JP2014148738A - Method of separating and recovering rare earth elements and acid from solution containing rare earth elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem related to recovery of rare earth elements that, because conventional methods of recovering rare earth elements based on solvent extraction require complicated equipment owing to use of large amounts of solvents and an acid, possible troubles from a viewpoint of saving of resources and energy, and allow only specified large enterprises to introduce and perform them owing to expensiveness for small and medium-sized enterprises, a method of collecting rare earth elements efficiently from a solution containing rare earth elements, separating individual metal ions, with high purity, from the collected material and recovering acids used is awaited.SOLUTION: A method of separating and recovering rare earth elements and an acid comprises producing an extraction reagent supporting adsorbent material by a radiation graft polymerization method, bringing a liquid containing a plurality of rare earth elements into contact with the extraction reagent supporting adsorbent material to make the rare earth elements to be adsorbed, bringing the extraction reagent supporting adsorbent material into contact with an acid of 0.5 N or lower to elute light rare earth elements and then with an acid of 0.5 N or higher to elute heavy rare earth elements and recovering the acid in the elution by using an electrodialyzer and simultaneously recovering rare earth elements of a decreased concentration of the acid.

Description

  The present invention relates to a rare earth element from a solution obtained by acid-treating a solution in which a rare earth element is eluted with acid from cutting powder and scrap generated from the manufacturing process of the product containing the rare earth element or an acid treatment for recovering the rare earth element in the waste product. The present invention relates to a separation and recovery method for separating and recovering acid and acid.

  In recent years, rare earth magnets are widely used in various motors and sensors used in HDDs, air conditioners, mobile phones and the like.

  The price of rare earth elements, which are raw materials, is rising in China because of their political origins. Therefore, there is a strong demand for recovering and recycling valuable materials from magnet powder, scraps and defective scrap generated during the production of products using rare earth elements.

  As a method for recovering rare earth elements, Japanese Patent Application Laid-Open No. 62-83433 (Patent Document 1) discloses a rare earth element salt obtained by heating a rare earth element-iron-containing alloy by air oxidation and then using an acid elution method using a strong acid. Is dissolved in a filtrate, and separated by filtration.

In JP-A-01-183415 (Patent Document 2), scraps of rare earth magnets and the like are dissolved in acid (HCl) to separate and remove insoluble residues, and an oxidizing agent (HNO ₃ ) is added, and an oxalic acid solution is added. In addition, it is disclosed that the rare earth element is precipitated as oxalate by adjusting to a predetermined pH.

  In Japanese Patent Application Laid-Open No. 05-287405 (Patent Document 3), a slurry is maintained with an acid at a pH of 3 to 5 in the presence of an oxidizing agent to selectively leach rare earth elements, and the resulting leachate contains alkali carbonate or carbonic acid. A method is disclosed in which a hydrogen alkali is added to separate a rare earth element as a sparingly soluble salt in water.

  In Japanese Patent Application Laid-Open No. 09-217132 (Patent Document 4), while circulating air in a slurry, a dilute nitric acid solution is added to maintain the pH at 5 or higher, and a metal containing rare earth and cobalt is dissolved at 50 ° C. or lower. A method of separating by filtration from an insoluble element compound containing iron, and adding a fluorine compound or oxalic acid to the rare earth-containing nitrate solution to precipitate a rare earth fluoride or rare earth oxalate, and a cobalt-containing nitric acid solution And a method of separating by filtration.

  Japanese Patent Application Laid-Open No. 11-100522 (Patent Document 5) discloses a method for separating and extracting rare earth element ions with a solvent containing an extraction reagent bis (2-ethylhexyl) phosphinic acid at a pH of 3 or higher in an aqueous solution containing neodymium or yttrium ions. Is disclosed.

  Japanese Patent Laid-Open No. 2005-331510 (Patent Document 6) is composed of the same inventors as the inventors of the present application. There is a disclosure of a material in which a functional group having a function of carrying an extraction reagent is introduced into a graft polymer chain that has been subjected to radiation graft polymerization on a base material. In the examples, an example of separating yttrium from a nitric acid solution is described.

  However, these methods are focused on recovering only rare earth elements. A large amount of acid and alkali for neutralizing it was consumed, and improvement was demanded from the viewpoint of resource saving and energy saving. In addition, a large amount of solvent and back-extraction solvent are consumed in the solvent extraction method used for separating rare earth from a liquid containing a plurality of rare earth elements. Further, Patent Document 6 discloses an extraction reagent carrying material using a radiation graft polymerization method and yttrium ion separation using the same, but each metal ion is separated from the extraction reagent carrying material adsorbing a plurality of rare earth ions. There is no disclosure about the recovery of the acid used for separation.

JP-A-62-83433 Japanese Patent Laid-Open No. 01-183415 JP 05-287405 A JP 09-217132 A Japanese Patent Laid-Open No. 11-100522 JP 2005-331510 A

  The present invention is a problem of the conventional recovery method, that is, it efficiently collects rare earth elements from a solution containing a plurality of types of rare earth elements, separates each metal ion from the collected materials, and uses the acid used for elution. It is an object to provide a collection method that can be collected and reused.

  As a result of intensive studies aimed at solving the above problems, the present inventors have found a method for separating and recovering a rare earth element and an acid having the characteristics shown in the following (1) to (6), and the present invention Reached.

(1) A method for separating and recovering two or more rare earth elements including light rare earth and heavy rare earth from a liquid containing rare earth elements, wherein the liquid containing the rare earth elements is brought into contact with the extraction reagent-carrying adsorbing material. Two types, including a first step of adsorbing rare earth elements, a second step of elution of light rare earth by bringing a thin acid into contact with the adsorbed adsorbent, and a third step of elution of heavy rare earth by contacting a dense acid Method for separating and recovering acid and rare earth element from a liquid containing the above rare earth element

(2) The liquid after the rare earth is adsorbed in the first step is treated with an acid recovery device to recover the acid, and the acid eluent obtained in the second step is processed with an acid recovery device. The acid eluent obtained in the fifth step and the third step of collecting the rare earth element solution having a reduced acid concentration simultaneously with the recovery of the acid is treated with an acid recovery device, and the rare earth having the acid concentration reduced simultaneously with the recovery of the acid. A method for separating and recovering an acid and a rare earth element from a liquid containing two or more kinds of rare earth elements according to claim 1, comprising a sixth step of recovering the solution.

(3) The acid recovery device is an electrodialysis device, and includes recycling the recovered acid in a step selected from the acid dissolution step, the second step, and the third step before the first step. A method for separating and recovering an acid and a rare earth element from a liquid containing two or more kinds of rare earth elements according to claim 1 or 2.

(4) The two or more rare earth elements according to claim 1, 2 or 3, wherein the thin acid used in the second step is 0.5 N or less and the acid used in the third step is 0.5 N or more. For separating and recovering acid and rare earth elements from liquids containing oxygen

(5) Means selected from the above-described rare earth element solution having a reduced acid concentration obtained in the second step and the third step by adsorption fixing with a chelate resin, precipitation as oxalate, and precipitation as hydroxide. A method for separating and recovering rare earth elements from a liquid containing two or more kinds of rare earth elements according to claim 1, 2, 3, or 4

(6) The extraction reagent carrying material is
A. The substrate is a polymer particle, porous hollow fiber, membrane, fiber, fabric, non-woven fabric, porous polymer substrate,
A. A polymerizable monomer selected from glycidyl methacrylate or glycidyl acrylate, hydroxyl methacrylate, vinyl pyrrolidone, dimethyl acrylamide, ethylene glycol dimethacrylate, alkyl methacrylate, or alkyl acrylate is graft polymerized by radiation graft polymerization.
C. A functional group having an extraction reagent supporting function selected from an alkyl group, an alkanol group, an alkanolamino group, an alkylamino group, an epoxy group, and a diol group is introduced into the graft side chain,
D. A material produced by loading an extraction reagent selected from bis (2-ethylhexyl) phosphate, bis (2,4,4-trimethylpentyl) phosphinic acid, trioctylmethylammonium chloride as an extraction reagent (1), (2), (3), (4) or (5) a method for separating and recovering rare earth elements from a liquid containing two or more kinds of rare earth elements

  The present inventors have developed a material capable of removing malodors such as ammonia and organic acids and harmful metals in water by using a radiation graft polymerization method. A material having the following characteristics is disclosed in the extraction reagent carrying material described in JP-A-2005-331510.

  Hydrophobic material that is a material in which a functional group having a function of carrying an extraction reagent is introduced into the graft polymer chain attached to the fiber substrate, and serves as a tie for carrying the extraction reagent on the graft polymer chain such as glycidyl methacrylate And an extraction reagent such as bis (2-ethylhexyl) phosphate (HDEHP) is supported.

  The same material is used in this patent, but among rare earth elements, a solution containing a plurality of types of light rare earth (atomic number smaller than gadolinium) and heavy rare earth (atomic number larger than gadolinium) is treated. Adsorb rare earth ions.

  The light rare earth is eluted with a thin acid of 0.5 N or less, and the heavy rare earth is eluted with a thick acid of 0.5 N or more. By contacting the two kinds of acids in the light and dark with the column packed with the extraction reagent-carrying material, 99% or more of the adsorbed two kinds of rare earths can be eluted, and each metal can be separated and recovered with a purity of 99% or more. . Although a batch process may be used, a column system can be suitably applied.

  For easy understanding, an example of a rare earth magnet containing Nd (neodymium) and Dy (dysprosium) will be described. Waste magnets collected from cutting scraps and waste magnet products generated from the manufacturing process of rare earth magnets are obtained as Nd and Dy-containing solutions by dissolving hydrochloric acid or the like. Here, iron is a main component of the magnet, but since the oxide is generated by high-temperature oxidation treatment in the demagnetization process, elution into hydrochloric acid is suppressed. Therefore, Nd and Dy are eluted relatively easily with a relatively low concentration of hydrochloric acid of 0.5 N or less.

  Nd and Dy dissolved in the hydrochloric acid solution are adjusted to pH and acidified to about pH 2, and then contacted with HDEHP-supporting fibers and adsorbed. Then, Nd can be eluted by contacting with 0.1 N to 0.5 N hydrochloric acid, for example, 0.2 N thin acid. Dy elutes upon contact with 0.5 N hydrochloric acid or more, for example, 1.5 N hydrochloric acid. Thereby, Nd and Dy can be separated. Here, if iron is present, it is adsorbed to the HDEHP-supporting fiber, so it is necessary to remove it below a predetermined concentration. For example, the prior art can be used, such as adjusting the pH with an alkali or the like and removing the precipitate with an iron hydroxide.

  Acid after hydrochloric acid solution containing Nd and Dy was adsorbed on HDEHP-supported fiber, 0.5N or less thin acid used to elute Nd and 0.5N used to elute Dy By processing the above concentrated acid with an electrodialyzer, an acid having a predetermined concentration, an Nd solution having a reduced acid concentration, and a Dy solution having a reduced acid concentration can be obtained.

  The recovered acid can be reused to dissolve waste magnets and cutting waste. Further, it can be reused for elution of HDEHP resin, and resource saving can be achieved. Further, when the Nd solution having a reduced acid concentration is neutralized with an alkali and reduced in volume and solidified as a hydroxide, the amount of alkali consumed is reduced, and resource saving can be achieved. The same applies to the Dy solution. When the Nd and Dy solutions are brought into contact with oxalic acid and transferred to the next step as an oxalic acid precipitate, the amount of washing water for the precipitate is reduced, which is convenient. Further, when the Nd and Dy solution is treated with an adsorbent such as an ion exchange resin or a chelate resin, the adsorption capacity can be increased by reducing the acid concentration.

  FIG. 1 shows a basic flow of a treatment process for recovering rare earth elements and acids according to the present invention. Although hydrochloric acid is used as the acid, other acids may be used. A hydrochloric acid solution containing Nd and Dy is passed through a column filled with an extraction reagent-carrying adsorbent, and the treatment liquid from which Nd and Dy have been adsorbed and removed is stored in a treatment liquid tank. When the predetermined amount of adsorption is completed, a thin hydrochloric acid of about 0.2 N is passed through to elute Nd. Then, concentrated hydrochloric acid of about 1.5 N is passed through to elute Dy. The hydrochloric acid eluent containing Nd is treated with an electrodialyzer and separated into hydrochloric acid from which Nd has been removed and Nd solution having a reduced hydrochloric acid concentration. The concentrated hydrochloric acid eluent containing Dy is also treated with an electrodialysis apparatus, and separated into concentrated hydrochloric acid from which Dy has been removed and Dy solution having a reduced hydrochloric acid concentration. Further, the recovered acid can be returned to the upstream of the illustrated flow and used to dissolve the waste magnet. In addition, when the concentration of hydrochloric acid or iron is high, it can be treated with an electrodialyzer before adsorbing with the extraction reagent-carrying material and separated from Nd and Dy as an iron chloro complex.

  FIG. 2 shows a principle diagram of electrodialysis, but is not limited to the scope of this figure. The liquid 5 containing hydrochloric acid, Nd, and Dy enters the desalting chamber 7, and the chlorine ions pass through the anion exchange membrane 1 to the concentration chamber 8 on the anode side, and Nd and Dy pass through the cation exchange membrane 2, Enter the concentration chamber on the cathode side. Here, a monovalent ion selective membrane can be used for the cation exchange membrane. In that case, Nd and Dy can be recovered from the outlet 6 of the desalting chamber. Which ion exchange membrane is used can be appropriately determined depending on the type of metal to be recovered and the use conditions. Since boron does not dissociate in an acidic solution, it does not pass through both ion exchange membranes and comes out from the desalting chamber outlet 6.

  The recovery flow of the present invention can be either a continuous type or a batch type, but batch processing is suitable if the amount of the liquid containing the rare earth element is not large. In that case, the acid and metal mixed solution generated in each step can be processed with one electrodialyzer, and the acid suitable for each step can be recovered. Of course, an electrodialysis apparatus suitable for each process may be installed separately. FIG. 1 shows one example.

  When the adsorbent is in the form of particles, it can be packed in an adsorption tower and a flow process method can be employed. Although a fibrous material can also be filled in the adsorption tower, for example, in the case of a fiber or sponge-like void material, the adsorbent may be suspended as shown in FIG. 3 and moved between treatment tanks corresponding to the respective steps.

  In FIG. 3, an adsorbent material such as a molding (such as a car wash brush), non-woven fabric, sponge, cotton lump, cut fiber or the like is stored in a container as it is or depending on use conditions, and is passed through a rail. Can be moved. Equipment can be simplified by combining the adsorbent's up-and-down movement with stirring operation in adsorption and elution operations.

  After performing acid recovery using an electrodialyzer, the rare earth element solution has a reduced acid concentration and can be re-adsorbed using a chelating group such as an iminodiacetic acid group or an aminophosphoric acid group. Since the acid concentration is lowered, the adsorption capacity is preferably increased. Moreover, the chemical | medical agent required for neutralization and washing | cleaning can be reduced also when producing | generating precipitation with an oxalic acid or sodium hydroxide.

  The extraction reagent-carrying material used in the present invention is based on an organic polymer having a large surface area such as a fiber, sponge or porous membrane by a radiation graft polymerization method. In addition, the graft chain grows not only inside the substrate but also outside the substrate. It is advantageous for supporting the extraction reagent.

  The radiation graft polymerization method is a method of irradiating a substrate with ionizing radiation such as γ-rays or electron beams and utilizing a radical generated on the surface of the substrate or inside the substrate (hereinafter referred to as “monomer”). Is a method of growing a graft chain from a substrate. As the ionizing radiation used in the radiation graft polymerization method, alpha rays, beta rays, gamma rays, electron rays, ultraviolet rays, and the like can be used. Industrially available gamma rays and electron rays are suitable for the present invention.

  Although the length of the graft side chain depends on the graft ratio, it usually ranges from several to several hundreds of ethylene units (molecular weight of several tens of thousands or more). In addition, as the graft is translated as “grafting”, one end of the polymer chain is bonded to the main chain, and the other end is a free end, so an alkyl group or alkanol group that plays a role in linking with the extraction reagent. It is advantageous to introduce etc. Therefore, it is advantageous for carrying the extraction reagent.

The organic polymer that can be used in the radiation graft polymerization method can be selected from various types. For example, taking fibers as an example, in addition to synthetic fibers, cellulosic fibers such as cotton, animal fibers, mineral fibers, regenerated fibers, or mixed fibers thereof may be mentioned. Synthetic fibers include polyester, polyamide, acrylic, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyurethane, polyvinyl alcohol, fluorine, and the like. Cellulosic fibers include natural cellulose fibers such as cotton and hemp, viscose rayon, copper ammonia rayon, regenerated cellulose fibers such as polynosic, purified cellulose fibers such as tencel, and semi-synthetic fibers such as acetate and diacetate. It is. Animal fibers include animal hair fibers such as wool, silk and the like. The recycled fiber includes chitin / chitosan fiber, collagen fiber and the like. It is also possible to use blends of these fiber materials.
In addition to fibers, void materials such as hollow fiber membranes, films and sponges can also be used.

  There are a pre-irradiation graft polymerization method and a simultaneous irradiation graft polymerization method depending on the timing at which the substrate is irradiated with radiation. Either polymerization method can be used. The former performs graft polymerization by irradiating a substrate with radiation and then contacting with a monomer. In the latter, irradiation is performed in a state where the substrate and the monomer are present simultaneously. Any method can be adopted, but the pre-irradiation graft polymerization method with a small amount of homopolymer is preferable as the separation material.

  In addition, a liquid phase graft polymerization method in which the graft polymerization is performed in a monomer liquid, a gas phase graft polymerization method in which the monomer is vaporized, an impregnation gas phase grafting in which an amount of the monomer to be grafted is added and then reacted in an inert gas. Any graft polymerization method such as a polymerization method can be used.

  The monomer for graft polymerization can be selected from those that can easily introduce an alkyl group, an alkanol group, an alkanolamino group, an alkylamino group, an epoxy group, a diol group, and a thiol group for supporting an extraction reagent. Monomers selected from glycidyl methacrylate or glycidyl acrylate, hydroxyl ethyl methacrylate, vinyl pyrrolidone, dimethyl acrylamide, ethylene glycol dimethacrylate, alkyl methacrylate, or alkyl acrylate are preferred. In particular, glycidyl methacrylate or glycidyl acrylate is suitable.

  When an alkyl group is introduced after graft polymerization of these monomers, for example, a drug having an alkylamino group is introduced. Agents with amino groups that are easy to introduce into the graft polymer and have excellent extraction reagent loading ability include linear amines such as ethylamine, butylamine, pentylamine, dodecylamine, octadecylamine, dimethylamine, diethylamine, and triethylamine. Etc. are also available. Also, amines having a plurality of amino groups such as ethylenediamine and hexamethylenediamine can be used. Piperazine, 1,4 diazabicyclo [2.2.2] octane and the like can also be used. Furthermore, amines such as diethylenetriamine, triethylenetritetramine, and polyethyleneimine can be used.

  Among them, when the carbon number of the alkyl group is larger than 20, the hydrophobicity increases, so that the graft chains attract each other and the space necessary for carrying the extraction reagent cannot be maintained, so that the adsorption performance is sufficiently exhibited. Can not. In addition, when the number of carbon atoms is 1, the hydrophobic portion is small, so that the hydrophobic interaction is small, and the amine odor is strong, which is a problem in the working environment. 2 or more carbon atoms are preferred.

  Alkanolamines can be used in the same manner as in the case of amines. Monoethanolamine and diethanolamine can be preferably used. Since it has a hydroxyl group, its hydrophilicity increases, but its boiling point is very high, and environmental problems due to the generation of amine odor are reduced.

  As a combination of an extraction reagent and a functional group having a supporting function, a combination of bis (2-ethylhexyl) phosphate (HDEHP) and octadecylamino group, a combination of bis (2-ethylhexyl) phosphate and dodecylamino group, bis (2 , 4,4-Trimethylpentyl) phosphinic acid and octadecylamino group, bis (2,4,4-trimethylpentyl) phosphinic acid and dodecylamino group, trioctylmethylammonium chloride and 6-aminohexanoic acid group Combinations, combinations of trioctylmethylammonium chloride and octadecylamino groups and 6-aminohexanoic acid groups, combinations of tri-n-octylphosphine oxide and octadecanethiol groups, and the like can be mentioned. The combination can be appropriately selected depending on the type of recovered metal, usage environment, production conditions, and the like.

  The present invention relates to an extraction reagent carrying material produced by using a radiation graft polymerization method and a method for separating and recovering an acid and a rare earth element from an acidic liquid containing two or more kinds of rare earth elements using the same. It is characterized by separating and collecting two kinds of rare earth elements, earth and heavy rare earth, and acid.

  Not only rare earth elements but also process scraps and used waste products generated from the manufacturing process of products using rare metals contain useful metals. In order to recover them, first, a useful metal-containing solid is pulverized by physical treatment, dissolved using hydrochloric acid or nitric acid, and then useful metals are separated and recovered from the solution. The present invention can be applied to such places, and the separation efficiency of useful metals can be dramatically increased and the amount of chemicals used can be greatly reduced. The amount of waste generated can also be reduced.

  In addition, various adsorbents such as activated carbon, ion exchange resin, chelate resin, zeolite, etc. consume a large amount of acid to regenerate after use, but recover acid from such waste liquid, not only useful metals but also harmful Concentration and volume reduction of metal ions can be achieved. Provide useful metal separation and acid recovery processes that meet social requirements for resource conservation, energy conservation and safety.

  By using the extraction reagent supporting material proposed by the present invention, light rare earth and heavy rare earth can be almost completely separated and recovered from a plurality of rare earth mixed acid solutions of light rare earth and heavy rare earth, and acid can be recovered. Can do. Since the radiation graft polymerization method can be applied to substrates having various shapes, the usage method can also make use of the characteristics of the substrate shape. Conventionally, the rare earth element recovery process requires a complex plant such as a dissolution tank, an extraction tank, a pump, and piping, and requires a large amount of capital investment. The present invention also enables a process in which the adsorbent itself can move between the treatment tanks, centering on the electrodialysis apparatus which is an elemental technology, and the apparatus cost can be greatly reduced. Easy to introduce to small and medium manufacturers.

  The preparation of an extraction reagent carrying material using the radiation graft polymerization method of the present invention, adsorption of a rare earth element solution using the material, elution with an acid, and the results of acid recovery from the eluent will be described in detail with examples. This example shows some examples of the present invention, and is not limited to this range.

(Manufacture of extraction reagent carrying material 1)
1 kg of twisted nylon fiber having a diameter of about 25 μm was irradiated with gamma rays in a nitrogen atmosphere. The irradiation dose was 30 kGy. This fiber was immersed in a 10% methanol solution of glycidyl methacrylate previously bubbled with nitrogen, and graft polymerization was performed at 40 ° C. After 6 hours, it was taken out, washed with dimethylformamide and acetone in this order and dried. The weight after drying was measured, and the weight increase rate (graft rate) was calculated to be 83%. The fiber after graft polymerization was immersed in a 20% isopropyl alcohol solution of dodecylamine and reacted at 80 ° C. for 5 hours. A fiber into which 1.5 mmol / g of dodecylamine was introduced was produced from the weight increase rate. Next, this fiber was cut into about 1 cm, immersed in a 60% HDEHP 20% methanol solution, and reacted for 3 hours. From the weight increase rate, an extraction reagent-carrying material on which HDEHP was carried at 0.4 mmol / g was produced.

(Nd, Dy adsorption experiment 1)
2 g of HDEHP-supporting fibers were packed to an inner diameter of 10 mm so that the layer height was 100 mm. A liquid containing Nd 290 mg / l and Dy 40 mg / l and adjusted with hydrochloric acid so that the pH was 2 was passed through the column at a flow rate of 1.3 ml / min. After passing 2 L, it was confirmed that both Nd and Dy were almost the same as the concentration in the liquid to be treated.

(Hydrochloric acid elution 1)
After the Nd and Dy adsorption, 2000 ml of 0.2N hydrochloric acid solution was passed through the extraction reagent-carrying material, and then 2000 ml of 1.5N hydrochloric acid solution was passed. The elution waste solution was sampled from the column outlet every predetermined time, and the concentrations of Nd and Dy were measured with an ICP emission spectroscopic analyzer (manufactured by Perkin Elmer, OPTIMA 8300 DV). The elution curves for Nd and Dy are as shown in FIG. 5, and a separation of 99% or more was achieved.

(Acid recovery by electrodialysis machine 1)
A hydrochloric acid elution waste solution in which Nd was eluted with 0.2 N hydrochloric acid was treated with a microacylator S3 type (manufactured by Astom Co., Ltd.) to recover 2050 ml of 0.2 N hydrochloric acid. Next, 1.5N hydrochloric acid elution waste solution was treated to recover 2200 ml of 1.3N hydrochloric acid. The recovered hydrochloric acid could be reused with only a slight adjustment in concentration. A weakly acidic Nd solution and a Dy solution having a pH of about 3 were recovered.

(Manufacture of extraction reagent carrying material 2)
In Example 1, HDEHP extraction was performed under the same conditions except that a heat-sealed nonwoven fabric having a basis weight of 40 g / m ² and a thickness of 0.3 mm made of polyethylene (sheath) / polyethylene terephthalate (core) having a diameter of 15 μm was used instead of nylon fiber. A reagent-carrying material was produced. This nonwoven fabric carried 0.35 mmol / g of HDEHP from the weight increase rate.

(Nd, Dy adsorption experiment 2)
Ten pieces of HDEHP-supporting nonwoven fabric cut into 10 cm square were produced. This nonwoven fabric was immersed in 1 L of a pH 2 hydrochloric acid solution containing 270 mg / l of Nd and 35 mg / l of Dy and stirred for 30 minutes. The nonwoven fabric was taken out with tweezers and drained. The Nd and Dy concentrations remaining in the solution were 5 mg / L and 1 mg / L, respectively, and 97% or more was adsorbed on the extraction reagent supporting material.

(Hydrochloric acid elution 2)
After adsorption of Nd and Dy, the extracted extraction reagent support material was immersed in a beaker containing 1 L of 0.2 N hydrochloric acid and stirred for 30 minutes. After 30 minutes, the extraction reagent-carrying material was taken out with tweezers and drained. Next, the extraction reagent supporting material was immersed in a beaker containing 1 L of 1.5 M hydrochloric acid and stirred for 30 minutes. After completion of the stirring, the extraction reagent-carrying material was taken out with tweezers, drained and immersed in 1 L of pure water for cleaning. The 0.2 N hydrochloric acid beaker contained Nd of 250 mg / l, and the 1.5 N hydrochloric acid beaker contained 33 mg / L of Dy.

(Acid recovery by electrodialysis machine 2)
The elution waste solution was treated with an electrodialysis apparatus in the same manner as in Example 1, and 1 L of 0.2 N hydrochloric acid and 1.05 L of 1.4 N hydrochloric acid were recovered. The recovered hydrochloric acid could be reused with only a slight adjustment in concentration. A weakly acidic Nd solution having a pH of about 3 and a weakly acidic Dy solution were recovered.

(Creation of chelating fibers for Nd and Dy adsorption)
An iminodiacetic acid group was introduced into the nylon fiber graft-polymerized with glycidyl methacrylate of Example 1 under the following conditions. A solution for introducing iminodiacetic acid groups having a liquid composition of sodium iminodiacetate / isopropyl alcohol / water = 20/40/40 was prepared. The graft fiber was immersed in this solution, and iminodiacetic acid groups were introduced at a reaction temperature of 80 ° C. and a reaction time of 24 hours. From the weight increase after the reaction, 1.8 mmol / g iminodiacetic acid group was introduced.

  5 g of the iminodiacetic acid group-introduced fiber prepared above was immersed in 500 ml each of a pH 3 Nd solution (concentration 250 mg / l) and a Dy solution (concentration 33 mg / l) and stirred for 1 hour to adsorb Nd and Dy. The fibers after adsorption were taken out with tweezers, and the Nd and Dy concentrations remaining in the solution were measured. As a result, Nd was 3 mg / l and Dy was 0.2 mg / l. It was suggested that there is.

: Basic flow of the process for recovering rare earth elements and acids of the present invention : Principle of electrodialysis machine : Flow showing the treatment process to move the adsorbent : Synthesis route of the extraction reagent carrying material of the present invention : Nd and Dy acid elution curves

1. 1. anion exchange membrane 2. Cation exchange membrane 3. Acid recovery solution 4. Metal recovery solution 5. Liquid to be treated Treatment liquid7. Desalination chamber8. Concentration chamber 9. Polar chamber 11. Extraction reagent carrying material 12. Electrodialyzer 13. Adsorption tank 14. First elution tank 15. Second elution tank 16. Washing tank

Claims (6)

  A method for separating and recovering two or more kinds of rare earth elements including light rare earth and heavy rare earth and an acid from an acidic liquid containing rare earth elements, wherein the liquid containing the rare earth elements is brought into contact with the extraction reagent-supporting adsorbing material. Includes a first step of adsorbing rare earth elements, a second step of eluting light rare earth elements by passing a thin acid through an adsorbed adsorbent, and a third step of eluting heavy rare earth elements by passing a thick acid. Method for separating and recovering acid and rare earth element from acidic liquid containing two or more kinds of rare earth elements   The acid after the rare earth element is adsorbed in the first step is treated with an acid recovery device to recover the acid, and the acid eluent obtained in the second step is treated with an acid recovery device to remove the acid. The acid eluent obtained in the fifth and third steps of collecting the rare earth element solution having a reduced acid concentration at the same time as being recovered is treated with an acid recovery device, and the acid is recovered and the rare earth element solution having a reduced acid concentration at the same time. A method for separating and recovering an acid and a rare earth element from an acidic liquid containing two or more kinds of rare earth elements according to claim 1, comprising a sixth step of recovering the acid   2. The acid recovery apparatus according to claim 1, wherein the acid recovery apparatus is an electrodialysis apparatus, and the recovered acid is reused in a process selected from the acid dissolution process, the second process, and the third process preceding the first process. Or a method for separating and recovering an acid and a rare earth element from an acidic liquid containing two or more rare earth elements according to 2   The thin acid used in the second step is 0.5 N or less, and the acid used in the third step is 0.5 N or more, containing two or more rare earth elements according to claim 1, 2 or 3. Method for separating and recovering acid and rare earth elements from acidic liquid   Reduced volume of the rare earth element solution with reduced acid concentration obtained in the second and third steps by means selected from adsorption fixation with chelate resin, precipitation as oxalate and precipitation as hydroxide. A method for separating and recovering a rare earth element from an acidic liquid containing two or more kinds of rare earth elements according to claim 1, 2, 3, or 4 The extraction reagent carrying material is
[1] The substrate is a porous hollow fiber membrane, a fiber, a fabric, a nonwoven fabric, or a porous polymer substrate,
[2] A polymerizable monomer selected from glycidyl methacrylate or glycidyl acrylate, hydroxyl methacrylate, vinyl pyrrolidone, dimethylacrylamide, ethylene glycol dimethacrylate, alkyl methacrylate, or alkyl acrylate is graft-polymerized by radiation graft polymerization,
[3] A functional group having an extraction reagent carrying function selected from an alkyl group, an alkanol group, an alkanolamino group, an alkylamino group, an epoxy group, a diol group, and a thiol group is introduced into the graft side chain,
[4] Material manufactured by supporting an extraction reagent selected from bis (2-ethylhexyl) phosphate, bis (2,4,4-trimethylpentyl) phosphinic acid, and trioctylmethylammonium chloride as an extraction reagent A method for separating and recovering rare earth elements from a liquid containing two or more rare earth elements according to claim 1, 2, 3, 4, or 5.

Images