JP5213925B2 - Rare earth metal flocculant - Google Patents

Description

  The present invention relates to a technique for separating rare earth metals, particularly neodymium (Nd) and dysprosium (Dy) mixed in a magnet alloy, etc. by a simple method, specifically, an agent used for separating rare earth metals, and rare earth metals The present invention relates to a metal separation method and a separation apparatus.

  Magnetic alloys used in magnetic recording devices or hybrid vehicles are made of iron as the main component, but a small amount of rare earth metals such as neodymium and dysprosium are added to increase the coercive force. Nowadays, the movement to separate, collect and reuse these is accelerating.

  A conventional method for separating rare earth metals such as Nd and Dy includes a solvent extraction method. First, an alloy containing a plurality of rare earth metals is dissolved in a strong acid, and a phosphoric acid-based extractant and a hydrocarbon-based organic solvent are added. If this is allowed to stand after stirring, the rare earth metal is distributed in a ratio of water and organic solvent depending on the type of extractant (Non-patent Document 1). However, since the difference in distribution rate is not so large depending on the type of rare earth metal, the solvent extraction method is repeated to increase the purity of each metal. Nd and Dy are not so large in the distribution ratio difference, and it is said that solvent extraction is performed several tens of times in order to achieve a purity of 99% or more.

Resource Processing Technology, Volume 37, 157-164 (1990)

  Since the solvent extraction method uses a hydrocarbon-based organic solvent, it is necessary to recover and treat the solvent, which has a large environmental load. Moreover, since the difference in distribution ratio is small, it is necessary to repeat several tens of times. For these reasons, both Nd and Dy are distributed as relatively expensive metals, and the distribution volume is not large. Therefore, it is expected that the procurement of both will become an important issue as hybrid vehicles become more widespread in the future. Therefore, it is required to easily and efficiently recover Nd and Dy from magnets contained in discarded products.

  In addition, phosphors using rare earth metals used in cathode ray tubes, PDPs, and the like are enormous amounts on a global scale, and it is also required to separate and recover rare earth metals from them. However, rare earth metals approximate various physical and chemical properties. For example, the electronegativity of rare earth metals is close to 0.86 to 1.14, and in particular, Nd in magnet alloys is 1.07 and Dy is very close to 1.10. Rare earth metals have an ionic radius of approximately 0.745 to 1.17 mm. Especially, Nd in magnet alloys is close to 0.99 mm and Dy is close to 0.91 mm (both are trivalent ions). is there. The ion radius of rare earth metal ions in this specification is based on Kazuko Matsumoto “Chemistry of rare earth elements”, Asakura Shoten, August 25, 2008, first edition, first edition.

  Accordingly, an object of the present invention is to provide a chemical for separating and recovering a plurality of types of rare earth metals, and a separation and recovery method and apparatus using the chemical.

  As a result of intensive studies by the present inventors in order to solve the above problems, a plurality of rare earth metals can be separated and recovered by using a water-soluble polymer having an amino group and a water-soluble polymer having an acidic group. I found that I can do it.

That is, the present invention includes the following.
(1) a water-soluble polymer having an amino group in a side chain and a main chain being a straight chain;
A rare earth metal flocculant obtained by combining a water-soluble polymer having an acidic group or a cation exchange resin.
(2) The rare earth metal flocculant according to (1), for selectively recovering a rare earth metal ion having the smallest ion radius from a plurality of types of rare earth metal ions.
(3) A water-soluble polymer having an amino group in the side chain and a linear main chain is represented by the general formula (I)
[Where
R ¹ is C ₁ -C ₃ alkylene,
R ² and R ³ independently of one another are hydrogen or C ₁ -C ₃ alkyl]
And / or the general formula (II)
[Wherein R ⁴ is hydrogen or C ₁ -C ₃ alkyl]
The rare earth metal flocculant as described in (1) or (2) which has the structural unit represented by these.
(4) The rare earth metal flocculant according to any one of (1) to (3), wherein the amino group is a tertiary amino group.
(5) a water-soluble polymer having an amino group in a side chain and a main chain being a straight chain;
A water-soluble polymer or cation exchange resin having an acidic group;
A method for recovering a rare earth metal, comprising a step of mixing a plurality of types of rare earth metal ions in an aqueous solution to form an aggregate.
(6) The recovery method according to (5), wherein the rare earth metal ion having the smallest ion radius is selectively recovered from a plurality of types of rare earth metal ions.
(7) The ratio of the number of moles of amino groups to the number of moles of rare earth metal ions having the smallest ionic radius among a plurality of types of rare earth metal ions is 0.1: 1 to 1.3: 1, (5) or (6 ) Collection method.
(8) The recovery method according to any one of (5) to (7), further including a step of dissolving the aggregate by treatment with an acid or a base.
(9) A water-soluble polymer having an amino group in the side chain and a main chain being a straight chain is represented by the general formula (I)
[Where
R ¹ is C ₁ -C ₃ alkylene,
R ² and R ³ independently of one another are hydrogen or C ₁ -C ₃ alkyl]
And / or the general formula (II)
[Wherein R ⁴ is hydrogen or C ₁ -C ₃ alkyl]
The collection | recovery method in any one of (5)-(8) which has a structural unit represented by these.
(10) The recovery method according to any one of (5) to (9), wherein the amino group is a tertiary amino group.
(11) The recovery method according to any one of (5) to (10), wherein the plurality of rare earth metal ions are trivalent neodymium ions and trivalent dysprosium ions.
(12) A mixing tank in which the rare earth metal flocculant according to any one of (1) to (4) and a plurality of types of rare earth metal ions are mixed to form an aggregate; and a filtration unit for filtering the aggregate ;
A rare earth metal recovery device.

  According to the present invention, only a specific rare earth metal can be separated and recovered in a large amount at high speed from an aqueous solution containing a plurality of types of rare earth metals. In particular, only Dy can be separated and recovered in large quantities at high speed from an aqueous solution containing Nd and Dy.

It is a scheme of metal trap / aggregate formation of the present invention. It is a schematic diagram of the metal trap of this invention. 1 is a metal separation scheme of the present invention. It is a schematic diagram of the metal separation / recovery device of the present invention. It is a schematic diagram of the metal separation apparatus of this invention. It is a schematic diagram of the metal collection | recovery apparatus of this invention. It is a schematic diagram of the metal separation / recovery device of the present invention. It is a schematic diagram of the metal separation / recovery device of the present invention. It is a schematic diagram of the metal separation / recovery device of the present invention. It is a schematic diagram of the metal separation apparatus of this invention. It is a schematic diagram of the metal collection | recovery apparatus of this invention.

Hereinafter, the present invention will be described in detail.
1. Basic Principle The basic principle of the present invention will be described using an aqueous solution containing Nd ions having a large ionic radius and Dy ions having a small ionic radius. Nd and Dy are described as typical examples because they are contained in magnet alloys used in various motors, but other examples include, for example, lanthanum (La), cerium (Ce), and europium (Eu) used in phosphors. ), Terbium (Tb), etc., can be carried out based on the same principle.

(1) Method of using a water-soluble polymer having an acidic group
A method for recovering Dy from an aqueous solution in which Nd ions and Dy ions are mixed will be described with reference to FIG. When the magnetic alloy is dissolved with an acid, both Nd and Dy are in the form of trivalent ions. Therefore, in the present invention, both Nd ions and Dy ions mean trivalent ions.

  First, a linear water-soluble polymer 4 having an amino group 3 is added to an aqueous solution in which Nd ions 1 and Dy ions 2 are mixed. Then, Dy ions are preferentially encapsulated in a linear water-soluble polymer having an amino group.

  Next, a solution of the water-soluble polymer 6 having the acidic group 5 is added. Then, an ionic bond 7 composed of an amino group of a linear water-soluble polymer having an amino group and an acidic group of a water-soluble polymer having an acidic group is formed. By the formation of this ionic bond, the water-soluble polymer having an acidic group and the water-soluble polymer having an amino group are cross-linked. Then, this cross-linked product cannot be dissolved in water, and precipitates as an aggregate 8 in which Dy ions are trapped. This agglomerate can be separated by passing through a filtration tank, and as a result, the rare earth metal can be recovered.

  The collected agglomerate dissolves when it is made basic by adding sodium hydroxide or the like, and when it is made basic, a rare earth hydroxide precipitates. By collecting this, it becomes possible to obtain a rare earth hydroxide containing a high proportion of Dy.

  The acidic group of the water-soluble polymer having an acidic group forms a salt structure with the added base. Further, the amino group of the linear water-soluble polymer having an amino group becomes free because the ammonium salt structure with the acidic group of the water-soluble polymer having an acidic group is eliminated. Thus, the aggregate is dissolved by eliminating the ionic bond between the polymers forming the aggregate.

  Aggregates dissolve even when acidified with hydrochloric acid or the like. The amino group of the linear water-soluble polymer having an amino group forms a salt structure with the added acid. Further, the acidic group of the water-soluble polymer having an acidic group is free because the ammonium salt structure with the amino group of the linear water-soluble polymer having an amino group is eliminated. Thus, the aggregate is dissolved by eliminating the ionic bond between the polymers forming the aggregate.

  On the other hand, the rare earth in this case forms a salt structure with the added acid. When an acid that forms a water-soluble rare earth salt, such as hydrochloric acid, is added as the acid to be added, the acid is dissolved together with the polymer used for aggregation. In this case, it is possible to separate the low molecular weight rare earth salt and the high molecular weight water-soluble polymer by using a dialysis membrane or gel filtration. In addition, although the water-soluble polymer which has a carboxyl group as an acidic group is illustrated here, it is the same also in the case of a sulfone group.

  By the way, since the aqueous solution in which Nd ions and Dy ions are mixed is reduced in Dy ions after aggregation, the proportion of Nd ions is relatively increased. Therefore, it is possible to collect Dy with aggregates and Nd with residual liquid.

  The principle of selectively trapping Dy compared to Nd is considered as follows. First, the ion radius of Nd ions is about 0.99 mm, and the ion radius of Dy ions is about 0.91 mm. In other words, Dy ions have a smaller ion radius. When a linear water-soluble polymer having an amino group traps ions, it is presumed that the linear chain forms a ring and traps several ions as shown in FIG.

  However, due to the influence of an amino group or the like, the ring formed by the straight chain is not a circle but is considered to be indefinite. In that case, a large number of ions having a small ion radius can be trapped so as to fill the gap even if the ring is indefinite, but ions having a large ion radius are difficult to trap because they are less likely to enter the gap.

  Among the water-soluble polymers having amino groups, for example, when the main chain is branched like polyethyleneimine, the main chain cannot be a ring for trapping Dy ions, so the Dy ions are coordinated, Alternatively, it is captured by ionic bonds.

  That is, a water-soluble polymer having an amino group with a branched main chain such as polyethyleneimine has a lower ability to selectively trap Dy ions than a water-soluble polymer having an amino group with a main chain being linear. . This is the reason why Dy is selectively trapped compared to Nd.

  From the above, the present technology is not limited to Nd and Dy, but traps rare earth metal ions having a small ion radius by agglomeration from an aqueous solution in which a plurality of types of rare earth metal ions are mixed. By using this technique, in addition to Nd and Dy, for example, the present invention can be applied to the separation and recovery of rare earth from phosphors. Lanthanum (La), cerium (Ce), europium (Eu), and terbium (Tb) used in the phosphors have ionic radii of 1.03, 1.01, 0.95, and 0.92 respectively. By using the technique of the present invention, these elements become Tb, Eu, Ce, and La in the order in which they are easily trapped in the aggregate.

(2) Method of using cation exchange resin In the present invention, a water-soluble polymer having an acidic group is added to form an aggregate with a water-soluble polymer having an amino group. However, a cation exchange resin can be used in place of the water-soluble polymer having an acidic group. Hereinafter, a description will be given with reference to FIG.

  A rare-earth ion with a small ionic radius is added by adding a linear water-soluble polymer 4 having an amino group 3 to an aqueous solution containing two types of rare-earth ions, a rare-earth ion 9 with a small ionic radius and a rare-earth ion 10 with a large ionic radius. Trap. Next, when the cation exchange resin 11 is added, the amino group of the linear water-soluble polymer having an amino group and the acidic group 12 of the cation exchange resin form an ionic bond 13 on the surface of the cation exchange resin. Aggregates trapping rare earth ions with a small ion radius are formed. In this state, rare earth ions having a small ion radius are separated from rare earth ions having a large ion radius by filtration of the cation exchange resin or the like.

  The collected agglomerates on the surface of the cation exchange resin are dissolved by adding sodium hydroxide or the like to be basic, and when the basicity is increased, rare earth hydroxide is precipitated. By collecting this, it becomes possible to obtain a rare earth hydroxide containing a high proportion of rare earth ions having a small ion radius.

  The amino group of the linear water-soluble polymer having an amino group becomes free because the ammonium salt structure with the acidic group of the cation exchange resin is eliminated. Thus, the aggregate is dissolved by eliminating the ionic bond between the polymers forming the aggregate. The linear water-soluble polymer having an amino group can be recovered and used again for rare earth separation and recovery.

  Aggregates dissolve even when acidified with hydrochloric acid or the like. The amino group of the linear water-soluble polymer having an amino group forms a salt structure with the added acid. Thus, the aggregate is dissolved by eliminating the ionic bond between the polymers forming the aggregate.

  On the other hand, the rare earth in this case forms a salt structure with the added acid. When an acid that forms a water-soluble rare earth salt, such as hydrochloric acid, is added as the acid to be added, the acid is dissolved together with the polymer used for aggregation. In this case, it is possible to separate the low molecular weight rare earth salt and the high molecular weight water-soluble polymer by using a dialysis membrane or gel filtration.

2. The present invention relates to a water-soluble polymer having an amino group in a side chain and a main chain being linear (hereinafter also referred to as “amino group-containing water-soluble polymer”), and a water-soluble polymer having an acidic group. The present invention relates to a rare earth metal flocculant formed by combining a functional polymer (hereinafter also referred to as “acidic group-containing water-soluble polymer”) or a cation exchange resin. Here, “combined” means a rare earth metal flocculant containing an amino group-containing water-soluble polymer and an acidic group-containing water-soluble polymer or cation exchange resin in a separated state, and an amino group-containing water-soluble polymer. It means that any of the rare earth metal flocculants containing the molecule and the acidic group-containing water-soluble polymer or cation exchange resin in a mixed state is included.

  By using the rare earth metal flocculant according to the present invention, a rare earth metal having the smallest ionic radius among specific rare earth metal ions, that is, rare earth metal ions present in the aqueous solution, from an aqueous solution containing a plurality of types of rare earth metal ions. Ions can be selectively separated and recovered.

(1) Amino group-containing water-soluble polymer The amino group-containing water-soluble polymer used in the present invention is a water-soluble polymer having an amino group in a side chain and a main chain being linear as described above. . The main chain is not particularly limited as long as it can trap rare earth metal ions, but it is preferably a main chain composed of hydrocarbons or a main chain composed of hydrocarbons and SO ₂ . The side chain is not particularly limited as long as it has an amino group, but -R ¹ -NR ² R ³ (wherein R ¹ is C ₁ -C ₃ alkylene, preferably methylene, R ² and R ³ Are independently of each other hydrogen or C ₁ -C ₃ alkyl, preferably both methyl) or 5-7 membered nitrogen-containing alicyclic heterocycles formed with the main chain carbon atoms (eg , Pyrrolidine formed together with two adjacent carbon atoms of the main chain).

The amino group-containing water-soluble polymer used in the present invention is represented by the general formula (I)
[Where
R ¹ is C ₁ -C ₃ alkylene, preferably methylene or ethylene, more preferably methylene;
R ² and R ³ independently of one another are hydrogen or C ₁ -C ₃ alkyl, preferably both hydrogen, more preferably one is hydrogen and the other is methyl, particularly preferably both are methyl. ]
And / or the general formula (II)
[Wherein R ⁴ is hydrogen or C ₁ -C ₃ alkyl, preferably hydrogen or methyl, more preferably methyl]
It is preferable to have the structural unit represented by these.

Furthermore, the amino group-containing water-soluble polymer used in the present invention has the following chemical formula:
[Wherein, m is a positive integer, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the number average of the amino group-containing water-soluble polymer. An integer such that the molecular weight is between 500 and 200,000];
[Wherein, m and n are positive integers, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the amino group-containing water-soluble polymer. An integer such that the number average molecular weight is between 500 and 200,000];
[Wherein, n is a positive integer, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the number average of the amino group-containing water-soluble polymer. An integer such that the molecular weight is between 500 and 200,000];
[Wherein, n is a positive integer, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the number average of the amino group-containing water-soluble polymer. An integer such that the molecular weight is between 500 and 200,000];
[Wherein, m and n are positive integers, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the amino group-containing water-soluble polymer. An integer such that the number average molecular weight is between 500 and 200,000];
[Wherein, m and n are positive integers, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the amino group-containing water-soluble polymer. An integer such that the number average molecular weight is between 500 and 200,000];
[Wherein, n is a positive integer, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the number average of the amino group-containing water-soluble polymer. An integer such that the molecular weight is between 500 and 200,000]; or
[Wherein, n is a positive integer, preferably an integer such that the number average molecular weight of the amino group-containing water-soluble polymer is 200 to 1,000,000, more preferably the number average of the amino group-containing water-soluble polymer. An integer such that the molecular weight is between 500 and 200,000];
It is preferable that it is the compounds 1-8 represented by these.

  The amino group can selectively trap rare earth metal ions having the smallest ion radius, regardless of whether the amino group is primary, secondary, or tertiary, but it is more selective by using a tertiary amino group. Separation and recovery of rare earth metals can be performed. This is supported by actual experimental results and computational chemistry shown below.

  Compound 1, Compound 1 in which one hydrogen of the amino group of Compound 1 is changed to a methyl group (Compound 1 ′), Compound in which two hydrogens of the amino group of Compound 1 are changed to a methyl group (Compound 1 ″) Was synthesized. The amino group of Compound 1 is a primary amino group, the amino group of Compound 1 ′ is a secondary amino group, and the amino group of Compound 1 ″ is a tertiary amino group. Aggregation experiments were performed using these. Then, when the ratio of selectively aggregating Dy was arranged in descending order, the order was compound 1 ″, compound 1 ′, and compound 1. In other words, the ratio of selectively trapping Dy is the highest when the amino group is tertiary, and is in the order of secondary and primary below.

  When molecular orbital calculation was performed by the density functional method, the binding energies for Nd of Compound 1, Compound 1 ′, and Compound 1 ″ were 6.9 kcal / mol, 7.5 kcal / mol, and 8.4 kcal / mol, respectively. On the other hand, the binding energies for Dy were 10.2 kcal / mol, 11.5 kcal / mol, and 12.9 kcal / mol, respectively.

  The values obtained by subtracting the bond energy with Nd from the bond energy with Dy were 3.3 kcal / mol, 4.0 kcal / mol, and 4.5 kcal / mol for Compound 1, Compound 1 ′, and Compound 1 ″, respectively. This result shows that compound 1 '', which has the largest difference in bond energy between Dy and Nd, that is, a compound having a tertiary amino group is most likely to selectively trap Dy, followed by secondary amino group It is shown that the selectivity decreases in the order of the compound having, and the compound having a primary amino group.

  This is in good agreement with the selectivity order in actual experiments. For this reason, the difference in the selectivity of Dy traps due to the difference in the amino group series is considered to be due to the difference in binding energy between Dy and Nd.

  As described above, it is preferable to use a polymer having a tertiary amino group for selective separation and recovery of rare earth metals, but a water-soluble polymer having a combination of primary to tertiary amino groups is used. Even high selectivity can be achieved. Moreover, more selective separation and recovery can be performed by using a water-soluble polymer having a cyclic amino group.

  The amino group-containing water-soluble polymer generates an amine-specific odor even at room temperature when the number average molecular weight is small. Specifically, it becomes prominent when the number average molecular weight is less than 200. Therefore, the number average molecular weight of the amino group-containing water-soluble polymer is preferably 200 or more. In order to make the odor hardly felt, the number average molecular weight is preferably 500 or more if possible.

  On the other hand, when the number average molecular weight is increased, the viscosity of the aqueous solution is high, and handling becomes difficult at the time of the input amount control and the input operation to the metal-containing water. Specifically, when the number average molecular weight exceeds 1,000,000, the viscosity becomes 3,000 mPa · s or more even with a 10% by weight aqueous solution. Therefore, the number average molecular weight of the amino group-containing water-soluble polymer is preferably 1,000,000 or less. In addition, even with a 10% by weight aqueous solution, the viscosity is 1,000 mPa · s or less, and the number of amino group-containing water-soluble polymers can be easily controlled in order to manage the input amount or to perform the input operation into metal-containing water. The average molecular weight is preferably 200,000 or less. The number average molecular weight is measured by gel permeation chromatography (GPC).

(2) Acid group-containing water-soluble polymer The acid group-containing water-soluble polymer used in the present invention is a water-soluble polymer having an acid group as described above. Since the selective trap of rare earth metal ions mainly depends on the amino group-containing water-soluble polymer, the acidic group-containing water-soluble polymer used in the present invention reacts with the amino group-containing water-soluble polymer. There is no particular limitation as long as it can form an aggregate. Moreover, an acidic group will not be specifically limited if it can react with an amino group, For example, a carboxyl group, a sulfonic acid group, a phosphoric acid group etc. can be mentioned.

  As the water-soluble polymer having a carboxyl group, for example, polyacrylic acid is preferable because it is inexpensive and easily ion-bonds with an amino group. In addition, polymethacrylic acid, a copolymer of polyacrylic acid and polymethacrylic acid, and the like are also included. These are polymers in which an acidic group is bonded to a main chain composed of straight chain hydrocarbons.

  Examples of the water-soluble polymer having a sulfonic acid group include polyvinyl sulfonic acid and polystyrene sulfonic acid. Since the sulfonic acid group has a higher acidity than the carboxyl group, it has a high ratio of forming an ionic bond with an amino group and is preferable in that a stable aggregate can be obtained.

  In the present invention, it is also preferable to use a copolymer of an acidic group-containing water-soluble polymer and a polymer having no acidic group. Examples of the polymer having no acidic group include polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polybutyl acrylate, polyhexyl acrylate, polyoctyl acrylate, polydecyl acrylate, and polyacrylic acid. Examples include dodecyl, polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, polyhexyl methacrylate, polyoctyl methacrylate, polydecyl methacrylate, polydodecyl methacrylate, and polystyrene. The copolymer is obtained by mixing and polymerizing a monomer of an acid group-containing water-soluble polymer and a polymer monomer having no acid group, but the mixing ratio is 50% for the monomer of the acid group-containing water-soluble polymer. It is preferable that it is more than mol% (for example, 50 to 90 mol%). This is because when it is less than 50 mol%, it is difficult to dissolve in water.

  If the number average molecular weight of the acidic group-containing water-soluble polymer is too low, the number of cross-linked sites of the aggregate decreases, and the stability of the aggregate decreases. In addition, the agglomerates tend to become liquids with high viscosity. In this case, it becomes difficult to collect the aggregate by filtration. Therefore, the number average molecular weight of the acidic group-containing water-soluble polymer is preferably 2,000 or more.

  When the temperature of the aqueous solution containing the rare earth metal is 40 ° C. or higher, the aggregate has adhesiveness when the number average molecular weight is 2,000. In the case immediately after the rare earth is dissolved in the acid, the temperature may increase to about 60 ° C. In this case, the aggregate can be solidified even at a high temperature by further increasing the number average molecular weight. Specifically, by setting the number average molecular weight to 5,000 or more, the aggregate can be solidified even when the temperature of the rare earth-containing aqueous solution is 40 ° C. Therefore, the number average molecular weight of the acidic group-containing water-soluble polymer is more preferably 5,000 or more. Furthermore, by setting the number average molecular weight to 10,000 or more, it becomes possible to solidify the agglomerates even when the temperature of the waste water is 60 ° C. Therefore, the number average molecular weight of the acidic group-containing water-soluble polymer is more preferably 10,000 or more.

  On the other hand, if the number average molecular weight is too large, the acidic group-containing water-soluble polymer is difficult to dissolve in water. Then, a dilute solution of the acidic group-containing water-soluble polymer is prepared using a large amount of water and used for aggregation. This is not practical because the amount of drainage becomes enormous. Therefore, the number average molecular weight of the acidic group-containing water-soluble polymer is preferably 200,000 or less, and more preferably 100,000 or less. Thereby, the amount of drainage can be reduced to a practical level.

(3) Cation exchange resin In this invention, a cation exchange resin can also be used instead of an acidic group containing water-soluble polymer. Cation exchange resins are resin particles having a large number of acidic groups such as carboxyl groups and sulfonic acid groups on the surface, and are often porous in order to increase the surface area and increase ion exchange efficiency. After the cation exchange resin is ionically bonded to the amino group-containing water-soluble polymer in which rare earth ions are trapped, it can be separated by filtration from an aqueous solution in which a plurality of types of rare earth ions are mixed. Thereafter, the ionic bond with the amino group-containing water-soluble polymer in which rare earth ions are trapped can be released with an aqueous solution of a base or an acid. Moreover, it is possible to regenerate the cation exchange resin by a normal method for regenerating the ion exchange resin (method of washing with an acid followed by distilled water).

  It is not necessary to use a special cation exchange resin used in the present invention, and a general-purpose grade can be used.

  In addition, when magnetic resin is contained inside the resin, or when metal powder having ferromagnetism is contained, the cation exchange resin is separated from an aqueous solution in which a plurality of rare earth ions are mixed by magnetic separation without filtration. can do.

3. Method for recovering rare earth metal The method for recovering a rare earth metal according to the present invention comprises a water-soluble polymer having an amino group in a side chain and a main chain being linear, and a water-soluble polymer having an acid group or cation exchange. And a step of mixing a resin and a plurality of types of rare earth metal ions in an aqueous solution to form an aggregate. More specifically, a step of adding an amino group-containing water-soluble polymer and an acid group-containing water-soluble polymer or a cation exchange resin to an aqueous solution containing a plurality of rare earth metal ions to form an aggregate. Including.

  The recovery method according to the present invention selectively traps a rare earth metal ion having the smallest ion radius in an aqueous solution containing a plurality of types of rare earth metal ions with an amino group-containing water-soluble polymer, and then the rare earth metal. It is based on the principle that an amino group-containing water-soluble polymer in which ions are trapped is reacted with an acidic group-containing water-soluble polymer or a cation exchange resin to form an aggregate.

  The rate at which the amino group-containing water-soluble polymer traps rare earth metal ions is faster than the rate at which the acid group-containing water-soluble polymer or cation exchange resin forms aggregates. Therefore, the order of adding the amino group-containing water-soluble polymer and the acidic group-containing water-soluble polymer or cation exchange resin is not important, and any water-soluble polymer may be added first. Moreover, you may add each water-soluble polymer simultaneously.

  The amino group-containing water-soluble polymer selectively traps the rare earth metal ions having the smallest ionic radius, and when all of the smallest rare earth metal ions are separated and recovered, the next smallest rare earth metal ions are selectively trapped. Therefore, by appropriately adjusting the amount of the amino group-containing water-soluble polymer to be added and performing the recovery method according to the present invention a plurality of times, different rare earth metal ions can be selectively recovered each time.

  On the other hand, when the number of amino groups and acidic groups in the water-soluble polymer is larger than the number of rare earth metal ions having the smallest ionic radius, coordination bonds, ionic bonds, etc. are formed between the functional groups and the rare earth metal ions. Is done. Since these bonds do not significantly affect the ion size, not only rare earth ions having a small ion radius but also rare earth ions having a large ion radius are trapped in the aggregate in a similar manner. Therefore, it is desirable that the amino group-containing water-soluble polymer is added in such an amount that the number of moles of amino groups is the same or less than the number of moles of rare earth ions having the smallest ionic radius. Specifically, when the number of moles (M) of the rare earth metal ion having the smallest ionic radius is 1, the number of moles of amino groups (PB) of the amino group-containing water-soluble polymer is preferably 1.3 or less. . More specifically, PB: M is preferably 0.1: 1 to 1.3: 1, more preferably 0.5: 1 to 1.2: 1, and particularly preferably 0.8: 1 to 1: 1. . Here, the “number of moles of amino group” is not the number of amino groups contained in one molecule of an amino group-containing water-soluble polymer, but by adding the amino group-containing water-soluble polymer to the aqueous solution. It means the number of all amino groups that will be present.

  The role of the acidic group-containing water-soluble polymer is to form an ionic bond with the amino group of the amino group-containing water-soluble polymer to form an insoluble aggregate in water. If the number of acidic groups in the acidic group-containing water-soluble polymer is larger than the number of rare earth ions with the smallest ionic radius, the acidic groups will ionically bond with rare earth ions with the smallest ionic radius and rare earth ions with a larger ionic radius. Thus, this bonded substance is further ionically bonded to the amino group of the amino group-containing water-soluble polymer to form an insoluble aggregate in water. Therefore, selective aggregation with respect to rare earth ions having a small ion radius is difficult to occur.

  Therefore, the amount of acidic group-containing water-soluble polymer added is less than the number of moles (M) of the rare earth metal ions having the smallest ionic radius in terms of the number of acidic groups (PA) in the acidic group-containing water-soluble polymer. The amount is preferably the same as or less than the number of moles of amino groups (PB) in the amino group-containing water-soluble polymer (that is, PA ≦ PB). The role and addition amount of the cation exchange resin are the same as in the case of the acidic group-containing water-soluble polymer.

  In the rare earth metal recovery method according to the present invention, all rare earth metals, that is, scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium ( Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), Lutetium (Lu) can be separated.

  In particular, in the rare earth metal recovery method according to the present invention, it is preferable to separate a plurality of types of rare earth metal ions having an ion radius difference of 0.01 Å or more, and a plurality of types of rare earth metal ions having an ion radius difference of 0.04 Å or more. Is more preferable, and it is particularly preferable to separate a plurality of types of rare earth metal ions having an ion radius difference of 0.06 mm or more.

  More specifically, selectively recovering Dy from an aqueous solution containing Nd and Dy, selectively recovering Y from an aqueous solution containing Ce and Y, and an aqueous solution containing La and Tb It is preferable to selectively recover Tb from the aqueous solution, and to selectively recover Tb from an aqueous solution containing La, Ce, and Tb. Further, it is particularly preferable to selectively recover Dy from an aqueous solution containing trivalent Nd ions and trivalent Dy ions.

  The method for recovering a rare earth metal according to the present invention further includes a step of dissolving an aggregate comprising an amino group-containing water-soluble polymer and an acid group-containing water-soluble polymer or a cation exchange resin by treatment with an acid or a base. You may go out. The acid used for dissolving the aggregate is not particularly limited, but an inorganic acid is preferably used, and specifically, hydrochloric acid, sulfuric acid, nitric acid and the like are preferably used. Further, the base used for dissolving the aggregate is not particularly limited, but it is preferable to use an inorganic base. Specifically, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferable. Is preferably used.

4). Rare earth metal recovery device (1) Invention 1 of metal separation / recovery device
A rare earth metal recovery device according to the present invention includes a mixing tank in which the above rare earth metal flocculant and a plurality of types of rare earth metal ions are mixed to form an aggregate, and a filtration unit that filters the aggregate. The said apparatus is demonstrated concretely using FIG.

  First, an aqueous solution containing a plurality of types of rare earth ions is introduced into the mixing tank through the pipe 16 by the pump 15 in the mixing tank 14. Next, an aqueous solution of an amino group-containing water-soluble polymer is introduced into the mixing tank 14 from the first tank 17 by the pump 18 through the pipe 19. The amino group-containing water-soluble polymer introduced selectively traps rare earth ions having the smallest ionic radius in an aqueous solution containing a plurality of types of rare earth ions.

  Next, an aqueous solution of the acidic group-containing water-soluble polymer is introduced into the mixing tank 14 from the second tank 20 by the pump 21 through the pipe 22. After the introduction of the aqueous solution containing plural kinds of rare earth ions, the aqueous solution is continuously stirred by the overhead stirrer 24 equipped with the stirring blade 23. As a result, an aggregate 25 composed of the amino group-containing water-soluble polymer and the acidic group-containing water-soluble polymer is formed in the mixing tank. Stirring is stopped after aggregate formation.

  Subsequently, when the shutter 26 is opened, liquid other than the aggregate is discharged from the mixing tank through the filter 27. Aggregates are dammed by the filter and are not discharged from the mixing tank. After the liquid component in the mixing tank is discharged, the shutter is closed.

  Next, when a hydrochloric acid aqueous solution is introduced into the mixing tank from the third tank 28 by the pump 29 through the pipe 30, the aggregates are dissolved. When the shutter is opened again, the liquid in which the aggregates are dissolved is discharged from the mixing tank through the filter and enters the metal recovery tank 31. Note that the valve 32 controls whether or not to put into the metal recovery tank.

  Subsequently, a sodium hydroxide aqueous solution is introduced into the metal recovery tank from the fourth tank 33 through the pipe 35 by the pump 34. Then, rare earth metal ions are precipitated as rare earth metal hydroxide 36 which is hardly soluble in water. When the shutter 37 at the bottom of the metal recovery tank is opened, the liquid enters the drug recovery tank 39 from the recovery tank via the filter 38.

  By extracting the rare earth metal hydroxide remaining in the metal recovery tank, the recovery of the rare earth with a small ion radius is completed.

  Although not shown here, after these operations are finished, the mixing tank and the recovery tank can be washed with purified water or the like to remove hydrochloric acid adhering to the wall surface or the like. Further, the charging order of the acidic group-containing water-soluble polymer and the amino group-containing water-soluble polymer may be reversed.

(2) Form 2 of the invention of the metal separation / recovery device
Of the rare earth metal separation / recovery device of the present invention, a configuration for separating and collecting rare earth metal using a magnetic separation method will be described with reference to FIGS.

  First, the magnetic powder is mixed with the amino group-containing water-soluble polymer aqueous solution in the second tank. When the magnetic powder is introduced into the mixing tank together with the amino group-containing water-soluble polymer aqueous solution from the second tank, an aggregate is formed, and the magnetic powder is contained in the aggregate.

  This apparatus has a magnetic powder-containing aggregate transport mechanism including a first roller 40, a second roller 41, a third roller 42, a fourth roller 43, and a belt 44. The belt surface between the fourth roller and the first roller through the second roller has a magnetic structure so that the agglomerates containing magnetic powder in the first mixing tank adhere to the belt surface. Can do. Since there is no magnetic force from the second roller to the fourth roller, the aggregate comes off the third roller and falls into the aggregate recovery tank 45. In this way, the aggregate which trapped the metal ion is collected in the aggregate recovery tank.

Next, the process of recovering the metal from the aggregate in which the metal ions are trapped will be described with reference to FIG.
First, an aqueous hydrochloric acid solution is charged into the agglomerate collection tank through a pipe from a third tank by a pump. Then, the aggregate is dissolved. When the shutter 46 is opened, the liquid in which the aggregates are dissolved and the magnetic powder are introduced into the metal recovery tank through the filter 47. Subsequently, when a sodium hydroxide aqueous solution is introduced into the metal recovery tank from the fourth tank 33 through the pipe 35 by the pump 34, the dissolved rare earth metal is converted into a hydroxide and deposited. When the shutter 37 is opened, the dissolved acidic group-containing water-soluble polymer and amino group-containing water-soluble polymer enter the drug recovery tank 39 through the filter 38. The deposited rare earth metal hydroxide remains on the filter 38. In this way, the rare earth metal can be selectively recovered by using the magnetic separation method.

(3) Invention Mode 3 for Metal Separation / Recovery Device
The basic configuration of the metal separation / recovery device of the present invention when a cation exchange resin is used instead of the acidic group-containing water-soluble polymer will be described with reference to FIG.

  After the aqueous solution of the amino group-containing water-soluble polymer is added to the aqueous solution containing a plurality of types of rare earth ions, the cation exchange resin 50 is added from the container 48 through the passage 49. The amount added is controlled by a valve 51. In this way, the amino group-containing water-soluble polymer that traps rare-earth ions having a small ionic radius is ionically bonded to the surface of the cation exchange resin.

  When the aqueous solution containing a plurality of types of rare earth ions is discharged from the mixing tank and then an aqueous solution of hydrochloric acid is added, the amino group-containing water-soluble polymer is removed from the cation exchange resin. Thereafter, the cation exchange resin is regenerated by washing with purified water, and can form ion bonds with the amino group-containing water-soluble polymer again.

  On the other hand, the amino group-containing water-soluble polymer separated from the cation exchange resin is stored in a metal recovery tank. Here, when a sodium hydroxide aqueous solution is added, the rare earth ions having a small ionic radius become hydroxide and precipitate. Further, by opening the shutter of the metal recovery tank, the aqueous solution of the amino group-containing water-soluble polymer is transferred to the drug recovery tank. The operation is completed by recovering the rare earth metal hydroxide with a small ionic radius remaining in the metal recovery tank.

(4) Form 4 of metal separator / collector
Of the metal separation / recovery device of the present invention, a configuration in which a cation exchange resin is packed in a column will be described with reference to FIG.

  After mixing an aqueous solution of an amino group-containing water-soluble polymer with an aqueous solution containing a plurality of types of rare earth ions, this mixture is filled with a cation exchange resin through a pipe 53 by a pump 52, and the lower part is a mesh 54. Into column 55. A pressurizing mechanism 56 using compressed air or compressed nitrogen is provided at the top of the column. Thus, the operation of removing the ion exchange resin from the mixing tank becomes unnecessary by filling the column with the cation exchange resin.

(5) Form 5 of metal separation / recovery device
Of the metal separation / recovery device of the present invention, a configuration in which a cation exchange resin is filled in a column and an electrode is provided in the column will be described with reference to FIG.

  First, not the sodium hydroxide aqueous solution but the sodium chloride aqueous solution is put in the fourth tank. In the above embodiment, immediately after the sodium hydroxide aqueous solution is charged (in this embodiment, immediately after the sodium chloride aqueous solution is charged), a potential difference is generated between the electrodes 57 by the power source 58, so that the sodium chloride is electrolyzed, Sodium oxide is produced.

  Members containing 5% or more of sodium hydroxide (including solutions) are designated as deleterious substances and must be handled with care. However, by using the apparatus and method of the present embodiment, it becomes possible to perform separation and recovery of rare earth metals without directly using deleterious sodium hydroxide. By controlling the power supply, it is possible to generate a minimum amount of sodium hydroxide, so that there is an advantage that the burden is reduced even in the drainage treatment.

  In this embodiment mode, an alkali metal such as potassium chloride or lithium chloride can be used instead of sodium chloride. The potential difference between the electrodes is set to a value greater than that necessary for the alkali metal chloride to be used to become a hydroxide.

(6) Form 6 of metal separator / collector
Of the metal separation / recovery device of the present invention, a configuration using cation exchange resin and magnetic separation will be described with reference to FIGS.

  In this embodiment, a cation exchange resin containing magnetic powder inside is used. The cation exchange resin is combined with the amino group-containing water-soluble polymer trapped with rare earth ions, and then recovered in the aggregate recovery tank 45 by the magnetic powder-containing aggregate transport mechanism consisting of the first roller, the fourth roller, and the belt 44. Is done.

  Thereafter, the rare earth metal can be recovered by the same process as in the second embodiment using the apparatus shown in FIG.

  When this form is used, the amino group of the amino group-containing water-soluble polymer that was a hydrochloride structure is regenerated by sodium hydroxide added when the rare earth metal is converted into a hydroxide, and this polymer itself is also regenerated. The Furthermore, cation exchange resins can be regenerated by adding hydrochloric acid. Therefore, by performing this embodiment, it is possible to regenerate both the amino group-containing water-soluble polymer and the cation exchange resin. By regenerating both, it is possible to reduce waste and reduce member costs when separating and collecting rare earth metals.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited to this.

[Example 1]
An aqueous solution in which neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyCl ₃ ) are dissolved in water is prepared. At this time, the Nd and Dy concentrations are both adjusted to 500 ppm.

  Add 35 g of this aqueous solution (total number of two kinds of rare earth metal ions is 0.916 mmol) in a container and add 0.067 g (0.093 mmol) of 10 wt% polyacrylic acid with a number average molecular weight of 5,000 while stirring. . Further, an appropriate amount of a 10% by weight aqueous solution of the above compounds 1 to 8 is added (the number of repeating units is 0.458 mmol, or 0.229 mmol when there are two amino groups in the repeating unit). Then, white aggregates are generated. If left for several hours, it settles to the bottom of the container. Aspirate the solution with a pipette, etc., so that the container is almost agglomerated.

  Next, an operation for washing the aggregate is performed. Specifically, 35 g of purified water is added, and after stirring with an ultrasonic cleaner, the solution portion is sucked out with a pipette or the like so that only the agglomerates are contained in the container. After performing this washing operation 5 times, 0.5 mol / liter hydrochloric acid is added dropwise until the aggregates are completely dissolved. Add water until the liquid weight in the container is 35g.

  The concentration of Nd and Dy in this solution was investigated using inductively coupled plasma (ICP) analysis. The value examined here is the concentration of Nd and Dy trapped in the aggregate. The results are shown in Table 1.

  When using compounds 1 to 8, it was found that Dy had a higher trap rate to aggregates. All of these compounds have a linear main chain structure. On the other hand, when polyethyleneimine with a branched main chain was used, there was no difference in the trap rate of Nd and Dy.

  From the above, it was clarified that the water-soluble polymer having an amino group selectively traps Dy having a smaller ionic radius than Nd when the main chain is not branched but is linear.

  When compared with the amino group series, when a polymer having a tertiary amine (compounds 2, 4, 6, and 8) is used, the Nd trap rate tends to be low and the Dy trap rate tends to be high. Next, the polymer with the secondary amine having the highest Dy trap rate (compounds 3, 5, and 7), and the compound 1 having only the primary amine had the lowest Dy trap rate. It was also found that the polymers having a plurality of series amino groups (compounds 2, 5, and 6) are all close to the trap rate of amino groups having a large series.

  From the above, it became clear that water-soluble polymers with amino groups and linear main chains trap Dy with a smaller ionic radius more selectively with Nd as the series of amino groups is larger. .

  Comparing the structures of the amino groups, the compounds 3 to 8 have a cyclic amine structure. Compound 2 and compound 6 have two amino groups, one of which is an acyclic primary amine. The other is compound 2 is an acyclic tertiary amine and compound 6 is a cyclic tertiary amine. Comparing compounds 2 and 6, compound 6 has a lower Nd trap rate. Compound 2 has a slightly lower Dy trap rate.

  Based on the above, for water-soluble polymers with amino groups and straight-chain main chains, Dy, which has a smaller ionic radius than Nd, is better for cyclic amino groups than for acyclic amino groups. It became clear to trap.

[Example 2]
The same experiment as in Example 1 was performed except that 0.067 g of a 28.6 wt% aqueous solution of polystyrenesulfonic acid having a number average molecular weight of 200,000 (0.093 mmol) was used instead of polyacrylic acid. As a result, the difference between the trap rates of Nd and Dy in the aggregate with respect to the results when polyacrylic acid was used was ± 10% or less. Therefore, it was revealed that Dy having a small ionic radius can be selectively trapped in the aggregate even when polystyrene sulfonic acid is used.

[Example 3]
An experiment similar to that of Example 1 was performed except that a cation exchange resin (a type having a sulfonic acid group on the surface, and an amount such that the number of sulfonic acid groups on the surface was 0.093 mmol) was used instead of polyacrylic acid. . As a result, the difference between the trap rates of Nd and Dy in the aggregate with respect to the results when polyacrylic acid was used was ± 10% or less. Therefore, it was clarified that Dy having a smaller ionic radius than Nd can be selectively trapped in the aggregate even when a cation exchange resin is used.

[Example 4]
The NdCl ₃ and DyCl ₃ in place of the aqueous solution 35g were mixed at 500ppm as chlorides of the rare earth metals, also yttrium chloride (YCl ₃₎ a chloride of a rare earth metal, an aqueous solution of cerium chloride (CeCl ₃₎ were mixed in 500ppm 26.1 An experiment similar to that in Example 1 was attempted except that g (the total number of the two kinds of rare earth metal ions was 0.916 mmol) was used.

  Since the ion radii of Y and Ce are 0.9 mm and 1.01 mm, respectively, Y has a smaller ion radius. The results are shown in Table 2.

  Compared with Ce, Y, which has a smaller ion radius, had a higher trapping rate on aggregates. In addition, in the case of a water-soluble polymer having an amino group, when the main chain is a straight chain rather than a branched chain, the larger the amino group series, the smaller the ionic radius Y in comparison with Ce when the main chain is a cyclic amine. Trap more selectively.

[Example 5]
The NdCl ₃ and DyCl ₃ in place of the aqueous solution 35g were mixed at 500ppm as chlorides of the rare earth metals, also of lanthanum chloride (LaCl ₃₎ a chloride of the rare earth metals, aqueous terbium chloride (TbCl ₃₎ were mixed in 500ppm 34g An experiment similar to that of Example 1 was tried except that the total number of the two kinds of rare earth metal ions was 0.916 mmol.

  Since the ionic radii of Tb and La are 0.92Å and 1.03Å, respectively, Tb has a smaller ionic radius. The results are shown in Table 3.

  Compared with La, Tb with a smaller ionic radius had a higher trapping rate on aggregates. In addition, a water-soluble polymer having an amino group has a Tb having a smaller ionic radius than La when the main chain is linear rather than branched, and the larger the amino group, the more the cyclic group is a cyclic amine. Trap more selectively.

[Example 6]
Rare earth metal chlorides lanthanum chloride (LaCl ₃ ), cerium chloride (CeCl ₃ ), terbium chloride (TbCl ₃ ) instead of 35 g of an aqueous solution containing 500 ppm each of NdCl ₃ and DyCl ₃ as rare earth metal chlorides The same experiment as in Example 1 was attempted except that 19.6 g of an aqueous solution in which 500 ppm of each of the above three types was mixed (the total number of the three rare earth metal ions was 0.916 mmol) was used.

  Since the ion radii of Tb, Ce, and La are 0.92Å, 1.01Å, and 1.03 そ れ ぞ れ, respectively, the ion radius of Tb is the smallest among these three types. The results are shown in Table 4.

  Compared to La and Ce, Tb with a smaller ionic radius showed a higher trapping rate for aggregates. In addition, a water-soluble polymer having an amino group has a smaller ionic radius than La and Ce when the main chain is a straight chain rather than a branched chain, and when the amino group has a larger series, it is a cyclic amine. Tb was trapped more selectively.

  From Examples 1 to 3 and Examples 4 to 6, by using the technique of the present invention, a rare earth metal having a small ionic radius is selectively aggregated even in an aqueous solution in which rare earth metals other than Nd and Dy are mixed. It became clear that it could be trapped in things.

[Example 7]
When the mixed solution of rare earth metal, the aqueous solution of polyacrylic acid, and the aqueous solution of the water-soluble polymer having an amino group were used in the same proportion as in Example 1, separation and recovery of the rare earth metal was performed with the apparatus of FIG. 4 as the apparatus. The trap rate of Nd and Dy on the aggregates was ± 5% or less of the results shown in Table 1.

  Therefore, it has been clarified that the rare earth having a small ion radius can be selectively recovered even when the apparatus of the present invention is used.

1 ... Nd ion
2… Dy ion
3… Amino group
4… Amino group-containing water-soluble polymer
5… Acid group
6… Water-soluble polymer containing acidic groups
7… Ion bond
8 ... Dy ions trapped aggregate
9 ... Rare earth ions with small ion radius
10… Rare earth ions with large ion radius
11… Cation exchange resin
12… Acid group of cation exchange resin
13… Ion bond
14 ... Mixing tank
15 ... Pump
16 ... Piping
17 ... 1st tank
18 ... Pump
19 ... Piping
20 ... second tank
21 ... Pump
22 ... Piping
23 ... stirring blade
24… Overhead stirrer
25. Aggregates composed of water-soluble polymer containing amino group and water-soluble polymer containing acid group
26 ... Shutter
27 ... Filter
28 ... Third tank
29 ... Pump
30 ... Piping
31 ... Metal recovery tank
32… Valve
33 ... Fourth tank
34 ... Pump
35 ... Piping
36 ... Rare earth metal hydroxide
37 ... Shutter
38 ... Filter
39… Drug collection tank
40 ... first roller
41 ... second roller
42 ... Third roller
43 ... Fourth roller
44… Belt
45 ... Aggregate collection tank
46 ... Shutter
47 ... Filter
48 ... container
49 ... Aisle
50… Cation exchange resin
51… Valve
52 ... Pump
53 ... Piping
54 ... Mesh
55 ... Column
56 ... Pressure mechanism
57… Electrodes
58… Power supply

Claims (9)

A water-soluble polymer having an amino group in a side chain and a linear main chain;
A rare earth metal flocculant for selectively recovering a rare earth metal ion having the smallest ion radius from a plurality of types of rare earth metal ions, which is formed by combining a water-soluble polymer having an acidic group or a cation exchange resin. A water-soluble polymer having an amino group in the side chain and a linear main chain is represented by the general formula (I)
[Where
R ¹ is C ₁ -C ₃ alkylene,
R ² and R ³ independently of one another are hydrogen or C ₁ -C ₃ alkyl]
And / or the general formula (II)
[Wherein R ⁴ is hydrogen or C ₁ -C ₃ alkyl]
A structural unit represented in the rare earth metal coagulant of claim 1. The rare earth metal flocculant according to claim 1 or 2 , wherein the amino group is a tertiary amino group. A water-soluble polymer having an amino group in a side chain and a linear main chain;
A water-soluble polymer or cation exchange resin having an acidic group;
Rare earth metal for selectively recovering rare earth metal ions having the smallest ion radius from a plurality of types of rare earth metal ions, including a step of mixing a plurality of types of rare earth metal ions in an aqueous solution to form an aggregate. Recovery method. The recovery method according to claim 4 , wherein the ratio of the number of moles of amino groups to the number of moles of rare earth metal ions having the smallest ionic radius among a plurality of types of rare earth metal ions is 0.1: 1 to 1.3: 1. The recovery method according to claim 4 , further comprising a step of dissolving the aggregate by treatment with an acid or a base. A water-soluble polymer having an amino group in the side chain and a linear main chain is represented by the general formula (I)
[Where
R ¹ is C ₁ -C ₃ alkylene,
R ² and R ³ independently of one another are hydrogen or C ₁ -C ₃ alkyl]
And / or the general formula (II)
[Wherein R ⁴ is hydrogen or C ₁ -C ₃ alkyl]
The collection | recovery method in any one of Claims 4-6 which has a structural unit represented by these. The recovery method according to any one of claims 4 to 7 , wherein the amino group is a tertiary amino group. The recovery method according to any one of claims 4 to 8 , wherein the plural kinds of rare earth metal ions are trivalent neodymium ions and trivalent dysprosium ions.