Method for preparing high-purity rare earth by mixed elution ion exchange

Abstract

The application discloses a method for preparing high-purity rare earth by mixed elution ion exchange, which comprises the following steps: firstly, several ion exchange columns are divided into adsorption columns and separation columns, and ion exchange resins are filled into the adsorption columns and the separation columns respectively, then the adsorption columns and the separation columns are washed by pure water, hydrochloric acid solution or nitric acid solution and ammonia water solution respectively; then, rare earth solution is added into the adsorption columns to adsorb rare earth ions; meanwhile, any one of citric acid, tartaric acid, HEDTA, EDTA, NTA, ammonium acetate, DCTA, DTPA, lactic acid and malic acid is selected as eluent A, eluent B or eluent C, and then the eluents are prepared into main eluent, mixed eluent I and mixed eluent II; the adsorption columns and the separation columns are connected in a head-to-tail mode, then elution is carried out, eluate is collected in sections, and then oxalic acid is used for precipitation, and the obtained precipitate is calcined to obtain high-purity rare earth oxide. The application solves the problems of poor separation capacity, large consumption and high separation cost of single eluent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rare earth preparation, and particularly relates to a method for preparing high-purity rare earth by mixed elution ion exchange. BACKGROUND

[0002] Rare earth is known as "industrial vitamin", and is a new type of functional material with multiple properties such as magnetism, light and electricity. The requirements for rare earth raw materials are generally high for laser materials, superconducting materials, medical care, national defense and military industry and other cutting-edge products. It is difficult to meet the requirements of high-purity rare earth preparation by ordinary solvent extraction method. At present, ion exchange technology is mainly used for the preparation of high-purity rare earth compounds with high-end requirements, but there are still a series of problems in practical application, which restrict the low-cost and large-scale production of high-purity rare earth compounds. Ion exchange technology mainly relies on the exchange of ions in solid ion exchanger and ions in mixed rare earth solution, and the stability difference of complex compounds formed by the ion exchanger and the complexing agent to achieve the purpose of purification. However, due to the close chemical properties between different rare earth ions, the complexing stability constant of single eluent used in common ion exchange technology is small (see Table 1), and the separation capacity is limited, resulting in low separation efficiency, low product purity and high cost, which limits the large-scale application of ion exchange technology. Therefore, developing a new mixed elution ion exchange method for preparing high-purity rare earth can help to solve the problems of improving the production efficiency and reducing the production cost of high-purity rare earth, and solving the problem of low purity of rare earth products.

[0003] Table 1: Stability constant of rare earth and complexing agent

[0004] SUMMARY

[0005] In view of the above problems, the application discloses a method for preparing high-purity rare earth by mixed elution ion exchange, which realizes accurate and efficient separation of impurities to be separated by changing the ratio of different eluents, solves the problems of poor separation capacity, high consumption and high separation cost of single eluent, and provides a new path for rapid and efficient preparation of high-purity rare earth.

[0006] The application is realized by adopting the following technical scheme:

[0007] A method for preparing high-purity rare earth by mixed elution ion exchange, comprising the following steps:

[0008] (1) Ion exchange device preparation: a plurality of ion exchange columns are divided into adsorption columns and separation columns, the number ratio of the adsorption columns and the separation columns is 1: (2-6), ion exchange resins are filled into the adsorption columns and the separation columns respectively, and the filling height is 80-100%; the adsorption columns and the separation columns are washed with pure water respectively, and then washed with hydrochloric acid solution or nitric acid solution respectively, and converted into H +Type resin, and then washing with pure water to remove excess hydrochloric acid or nitric acid, and then washing with ammonia solution to convert to NH + Type resin, and then washing with pure water to remove excess hydrochloric acid or nitric acid, and then washing with ammonia solution to convert to NH

[0009] (2) Adsorption column adsorbs rare earth ions: taking the adsorption column obtained in step (1), adding a rare earth solution into the adsorption column, and when the eluate becomes turbid by detecting with an oxalic acid aqueous solution, washing the excess rare earth solution in the adsorption column with pure water;

[0010] (3) Preparation of eluent: selecting any one of citric acid, tartaric acid, HEDTA, EDTA, NTA, ammonium acetate, DCTA, DTPA, lactic acid, and malic acid as eluent A or eluent B or eluent C, and the eluent A, eluent B, and eluent C are all different; dissolving the eluent A in an ammonia solution to obtain a main eluent; adding the eluent B into the main eluent and mixing to obtain a mixed eluent I; adding the eluent C into the main eluent and mixing to obtain a mixed eluent II;

[0011] (4) connecting the adsorption column treated in step (2) and the separation column treated in step (1) in series, and then performing elution, and the elution process is any one of the following three process modes:

[0012] The first process mode is adding the mixed eluent I into the adsorption column to perform first elution, and then adding the main eluent to perform second elution, and during the first elution and the second elution, when the eluate of the last separation column becomes turbid by detecting with an oxalic acid aqueous solution, immediately starting to collect the eluate, and collecting the eluate of the second elution in stages, and then performing segmented precipitation with oxalic acid, washing the precipitate with pure water, and then calcining the precipitate at high temperature to obtain high-purity rare earth oxides;

[0013] The second process mode is adding the main eluent into the adsorption column to perform first elution, and then adding the mixed eluent I to perform second elution, and during the first elution and the second elution, when the eluate of the last separation column becomes turbid by detecting with an oxalic acid aqueous solution, immediately starting to collect the eluate, and collecting the eluate of the first elution and the second elution in stages, and then performing segmented precipitation with oxalic acid, washing the precipitate with pure water, and then calcining the precipitate at high temperature to obtain high-purity rare earth oxides;

[0014] The third process mode is that mixed eluent I is added to start the adsorption column for primary elution, then the main eluent is added for secondary elution, and then mixed eluent II is added for tertiary elution. During the primary elution, the secondary elution and the tertiary elution, when the eluate of the last separation column is detected to be turbid by oxalic acid aqueous solution, the eluate is immediately collected, and the eluates of the secondary elution and the tertiary elution are collected in stages. Then, the eluate is precipitated by oxalic acid, and the precipitate is washed by pure water. After that, the precipitate is calcined at high temperature to obtain high-purity rare earth oxide.

[0015] In the process of preparing the mixed eluent, the main eluent is prepared by selecting appropriate eluent A according to the separation coefficient of the element to be purified and the impurity element. The eluent A is any one of citric acid, tartaric acid, HEDTA, EDTA, NTA, ammonium acetate, DCTA, DTPA, lactic acid and malic acid. Then, the atomic numbers are arranged from small to large. The impurity element with an atomic number smaller than the element to be purified is a rear impurity element, and the impurity element with an atomic number greater than the element to be purified is a front impurity element. The elution control section is selected according to the complex stability constant of the element to be purified and the front or rear impurity element and the impurity content requirement. The product of the complex stability constant and the corresponding impurity content requirement of the two impurity elements is compared. The smaller product determines the elution control section. The smaller product corresponding to the front impurity element determines the front elution control section, and the smaller product corresponding to the rear impurity element determines the rear elution control section. Then, the appropriate second and subsequent eluents are selected according to the elution control section. For example, the eluent with a complex constant greater than the main eluent is selected for the front elution control section to quickly remove the impurities in the control section and achieve efficient separation. The front impurity element will be separated before the element to be purified. The eluent with a complex constant less than the main eluent is selected for the rear elution control section to delay the impurities in the control section and achieve efficient separation. The rear impurity element will be separated later than the element to be purified. After determining the direction, the compatibility between the mixed eluents is considered to determine the types of eluents B and C. Finally, the amounts of eluents B and C are determined according to the content of all impurities to be separated in the elution control section. Generally, the amount is determined as 0.5-1000 times, preferably 10 times, of the theoretical exchange measurement ratio.

[0016] The front elution control section can be eluted and separated by the mixed eluent first, and the remaining main eluent can be used as a single eluent for elution and separation. The rear elution control section can be eluted and separated by the mixed eluent after using the main eluent as a single eluent for elution. When the front and rear impurities are both required to be high, the method of using the mixed eluent for the front elution control section and then using the mixed eluent for the rear elution control section can be adopted.

[0017] The present application introduces mixed eluent, effectively controls rare earth impurities in front section or rear section of main rare earth elements, improves separation coefficient among rare earth elements, realizes efficient and rapid separation, and realizes preparation of super-high-purity rare earth products.

[0018] Further, the length of the ion exchange column is 0.3-3 m, and the inner diameter is 1-50 cm.

[0019] Further, the ion exchange resin is any one of strong acid styrene cationic resin and weak acid styrene cationic resin, and the particle size of the ion exchange resin is 0.01-100 μm.

[0020] Further, the concentration of the hydrochloric acid solution is 0.01-5 mol / L, the concentration of the nitric acid solution is 0.12-5 mol / L, and the concentration of the ammonia solution is 0.1-3 mol / L.

[0021] Further, the rare earth solution in step (2) is a chlorinated rare earth solution or a nitric acid rare earth solution, and the concentration of the rare earth solution is 0.01-2 mol / L.

[0022] Further, in step (3), 0.001-0.1 mol of eluent A is contained in 1 L of the main eluent. By controlling the concentration of eluent A in the main eluent, it is beneficial to control the eluent dosage while ensuring the effect and elution efficiency of the main eluent, thereby reducing the production cost.

[0023] Further, in step (3), the volume of the mixed eluent I is 0.001-1 times the volume of the main eluent, and the volume of the mixed eluent II is 0.001-1 times the volume of the main eluent.

[0024] Further, a retarder is added to the separation column treated in step (1), and after the eluate turns blue, the excess retarder is washed away with pure water. The retarder is obtained by mixing copper nitrate and nitric acid solution, the molar ratio of the copper nitrate and the nitric acid is 1: (0.1-1), the molar ratio of the copper nitrate and the nitric acid is preferably 1:0.5, and the concentration of the copper nitrate in the retarder is 50 g / L.

[0025] Further, in step (4), the adsorption column treated in step (2) and the separation column eluted with the retarder are connected in series, and then elution is performed. The elution process is any one of the following three process modes:

[0026] The first process mode is that mixed eluent I is added to the adsorption column for primary elution, then the main eluent is added for secondary elution, during the primary elution and the secondary elution, when the eluate of the last separation column changes from blue to transparent and becomes turbid by oxalic acid solution, the eluate is immediately collected, the eluate of the primary elution and the secondary elution is collected in stages, then the sedimentation is carried out by oxalic acid, the sediment is washed by pure water, and the high-purity rare earth oxide is obtained by burning the sediment at high temperature;

[0027] The second process mode is that the main eluent is added to the adsorption column for primary elution, then the mixed eluent I is added for secondary elution, during the primary elution and the secondary elution, when the eluate of the last separation column changes from blue to transparent and becomes turbid by oxalic acid solution, the eluate is immediately collected, the eluate of the primary elution and the secondary elution is collected in stages, then the sedimentation is carried out by oxalic acid, the sediment is washed by pure water, and the high-purity rare earth oxide is obtained by burning the sediment at high temperature;

[0028] The third process mode is that the mixed eluent I is added to the adsorption column for primary elution, then the main eluent is added for secondary elution, and then the mixed eluent II is added for tertiary elution, during the primary elution, the secondary elution and the tertiary elution, when the eluate of the last separation column changes from blue to transparent and becomes turbid by oxalic acid solution, the eluate is immediately collected, the eluate of the secondary elution and the tertiary elution is collected in stages, then the sedimentation is carried out by oxalic acid, the sediment is washed by pure water, and the high-purity rare earth oxide is obtained by burning the sediment at high temperature.

[0029] Compared with the prior art, the technical scheme has the following beneficial effects:

[0030] The technical scheme effectively improves the ion exchange separation efficiency, reduces the consumption of the main eluent, reduces the production cost of the high-purity rare earth oxide produced by the ion exchange method, and improves the product purity. DETAILED DESCRIPTION

[0031] The present application is further described by the following examples, but is not limited to the following examples. The specific experimental conditions and methods not mentioned in the following examples are generally conventional methods well known to those skilled in the art.

[0032] Example 1: A method for preparing high-purity rare earth by mixed elution ion exchange method, comprising the following steps:

[0033] (1) Ion exchange device preparation: take several ion exchange columns and divide them into adsorption columns and separation columns, the number ratio of the adsorption columns and the separation columns is 1:3, fill the ion exchange resin into the adsorption columns and the separation columns respectively, the filling height is 90%; wash the adsorption columns and the separation columns with pure water respectively, then wash them with hydrochloric acid solution respectively, convert them into H + type resin, then wash them with pure water to remove excess hydrochloric acid, and then wash them with ammonia solution to convert them into NH + type resin, then wash them with pure water to remove excess ammonia; the length of the ion exchange column is 1 m, and the inner diameter is 10 cm; the ion exchange resin is strong acid styrene cation exchange resin, and the particle size of the ion exchange resin is 10 μm; the concentration of the hydrochloric acid solution is 1 mol / L, and the concentration of the ammonia solution is 1 mol / L;

[0034] (2) Adsorption of rare earth ions by the adsorption column: take the adsorption column obtained by step (1), add a rare earth solution into the adsorption column, and then wash the excess rare earth solution in the adsorption column with pure water after the eluate becomes turbid when detected with an oxalic acid aqueous solution; the rare earth solution is praseodymium chloride solution, and the concentration of the rare earth solution is 0.2 mol / L;

[0035] (3) Preparation of eluent: select ammonium acetate as eluent A, and select EDTA as eluent B; dissolve eluent A in an ammonia solution to obtain a main eluent; add eluent B into the main eluent and mix them uniformly to obtain a mixed eluent I; 0.1 mol of eluent A is contained in every 1 L of the main eluent; the volume of the mixed eluent I is 0.2 times the volume of the main eluent, and the amount of eluent B is 10 times the theoretical amount;

[0036] (4) Connect the adsorption column treated by step (2) and the separation column treated by step (1) end to end, and then perform elution, the elution process is as follows: add the mixed eluent I into the adsorption column to perform first elution, then add the main eluent to perform second elution, and immediately start collecting the eluate when the eluate of the last separation column becomes turbid when detected with an oxalic acid aqueous solution, and collect the eluate of the second elution in stages, then perform segmented precipitation with oxalic acid, wash the precipitate with pure water, and then obtain high-purity rare earth oxide by calcining the precipitate at high temperature, and the obtained rare earth oxide is praseodymium oxide, and the purity reaches 99.9999%.

[0037] Example 2: A method for preparing high-purity rare earth by a mixed elution ion exchange method, which comprises the following steps:

[0038] (1) Ion exchange device preparation: take several ion exchange columns and divide them into adsorption columns and separation columns, the number ratio of the adsorption columns and the separation columns is 1:2, fill ion exchange resin into the adsorption columns and the separation columns respectively, the filling height is 80%; wash the adsorption columns and the separation columns with pure water respectively, then wash them with hydrochloric acid solution respectively, convert them into H + type resin, then wash them with pure water to remove excess hydrochloric acid, and then wash them with ammonia solution to convert them into NH + type resin, then wash them with pure water to remove excess ammonia; the length of the ion exchange column is 3 m, and the inner diameter is 50 cm; the ion exchange resin is strong acid styrene cation exchange resin, and the particle size of the ion exchange resin is 100 μm; the concentration of the hydrochloric acid solution is 0.01 mol / L, and the concentration of the ammonia solution is 0.1 mol / L;

[0039] (2) Adsorption of rare earth ions by the adsorption column: take the adsorption column obtained by step (1), add a rare earth solution into the adsorption column, and then wash away the excess rare earth solution in the adsorption column with pure water when the eluate becomes turbid by detecting it with an oxalic acid aqueous solution; the rare earth solution is praseodymium chloride solution, and the concentration of the rare earth solution is 0.01 mol / L;

[0040] (3) Preparation of eluent: select ammonium acetate as eluent A, and select EDTA as eluent B; dissolve eluent A in an ammonia solution to obtain a main eluent; add eluent B into the main eluent and mix them uniformly to obtain a mixed eluent I; 0.02 mol of eluent A is contained in every 1 L of the main eluent; the volume of the mixed eluent I is 0.001 times the volume of the main eluent, and the amount of eluent B is 0.5 times the theoretical amount;

[0041] (4) Connect the adsorption column treated by step (2) and the separation column treated by step (1) end to end, and then perform elution, the elution process is as follows: add the mixed eluent I into the adsorption column to perform first elution, then add the main eluent to perform second elution, and when the eluate of the last separation column becomes turbid by detecting it with an oxalic acid aqueous solution, immediately start to collect the eluate, and collect the eluate of the second elution in stages, then perform precipitation with oxalic acid, wash the precipitate with pure water, and then obtain high-purity rare earth oxide by calcining the precipitate at high temperature, the obtained rare earth oxide is praseodymium oxide, and the purity reaches 99.999%.

[0042] Example 3: A method for preparing high-purity rare earth by mixed elution ion exchange, which comprises the following steps:

[0043] (1) Ion exchange device preparation: Take several ion exchange columns and divide them into adsorption columns and separation columns, the number ratio of the adsorption columns and the separation columns is 1:6, fill the ion exchange resin into the adsorption columns and the separation columns respectively, the filling height is 100%; wash the adsorption columns and the separation columns with pure water respectively, then wash them with nitric acid solution respectively, convert them into H + type resin, then wash them with pure water to remove the excess nitric acid, and then wash them with ammonia solution to convert them into NH + type resin, then wash them with pure water to remove the excess ammonia; the length of the ion exchange column is 0.3 m, and the inner diameter is 1 cm; the ion exchange resin is strong acid styrene cation exchange resin, and the particle size of the ion exchange resin is 0.01 μm; the concentration of the nitric acid solution is 0.12 mol / L, and the concentration of the ammonia solution is 3 mol / L;

[0044] (2) Adsorption of rare earth ions by the adsorption column: take the adsorption column obtained by step (1), add the rare earth solution into the adsorption column, and then wash the excess rare earth solution in the adsorption column with pure water after the eluate becomes turbid when detected with oxalic acid solution; the rare earth solution is praseodymium chloride solution, and the concentration of the rare earth solution is 2 mol / L;

[0045] (3) Preparation of eluent: select ammonium acetate as eluent A, and select EDTA as eluent B; dissolve the eluent A in the ammonia solution to obtain the main eluent; add the eluent B into the main eluent and mix them uniformly to obtain the mixed eluent I; 0.08 mol of eluent A is contained in every 1 L of the main eluent; the volume of the mixed eluent I is 10.8 times the volume of the main eluent, and the amount of eluent B is 10 times the theoretical amount;

[0046] (4) Connect the adsorption column treated by step (2) and the separation column treated by step (1) end to end, and then perform elution, the elution process is as follows: add the mixed eluent I into the adsorption column to perform first elution, then add the main eluent to perform second elution, immediately start to collect the eluate when the eluate of the last separation column becomes turbid when detected with oxalic acid solution, and collect the eluate of the second elution in stages, then perform segmented precipitation with oxalic acid, wash the precipitate with pure water, and then obtain high-purity rare earth oxide by calcining the precipitate at high temperature, the obtained rare earth oxide is praseodymium oxide, and the purity reaches 99.999%.

[0047] Example 4: A method for preparing high-purity rare earth by mixed elution ion exchange method, which comprises the following steps:

[0048] (1) Ion exchange device preparation: take several ion exchange columns into adsorption column and separation column, the number ratio of the adsorption column and the separation column is 1:4, fill ion exchange resin into the adsorption column and the separation column respectively, the filling height is 90%; wash the adsorption column and the separation column with pure water respectively, then wash with nitric acid solution respectively, convert into H + type resin, then wash with pure water to remove excess nitric acid, and then wash with ammonia solution to convert into NH + type resin, then wash with pure water to remove excess ammonia; the length of the ion exchange column is 1.5 m, and the inner diameter is 10 cm; the ion exchange resin is weak acid styrene cation exchange resin, and the particle size of the ion exchange resin is 40 μm; the concentration of the nitric acid solution is 0.5 mol / L, and the concentration of the ammonia solution is 1 mol / L;

[0049] (2) Adsorption column adsorbs rare earth ions: take the adsorption column obtained by step (1), add rare earth solution into the adsorption column, and then wash the excess rare earth solution in the adsorption column with pure water when the eluate becomes turbid by detecting with oxalic acid aqueous solution; the rare earth solution is erbium nitrate solution, and the concentration of the rare earth solution is 0.1 mol / L; add a retarder into the separation column treated by step (1), and then wash the excess retarder with pure water when the eluate becomes blue, the retarder is obtained by mixing copper nitrate and nitric acid solution, the molar ratio of the copper nitrate and the nitric acid is 1:0.5, and the concentration of the copper nitrate in the retarder is 50 g / L;

[0050] (3) Preparation of eluent: select EDTA as eluent A and select ammonium acetate as eluent B; dissolve the eluent A in ammonia solution to obtain main eluent; add the eluent B into the main eluent to obtain mixed eluent I; 0.0015 mol of eluent A is contained in every 1 L of the main eluent; the volume of the mixed eluent I is 0.5 times of the volume of the main eluent, and the amount of the eluent B is 2 times of the theoretical amount;

[0051] (4) connect the adsorption column treated by step (2) and the separation column eluted with the retarder in series, and then elute, the elution process is as follows: add the main eluent to start the first elution from the adsorption column, then add the mixed eluent I to start the second elution, when the eluate of the last separation column changes from blue to transparent and becomes turbid by detecting with oxalic acid aqueous solution, immediately collect the eluate, and collect the eluate of the first elution and the second elution in stages, then carry out segmented precipitation with oxalic acid, wash the precipitate with pure water, and then calcine the precipitate at high temperature to obtain high-purity rare earth oxide, the obtained rare earth oxide is erbium oxide, and the purity reaches 99.999%.

[0052] Embodiment 5: A method for preparing high-purity rare earth by mixed elution ion exchange, comprising the following steps:

[0053] (1) Ion exchange device preparation: several ion exchange columns are divided into adsorption columns and separation columns, the number ratio of the adsorption columns and the separation columns is 1:4, ion exchange resin is filled into the adsorption columns and the separation columns respectively, the filling height is 88%; the adsorption columns and the separation columns are washed with pure water respectively, then they are washed with nitric acid solution respectively, converted into H + form resin, then washed with pure water to remove excess nitric acid, and then washed with ammonia solution to convert into NH + form resin, and then washed with pure water to remove excess ammonia; the length of the ion exchange column is 2 m, and the inner diameter is 15 cm; the ion exchange resin is strong acid styrene cation exchange resin, and the particle size of the ion exchange resin is 100 μm; the concentration of the nitric acid solution is 0.2 mol / L, and the concentration of the ammonia solution is 1.2 mol / L;

[0054] (2) Adsorption of rare earth ions by the adsorption column: the adsorption column obtained by step (1) is taken, and rare earth solution is added to the adsorption column, after the eluate becomes turbid when detected by oxalic acid aqueous solution, the excess rare earth solution in the adsorption column is washed away with pure water; the rare earth solution is gadolinium nitrate solution, and the concentration of the rare earth solution is 0.3 mol / L; a retarder is added to the separation column treated by step (1), after the eluate becomes blue, the excess retarder is washed away with pure water, the retarder is obtained by mixing copper nitrate and nitric acid solution, the molar ratio of the copper nitrate and the nitric acid is 1:0.5, and the concentration of the copper nitrate in the retarder is 50 g / L;

[0055] (3) Preparation of eluent: HEDTA is selected as eluent A, DTPA is selected as eluent B, and NTA is selected as eluent C; the eluent A is dissolved in ammonia solution to obtain main eluent; the eluent B is added to the main eluent to obtain mixed eluent I; the eluent C is added to the main eluent to obtain mixed eluent II; 0.05 mol of the eluent A is contained in every 1 L of the main eluent; the volume of the mixed eluent I is 0.05 times the volume of the main eluent, and the amount of the eluent B is 1.3 times the theoretical amount; the volume of the mixed eluent II is 0.4 times the volume of the main eluent, and the amount of the eluent C is 100 times the theoretical amount;

[0056] (4) connecting the adsorption column treated in step (2) and the separation column to which the delaying agent is eluted in series, and then performing elution, the elution process being that mixed eluent I is added to start the first elution, then main eluent is added to perform the second elution, and then mixed eluent II is added to perform the third elution, during the first elution, the second elution and the third elution, the eluate of the last separation column is taken immediately after the eluate changes from blue to transparent and becomes turbid when detected by oxalic acid aqueous solution, and the eluates of the second elution and the third elution are taken in stages, and then the precipitate is obtained by segmental precipitation with oxalic acid, and the precipitate is washed with pure water, and then the precipitate is calcined at high temperature to obtain high-purity rare earth oxide, and the obtained rare earth oxide is gadolinium oxide, and the purity reaches 99.99999%.

[0057] Example 6: a method for preparing high-purity rare earth by mixed elution ion exchange method, comprising the following steps:

[0058] (1) preparation of ion exchange device: a plurality of ion exchange columns are taken to be divided into adsorption columns and separation columns, the number ratio of the adsorption columns to the separation columns is 1:4, ion exchange resins are filled into the adsorption columns and the separation columns respectively, and the filling height is 90%; the adsorption columns and the separation columns are washed with pure water respectively, and then washed with nitric acid solution respectively to convert into H + type resin, and then washed with pure water to remove excess nitric acid, and then washed with ammonia solution to convert into NH + type resin, and then washed with pure water to remove excess ammonia; the length of the ion exchange column is 1.5 m, and the inner diameter is 10 cm; the ion exchange resin is weakly acidic styrene cation exchange resin, and the particle size of the ion exchange resin is 40 μm; the concentration of the nitric acid solution is 0.5 mol / L, and the concentration of the ammonia solution is 1 mol / L;

[0059] (2) adsorption of rare earth ions by the adsorption column: the adsorption column treated in step (1) is taken, and rare earth solution is added to the adsorption column, and then the eluate is detected by oxalic acid aqueous solution to become turbid, and then the excess rare earth solution in the adsorption column is washed away with pure water; the rare earth solution is ytterbium nitrate solution, and the concentration of the rare earth solution is 0.1 mol / L; the delaying agent is added to the separation column treated in step (1), and then the eluate becomes blue, and the excess delaying agent is washed away with pure water, the delaying agent is obtained by mixing copper nitrate and nitric acid solution, the molar ratio of the copper nitrate to the nitric acid is 1:0.5, and the concentration of the copper nitrate in the delaying agent is 50 g / L;

[0060] (3) preparation of the eluent: EDTA is selected as the eluent A, and ammonium acetate is selected as the eluent B; the eluent A is dissolved in an ammonia solution to obtain a main eluent; the eluent B is added to the main eluent to obtain a mixed eluent I; 0.0015 mol of the eluent A is contained in 1 L of the main eluent; the volume of the mixed eluent I is 0.5 times the volume of the main eluent, and the amount of the eluent B is 2 times the theoretical amount;

[0061] (4) the adsorption column treated in step (2) and the separation column for separating the eluent from the retarder are connected in series, and then elution is performed; the elution process is that the main eluent is added to the adsorption column to perform first elution, and then the mixed eluent I is added to perform second elution; during the first elution and the second elution, when the eluent of the last separation column changes from blue to transparent and becomes turbid when detected by an oxalic acid aqueous solution, the eluent is immediately collected; the eluent of the first elution and the second elution is collected in stages; then, the oxalic acid is used for segmental precipitation; after the precipitate is washed with pure water, the precipitate is calcined at high temperature to obtain high-purity rare earth oxide; the obtained rare earth oxide is ytterbium oxide, and the purity reaches 99.9999%.

[0062] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for producing high purity rare earths by a mixed elution ion exchange process, characterized by: The method comprises the following steps: (1) Ion exchange device preparation: take several ion exchange columns and divide them into adsorption columns and separation columns, the number ratio of the adsorption columns and the separation columns is 1:(2-6), fill ion exchange resin into the adsorption columns and the separation columns respectively, the filling height is 80-100%; wash the adsorption columns and the separation columns with pure water respectively, then wash them with hydrochloric acid solution or nitric acid solution respectively, convert them into H + type resin, then wash them with pure water to remove excess hydrochloric acid or nitric acid, and then wash them with ammonia water solution to convert them into NH + type resin, and then wash them with pure water to remove excess ammonia water; (2) adsorbing rare earth ions by the adsorption column: taking the adsorption column treated in step (1), adding a rare earth solution into the adsorption column, and washing the excess rare earth solution in the adsorption column with pure water after the eluate becomes turbid when detected by an oxalic acid aqueous solution; (3) preparation of eluent: selecting any one of citric acid, tartaric acid, HEDTA, EDTA, NTA, ammonium acetate, DCTA, DTPA, lactic acid and malic acid as eluent A or eluent B or eluent C, and the eluent A, eluent B and eluent C are all different; dissolving the eluent A in an ammonia water solution to obtain a main eluent; adding the eluent B into the main eluent and mixing to obtain a mixed eluent I; adding the eluent C into the main eluent and mixing to obtain a mixed eluent II; (4) connecting the adsorption column treated in step (2) and the separation column treated in step (1) in sequence, and then performing elution, and the elution process is any one of the following three process modes: the first process mode is adding the mixed eluent I into the adsorption column to perform first elution, then adding the main eluent to perform second elution, and immediately starting to collect the eluate when the eluate of the last separation column becomes turbid when detected by an oxalic acid aqueous solution, and collecting the eluate of the second elution in stages, and then performing segmented precipitation with oxalic acid, washing the precipitate with pure water, and calcining the precipitate at high temperature to obtain high-purity rare earth oxide; the second process mode is adding the main eluent into the adsorption column to perform first elution, then adding the mixed eluent I to perform second elution, and immediately starting to collect the eluate when the eluate of the last separation column becomes turbid when detected by an oxalic acid aqueous solution, and collecting the eluate of the first elution and the second elution in stages, and then performing segmented precipitation with oxalic acid, washing the precipitate with pure water, and calcining the precipitate at high temperature to obtain high-purity rare earth oxide; the third process mode is adding the mixed eluent I into the adsorption column to perform first elution, then adding the main eluent to perform second elution, and then adding the mixed eluent II to perform third elution, and immediately starting to collect the eluate when the eluate of the last separation column becomes turbid when detected by an oxalic acid aqueous solution, and collecting the eluate of the second elution and the third elution in stages, and then performing segmented precipitation with oxalic acid, washing the precipitate with pure water, and calcining the precipitate at high temperature to obtain high-purity rare earth oxide.

2. The method of claim 1, wherein the method is characterized by: The method comprises the following steps: The length of the ion exchange column is 0.3-3 m, and the inner diameter is 1-50 cm.

3. The method of claim 1, wherein the mixed-laden ion exchange method for producing high purity rare earths is characterized by: The ion exchange resin is any one of strong acid styrene cation resin and weak acid styrene cation resin, and the particle size of the ion exchange resin is 0.01-100 μm.

4. The method of claim 1, wherein the mixed elution ion exchange process is performed under the conditions of: The concentration of the hydrochloric acid solution is 0.01-5 mol / L, the concentration of the nitric acid solution is 0.12-5 mol / L, and the concentration of the ammonia water solution is 0.1-3 mol / L. ​ 5. The method of claim 1, wherein the mixed-laden ion exchange method for producing high purity rare earths is characterized by: The rare earth solution in step (2) is a rare earth chloride solution or a rare earth nitrate solution, and the concentration of the rare earth solution is 0.01-2 mol / L.

6. The method of claim 1, wherein the mixed-laden ion exchange method for producing high purity rare earths is characterized by: In step (3), 0.001-0.1 mol of the eluent A is contained in 1 L of the main eluent.

7. The method of claim 1, wherein the mixed-laden ion exchange method for producing high purity rare earths is characterized by: In step (3), the volume of the mixed eluent I is 0.001-1 times the volume of the main eluent, and the volume of the mixed eluent II is 0.001-1 times the volume of the main eluent.

8. The method of claim 1, wherein the method is characterized by: A retarder is added to the separation column treated in step (1), and after the eluate turns blue, the excess retarder is washed away with pure water. The retarder is obtained by mixing copper nitrate and nitric acid solution, the molar ratio of the copper nitrate to the nitric acid is 1: (0.1-1), and the concentration of the copper nitrate in the retarder is 50 g / L.

9. The method of claim 8, wherein the mixed-laden ion exchange method for producing high purity rare earths is characterized by: In step (4), the adsorption column treated in step (2) and the separation column eluted with the retarder are connected in series, and then elution is carried out. The elution process is any one of the following three process modes: In the first process mode, the mixed eluent I is added to the adsorption column to carry out first elution, and then the main eluent is added to carry out second elution. During the first elution and the second elution, when the eluate of the last separation column turns transparent from blue and becomes turbid when detected with an aqueous oxalic acid solution, the eluate is immediately collected, and the eluate of the second elution is collected in stages. Then, the eluate is precipitated in stages with oxalic acid, the precipitate is washed with pure water, and the precipitate is calcined at high temperature to obtain high-purity rare earth oxide. In the second process mode, the main eluent is added to the adsorption column to carry out first elution, and then the mixed eluent I is added to carry out second elution. During the first elution and the second elution, when the eluate of the last separation column turns transparent from blue and becomes turbid when detected with an aqueous oxalic acid solution, the eluate is immediately collected, and the eluate of the first elution and the second elution is collected in stages. Then, the eluate is precipitated in stages with oxalic acid, the precipitate is washed with pure water, and the precipitate is calcined at high temperature to obtain high-purity rare earth oxide. In the third process mode, the mixed eluent I is added to the adsorption column to carry out first elution, the main eluent is then added to carry out second elution, and the mixed eluent II is added to carry out third elution. During the first elution, the second elution and the third elution, when the eluate of the last separation column turns transparent from blue and becomes turbid when detected with an aqueous oxalic acid solution, the eluate is immediately collected, and the eluate of the second elution and the third elution is collected in stages. Then, the eluate is precipitated in stages with oxalic acid, the precipitate is washed with pure water, and the precipitate is calcined at high temperature to obtain high-purity rare earth oxide.

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