A method for separating rubidium and cesium from rubidium-cesium enriched material by phase transformation

Abstract

The present invention relates to the field of extraction technology, and in particular to a method for separating rubidium and cesium from a rubidium-cesium enriched material through phase transformation. The method comprises the following steps: mixing the rubidium-cesium enriched material with water, adjusting the pH to 9.0-14.0, and then mixing and reacting with sodium phosphate to obtain a mixture; and performing solid-liquid separation on the obtained mixture to obtain a CsMgPO4 precipitate and a rubidium-containing solution. The present invention utilizes a rubidium-cesium enriched material as the subject, and uses phase transformation to separate rubidium and cesium from each other, while also enabling the recycling of anions. The cesium chloride obtained using the method provided by the present invention has a purity of 98% and a yield of 99%. The purity of the obtained rubidium chloride is 95% and the yield is 97%.

Description

Technical Field

[0001] The invention relates to the field of extraction technology, in particular to a method for separating rubidium and cesium from a rubidium-cesium enriched material through phase conversion. Background Art

[0002] Rubidium and cesium, two important rare-alkali metals, are widely used in new materials, new energy, biomedicine, and other fields. Rubidium and cesium are highly abundant in the Earth's crust but are extremely dispersed, often coexisting with other metals. Currently, rubidium and cesium resources are primarily found in salt lake brines and solid minerals such as lepidolite and spodumene. Regardless of their form, rubidium and cesium coexist in large quantities, making their selective separation difficult.

[0003] Currently, the main methods for separating rubidium and cesium from solutions include precipitation separation, solvent extraction, and adsorption separation. Precipitation methods can precipitate rubidium and cesium with sulfide salts, heteropolyacids, ferrocyanides, and polyhalides. Chemical precipitation offers advantages such as simplicity, ease of operation, low cost, and suitability for large-scale applications, but also has disadvantages such as the formation of secondary waste and difficulty in separation. Adsorption methods involve ion exchange between materials with specialized pore structures, such as Prussian blue and its analogs, clay minerals, phosphotungstic acid / silicotungstates, and zeolites, and rubidium-enriched solutions are obtained after desorption. The most widely used rubidium-cesium extractant for extraction is t-BAMBP. The extraction mechanism primarily utilizes a special organic extractant soluble in an organic solvent and an aqueous solution containing rubidium. Through ion exchange between the rubidium ions and the extractant, the rubidium ions are transported from the aqueous phase into the organic phase, where they are separated from the associated ions.

[0004] Chinese Patent 202011120620.0 proposes a method for extracting rubidium chloride from high-salinity rubidium-containing brine via extraction. U.S. Patent 4432893 proposes a precipitation-adsorption process for the decontamination of nuclear waste supernates, using sodium tetraphenylborate to precipitate cesium and potassium from high-level nuclear waste to purify cesium. Chinese Patent 201710615317.X proposes a method for separating and extracting rubidium and cesium from coal, using iodine chloride to form a precipitate containing rubidium and cesium, followed by t-BAMBP extraction to obtain high-purity rubidium chloride and cesium chloride. Chinese Patent 202110474179.4 proposes a method for extracting rubidium and cesium from complex underground brine, using tin tetrachloride precipitation to enrich rubidium and cesium, antimony trichloride to extract cesium, and then tin tetrachloride to extract rubidium. China Patent No. 201910583379 proposes a precipitation flotation separation system for rubidium and cesium in aqueous solution and its application. This precipitation flotation system uses phosphotungstate as a precipitant for the separation and purification of rubidium and cesium resources. China Patent No. 202010712906.1 proposes a method for extracting cesium and rubidium from lepidolite. A mixed alum of rubidium and cesium is calcined at high temperature to produce a sulfate solution enriched in rubidium and cesium. Cesium sulfate and rubidium sulfate with a purity of over 98% are then extracted through multi-stage extraction. The total recovery rate of cesium and rubidium is over 80%.

[0005] In summary, various precipitants can extract rubidium and cesium indiscriminately, but the subsequent separation of rubidium and cesium must rely on extraction. Therefore, the present invention addresses the problems existing in the prior art and proposes a method for separating rubidium and cesium from rubidium-cesium enriched materials through phase transformation. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a method for separating rubidium and cesium from a rubidium-cesium enriched material by phase transformation.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for separating rubidium and cesium from a rubidium-cesium enriched material by phase transformation, comprising the following steps:

[0009] 1) mixing the rubidium and cesium enriched material with water, adjusting the pH value to 9.0-14.0, and then mixing with sodium phosphate, stirring and reacting to obtain a mixture;

[0010] 2) separating the mixture obtained in step 1) into solid and liquid to obtain a CsMgPO4 precipitate and a rubidium-containing solution;

[0011] 3) mixing the CsMgPO4 precipitate obtained in step 2) with water, adjusting the pH to 9.0-14.0, and reacting to obtain a reactant;

[0012] 4) separating the reactant obtained in step 3) into solid and liquid to obtain a cesium-containing solution;

[0013] 5) extracting the cesium-containing solution obtained in step 4) using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a cesium-loaded organic phase;

[0014] 6) washing, stripping, and crystallizing the cesium-loaded organic phase obtained in step 5) to obtain cesium chloride;

[0015] 7) extracting the rubidium-containing solution obtained in step 2) using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a rubidium-loaded organic phase;

[0016] 8) washing, stripping, and crystallizing the organic phase loaded with rubidium obtained in step 7) to obtain rubidium chloride.

[0017] Preferably, the chemical formula of the rubidium-cesium enriched product in step 1) is (Cs / Rb / K)2MgFe(CN)6, and the mass percentage of the element content is: Cs 23.39%, Rb 18.2%, K4.7%, Mg 6.4%, and Fe 10.55%.

[0018] Preferably, the mass ratio of the rubidium and cesium enriched material to water in step 1) is 1:1 to 10;

[0019] The mass ratio of the rubidium and cesium enriched material to the sodium phosphate is 2-10:0.12-0.69.

[0020] Preferably, the stirring reaction time in step 1) is 30 minutes.

[0021] Preferably, after the solid-liquid separation in step 2), the obtained solid is dried to obtain a CsMgPO4 precipitate;

[0022] The drying temperature is 105° C. and the drying time is 120 min.

[0023] Preferably, the mass ratio of the CsMgPO4 precipitate to water in step 3) is 1:3;

[0024] The reaction was carried out under stirring for 30 min.

[0025] Preferably, the ratio of the organic phase to the aqueous phase extracted in step 5) or step 7) is 1 to 2:1.

[0026] Preferably, in step 5) or step 7), the volume ratio of t-BAMBP to sulfonated kerosene is 2:1.

[0027] Preferably, the extraction time in step 5) or step 7) is 3 to 5 minutes.

[0028] Preferably, the washing conditions in step 6) or step 8) include: mixing deionized water and the organic phase and oscillating for 1 to 5 minutes at an oscillation frequency of 100 to 400 r / min;

[0029] The stripping conditions include: mixing a hydrochloric acid solution with a concentration of 0.2 to 1 mol / L with the organic phase for 1 to 5 minutes; an oscillation frequency of 100 to 400 r / min;

[0030] The conditions for the crystallization separation include: heating the solution to 105° C. and boiling until cesium chloride crystals appear;

[0031] Beneficial effects of the present invention:

[0032] The present invention uses a rubidium-cesium enriched material as the target, separates the rubidium and cesium through phase transformation, and achieves the recycling of anions. The cesium chloride obtained using the method provided by the present invention has a purity of 98% and a yield of 99%, and the rubidium chloride obtained has a purity of 95% and a yield of 97%. DETAILED DESCRIPTION

[0033] The present invention provides a method for separating rubidium and cesium from a rubidium-cesium enriched material by phase transformation, comprising the following steps:

[0034] 1) mixing the rubidium and cesium enriched material with water, adjusting the pH value to 9.0-14.0, and then mixing with sodium phosphate, stirring and reacting to obtain a mixture;

[0035] 2) separating the mixture obtained in step 1) into solid and liquid to obtain a CsMgPO4 precipitate and a rubidium-containing solution;

[0036] 3) mixing the CsMgPO4 precipitate obtained in step 2) with water, adjusting the pH to 9.0-14.0, and reacting to obtain a reactant;

[0037] 4) separating the reactant obtained in step 3) into solid and liquid to obtain a cesium-containing solution;

[0038] 5) extracting the cesium-containing solution obtained in step 4) using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a cesium-loaded organic phase;

[0039] 6) washing, stripping, and crystallizing the cesium-loaded organic phase obtained in step 5) to obtain cesium chloride;

[0040] 7) extracting the rubidium-containing solution obtained in step 2) using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a rubidium-loaded organic phase;

[0041] 8) washing, stripping, and crystallizing the organic phase loaded with rubidium obtained in step 7) to obtain rubidium chloride.

[0042] The present invention mixes the rubidium-cesium enriched material with water, adjusts the pH value to 9.0-14.0, and then mixes and reacts with sodium phosphate under stirring to obtain a mixture. In the present invention, the chemical formula of the rubidium-cesium enriched material is (Cs / Rb / K)2MgFe(CN)6, and the mass percentage of the element content is: Cs 23.39%, Rb 18.2%, K4.7%, Mg 6.4%, Fe 10.55%. The present invention preferably uses sodium hydroxide to adjust the pH value. In the present invention, the mass ratio of the rubidium-cesium enriched material to water is preferably 1:10. In the present invention, the mass ratio of the rubidium-cesium enriched material to sodium phosphate is preferably 2-10:0.12-0.69. In the present invention, the stirring reaction time is preferably 30 minutes. In the present invention, the chemical reaction occurring in the stirring reaction is as follows:

[0043] (Cs / Rb / K)2MgFe(CN)6+PO4 3- →Rb + / K + +Fe(CN)6 4- +CsMgPO4.

[0044] The present invention separates the obtained mixture into solid and liquid to obtain CsMgPO4 precipitate and rubidium-containing solution. In the present invention, the rubidium-containing solution is mainly Rb + , K + and Fe(CN)6 4- The present invention has no particular limitation on solid-liquid separation, and conventional methods can be used, such as using filter paper for solid-liquid separation. In the present invention, after the solid-liquid separation, the obtained solid is preferably dried to obtain a CsMgPO4 precipitate. In the present invention, the drying temperature is preferably 105°C and the drying time is preferably 120 minutes.

[0045] In the present invention, the obtained CsMgPO4 precipitate is mixed with water, and the pH value is adjusted to 9.0-14.0 before reacting to obtain a reactant. In the present invention, sodium hydroxide is preferably used to adjust the pH value. In the present invention, the mass ratio of the CsMgPO4 precipitate to water is preferably 1:3. In the present invention, the reaction is preferably carried out under stirring, and the stirring time is preferably 30 minutes. In the present invention, the chemical reaction occurring in the reaction is as follows:

[0046] CsMgPO4+2OH-=Cs + +PO4 3- +Mg(OH)2↓.

[0047] The present invention separates the obtained reactants into solid and liquid to obtain a cesium-containing solution. In the present invention, the cesium-containing solution is mainly Cs + 、Na + and PO4 3- .

[0048] The cesium-containing solution obtained in the present invention is extracted using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a cesium-loaded organic phase. The sources of the t-BAMBP and sulfonated kerosene are not particularly limited; commercially available sources may be used. In the present invention, the ratio of the organic phase to the aqueous phase in the extraction step is preferably 1 to 2:1. In the present invention, the volume ratio of the t-BAMBP to the sulfonated kerosene is preferably 2:1. In the present invention, the extraction time is preferably 3 to 5 minutes.

[0049] The present invention washes, strips, crystallizes, and separates the obtained cesium-loaded organic phase to obtain cesium chloride. In the present invention, the washing conditions preferably include: mixing deionized water with the organic phase and oscillating for 1 to 5 minutes at an oscillation frequency of 100 to 400 r / min; the stripping conditions preferably include: mixing a hydrochloric acid solution with a concentration of 0.2 to 1 mol / L with the organic phase for 1 to 5 minutes at an oscillation frequency of 100 to 400 r / min; and the crystallization separation conditions preferably include: heating the solution to 105° C. and boiling until cesium chloride crystals appear.

[0050] The present invention extracts the obtained rubidium-containing solution using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a rubidium-loaded organic phase. The present invention does not specifically limit the sources of the t-BAMBP and sulfonated kerosene; conventional commercially available sources can be used. In the present invention, the ratio of the organic phase to the aqueous phase in the extraction step is preferably 1 to 2:1. In the present invention, the volume ratio of the t-BAMBP to the sulfonated kerosene is preferably 2:1. In the present invention, the extraction time is preferably 3 to 5 minutes.

[0051] The present invention washes, strips, crystallizes and separates the obtained rubidium-loaded organic phase to obtain rubidium chloride. In the present invention, the washing conditions preferably include: mixing deionized water with the organic phase and shaking for 1 to 5 minutes at an oscillation frequency of 100 to 400 r / min; the stripping conditions preferably include: mixing the organic phase with a hydrochloric acid solution having a concentration of 0.2 to 1 mol / L for 1 to 5 minutes at an oscillation frequency of 1 to 400 r / min; the crystallization separation conditions preferably include: heating the solution to 105°C and boiling until cesium chloride crystals appear.

[0052] In order to further illustrate the present invention, the present invention is described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0053] The rubidium-cesium enriched material in the embodiment of the present invention is mainly a mixture of rubidium, cesium, potassium, magnesium, and iron, and also includes non-metallic elements such as carbon and nitrogen. The chemical formula is (Cs / Rb / K)2MgFe(CN)6; the main element contents are shown in Table 1:

[0054] Table 1 Element contents of rubidium and cesium enriched materials

[0055] element Cs Rb K Mg Fe Mass percentage 23.39 18.2 4.7 6.4 10.55

[0056] Example 1

[0057] Take 2 g of rubidium and cesium enriched material, add deionized water with a mass ratio of 1:10, add sodium hydroxide until the pH value of the solution is 13.0, add 0.12 g of sodium phosphate to the mixture under continuous stirring, and after the addition is completed, continue stirring for 30 minutes, then filter with rapid filter paper, and after deionization washing, the solid precipitate is dried in an oven at 105°C for 120 minutes to obtain 1.24 g of CsMgPO4 solid, and rubidium and ferrocyanide ions are present in the solution.

[0058] The CsMgPO4 solid was added to deionized water at a mass ratio of 1:3, and sodium hydroxide was added to a pH of 13.0. After continuous stirring for 30 minutes, solid-liquid separation was performed to obtain 0.52g of magnesium hydroxide solid. Cesium, sodium, and phosphate were present in the solution. The solution was extracted with t-BAMBP as the extractant and sulfonated kerosene as the diluent for 2 minutes. The extraction time was 1:1 for the organic phase and the volume ratio of t-BAMBP to sulfonated kerosene was 2:1. The extraction captured 99% of the cesium in the organic phase, while the sodium and phosphate ions in the raffinate were returned to precipitate the cesium. The cesium-loaded organic phase was washed with deionized water for 2 minutes, stripped with 0.5 mol / L hydrochloric acid for 2 minutes, and crystallized to obtain 0.36g of cesium salt, with a cesium yield of 99%. The cesium chloride was tested to be approximately 98% pure.

[0059] The solution primarily contains rubidium and ferrocyanide ions, with a small amount of Cs ions. Using the same extraction method described above, 98% of the rubidium is captured in the organic phase. The potassium, sodium, and ferrocyanide ions in the raffinate can be dried and crystallized to recover ferrocyanide. After washing with deionized water for 2 minutes, back-extraction with 0.5 mol / L hydrochloric acid for 2 minutes, and crystallization, 0.23 g of solid is obtained, representing a 97% rubidium yield. Rubidium chloride is tested to be 95% pure.

[0060] Example 2

[0061] Take 2 g of rubidium and cesium enriched material, add deionized water with a mass ratio of 1:10, add sodium hydroxide until the pH value of the solution is 13.0, add 0.15 g of sodium phosphate to the mixture under continuous stirring, and after the addition is completed, continue stirring for 30 minutes, then filter with rapid filter paper, and after deionization washing, the solid precipitate is dried in an oven at 105°C for 120 minutes to obtain 1.37 g of CsMgPO4 solid, and rubidium and ferrocyanide ions are present in the solution.

[0062] Solid CsMgPO4 was added to deionized water at a mass ratio of 1:3, followed by sodium hydroxide to a pH of 13.0. Stirring was continued for 30 minutes, followed by solid-liquid separation to yield 0.45 g of magnesium hydroxide solid. Cesium, sodium, and phosphate were present in the solution. The solution was extracted with t-BAMBP as the extractant and sulfonated kerosene as the diluent for 2 minutes. The organic phase was extracted with a 1:1 ratio of the aqueous phase and a 2:1 volume ratio of t-BAMBP to sulfonated kerosene. This extraction captured 99% of the cesium in the organic phase, while the sodium and phosphate ions in the raffinate were returned to precipitate the cesium. The cesium-loaded organic phase was washed with deionized water for 2 minutes, followed by a 2-minute back extraction with 0.5 mol / L hydrochloric acid, resulting in crystallization and separation, yielding 0.44 g of cesium salt. The yield of cesium was 99%, and the resulting product was cesium chloride with a purity of approximately 98%.

[0063] The solution primarily contains rubidium and ferrocyanide ions, with a small amount of Cs ions. Using the same extraction method described above, 98% of the rubidium is captured in the organic phase. The potassium, sodium, and ferrocyanide ions in the raffinate can be dried and crystallized to recover ferrocyanide. After washing with deionized water for 2 minutes, back-extraction with 0.5 mol / L hydrochloric acid for 2 minutes, and crystallization, 0.28 g of solid is obtained, representing a 97% rubidium yield. Rubidium chloride is tested to be 95% pure.

[0064] Example 3

[0065] Take 5 g of rubidium and cesium enriched material, add deionized water with a mass ratio of 1:10, add sodium hydroxide until the pH value of the solution is 13.0, add 0.31 g of sodium phosphate to the mixture under continuous stirring, and after the addition is completed, continue stirring for 30 minutes, then filter with rapid filter paper, and after deionization washing, the solid precipitate is dried in an oven at 105°C for 120 minutes to obtain 2.71 g of CsMgPO4 solid, and rubidium and ferrocyanide ions are present in the solution.

[0066] Solid CsMgPO4 was added to deionized water at a mass ratio of 1:3, followed by sodium hydroxide until the pH reached 13.0. Stirring was continued for 30 minutes, followed by solid-liquid separation to yield 1.38 g of magnesium hydroxide solid. Cesium, sodium, and phosphate were present in the solution. The solution was extracted with t-BAMBP as the extractant and sulfonated kerosene as the diluent for 2 minutes. The organic phase was extracted with a 1:1 ratio of the aqueous phase and a 2:1 volume ratio of t-BAMBP to sulfonated kerosene. This extraction captured 99% of the cesium in the organic phase, while the sodium and phosphate ions in the raffinate were returned to precipitate the cesium. The cesium-loaded organic phase was washed with deionized water for 2 minutes, followed by a 2-minute back extraction with 0.5 mol / L hydrochloric acid, resulting in crystallization and separation, yielding 0.97 g of cesium salt. The yield of cesium was 99%, and the resulting product was cesium chloride with a purity of approximately 98%.

[0067] The solution primarily contains rubidium and ferrocyanide ions, with a small amount of Cs ions. Using the same extraction method described above, 98% of the rubidium is captured in the organic phase. The potassium, sodium, and ferrocyanide ions in the raffinate can be dried and crystallized to recover ferrocyanide. After washing with deionized water for 2 minutes, back-extraction with 0.5 mol / L hydrochloric acid for 2 minutes, and crystallization, 0.55 g of solid is obtained, representing a 97% rubidium yield. Rubidium chloride is tested to be 95% pure.

[0068] Example 4

[0069] Take 10g of rubidium and cesium enriched material, add deionized water with a mass ratio of 1:10, add sodium hydroxide until the pH value of the solution is 13.0, add 0.69g of sodium phosphate to the mixture under continuous stirring, and after the addition is completed, continue stirring for 30 minutes, then filter with rapid filter paper, and after deionization washing, the solid precipitate is dried in an oven at 105°C for 120 minutes to obtain 5.52g of CsMgPO4 solid, and rubidium and ferrocyanide ions are present in the solution.

[0070] Solid CsMgPO4 was added to deionized water at a mass ratio of 1:3, followed by sodium hydroxide to a pH of 13.0. Stirring was continued for 30 minutes, followed by solid-liquid separation, yielding 2.31 g of magnesium hydroxide solid. Cesium, sodium, and phosphate were present in the solution. The solution was extracted with t-BAMBP as the extractant and sulfonated kerosene as the diluent for 2 minutes. The organic phase was extracted with a 1:1 ratio of the aqueous phase and a 2:1 volume ratio of t-BAMBP to sulfonated kerosene. This extraction captured 99% of the cesium in the organic phase, while the sodium and phosphate ions in the raffinate were returned to precipitate the cesium. The cesium-loaded organic phase was washed with deionized water for 2 minutes, followed by a 2-minute back extraction with 0.5 mol / L hydrochloric acid, resulting in 1.89 g of cesium salt, a 99% cesium yield. The resulting cesium chloride was tested to be approximately 98% pure.

[0071] The solution primarily contains rubidium and ferrocyanide ions, with a small amount of Cs ions. Using the same extraction method described above, 98% of the rubidium is captured in the organic phase. The potassium, sodium, and ferrocyanide ions in the raffinate can be dried and crystallized to recover ferrocyanide. After washing with deionized water for 2 minutes, back-extraction with 0.5 mol / L hydrochloric acid for 2 minutes, and crystallization, 1.21 g of solid was obtained, representing a 97% rubidium yield. Rubidium chloride was tested to be 95% pure.

[0072] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for separating rubidium and cesium from a rubidium-cesium enriched material by phase transformation, characterized in that: The following steps are involved: 1) mixing the rubidium and cesium enriched material with water, adjusting the pH value to 9.0-14.0, and then mixing with sodium phosphate and stirring to react to obtain a mixture; 2) separating the mixture obtained in step 1) into solid and liquid to obtain a CsMgPO4 precipitate and a rubidium-containing solution; 3) mixing the CsMgPO4 precipitate obtained in step 2) with water, adjusting the pH value to 9.0-14.0, and reacting to obtain a reactant; 4) separating the reactant obtained in step 3) into solid and liquid to obtain a cesium-containing solution; 5) extracting the cesium-containing solution obtained in step 4) using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a cesium-loaded organic phase; 6) washing, stripping, and crystallizing the cesium-loaded organic phase obtained in step 5) to obtain cesium chloride; 7) extracting the rubidium-containing solution obtained in step 2) using t-BAMBP as an extractant and sulfonated kerosene as a diluent to obtain a rubidium-loaded organic phase; 8) washing, stripping, and crystallizing the rubidium-loaded organic phase obtained in step 7) to obtain rubidium chloride; The chemical formula of the rubidium-cesium enriched product in step 1) is (Cs / Rb / K)2MgFe(CN)6, and the mass percentage of the elements is: Cs 23.39%, Rb 18.2%, K 4.7%, Mg 6.4%, and Fe 10.55%.

2. The method according to claim 1, characterized in that In the step 1), the mass ratio of the rubidium and cesium enriched material to water is 1:1-10; The mass ratio of the rubidium and cesium enriched material to the sodium phosphate is 2-10:0.12-0.

69.

3. The method according to claim 1, characterized in that The stirring reaction time in step 1) is 30 minutes.

4. The method according to claim 1, wherein In step 2), the solid obtained after solid-liquid separation is dried to obtain CsMgPO4 precipitate; The drying temperature is 105° C. and the drying time is 120 min.

5. The method according to claim 1, wherein In step 3), the mass ratio of CsMgPO4 precipitate to water is 1:3; The reaction was carried out under stirring for 30 min.

6. The method according to claim 1, characterized in that The ratio of the organic phase to the aqueous phase in the extraction of step 5) or step 7) is 1-2:

1.

7. The method according to claim 1, characterized in that In step 5) or step 7), the volume ratio of t-BAMBP to sulfonated kerosene is 2:

1.

8. The method according to claim 1, characterized in that The extraction time in step 5) or step 7) is 3 to 5 minutes.

9. The method according to claim 1, characterized in that The washing conditions of step 6) or step 8) include: mixing deionized water and the organic phase and shaking for 1 to 5 minutes at an oscillation frequency of 100 to 400 r / min; The stripping conditions include: mixing the organic phase with a hydrochloric acid solution having a concentration of 0.2 to 1 mol / L for 2 minutes; an oscillation frequency of 100 to 400 r / min; The conditions for the crystallization separation include: heating the solution to 105° C. and boiling until cesium chloride crystals appear.