing rare earth feed liquid with low impurities using cerium-based materials

Abstract

The present invention relates to a method for preparing a rare earth feed liquid with low impurities using a cerium-based material, comprising the following steps: adding a certain proportion of a cerium-based material and a reducing agent to a rare earth feed liquid containing impurities through an oxidation-reduction process, where a redox reaction occurs between cerium dioxide in the cerium-based material and the reducing agent, and a part of cerium is dissolved out; precipitating common non-rare earth impurities such as aluminum, iron, uranium, thorium, and fluorine in the rare earth feed liquid to form impurity precipitates in a reaction system with a relatively low pH value through a process of precipitating impurities; forming an adsorbent material with a large specific surface area by the cerium-based material at the end point of impurity precipitation in terms of pH value through a process of adsorbing impurities, and effectively adsorbing the impurity precipitates in the liquid phase; separating the rare earth feed liquid and the solid that has adsorbed impurities by a simple method such as suction filtration or pressure filtration through a solid-liquid separation process to obtain a rare earth feed liquid with low impurities. The method provided by the present invention realizes the efficient separation of rare earths from impurities such as aluminum, iron, uranium, thorium, and fluorine, which is beneficial to improving the quality of rare earth separation products.

Description

Technical Field

[0001] The present invention belongs to the technical field of rare earth metallurgy, and particularly relates to a method for preparing rare earth feed liquid with low impurities by using cerium-based materials. Background Art

[0002] The mass percentage content of impurities such as aluminum and iron in ion-adsorption type rare earth ores is 0.5%-10%. During the separation and production process, the concentrate is dissolved by adding hydrochloric acid to obtain a rare earth feed liquid. The feed liquid is separated by extraction to obtain a chloride solution of one or several rare earths, and finally rare earth oxides are obtained through precipitation and calcination. The impurity aluminum element has a high proportion in the original ore and is dissolved with the rare earths during the acid dissolution process; the dissolved aluminum is easily enriched in the extractant, reducing the separation and treatment ability of the extractant; further, due to the change of the pH value during the extraction process, the formed colloidal aluminum hydroxide is easy to form a three-phase substance, affecting the progress of the separation process. Taking the feed liquid obtained from the acid dissolution workshop of a southern rare earth separation enterprise as an example, the concentration of the dissolved rare earth feed liquid is 1.51 mol / L, in which the impurity Al 2 O 3 is 3624 mg / L, and Al 2 O 3 / REO = 1.42%; other impurities: F 1540 mg / L, Fe 2 O 3 is 30 mg / L, U is 210 mg / L, Th is 36 mg / L, and Cr is 0.35 mg / L. Impurities such as aluminum are enriched to varying degrees, seriously affecting the quality of rare earth products. With the development of technology, the research and development and application of high-end materials require a large number of high-purity rare earth products.

[0003] At the same time, rare earths include 17 elements such as lanthanum, cerium, praseodymium, neodymium, terbium, dysprosium, and yttrium. The distribution and uses of each element are different. The total distribution of the high-abundance elements lanthanum, cerium, and yttrium is about 50%, but the application range is limited, resulting in the difficulty of achieving balanced utilization of rare earth elements and affecting the exertion of the value of rare earth resources. Therefore, there is an urgent need to develop technologies for removing impurities such as aluminum to prepare rare earth feed liquid with low impurities for industrial production and to promote the balanced application of high-abundance rare earths.

[0004] Currently, most production enterprises mainly use extraction method, precipitation method, activation-dissolution method to remove impurities such as aluminum to prepare rare earth feed liquid with low impurities.

[0005] In the existing separation method for removing aluminum from rare earth liquid by extraction, cyclopentane acid is used as an extractant. This process has the advantages of low production cost, good aluminum removal effect, and small loss of rare earth elements. Chinese patents CN103773955 and CN101979680 both use cyclopentane acid-alcohol-kerosene system to obtain rare earth liquid with relatively low impurity aluminum content through multi-stage saponification, extraction, washing, and stripping. The process is relatively stable. The current problems mainly include aging of the organic phase, reduced process efficiency caused by esterification reaction between cyclopentane acid and alcohol, and difficulty in phase separation caused by aluminum hydrolysis.

[0006] Precipitation aluminum removal mainly includes alkaline precipitation and acid precipitation. Chinese patent CN 110451539 uses alkaline solutions such as ammonium bicarbonate to adjust the pH value of the feed solution, and preferentially precipitates aluminum hydroxide. After solid-liquid separation, rare earth feed solution is obtained. The higher the aluminum hydroxide precipitation rate of this method, the greater the rare earth co-precipitation rate. The obtained neutralization and aluminum removal slag still needs to be treated with strong alkali and filtered multiple times, and the reaction process is relatively long. Chinese patents CN103194627 and CN116179876 use oxalic acid precipitation to precipitate rare earths. Impurities such as aluminum and iron are complexed with oxalic acid and remain in the precipitation mother liquor to achieve separation of impurities and rare earths. When there is more aluminum and iron in the oxalic acid precipitation method, the cost increases significantly.

[0007] Chinese patent CN113046578 proposes to remove aluminum from the upstream, that is, rare earth oxide concentrate, and prepare low-impurity rare earth liquid by activation-dissolution method. This process has the advantages of high efficiency, short process, and ideal removal of impurities such as aluminum. It has been promoted and applied by many rare earth separation enterprises in southern mines in my country. However, this method has a certain scope of application, and is currently mainly applicable to raw materials containing rare earth oxides. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a low-impurity rare earth liquid using a cerium-based material. The method is efficient, short-process, low-cost, has a wide range of applications, and is suitable for large-scale industrial production. The prepared rare earth liquid has lower contents of common non-rare earth impurities such as aluminum, iron, uranium, thorium, and fluorine, especially lower impurity aluminum content; the method overcomes the problems of long process, high cost, and raw material restrictions in the existing rare earth liquid aluminum removal process.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is: a method for preparing a low-impurity rare earth liquid using a cerium-based material, the method comprising the following steps:

[0010] S1. Redox: adding cerium-based materials and reducing agents to the rare earth liquid containing impurities to carry out redox reaction;

[0011] S2. Precipitating impurities: adjusting the pH value of the reaction system to precipitate impurities through precipitation reaction;

[0012] S3. Adsorb impurities: Maintain the pH value at the end point of the precipitation reaction and continue the reaction to complete the adsorption of impurity precipitation.

[0013] S4. Solid-liquid separation: Prepare the low-impurity rare earth feed liquid by performing solid-liquid separation on the rare earth feed liquid and the solid that has adsorbed impurities.

[0014] Furthermore, the rare earth feed liquid containing impurities is a hydrochloric acid and / or nitric acid rare earth solution, and the impurities in the rare earth feed liquid containing impurities include one or more of aluminum, iron, fluorine, uranium, and thorium.

[0015] Furthermore, in the rare earth feed liquid containing impurities, the concentration of rare earth elements is 0.1 - 2.5 mol / L; the pH value of the rare earth feed liquid containing impurities is < 5.5.

[0016] Furthermore, the cerium-based material is selected from one or more of cerium dioxide, cerium hydroxide, cerium dioxide-non-cerium rare earth composite material, cerium hydroxide-non-cerium rare earth composite material, cerium dioxide-non-rare earth metal composite material, cerium hydroxide-non-rare earth metal composite material, slag containing cerium dioxide, and slag containing cerium hydroxide.

[0017] Furthermore, the reducing agent includes one or more of citric acid, thiourea, urea, hydroxylamine hydrochloride, hydrogen peroxide, iron powder, and glucose.

[0018] Furthermore, the molar ratio of the cerium-based material to the reducing agent is 10:1 - 1:10.

[0019] Furthermore, in step S1, the temperature of the redox reaction is 10 - 100 °C, and the reaction time is 0.5 - 100 h.

[0020] Furthermore, in step S2, the pH value of the reaction system is regulated by adding a pH value regulating reagent.

[0021] The pH value regulating reagent includes one or more of sodium hydroxide, ammonia water, ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, sodium carbonate, rare earth hydroxide, composite rare earth hydroxide, and rare earth oxide.

[0022] Furthermore, in step S2, the pH value of the reaction system is controlled between 1 and 5.

[0023] The temperature of the precipitation reaction is 10 - 100 °C, and the precipitation reaction time is 0.5 - 100 h.

[0024] Furthermore, in step S3, the pH value at the end point of the precipitation reaction is 2.5 - 5.

[0025] Further, in step S3, the reaction temperature for maintaining the reaction at the end point pH value of the precipitation reaction is 10-100°C, and the reaction time is 0.5-24 h.

[0026] Further, in step S4, the solid-liquid separation method includes natural filtration, suction filtration or pressure filtration.

[0027] The beneficial effects of the present invention are as follows: By using the method for preparing a rare earth feed liquid with low impurities using a cerium-based material provided by the present invention, the contents of common non-rare earth impurities such as aluminum, iron, uranium, and thorium in the prepared rare earth feed liquid can be made lower, especially the content of aluminum is lower. The beneficial effects of the present invention are specifically reflected in:

[0028] (1) Using the rare earth feed liquid containing impurities as the treatment object, it has a wide range of applications;

[0029] (2) By producing impurity precipitates and efficiently adsorbing common non-rare earth impurities such as aluminum, iron, uranium, thorium, and fluorine in a reaction system with a lower pH value, a low-impurity feed liquid is prepared, which is beneficial to the subsequent rare earth extraction and separation process, increases the extraction and separation ability of the organic phase, and effectively reduces the cost of extraction and separation;

[0030] (3) The contents of uranium and thorium in the prepared low-impurity rare earth feed liquid are lower, further reducing the radioactivity of the product; at the same time, the contents of aluminum, iron, and fluorine in the prepared low-impurity rare earth feed liquid are low, and it is easier to obtain high-purity rare earth products.

[0031] Starting from the rare earth feed liquid containing impurities, the present invention innovatively combines the characteristics of the variable valence of cerium element +4 / +3 and the large surface area adsorption performance of cerium oxide matching the impurity precipitation pH value. Through the conversion between Ce 4+ / Ce 3+ and supplemented with a pH value regulator, the pH value of the reaction system is regulated to precipitate common non-rare earth impurities at a lower pH value; and through the partial dissolution of cerium dioxide, a large specific surface area of cerium is produced to match the impurity precipitation for efficient adsorption, realizing the removal of common non-rare earth impurities, and a low-impurity rare earth feed liquid is prepared through solid-liquid separation.

[0032] The method provided by the present invention can prepare a rare earth feed liquid with low contents of common non-rare earth impurities such as aluminum, iron, uranium, and thorium, which is beneficial to the progress of the rare earth separation production process and the improvement of product quality. At the same time, the method provided by the present invention conforms to the current process, has a high effective utilization rate of equipment, has the characteristics of high efficiency and short process, and is suitable for large-scale industrial production. Moreover, the method provided by the present invention has a remarkable impurity removal effect, realizing the efficient separation of rare earth and impurities such as aluminum; and it can save the calcination cost of mixed rare earth hydrochloride and the cost of subsequent extraction and separation processes, reduce the overall production cost of rare earth products, increase the product added value, and has important practical significance for giving full play to the rare earth resource advantages of our country. Description of the Drawings

[0033] Figure 1 It is a schematic flow chart of a method for preparing a rare earth feed liquid with low impurities using a cerium-based material according to an embodiment of the present invention. Specific embodiments

[0034] The technical solutions in the embodiments of the present invention will be further clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] The method for preparing a rare earth feed liquid with low impurities using a cerium-based material provided in this embodiment starts from a rare earth feed liquid containing impurities, and innovatively combines the characteristics of variable valence of cerium element +4 / +3 and the large surface area adsorption performance of cerium oxide matching the pH value of impurity precipitation. By the conversion between Ce 4+ / Ce 3+ and supplemented with a pH value regulator to control the pH value of the reaction system, common non-rare earth impurities are precipitated at a relatively low pH value; and through the partial dissolution of cerium dioxide, a large specific surface area cerium is produced to match the impurity precipitation for efficient adsorption, so as to remove common non-rare earth impurities, and a rare earth feed liquid with low impurities is prepared through solid-liquid separation.

[0036] As Figure 1 shown, a method for preparing a rare earth feed liquid with low impurities using a cerium-based material provided in an embodiment of the present invention includes the following steps:

[0037] S1. Redox: Add a cerium-based material and a reducing agent to the rare earth feed liquid containing impurities for a redox reaction;

[0038] Specifically, the redox process in step S1 is to add a certain proportion of a cerium-based material and a reducing agent to the rare earth feed liquid containing impurities, and the two are mixed and reacted at a certain temperature for a period of time. An oxidation-reduction reaction occurs between cerium dioxide in the cerium-based material and the reducing agent, and part of the cerium is dissolved out; part of the cerium element in the cerium-based material is oxidized from +4 valence to +3 valence.

[0039] Optionally, the cerium-based material is selected from one or more of cerium dioxide, cerium hydroxide, cerium dioxide-non-cerium rare earth composite material, cerium hydroxide-non-cerium rare earth composite material, cerium dioxide-non-rare earth metal composite material, cerium hydroxide-non-rare earth metal composite material, slag containing cerium dioxide, and slag containing cerium hydroxide; wherein, the proportion of cerium dioxide / cerium hydroxide is 1% to 100%.

[0040] Optionally, the rare earth feed liquid containing impurities is a hydrochloric acid and / or nitric acid rare earth solution, and the impurities in the rare earth feed liquid containing impurities include one or more of aluminum, iron, fluorine, uranium, and thorium.

[0041] Specifically, in the rare earth feed liquid containing impurities, the concentration of rare earth elements is 0.1 - 2.5 mol / L; the pH value of the rare earth feed liquid containing impurities is < 5.5.

[0042] Optionally, the reducing agent includes one or more of citric acid, thiourea, urea, hydroxylamine hydrochloride, hydrogen peroxide, iron powder, and glucose.

[0043] Optionally, the molar ratio of the cerium-based material to the reducing agent is 10:1 - 1:10; the molar ratio of the cerium-based material to the rare earth elements in the rare earth feed liquid containing impurities is 1:100 - 10:1.

[0044] Specifically, the temperature of the redox reaction is 10 - 100 °C, and the reaction time is 0.5 - 100 h.

[0045] S2. Precipitating impurities: Adjust the pH value of the reaction system, and precipitate impurities through a precipitation reaction;

[0046] Specifically, in the precipitation reaction process of step S2, by controlling the reaction degree between the cerium-based material and the reducing agent, and supplementing a certain amount of pH value regulating reagent, the purpose of controlling the pH value of the reaction system is achieved. Common non-rare earth impurities such as aluminum, iron, uranium, thorium, and fluorine in the rare earth feed liquid form precipitates as the precipitation reaction proceeds.

[0047] Optionally, in step S2, the pH value of the reaction system is adjusted by adding a certain amount of pH value regulating reagent, and the pH value regulating reagent includes one or more of sodium hydroxide, ammonia water, ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, sodium carbonate, rare earth hydroxide, composite rare earth hydroxide, and rare earth oxide.

[0048] Specifically, in step S2, the temperature of the precipitation reaction is 10 - 100 °C, the precipitation reaction time is 0.5 - 100 h, and the pH value of the reaction system is controlled between 1 and 5.

[0049] S3. Adsorbing impurities: Maintain the pH value at the end point of the precipitation reaction and continue the reaction to complete the adsorption of the impurity precipitate;

[0050] Optionally, in the process of adsorbing impurities in step S3, when the pH value reaches the end point of the impurity precipitate, the cerium-based material forms an adsorbent material with a large specific surface area due to partial dissolution of cerium dioxide, and can effectively adsorb the impurity precipitate in the liquid phase.

[0051] Optionally, in step S3, the pH value at the end point of the precipitation reaction is 2.5 - 5.

[0052] Specifically, in step S3, the reaction temperature for continuing the reaction while maintaining the pH value at the precipitation reaction end point is 10 to 100 °C, and the reaction time is 0.5 to 24 h.

[0053] S4. Solid-liquid separation: The low-impurity rare earth liquor is prepared by performing solid-liquid separation on the rare earth liquor and the solid that has adsorbed impurities.

[0054] Optionally, in step S4, the solid-liquid separation process is to perform solid-liquid separation on the rare earth liquor and the solid that has adsorbed impurities by simple methods such as natural filtration, suction filtration, or pressure filtration to obtain the low-impurity rare earth liquor.

[0055] In a specific embodiment, the impurities in the low-impurity rare earth liquor include aluminum, iron, uranium, thorium, and fluorine, where the content of aluminum is 1 to 300 mg / L, the content of iron is 1 to 300 mg / L, the content of uranium is 0.01 to 10 mg / L, the content of thorium is 0.01 to 10 mg / L, and the content of fluorine is 1 to 300 mg / L.

[0056] By using the method for preparing a low-impurity rare earth liquor with a cerium-based material provided in this embodiment, a rare earth liquor containing impurities can be used as the treatment object, and the applicable range is wide. Through the redox process, a certain proportion of cerium-based material and reducing agent are added to the rare earth liquor containing impurities. An oxidation-reduction reaction occurs between cerium dioxide in the cerium-based material and the reducing agent, and part of the cerium is dissolved out; through the process of precipitating impurities, common non-rare earth impurities such as aluminum, iron, uranium, thorium, and fluorine in the rare earth liquor form impurity precipitates in a reaction system with a lower pH value; through the process of adsorbing impurities, when the pH value reaches the end point of impurity precipitation, the cerium-based material forms an adsorbent material with a large specific surface area to effectively adsorb the impurity precipitates in the liquid phase; through the solid-liquid separation process, the rare earth liquor and the solid that has adsorbed impurities are subjected to solid-liquid separation by simple methods such as suction filtration or pressure filtration to obtain the low-impurity rare earth liquor. The method provided in this embodiment prepares a low-impurity rare earth liquor, which is beneficial to the subsequent rare earth extraction and separation process, increases the extraction and separation ability of the organic phase, effectively reduces the extraction and separation cost; moreover, the uranium and thorium contents in the prepared low-impurity rare earth liquor are lower, reducing the radioactivity of the product.

[0057] The following further illustrates the specific embodiments of the present invention through examples.

[0058] Example 1 When the rare earth liquor containing impurities is a rare earth chloride liquor obtained by dissolving a yttrium-rich rare earth ore from a southern mine with hydrochloric acid, the following method steps are used to prepare the low-impurity rare earth liquor

[0059] (1) Redox: A cerium-based material and a reducing agent are added to the rare earth liquor containing impurities for an oxidation-reduction reaction.

[0060] (2) Precipitating impurities: Adjust the pH value of the reaction system and precipitate impurities through a precipitation reaction;

[0061] (3) Adsorbing impurities: Maintain the pH value at the end point of the precipitation reaction and continue the reaction to complete the adsorption of precipitated impurities;

[0062] (4) Solid-liquid separation: Prepare the low-impurity rare earth liquor by performing solid-liquid separation on the rare earth liquor and the solid that has adsorbed impurities.

[0063] Among them, the rare earth liquor containing impurities is a rare earth chloride liquor obtained by dissolving a yttrium-rich rare earth ore from southern ore with hydrochloric acid, with a concentration of 1.55 mol / L and a pH value < 1.

[0064] The cerium-based material consists of cerium dioxide and a cerium dioxide-non-cerium rare earth composite material, and the proportion of cerium dioxide is 20%. The reducing agent consists of citric acid and thiourea, and the molar ratio of the cerium-based material to the reducing agent is 10:1. The temperature of the redox reaction is 25 °C and the reaction time is 24 h.

[0065] In step (2), the temperature of the precipitation reaction is 25 °C, the precipitation reaction time is 12 h, and the pH value of the reaction system is controlled between 1 and 3.5.

[0066] In step (3), the pH value at the end point of the precipitation reaction is 3.5, the reaction temperature for maintaining the pH value at the end point of the precipitation reaction and continuing the reaction is 25 °C, and the reaction time is 12 h.

[0067] Solid-liquid separation is carried out by suction filtration, and a low-impurity rare earth liquor with a low impurity content as shown in Table 1 can be prepared.

[0068] Table 1 Concentrations of rare earths and impurities in the initial and prepared rare earth liquors

[0069]

[0070] When the rare earth liquor containing impurities in Example 2 is a rare earth nitrate liquor obtained by dissolving a medium-yttrium rare earth ore from southern ore with nitric acid, the following method steps are used to prepare the low-impurity rare earth liquor

[0071] (1) Redox reaction: Add a cerium-based material and a reducing agent to the rare earth liquor containing impurities for a redox reaction;

[0072] (2) Precipitating impurities: Adjust the pH value of the reaction system and precipitate impurities through a precipitation reaction;

[0073] (3) Adsorbing impurities: Maintain the pH value at the end point of the precipitation reaction and continue the reaction to complete the adsorption of precipitated impurities;

[0074] (4) Solid-liquid separation: Prepare the low-impurity rare earth liquor by performing solid-liquid separation on the rare earth liquor and the solid that has adsorbed impurities.

[0075] Among them, the rare earth feed liquid containing impurities is a rare earth nitrate feed liquid obtained by dissolving yttrium rare earth ore in southern ore with nitric acid, with a concentration of 1.36 mol / L and a pH value of <2.

[0076] The cerium-based material consists of cerium hydroxide and slag enriched with cerium dioxide, and the total proportion of cerium hydroxide and cerium dioxide is 50%. The reducing agent consists of urea and hydroxylamine hydrochloride, and the molar ratio of the cerium-based material to the reducing agent is 10:3. The temperature of the redox reaction is 55 °C, and the reaction time is 15 h.

[0077] In step (2), the temperature of the precipitation reaction is 55 °C, the precipitation reaction time is 5 h, and the pH value of the reaction system is controlled between 1 and 3.8.

[0078] In step (3), the pH value at the end point of the precipitation reaction is 3.8, the reaction temperature for maintaining the pH value at the end point of the precipitation reaction and continuing the reaction is 55 °C, and the reaction time is 5 h.

[0079] Solid-liquid separation is carried out by natural filtration, and a low-impurity rare earth feed liquid with low impurity content as shown in Table 2 can be prepared.

[0080] Table 2 Concentrations of rare earths and impurities in the initial and prepared rare earth feed liquids

[0081]

[0082] When the rare earth feed liquid containing impurities in Example 3 is a rare earth chloride feed liquid obtained by dissolving light rare earth ore with hydrochloric acid, the following method steps are used to prepare a low-impurity rare earth feed liquid

[0083] (1) Redox: Add a cerium-based material and a reducing agent to the rare earth feed liquid containing impurities for a redox reaction;

[0084] (2) Precipitate impurities: Adjust the pH value of the reaction system, and precipitate impurities through a precipitation reaction;

[0085] (3) Adsorb impurities: Maintain the pH value at the end point of the precipitation reaction and continue the reaction to complete the adsorption of precipitated impurities;

[0086] (4) Solid-liquid separation: Separate the rare earth feed liquid and the solid that has adsorbed impurities by solid-liquid separation to obtain the low-impurity rare earth feed liquid.

[0087] Among them, the rare earth feed liquid containing impurities is a rare earth chloride feed liquid obtained by dissolving light rare earth ore with hydrochloric acid, with a concentration of 1.77 mol / L and a pH value of <1.

[0088] The cerium-based material consists of slag enriched with cerium hydroxide, and the proportion of cerium hydroxide is 40%. The reducing agent consists of hydrogen peroxide, and the molar ratio of the cerium-based material to the reducing agent is 10:5. The temperature of the redox reaction is 85 °C, and the reaction time is 4 h.

[0089] In step (2), the temperature of the precipitation reaction is 85 °C, the precipitation reaction time is 2 h, and the pH value of the reaction system is controlled between 1 and 4.0.

[0090] In step (3), the pH value at the end point of the precipitation reaction is 4.0, the reaction temperature for maintaining the reaction at the pH value at the end point of the precipitation reaction is 85 °C, and the reaction time is 2 h.

[0091] Solid-liquid separation is carried out by pressure filtration, and a low-impurity rare earth liquor with low impurity content as shown in Table 3 can be prepared.

[0092] Table 3 Concentrations of rare earths and impurities in the initial and prepared rare earth liquors

[0093]

[0094] It can be clearly seen from the results in Tables 1-3 that the low-impurity rare earth liquor obtained by using the method provided in the embodiment of the present invention has an impurity level at least one order of magnitude lower than that of the rare earth liquor obtained by the current acid dissolution process. Therefore, the low-impurity rare earth liquor does not need to be separately treated for impurities.

[0095] The method described in the present invention is not limited to the specific embodiments. The above embodiments are only illustrative examples of the present invention. The present invention can also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be regarded as illustrative rather than restrictive in any aspect. The scope of the present invention should be defined by the appended claims, and any changes equivalent to the intention and scope of the claims should also be included within the scope of the present invention.

Claims

1. A method for preparing a low-impurity rare earth liquid using a cerium-based material, characterized in that: The method comprises the following steps: S1, oxidation-reduction: adding a cerium-based material and a reducing agent to a rare earth liquid containing impurities to carry out an oxidation-reduction reaction; the rare earth liquid containing impurities is a hydrochloric acid and / or nitric acid rare earth solution, and the impurities in the rare earth liquid containing impurities include one or more of aluminum, iron, fluorine, uranium, and thorium; The cerium-based material is selected from one or more of cerium dioxide, cerium hydroxide, cerium dioxide-non-cerium rare earth composite material, cerium hydroxide-non-cerium rare earth composite material, cerium dioxide-non-rare earth metal composite material, cerium hydroxide-non-rare earth metal composite material, slag containing cerium dioxide, and slag containing cerium hydroxide; S2. Precipitating impurities: regulating the pH value of the reaction system to control the pH value of the reaction system between 1 and 5, and precipitating impurities through precipitation reaction, and the precipitation reaction time is 0.5 to 100 hours; S3, adsorption of impurities: maintaining the pH value at the end of the precipitation reaction and continuing the reaction to complete the adsorption of impurity precipitation, the pH value at the end of the precipitation reaction is 2.5-5, and the reaction time of maintaining the pH value at the end of the precipitation reaction and continuing the reaction is 0.5-24h; S4, solid-liquid separation: The low-impurity rare earth feed liquid is obtained by performing solid-liquid separation on the rare earth feed liquid and the solid that has adsorbed impurities.

2. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: The concentration of rare earth elements in the rare earth solution containing impurities is 0.1-2.5 mol / L; the pH value of the rare earth solution containing impurities is <5.

5.

3. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: The reducing agent includes one or more of citric acid, thiourea, urea, hydroxylamine hydrochloride, hydrogen peroxide, iron powder, and glucose.

4. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: The molar ratio of the cerium-based material to the reducing agent is 10:1 to 1:

10.

5. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: In step S1, the temperature of the redox reaction is 10-100°C, and the reaction time is 0.5-100h.

6. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: In step S2, the pH value of the reaction system is regulated by adding a pH regulating agent; The pH value regulating reagent includes one or more of sodium hydroxide, ammonia water, ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, sodium carbonate, rare earth hydroxide, composite rare earth hydroxide, and rare earth oxide.

7. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: In step S2, the temperature of the precipitation reaction is 10-100°C.

8. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: In step S3, the reaction temperature for continuing the reaction while maintaining the pH value at the end point of the precipitation reaction is 10-100°C.

9. The method for preparing a low-impurity rare earth liquid using a cerium-based material according to claim 1, characterized in that: In step S4, the solid-liquid separation method includes natural filtration, suction filtration or pressure filtration.

Images