Method for preparing cesium nitrate from caesium-lilith

Abstract

The application provides a method for preparing cesium nitrate from alkali-dissolved cesium tourmaline, and belongs to the technical field of smelting of cesium ores. 3+ The cesium-rich residue is subjected to acid leaching to obtain an acid leaching solution, the pH value of the acid leaching solution is adjusted to remove Al The cesium nitrate solution is concentrated, cooled and crystallized, and then subjected to solid-liquid separation to obtain cesium nitrate crude product, and the cesium nitrate crude product is recrystallized and dried to obtain cesium nitrate finished product. The method for preparing cesium nitrate through alkali-dissolution realizes full utilization of cesium resources in cesium tourmaline, and high-value cesium nitrate product is obtained. The obtained product has high purity, raw materials are simple and easy to obtain, the environment is relatively friendly, the operation cost is relatively low, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of cesium ore smelting technology, and in particular to a method for preparing cesium nitrate by alkali dissolution of cesium garnet. Background Technology

[0002] Cesium nitrate, an important alkali metal nitrate with the molecular formula CsNO3, is an inorganic compound that is a white crystalline powder at room temperature and pressure. It is hygroscopic and, due to its chemical properties, is often used as a basic raw material for producing high-purity cesium salts. It is also used in organic industrial catalysts and is one of the main varieties in the cesium salt market. The demand for cesium nitrate has shown a steady annual growth trend, especially in the aerospace field, where it plays a crucial role as a key material in propellants, fuels, and optical components, resulting in particularly strong market demand.

[0003] Current cesium nitrate preparation processes generally employ nitric acid neutralization and ion exchange methods. The mainstream process involves using ion exchange resins to convert cesium sulfate conversion solution into high-purity cesium nitrate. However, this method is complex, costly, and inefficient. Furthermore, the recovery rate of cesium garnet from sulfuric acid leaching in traditional processes is only 90%, resulting in a high cesium loss rate. Therefore, providing a highly efficient, high-purity, simple, and low-cost method for cesium nitrate preparation is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing cesium nitrate by alkali dissolution of cesium garnet. This method solves the problems of high cesium element loss rate, complex process flow, high cost and low efficiency in traditional processes.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing cesium nitrate by alkali dissolution of cesium garnet, comprising the following steps: 1) Mix cesium garnet concentrate powder with alkaline solution, perform alkaline leaching, and separate to obtain cesium-rich slag and recycled alkaline solution; 2) The cesium-rich slag is mixed with acid and subjected to acid leaching to obtain an acid leaching solution; 3) Add a pH adjuster to the acid leaching solution until the final pH value is 7.5~8.5, perform aluminum precipitation, and then filter under pressure to obtain a cesium nitrate solution; 4) The cesium nitrate solution is concentrated under negative pressure, and the resulting concentrate is cooled and crystallized, then separated to obtain crude cesium nitrate and concentrated mother liquor; 5) The crude cesium nitrate was recrystallized and dried sequentially to obtain cesium nitrate.

[0006] Preferably, in step 1), the alkali in the alkaline solution includes calcium hydroxide or sodium hydroxide; the mass fraction of the alkali in the alkaline solution is 10~30%.

[0007] Preferably, in step 1), the liquid-solid mass ratio of the alkaline solution to the cesium garnet concentrate powder is 3~10:1; the alkaline leaching temperature is 80~150℃, and the time is 2~6h.

[0008] Preferably, in step 2), the acid includes dilute nitric acid; the mass concentration of the acid is 10-30%; and the mass ratio of the acid to the cesium-rich slag is 4-8:1.

[0009] Preferably, in step 2), the acid leaching temperature is 20~80℃ and the time is 3~5h.

[0010] Preferably, in step 3), the pH adjuster includes ammonia; the mass fraction of the ammonia is 20-40%. The aluminum deposition time is 1 to 3 hours.

[0011] Preferably, in step 4), the pressure of the negative pressure concentration is 0.1~0.7MPa and the temperature is 20~80℃.

[0012] Preferably, in step 4), the concentrate is cooled to 0~20°C.

[0013] Preferably, in step 5), the reagent used for recrystallization includes water; the number of recrystallizations is 2 to 3; and the solid-liquid mass ratio for each recrystallization is 1 to 5:1.

[0014] Preferably, in step 5), the drying temperature is 110~150℃ and the time is 4~8h.

[0015] This invention provides a method for preparing cesium nitrate by alkali dissolution of cesium garnet. The method involves mixing cesium garnet concentrate powder with an alkaline solution, followed by alkali leaching and filtration to obtain cesium-rich slag. The cesium-rich slag is then acidified and leached to obtain an acid leaching solution. The pH of the acid leaching solution is adjusted to remove Al. 3+ A cesium nitrate solution was obtained, which was then concentrated, cooled, and subjected to solid-liquid separation to obtain crude cesium nitrate. The crude cesium nitrate was recrystallized and dried to obtain the finished cesium nitrate. This invention utilizes an alkaline dissolution method to disrupt the structure of cesium garnet, causing it to form a cesium aluminum silicate precipitate, thus greatly enriching the cesium element. Acid leaching is then used to prepare the cesium nitrate product. This method directly generates cesium nitrate using acid after disrupting the cesium garnet structure, increasing the cesium recovery rate from 90% to over 95%. In contrast, the traditional sulfuric acid leaching method produces cesium vanadium precipitate, which easily precipitates and mixes with the cesium extraction residue, resulting in a low cesium recovery rate.

[0016] This invention enables full utilization of cesium resources in cesium garnet to obtain high-value cesium nitrate products. The resulting products have high purity, use readily available and simple raw materials, are relatively environmentally friendly, and have low operating costs, making them suitable for industrial production.

[0017] This invention uses cesium garnet to obtain a cesium nitrate solution through alkali dissolution, acid leaching, and aluminum precipitation. The cesium nitrate solution is then concentrated under negative pressure, cooled for crystallization, separated, recrystallized, and dried to obtain the finished cesium nitrate product. The main technical principles are as follows: Cs + +[AlO2] - +[SiO3] - →CsAlSiO4↓(1) CsAlSiO4+4HNO3→CsNO3+Al(NO3)3+H4SiO4↓ (2) Al(NO3)3+NH3·H2O→Al(OH)3↓+NH4NO3 (3) Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes alkali-dissolved cesium garnet to prepare cesium nitrate. Cesium garnet is a direct raw material for the production of cesium salts, with a wide market availability and readily available resources. Compared to the ion exchange method, this invention avoids complex processes, produces high-value cesium nitrate, and improves cesium utilization. The cesium recovery rate of this method reaches over 95%, reducing cesium resource loss and generating considerable economic benefits. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method for preparing cesium nitrate by alkali dissolution of cesium garnet according to the present invention. Detailed Implementation

[0019] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0020] like Figure 1 As shown, the present invention provides a method for preparing cesium nitrate by alkali dissolution of cesium garnet, comprising the following steps: 1) Mix cesium garnet concentrate powder with alkaline solution, perform alkaline leaching, and separate to obtain cesium-rich slag and recycled alkaline solution; 2) The cesium-rich slag is mixed with acid and subjected to acid leaching to obtain an acid leaching solution; 3) Add a pH adjuster to the acid leaching solution until the final pH value is 7.5~8.5, perform aluminum precipitation, and then filter under pressure to obtain a cesium nitrate solution; 4) The cesium nitrate solution is concentrated under negative pressure, and the resulting concentrate is cooled and crystallized, then separated to obtain crude cesium nitrate and concentrated mother liquor; 5) The crude cesium nitrate was recrystallized and dried sequentially to obtain cesium nitrate.

[0021] This invention does not impose any special limitations on the source and composition of the cesium garnet concentrate powder, which can be obtained in accordance with methods well known in the art. In the embodiments of this invention, the cesium garnet concentrate powder used has a Cs content of 20-25 wt% and a particle size of 200 mesh, and is derived from cesium-rich granite ore in Yashan, Yichun, Jiangxi Province.

[0022] In this invention, in step 1), the alkali in the alkaline solution preferably includes calcium hydroxide or sodium hydroxide; the solvent used in the alkaline solution is preferably water; the mass fraction of the alkali in the alkaline solution is preferably 10-30%, more preferably 15-25%, and even more preferably 20%.

[0023] In this invention, in step 1), the liquid-solid mass ratio of the alkaline solution to the cesium garnet concentrate is preferably 3~10:1, more preferably 5~9:1, and even more preferably 6~7:1; the alkaline leaching temperature is preferably 80~150℃, more preferably 100~130℃, and even more preferably 120℃; the leaching time is preferably 2~6h, more preferably 3~5h, and even more preferably 4h.

[0024] In this invention, the separation method described in step 1) is preferably filtration, and the resulting recycled alkaline solution can be reused as alkaline solution in the alkaline leaching step of cesium garnet concentrate powder.

[0025] The cesium-rich slag described in this invention contains >35 wt% cesium. The main component of the cesium-rich slag is cesium aluminosilicate.

[0026] In this invention, in step 2), the acid preferably includes dilute nitric acid; the mass concentration of the acid is preferably 10-30%, more preferably 15-20%; the mass ratio of the acid to the cesium-rich slag is preferably 4-8:1, more preferably 5-7:1, and even more preferably 6:1.

[0027] In this invention, in step 2), the acid leaching temperature is preferably 20~80℃, more preferably 30~60℃, even more preferably 40~50℃, and the time is preferably 3~5h, more preferably 4h.

[0028] After the acid leaching is completed, the resulting product is filtered under pressure to obtain an acid leaching solution and siliceous slag. The acid leaching solution mainly contains cesium nitrate, aluminum nitrate, and small amounts of lithium, sodium, potassium, calcium, and rubidium.

[0029] In this invention, in step 3), the pH adjuster preferably includes ammonia; the mass fraction of the ammonia is preferably 20-40%, more preferably 30%. This invention generates aluminum hydroxide precipitate by adjusting the pH.

[0030] In this invention, the aluminum deposition time is preferably 1 to 3 hours, more preferably 1 to 2 hours.

[0031] This invention precipitates Al by adding a pH adjuster until the final pH is 7.5-8.5 (more preferably 8.0). 3+ Then, the insoluble matter is removed by pressure filtration to obtain a cesium nitrate solution; the present invention does not have any special limitation on the pressure filtration, and can be carried out according to the process known in the art.

[0032] In this invention, in step 4), the pressure of the negative pressure concentration is preferably 0.1~0.7MPa, more preferably 0.3~0.6MPa, even more preferably 0.4~0.5MPa, and the temperature is preferably 20~80℃, more preferably 30~70℃, even more preferably 50~60℃.

[0033] The present invention does not have a special limitation on the cesium nitrate content in the concentrate obtained by negative pressure concentration; the corresponding concentrate can be obtained according to the above parameters.

[0034] After completing the negative pressure concentration, the present invention preferably cools the obtained concentrate, performs cooling crystallization, and then separates it; the cooling crystallization temperature is preferably 0~20℃, more preferably 5~15℃, and even more preferably 10℃; the separation method is preferably centrifugal separation. The present invention utilizes the solubility difference between cesium nitrate and ammonium nitrate to precipitate crude cesium nitrate through concentration and cooling crystallization.

[0035] The concentrated mother liquor obtained by negative pressure concentration of the present invention can be reused in the negative pressure concentration step of cesium garnet concentrate powder. When the concentrated mother liquor is reused in the negative pressure concentration of cesium garnet concentrate powder, the present invention preferably combines the crude cesium nitrate obtained from different processing stages and then recrystallizes it.

[0036] In this invention, in step 5), the reagent used for recrystallization preferably includes water, more preferably pure water; the number of recrystallizations is 2 to 3 times, more preferably 2 times; the solid-liquid mass ratio for each recrystallization is preferably 1 to 5:1, more preferably 2 to 3:1. This invention purifies nitric acid by recrystallization, utilizing the difference in solubility between nitric acid and other impurities.

[0037] In this invention, in step 5), the drying temperature is preferably 110~150℃, more preferably 120~130℃, and the drying time is preferably 4~8h, more preferably 5~6h.

[0038] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the reagents and raw materials described below are all commercially available.

[0040] In the following examples, the cesium garnet concentrate powder used was derived from the cesium-rich granite mine in Yashan, Yichun, Jiangxi Province.

[0041] Example 1

[0042] (1) Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to a 20% calcium hydroxide aqueous dispersion for alkali leaching. The liquid-solid mass ratio of the alkali solution to the cesium garnet concentrate powder was 5:1. The alkali leaching temperature was 120℃ and the leaching time was 4h. After filtration, cesium-rich slag (cesium content 38wt%) and recycled alkali solution were obtained. Acid leaching was carried out on the cesium-rich slag by adding 15wt% dilute nitric acid. The liquid-solid mass ratio of the acid to the cesium-rich slag was 6:1. The leaching temperature was 120℃ and the leaching time was 4h. The leaching temperature was 50℃, the leaching time was 4 hours, and the solution was filtered to obtain an acid leaching solution. 30wt% ammonia water was added to the acid leaching solution until the final pH value reached 8.0, and the reaction was carried out for 1 hour. The solution was then filtered to obtain a cesium nitrate solution. The cesium nitrate solution was then passed through a vacuum concentrator for negative pressure concentration at a pressure of 0.5 MPa and a concentration temperature of 60℃, resulting in a concentrated solution with a cesium nitrate content of 640 g / L. The concentrated solution was cooled to 0℃, crystallized, and then centrifuged to obtain crude cesium nitrate and a concentrated mother liquor. (2) Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to a 20% concentration calcium hydroxide aqueous dispersion and 20% of the recycled alkaline solution obtained in step (1) for alkaline leaching. The liquid-to-solid mass ratio of all alkaline solutions to cesium garnet concentrate powder was 5:1. The alkaline leaching temperature was 120℃ and the alkaline leaching time was 4h. After filtration, cesium-rich slag was obtained. Acid leaching was carried out on the cesium-rich slag with a concentration of 15wt% dilute nitric acid. The liquid-to-solid mass ratio of acid to cesium-rich slag was 6:1. The leaching temperature was 50℃. The reaction time was 4 hours, and the solution was filtered to obtain an acid leaching solution. Ammonia water with a concentration of 30 wt% was added to the acid leaching solution until the final pH value was 8.0. The solution was then reacted for 1 hour and filtered to obtain a cesium nitrate solution. The cesium nitrate solution was mixed with the concentrated mother liquor obtained in step (1) and then passed into a vacuum concentrator for negative pressure concentration. The concentration pressure was 0.5 MPa and the concentration temperature was 60 °C to obtain a concentrated solution with a cesium nitrate content of 640 g / L. The concentrated solution was cooled to 0 °C, crystallized, and then centrifuged to obtain crude cesium nitrate and concentrated mother liquor. (3) The crude cesium nitrate obtained in steps (1) and (2) is mixed with pure water at a solid-liquid mass ratio of 1:0.5 and recrystallized twice. The cesium nitrate crystals obtained by recrystallization are dried at a temperature of 120°C for 6 hours to obtain cesium nitrate.

[0043] In step (2), the alkaline solution obtained by filtration in step (1) is used in combination with the calcium hydroxide aqueous dispersion, which can save resources and reduce the waste of cesium ions and calcium hydroxide in the alkaline solution.

[0044] In step (2), the concentrated mother liquor obtained after solid-liquid separation in step (1) is mixed with the cesium nitrate solution for reuse, which can save resources and reduce the waste of cesium ions and ammonia in the cesium nitrate mother liquor.

[0045] Example 2

[0046] (1) Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to a 20% (w / w) calcium hydroxide aqueous dispersion for alkali leaching. The liquid-to-solid mass ratio was 7:1, the alkali leaching temperature was 120℃, and the alkali leaching time was 4h. After filtration, cesium-rich slag (cesium content 39wt%) was obtained. Acid leaching was carried out on the cesium-rich slag with 15wt% dilute nitric acid. The liquid-to-solid mass ratio was 6:1, the leaching temperature was 50℃, and the leaching time was 4h. h, filter under pressure to obtain an acid leaching solution; add 30wt% ammonia water to the acid leaching solution until the final pH reaches 8.0, react for 1 h, filter under pressure to obtain a cesium nitrate solution; pass the cesium nitrate solution into a vacuum concentrator for negative pressure concentration at a concentration pressure of 0.5 MPa and a concentration temperature of 60℃ to obtain a concentrated solution with a cesium nitrate content of 680 g / L; cool the concentrated solution to 10℃, crystallize, and centrifuge to obtain crude cesium nitrate and concentrated mother liquor; (2) Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to a 20% calcium hydroxide aqueous dispersion for alkaline leaching. The liquid-to-solid mass ratio was 7:1, the alkaline leaching temperature was 120℃, and the leaching time was 4h. After filtration, cesium-rich slag (cesium content 39wt%) was obtained. Acid leaching was carried out on the cesium-rich slag with 15wt% dilute nitric acid. The liquid-to-solid mass ratio was 6:1, the leaching temperature was 50℃, and the leaching time was 4h. After pressure filtration, acid leaching was obtained. ; Add 30wt% ammonia water to the acid leaching solution until the final pH value is 8.0, react for 1 hour, filter under pressure to obtain cesium nitrate solution; mix the cesium nitrate solution with the concentrated mother liquor obtained in step (1) and pass it into a vacuum concentrator for negative pressure concentration, the concentration pressure is 0.5MPa, the concentration temperature is 60℃, and a concentrated solution with a cesium nitrate content of 680g / L is obtained; cool the concentrated solution to 10℃, crystallize and centrifuge to obtain crude cesium nitrate and concentrated mother liquor; The crude cesium nitrate obtained in steps (1) and (2) was mixed with pure water at a mass ratio of 1:0.8 and recrystallized twice to obtain cesium nitrate crystals. The recrystallized cesium nitrate crystals were dried at 120℃ for 6 hours. The test results of the obtained products are shown in Table 1.

[0047] Example 3

[0048] (1) Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to a 20% calcium hydroxide aqueous dispersion for alkali leaching. The liquid-to-solid mass ratio was 9:1, the alkali leaching temperature was 120℃, and the leaching time was 4h. Cesium-rich slag (cesium content 38wt%) was obtained by filtration. Acid leaching was carried out on the cesium-rich slag with 15wt% dilute nitric acid. The liquid-to-solid mass ratio was 6:1, the leaching temperature was 50℃, and the leaching time was 4h. h, filter under pressure to obtain an acid leaching solution; add 30wt% ammonia water to the acid leaching solution until the final pH value is 8.0, react for 1 h, filter under pressure to obtain a cesium nitrate solution; pass the cesium nitrate solution into a vacuum concentrator for negative pressure concentration at a concentration pressure of 0.5 MPa and a concentration temperature of 60℃ to obtain a concentrated solution with a cesium nitrate content of 720 / L; cool the concentrated solution to 20℃, crystallize, and then centrifuge to obtain crude cesium nitrate and concentrated mother liquor; (2) Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to a 20% calcium hydroxide aqueous dispersion for alkali leaching. The liquid-to-solid mass ratio was 9:1, the alkali leaching temperature was 120℃, and the alkali leaching time was 4h. After filtration, cesium-rich slag (cesium content 38wt%) was obtained. Acid leaching was carried out on the cesium-rich slag with 15wt% dilute nitric acid. The liquid-to-solid mass ratio was 6:1, the leaching temperature was 50℃, and the leaching time was 4h. After pressure filtration, acid leaching was obtained. Immersion solution; Add 30wt% ammonia water to the acid leaching solution until the final pH value is 8.0, react for 1 hour, filter under pressure to obtain cesium nitrate solution; Mix the cesium nitrate solution with the concentrated mother liquor in step (1) and pass it into a vacuum concentrator for negative pressure concentration. The concentration pressure is 0.5MPa and the concentration temperature is 60℃ to obtain a concentrated solution with a cesium nitrate content of 720g / L; Cool the concentrated solution to 20℃, crystallize and centrifuge to obtain crude cesium nitrate and concentrated mother liquor; The crude cesium nitrate obtained in steps (1) and (2) was mixed with pure water at a mass ratio of 1:1 and recrystallized twice to obtain cesium nitrate crystals. The recrystallized cesium nitrate crystals were dried at 120℃ for 6 hours. The test results of the obtained products are shown in Table 1.

[0049] Comparative Example 1 (Acid Immersion Displacement Method)

[0050] Cesium garnet concentrate powder (200 mesh sieve, cesium grade 23.07%) was added to 40wt% sulfuric acid for acid leaching. The liquid-solid mass ratio was 4:1, the reaction temperature was 110℃, and the reaction time was 3h. After the reaction, the product was filtered at a constant temperature of 90℃ to obtain the acid leaching solution. The acid leaching solution was cooled to 20°C to precipitate cesium alum, and then centrifuged. The crude cesium alum product was added to pure water for two recrystallization processes, with a liquid-to-solid mass ratio of 5:1 for each recrystallization, to obtain refined cesium alum. The refined cesium alum was mixed with pure water at a solid-liquid mass ratio of 1:2 to form a slurry, and lime slurry was added to remove Al.3+ After the final pH reached 8.0, continue the reaction for 1 hour, then filter. Add calcium nitrate at a cesium to nitrate molar ratio of 1:1.05, stir for 30 min and filter to obtain crude cesium nitrate solution; add barium hydroxide octahydrate to crude cesium nitrate solution at a sulfate to barium molar ratio of 1:1.05, stir for 30 min and filter to obtain refined cesium nitrate solution; The refined cesium nitrate solution was evaporated and concentrated until crystals precipitated. The solution was then cooled to 0°C, centrifuged, and the resulting cesium nitrate crystals were dried at 120°C for 6 hours to obtain the cesium nitrate product.

[0051] The test results of the cesium nitrate products obtained in Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0052] Table 1. Test results of cesium nitrate products obtained in Examples 1-3 and Comparative Example 1

[0053] As shown in Table 1, the present invention successfully prepared cesium nitrate with a main content of over 99.9% by using the alkali-dissolving process of cesium garnet. Compared with the acid leaching method in Comparative Example 1, the cesium recovery rate was significantly improved.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing cesium nitrate by alkali dissolution of cesium garnet, characterized in that, Includes the following steps: 1) Mix cesium garnet concentrate powder with alkaline solution, perform alkaline leaching, and separate to obtain cesium-rich slag and recycled alkaline solution; 2) The cesium-rich slag is mixed with acid and subjected to acid leaching to obtain an acid leaching solution; 3) Add a pH adjuster to the acid leaching solution until the final pH value is 7.5~8.5, perform aluminum precipitation, and then filter under pressure to obtain a cesium nitrate solution; 4) The cesium nitrate solution is concentrated under negative pressure, and the resulting concentrate is cooled and crystallized, then separated to obtain crude cesium nitrate and concentrated mother liquor; 5) The crude cesium nitrate was recrystallized and dried sequentially to obtain cesium nitrate.

2. The method according to claim 1, characterized in that, In step 1), the alkali in the alkaline solution includes calcium hydroxide or sodium hydroxide; the mass fraction of the alkali in the alkaline solution is 10~30%.

3. The method according to claim 1 or 2, characterized in that, In step 1), the liquid-solid mass ratio of the alkaline solution to the cesium garnet concentrate powder is 3~10:1; the alkaline leaching temperature is 80~150℃ and the time is 2~6h.

4. The method according to claim 1, characterized in that, In step 2), the acid includes dilute nitric acid, and the mass concentration of the acid is 10-30%; the mass ratio of the acid to the cesium-rich slag is 4-8:

1.

5. The method according to claim 1 or 4, characterized in that, In step 2), the acid leaching temperature is 20~80℃ and the time is 3~5h.

6. The method according to claim 1, characterized in that, In step 3), the pH adjuster includes ammonia; the mass fraction of the ammonia is 20-40%. The aluminum deposition time is 1 to 3 hours.

7. The method according to claim 1, characterized in that, In step 4), the pressure of the negative pressure concentration is 0.1~0.7MPa and the temperature is 20~80℃.

8. The method according to claim 1, characterized in that, In step 4), the concentrate is cooled to 0~20℃.

9. The method according to claim 1, characterized in that, In step 5), the reagent used for recrystallization includes water; the recrystallization is performed 2 to 3 times; and the solid-liquid mass ratio for each recrystallization is 1 to 5:

1.

10. The method according to claim 1, characterized in that, In step 5), the drying temperature is 110~150℃ and the time is 4~8h.

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