JP3096731B2 - Extraction and separation method for rare earth metal ions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for extracting and separating rare earth metal ions from an aqueous solution containing the same, and more particularly, the present invention relates to a method for preparing a rare earth metal ion-containing aqueous solution having a specific structure. The present invention relates to a method for efficiently extracting the ions in an aqueous solution having a high acid concentration, which has conventionally been difficult to extract and separate, by contacting with an organic solvent containing a compound having the compound, and performing the batch or mutual separation efficiently. .

[0002]

2. Description of the Related Art Rare earth metals are widely used in phosphors, magnets, ceramics, etc., but their separation has been considered difficult, and it has been an issue to increase the efficiency of their mutual separation. Was. In the ordinary separation process, solvent extraction using an alkyl phosphate or alkyl phosphonic acid-based extraction reagent has been generally performed, but when extracting from a highly acidic solution, a sufficient extraction rate cannot be obtained. Or a large amount of reagent must be used to extract a trace amount of rare earth metal ions.

[0003] On the other hand, in the solvent extraction using a synergistic effect to improve the extraction rate of metal ions by adding a neutral organic ligand, the separation coefficient between rare earth metal ions is traded for improvement of the extraction rate. There was a drawback of causing a decrease.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to carry out solvent extraction and separation of a rare-earth metal ion from a high-acid-concentration aqueous solution containing the rare-earth metal ion by a simple operation at once or by mutual separation. It is a thing.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the separation and extraction of rare earth metal ions from an aqueous solution. As a result, a compound having a specific structure has high reactivity with rare earth metal ions. The present invention has been found to have a large separation coefficient between the rare earth metal ions.

That is, the present invention relates to extraction and separation of rare earth metal ions from an aqueous solution containing rare earth metal ions.
A method for contacting the aqueous solution with an organic solvent containing a compound represented by the chemical formula (1) to transfer rare earth metal ions from the aqueous solution to the organic solvent phase in a lump or by mutually separating the ions. is there.

According to the present invention for solving the above-mentioned problems, in extracting a rare earth metal ion from an aqueous solution containing a rare earth metal ion, the aqueous solution is brought into contact with an organic solvent containing a compound represented by the chemical formula (1) to extract the rare earth metal ion. Is a method for extracting and separating rare earth metal ions, which comprises transferring from a water phase to an organic phase.

[0008]

Next, the present invention will be described in more detail. In the present invention, a compound represented by the following chemical formula (1) is used. Here, as R ₁ and R ₂ , specifically, for example, hexyl, heptyl, octyl, decyl, dodecyl, hexadecyl, octadecyl,
Examples include isooctyl, phenyl, 2-ethylhexyl, naphthyl, cyclohexyl and the like. That is, examples of the compound include 1,3-benzenedimethylbis (phenylphosphinic acid) and 1,3-benzenedimethyl.
Bis (octylphosphinic acid) and the like.

[0009]

Embedded image

The compound used in the present invention is 1,
It can be synthesized using 3-bis (bromomethyl) benzene and a suitable alkyl phosphinic acid or aromatic phosphinic acid as raw materials. The reagent thus obtained has two sites that selectively react with the metal ion, and it is possible to form a complex more strongly than a conventional reagent coordinated monodentately.

[0011] Among the compounds represented by the chemical formula (1),
1,3-benzenedimethylbis (phenylphosphinic acid) where R ₁ = R ₂ = phenyl is readily synthesized from 1,3-bis (bromomethylbenzene) and twice as much phenylphosphinic acid as Can be used well in solvent extraction.

In the present invention, it is necessary to dissolve the compound represented by the chemical formula (1) in an organic solvent and bring it into contact with a rare earth metal ion solution.

The organic solvent used at this time is not particularly limited as long as it can dissolve the above-mentioned compound and is not miscible with water, but it is easily available and has high solubility. In this respect, polar solvents such as chloroform, carbon tetrachloride, methyl isobutyl ketone, nitrobenzene and octanol are preferred.

In the solvent extraction, the higher the pH of the aqueous solution containing a rare earth metal ion is, the higher the extraction rate is, but care must be taken since neutral to alkaline causes hydrolysis precipitation. Further, since the extraction reagent has a property of transferring to an aqueous phase when it comes into contact with an alkaline aqueous solution, it is desirable that the liquidity be kept acidic by using an appropriate acid.

If the amount of the reagent in the organic solvent is not sufficient compared with the amount of the rare earth metal ion to be extracted, the extraction rate is reduced, so care must be taken. At least three times, ideally five times or more reagents are required for rare earth metal ions. On the other hand, the extraction ratio tends to increase as the concentration of the reagent increases.

In the present invention, in order to back-extract the rare earth metal ion from the organic solvent from which the rare earth metal ion has been extracted into the aqueous phase, it is effective to use an aqueous solution which is more acidic than that used in the extraction. For example, an acid solution prepared by diluting hydrochloric acid or sulfuric acid is preferably used. The distribution ratio of rare earth metal ions tends to be about 1/1000 each time the pH is decreased by one.

[0017]

EXAMPLES Next, the present invention will be described more specifically based on examples, but the present invention is not limited to the examples. Example 1 It was confirmed that the organic reagent 1,3-benzenedimethylbis (phenylphosphinic acid) was synthesized by the following procedure. Phenylphosphinic acid was mixed with an equal amount of ammonia in alcohol and evaporated to dryness to obtain its ammonium salt. After heating the ammonium salt to 110 ° C. with an excess amount of hexamethyldisilazane in an inert gas,
Solution of xylene bromide in dichloromethane
Heated. After refluxing for 2 hours, the mixture was stirred overnight at room temperature, and a solution in which an excess amount of hydrochloric acid was added to extract the product in dichloromethane was allowed to stand, whereby a precipitate of the target compound was obtained.

Example 2 10 ml of 0.1 mol / l hydrochloric acid aqueous solution containing trivalent lanthanum ion at a concentration of 1 × 10 ⁻⁵ mol / l
Then, 10 ml of a chloroform solution containing 1 × 10 ⁻³ mol / l of 1,3-benzenedimethylbis (phenylphosphinic acid) was added thereto, and the mixture was shaken for 5 minutes to 5 hours to determine the concentration of lanthanum remaining in the aqueous solution by ICP emission. Measured by spectroscopy. As a result, the concentration of lanthanum reached about 3.3 × 10 ⁻⁶ mol / l with 15 minutes of shaking, and the concentration was kept constant until 5 hours later.

Example 3 Trivalent lanthanum ion, trivalent cerium ion, trivalent praseodymium ion, trivalent neodymium ion, trivalent samarium ion, trivalent europium ion, trivalent gadolinium ion, trivalent terbium ion, trivalent dysprosium ion 10 ml of a hydrochloric acid solution containing one of trivalent holmium ion, trivalent erbium ion, trivalent thulium ion, trivalent ytterbium ion and trivalent lutetium ion at a concentration of 1 × 10 ⁻⁵ mol / l Then, 10 ml of a chloroform solution containing 1.times.10.sup. ^-3 mol / l of 1,3-benzenedimethylbis (phenylphosphinic acid) was added thereto, and the mixture was shaken at 25.degree. C. for 30 minutes. The resulting logarithm of the distribution ratio of each metal ion and the p of the aqueous solution
The relationship of H is shown in FIG. The difference in the distribution ratio between the lanthanum-lutetium reached ¹⁰⁵ times, greater resolution is shown.

Example 4 1,3-Trivalent lanthanum ion, trivalent europium ion and trivalent lutetium ion were added to 10 ml of a hydrochloric acid solution containing 1 × 10 ⁻⁵ mol / l in a concentration of 1−3,3. 10 ml of a chloroform solution containing benzenedimethylbis (phenylphosphinic acid) was added, and 25
Shake at 30 ° C. for 30 minutes. The pH of the aqueous phase was 1.6 for trivalent lanthanum ions, 1.1 for trivalent europium ions, and 0.1 for trivalent lutetium ions. FIG. 2 shows the relationship between the resulting logarithm of the distribution ratio of each metal ion and the concentration of the reagent in chloroform. In each of the systems, an increase in the distribution ratio was observed with an increase in the reagent concentration.

[0021] Example 5 trivalent lanthanum ions, 1,3 trivalent gadolinium ions and trivalent lutetium ions in hydrochloric acid solution 10ml of pH0.1 containing a concentration of each 1 × 10 ^-5 mol / liter
A chloroform solution 1 containing 1 × 10 ⁻³ mol / l of benzenedimethylbis (phenylphosphinic acid)
0 ml was added and shaken at 25 ° C. for 30 minutes. As a result, no extraction of trivalent lanthanum ions was observed, and about 17% of trivalent gadolinium ions were extracted, whereas 99% or more of trivalent lutetium ions were extracted.

EXAMPLE 6 1,3 trivalent lanthanum ions, trivalent gadolinium ions and lutetium lutetium ions were added to 10 ml of a hydrochloric acid acidic solution at a pH of 1.1 containing 1 × 10 ⁻⁵ mol / l each.
A chloroform solution 1 containing 1 × 10 ⁻³ mol / l of benzenedimethylbis (phenylphosphinic acid)
0 ml was added and shaken at 25 ° C. for 30 minutes. As a result, about 34% of trivalent lanthanum ions were extracted, while trivalent gadolinium ions and trivalent lutetium ions were completely extracted.

Example 7 1,3 trivalent lanthanum ions, trivalent gadolinium ions and lutetium lutetium ions were added to 10 ml of a hydrochloric acid acidic solution having a pH of 2.1 containing 1 × 10 ⁻⁵ mol / l each.
A chloroform solution 1 containing 1 × 10 ⁻³ mol / l of benzenedimethylbis (phenylphosphinic acid)
0 ml was added and shaken at 25 ° C. for 30 minutes. As a result, all metal ions were completely extracted, and no residual metal was observed in the aqueous solution.

[0024]

According to the present invention, trivalent rare earth metal ions can be well separated and extracted in a low pH range. It is also possible to simultaneously extract all trivalent rare earth metal ions by increasing the pH. The method of the present invention is useful, for example, as a method for mutually separating or simultaneously extracting and recovering rare earth metals under conditions of high acid concentration. The method can also be applied to analytical chemical metal ion separation.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the pH and the distribution ratio of metals when rare earth metal ions are extracted by changing the pH of an aqueous phase in the present invention.

[Explanation of symbols]

La: lanthanum, Ce: cerium, Pr: praseodymium, Nd: neodymium, Sm: samarium, Eu: europium, Gd: gadolinium, Tb: terbium, D
y: dysprosium, Ho: holmium, Er: erbium, Tm: thulium, Yb: ytterbium, Lu:
lutetium.

FIG. 2 is a graph showing a relationship between a reagent concentration and a distribution ratio of a metal when a rare earth metal ion is extracted by changing a reagent concentration of an organic phase in the present invention.

[Explanation of symbols]

La: lanthanum, Eu: europium, Lu: lutetium.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-160820 (JP, A) JP-A-9-3082 (JP, A) JP-A-53-142311 (JP, A) JP-A-60-1985 251126 (JP, A) JP-A-5-147932 (JP, A) JP-A-7-26336 (JP, A) JP-A 9-176757 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22B 59/00 B01D 11/04 C22B 3/26

Claims (1)

(57) [Claims] When extracting and separating a rare earth metal ion from an aqueous solution containing a rare earth metal ion, the aqueous solution is subjected to the chemical formula (1). A method for extracting and separating rare earth metal ions from an aqueous phase by contacting the rare earth metal ions with an organic solvent containing a compound represented by formula (1).