JPH0725543B2 - Rare earth element separation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of separating and refining and recovering a rare earth element having high economic efficiency by an ion exchange method, and more specifically, forming a complex with a strongly acidic cation exchange resin. The agent is used to obtain a high recovery of high-purity yttrium from a mixture of rare earth elements, and the complexing agent relates to a highly economical process of recycling.

Rare earth elements are a general term for lanthanide group elements, scandium (Sc) and yttrium (Y), and are widely used in fluorescent materials, permanent magnet materials, ceramic strength enhancers, catalysts, magnetic recording materials, hydrogen storage materials, etc. It is a useful element that is expected to grow greatly in demand.

[Problems to be Solved by Prior Art and Invention] Among the ion exchange methods, the most widely known method is, for example,
A mixed solution of salts of rare earth elements is passed through a packed bed of strong acid cation exchange resin to form an adsorption zone of rare earth on the upper part of the strong acid cation exchange resin bed, followed by washing with water. Next, by flowing the complexing agent solution and utilizing the slight difference in affinity between each rare earth element and the complexing agent and the ion exchange resin,
This is a method of performing chromatographic separation to obtain highly pure rare earth elements.

In this method, copper (II) ions, iron (III) ions, nickel (I
I) Metal ions such as ions are used, and there is a risk that these metal ions may be mixed with the rare earth element, so that high purification is difficult. Further, it is essential to collect and reuse these metal ions, which complicates the operation and the device for that purpose.

In the ion exchange method, the concentration of the complex-forming agent is close, the amount of the complex-forming agent aqueous solution used and the aqueous solution (eluate) of the rare-earth element and the complex-forming agent obtained by separation are huge, and the rare-earth element of the eluate is very large. The element concentration is extremely low. Therefore,
The device becomes larger. Further, it is necessary to separate the rare earth element and the complexing agent from a huge amount of eluate.

Conventionally, for example, the complexing agent is ethylenediaminetetraacetic acid (EDT
In the case of A), as a method for separately collecting EDTA and rare earth elements from the obtained eluate containing rare earth elements and EDTA,
First, mineral acid is added to the eluate to convert EDTA into an acid form to precipitate as a precipitate, which is washed and filtered to recover EDTA, and then
A method is generally used in which an insoluble rare earth salt is precipitated by adding oxalic acid or the like to a liquid and washed, dried, dried, and fired to form a rare earth oxide. However, when such a method is carried out on an industrial scale, EDTA must be separated and separated from a large amount of eluate, which complicates the operation and enlarges the apparatus. Also,
The EDTA dissolved in the liquid is purged out of the system as it is, resulting in loss. That is, it is disadvantageous technically and economically.

Since the concentration of rare earth elements in the liquid is extremely low and the amount is large, the operation is complicated and the device becomes large. In addition, the efficiency of over-cleaning is very poor and the recovery rate of rare earth elements is low.

Has technical and economic problems.

Further, the complexing agent is N-hydroxyethylethylenediamine triacetic acid (HEDTA), diethylenetriamine-N, N, N ',
When the solubility in acid form such as N ″, N ″ -pentaacetic acid (DTPA) is large, oxalic acid is directly added to the eluate to precipitate the oxalate salt of the rare earth element, and the rare earth element is washed, dried, dried, and calcined. On the other hand, there is a method in which an elemental oxide is used, and on the other hand, the solution is reused after adjusting the pH, or hydrogen peroxide is added to decompose excess oxalic acid to adjust the pH and then reuse.

In this method, since rare earth elements are precipitated and recovered from a large amount of eluate, the operation is complicated and the apparatus becomes large. Since rare earth elements and oxalic acid often remain in the liquid, there is a possibility that the mutual decomposition property of the rare earth elements may be deteriorated during reuse and the residual oxalic acid may cause precipitation of the rare earth elements in the column. Further, since the rare earth element is precipitated and recovered in the presence of the complex forming agent, the recovery rate of the rare earth element is lowered. Furthermore, the method of decomposing oxalic acid by adding hydrogen peroxide has many and serious problems such as increase in drug cost.

JP-A-58-41719 uses two kinds of complexing agents,
A method for purifying yttrium by separating it with a cation exchange resin three times is disclosed.

With this method, high purity yttrium can be obtained,
Also, the complexing agent can be recovered and reused.

However, the high-purity yttrium fraction obtained by the method has a low yttrium concentration and contains EDTA.
Therefore, in order to recover yttrium, it is necessary to first add an acid to precipitate and separate EDTA, and then to precipitate yttrium as a sparingly soluble salt from a low-concentration yttrium aqueous solution with oxalic acid or ammonia and to recover it. Therefore,
The operation is complicated, the apparatus becomes large, and yttrium is excessively recovered from the low-concentration yttrium aqueous solution, so that the recovery rate is reduced and the purity of yttrium is reduced due to the inclusion of impurities from water and chemicals.

Further, in this method, there is no distinction between an adsorption column and a separation column, and therefore the optimum counter ion of the cation exchange resin cannot be selected in each column, and improvement in separation and purification cannot be expected.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems of the prior art, and uses a strongly acidic cation exchange resin and a complexing agent to produce high-purity yttrium at a high recovery rate. An object of the present invention is to provide a highly economical method for separating rare earth elements which can be recycled without loss of a complexing agent.

The present inventors have found out a method for separating rare earth elements by an ion exchange method, in which high-purity yttrium can be obtained from a mixture of rare earth elements at a high recovery rate and can be reused without loss of a complex-forming agent. I studied as much as possible.

[Means for Solving Problems] As a result, a highly acidic cation exchange resin was used as the ion exchanger, the ion exchange column was divided into an adsorption column and a separation column, and adsorption and separation operations were performed twice to achieve high purity. The yttrium fractionated solution can be obtained, and an aqueous solution of a rare earth element and a complexing agent can be adsorbed with a rare earth element by passing through an adsorption tower, and an aqueous solution of a complexing agent containing substantially no rare earth element can be obtained. And by passing the high-purity yttrium fraction solution through the adsorption tower in the same manner, high-purity yttrium can be adsorbed, and an aqueous solution of a complexing agent substantially free of yttrium can be obtained, and the adsorbed high-purity yttrium is an acid aqueous solution. They found that they can be attached and detached, and finally assembled the above findings to complete the present invention.

That is, the present invention relates to a method for separating, purifying and recovering yttrium from a rare earth element mixture using a complexing agent and a strong acid cation exchange resin. Is passed through the adsorption tower A to adsorb the rare earth element, the adsorbed liquid is discharged from the adsorption tower A, and (b) the adsorption tower A and the strongly acidic cation exchange resin are filled. The separation tower A is connected to the adsorption tower A to separate the rare earth elements from each other through the aqueous solution of the complexing agent A to obtain a rare earth element fraction containing yttrium as a main component. (C) The fraction is strongly acidic An aqueous solution of the complex-forming agent A containing substantially no rare earth element by passing through the adsorption tower B filled with a cation exchange resin to adsorb the rare earth element and discharging the liquid after the adsorption treatment from the adsorption tower B. (D) Strong adsorption of cation with the adsorption tower B The separation tower B filled with a resin is connected, and the rare earth elements are mutually separated from the adsorption tower B through the aqueous solution of the complex forming agent B to obtain an yttrium fractionation solution. (E) The yttrium fractionation solution is a strongly acidic cation. The solution is passed through an adsorption tower C filled with an exchange resin to adsorb yttrium, and an aqueous solution of the complex-forming agent B substantially free of yttrium is recovered, and (f) an acid aqueous solution is passed through the adsorption tower C to recover yttrium. The gist is a method for separating rare earth elements, which is characterized in that.

According to the present invention, high-purity yttrium can be obtained in a high yield from a mixture of rare earth elements, and an expensive complexing agent can be recycled and used without loss. Further, the operation is easy, the apparatus can be made compact, and high economy can be achieved.

Hereinafter, the present invention will be described in more detail.

In the present invention, an aqueous solution of a mixture of rare earth elements containing yttrium (Y) is passed through an adsorption tower A filled with a strongly acidic cation exchange resin to adsorb the rare earth elements.

There is no particular limitation on the aqueous solution of the mixture of rare earth elements containing Y. For example, an aqueous solution obtained by separating and dissolving ores such as xenotime, monazite, and bastnasite with an alkali such as mineral acid or caustic soda, or an extraction method from these aqueous solutions,
Examples thereof include an aqueous solution in which an oxide or hydroxide of a rare earth element obtained by crude purification by a crystallization method or the like is dissolved with a mineral acid.

The pH of the aqueous solution is preferably 0.5 to 4, and more preferably 1.0 to 3.0. If the pH is too low, the adsorption rate of rare earth elements decreases. Conversely, if it is too high, hydroxides of rare earth elements will be deposited.

There is no problem if the concentration of the rare earth element is equal to or lower than the concentration at which it dissolves, but if it is too low, the liquid amount increases. Concentration is 0.01 to 2 mol
/ l is preferable. The temperature may be 40 to 120 ° C, which is handled as usual. The liquid passing speed to the adsorption tower A is SV (superficial tower speed) 0.1-1.
0Hr ^-1 is preferred. If it is too low, it will take a long time, and if it is too high, rare earth elements may flow out without being adsorbed.

The strongly acidic cation exchange resin packed in the adsorption tower A has a sulfonic acid group as an exchange group, and as a resin consisting only of a sulfonic acid group, commercially available Organo Corporation Amberlite CG-120, Amberlite is used. IR-120B, Amberlite IR-252; Mitsubishi Kasei Co., Ltd. Diaion SK1
B, Diaion RMK-80S, Diaion PK216; Dowex 50W, Dowex 88 and the like manufactured by Dow Chemical Co. The smaller the particle size of the resin, the higher the adsorption rate, which is preferable, but when it is too small, the pressure loss increases. The preferred resin diameter is 0.05 to 0.3 mm. Further, the exchange group may be a mixed type of sulfonic acid group and weak acid group such as carboxylic acid group, phenolic acid group and phosphoric acid group. Adsorption of rare earth elements does not change even in the mixed type. Rather, it is desirable because it improves the mutual separability of the rare earth elements by the aqueous solution of the complexing agent A which will be described later. The ratio of the exchange capacity of the sulfonic acid group to the weak acid group is preferably 1.0 or more. Specific examples of the mixed type are disclosed in JP-A-53-4787,
An ion exchange fiber composed of a sulfonic acid group and a carboxylic acid group, which is disclosed in JP-A-58-45341, can be mentioned. The ion exchange fiber preferably has a length of 0.01 to 1 mm and a diameter of 0.005 to 0.1 mm so that the liquid passing rate can be increased.

Proton (H ⁺ ) and / or ammonium ion (MH ₄ ⁺ ) is preferable as the counter ion of the exchange group of the strongly acidic cation exchange resin, and the adsorption of rare earth elements is good, and the mutual separation property of the rare earth elements afterwards is improved. To do. This can be achieved by passing an aqueous solution of acid, an aqueous solution of ammonium salt, or a mixed aqueous solution of ammonium salt and ammonia through the column. Further, when the counter ion is NH ₄ ⁺ , the mutual separability of rare earth elements is further improved, which is more preferable. At this time, the weak acid group may be H ⁺ .

The amount of the rare earth element-mixed aqueous solution containing Y that is passed through the adsorption tower A is preferably 0.5 to 0.95 equivalent times the total ion exchange capacity of the sulfonic acid groups of the strongly acidic cation exchange resin. When it is low, a large amount of resin is required, and when it is high, a part of the rare earth element flows out. Packed bed height (Z) with respect to the inner diameter (D) of the adsorption tower A
Is preferably 2 to 50, more preferably 3 to 50, since it enhances the adsorption efficiency of rare earth elements and facilitates the production of adsorption towers.
30 is preferred.

Here, part of the counter ion of the sulfonic acid group of the resin is changed to H ⁺ by the acid of the aqueous solution of the rare earth element. In this case, it is desirable to pass an ammonium salt aqueous solution of 0.01 to 1 eq / l in an amount of 0.5 to 5 equivalents with respect to the acid of the rare earth element aqueous solution so that the counter ion is N
Set to H ₄ ⁺ .

Also, the adsorption tower A is washed with pure water before proceeding to the next operation.

Next, the adsorption tower A and the separation tower B filled with a strongly acidic cation exchange resin are connected to separate the rare earth element from the adsorption tower A through the aqueous solution of the complex forming agent A, and the rare earth element containing Y as a main component is separated. Obtain a fraction.

As the strongly acidic cation exchange resin in the separation tower A, the same resin as in the adsorption tower A can be used. However, in order to improve the mutual separability of rare earth elements, the above ion exchange fiber composed of a sulfonic acid group and a carboxylic acid group is particularly preferable. When ion-exchange fibers are used, the liquid passing rate can be increased and mutual separability can be improved. Further, the counter ion of the ion exchange groups are H ⁺ and / or NH ₄ ⁺ is good, it is particularly preferred counterion of the sulfonic acid group is NH ₄ ^+. Conversion to these counter ions can be carried out by the same operation as described above.
As will be described later, when the counter ion of the complexing agent A is NH ₄ ⁺ ,
The counterion of the resin after separation is NH ₄ ⁺ , and the separation operation may be repeated as it is without converting the type. According to this method, the drug cost and the operation time can be shortened.

As the amount of resin in the separation tower A increases, the mutual separability of rare earth elements improves, but on the other hand, the cost of the resin increases and the concentration of the rare earth elements to be eluted decreases. The preferred amount of resin is such that the total sulfonic acid group of the resin is 0.1 to the adsorbed rare earth element.
The amount is 0.5 equivalent times. Also, the ratio of the height (Z) of the packed bed to the inner diameter (D) of the tower is preferably 2 to 50 in order to enhance the mutual separability of rare earth elements and the easiness of operation of the tower.
-40 are more preferred. The separation column A is usually larger than the adsorption column A. In the present invention, since the adsorption tower A and the separation tower A are separately provided, D of the separation tower A can be set without being restricted by D of the adsorption tower A.

The complexing agent A is usually used for mutual separation of rare earth elements, and includes ethylenediaminetetraacetic acid (EDTA), N-
Hydroxyethyl ethylenediamine triacetic acid (HEDTA), 1,
2-diaminocyclohexanepentaacetic acid (DCPA), diethylenetriamine-N, N, N ', N ", N" -pentaacetic acid (DTPA), ethylene glycol-bis (2-aminoethyl) ether-N, N, N', N'-tetraacetic acid (DE), bis (2-aminoethyl) ether-N, N, N ', N'-tetraacetic acid (ME), nitrilotriacetic acid (NTA), iminodiacetic acid (IMPA) Acetic acids; oxycarboxylic acids such as citric acid, lactic acid, glycolic acid, malic acid, tartaric acid and the like can be used, or they may be mixed and used. In particular, aminopolyacetic acids are preferable because they are excellent in mutual separability of rare earth elements.
Furthermore, EDTA is more preferable because it has a good mutual separation property for most rare earth elements, is easily available, and is relatively inexpensive.

The concentration of the complexing agent A is below the saturated solubility and is 5 to 100 m.
mol / l is preferred. When it is low, a large amount of aqueous solution of the complex forming agent A is handled, and when it is high, the mutual separability of rare earth elements deteriorates. The pH of the aqueous solution is preferably 3 to 11, which is usually used, and preferably 4 to 8. Further, the cation of the aqueous solution of the complex forming agent A is preferably H ⁺ and / or NH ₄ ⁺ . In this case, not only the mutual separability of rare earth elements is improved, but also high purity yttrium can be obtained.

The rate at which the aqueous solution of the complex-forming agent A is passed is preferably SV0.1 to 3 Hr ⁻¹ with respect to the total amount of resin in the adsorption tower A and the separation tower A.
If it is small, the mutual separability is improved, but the separation takes a long time, and if it is large, the mutual separability is deteriorated. The use of in-exchange fibers is preferable because this speed can be increased.

The temperature during liquid passage is 30 to 120 ° C, preferably 50 to 95
℃.

The rare earth elements adsorbed by the aqueous solution of the complex forming agent A are eluted and separated from each other. The order of the rare earth elements to be eluted is determined by the complex formation constant of the complex forming agent A and the rare earth element, and the rare earth elements having a larger complex formation constant are eluted in order. When EDTA is used, it is eluted from the rare earth element (heavy rare earth element) having a large atomic number. Then, Y elutes in almost the same order as dysprosium (Dy), and thus a fractionated solution of Y containing Dy is obtained.

When HEDTA and DTPA are used as the complexing agent A, Y is eluted in almost the same order as neodymium (Nd) to obtain a Y fraction containing Nd. It is difficult to obtain a pure Y fraction even if other complexing agents are used.

Therefore, in the present invention, a rare earth element fraction containing Y as a main component is sent to the next step in order to obtain high purity Y.

On the other hand, other than the fractionated liquid containing Y as the main component, other rare earth element fractionated liquids can be obtained at the same time. If the fractionated liquid has good purity, the rare earth element can be recovered by the same operation as the operation using the adsorption tower C. If the purity is insufficient, the rare earth element can be recovered by performing the same operation as the operation using the adsorption tower B, the separation tower B and the adsorption tower C. Therefore, the method of the present invention can obtain rare earth elements other than Y with high purity and high recovery rate.

Next, the rare earth element fraction containing Y as a main component is passed through an adsorption tower B filled with a strongly acidic cation exchange resin to adsorb the rare earth element, and the complex forming agent A containing substantially no rare earth element.
The aqueous solution of is collected.

The purpose of this step is to adsorb the rare earth element containing Y as the main component from the rare earth element fraction containing Y as the main component in the adsorption tower B to obtain an aqueous solution of the complex-forming agent A containing substantially no rare earth element. At the same time, when eluting with the complexing agent B in the next step, the operation is performed so as to enhance the mutual separability of the rare earth element containing Y as the main component.

As the strongly acidic cation exchange resin packed in the adsorption tower B, the same resin as that used in the adsorption tower A can be used. However, it preferably comprises the sulfonic acid groups mentioned above. Particle size 0.05
The resin is up to 0.3 mm, and the adsorption amount of the rare earth element containing Y as a main component can be increased. The resin has a gel type and a macroporous type. A macroporous type, which has a large physical strength and a good mutual separation property of rare earth elements in the next step, is more preferable. When ion-exchange fibers are used, the mutual separability of rare earth elements is improved, but the adsorbed amount of rare earth elements decreases, so the amount used must be increased.

The counter ion of the exchange group of the resin is preferably H ⁺ . When it is H ⁺ , the adsorption amount of the rare earth element can be increased.
When it is NH ₄ ⁺ , the amount of adsorption decreases due to the influence of the complexing agent A.

The pH of the rare earth element fraction containing Y as a main component is usually 2 to 5. When an acid is added to the fractionated solution to lower the pH, counter ions are added to NH ₄ ⁺
Even so, the adsorption amount can be increased. When it is H ⁺ , the adsorption amount can be further increased. The amount of acid added is preferably such that the pH of the fractionated solution becomes 1 to 4, particularly preferably 1 to 2.

When complexing agent A is EDTA and acid is added to lower the temperature, ED
Part of TA precipitates. You may separate this precipitation EDTA and pass the obtained liquid through the adsorption tower B. The amount of EDTA deposited varies depending on the amount of acid added, temperature, time and the like.

The flow rate of the fractionated solution is preferably SV 0.1 to 10 Hr ^-1 . The temperature during the passage is 30 to 120 ° C, preferably 50 to 95 ° C. When the temperature is high, the adsorption amount of rare earth element can be increased. However, the deterioration of the resin becomes severe and a large amount of heat energy is required. When the temperature is low, the deterioration of the resin is suppressed, but the adsorption amount of the rare earth element is reduced.

On the other hand, the aqueous solution of the complex-forming agent B containing substantially no rare earth element is eluted from the adsorption tower B. The term "substantially" as used herein means that the content of the aqueous solution of the complexing agent A obtained even if it contains a rare earth element is such that reuse does not hinder practical use. As long as adsorption is stopped at the breakthrough point, 1 mg / l or less,
It is usually maintained at 0.1 mg / l or less and can be reused sufficiently.

When the fractionated liquid of the rare earth element containing Y as the main component is passed through the adsorption tower B, first, the complex-forming agent A having a low concentration of the complex-forming agent A is obtained.
Depending on the type, a substantially nonexistent aqueous solution flows out. At this time, the complex forming agent A is adsorbed on the resin.
Therefore, by discharging the aqueous solution to the outside of the system, impurities mainly including anions can be purged. When the liquid flow is further continued, the complex forming agent A that has been adsorbed is desorbed, and as a result, the concentrated aqueous solution flows out. The concentration factor may reach twice. Thereafter, the adsorption of the rare earth element reaches saturation, and the aqueous solution of the complex forming agent A contains the rare earth element. The liquid passing operation ends at the same time as or before the breakthrough. The breakthrough can be easily detected by analyzing the aqueous solution of the complex forming agent A with an inductively coupled plasma emission spectroscopic analyzer, an atomic absorption spectrometer, a fluorescent X-ray analyzer, or the like.

The adsorption amount of rare earth element depends on the type of resin, temperature, and pH of the fractionation liquid.
Although it varies depending on the conditions, etc., it is usually 30 to 90% of the total ion exchange capacity of the sulfonic acid group of the adsorption tower B.

The obtained aqueous solution of the complex-forming agent A containing substantially no rare earth element may be circulated and reused as it is in the adsorption tower A. If necessary, the pH may be adjusted with aqueous ammonia, or the concentration may be adjusted with pure water. You may reuse it.

In this way, the complexing agent A can be almost recovered, but it is partially adsorbed on the resin. It can be removed and recovered by washing with water. After washing with water, the solution is passed through the following complexing agent B, but before that, with 0.01 to 1 eq / l ammonium salt aqueous solution,
It is preferable that the counter ion H ⁺ remaining in the adsorption tower B be NH ₄ ⁺ . By using NH ₄ ⁺ , mutual separability is improved and high purity Y can be obtained. The Z / D of the adsorption tower B is the same as that of the adsorption tower A.

Next, the adsorption tower B and the separation tower B filled with a strongly acidic cation exchange resin are connected to each other, and the rare earth elements are separated from each other through the aqueous solution of the complex forming agent B from the adsorption tower B to obtain the fractionated solution of Y.

The purpose of this step is to separate the rare earth elements containing Y as a main component adsorbed in the adsorption tower B from each other with an aqueous solution of the complexing agent B to obtain a high-purity Y fraction.

The kind and amount of the strongly acidic cation exchange resin packed in the separation column B and the counterion of the ion exchange group of the resin are the same as those in the separation column A. Also, the Z / D of the separation tower B, the temperature at the time of liquid passage, and the liquid passage speed may be the same as those of the separation tower A.

The complexing agent B may be the same as the complexing agent A,
From the viewpoint of efficiently obtaining a high-purity Y fraction, the complexing agent A
When is EDTA, the complexing agent B is preferably HEDTA or DTPA. When complexing agent A is HEDTA or DTPA, complexing agent B is preferably EDTA. That is, it is preferable to select the complexing agents A and B so that the elution order of Y is different. The concentration, pH and cation of the complexing agent B aqueous solution are the same as those of the complexing agent A aqueous solution.

By passing the aqueous solution of the complex forming agent B, the adsorbed rare earth element containing Y as a main component is eluted and separated from each other. In this way, a high-purity Y fraction can be obtained. Complexing agent A is EDTA and complexing agent B is HEDTA or D
When it is TPA, the Y fraction is obtained from the separation column B next to the Dy fraction.

On the other hand, fractions other than the Y fraction can be obtained. The fraction is
If the purity is good, the rare earth element can be recovered by the same operation as the operation using the adsorption tower C. If the purity is insufficient, the rare earth element can be recovered by performing the same operation as the operation using the adsorption tower B, the separation tower B and the adsorption tower C.

Next, the Y fraction is passed through an adsorption tower C filled with a strongly acidic cation exchange resin to adsorb Y, and an aqueous solution of the complex forming agent B containing substantially no Y is recovered.

The type and amount of the strongly acidic cation exchange resin packed in the adsorption tower C and the counterion of the ion exchange group of the resin are the same as those in the adsorption tower B. Also, the Z / D of the adsorption tower C, the temperature at the time of passing the liquid, and the passing speed can be the same as those of the adsorption tower B.

The pH of the Y fraction is usually 2-5. When an acid is added to the Y fraction to lower the pH, the amount of adsorption can be increased even if the counter ion is NH ₄ ⁺ . The amount of acid added is preferably such that the pH of the Y fractionation solution becomes 1 to 4, and particularly preferably 1 to 2. Complexing agent B
In the case of EDTA, if acid is added to lower the temperature, part of EDTA will precipitate. The liquid containing the precipitated EDTA may be passed through the adsorption tower C.

The amount of EDTA deposited varies depending on the amount of acid added, temperature, time and the like.

When the Y fraction is passed through, an aqueous solution of the complex forming agent B containing substantially no Y is obtained. The concentration, the amount of Y adsorbed, and the amount of liquid passing can be adjusted in the same manner as the adsorption operation using the adsorption tower B.

Further, in the present invention, the yttrium fractionation liquid from the separation column B may be passed through the adsorption column B again and the same operation may be performed thereafter. In this case, a highly pure yttrium fractionated liquid can be obtained.

Then, the aqueous acid solution is passed through the adsorption tower C to recover Y. The acid used may be either an organic acid or an inorganic acid, but an inorganic acid is preferable and the adsorbed Y can be recovered at a high rate. As the inorganic acid, one or more selected from hydrochloric acid, sulfuric acid, and nitric acid is desirable, and the recovery rate of Y can be increased by using a small amount of acid. The higher the acid concentration, the higher the recovery rate and the higher the concentration of the Y solution.
The acid concentration is preferably 1 N or higher, particularly preferably 3 N or higher. However, if it is too high, the swelling and contraction of the ion-exchange resin will become severe and the ion-exchange resin may be destroyed in some cases. Therefore, the preferable range is 1 to 10 N, and the more preferable range is 3 to 8 N. The amount of aqueous solution of acid used is 1/10 or less of the amount of eluate, provided that the amount of acid is equal to or more than the equivalent of adsorbed Y, and the acid concentration is 3 N or more to increase the concentration factor of rare earth elements. You can do it 10 times more easily.

The lower the temperature, the more effective the recovery rate can be improved. However, if it is too low, the heat energy loss increases. The temperature is preferably 20 to 95 ° C, more preferably 30 to 65 ° C. The temperature during desorption is preferably lower than the temperature during adsorption of Y. By making the temperature difference, the recovery rate of Y can be increased.

The aqueous acid solution may be circulated and used. This is preferable because it is possible to obtain a rare earth element aqueous solution having a higher concentration. That is, the aqueous solution of acid is circulated between the recovery tank and the recovery tower, and after the concentration reaches equilibrium, the circulation is stopped and the amount of the circulating liquid corresponding to the recovered rare earth element is extracted. Also in this case, the acid concentration of the circulating fluid should be 1 to 10 N, and further 3 to
8 rules are preferred. Next, the circulating fluid is supplemented with acid to prepare for the next recovery. According to this method, the concentration ratio of Y can be increased to 20 times or more and 100 times or more.

Further, it is not necessary to completely desorb Y from the strongly acidic cation exchange resin. In many cases, some of the rare earth elements remain undesorbed. However, the remaining Y does not flow out even when a new aqueous solution containing Y and the complex forming agent is passed through.
However, if the amount of residual adsorption is too large, the amount of treatment liquid will decrease. Therefore, the amount of residual adsorption is preferably 50% or less of the ion exchange capacity.

The counter ion of the strongly acidic cation exchange resin after recovering Y with the aqueous solution of acid is H ⁺ , and the aqueous solution containing Y and the complexing agent can be passed immediately after washing with water. When the acid solution is circulated and desorbed, the liquid may be passed in either direction. On the other hand, when the aqueous acid solution is passed through temporarily, it is preferable to pass the aqueous solution containing Y and the complex forming agent from the opposite direction.
The adsorption amount of Y can be increased. The solution used for washing with water may be used as a part of the aqueous solution of the acid for removing Y.

The concentrated solution of Y thus obtained is usually
It is 0.02 to 1 mol / l, and after neutralizing an excess acid with an alkali such as ammonia, oxalic acid, ammonia, etc. are added to form an insoluble precipitate, which can be excessively recovered. In this case, the excess is extremely easy, and the recovery rate of the rare earth element can be easily increased to 97% or more and 99% or more. These are also features of the method of the present invention.

After that, high purity yttrium oxide can be obtained by washing with water, drying and baking.

In addition, a rare earth element fraction liquid other than Y can be adsorbed and desorbed by an acid aqueous solution by the same operation, and a high purity and high concentration rare earth element solution can be obtained with a high recovery rate.

[Effects of the Invention] Next, the effects of the present invention will be listed.

According to the present invention, highly pure yttrium can be obtained with a high recovery rate from a mixture of rare earth elements.

The rare earth element and the complex-forming agent can be separated and recovered almost completely, the loss of the expensive chemical is almost eliminated, and the recovered aqueous solution of the complex-forming agent can be recycled and reused.

Yttrium can be recovered as a concentrated liquid,
Therefore, a device for precipitating and collecting yttrium from the concentrated liquid can be made compact, and the yttrium recovery rate can be increased.

Complexing agents, which have been difficult to recover due to their high solubility in acids such as HEDTA and DTPA, can be easily recovered and reused.

Rare earth elements other than yttrium can be isolated and highly purified by the same operation.

By dividing the column into an adsorption column and a separation column, the optimum conditions for adsorption and separation can be selected, and the yttrium separation and purification and recovery efficiency are improved. Further, the shapes of the adsorption tower and the separation tower can be economically set.

Furthermore, by purging the initial aqueous solution having a low concentration of the complexing agent flowing out from the adsorption towers B and C, the anion impurities can be purged, and the yttrium can be highly purified.

As described above, the present invention is a technically and economically highly efficient method.

[Examples] Examples of the present invention will be shown below, but the present invention is not limited thereto.

In addition,% is based on weight.

Example 1 Amberlite CG-120 having an inner diameter of 100 mm and a length of 1,000 mm and adsorption towers B and C with a filter were filled with Amberlite CG-120 whose ion-exchange group consisted of only sulfonic acid groups, and an inner diameter of 100 mm and a length
The adsorption tower A with a jacket and filter of 1,000 mm and the separation tower A and B with an inner diameter of 150 mm and a length of 2,000 mm and a separation tower A and B with a length of 250 μ and a sulfonic acid group of 2.6 me
Ion-exchange fibers with q / g and carboxylic acid groups of 1.0 meq / g were filled.

The adsorption tower A and the separation towers A and B are 1N-HCl and 1N-N
After conditioning with H ₄ Cl, the counter ion of the sulfonic acid group was NH ₄ ⁺ . In the adsorption towers B and C, the counter ion was H ⁺ with 1N-HCl.

Next, mixed oxides of rare earth elements (composition Y ₂ O ₃ : 61.9%, Er ₂
O ₃ : 4.4%, DyO: 7.1%, Gd ₂ O ₃ : 4.8%, Sm ₂ O ₃ : 2.3%, Yb ₂ O
₍₃ : 3.8%, other rare earth oxides: 8.9%) is dissolved in hydrochloric acid to make the concentration of rare earth elements 1.3 mol / l, pH 1.2, and the adsorption tower A at SV (superficial velocity) 5Hr ^-1 , 60 ° C. And then washed with water. The adsorption amount of the rare earth element in the adsorption tower A was 85% of the total ion exchange capacity of the sulfonic acid group, and the rare earth element did not break through.

Next, the adsorption tower A and the separation tower A were connected to each other, and while maintaining the temperature at 60 ° C, 0.75% EDTA aqueous solution of pH 5 was passed through the adsorption tower A with SV1.0Hr ^-1 to separate the rare earth elements from each other. Of the eluates from the separation column A, a fraction liquid containing Y as a main component (including Dy) was collected. Y of the fraction solution was 95% of the raw material.

The fraction liquid containing Y as a main component was heated to 80 ° C. and passed through the adsorption tower B. EDTA containing no rare earth elements (0.1 mg / l or less)
Effluent was obtained, and the recovery rate of EDTA was 95%, and the EDTA that had been adsorbed and adhered was recovered by washing with water, and the total recovery rate was almost 100%.

Next, the adsorption tower B and the separation tower B were connected and maintained at 60 ° C.
A 0.75% HEDTA aqueous solution having a pH of 7 was passed through the adsorption tower B with SV1.0Hr ⁻¹ to separate Y from other rare earth elements. Of the eluate from the separation column B, high purity Y having a purity of 99.99% or more
Fractions were collected. Y of the fraction solution was 91% of Y adsorbed on the adsorption tower B. The high-purity Y fraction solution was heated to 80 ° C. and passed through the adsorption tower C. An eluate of HEDTA containing no Y (0.1 mg / l or less) was obtained, and the HEDTA recovery rate was 91%. The remaining HEDTA could be almost completely recovered by washing the adsorption tower C with water.

Next, while maintaining the adsorption tower C at 30 ° C., 5N-HCl was added to SV3.0Hr.
^The solution was circulated for 2 hours at ^-1 to obtain a highly purified Y solution having a Y concentration of 10.2 g / l and concentrated 20 times and having a purity of 99.99% or more. Precipitation recovery with oxalic acid from the solution was extremely easy, and the precipitation recovery rate was 98.5% by using 1.5 equivalent times oxalic acid with respect to Y.
And the precipitate was dried and calcined to give a purity of 99.9.
High purity Y ₂ O ₃ of 9% or more was obtained.

Claims (6)

[Claims] 1. A method for separating, purifying and recovering yttrium from a mixture of rare earth elements by using a complexing agent and a strongly acidic cation exchange resin, wherein (a) an aqueous solution of the mixture is strongly acidic cation exchanged. The rare earth element is adsorbed by passing through the adsorption tower A filled with a resin, the adsorption-treated liquid is discharged from the adsorption tower A, and (b) the adsorption tower A and a strongly acidic cation exchange resin are filled. Rare earth elements are separated from each other through an aqueous solution of the complexing agent A from the adsorption tower A to obtain a rare earth element fraction containing yttrium as a main component, and (c) the fraction containing the strong acid. Is passed through an adsorption tower B filled with a water-soluble cation exchange resin to adsorb the rare earth element, and the adsorbed liquid is discharged from the adsorption tower B to produce a complex forming agent A containing substantially no rare earth element. (D) The adsorption tower B and strong acid cation exchange are recovered. A rare earth element is separated from each other through an aqueous solution of the complexing agent B from the adsorption tower B by connecting to a separation column B filled with a replacement resin, and an yttrium fraction is obtained. (E) The yttrium fraction is strongly acidic and positive. The solution is passed through an adsorption tower C filled with an ion exchange resin to adsorb yttrium, and an aqueous solution of the complex-forming agent B containing substantially no yttrium is recovered. A method for separating rare earth elements, characterized by recovering. 2. The method for separating rare earth elements according to claim 1, wherein the complexing agent A is ethylenediaminetetraacetic acid, and the complexing agent B is N-hydroxyethylethylenediaminetriacetic acid or diethylenetriaminepentaacetic acid. 3. The strongly acidic cation exchange resin of the adsorption towers A and B and the separation towers A and B is an ion exchange fiber composed of a sulfonic acid group and a carboxylic acid group, and the strongly acidic cation exchange of the adsorption tower C. The method for separating rare earth elements according to claim 1 or 2, wherein the resin is a strongly acidic cation exchange resin having a sulfonic acid group. 4. The strongly acidic cation exchange resin of the separation towers A and B is an ion exchange fiber composed of a sulfonic acid group and a carboxylic acid group, and the strongly acidic cation exchange resin of the adsorption towers A, B and C is The method for separating a rare earth element according to claim 1 or 2, which is a strongly acidic cation exchange resin having a sulfonic acid group. 5. The counter ion of the strongly acidic cation exchange resin of the adsorption tower A and the separation towers A and B is an ammonium ion, and the counter ion of the adsorption towers B and C is a proton. To the method for separating rare earth elements according to any one of 4 to 4. 6. The method for separating rare earth elements according to claim 1, wherein in the step (f), the aqueous acid solution is circulated through the adsorption tower C to concentrate and recover yttrium.