Electrolysis method of solution containing rare earth ions

Abstract

The invention provides an electrolysis method for a solution containing rare earth ions, and relates to the technical field of hydrometallurgy, the electrolysis method comprises the following steps: taking the solution containing rare earth ions as a catholyte, carrying out electrolysis to increase the pH value of the catholyte, obtaining a turbid solution in a cathode chamber, carrying out solid-liquid separation to obtain a solid-phase substance which is a precipitate rich in rare earth or a precipitate rich in impurities, according to the method, the solid-phase substance is separated from the rare earth, so that selective separation and enrichment are realized, that is, when the solid-phase substance is a precipitate containing rare earth, the purpose of preparing a high-grade rare earth enriched substance can be achieved through electrolysis, and when the solid-phase substance is a precipitate containing impurity ions, the purpose of separating the impurity ions can be achieved through electrolysis; according to the electrolysis method, chemical reagents do not need to be added, new ions are not introduced, salt-containing wastewater is not generated, operation is easy, and the process is clean and free of pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly relates to an electrolysis method for a solution containing rare earth ions. Background Art

[0002] In recent years, with the rapid development of frontier technology fields such as new energy vehicles, artificial intelligence, quantum information, integrated circuits, catalysts, nuclear industry, aerospace and deep-sea exploration, the demand for rare earths has further increased. The exploitation volume of rare earth resources is increasing day by day, which has caused problems such as mine pollution and excessive discharge of heavy metal-containing wastewater.

[0003] On the one hand, how to efficiently and greenly enrich rare earth ions from dilute solutions containing rare earth ions and obtain high-grade enriched products has become an important topic. At present, the methods for enriching metal ions from dilute solutions mainly include chemical precipitation method, extraction method, adsorption method, ion exchange method, etc. Among them, the chemical precipitation method mainly realizes enrichment by adding excessive chemical precipitants, such as ammonium salts, alkalis, alkali metal oxides, sulfides, etc. to the dilute solution, so that the metal ions are converted into compounds with low solubility. As an efficient enrichment means, this method has the advantages of simple process and large treatment capacity. However, in this process, generally excessive chemical reagents need to be added to the dilute solution, which is easy to introduce a large number of impurity ions, generate saline wastewater, and at the same time, some chemical reagents do not participate in the reaction and co-precipitate with the target metal ions, reducing the grade of the enriched product.

[0004] For example, CN112662900B discloses a method for co-precipitation acid dissolution and selective precipitation to synergistically recover rare earths in leaching mother liquor. This method uses sodium aluminate and magnesium oxide as precipitants to prepare rare earth enriched products. In this process, a large number of impurity ions are introduced into the leaching mother liquor, reducing the rare earth grade of the enriched product and bringing the problem of saline wastewater discharge. CN113462910B discloses a method for enriching rare earth ions. This method mixes a solid organic phosphine precipitant with an alkaline liquid to obtain a saponified organic phosphonic acid solution. After mixing and reacting the saponified organic phosphonic acid solution with a rare earth ion-containing feed solution, solid-liquid separation is carried out to obtain a rare earth enriched product. In this process, an organic phosphorus-containing reagent is added, which is easy to cause phosphorus pollution and COD pollution.

[0005] On the other hand, how to efficiently separate impurity ions from a mixed solution containing rare earth ions is also an important topic. In the smelting process of rare earths, due to the similar properties of aluminum and rare earths, it is a difficult impurity ion to separate. The presence of aluminum will not only affect the extraction phase separation and efficiency, but also affect the purity of the final product. Therefore, the separation of aluminum is an unavoidable technical problem. At present, the separation of ions in a mixed solution mainly includes chemical precipitation method, adsorption method, solvent extraction method, etc.

[0006] For example, CN113699390B discloses a method for removing impurities from rare earth leaching solution. Under the condition of adding seeds, the lye is added to the rare earth leaching solution by atomized feeding to precipitate and remove iron, aluminum, and silicon impurities. After the addition of the lye is completed, CO 2 is introduced to continue the reaction for a certain period of time. After filtration, a rare earth leaching solution with low impurity content and an impurity precipitation residue with low rare earth content can be obtained. Although the chemical precipitation method has the advantage of simple operation, since chemical reagents need to be added, new impurity ions will be introduced, which will not only produce saline wastewater but also may affect the purity of the product. CN108950206B discloses a method for complexing and separating rare earth and aluminum. Specifically, organic acids such as acetic acid and methoxyacetic acid are used as complexing agents and added to a solution containing rare earth and aluminum. The pH is adjusted to 5.6 - 6.6 to precipitate and separate aluminum, obtaining a pure rare earth solution and aluminum slag. The complex can preferentially complex rare earth and does not affect the precipitation of rare earth hydroxide and aluminum hydroxide, thereby expanding the difference in the pH values of the precipitation of aluminum and rare earth and achieving the efficient separation of rare earth and aluminum. However, the complexing ability of the organic acid with rare earth is strong, and an excessive amount of sodium hydroxide needs to be added during the process of recovering rare earth. CN112063861B discloses an extraction method for separating rare earth from a high-aluminum rare earth feed solution. Using N,N-di-n-octyl-3-oxapentanediamide or N,N-diisooctyl-3-oxapentanediamide as the extractant, rare earth can be preferentially extracted. Due to the good selectivity of the extractant for rare earth, the efficient separation and recovery of rare earth from a high-aluminum rare earth feed solution are achieved; and the stripping acidity of trivalent rare earth is very low, significantly reducing the stripping acid consumption. CN108866358B discloses a method for adsorbing and removing aluminum from a rare earth feed solution by the synergistic action of complexation - ion exchange. By using a salicylic acid derivative as an organic ligand to treat the rare earth solution, and then using a D290-type resin to adsorb and remove the complex anions formed by the reaction of aluminum ions and the organic ligand. The removal rate of aluminum ions reaches more than 70%, and the loss of rare earth does not exceed 5%. However, due to the strong coordination effect between the organic ligand and rare earth, it will affect the extraction process, and a special process needs to be set up later to separate rare earth and the organic ligand.

[0007] Therefore, it is necessary to develop a new treatment method for treating solutions containing rare earth ions to achieve the purpose of preparing high-grade rare earth concentrates or separating impurity ions. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides an electrolysis method for a rare earth ion-containing solution. The electrolysis method uses the rare earth ion-containing solution as the cathode solution. Through electrolysis, the pH of the cathode solution is increased, and a turbid liquid is obtained in the cathode chamber. After solid-liquid separation, the obtained solid phase is a precipitate rich in rare earth or a precipitate rich in impurities, thereby realizing selective separation and enrichment. That is, when the solid phase is a rare earth-containing precipitate, high-grade rare earth concentrates can be prepared through electrolysis. When the solid phase is an impurity ion-containing precipitate, impurity ions can be separated through electrolysis. The electrolysis method of the present invention does not require the addition of chemical reagents, does not introduce new ions, does not generate salt-containing wastewater, and has simple operation and a clean and pollution-free process.

[0009] To achieve this purpose, the present invention adopts the following technical solutions:

[0010] The purpose of the present invention is to provide an electrolysis method for a rare earth ion-containing solution. The electrolysis method includes the following contents:

[0011] Using the rare earth ion-containing solution as the cathode solution and placing it in the cathode chamber, placing the anode solution in the anode chamber, separating the cathode chamber from the anode chamber with an ion exchange membrane. Through electrolysis, the pH of the cathode solution is increased, and a turbid liquid is obtained in the cathode chamber. After solid-liquid separation, the obtained solid phase is a precipitate rich in rare earth or a precipitate rich in impurities, thereby realizing selective separation and enrichment.

[0012] The electrolysis method of the present invention uses the rare earth ion-containing solution as the cathode solution. Through electrolysis, the pH of the cathode solution is increased, and a turbid liquid is obtained in the cathode chamber. After solid-liquid separation, the obtained solid phase is a precipitate rich in rare earth or a precipitate rich in impurities, thereby realizing selective separation and enrichment. That is, when the solid phase is a rare earth-containing precipitate, high-grade rare earth concentrates can be prepared through electrolysis. When the solid phase is an impurity ion-containing precipitate, impurity ions can be separated through electrolysis. The electrolysis method of the present invention does not require the addition of chemical reagents, does not introduce new ions, does not generate salt-containing wastewater, and has simple operation and a clean and pollution-free process.

[0013] When high-grade rare earth concentrates need to be prepared, the traditional chemical precipitation method generally requires adding an excessive amount of precipitant to the rare earth ion-containing solution, which will produce saline wastewater or co-precipitate with impurity ions, reducing the grade of the rare earth concentrate. The main principle of preparing concentrates by the electrochemical method is that the hydroxide ions generated by the hydrogen evolution reaction occurring on the cathode surface combine with the rare earth ions in the solution to produce hydroxide or basic salt precipitates, thereby realizing the separation and enrichment of rare earth ions from the solution. Compared with the traditional neutralization enrichment process, the electrochemical enrichment process has the advantages of being green and pollution-free. This process does not introduce new impurity ions, can effectively improve the grade of the concentrate, and does not produce saline wastewater. At the same time, during the electrochemical precipitation process, a certain concentration of acid can be generated in the middle chamber or the anode chamber and can be recycled for production.

[0014] When impurity ions need to be separated from a rare earth ion-containing solution, the existing neutralization precipitation method requires adding additional neutralization precipitation reagents, which will introduce new impurity ions, produce saline wastewater, and it is difficult to add continuously and evenly, inevitably resulting in co-precipitation phenomena and large losses of rare earth ions due to co-precipitation. The principle of separating impurity ions by the electrochemical method is that the precipitation potential of impurity ions is more negative. The hydrogen evolution reaction occurs in the cathode chamber, and the concentration of hydroxide ions gradually increases, and the pH slowly rises, which can cause the impurity ions to gradually hydrolyze and precipitate. By precisely controlling the hydrogen evolution rate during the electrolysis process, and then controlling the alkali production rate and the pH of the solution to match the hydrolysis rate of the impurity ions, selective precipitation of the impurity ions is achieved, thereby avoiding excessive co-precipitation losses of rare earth ions due to local over-alkalinity. The electrolysis method described in the present invention does not require adding chemical reagents, does not introduce new ions, does not produce saline wastewater, and has simple operation and good separation effect. At the same time, during the electrolysis process, a certain concentration of acid can be generated in the middle chamber or the anode chamber and can be recycled for production.

[0015] It should be noted that the electrolysis method described in the present invention needs to make a simple judgment based on the types and contents of impurity ions in the rare earth ion-containing solution to be treated, and then determine whether the actual requirement is to enrich or separate impurities, and focus on controlling the pH value of the cathode solution after electrolysis to achieve the ideal technical effect.

[0016] It should be noted that the anions of the rare earth ion-containing solution described in the present invention include any one or a combination of at least two of sulfate, nitrate, acetate or chloride ions, and it is judged whether to set up a middle chamber according to the anion of the rare earth ion-containing solution including chloride ions.

[0017] As a preferred technical solution of the present invention, the anion of the rare earth ion-containing solution includes chloride ions. An intermediate chamber is provided between the cathode chamber and the anode chamber. The cathode chamber is separated from the intermediate chamber by an anion exchange membrane, and the intermediate chamber is separated from the anode chamber by a cation exchange membrane. Hydrochloric acid solution is used as the intermediate chamber liquid and placed in the intermediate chamber. Through electrolysis, the hydrogen ion concentration of the hydrochloric acid solution can be increased, and acid can be produced at the same time.

[0018] As a preferred technical solution of the present invention, the initial hydrogen ion concentration of the hydrochloric acid solution is 0.1 - 0.5 mol / L, such as 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable.

[0019] As a preferred technical solution of the present invention, the hydrogen ion concentration of the hydrochloric acid solution after electrolysis is 0.5 - 1 mol / L, such as 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L or 1.0 mol / L, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable.

[0020] As a preferred technical solution of the present invention, the anion of the rare earth ion-containing solution does not include chloride ions, and the cathode chamber is separated from the anode chamber by an anion exchange membrane.

[0021] It should be noted that in the electrolysis method of the present invention, if the anion of the cathode liquid includes chloride ions, only the cathode chamber and the anode chamber separated by an anion exchange membrane are provided. During electrolysis, chloride ions will enter the anode chamber from the cathode chamber through the anion exchange membrane, and chloride ions will lose electrons on the anode to become highly toxic chlorine gas, thus causing potential safety hazards. Therefore, if the anion of the cathode liquid includes chloride ions, an intermediate chamber is provided between the cathode chamber and the anode chamber, and hydrochloric acid solution is used as the intermediate chamber liquid and placed in the intermediate chamber. During electrolysis, chloride ions will enter the intermediate chamber from the cathode chamber through the anion exchange membrane, and hydrogen ions will enter the intermediate chamber from the anode chamber through the cation exchange membrane, so that the hydrogen ion concentration of the hydrochloric acid solution is increased to produce acid, which can be recycled for the acid dissolution process and production, and has significant economic and environmental advantages.

[0022] As a preferred technical solution of the present invention, the rare earth ion concentration in the rare earth ion-containing solution is 0.1-300 g / L, such as 0.1 g / L, 0.5 g / L, 1 g / L, 5 g / L, 10 g / L, 30 g / L, 50 g / L, 70 g / L, 90 g / L, 100 g / L, 150 g / L, 200 g / L, 230 g / L, 250 g / L, 280 g / L or 300 g / L, etc., but not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0023] As a preferred technical solution of the present invention, the cations in the anolyte include any one or a combination of at least two of hydrogen ions, sodium ions, potassium ions, magnesium ions or ammonium ions, and the anions in the anolyte include sulfate ions and / or nitrate ions.

[0024] It should be noted that the anolyte of the present invention can be either an inorganic acid solution of sulfuric acid and / or nitric acid, or an inorganic salt solution of one or several of sodium, potassium, magnesium, ammonium sulfates or nitrates, or a mixed solution of the above inorganic acids and inorganic salts. Because when there is no need to set up an intermediate chamber, the hydrogen ion concentration in the anolyte increases, and by-product acid can be used for industrial production. Therefore, those skilled in the art can reasonably select the specific type of anolyte according to the actual demand for inorganic acids. Moreover, when there is no need to set up an intermediate chamber, the initial hydrogen ion concentration in the anolyte is 0.1-0.7 mol / L, such as 0.1 mol / L, 0.3 mol / L, 0.5 mol / L or 0.7 mol / L, etc., but not limited to the listed values, and other unlisted values within the above numerical range are equally applicable. After electrolysis, the hydrogen ion concentration in the anolyte is 0.4-1.5 mol / L, such as 0.4 mol / L, 0.7 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L or 1.5 mol / L, etc., but not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0025] As a preferred technical solution of the present invention, the current density of the electrolysis is 3-500 A / m 2 For example, 3 A / m 2 、5 A / m 2 、10 A / m 2 、30 A / m 2 、50 A / m 2 、80 A / m 2 、100 A / m 2 、200 A / m 2 、300 A / m 2 、400 A / m 2 Or 500 A / m 2etc., but not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0026] As a preferred technical solution of the present invention, the pH of the cathode solution after electrolysis is 1-9.5, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 9.5, etc., but not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0027] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0028] (1) In the electrolysis method of the present invention, a rare earth ion-containing solution is used as the cathode solution. Through electrolysis, the pH of the cathode solution increases, and a turbid liquid is obtained in the cathode chamber. After solid-liquid separation, the obtained solid phase is a rare earth-rich precipitate or an impurity-rich precipitate, thereby realizing selective separation and enrichment. That is, when the solid phase is a rare earth-containing precipitate, high-grade rare earth concentrate can be prepared through electrolysis. When the solid phase is an impurity ion-containing precipitate, impurity ions can be separated through electrolysis;

[0029] (2) The electrolysis method of the present invention does not require the addition of chemical reagents, does not introduce new ions, does not produce salt-containing wastewater, and has simple operation and a clean and pollution-free process. Detailed implementation manners

[0030] To facilitate the understanding of the present invention, the following examples are listed for the present invention. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0031] Example 1

[0032] This example provides an electrolysis method for a rare earth ion-containing solution. The electrolysis method includes the following contents:

[0033] Using a mine leaching solution containing 0.1 g / L rare earth as the cathode solution and placing it in the cathode chamber, where the anion is sulfate ion, using a sulfuric acid solution with a hydrogen ion concentration of 0.1 mol / L as the anode solution and placing it in the anode chamber, separating the cathode chamber from the anode chamber with an anion exchange membrane, and performing electrolysis at a current density of 3 A / m 2 until the pH of the cathode solution rises to 9.0; a turbid liquid is obtained in the cathode chamber. After solid-liquid separation, the obtained solid phase is the rare earth concentrate, and the grade of the rare earth concentrate is 55%; the hydrogen ion concentration of the anode solution increases to 0.4 mol / L, and by-product acid can be used for industrial production.

[0034] Example 2

[0035] This example provides an electrolysis method for a rare earth ion-containing solution. The electrolysis method includes the following contents:

[0036] Using an acetic acid solution containing 10 g / L of mixed rare earths as the cathode solution and placing it in the cathode chamber, and using a mixed sulfate solution containing 0.1 mol / L of hydrogen ions, 0.1 mol / L of sodium sulfate, and 0.1 mol / L of magnesium sulfate as the anode solution and placing it in the anode chamber. An anion exchange membrane is used to separate the cathode chamber from the anode chamber, and electrolysis is carried out at a current density of 100 A / m 2 until the pH of the cathode solution rises to 9.5; a turbid liquid is obtained in the cathode chamber, and after solid-liquid separation, the obtained solid phase is the rare earth enrichment, and the grade of the rare earth enrichment is 56%; the hydrogen ion concentration of the anode solution increases to 0.5 mol / L, and the by-product acid can be used for industrial production.

[0037] Example 3

[0038] This example provides an electrolysis method for a rare earth ion-containing solution, and the electrolysis method includes the following content:

[0039] Using a mine leaching solution containing RE 3+ , Al 3+ , Mg 2+ as the cathode solution and placing it in the cathode chamber, where the concentrations of RE 3+ , Al 3+ , Mg 2+ are 0.50 g / L, 0.03 g / L, and 1.25 g / L respectively, and the sulfate ion concentration is 6 g / L. Using a mixed sulfate solution containing 0.7 mol / L of hydrogen ions, 0.15 mol / L of potassium sulfate, and 0.15 mol / L of ammonium sulfate as the anode solution and placing it in the anode chamber. An anion exchange membrane is used to separate the cathode chamber from the anode chamber, and electrolysis is carried out at a current density of 10 A / m 2 until the pH of the cathode solution rises to 4.9;

[0040] A turbid liquid is obtained in the cathode chamber, and Al 3+ undergoes a precipitation reaction, and RE 3+ , Mg 2+ remain in the solution. After solid-liquid separation, a solution containing RE 3+ , Mg 2+ and a solid phase containing Al 3+ can be obtained. After detection, the concentrations of RE 3+ , Al 3+ , Mg 2+ in the obtained solution are 0.47 g / L, 0.005 g / L, and 1.25 g / L respectively. The precipitation rate of Al 3+ is 83%, the precipitation rate of RE 3+ is 6%, and the precipitation rate of Mg 2+The precipitation rate is 0; when the hydrogen ion concentration of the anolyte increases to 1.5 mol / L, by-product acid can be obtained for industrial production.

[0041] Example 4

[0042] This example provides an electrolysis method for a rare earth ion-containing solution. The electrolysis method includes the following steps:

[0043] Using a rare earth chloride stripping solution containing La 3+ and Al 3+ as the catholyte and placing it in the cathode chamber, where the concentrations of La 3+ and Al 3+ are 300 g / L and 0.12 g / L respectively, using a 0.3 mol / L nitric acid solution as the anolyte and placing it in the anode chamber. An intermediate chamber is set between the cathode chamber and the anode chamber. An anion exchange membrane is used to separate the cathode chamber from the intermediate chamber, and a cation exchange membrane is used to separate the intermediate chamber from the anode chamber. A 0.1 mol / L hydrochloric acid solution is used as the intermediate chamber liquid and placed in the intermediate chamber. Electrolysis is carried out at a current density of 500 A / m 2 until the pH of the catholyte rises to 5.9;

[0044] A turbid liquid is obtained in the cathode chamber. Al 3+ undergoes a precipitation reaction, and La 3+ remains in the solution. After solid-liquid separation, a solution containing La 3+ and a solid phase containing Al 3+ can be obtained. After detection, the concentrations of La 3+ and Al 3+ in the obtained solution are 279 g / L and 0.009 g / L respectively. The precipitation rate of Al 3+ is 92.5%, and the precipitation rate of La 3+ is 5%; the hydrogen ion concentration of the intermediate chamber liquid increases to 0.5 mol / L, and the hydrogen ion concentration of the anolyte increases to 1 mol / L, and by-product acid can be obtained for industrial production.

[0045] Example 5

[0046] This example provides an electrolysis method for a rare earth ion-containing solution. The electrolysis method includes the following steps:

[0047] Using a scandium-containing titanium-zirconium mixed chloride solution as the cathode solution and placing it in the cathode chamber, where the concentrations of scandium, titanium, and zirconium are 6 g / L, 4 g / L, and 9 g / L respectively. Using a sulfuric acid solution with 0.7 mol / L hydrogen ions as the anode solution and placing it in the anode chamber. An intermediate chamber is set between the cathode chamber and the anode chamber. An anion exchange membrane is used to separate the cathode chamber from the intermediate chamber, and a cation exchange membrane is used to separate the intermediate chamber from the anode chamber. Using a 0.5 mol / L hydrochloric acid solution as the intermediate chamber solution and placing it in the intermediate chamber. Electrolysis is carried out at a current density of 300 A / m 2 until the pH of the cathode solution rises to 1;

[0048] A turbid liquid is obtained in the cathode chamber, causing precipitation reactions of titanium and zirconium, with scandium remaining in the solution. The obtained turbid liquid is heated to 90 °C and then subjected to solid-liquid separation to obtain a scandium-containing solution and a titanium-zirconium-containing solid phase. After detection, the concentrations of scandium, titanium, and zirconium in the obtained solution are 5.4 g / L, 0.04 g / L, and 0.09 g / L respectively. The precipitation rate of titanium is 99%, the precipitation rate of zirconium is 99%, and the precipitation rate of scandium is 10%. The hydrogen ion concentration in the intermediate chamber solution increases to 1 mol / L, and the hydrogen ion concentration in the anode solution increases to 1.5 mol / L, and by-product acid can be used for industrial production.

[0049] Comparative Example 1

[0050] This comparative example provides a chemical precipitation method for a rare earth ion-containing solution. Using the mine leaching solution containing 0.1 g / L rare earth described in Example 1 as the raw material, the chemical precipitation method includes the following content:

[0051] Using the mine leaching solution containing 0.1 g / L rare earth as the raw material, adding magnesium oxide to raise the pH of the solution to 9.0 to obtain a turbid liquid. After solid-liquid separation, the obtained solid phase is the rare earth concentrate, and the grade of the rare earth concentrate is 11%.

[0052] Comparative Example 2

[0053] This comparative example provides a chemical precipitation method for a rare earth ion-containing solution. Using the rare earth chloride stripping solution containing La 3+ , Al 3 + described in Example 4 as the raw material, the chemical precipitation method includes the following content:

[0054] Using the rare earth chloride stripping solution containing La 3+ , Al 3+ as the raw material, where the concentrations of La 3+ , Al 3+ are 300 g / L and 0.12 g / L respectively. Adding ammonia water to adjust the pH of the solution to 5.9 to obtain a turbid liquid, and Al 3+ undergoes a precipitation reaction, and La3+ Remain in the solution. After solid-liquid separation, a solution containing La 3+ and a solid phase containing Al 3+ can be obtained. After detection, the concentrations of La 3+ and Al 3+ in the obtained solution are 219 g / L and 0.009 g / L respectively. The precipitation rate of Al 3+ is 92.5%, and the precipitation rate of La 3+ is 27%.

[0055] It can be seen that in Examples 1-2 of the present invention, the purpose of preparing high-grade rare earth concentrates is achieved by the electrolysis method, and in Examples 3-5 of the present invention, the purpose of separating impurity ions is achieved by the electrolysis method.

[0056] In summary, the electrolysis method of the present invention uses a rare earth ion-containing solution as the cathode solution. Through electrolysis, the pH of the cathode solution increases, and a turbid liquid is obtained in the cathode chamber. After solid-liquid separation, the obtained solid phase is a precipitate rich in rare earth or a precipitate rich in impurities, thereby realizing selective separation and enrichment. That is, when the solid phase is a rare earth-containing precipitate, the purpose of preparing high-grade rare earth concentrates can be achieved by electrolysis, and when the solid phase is an impurity ion-containing precipitate, the purpose of separating impurity ions can be achieved by electrolysis; the electrolysis method of the present invention does not require the addition of chemical reagents, does not introduce new ions, does not generate saline wastewater, and has simple operation and a clean and pollution-free process.

[0057] The present invention uses the above-mentioned examples to illustrate the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An electrolysis method for a rare earth ion-containing solution, characterized in that, the electrolysis method comprises the following: Using the rare earth ion-containing solution as the cathode solution and placing it in the cathode chamber, placing the anode solution in the anode chamber, separating the cathode chamber from the anode chamber with an ion exchange membrane, electrolyzing to increase the pH of the cathode solution, obtaining a turbid liquid in the cathode chamber, and through solid-liquid separation, the obtained solid phase is a precipitate rich in rare earth or a precipitate rich in impurities, thereby realizing selective separation and enrichment.

2. The electrolysis method according to claim 1, characterized in that, the anion of the rare earth ion-containing solution includes chloride ions, an intermediate chamber is arranged between the cathode chamber and the anode chamber, the cathode chamber is separated from the intermediate chamber with an anion exchange membrane, and the intermediate chamber is separated from the anode chamber with a cation exchange membrane; Placing hydrochloric acid solution as the intermediate chamber solution in the intermediate chamber.

3. The electrolysis method according to claim 2, characterized in that, the initial hydrogen ion concentration of the hydrochloric acid solution is 0.1 - 0.5 mol / L, and the hydrogen ion concentration of the hydrochloric acid solution after electrolysis is 0.5 - 1 mol / L.

4. The electrolysis method according to claim 1, characterized in that, the anion of the rare earth ion-containing solution does not include chloride ions, and the cathode chamber is separated from the anode chamber with an anion exchange membrane.

5. The electrolysis method according to any one of claims 1 - 4, characterized in that, the rare earth ion concentration of the rare earth ion-containing solution is 0.1 - 300 g / L.

6. The electrolysis method according to any one of claims 1 - 5, characterized in that, the cations of the anode solution include any one or a combination of at least two of hydrogen ions, sodium ions, potassium ions, magnesium ions or ammonium ions, and the anions of the anode solution include sulfate ions and / or nitrate ions.

7. The electrolysis method according to any one of claims 1 - 6, characterized in that, The current density of the electrolysis is 3 - 500 A / m 2 .

8. The electrolysis method according to any one of claims 1 - 7, characterized in that, the pH of the cathode solution after electrolysis is 1 - 9.5.