KR101459734B1 - Method of separating cerium from rare earth compounds - Google Patents

Abstract

The present invention relates to a method of separating Ce from a rare earth compound, specifically, a method of preparing a compound containing La and Ce; Selectively oxidizing Ce in the compound comprising La and Ce; And separating the Ce by leaching the compound containing the oxidized Ce to provide a method for separating Ce from the rare earth compound.

Description

[Technical Field] The present invention relates to a method for separating cerium from rare earth compounds,

And separating the Ce from the rare earth compound.

Rare earths are indispensable elements used in various high-tech industries such as LED, semiconductor, wind power, and green technology. Ce, which is used as abrasive and catalyst, is the most used element among 17 rare earths. It also has the highest content in the crust and the largest content in the center ore of the light rare earth.

And rare earth compounds such as oxides, chlorides, and carbonates are produced from the ores containing rare earths through eneloop, decomposition, leaching, etc., and the individual rare earth elements are separated therefrom. In the conventional separation method, the solvent extraction of an aqueous solution in which a rare earth compound is dissolved in an acid is performed. In the solvent extraction step of separating La and Ce, not only the separation factor of La and Ce is low, but also a large amount of Ce needs to be separated. There are many drawbacks to this.

It is possible to provide a method of isolating Ce more efficiently by using a method in which Ce, which occupies the largest amount of rare earth compounds, is not solvent extraction.

In one embodiment of the present invention, there is provided a method comprising: preparing a compound comprising La and Ce; Selectively oxidizing Ce in the compound comprising La and Ce; And separating Ce by leaching the compound containing oxidized Ce to provide a method for separating Ce from a rare earth compound.

Preparing the compound containing La and Ce may include preparing a compound including La and Ce, which comprises a light rare earth compound and a heavy rare earth compound.

Further, there is provided a process for preparing a compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, followed by acid treatment of the compound comprising La and Ce, including the light rare earth compound and the heavy rare earth compound And separating the light rare earth compound and the heavy rare earth compound from each other.

Further, there is also provided a process for separating the light rare earth compound from the heavy rare earth compound through an acid treatment of a compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, And separating the compound containing La and Ce from the light rare earth compound.

The step of separating the light rare earth compound and the heavy rare earth compound through an acid treatment of the compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, may be a step of solvent extraction.

Separating the compound containing La and Ce from the light rare earth compound through an acid treatment of the light rare earth compound may be a step of solvent extraction.

The step of selectively oxidizing Ce in the compound containing La and Ce may be a step in which the oxidation number of Ce is changed from +3 to +4.

In the step of selectively oxidizing Ce in the compound containing La and Ce, the oxidation temperature may be 500 to 700 ° C.

In the step of selectively oxidizing Ce in the compound containing La and Ce, the oxidation time may be 1 to 2 hours.

And leaching the compound containing oxidized Ce to separate Ce, the leaching may be leaching using an acid.

The concentration of the acid may be 2 to 3 normal concentrations.

And separating Ce by leaching the compound containing oxidized Ce, the leaching temperature may be 40 to 70 ° C.

In the step of separating Ce by leaching the compound containing oxidized Ce, the concentration of light at the initial leaching can be 100 to 300 g / L.

And separating Ce by leaching the compound containing oxidized Ce, the leaching may be repeated three to four times.

According to one embodiment of the present invention, Ce can be separated economically and at high efficiency by performing an oxidation and leaching process rather than a solvent extraction process.

It is possible to extract Ce from the rare earth compound with a high efficiency even if the equipment cost is more specifically reduced.

1 is a flow chart showing a method for separating Ce from a rare earth compound using a solvent extraction step.
FIG. 2 shows leaching rates of rare earth elements by oxidation and acid leaching experiments of La, Pr, Nd, and Sm rare earth carbonates having an oxidation number of Ce of +4 and an oxidation number of +3.
3 is a flow chart according to one embodiment of the present invention, which is a flow chart showing a method for separating Ce from a rare earth compound comprising an oxidation and leaching step.
4 is a flow diagram according to one embodiment of the present invention, which is a flow chart showing a method for separating Ce from a rare earth compound comprising an oxidation and leaching step.

Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.

One embodiment of the present invention is a method of preparing a compound comprising: preparing a compound comprising La and Ce; Selectively oxidizing Ce in the compound comprising La and Ce; And separating Ce by leaching the compound containing oxidized Ce to provide a method for separating Ce from a rare earth compound.

Rare earth elements are generic names of 17 elements combined with scandium and yttrium, the 3A group of the periodic table, and the lanthanide series of 15 elements with atomic numbers of 57 to 71, and have similar chemical properties and generally have an oxidation number of +3 . Rare earth elements are divided into ordinary rare earth elements and heavy rare earth elements. In this specification, the four elements from lanthanum (La) to atomic number 60 (Nd), which are atomic number 57, belong to light rare earth, Shall belong to the middle rare earth.

Hereinafter, the step of preparing a compound containing La and Ce will be described.

The step of preparing the compound containing La and Ce may be a step (S1) of preparing a compound containing La and Ce, which comprises a light rare earth compound and a heavy rare earth compound.

Specifically, the step of preparing a compound containing La and Ce,

After the step (S1) of preparing a compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, an acid treatment of the compound comprising La and Ce, comprising the light rare earth compound and the heavy rare earth compound (S2) separating the light rare earth compound and the heavy rare earth compound from each other,

 The step (S2) of separating the light rare earth compound and the heavy rare earth compound through acid treatment of the compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, Separating the light rare earth compound and the heavy rare earth compound by preparing a rare earth compound such as an oxide, chloride or carbonic acid by a method such as decomposition or leaching, and dissolving the rare earth compound in an acid.

More specifically, the step of preparing the compound containing La and Ce,

After the step (S2) of separating the light rare earth compound from the heavy rare earth compound through acid treatment of the compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, the acid treatment of the light rare earth compound (S3) separating the compound containing La and Ce from the light rare earth compound,

The step (S3) of separating the compound containing La and Ce from the light rare earth compound through the acid treatment of the light rare earth compound includes the step of irradiating the light rare earth compound (La, Ce, Pr, and Nd Is dissolved in an acid to obtain a compound containing La and Ce.

Meanwhile, the step (S2) of separating the light rare earth compound and the heavy rare earth compound through the acid treatment of the compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound, .

The step (S3) of separating the compound containing La and Ce from the light rare earth compound through the acid treatment of the light rare earth compound may be a step of solvent extraction.

Hereinafter, step (S4) of selectively oxidizing Ce in a compound containing La and Ce will be described.

Specifically, the step (S4) of selectively oxidizing Ce in the compound containing La and Ce may be a step in which the oxidation number of Ce changes from +3 to +4.

The Ce obtained in the natural state has an oxidation number of +3 as in other rare earth elements, but it can have an oxidation number of +4 through oxidation. Ce having an oxidation number of +3 and Ce having an oxidation number of +4 are different in properties, and Ce having an oxidation number of +3 is easily dissolved by an acid, whereas Ce having an oxidation number of +4 is changed to an acid So that the dissolution due to the reaction does not occur.

Ce has a property of being easily oxidized as compared with La and other rare earth elements. Therefore, when the temperature and the oxidation time during oxidation are appropriately controlled, only Ce can be oxidized (oxidation from Ce having +3 oxidation number to Ce having oxidation number of +4).

Specifically, in the step (S4) of selectively oxidizing Ce in the compound containing La and Ce, the oxidation temperature may be 500 to 700 ° C. More specifically, the oxidation temperature may be 550 to 650 ° C. If the oxidation temperature is within the above range, only Ce excluding La can be oxidized.

Specifically, in the step (S4) of selectively oxidizing Ce in the compound containing La and Ce, the oxidation time may be 1 to 2 hours. More specifically from 70 minutes to 100 minutes. When the time for the oxidation is within the above range, only Ce excluding La can be oxidized.

The step of selectively oxidizing Ce in the compound containing La and Ce (Step S4) is a method of separating Ce from the rare earth compound, which is different from the conventional separation method such as solvent extraction.

In general, it is difficult to separate La and Ce since the separation factor of La and Ce is low. For this reason, when the conventional solvent extraction method is used, the solvent extraction equipment becomes complicated and a large amount of expensive extraction agent used for solvent extraction is used There is a problem in that the separation efficiency of Ce is high because of the high cost of separation of Ce and the low separation factor of La and Ce.

However, since the method of separating Ce from the rare earth compound including selectively oxidizing Ce in the compound containing La and Ce uses oxidation and leaching, a separate extraction agent is unnecessary, Since La and Ce having different characteristics are changed by changing them, La and Ce having a low separation coefficient can be separated more efficiently.

That is, the step of selectively oxidizing Ce in the compound containing La and Ce (step S4) has a beneficial effect in terms of efficiency and cost as compared with the conventional solvent extraction method .

Hereinafter, step (S5) of separating Ce by leaching a compound containing oxidized Ce will be described.

In this specification, leaching refers to a method in which a compound containing various elements is dissolved in an acid solution so that the element dissolved in the acid solution remains in a liquid state and the element not dissolved in the acid solution remains in a solid state, .

Therefore, Ce having an oxidized +4 oxidation number is not dissolved in an acid solution but remains in a solid state. La having an oxidation number of +3 is dissolved in an acid solution and remains in a liquid state, so that La and Ce can be separated.

Specifically, in step (S5) of leaching a compound containing oxidized Ce to separate Ce, the leaching may be leaching using an acid. More specifically, the concentration of the acid used in the leaching may be 2 to 3 normal concentrations.

The acid used for the leaching may be hydrochloric acid, but it is not always limited thereto, and any material can be used as long as it is provided with a pair of non-covalent electrons when a coordination bond is formed.

Specifically, in step S5), the leaching temperature may be 40 to 70 ° C. More specifically, the leaching temperature may be 50 to 60 ° C.

Specifically, the step (S5) of leaching the oxidized Ce-containing compound to separate Ce from the initial leaching may be performed at a concentration of 100 to 300 g / L. More specifically, the initial liquid concentration may be 150-250 g / L.

Specifically, in step (S5) of separating Ce by leaching the compound containing oxidized Ce, the leaching may be repeated three to four times. More specifically, the leaching may be repeated three times.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following examples are intended to illustrate the present invention, but the present invention is not limited thereto.

Example  : Rare earth Carbonate  Oxidation and Acid leaching

50 g of a carbonate of Ce, La, Pr, Nd and Sm having an oxidation number of +3 is oxidized at 600 ° C for 90 minutes to change the oxidation number of Ce from +3 to +4 and the remaining La, Pr, Nd, And the oxidation number of Sm was kept at +3.

Thereafter, leaching was carried out at a temperature of 50 to 60 DEG C with a hydrochloric acid having a concentration of 2.5 normal, and the concentration of the liquid at the initial leaching was adjusted to 200 g / L. After each leaching, only the solids were separated and the next leaching proceeded, and finally the separated solid was dried and calcined to obtain the oxide type compound. FIG. 2 shows the result of repeating this process up to five times under the above conditions.

2,

La and Ce can be ideally separated if the leaching rate of Ce is minimized and the leaching rate of La is maximized. According to Fig. 2, when the leaching is repeated up to three times, the leaching rate of Ce becomes 1% or less and the leaching rate of La becomes 95% or more. That is, it can be seen that the solid state Ce (+4 oxidation number) compound and the liquid state La (+3 oxidation number) compound are separated.

In addition, when the leaching is performed only once, the leaching rate of La is low, so that La may function as an impurity in the Ce compound and the purity of the separated Ce may be lowered. If the leaching is repeated 5 times or more , The leaching rate of Ce is increased and the amount of Ce to be separated may be decreased. As a result, the number of leaching times is preferably 3 to 4 times.

However, elements such as Pr, Nd, and Sm do not have a higher leaching rate than La, and may act as impurities in the Ce compound to lower the purity. Accordingly, the step of oxidizing Ce having an oxidation number of +3 to an oxidation number of +4 according to an embodiment of the present invention is carried out before the step of separating the light rare earth compound and the heavy rare earth compound by acid treatment of the rare earth compound It is possible to increase the purity and amount of Ce when it is carried out after the step of separating the compound containing La and Ce through the acid treatment of the light rare earth compound.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the invention.

Claims (14)

Preparing a compound comprising La and Ce;
Selectively oxidizing Ce in the compound comprising La and Ce; And
Separating Ce by leaching the compound containing oxidized Ce;
Lt; / RTI >
Preparing a compound containing La and Ce;
Preparing a compound comprising La and Ce, comprising a light rare earth compound and a heavy rare earth compound;
Separating the light rare earth compound and the heavy rare earth compound through an acid treatment of a compound comprising La and Ce, the light rare earth compound and the heavy rare earth compound; And
And separating the compound containing La and Ce from the light rare earth compound through an acid treatment of the light rare earth compound,
Separating the compound containing La and Ce from the light rare earth compound through an acid treatment of the light rare earth compound,
Wherein the step is carried out by a solvent extraction method. delete delete delete The method according to claim 1,
Separating the light rare earth compound and the heavy rare earth compound through an acid treatment of a compound containing La and Ce, which comprises the light rare earth compound and the heavy rare earth compound,
A method for separating Ce from a rare earth compound, which is a step of solvent extraction. delete The method according to claim 1,
Selectively oxidizing Ce in the compound comprising La and Ce,
Wherein the oxidation number of Ce is changed from +3 to +4. The method according to claim 1,
And selectively oxidizing Ce in the compound containing La and Ce, wherein the temperature for the oxidation is 500 to 700 占 폚. The method according to claim 1,
And selectively oxidizing Ce in the compound containing La and Ce, wherein the time of oxidation is 1 to 2 hours. The method according to claim 1,
And separating the Ce by leaching the compound containing the oxidized Ce, wherein the leaching is carried out using an acid. 11. The method of claim 10,
Wherein the concentration of said acid is from 2 to 3 normal concentrations. The method according to claim 1,
And separating Ce by leaching the oxidized Ce-containing compound, wherein the leaching temperature is 40 to 70 占 폚. The method according to claim 1,
And separating Ce from the compound containing the oxidized Ce, wherein the concentration of Ce in the rare earth compound is 100 to 300 g / L at the initial leaching. delete

Images