JPH04147929A - Separation of rare earth element - Google Patents

Abstract

PURPOSE:To separate and recover rare earth elements in an organic solvent phase and an aqueous phase with superior separability by supplying a solution containing various rare earth elements into a pulse column containing an emulsion of organic solvent phase and aqueous phase. CONSTITUTION:An aqueous extract, such as dilute hydrochloric acid, is supplied from the top 11 of a pulse column 10 and an organic solvent is supplied from the bottom 12 of the column, and vibrations are applied to the whole solution to hold the inside of the column in an emulsive state. At this time, plural rare earth elements are incorporated into either of the aqueous extract or the organic solvent or an aqueous solution containing rare earth elements is supplied through the central part of the column 10 into the column to bring these rare earth elements into contact with the emulsion. The rare earth elements supplied into the column are efficiently separated into light rare earth elements and heavy rare earth elements and recovered in the aqueous extract phase and the organic solvent, respectively. Further, the aqueous extract and the organic solvent can be supplied into the column by providing mixer settlers 21, 22, and 23 to the top and bottom of the pulse column 10, respectively, and previously bringing the aqueous extract and the organic solvent into contact with each other via the above settlers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for separating rare earth elements that uses a pulse column and has a high separation effect.

Rare earth elements are widely used in magnetic materials, phosphors, electronic materials, optical materials, etc., and their applications are expanding further. The present invention relates to various rare earth elements.

In particular, it relates to a method for effectively separating and recovering heavy rare earths.

[Conventional technology and its issues]

As raw material ores for rare earth elements, monazite and bastnaesite are generally known as those with a high content of light rare earth, and porphyrite is known as an ore with a high content of heavy rare earth. By the way, when separating and recovering rare earth elements from such raw material ores, there are many types of rare earth elements mixed in the ore, and the properties of each element are similar, so it is difficult to separate and recover rare earth elements from other raw material ores. It is not easy to separate and recover.

Conventionally, as a method for separating and recovering rare earth elements.

An ion exchange method and a liquid-liquid solvent extraction method using a mixer settler are known.

In the above ion exchange method, a cation exchange resin and an anion exchange resin are appropriately used to sequentially adsorb and separate the target rare earth element. According to the ion exchange method, rare earth elements with relatively high purity can be obtained, but the rare earth elements that can be separated are limited depending on the type of ion exchange resin, and it is not suitable for separating a large number of rare earth elements. There is also a limit to the durability of the replacement resin, which poses a problem of high costs. Also, the throughput of the ion exchange method is limited.

It can be applied to small-scale processing, but is not suitable for industrial production.

On the other hand, the liquid-liquid solvent extraction method using a conventional mixer-settler has the advantage of lower production costs because it can process a larger amount of solution than the ion exchange method, and therefore the liquid-liquid solvent extraction method has traditionally been mainly practiced industrially. .

However, the conventional extraction method using a mixer-settler has the drawbacks of long processing time and a large amount of extraction solution.

Furthermore, the purity of the rare earth elements separated is lower than that obtained by the ion exchange method, and there is a problem in that the purification process becomes burdensome when used as a raw material in the field of electronic materials, for which demand has been increasing in recent years.

An object of the present invention is to provide a method for separating rare earth elements, which uses a pulse column instead of the conventional ion exchange method or method using a mixer settler, thereby greatly improving the separation effect.

[Structure and operation of the invention: means for solving problems] According to the present invention, an organic solvent phase and an aqueous phase are supplied into the column from the top and bottom of a pulsed column, respectively, and brought into countercurrent contact under pulsed vibration. Provided is a method for separating rare earth elements, which is characterized in that the rare earth elements dissolved in one of an organic solvent phase or an aqueous phase are extracted into the other.

Furthermore, according to the present invention, an organic solvent phase and an aqueous phase are supplied into the column from the top and bottom of the pulse column, respectively, and emulsified by countercurrent contact under pulse vibration, while rare earth elements are fed from the center of the column. A full phase method for extracting rare earth elements is provided, which is characterized in that a solution is fed into a column, and the rare earth elements are separated into an organic solvent phase and an aqueous phase for extraction.

Further, according to the present invention, in the above method for separating rare earth elements, a mixer settler is provided at the top and bottom of the pulse column, and after the organic phase and the aqueous phase are brought into contact with each other in advance through the mixer settler, the organic phase and the water phase are brought into contact with each other in the column. A separation method is provided, characterized in that:

In the separation method of the present invention, a pulse column is used. Although pulsed columns have been used in other fields, their use in separating rare earth elements is unknown. The general structure of a pulse column is that a large number of perforated plates are arranged at regular intervals along the axial direction within the column, and extractive liquid such as water and extracted elements are dissolved from the top and bottom of the column. and countercurrent contact with each other. At this time, by applying vertical pulse-like vibration (pulsation) to the liquid in the tower, the solution and extract liquid alternately form fine particles and mix and contact through the perforated plate, so the contact area increases significantly and a high extraction effect is achieved. Obtainable.

The separation method of the present invention can be applied to either the case where a rare earth element dissolved in an organic phase is extracted into an aqueous phase, or the case where a rare earth element dissolved in an aqueous phase is extracted into an organic phase. Hereinafter, a case will be described in which rare earth elements are separated and extracted from a rare earth element solution into an organic phase and an aqueous phase, respectively.

A weakly acidic aqueous solution such as dilute hydrochloric acid is supplied from the top of the pulse column as an extractant, and an organic solvent is supplied from the bottom of the column to vibrate the entire liquid to maintain an emulsion inside the column. On the other hand, an aqueous solution containing dissolved rare earth elements is supplied into the tower from the center of the tower. The aqueous solution of rare earth elements comes into contact with an organic solvent and a dilute aqueous hydrochloric acid solution in the tower, and depending on the pH of the solution, the rare earth elements are extracted into the organic phase according to their solubility, and other rare earth elements are extracted into the aqueous phase. This extraction separates the rare earth elements into two groups: an organic phase and an aqueous phase. The organic solvent is taken out of the system from the top of the pulse column, and after adjusting the PO by adding ammonia or the like as necessary, it is circulated back to the pulse column. After the extraction operation, the organic solvent and dilute aqueous hydrochloric acid solution are led out of the system, and if necessary, the rare earth elements dissolved in the organic solvent and dilute aqueous hydrochloric acid solution are further separated.
I is extracted. Note that when the separation and extraction are repeated by the method of the present invention, the type of rare earth element to be separated can be adjusted by adjusting the pH of the organic phase or the aqueous phase.

The separation method of the present invention includes an embodiment in which a mixer-settler is provided at the top and bottom of a pulse column, and the organic phase and aqueous phase are brought into contact through the mixer-settler and then supplied into the column. In extraction using a pulse column, in order to perform separation and extraction efficiently, it is necessary to maintain a high hold-up inside the column (high proportion of aqueous phase in the emulsion). As the rare earth elements move into the water phase within the tower, the specific gravity of the water phase gradually increases, making it easier for the water phase to fall, so strong pulsations are applied to the tower to maintain a high hold-up state. In this case, the specific gravity of the aqueous phase is low at the top of the tower where a new aqueous phase is supplied, and the specific gravity of the aqueous phase is low at the bottom of the tower where a new organic solvent is supplied as the rare earth elements are transferred from the aqueous phase to the organic phase. small. In this way, the specific gravity of the aqueous phase within the tower is not uniform. If the difference in specific gravity of the aqueous phase within the tower is large, it becomes difficult to maintain the inside of the tower in a highly bold-up state. Therefore, if a mixer-settler is provided at the top and bottom of the pulse column, and the organic solvent and dilute aqueous hydrochloric acid are brought into countercurrent contact through the mixer-settlers and then supplied into the column, the rare earth The organic solvent solution in which the elements are dissolved comes into contact with the newly supplied diluted hydrochloric acid aqueous solution, and a portion of the rare earth element is extracted into the diluted hydrochloric acid aqueous solution, thereby maintaining a high specific gravity of the aqueous phase supplied into the column. On the other hand, in the mixer settler at the bottom of the tower, the newly supplied organic solvent and dilute aqueous hydrochloric acid solution come into contact and a part of the rare earth elements dissolved in the dilute aqueous hydrochloric acid solution is extracted into the organic phase. When the aqueous phase comes into contact with the aqueous phase, there is little transfer of rare earth elements from the aqueous phase to the organic phase, and the specific gravity of the aqueous phase can be maintained high. Therefore, the inside of the column can be maintained in a high hold-up state, and the extraction and separation effect can be improved.

[Examples and comparative examples]

As shown in the figure, a pulse column (
Using a 15 cm ψ and a retained aqueous phase volume of 1321), a dilute aqueous hydrochloric acid solution was poured from the top of the column through a 1M mixer settler 22.23.
．． 2171/win is supplied, and an organic solvent (50%
-2-ethylhexyl phosphate ester, trade name PC-8
8A) at a rate of 3.36 1/min, the rare earth element-containing aqueous solution shown in the following table is fed into the column from the center of the column, and the organic solvent extracted from the top of the column is led to mixer settler 21.22. was brought into contact with a dilute aqueous hydrochloric acid solution supplied to

The composition of the pregnants extracted into the dilute aqueous hydrochloric acid solution is also shown in the following table.

Rare earth element Pr Nd Sm E
u, Gd7/-de composition 0.004 0
．． 148 0.934 0.166 0.
749 (mol/1) Preg composition 0.00
0 0.007 0.706 0.127 0
．． 572 (Iool/l) On the other hand, using a mixer settler (1101, 10 stages, amount of retained aqueous phase 275 R), the above diluted hydrochloric acid aqueous solution was added at a rate of 0.1411/sin.

While supplying the organic solvent at 2.191/win each, supplying the rare earth element aqueous solution from the center of the mixer settler,
Rare earth elements were separated and extracted. The composition of this pregnant is shown in the table below.

Rare earth element Pr Nd Sm E
u Gd preg composition 0.000 0.00
6 0.703 0.129 0.580
(mol/1) As is clear from the above results, according to the extraction method using the pulse column of the present invention, when achieving the same extraction effect as the method using the conventional mixer settler, There is an advantage that the amount of retained water phase is only about 172 times the amount of retained water phase in the mixer settler.

[Brief explanation of drawings]

The figure is a schematic diagram showing an embodiment of the method of the invention. In the drawing 10...Column, 11...Tower top, 12...
・Bottom, 21.22.23...Mixer settler patent applicant Mitsubishi Metals Corporation representative Patent attorney Masahiro Matsui (1 other person)

Claims (3)

[Claims] (1) An organic solvent phase and an aqueous phase are supplied into the column from the top and bottom of the pulse column, and are brought into countercurrent contact under pulse vibration to form an emulsion, and the organic solvent phase and the aqueous phase are dissolved in either the organic solvent phase or the aqueous phase. A method for separating rare earth elements characterized by extracting one rare earth element from another. (2) The organic solvent phase and the aqueous phase are supplied into the column from the top and bottom of the pulse column, respectively, and brought into countercurrent contact under pulse vibration to form an emulsion, while the rare earth element solution is fed into the column from the center of the column. A method for separating rare earth elements, characterized in that the rare earth elements are separated into an organic solvent phase and an aqueous phase and extracted. (3) A mixer-settler is provided at the top and bottom of the pulse column, and the organic phase and aqueous phase are brought into contact with each other through the mixer-settler before being supplied into the column. Claimed method for separating rare earth elements.