阅读说明：本技术 一种从稀土废渣中提取制备核纯级ThO2粉末的方法 (Method for extracting and preparing nuclear pure ThO from rare earth waste residues2Method for producing powder ) 是由 张凡 李涛 刘伟 郭波龙 盖石琨 王昱人 郝治国 于晓波 于 2020-11-20 设计创作，主要内容包括：本发明属于放射性废物处理技术领域,具体涉及一种从稀土废渣中提取制备核纯级ThO-2粉末的方法,对稀土废渣进行碱化处理,不仅可以实现钍元素与部分杂质元素的初步分离,还能有效解决设备腐蚀问题,同时生成的氢氧化钍易于转化成硝酸钍溶液,进行下一步萃取纯化处理。本方法采用离心萃取技术对硝酸钍进行萃取纯化,具有回收率高、可连续操作、能耗低等特点,实现了钍元素与其他稀土元素的高效分离,因此本发明对从稀土废渣中提取制备核纯级ThO-2粉末具有重要意义。(The invention belongs to the technical field of radioactive waste treatment, and particularly relates to a method for extracting and preparing nuclear pure ThO from rare earth waste residues 2 The powder method is used for alkalizing the rare earth waste residues, so that preliminary separation of thorium elements and partial impurity elements can be realized, the problem of equipment corrosion can be effectively solved, and meanwhile, the generated thorium hydroxide is easily converted into a thorium nitrate solution for next extraction and purification treatment. The method adopts centrifugal extraction technology to carry out nitric acid treatmentThe thorium is extracted and purified, the method has the characteristics of high recovery rate, continuous operation, low energy consumption and the like, and realizes the high-efficiency separation of the thorium element and other rare earth elements, so that the method is used for extracting and preparing the nuclear pure ThO from the rare earth waste residue 2 Powders are of great significance.)

1. Method for extracting and preparing nuclear pure ThO from rare earth waste residues₂A method of powdering, characterized by:

the method comprises the following steps of firstly, pretreating the rare earth waste residue, determining the components of the rare earth waste residue, and adding water to make slurry of the rare earth waste residue;

step two, heating the waste residue slurry to a proper temperature, adding alkali liquor to perform an alkalization displacement reaction to obtain a thorium hydroxide filter cake, and filtering and washing the filter cake;

performing acid dissolution on the thorium hydroxide filter cake to obtain a thorium nitrate solution, and adding an oxidant to perform cerium ion reduction conversion treatment;

screening a proper extracting agent, removing uranium ions in the solution by adopting a centrifugal extraction technology, and then performing extraction and back extraction of thorium ions;

step five, after extraction and purification, adding a precipitator to precipitate, dry and roast thorium ions to prepare the generated nuclear pure-grade ThO₂And (3) powder.

2. The method of claim 1, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: in the first step, water is added into the rare earth waste residue to prepare slurry, and the adding amount of the water is adjusted to be within the range of 5-12L/kg of the waste residue.

3. A process for reclaiming the rare-earth elements contained in the waste material of claim 1Extracting and preparing nuclear pure ThO from slag₂A method of powdering, characterized by: in the step two alkalization displacement process, sodium hydroxide, potassium hydroxide and ammonia water are selected to carry out alkaline displacement reaction.

4. The method of claim 3, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: in the second alkalization and replacement process, the concentration of an alkaline solution is adjusted to 2.5-4 mol/L, and the reaction temperature is controlled within the range of 60-90 ℃;

in the alkalization replacement process, the adding amount of an alkaline solution is 120-200% of the amount required by normal reaction;

in the alkalization displacement process, the reaction time of displacement by using alkali liquor is not less than 3 h;

in the alkalization replacement process, after replacement is finished, the precipitate is filtered by using nylon filter cloth.

5. The method of claim 3, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: in the washing process of the thorium dihydroxide filter cake, deionized water is used for hot washing, and the washing temperature of the deionized water is 50-70 ℃;

in the washing process of the thorium hydroxide filter cake, the washing times of deionized water are not less than 3-5 times, and the washing dosage is 10-15L/kg of precipitate every time.

6. The method of claim 1, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: in the thorium hydroxide filter cake dissolving process, nitric acid is selected as an acid solution, and the dissolving temperature is controlled within the range of 60-90 ℃.

7. The method of claim 1, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: in the preparation process of the thorium trinitrate solution, the concentration of thorium ions in the solution is adjusted to be 50-300 g/L, and the acidity of the solution is adjusted to be 1-4 mol/L.

8. The method of claim 1, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: step three, during the reduction and conversion process of cerium ions, H is selected₂O₂Reductive conversion as an oxidant, H₂O₂The adding amount is 3-12% of the volume of the thorium nitrate solution.

9. The method of claim 1, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by: selecting carboxylic acid, sulfonic acid, organic phosphoric acid, crown ether and primary amine extractant to perform screening test in the extractant optimization process in the fourth step; in the extraction agent optimization process, tributyl phosphate is selected as an extraction agent, and kerosene is adopted as a diluent;

in the extraction process, extraction equipment such as a mixer-settler, an ion extractor and a jet extractor is selected, the extraction material is stainless steel, PP, PMMA and the like, and the treatment capacity of the extraction equipment is 1-10L/h;

in the extraction and back extraction processes, a centrifugal extractor is preferably selected, 10-20 stages of extractors are adopted for series coupling, and the rotation number of the extractors is selected to be 3000-6000 r/min;

in the uranium removing process of the thorium nitrate solution, the extraction system is 3-10% of TBP-kerosene;

in the extraction process of the thorium ions, the extraction system is 20-40% of TBP-kerosene;

in the extraction process, a countercurrent extraction mode is adopted, and the flow ratio of a water phase inlet to an organic phase inlet is 1: 2-4: 1;

in the washing process, 0.5-1.5 mol/L nitric acid solution is selected as washing liquid, and the using amount of the washing liquid is 0.5-1 time of the volume of the loaded organic phase;

in the back extraction process, hot water is selected as a back extractant, and the temperature of the hot water is controlled to be 55-85 ℃;

in the back extraction process, the flow ratio of a water phase inlet to an organic phase inlet in the experiment process is 1: 3-2: 1;

and in the back extraction process and the experimental process, liquid at the water phase outlet is collected, and the impurity content is analyzed and detected.

10. The method of claim 1, wherein the nuclear pure ThO is prepared by extracting rare earth waste residue₂A method of powdering, characterized by:

in the precipitation process of the thorium ions in the step five, oxalic acid, hydrogen peroxide and NaOH can be selected to carry out precipitation of the thorium ions;

in the precipitation process of the thorium ions, the precipitation temperature is controlled within the range of 60-90 ℃, precipitates are filtered while being hot, and are washed for 3 times by deionized water;

in the drying and roasting process, a muffle furnace is selected for drying and roasting, the drying temperature is 250-350 ℃, the time is 2-3 hours, the roasting temperature is 700-850 ℃, and the time is 1-2 hours.

Technical Field

The invention belongs to the technical field of radioactive waste treatment, and particularly relates to a method for extracting and preparing nuclear pure ThO from rare earth waste residues₂A method of powdering.

Background

In the rare earth dressing and smelting process, thorium is mined as an accompanying object, the utilization rate of thorium resources is low, a large amount of thorium resources are finally stored separately in the form of rare earth waste residues, the rare earth waste residues can cause radioactive pollution, precious thorium resources can be seriously wasted, and therefore thorium needs to be recycled.

In the traditional recovery process, the ThO is extracted and prepared by adopting the processes of acid mixing, extraction, precipitation, burning and the like₂The process has the advantages that the dosage of reagents is large, the equipment is easy to corrode by using the fluorine-containing acid liquid, the amount of radioactive wastewater generated is large, and the problems of low recovery efficiency, high energy consumption and the like of the traditional extraction equipment exist.

Disclosure of Invention

Aiming at the defects, the invention aims to provide a method for extracting and preparing nuclear pure ThO from rare earth waste residues₂The powder method is used for alkalizing the rare earth waste residues, so that preliminary separation of thorium elements and partial impurity elements can be realized, the problem of equipment corrosion can be effectively solved, and meanwhile, the generated thorium hydroxide is easily converted into a thorium nitrate solution for next extraction and purification treatment. The method adopts centrifugal extraction technology to extract and purify thorium nitrate, and has recovery rateHigh efficiency separation of thorium element from other rare earth elements, continuous operation, low energy consumption, etc. therefore, the invention extracts and prepares nuclear pure ThO from rare earth waste residue₂Powders are of great significance.

The technical scheme of the invention is as follows:

method for extracting and preparing nuclear pure ThO from rare earth waste residues₂The powder preparation method comprises the following steps of firstly, pretreating the rare earth waste residue, determining the components of the rare earth waste residue, and adding water to make slurry of the rare earth waste residue;

step two, heating the waste residue slurry to a proper temperature, adding alkali liquor to perform an alkalization displacement reaction to obtain a thorium hydroxide filter cake, and filtering and washing the filter cake;

performing acid dissolution on the thorium hydroxide filter cake to obtain a thorium nitrate solution, and adding an oxidant to perform cerium ion reduction conversion treatment;

screening a proper extracting agent, removing uranium ions in the solution by adopting a centrifugal extraction technology, and then performing extraction and back extraction of thorium ions;

step five, after extraction and purification, adding a precipitator to precipitate, dry and roast thorium ions to prepare the generated nuclear pure-grade ThO₂And (3) powder.

In the first step, water is added into the rare earth waste residue to prepare slurry, and the adding amount of the water is adjusted to be within the range of 5-12L/kg of the waste residue.

In the step two alkalization displacement process, sodium hydroxide, potassium hydroxide and ammonia water are selected to carry out alkaline displacement reaction.

In the second alkalization and replacement process, the concentration of an alkaline solution is adjusted to 2.5-4 mol/L, and the reaction temperature is controlled within the range of 60-90 ℃;

in the alkalization replacement process, the adding amount of an alkaline solution is 120-200% of the amount required by normal reaction;

in the alkalization displacement process, the reaction time of displacement by using alkali liquor is not less than 3 h;

in the alkalization replacement process, after replacement is finished, the precipitate is filtered by using nylon filter cloth.

In the washing process of the thorium dihydroxide filter cake, deionized water is used for hot washing, and the washing temperature of the deionized water is 50-70 ℃;

in the washing process of the thorium hydroxide filter cake, the washing times of deionized water are not less than 3-5 times, and the washing dosage is 10-15L/kg of precipitate every time.

In the thorium hydroxide filter cake dissolving process, nitric acid is selected as an acid solution, and the dissolving temperature is controlled within the range of 60-90 ℃.

In the preparation process of the thorium trinitrate solution, the concentration of thorium ions in the solution is adjusted to be 50-300 g/L, and the acidity of the solution is adjusted to be 1-4 mol/L.

Step three, during the reduction and conversion process of cerium ions, H is selected₂O₂Reductive conversion as an oxidant, H₂O₂The adding amount is 3-12% of the volume of the thorium nitrate solution.

Selecting carboxylic acid, sulfonic acid, organic phosphoric acid, crown ether and primary amine extractant to perform screening test in the extractant optimization process in the fourth step; in the extraction agent optimization process, tributyl phosphate is selected as an extraction agent, and kerosene is adopted as a diluent;

in the extraction process, extraction equipment such as a mixer-settler, an ion extractor and a jet extractor is selected, the extraction material is stainless steel, PP, PMMA and the like, and the treatment capacity of the extraction equipment is 1-10L/h;

in the extraction and back extraction processes, a centrifugal extractor is preferably selected, 10-20 stages of extractors are adopted for series coupling, and the rotation number of the extractors is selected to be 3000-6000 r/min;

in the uranium removing process of the thorium nitrate solution, the extraction system is 3-10% of TBP-kerosene;

in the extraction process of the thorium ions, the extraction system is 20-40% of TBP-kerosene;

in the extraction process, a countercurrent extraction mode is adopted, and the flow ratio of a water phase inlet to an organic phase inlet is 1: 2-4: 1;

in the washing process, 0.5-1.5 mol/L nitric acid solution is selected as washing liquid, and the using amount of the washing liquid is 0.5-1 time of the volume of the loaded organic phase;

in the back extraction process, hot water is selected as a back extractant, and the temperature of the hot water is controlled to be 55-85 ℃;

in the back extraction process, the flow ratio of a water phase inlet to an organic phase inlet in the experiment process is 1: 3-2: 1;

and in the back extraction process and the experimental process, liquid at the water phase outlet is collected, and the impurity content is analyzed and detected.

In the precipitation process of the thorium ions in the step five, oxalic acid, hydrogen peroxide and NaOH can be selected to carry out precipitation of the thorium ions;

in the precipitation process of the thorium ions, the precipitation temperature is controlled within the range of 60-90 ℃, precipitates are filtered while being hot, and are washed for 3 times by deionized water;

in the drying and roasting process, a muffle furnace is selected for drying and roasting, the drying temperature is 250-350 ℃, the time is 2-3 hours, the roasting temperature is 700-850 ℃, and the time is 1-2 hours.

The invention has the beneficial effects that:

the method adopts the technologies of alkalization treatment, centrifugal extraction and the like to realize the treatment and purification processes of the rare earth waste residue, has simple process flow, less reagent consumption and less corrosion to equipment, is easy to extract thorium element from the rare earth waste residue, has good extraction and back extraction effects by using the centrifugal extraction technology, has no impurity introduction in the processes of precipitation and calcination, can prepare thorium dioxide powder with the purity of over 99.9 percent, and has lower content of radioactive elements after the extraction tail water is treated, thereby meeting the emission standard.

Drawings

FIG. 1 is a schematic flow diagram of the process of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

FromExtraction and preparation of nuclear pure ThO from rare earth waste residue₂The powder preparation method comprises the following specific steps:

the method comprises the following steps of firstly, pretreating the rare earth waste residue, determining the components of the rare earth waste residue, and adding water to make slurry of the rare earth waste residue;

step two, heating the waste residue slurry to a proper temperature, adding alkali liquor to perform an alkalization displacement reaction to obtain a thorium hydroxide filter cake, and filtering and washing the filter cake;

performing acid dissolution on the thorium hydroxide filter cake to obtain a thorium nitrate solution, and adding an oxidant to perform cerium ion reduction conversion treatment;

screening a proper extracting agent, removing uranium ions in the solution by adopting a centrifugal extraction technology, and then performing extraction and back extraction of thorium ions;

step five, after extraction and purification, adding a precipitator to precipitate, dry and roast thorium ions to prepare the generated nuclear pure-grade ThO₂And (3) powder.

Step one, adding water into the rare earth waste residues to prepare slurry, wherein the adding amount of the water is adjusted to be within the range of 5-12L/kg of the waste residues.

And step two, in the alkalization replacement process, sodium hydroxide, potassium hydroxide, ammonia water and the like are selected for carrying out alkaline replacement reaction.

And step two, in the alkalization replacement process, the concentration of the alkaline solution is adjusted to 2.5-4 mol/L, and the reaction temperature is controlled within the range of 60-90 ℃.

And step two, in the alkalization and replacement process, the adding amount of the alkaline solution is 120-200% of the amount required by the normal reaction.

In the alkalization and replacement process, the reaction time of replacement by using alkali liquor is not less than 3 h.

And step two, in the alkalization and replacement process, filtering the precipitate by using nylon filter cloth after replacement is finished.

And step two, washing the thorium hydroxide filter cake by using deionized water at 50-70 ℃ while the thorium hydroxide filter cake is hot.

And in the washing process of the thorium hydroxide filter cake in the second step, the washing times of deionized water are not less than 3-5 times, and the washing dosage is 10-15L/kg of precipitate every time.

In the thorium hydroxide filter cake dissolving process, nitric acid is preferably used as an acid solution, and the dissolving temperature is controlled within the range of 60-90 ℃.

And step three, in the preparation process of the thorium nitrate solution, the concentration of thorium ions in the solution is adjusted to be within the range of 50-300 g/L, and the acidity of the solution is adjusted to be within the range of 1-4 mol/L.

Step three the cerium ion reduction conversion process, preferably H₂O₂Reductive conversion as an oxidant, H₂O₂The adding amount is 3-12% of the volume of the thorium nitrate solution.

And step four, selecting the extracting agents such as carboxylic acid, sulfonic acid, organic phosphoric acid, crown ether, primary amine and the like for screening test in the extracting agent optimization process.

And step four, optimizing the extractant process, and finally selecting tributyl phosphate (TBP) as the extractant and adopting kerosene as the diluent.

And step four, in the extraction process, extraction equipment such as a mixer-settler, an ion extractor and a jet extractor is selected, the extraction material is stainless steel, PP, PMMA and the like, and the treatment capacity of the extraction equipment is 1-10L/h.

And step four, in the extraction and back extraction processes, a centrifugal extractor is preferably selected, 10-20 stages of extractors are adopted for series coupling, and the rotation number of the extractors is selected to be 3000-6000 r/min.

And step four, in the uranium removing process of the thorium nitrate solution, the extraction system is 3% -10% of TBP-kerosene.

And step four, in the extraction process of the thorium ions, the extraction system is 20-40% of TBP-kerosene.

And step four, in the extraction process, a countercurrent extraction mode is adopted, and the flow ratio of a water phase inlet to an organic phase inlet is 1: 2-4: 1.

And step four, in the washing process, 0.5-1.5 mol/L nitric acid solution is selected as a washing liquid, and the using amount of the washing liquid is 0.5-1 time of the volume of the loaded organic phase.

And step four, in the back extraction process, hot water is selected as a back extractant, and the temperature of the hot water is controlled to be 55-85 ℃.

And step four, performing a back extraction process, wherein the flow ratio of the water phase inlet to the organic phase inlet in the experimental process is 1: 3-2: 1.

And step four, a back extraction process, namely collecting liquid at the water phase outlet in the experimental process, and analyzing and detecting the content of impurities.

And fifthly, in the precipitation process of the thorium ions, oxalic acid, hydrogen peroxide, NaOH and the like can be selected for precipitation of the thorium ions.

And fifthly, in the precipitation process of the thorium ions, the precipitation temperature is controlled within the range of 60-90 ℃, the precipitate is filtered while being hot, and is washed for 3 times by deionized water.

And fifthly, in the drying and roasting process, a muffle furnace is selected for drying and roasting, the drying temperature is 250-350 ℃, the time is 2-3 hours, the roasting temperature is 700-850 ℃, and the time is 1-2 hours.

Example 1:

step one, pretreating the rare earth waste residues, measuring the components of the rare earth waste residues, adding 5-12L of deionized water into each kilogram of waste residues to make slurry, controlling the temperature of the slurry of the waste residues to be 60-90 ℃,

and step two, adding 2.5-4 mol/L alkali liquor to perform an alkaline displacement reaction, wherein the addition amount of the alkali liquor is 120-180% of the normal reaction amount, and the displacement reaction is not less than 3 h. And washing the generated thorium hydroxide filter cake at 50-70 ℃ for not less than 3-5 times.

And step three, dissolving the thorium hydroxide filter cake by using nitric acid, controlling the dissolving temperature to be 60-90 ℃, and adjusting the thorium ion concentration in the solution to be 50-300 g/L and the acidity to be 1-4 mol/L. Adding H with the volume of 3-12 percent into thorium nitrate solution₂O₂Reducing and converting cerium ions to obtain an extract stock solution for later use.

And step four, selecting tributyl phosphate as an extraction medium, using kerosene as an extraction diluent, firstly using TBP-kerosene with the volume ratio of 3-10% to perform solution uranium removal operation, then using TBP-kerosene with the volume ratio of 20-40% to perform thorium extraction operation, adopting a countercurrent extraction mode in the two extraction processes, adopting 10-20 stages of extractors to be coupled in series, selecting the revolution of the extractors to be 3000-6000 r/min, and setting the flow ratio of an aqueous phase inlet to an organic phase inlet to be 1: 2-4: 1. Collecting the organic phase loaded with thorium ions for washing treatment, wherein the concentration of nitric acid in a washing liquid is 0.5-1.5 mol/L, and the using amount of the washing liquid is 0.5-1 time of the volume of the loaded organic phase. And (3) carrying out back extraction treatment on the loaded organic phase by adopting hot water at the temperature of 55-85 ℃, wherein the ratio of the back extraction agent to the loaded organic phase is 1: 3-2: 1, and collecting a water phase outlet solution.

And step five, selecting oxalic acid, hydrogen peroxide, NaOH and the like to precipitate the strip liquor, controlling the temperature of the precipitation solution at 60-90 ℃, filtering the hot precipitate, and washing the hot precipitate for 3 times by using deionized water. And (3) drying and calcining the thorium dioxide filter cake by using a muffle furnace, wherein the drying temperature is 250-350 ℃, the time is 2-3 hours, the calcining temperature is 700-850 ℃, and the time is 1-2 hours.

Example 2:

step one, pretreating the rare earth waste residue, measuring the components of the rare earth waste residue, pulping according to the proportion that 7L of deionized water is added into each kilogram of waste residue,

and step two, controlling the temperature of the waste residue slurry at 70 ℃, adding 3mol/L sodium hydroxide solution to perform alkaline replacement reaction, and performing the reaction for 2 hours to obtain a thorium hydroxide filter cake. Washing the thorium hydroxide filter cake with deionized water at 60 ℃ for 4 times.

Step three, adding nitric acid to dissolve thorium hydroxide filter cakes, controlling the dissolving temperature at 80 ℃, regulating the thorium ion concentration to 150g/L and the acidity to 2mol/L, and adding 5% H₂O₂Reducing and converting cerium ions to obtain an extract stock solution for later use.

And step four, firstly preparing TBP-kerosene with the volume ratio of 5%, carrying out solution uranium removal operation, then preparing TBP-kerosene with the volume ratio of 30% to carry out thorium extraction operation, adopting a countercurrent extraction mode in the two extraction processes, adopting 15-stage extractors to be coupled in series, selecting the revolution of the extractors to be 4000r/min, and setting the flow ratio of a water phase inlet to an organic phase inlet to be 1: 1.5. Collecting the organic phase loaded with thorium ions for washing treatment, wherein the concentration of nitric acid in a washing liquid is 0.8mol/L, and the using amount of the washing liquid is 0.8 times of the volume of the loaded organic phase. And (3) carrying out back extraction treatment on the loaded organic phase by using hot water at the temperature of 75 ℃, wherein the flow ratio of a back extraction agent to the loaded organic phase is 1:1.8, and collecting a water phase outlet solution.

And step five, selecting oxalic acid, hydrogen peroxide, NaOH and the like to precipitate the strip liquor, controlling the temperature of the precipitation solution at 70 ℃, filtering the hot precipitate, and washing the hot precipitate for 3 times by using deionized water. And (3) drying and calcining the thorium dioxide filter cake by using a muffle furnace, wherein the drying temperature is 260 ℃, the time is 2 hours, the roasting temperature is 750 ℃, and the time is 1.2 hours.

Example 3:

step one, pretreating the rare earth waste residues, measuring the components of the rare earth waste residues, pulping according to the proportion that 10L of deionized water is added into each kilogram of waste residues, controlling the temperature of waste residue pulp liquid at 80 ℃,

and step two, adding 2.5mol/L sodium hydroxide solution to perform alkaline replacement reaction for 3 hours to obtain a thorium hydroxide filter cake. Washing the thorium hydroxide filter cake for 3 times by using deionized water at 70 ℃.

Step three, adding nitric acid to dissolve thorium hydroxide filter cakes, controlling the dissolving temperature at 75 ℃, regulating the thorium ion concentration to 200g/L and the acidity to 2.5mol/L, and adding 8% H₂O₂Reducing and converting cerium ions to obtain an extract stock solution for later use.

And step four, firstly preparing 9% TBP-kerosene, carrying out solution uranium removal operation, then preparing 40% TBP-kerosene, carrying out thorium extraction operation, adopting a countercurrent extraction mode in the two extraction processes, adopting 16-stage extractors for series coupling, selecting the rotation number of the extractors to be 4500r/min, and setting the flow ratio of the water phase inlet to the organic phase inlet to be 1: 2.2. Collecting the organic phase loaded with thorium ions for washing treatment, wherein the concentration of nitric acid in a washing liquid is 0.5mol/L, and the using amount of the washing liquid is 1 time of the volume of the loaded organic phase. And (3) carrying out back extraction treatment on the loaded organic phase by adopting hot water at 70 ℃, wherein the flow ratio of a back extraction agent to the loaded organic phase is 1:1, and collecting a water phase outlet solution.

And step five, selecting oxalic acid, hydrogen peroxide, NaOH and the like to precipitate the strip liquor, controlling the temperature of the precipitation solution at 80 ℃, filtering the hot precipitate, and washing the hot precipitate for 3 times by using deionized water. And (3) drying and calcining the thorium dioxide filter cake by using a muffle furnace, wherein the drying temperature is 300 ℃, the time is 2.2 hours, the calcining temperature is 800 ℃, and the time is 1 hour.

In the drawings of the disclosed embodiments of the invention, only methods related to the disclosed embodiments are referred to, other methods can refer to common design, and the same embodiment and different embodiments of the invention can be combined with each other without conflict;

the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included in the scope of the present invention.