阅读说明：本技术 超纯二氧化铈的制备方法 (Preparation method of ultrapure cerium dioxide ) 是由 刘荣丽 王志坚 王贵超 吴希桃 罗勉 石雪峰 罗芝雅 于 2021-08-12 设计创作，主要内容包括：本发明涉及一种超纯二氧化铈的制备方法中,将含有Pr元素的碳酸铈原料、酸溶液和氧化剂进行氧化反应,得到含铈的稀土溶液；然后将含铈的稀土溶液采用稀土萃取剂进行萃取,制得负载铈的有机相；再将负载铈的有机相采用反萃剂进行反萃,得到反萃液；进一步将反萃液采用萃淋树脂色层法进行分离提纯,得到淋出液；再将淋出液与氨水进行沉淀反应,得到沉淀物；最后将沉淀物溶于酸液中,加入草酸进行沉淀,煅烧,得到二氧化铈。该制备方法能得到纯度在99.9999％及以上的超高纯CeO-(2)产品,收率高,制备条件温和,适宜工业化生产。(The invention relates to a preparation method of ultrapure cerium dioxide, which comprises the steps of carrying out oxidation reaction on a cerium carbonate raw material containing Pr element, an acid solution and an oxidant to obtain a cerium-containing rare earth solution; then extracting the rare earth solution containing cerium by using a rare earth extractant to prepare a cerium-loaded organic phase; then carrying out back extraction on the cerium-loaded organic phase by using a back extractant to obtain a back extraction solution; further separating and purifying the stripping solution by a chromatography of extraction resin to obtain a leaching solution; then carrying out precipitation reaction on the leachate and ammonia water to obtain a precipitate; and finally dissolving the precipitate in acid liquor, adding oxalic acid for precipitation, and calcining to obtain the cerium dioxide. The preparation method can obtain ultra-pure CeO with the purity of 99.9999 percent or above 2 The product has high yield and mild preparation conditions, and is suitable for industrial production.)

1. A method for preparing ultrapure ceria, comprising the steps of:

carrying out oxidation reaction on a cerium carbonate raw material, an acid solution and an oxidant to obtain a cerium-containing rare earth solution; the cerium carbonate raw material contains Pr element;

extracting the cerium-containing rare earth solution by using a rare earth extractant to prepare a cerium-loaded organic phase;

carrying out back extraction on the cerium-loaded organic phase by adopting a back extractant to obtain a back extraction solution; the stripping agent is ascorbic acid aqueous solution;

purifying the back extraction solution by adopting an extraction resin chromatography to obtain a leaching solution;

carrying out precipitation reaction on the leachate and ammonia water to obtain a precipitate;

and dissolving the precipitate in acid liquor, adding oxalic acid for precipitation, and calcining to obtain the ultrapure cerium dioxide.

2. The process for the preparation of ultrapure ceria according to claim 1 wherein the step of purifying the strip liquor by chromatography on a lixiviant resin comprises the steps of:

loading the stripping solution into a extraction resin separation column, and then leaching with water to form a cerium-containing rare earth adsorption column;

connecting the cerium-containing rare earth adsorption column with N extraction resin separation columns in series, then leaching by adopting an acid leacheate, and receiving a leachate of which the percentage of the mass of cerium to the total mass of rare earth elements is greater than or equal to 6N;

wherein the acidity of the acid leacheate is 0.03-0.1 mol/L; n is an integer greater than or equal to 1.

3. The process for the preparation of ultrapure ceria according to claim 2, wherein the acid in the acid rinse is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid or acetic acid; and/or

The leaching speed of the acid leaching solution is 0.3 cm/min-0.7 cm/min.

4. The method of preparing ultrapure ceria according to claim 2, wherein in the step of loading the strip liquor in a extraction resin separation column, the strip liquor has an adsorption rate of 0.1cm/min to 0.5 cm/min; and/or

The ratio of the diameter to the height of the extraction resin separation column is 1 (10-30).

5. The method of preparing ultrapure ceria according to any one of claims 1 to 4, wherein the molar weight ratio of acid in the acid solution to the cerium carbonate starting material is (1.2-1.5): 1; and/or

The acid in the acid solution is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid.

6. The method of preparing ultrapure ceria of claim 5, wherein the molar weight ratio of the oxidant to the cerium carbonate feedstock is (1-5): 1; and/or

The oxidant is selected from potassium bromate, potassium permanganate and H₂O₂At least one of (1).

7. The method of any of claims 1 to 4 and 6, wherein the rare earth extractant comprises an organic extractant selected from at least one of tributyl phosphate, diisooctyl phosphate and diisooctyl isooctyl phosphate, and a diluent selected from at least one of liquid paraffin and kerosene; and/or

The volume ratio of the organic extractant to the diluent is (10-60) to (40-90).

8. The process for the preparation of ultrapure cerium dioxide according to any one of claims 1 to 4 and 6,

in the extraction step, the extraction ratio O/A is (1-3): 1; and/or

In the back extraction step, the back extraction ratio O/A is (1-3): 1.

9. The process for the preparation of ultrapure cerium dioxide according to any one of claims 1 to 4 and 6,

the acidity of the rare earth solution containing cerium is 5.0-10.0 mol/L; and/or

The concentration of cerium in the cerium-containing rare earth solution is 0.1-0.3 mol/L.

10. The method for producing ultrapure ceria according to any one of claims 1 to 4 and 6, wherein the acid solution is at least one selected from the group consisting of hydrochloric acid, nitric acid and sulfuric acid; and/or

The alkalinity of the ammonia water is 1.0 mol/L-5.0 mol/L.

Technical Field

The invention relates to the technical field of rare earth, in particular to a preparation method of ultrapure cerium dioxide.

Background

The ultra-pure rare earth product can be made into new materials with multiple functions and is widely applied to the preparation of industrial products and the advanced field of national defense. Wherein, ceria (CeO)₂) The rare earth is an important rare earth product, and due to the special property, the rare earth can be used for preparing industrial products such as luminescent materials, catalysts, glass, ceramics and the like, and can also be applied to a plurality of advanced fields such as electronics, laser, nuclear industry, superconduction and the like. CeO (CeO)₂The purity of the product determines the performance of the material, and the CeO is treated along with the development of science and technology and the improvement of the production level₂The purity of the product puts higher demands.

CeO₂The purity of the product refers to the CeO in the product₂The ratio of the mass of CeO to the total mass of the rare earth oxides in the product is recorded as CeO₂The purity of the/TREO (total mass of rare earth oxides) can be divided into: low-purity products with the purity not higher than 99 percent, high-purity products with the purity of 99.9 to 99.99 percent and ultra-high-purity products with the purity of 99.999 percent or above. At present, extraction method is mostly adopted to produce CeO in industry₂Obtained CeO₂The purity of the product is generally 99-99.9%, and the main reasons are that Ce and Pr are adjacent rare earth elements, the separation coefficient is extremely small, and CeO₂Rare earth impurities such as Pr and the like and other non-rare earth impurities cannot be deeply removed. Some technologies adopt acid to oxidize trivalent cerium into quadrivalent cerium, and then extract and purify the tetravalent cerium to prepare CeO₂But which is purified to give CeO₂The purity of the product is not higher than 99.99 percent, and ultra-pure CeO is difficult to obtain₂And (5) producing the product. The skilled artisan has tried to prepare ultra-pure CeO by a pressurized ion exchange process₂However, the preparation conditions of the pressurized ion exchange method are harsh, and industrial production is difficult to carry out.

Thus, the prior art remains to be improved.

Disclosure of Invention

Based on the method, the invention provides a preparation method of ultrapure cerium dioxide, which is beneficial to improving CeO₂The product has high purity and yield, mild preparation conditions and suitability for industrial production.

The technical scheme of the invention is as follows.

In one aspect of the present invention, there is provided a method for preparing ultrapure ceria, comprising the steps of:

carrying out oxidation reaction on a cerium carbonate raw material, an acid solution and an oxidant to obtain a cerium-containing rare earth solution; the cerium carbonate raw material contains Pr element;

extracting the cerium-containing rare earth solution by using a rare earth extractant to prepare a cerium-loaded organic phase;

carrying out back extraction on the cerium-loaded organic phase by adopting a back extractant to obtain a back extraction solution; the stripping agent is ascorbic acid aqueous solution;

separating and purifying the back extraction solution by adopting an extraction resin chromatography to obtain a leaching solution;

carrying out precipitation reaction on the leachate and ammonia water to obtain a precipitate;

and dissolving the precipitate in acid liquor, adding oxalic acid for precipitation, and calcining to obtain the ultrapure cerium dioxide.

In some embodiments, the step of separating and purifying the stripping solution by chromatography using extraction resin comprises the following steps:

loading the stripping solution into a extraction resin separation column, and then leaching with water to form a cerium-containing rare earth adsorption column;

connecting the cerium-containing rare earth adsorption column with N extraction resin separation columns in series, then leaching by adopting an acid leacheate, and receiving a leachate of which the percentage of the mass of cerium to the total mass of rare earth elements is greater than or equal to 6N;

wherein the acidity of the acid leacheate is 0.03-0.1 mol/L; n is an integer greater than or equal to 1.

In some of these embodiments, the acid in the acid rinse is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, or acetic acid; and/or

The leaching speed of the acid leaching solution is 0.3 cm/min-0.7 cm/min.

In some embodiments, in the step of loading the stripping solution into the extraction resin separation column, the adsorption speed of the stripping solution is 0.1cm/min to 0.5 cm/min; and/or

The ratio of the diameter to the height of the extraction resin separation column is 1 (10-30).

In some of these embodiments, the molar ratio of acid in the acid solution to the cerium carbonate starting material is (1.2-1.5): 1; and/or

The acid in the acid solution is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid.

In some of these embodiments, the molar ratio of the oxidizing agent to the cerium carbonate starting material is (1-5): 1; and/or

The oxidant is selected from potassium bromate, potassium permanganate and H₂O₂At least one of (1).

In some of these embodiments, the rare earth extractant includes an organic extractant selected from at least one of tributyl phosphate, diisooctyl phosphate, and diisooctyl isooctyl phosphate, and a diluent selected from at least one of liquid paraffin and kerosene; and/or

The volume ratio of the organic extractant to the diluent is (10-60) to (40-90).

In some of these embodiments, the step of extracting comprises extracting the mixture with an O/A ratio of (1-3): 1; and/or

In the back extraction step, the back extraction ratio O/A is (1-3): 1.

In some of the embodiments, the acidity of the cerium-containing rare earth solution is 5.0mol/L to 10.0 mol/L; and/or

The concentration of cerium in the cerium-containing rare earth solution is 0.1-0.3 mol/L.

In some of these embodiments, the acid solution is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid; and/or

The alkalinity of the ammonia water is 1.0 mol/L-5.0 mol/L.

In the preparation method of the ultrapure cerium dioxide, a cerium carbonate raw material containing Pr element, an acid solution and an oxidant are subjected to oxidation reaction to obtain a cerium-containing rare earth solution; wherein the oxidizing agent is trivalentCerium is oxidized to tetravalent cerium. Then extracting the rare earth solution containing cerium by using a rare earth extractant to prepare a cerium-loaded organic phase; the extractant can remove Ce in the cerium-loaded rare earth solution⁴⁺Ion extraction to remove Ce⁴⁺Most rare earth impurity ions except for the rare earth impurity ions. Then carrying out back extraction on the cerium-loaded organic phase by using a back extractant to obtain a back extraction solution; using reductive ascorbic acid water solution as a stripping agent, and further utilizing reduction reaction to strip out cerium in the loaded organic phase; further separating and purifying the stripping solution by a chromatography of extraction resin to obtain a leaching solution; precipitating the leachate with ammonia water to obtain precipitate cerium hydroxide, and further removing impurities dissolved in the ammonia water; finally dissolving the precipitate in acid liquor, adding oxalic acid for precipitation, further removing impurities dissolved in oxalic acid, and calcining to obtain ultra-pure cerium dioxide, wherein the ultra-pure CeO with the purity of 99.9999% or more can be obtained by the preparation method₂The product has mild preparation conditions and is suitable for industrial production.

Further, in the preparation method, in the step of purifying the back extraction solution by adopting a chromatography of the extraction resin, the back extraction solution is loaded in the separation column of the extraction resin, and then is leached by adopting water to form the cerium-containing rare earth adsorption column; then connecting a cerium-containing rare earth adsorption column and N extraction resin separation columns in series, then leaching by adopting an acid leacheate, and receiving a leachate of which the total mass percentage of rare earth elements is more than or equal to 6N; wherein the acidity of the acid leacheate is 0.03-0.1 mol/L; n is an integer greater than or equal to 1. Thus, ultra-pure CeO with a purity of 99.9999% or more can be obtained without the need of an expensive chelate eluent₂And (5) producing the product.

Further, the acid in the acid leaching solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid or acetic acid, so that the pollution to the environment caused by the use of high-acid leaching agents such as hydrofluoric acid, perchloric acid and the like can be avoided, and the cost is further reduced.

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

One embodiment of the present invention provides a method for preparing ultrapure ceria, comprising the following steps S10 to S60.

Step S10, carrying out oxidation reaction on a cerium carbonate raw material, an acid solution and an oxidant to obtain a cerium-containing rare earth solution; the cerium carbonate raw material contains Pr element.

And S20, extracting the cerium-containing rare earth solution obtained in the step S10 by using a rare earth extracting agent to obtain a cerium-loaded organic phase.

Step S30, performing back extraction on the cerium-loaded organic phase obtained in the step S20 by using a back extractant to obtain a back extraction solution; the stripping agent is ascorbic acid aqueous solution.

And S40, separating and purifying the back extraction solution obtained in the step S30 by using extraction resin chromatography to obtain a leaching solution.

And S50, carrying out precipitation reaction on the leachate obtained in the step S40 and ammonia water to obtain a precipitate.

And S60, dissolving the precipitate obtained in the step S50 in acid liquor, adding oxalic acid for precipitation, and calcining to obtain the ultrapure cerium dioxide.

In the preparation method of the ultrapure cerium dioxide, a cerium carbonate raw material containing Pr element, an acid solution and an oxidant are subjected to oxidation reaction to obtain a cerium-containing rare earth solution; wherein the oxidizing agent oxidizes trivalent cerium into tetravalent cerium. Then, extracting the rare earth solution containing cerium by using a rare earth extractant to obtain a cerium-loaded organic phase; extraction ofThe agent can remove Ce in cerium-containing rare earth solution⁴⁺The ions are extracted to remove most of the other rare earth impurities. Then carrying out back extraction on the cerium-loaded organic phase by using a back extractant to obtain a back extraction solution; a reductive ascorbic acid aqueous solution is used as a stripping agent, and cerium in the organic phase is further stripped through a reduction reaction; further purifying the back extraction solution by using a chromatography of extraction resin to obtain a leaching solution; precipitating the leachate with ammonia water to obtain precipitate cerium hydroxide, and further removing impurities dissolved in the ammonia water; finally dissolving the precipitate in acid liquor, adding oxalic acid for precipitation, and further removing impurities dissolved in oxalic acid; by calcining rare earth oxalate to obtain ultra-pure cerium dioxide, the preparation method can obtain ultra-pure CeO with the purity of 99.9999 percent or above₂The product has mild preparation conditions and is suitable for industrial production.

It is understood that the above-mentioned raw material for cerium carbonate contains not only the compound cerium carbonate but also a compound of the Pr element. Further, the above-mentioned cerium carbonate raw material may further contain other rare earth elements, for example, La element and/or Nd element and/or Sm element and/or Eu element and/or Gd element.

Further, the cerium carbonate raw material may further contain a non-rare earth element, for example, at least one of Fe element, Si element, Ca element, Mg element, Ni element, Cu element, Zn element, and Mn element.

In some embodiments, in step S10, the mass percentage of the total Rare Earths (REO) in the cerium carbonate raw material is 60% to 74%; furthermore, the mass proportion of the cerium carbonate in the cerium carbonate raw material in the total Rare Earth (REO) is 99-99.9%.

In some embodiments, the molar ratio of the acid in the acid solution to the cerium carbonate raw material is (1.2-1.5): 1.

Molar amount is the amount of material.

In some of these embodiments, the acid in the acid solution is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

Preferably, the acid in the acid solution is selected from nitric acid. Nitric acid has strong oxidizing property and can further cooperate with an oxidizing agent to oxidize trivalent cerium into tetravalent cerium.

In some embodiments, the molar ratio of the oxidant to the cerium carbonate raw material is (1-5): 1.

In some of these embodiments, the oxidizing agent is selected from the group consisting of potassium bromate, potassium permanganate, and H₂O₂At least one of (1).

In some embodiments, the acidity of the cerium-containing rare earth solution is 5.0mol/L to 10.0 mol/L.

In some embodiments, the concentration of cerium in the cerium-containing rare earth solution is 0.1mol/L to 0.3 mol/L.

In some embodiments, in step S20, the rare earth extractant includes an organic extractant and a diluent, the organic extractant is selected from at least one of tributyl phosphate, diisooctyl phosphate and diisooctyl isooctyl phosphate, and the diluent is selected from at least one of liquid paraffin and kerosene.

Specifically, the rare earth extractant is at least one selected from a mixed solution of tributyl phosphate and liquid paraffin, a mixed solution of tributyl phosphate and kerosene, a mixed solution of diisooctyl phosphate and kerosene, and a mixed solution of diisooctyl isooctyl phosphate and kerosene.

In some embodiments, the volume ratio of the organic extractant to the diluent is (10-60) to (40-90).

In some embodiments, in the step S20, the extraction phase ratio O/A in the step of extracting is (1-3): 1;

in some embodiments, in the step S30, the stripping ratio O/A in the stripping step is (1-3): 1.

In some embodiments, in step S40, the step of separating and purifying the stripping solution by chromatography with extraction resin includes steps S41 to S42.

And step S41, loading the strip liquor into the extraction resin separation column, and then leaching with water to form the cerium-containing rare earth adsorption column.

Step S42, connecting a cerium-containing rare earth adsorption column and N extraction resin separation columns in series, then leaching by adopting acid leacheate, and receiving leachate of which the percentage of the mass of cerium to the total mass of rare earth elements is greater than or equal to 6N;

wherein the acidity of the acid leacheate is 0.03-0.1 mol/L; n is an integer greater than or equal to 1.

Further, the acid in the acid leacheate is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid or acetic acid. Specifically, the acid in the acid leacheate is selected from hydrochloric acid. Therefore, the pollution of the use of the high-acid eluent such as hydrofluoric acid, perchloric acid and the like to the environment can be avoided, and the cost is further reduced. Ultra-high purity CeO with the purity of 99.9999 percent or more can be obtained without using a high-acid eluting agent and a high-price chelating eluting agent₂And (5) producing the product.

In some embodiments, in the step S41, in the step of rinsing with water, rinsing is stopped until the pH of the effluent of the formed cerium-containing rare earth adsorption column is 3-7. Therefore, the pH value of the liquid in the rare earth adsorption column can be adjusted, a proper pH value environment is provided for the subsequent leaching and purifying steps, and the purity of the obtained leaching liquid is further improved.

In some embodiments, in step S41, in the step of loading the stripping solution on the extraction resin separation column, the adsorption speed of the stripping solution is 0.1cm/min to 0.5 cm/min. Further, in the feeding step, the feeding is stopped until the rare earth element appears in the effluent of the extraction resin separation column.

In some embodiments, in step S41, before the step of loading the stripping solution into the extraction resin separation column, the method further includes diluting the stripping solution with water until the pH of the diluted stripping solution is 2 to 5 and the concentration of the rare earth element is 5.0g/L to 30.0 g/L.

In some of these embodiments, n is an integer from 2 to 5.

It can be understood that in step S42, the step of receiving the eluate is to receive the eluate of the last extraction resin separation column connected in series, and detect the components of the eluate on line.

In some embodiments, before the step of receiving the leachate containing cerium and the rare earth element with a percentage of the total mass of the rare earth element greater than or equal to 6N, in step S42, the method further includes the following steps:

and (4) receiving leachate with the rare earth element concentration lower than 0.05g/L, and treating sewage. Further, the air conditioner is provided with a fan,

and (3) receiving the leachate with the rare earth element concentration of more than 0.05g/L and the percentage of the mass of Ce to the total mass of the rare earth elements of less than 6N, recovering the leachate, and further performing the operations of the steps S41-S42 as a raw material for the next purification operation.

It should be noted that in the art, N represents "9" and 6N represents 99.9999% purity.

The leachate with the mass percentage of the cerium to the total mass of the rare earth elements being less than 6N represents that the mass percentage of the cerium in the leachate/the total mass of the rare earth elements in the leachate is less than 99.9999 percent and is marked as CeO₂/REO。

In some embodiments, the column diameter of the extraction resin separation column is: the column height is 1 (10-30), and the extraction resin separation column is a phosphorus-containing extraction resin separation column. The appropriate ratio of column diameter to column height is beneficial to improving the purification efficiency.

In some embodiments, in step S50, before the step of performing the precipitation reaction on the leachate obtained in step S40 and ammonia water, the method further includes a step of concentrating the leachate.

Further, the concentration step is carried out by heating and evaporating, and the concentration of the rare earth elements in the concentrated leachate is 5 g/L-20.0 g/L.

In some of the embodiments, the alkalinity of the ammonia water is 1.0mol/L to 5.0 mol/L.

In some of the embodiments, in step S60, the acid solution is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid. Further, the acidity of the acid solution is 1.0mol/L to 5.0 mol/L.

Further, the acid solution is an analytically pure acid solution and is obtained by 2-3 times of distillation and purification.

In some embodiments, the oxalic acid in the oxalic acid solution is analytically pure and is obtained by 2 to 3 times of recrystallization. Furthermore, the mass concentration of oxalic acid in the oxalic acid solution is 50 g/L-70 g/L.

In some of the examples, in step S60, the calcination conditions are: calcining for 3-5 h at 850-950 ℃.

While the present invention will be described with respect to particular embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover by the appended claims the scope of the invention, and that certain changes in the embodiments of the invention will be suggested to those skilled in the art and are intended to be covered by the appended claims.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Example 1

(1) Preparing feed liquid: providing a cerium carbonate raw material, wherein the total rare earth mass TREO accounts for 71 wt% of the cerium carbonate raw material, and CeO₂the/TREO content is 99%, the cerium carbonate raw material also contains other rare earth elements such as Pr and La and non-rare earth elements such as Fe, Si, Ca, Mg, Ni, Cu, Zn and Mn, and the nitric acid solution is added according to the molar ratio of 1.2:1 of the nitric acid to the cerium carbonate to be dissolved until the cerium carbonate is clear; adding an oxidant according to the mol ratio of the oxidant (potassium bromate) to the cerium carbonate of 1:1, and oxidizing trivalent cerium into tetravalent cerium to obtain a cerium-containing rare earth solution, wherein the concentration of cerium is 0.1mol/L, and the acidity is 5.0 mol/L.

(2) And (3) extraction: adding a cerium-containing rare earth solution into a single-stage extraction tank containing an extractant, wherein the extractant is a mixed solution composed of tributyl phosphate and liquid paraffin, and the volume ratio of the tributyl phosphate to the liquid paraffin is 10: and 90, stirring and extracting, wherein the extraction ratio O/A is 1:1, standing and layering after extraction is finished, and thus obtaining the cerium-loaded organic phase.

(3) Back extraction: preparing a stripping agent by adopting ascorbic acid and pure water according to the concentration of 0.1 wt%, adding the stripping agent into the cerium-loaded organic phase, wherein the stripping ratio O/A is 1:1, stirring and stripping, standing and layering after the stripping is finished, and discharging stripping solution.

(4) The chromatography purification of the levextrel resin comprises the following steps:

adsorption: diluting the stripping solution by pure water until the pH value of the stripping solution is 2, wherein the concentration of rare earth elements in the stripping solution is 5.0g/L, placing the stripping solution in an overhead tank, adsorbing the stripping solution by an extraction resin separation column, controlling the feeding flow rate of the stripping solution to be 0.1cm/min, monitoring the pH of the outlet solution of the extraction resin separation column and the change of the concentration of the rare earth elements in real time on line, and stopping feeding until the rare earth elements appear in the outlet solution of the exchange column. And then eluting the exchange column loaded with the stripping solution by pure water until the pH value of the outlet solution is 3, and stopping eluting to form the rare earth adsorption column. Wherein, the extraction resin separation column is a phosphorus-containing extraction resin separation column, and the column diameter is as follows: the column height is 1: 10.

leaching: connecting the rare earth adsorption column with a second extraction resin separation column in series, eluting with 0.03mol/L hydrochloric acid solution, controlling the elution speed to be 0.3cm/min, detecting the concentration of rare earth elements in the solution at the outlet of the second exchange column on line, when the rare earth elements appear in the solution at the outlet, connecting a third exchange column in series to continue eluting, detecting the concentration of all the rare earth elements and the purity of cerium relative to the rare earth elements in the solution at the outlet of the third exchange column on line, and when the concentration of the rare earth elements in the solution at the outlet is lower than 0.05g/L, directly feeding the effluent solution into a sewage treatment station for treatment; when the rare earth concentration of the outlet solution is more than 0.05g/L, the relative purity of cerium is less than 6N (CeO)₂When REO is less than 99.9999 percent), recovering leachate; when the relative purity of the rare earth in the outlet solution is more than or equal to 6N (CeO)₂REO is more than or equal to 99.9999 percent), and collecting leachate.

(5) And (3) precipitation: heating and concentrating the leaching solution until the concentration of the rare earth elements reaches 5g/L, precipitating the concentrated solution by using ammonia water with the excess of 1.0mol/L, then performing suction filtration to obtain cerium hydroxide precipitate, and washing the cerium hydroxide precipitate for multiple times by using pre-boiling ultrapure water.

(6) Preparation of cerium dioxide: preparing hydrochloric acid solution with acidity of 1.0mol/L by using hydrochloric acid subjected to distillation and purification for 2 times, and dissolving cerium hydroxide to obtain a dissolved solution. Then adding oxalic acid solution with the mass concentration of 50g/L of oxalic acid for precipitation, and performing suction filtration to obtain rare earth oxalate precipitate. Then placing the rare earth oxalate precipitate in a muffle furnace for drying, and calcining for 3h at the high temperature of 850 ℃ to obtain a cerium dioxide product. Wherein oxalic acid in the oxalic acid solution is recrystallized for 2 times.

(7) And (3) detection: the cerium dioxide product obtained above was analyzed and detected, and the product analysis results are shown in table 1. As a result, it was found that the purity of the cerium oxide product obtained as described above was 6N or more.

Wherein TREO represents the total mass of rare earth oxides in the resulting ceria product. The product yield was calculated as the ratio of the mass of cerium oxide actually obtained to the mass of cerium oxide theoretically to be obtained.

TABLE 1

Example 2

(1) Basically the same as example 1, step (1), except that: adding a nitric acid solution according to the molar ratio of the nitric acid to the cerium carbonate of 1.5:1, and dissolving until the mixture is clear; adding an oxidant according to the mol ratio of the oxidant (potassium bromate) to the cerium carbonate of 5:1, and oxidizing trivalent cerium into tetravalent cerium to obtain a cerium-containing rare earth solution, wherein the concentration of cerium is 0.3mol/L, and the acidity is 10.0 mol/L.

(2) Basically the same as example 1, step (2), except that: the organic phase consists of tributyl phosphate and liquid paraffin, and the volume ratio of the tributyl phosphate to the liquid paraffin is 60: 40, the extraction phase ratio O/A is 3: 1.

(3) Basically the same as example 1, step (3), except that: adding ascorbic acid into pure water according to the proportion of 0.5 wt% to prepare a stripping agent, and adding the stripping agent into the cerium-loaded organic phase, wherein the stripping ratio O/A is 3: 1.

(4) The chromatography purification of the levextrel resin comprises the following steps:

adsorption: diluting the stripping solution by pure water until the pH value of the stripping solution is 5, wherein the concentration of rare earth elements in the stripping solution is 30.0g/L, placing the stripping solution in an overhead tank, adsorbing the stripping solution by an extraction resin separation column, controlling the feeding flow rate of the stripping solution to be 0.5cm/min, monitoring the pH of the outlet solution of the extraction resin separation column and the change of the concentration of the rare earth elements in real time on line, and stopping feeding until the rare earth elements appear in the outlet solution of the exchange column. And then eluting the exchange column loaded with the stripping solution by pure water until the pH value of the outlet solution is 6, and stopping eluting to form the rare earth adsorption column. Wherein, the extraction resin separation column is a phosphorus-containing extraction resin separation column, and the column diameter is as follows: the column height is 1: 30.

leaching: connecting the rare earth adsorption column with a second extraction resin separation column in series, leaching with 0.1mol/L hydrochloric acid solution, controlling the leaching speed to be 0.7cm/min, detecting the concentration of rare earth elements in the solution at the outlet of the second exchange column on line, when the rare earth elements appear in the solution at the outlet, connecting a third exchange column in series to continue leaching, detecting the concentration of all the rare earth elements and the purity of cerium relative to the rare earth elements in the solution at the outlet of the third exchange column on line, and when the concentration of the rare earth elements in the solution at the outlet is lower than 0.05g/L, directly feeding the effluent solution into a sewage treatment station for treatment; when the rare earth concentration of the outlet solution is more than 0.05g/L, the relative purity of cerium is less than 6N (CeO)₂When REO is less than 99.9999 percent), recovering leachate; when the relative purity of the rare earth in the outlet solution is more than or equal to 6N (CeO)₂REO is more than or equal to 99.9999 percent), and collecting leachate.

(4) Precipitation and impurity removal: heating and concentrating the leaching solution until the concentration of the rare earth elements reaches 20g/L, precipitating the concentrated solution by using excessive 5.0mol/L ammonia water, then performing suction filtration to obtain cerium hydroxide precipitate, and washing the cerium hydroxide precipitate for multiple times by using pre-boiling ultrapure water.

(6) Preparation of cerium dioxide: and dissolving cerium hydroxide by using a hydrochloric acid solution subjected to distillation and purification for 3 times, wherein the acidity of the hydrochloric acid solution is 5.0mol/L to obtain a dissolved solution. Then adding oxalic acid solution with the mass concentration of oxalic acid of 70g/L for precipitation, and performing suction filtration to obtain rare earth oxalate precipitate. Then placing the rare earth oxalate precipitate in a muffle furnace for drying, and calcining for 3h at the high temperature of 850 ℃ to obtain a cerium dioxide product. Wherein oxalic acid in the oxalic acid solution is recrystallized for 3 times.

(7) The same procedure as in step (7) of example 1 gave the product analysis results shown in Table 2.

TABLE 2

Example 3

Example 3 is essentially the same as example 1, except that: the adsorption step in step (4) is as follows: the strip liquor was diluted with pure water until the pH of the strip liquor was 2, at which time the concentration of rare earth elements in the strip liquor was 5.0 g/L. And (3) placing the mixture in a high-level tank, adsorbing the stripping solution by using the extraction resin separation column, controlling the feeding flow rate of the stripping solution to be 0.3cm/min, monitoring the pH of the solution at the outlet of the extraction resin separation column and the change of the concentration of the rare earth element on line in real time, and stopping feeding until the rare earth element appears in the solution at the outlet of the exchange column. And then eluting the exchange column loaded with the stripping solution by pure water until the pH value of the outlet solution is 3, and stopping eluting to form the rare earth adsorption column. Wherein, the extraction resin separation column is a phosphorus-containing extraction resin separation column, and the column diameter is as follows: the column height is 1: 5.

the other steps and conditions were the same as in example 1, and the results of product analysis are shown in Table 3.

TABLE 3

Example 4:

example 4 is essentially the same as example 1, except that: in the adsorption step in the step (4), when the rare earth element appears in the solution at the outlet of the exchange column, the feeding is stopped, and the rare earth adsorption column is directly connected with the second extraction resin separation column in series without using pure water for washing.

The other steps and conditions were the same as in example 1, and the results of product analysis are shown in Table 4.

TABLE 4

Example 5

Example 5 is essentially the same as example 1, except that: in the leaching step of the step (4), after the adsorption column which has adsorbed and absorbed the rare earth is connected with the second treated exchange column in series, leaching the rare earth in the resin by using 0.03mol/L of low-acid solution, controlling the proper leaching speed to be 0.3cm/min, detecting the rare earth concentration of the solution at the outlet of the second exchange column on line, and when the solution at the outlet is the solutionWhen the concentration of the medium rare earth element is lower than 0.05g/L, the effluent solution directly enters a sewage treatment station for treatment; when the rare earth concentration of the outlet solution is more than 0.05g/L, the relative purity of cerium is less than 6N (Ce)⁴⁺When REO is less than 99.9999 percent), recovering leachate; when the relative purity of the rare earth in the outlet solution is more than or equal to 6N (Ce)⁴⁺REO is more than or equal to 99.9999 percent), and collecting leachate.

The other steps and conditions were the same as in example 1, and the results of product analysis are shown in Table 5.

TABLE 5

Example 6

Example 6 is essentially the same as example 1, except that: the precipitation step in the step (5) is as follows:

heating and concentrating the leaching solution until the concentration of the rare earth elements reaches 3g/L, precipitating the concentrated solution by using ammonia water with the excess of 1.0mol/L, then performing suction filtration to obtain cerium hydroxide precipitate, and washing the cerium hydroxide precipitate for multiple times by using pre-boiling ultrapure water.

Heating and concentrating the product solution to ensure that the rare earth concentration is 30g/L, adding ammonia water to control the pH value of the system to be 8 for precipitation, then carrying out suction filtration to obtain cerium hydroxide precipitate, and washing the cerium hydroxide precipitate for 1 time by using ultrapure water at the temperature of 60 ℃.

The other steps and conditions were the same as in example 1, and the results of product analysis are shown in Table 6.

TABLE 6

Example 7

Example 7 is essentially the same as example 1 except that: in the step (6), hydrochloric acid solution with acidity of 1.0mol/L is directly prepared by adopting analytically pure hydrochloric acid, and oxalic acid solution with mass concentration of 50g/L is prepared by adopting analytically pure oxalic acid for precipitation.

The other steps and conditions were the same as in example 1, and the results of product analysis are shown in Table 7.

TABLE 7

Comparative example 1

Comparative example 1 is substantially the same as example 1 except that: in the back extraction step of the step (3), a back extractant is prepared by adopting hydrochloric acid and pure water according to the concentration of 0.1 wt%.

The other steps and conditions were the same as in example 1, and the results of product analysis are shown in Table 8.

TABLE 8

The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.