JPS6050855B2 - How to isolate yztrium - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for separating yttrium.

Yttrium is in strong demand as an industrial raw material, mainly in the electronics field, as a raw material for red phosphors for color televisions and as a material for optical lenses. Conventionally,
The ion exchange method is known as a method for separating yttrium from a mixed aqueous solution of red clay containing yttrium, but since this method treats red clay as an extremely dilute aqueous solution, the concentration of the purified yttrium aqueous solution becomes small and it becomes concentrated. In addition to requiring large-scale equipment, the flow rate of the eluent flowing through the ion exchange resin column is low, resulting in low productivity.

A method for separating yttrium by solvent extraction has been proposed as a method for improving the drawbacks of the above-mentioned ion exchange method.

For example, a method for separating yttrium from heavy red iron in the presence of thiocyanine ions using a quaternary ammonium salt as an extraction solvent (Japanese Patent Publication No. 45-432 & Patent Publication No. 49-1038
15), or a method for selectively extracting yttrium from a red clay nitrate aqueous solution containing yttrium using a mixed solvent of a cation exchange solution and an anion exchange solution (USP
3, 575, 687), etc. However, the former method is prone to decomposition of thiocyanine ions and is troublesome in terms of operational management.Furthermore, all of the above methods have a small separation coefficient between yttrium and other red clays (2
~3) In order to obtain high-purity yttrium, several dozen stages of extraction must be performed. Also, the Bureau of Mines, Report, of Investments.
6396(1)
964) Pages 10 to 16 state that in a method for extracting and separating red clay from a red clay aqueous solution using naphthenic acid as an extraction solvent, the separation coefficient between each red clay can be improved by the presence of a chelating agent in the red clay aqueous solution phase. is listed.

Specifically, the use of ethylenediaminetetraacetic acid (hereinafter referred to as EDTA) as a chelating agent improves the separation coefficient between heavy rare earths), and the use of diethylenetriaminepentaacetic acid (hereinafter referred to as DTPA) improves the separation coefficient between light rare earths. It has been shown that the coefficient and the separation coefficient between yttrium and heavy red matter are improved. However, in the above extraction system, ion exchange between the heavy Akashima ions in the extraction solvent and the yttrium ions in the Akaji aqueous solution phase does not substantially occur, so a back-extraction operation must be performed each time one stage of extraction is performed. Therefore, it cannot be applied to a countercurrent multistage continuous extraction method using a mixer-settler type extractor or an extraction column.

As a result of intensive studies to develop a solvent extraction method for yttrium that is industrially more advantageous than the conventional techniques, the present inventors found that ethylenediamine-N,N'' is used as a complexing agent.
- diacetic acid (hereinafter referred to as EDDA).

) is present in an aqueous solution of heavy rare earth containing yttrium, and extraction is performed using a carboxylic acid-based extraction solvent. The present invention was achieved by discovering that it can be separated from heavy rare earths. The present invention will be explained in detail below.

In addition to yttrium, the present invention uses rare earths having an atomic number of 66 to 71 (hereinafter referred to as heavy rare earths).

) is applied when separating yttrium from a rare earth mixture containing at least one of the following. These rare earths are naturally produced as monazite, xenotime, etc., but xenotime is mainly used as a raw material for the purpose of obtaining yttrium. In the method of the present invention, when such ores or rare earth mixtures containing light rare earths are used as raw materials, it is necessary to separate and remove rare earths with atomic numbers of 57 to 65 in advance by a well-known method. . For example, a rare earth mixture is made into an aqueous solution, and an acidic phosphoric acid ester such as di-2-ethylhexyl phosphoric acid is used as an extraction solvent.
Yttrium and heavy rare earth can be extracted while leaving the rare earth of No. 5 in the aqueous solution. These yttrium and shield rare earth extracted with the extraction solvent can be obtained as an aqueous solution by back extraction with a mineral acid such as nitric acid or hydrochloric acid. Such as yttrium and! EDDA is added and dissolved in an aqueous solution containing heavy rare earth, and the concentration and pH of each component are determined.
is prepared and used as a extract in the method of the present invention.
The concentration of rare earth contained in the extracted material is usually adjusted to 0.005 to 2 g atoms/el, preferably 0.05 to 0.5 g atoms/' in total of yttrium and heavy rare earth,
The content of EDDA is adjusted to 0.3 to 2 times the mole, preferably 0.5 to 1 times the mole, relative to the content of yttrium and heavy rare earth. The method of the present invention lowers the pH of the extracted material to 6.5.
-9, preferably 7.5-8.5.

During the extraction operation, as rare earth ions are extracted into the extraction solvent, the pH of the aqueous solution decreases. , it is preferable to adjust the pH to the above range. Examples of the carboxylic acid extraction solvent used in the method of the present invention include naphthenic acids such as naphthenic acid 18, henaphthenic acid 230, and versatile acid 91
1, tertiary fatty acids typified by versatile acids such as versatile acid 10, and higher fatty acids such as isocaprylic acid.

Since these extraction solvents have high viscosity, it is desirable to dilute them with an organic diluent before use in order to reduce the viscosity and facilitate the extraction process. Organic diluents are usually
Aliphatic hydrocarbons such as kerosene and hexane, ethers such as dibutyl ether and diisopropyl ether, n-
Alcohol such as hexanol, benzene, xylene,
Aromatic hydrocarbons such as toluene are used. When using an organic diluent, the concentration of the extraction solvent should be 0.1~
It is preferable for the extraction operation to select the amount to be used so that it is about 2.5 mol/f, particularly about 0.5 to 1.5 mol/f.
In the method of the present invention, extraction is achieved by simultaneously establishing a complex formation equilibrium between rare earth ions and EDDA in the aqueous solution phase and an extraction equilibrium between rare earth ions in the extraction solvent and free rare earth ions in the aqueous solution phase. Since the solvent is enriched with yttrium, the extraction operation must be performed under conditions that achieve the above two equilibrium conditions, and the extraction time is as follows:
Usually, about 10 to 1 powder is sufficient.

The yttrium extracted and separated in the extraction solvent can be separated by ordinary back extraction using a mineral acid such as dilute hydrochloric acid, dilute nitric acid, dilute sulfuric acid, or the like.

As detailed above, if yttrium is extracted according to the method of the present invention, highly pure yttrium can be obtained very easily, so its industrial utility value is high. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist of the present invention is exceeded.

Example 1 Yttrium trichloride 0.05 mol/f, erbium trichloride 0.05 mol/f and EDDAO. OO8mol/'
An aqueous solution containing PH9. 50ml of the extracted material adjusted to O
Kerosene solution containing 1 mol/f (manufactured by Shell Chemical) 50
mL and was shaken for 1 min to perform extraction.

As a result, the extraction rate of yttrium was 88.5%, the extraction rate of erbium was 39.1%, and the separation coefficient between yttrium and erbium was 12. In addition, as a result of conducting the same experiment as above using dysprosium trichloride, holmium trichloride, and ytterbium trichloride instead of erbium trichloride, the separation coefficient between yttrium and dysprosium, holmium, and ytterbium was 3.9, respectively. 7.2 and 50 were heated. Example 2 Yttrium trichloride 0.05 mol/f and EDDAO
．． 50 ml of the extract obtained by adjusting the pH of an aqueous solution containing 8 mol/e of OO to 8.7 with aqueous ammonia, containing 1 mol/' of Versatake 10 (manufactured by Shell Chemical) and 0.05 g ion/' of erbium. The mixture was mixed with a keroses solution and shaken once to perform extraction.

As a result, 58.7% of the erbium contained in the keroses solution was transferred to the aqueous solution side, and 88.9% of the yttrium in the extract was extracted into the organic liquid phase. The separation coefficient between yttrium and erbium calculated from this example is 11
．． 4, which was approximately the same value as that obtained in Example 1. Example 3 Mixed rare earth oxide obtained from Malaysian xenotime (Y2O3 purity 60%, impurity content is shown in Table 1).

) in hydrochloric acid using di(2-ethylhexyl) phosphoric acid as an extraction solvent, intermediate feed type countercurrent extraction with three stages of extraction and three stages of washing was performed to remove light rare earths, and to remove yttrium and heavy The extraction solvent containing rare earth was brought into contact with a 5% by weight sulfuric acid aqueous solution to produce crude yttrium sulfate (the content of impurity rare earth was converted to oxide and shown in Table 1).
I got it. When the entire amount of the obtained crude yttrium sulfate was extracted with a kerosene solution containing 1 mol/' of Versatake 10 (manufactured by Shell Chemical), it was found to contain a total of 0.12 mol/' of yttrium and other rare earths. .

Claims (1)

[Claims] 1. It is characterized by selectively extracting yttrium by contacting an aqueous solution containing ethylenediamine-N,N'-diacetic acid, yttrium, and at least one kind of rare earth with an atomic number of 66 to 71 with a carboxylic acid extraction solvent. A method for separating yttrium.