Method for preparing high-purity rubidium chloride from crude rubidium salt

Abstract

The application discloses a method for preparing high-purity rubidium chloride from rubidium coarse salt, which comprises the following steps: (1) obtaining an acid rubidium-containing solution from the rubidium coarse salt, adding a precipitant to obtain a precipitate; (2) dissolving the precipitate to obtain a complex salt solution containing rubidium; (3) recrystallizing to obtain a crystal; (4) washing the crystal to obtain a high-purity crystal; (5) adding the high-purity crystal into water to perform slurry preparation, and then adding ammonia water to react until the reaction is completed, so as to obtain a solution containing rubidium chloride; and (6) performing post-treatment on the solution containing rubidium chloride. The method for preparing high-purity rubidium chloride from rubidium coarse salt has the advantages that the purity of the final product can reach more than 99.99%, the technological process is simple, the production process is green and environment-friendly, the raw material consumption and production cost are low, and a feasible technical scheme is provided for large-scale industrial production of high-purity rubidium chloride.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubidium salt industry, and in particular to a preparation method of high-purity rubidium chloride with high product purity, high purification efficiency, simple process and low cost. BACKGROUND

[0002] With the rapid development of laser technology, quantum technology, hyperfine spectroscopy and high-end electronic chip manufacturing, the industry's requirements for the purity of rubidium chloride have been increased to more than 99.9%. However, alkali metal impurities such as sodium, potassium and cesium in rubidium salt are difficult to remove deeply due to their high similarity in chemical properties with rubidium, and trace impurities may affect the performance of materials, so it is urgent to develop innovative processes with high selectivity and industrial feasibility.

[0003] Regarding the preparation of rubidium chloride, in the existing public technology, solvent extraction, ion exchange and precipitation are the main means for purifying rubidium salt, but there are still problems such as insufficient product purity, low purification efficiency, complex process flow and high process cost. For example, Chinese patent application CN112194154A discloses a method for extracting rubidium and cesium from complex underground brine, which improves the purity of rubidium chloride to 99% by optimizing the extraction process, but it is difficult to meet the standard of more than 99.9% purity in the field of cutting-edge technology, and the product purity is insufficient. Chinese patent application CN120229747A discloses a method for removing trace impurity elements (such as sodium, potassium and cesium) from high-purity rubidium salt, which uses a selective precipitation method to shorten the process, and the purity of rubidium chloride reaches more than 99.9%, but the technical solution requires that the impurity content of the raw material be less than 1%, and the precipitant cannot be recycled, resulting in high production cost. Patent CN114350950A proposes a method for extracting rubidium and cesium from complex underground brine, and the purity of the final product of the brine treatment process is 99.5%, but the process is complex, the purification efficiency is low, and the process is difficult. Ultrasonic-assisted gradient crystallization can precisely control the nucleation / growth of crystals and reduce impurity entrainment, but it has not been applied to rubidium salt purification. SUMMARY

[0004] The present application provides a method for preparing high-purity rubidium chloride from crude rubidium salt to solve the technical problems mentioned in the background art.

[0005] To solve the above technical problems, the technical solution proposed by the present application is as follows:

[0006] A method for preparing high-purity rubidium chloride from crude rubidium salt, comprising the following steps:

[0007] (1) the rubidium coarse salt is dissolved in an acid solution to obtain an acidic rubidium-containing solution, a precipitant is added to the acidic rubidium-containing solution to obtain a rubidium-containing double salt precipitate; the hydrogen ion concentration in the acidic rubidium-containing solution is 3-6 mol / L, and the precipitant is a tin-containing precipitant, including at least one of tin tetrachloride, tin tetrachloride hydrate, tin chloride and tin chloride hydrate;

[0008] (2) the rubidium-containing double salt precipitate is heated to complete dissolution in an acid solution with a hydrogen ion concentration of 0.5-2 mol / L to obtain an acid solution containing a rubidium-containing double salt;

[0009] (3) the acid solution containing the rubidium-containing double salt is recrystallized to obtain a rubidium-containing double salt crystal;

[0010] (4) the rubidium-containing double salt crystal is washed with an acid solution with a hydrogen ion concentration of 4-6 mol / L to obtain a high-purity rubidium chlorostannate crystal;

[0011] (5) the washed high-purity rubidium chlorostannate crystal is added to water for slurry adjustment, and then ammonia water is added for reaction until complete to obtain a rubidium chloride-containing solution and a tin-containing precipitate;

[0012] (6) the rubidium chloride-containing solution is post-treated to obtain high-purity rubidium chloride.

[0013] The present application provides a feasible technical solution for large-scale industrial production of high-purity rubidium chloride by simplifying the process, first efficiently and low-costly converting rubidium in rubidium coarse salt into a rubidium-containing precipitate by a single precipitant, and then greatly improving the purity of the product by double salt recrystallization.

[0014] Based on the property that the solubility of rubidium chlorostannate in an acid solution decreases with increasing acidity, the present application forms a precipitate at high acidity to remove part of the impurities, and a large amount of impurities are entrained in the precipitate. Then the precipitate is heated and dissolved at low acidity, and after the impurities are left in the crystallization residue by cooling and crystallization, the impurities are washed and removed by a high-acidity solution to repeatedly reduce the impurity content.

[0015] As a further preferred embodiment of the above technical solution, the purity of the rubidium coarse salt is not less than 98%, and the main impurity elements are sodium, potassium and cesium, and the purity of the high-purity rubidium chloride obtained is not less than 99.9%. In order to obtain a product with a purity of more than 99.9%, the existing rubidium salt purification method generally requires the purity of the rubidium coarse salt to be more than 99% (i.e. only one order of magnitude of purity can be improved), and the present application can purify rubidium coarse salt with a purity of more than 97%, greatly reducing the production threshold and cost and improving the economic benefit.

[0016] The step (3) is re-crystallized by adding crystal seeds of high-purity rubidium chlorostannate to the acid solution containing the rubidium-containing double salt, and performing cooling crystallization under ultrasonic assistance to obtain a rubidium-containing double salt crystal. In the operation of re-crystallization, although the re-crystallization purification technology is often used in the preparation process of high-purity compounds, the traditional re-crystallization method has problems such as uneven crystal growth rate and serious impurity inclusion, so the operation of re-crystallization is further designed, the re-crystallization rate is ensured by adding crystal seeds and ultrasonic assistance, the re-crystallization effect is improved, and the product purity is further improved.

[0017] As a further preferred embodiment of the above technical solution, the molar amount of the crystal seeds added in step (3) is 0.1-1.0% of the total amount of rubidium ions in the acid solution containing the rubidium-containing double salt.

[0018] As a further preferred embodiment of the above technical solution, the temperature of the acid solution containing the rubidium-containing double salt is 80-95°C when the crystal seeds are added in step (3).

[0019] As a further preferred embodiment of the above technical solution, the cooling crystallization in step (3) adopts a multi-stage gradient cooling method, the terminal temperature of the cooling crystallization is 5-10°C, and the cooling crystallization is divided into 3-5 cooling stages, each cooling stage has a cooling amplitude of 20-40°C, and the total crystallization time of each cooling stage is 0.5-5h. By multi-stage gradient cooling and adjusting the cooling parameters, the re-crystallization rate and the crystal nucleation / growth effect can be accurately controlled, the impurity inclusion can be reduced, and the purity of the final product can be improved.

[0020] As a further preferred embodiment of the above technical solution, the cooling rate of each cooling stage in step (3) is 0.5-2°C / min. To ensure sufficient total crystallization time for each cooling stage, the holding crystallization time can be extended.

[0021] As a further preferred embodiment of the above technical solution, the ultrasonic power of the ultrasonic assistance treatment in step (3) is 100-500W, and the ultrasonic assistance treatment time in each cooling stage is 0.5-3.0h.

[0022] As a further preferred embodiment of the above technical solution, the ultrasonic assistance treatment in step (3) is performed in a continuous or intermittent manner.

[0023] As a further preferred embodiment of the above technical solution, the molar ratio of tin element in the precipitant to rubidium element in the acid solution containing rubidium is (0.5-3):1.

[0024] As a further preferred embodiment of the above technical solution, after the rubidium-containing double salt precipitate is obtained in step (1), the precipitate liquid is recycled multiple times for the precipitation of the acid solution containing rubidium in step (1).

[0025] As a further preferred embodiment of the above technical solution, in step (2), the heating temperature is 95-100°C.

[0026] As a further preferred embodiment of the above technical solution, the crystallization residue obtained in step (3) can be recycled to step (1) or step (2) for open circuit recovery treatment.

[0027] As a further preferred embodiment of the above technical solution, the washing times are 1-3 times.

[0028] As a further preferred embodiment of the above technical solution, the high-purity rubidium chlorostannate crystal obtained in step (4) is subjected to the operations of steps (2) to (4) repeatedly to improve the purity of the high-purity rubidium chlorostannate crystal.

[0029] As a further preferred embodiment of the above technical solution, the concentration of rubidium ions in the acidic rubidium-containing solution is 300-550 g / L; and the heating temperature in step (2) is 95-100℃.

[0030] As a further preferred embodiment of the above technical solution, in step (5), when the rubidium-containing double salt crystal is added into water for slurry preparation, the solid-liquid ratio is 1: (3-7), the ammonia water concentration is 25%-28%, and the pH during the reaction process is controlled at 7.0-8.5.

[0031] As a further preferred embodiment of the above technical solution, the tin-containing precipitate is recycled to step (1) as a precipitant.

[0032] As a further preferred embodiment of the above technical solution, in step (6), the post-treatment is evaporation roasting, the evaporation roasting temperature is 450-550℃, and the time is 1-5 h.

[0033] As a further preferred embodiment of the above technical solution, in step (4), the post-treatment further includes a recrystallization operation after evaporation roasting, the recrystallization times are 1-2 times, and the recrystallization times are determined by the cesium content in the raw rubidium coarse salt.

[0034] Based on the same technical concept, the application further provides a high-purity rubidium chloride prepared by the above method.

[0035] Based on the same technical concept, the application further provides an application of the high-purity rubidium chloride of the above technical solution, which is applied as a doping material in electronic chips or optoelectronic materials.

[0036] The application has the following beneficial effects:

[0037] The purity of the final product obtained by the method for preparing high-purity rubidium chloride from crude rubidium salt can reach more than 99.99%, the ultrasonic-assisted gradient cooling crystallization technology is first introduced for the preparation of high-purity rubidium salt, the ultrasonic cavitation effect inhibits local supersaturation, combined with gradient cooling to make the crystal grow in order, and reduce the impurity entrainment; in the production process, the use of organic solvents such as glacial acetic acid is completely avoided by simplifying the process flow, so that the production process is more green and environmentally friendly; a single precipitant system is used in the production process, and efficient recovery and recycling of the precipitant is realized, which greatly reduces the raw material consumption and production cost; not only the process flow is further shortened, and the purification efficiency is improved, but also breakthrough progress is made in the industrial implementation difficulty and production cost control, which provides a feasible technical scheme for large-scale industrial production of high-purity rubidium chloride.

[0038] The application will be further described in detail below with reference to the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The process flow chart of Example 1.

[0040] Figure 2 The process flow chart of Examples 2-6. DETAILED DESCRIPTION

[0041] The embodiments of the application will be described in detail below with reference to the accompanying drawings, but the application can be implemented in various different ways limited and covered by the claims.

[0042] Example 1:

[0043] The preparation method of high-purity rubidium chloride in this embodiment uses low-purity rubidium-containing raw materials, specifically 98% pure rubidium carbonate, and the main impurity content of the raw material is shown in Table 1 (mass fraction, %).

[0044] As shown in Figure 1 The preparation method of high-purity rubidium chloride in this embodiment includes the following steps:

[0045] (1) Dissolution: 2 kg of rubidium carbonate raw material is dissolved in 4 L of hydrochloric acid solution, and the hydrogen ion concentration in the acidic rubidium-containing solution is controlled to be 5.0 mol / L.

[0046] (2) Precipitation: 1.05 times the theoretical amount of tin tetrachloride pentahydrate (the molar ratio of tin to rubidium is 2.1:1) is added to the obtained acidic rubidium-containing solution, and after the stirring reaction is completed, a rubidium-containing double salt precipitate (rubidium chlorostannate) is obtained by filtration.

[0047] (3) Double salt recrystallization: the obtained rubidium-containing double salt precipitate is heated and dissolved in 1.0 mol / L hydrochloric acid solution, and once recrystallization is carried out by cooling, and the cooling endpoint is 10℃, and a rubidium-containing double salt crystal (rubidium chlorostannate crystal) is obtained by filtration.

[0048] (4) Washing: The rubidium-containing double salt crystal is washed twice with a hydrochloric acid solution having a hydrogen ion concentration of 5.0 mol / L.

[0049] (5) Double salt decomposition: The washed rubidium-containing double salt crystal is slurried with high-purity water at a solid-to-liquid ratio of 1:3, and then ammonia water is added to adjust the pH value to 7.5, to obtain a rubidium chloride solution (including a rubidium chloride solution and an ammonium chloride solution) and a tin-containing precipitate (tin hydroxide).

[0050] (6) Evaporation and calcination: The rubidium chloride solution is evaporated to dryness, and then calcined at 500°C for 2 h in a calcination furnace to obtain high-purity rubidium chloride with a purity of >99.93%, and the impurity content is shown in Table 2.

[0051] Example 2:

[0052] The preparation method of high-purity rubidium chloride in this example uses the same raw material as in Example 1, which is a low-purity rubidium-containing raw material, specifically rubidium carbonate with a purity of 98%, and the main impurity content of the raw material is shown in Table 1 (mass fraction, %).

[0053] As shown in Table 1, the preparation method of high-purity rubidium chloride in this example includes the following steps: Figure 2

[0054] (1) Dissolution: 2 kg of rubidium carbonate raw material is dissolved in 4 L of hydrochloric acid solution, and the hydrogen ion concentration of the acidic rubidium-containing solution is controlled at 5.0 mol / L.

[0055] (2) Precipitation: 1.05 times the theoretical amount of tin tetrachloride pentahydrate (molar ratio of tin to rubidium is 2.1:1) is added to the obtained acidic rubidium-containing solution, and after the reaction is completed, a rubidium-containing double salt precipitate (rubidium chlorostannate) is obtained by filtration.

[0056] (3) Dissolution: The obtained rubidium-containing double salt precipitate is heated to complete dissolution in 1.0 mol / L hydrochloric acid solution to obtain a clear solution, and the temperature is 100°C.

[0057] (4) Cooling and crystallization: The clear solution is cooled under ultrasonic assistance, and the cooling endpoint is 10°C. The power of ultrasonic treatment is 200 w, and the time is 2.0 h. High-purity rubidium chlorostannate seed crystals are added to the solution when the temperature is cooled to 95°C, and the molar addition amount of the seed crystals is 0.2% of the total amount of rubidium ions in the solution. A rubidium-containing double salt crystal (rubidium chlorostannate crystal) is obtained by filtration.

[0058] (5) Washing: The rubidium-containing double salt crystal is washed twice with a hydrochloric acid solution having a hydrogen ion concentration of 5.0 mol / L.

[0059] ​(6) Decomposition of double salt: the washed double salt containing rubidium was mixed with high-purity water at a solid-liquid ratio of 1:3, and then ammonia water was added to adjust the pH value to 7.5, and a solution containing rubidium chloride (including rubidium chloride solution and ammonium chloride solution) and a tin-containing precipitate (tin hydroxide) were obtained by filtration.

[0060] (7) Evaporation and calcination: the solution containing rubidium chloride was evaporated to dryness, and then was calcined in a calcination furnace at 500°C for 2h to obtain high-purity rubidium chloride with a purity of >99.97%, and the impurity content is shown in Table 2.

[0061] Comparing the production effects of Example 1 and Example 2, it is found that the crystallization rate is slow and the crystallization time is prolonged by not adding seed crystals and naturally cooling and crystallizing. In addition, the double salt crystals obtained without ultrasonic treatment are prone to clumping and wall sticking, resulting in a decrease in yield, and the content of impurities such as potassium and sodium is still high, making it difficult to obtain rubidium chloride products with a purity of >99.99%.

[0062] Example 3:

[0063] The preparation method of high-purity rubidium chloride in this example is consistent with that of Example 1, and the raw material is a low-purity rubidium-containing raw material, specifically rubidium carbonate with a purity of 98%. The main impurity content of the raw material is shown in Table 1 (mass fraction, %).

[0064] As shown in Figure 2 , the preparation method of high-purity rubidium chloride in this example includes the following steps:

[0065] (1) Dissolution: 2 kg of rubidium carbonate raw material was dissolved in 4 L of hydrochloric acid solution, and the hydrogen ion concentration in the acidic rubidium-containing solution was controlled at 6.0 mol / L.

[0066] (2) Precipitation: 1.05 times the theoretical amount of tin tetrachloride pentahydrate (molar ratio of tin to rubidium is 2.1:1) was added to the obtained acidic rubidium-containing solution, and after the stirring reaction was completed, a rubidium-containing double salt precipitate (rubidium chlorostannate) was obtained by filtration.

[0067] (3) Dissolution: the obtained rubidium-containing double salt precipitate was heated to complete dissolution in a 2.0 mol / L hydrochloric acid solution, and a clear solution was obtained, with a temperature of 100°C.

[0068] (4) Crystallization by cooling: the clear solution was cooled under ultrasonic assistance, and the final temperature was 10°C. The power of ultrasonic treatment was 300w, and the time was 2.0h. High-purity rubidium chlorostannate seed crystals were added to the solution when the temperature was cooled to 90°C, and the molar addition amount of the seed crystals was 0.8% of the total molar amount of rubidium ions in the solution. A rubidium-containing double salt crystal (rubidium chlorostannate crystal) was obtained by filtration.

[0069] (5) Washing: the rubidium-containing double salt crystal was washed twice with a hydrochloric acid solution with a hydrogen ion concentration of 6.0 mol / L.

[0070] (6) Double salt decomposition: the washed double salt containing rubidium was mixed with high-purity water to form a slurry with a solid-liquid ratio of 1:3, then ammonia water was added to adjust the pH value to 7.5, and a solution containing rubidium chloride (including rubidium chloride solution and ammonium chloride solution) and a tin-containing precipitate (tin hydroxide) were obtained by filtration.

[0071] (7) Evaporation and roasting: the solution containing rubidium chloride was evaporated to dryness and then roasted in a roasting furnace at 500°C for 2h to obtain high-purity rubidium chloride with a purity of >99.95%, and the impurity content is shown in Table 2.

[0072] Example 4:

[0073] The method for preparing high-purity rubidium chloride from rubidium coarse salt in this example has the same raw material as Example 1, which is a low-purity rubidium-containing raw material, specifically rubidium carbonate with a purity of 98%, and the main impurity content of the raw material is shown in Table 1 (mass fraction, %).

[0074] As shown in Figure 2 , the method for preparing high-purity rubidium chloride from rubidium coarse salt in this example includes the following steps:

[0075] (1) Dissolution: 2kg of rubidium carbonate raw material was dissolved in 4L of hydrochloric acid solution, and the hydrogen ion concentration in the acidic rubidium-containing solution was controlled at 5.0mol / L.

[0076] (2) Precipitation: 1.05 times the theoretical amount of tin tetrachloride pentahydrate (molar ratio of tin to rubidium is 2.1:1) was added to the obtained acidic rubidium-containing solution, and after the reaction was completed, the rubidium-containing double salt precipitate (rubidium chlorostannate) was obtained by filtration.

[0077] (3) Dissolution: the obtained rubidium-containing double salt was heated and dissolved in 1.0mol / L hydrochloric acid solution to obtain a clear solution, and the temperature was 100°C.

[0078] (4) Crystallization by cooling: first stage ultrasonic crystallization: the final cooling temperature was 80°C, the cooling rate was 2°C / min, the total crystallization time was 0.5h, high-purity rubidium chlorostannate seed crystals were added when the solution temperature was 95°C, the molar addition amount of the seed crystals was 0.2% of the total amount of rubidium ions in the solution, the ultrasonic treatment power was 200w, and continuous ultrasonic treatment was used, and the ultrasonic treatment time was 0.5h.

[0079] Second stage ultrasonic crystallization: the final cooling temperature was 50°C, the cooling rate was 1°C / min, the total crystallization time was 1.0h, the ultrasonic treatment power was 200w, and intermittent ultrasonic treatment was used, and the ultrasonic treatment time was 0.5h.

[0080] Third stage ultrasonic crystallization: the final cooling temperature was 10°C, the cooling rate was 0.5°C / min, the total crystallization time was 5.0h, the ultrasonic treatment power was 300w, and intermittent ultrasonic treatment was used, and the ultrasonic treatment time was 1.0h.

[0081] High-purity rubidium chlorostannate crystals are obtained after three-stage temperature reduction crystallization.

[0082] (5) Washing: the high-purity rubidium chlorostannate crystals are washed twice with a hydrochloric acid solution with a hydrogen ion concentration of 5 mol / L.

[0083] (6) Double salt decomposition: the washed high-purity rubidium chlorostannate crystals are slurried with high-purity water at a solid-liquid ratio of 1:3, then ammonia water is added to adjust the pH value to 7.5, and a rubidium chloride solution (including rubidium chloride solution and ammonium chloride solution) and tin-containing precipitate (tin hydroxide) are obtained by filtration.

[0084] (7) Evaporation and calcination: the rubidium chloride solution is evaporated to dryness and then calcined in a calcination furnace at 500°C for 2 h to obtain high-purity rubidium chloride with a purity of >99.99%, and the impurity content is shown in Table 2. Comparing the production effects of the present example and the previous examples, it can be seen that the product purity of the present example is further improved, because the gradient temperature reduction can better control the growth rate of the crystals, avoiding the entrainment of impurities during the crystal growth process caused by uncontrollable growth rate.

[0085] Example 5:

[0086] The method for preparing high-purity rubidium chloride from rubidium crude salt in the present example uses a low-purity rubidium-containing raw material, specifically 98% pure rubidium chloride, and the main impurity content of the raw material is shown in Table 1 (mass fraction, %).

[0087] As shown in Figure 2 , the method for preparing high-purity rubidium chloride from rubidium crude salt in the present example includes the following steps:

[0088] (1) Dissolution: 3 kg of rubidium chloride raw material is dissolved in 6 L of hydrochloric acid solution, and the hydrogen ion concentration in the acidic rubidium-containing solution is controlled at 5.5 mol / L.

[0089] (2) Precipitation: 1.1 times the theoretical amount of tin tetrachloride pentahydrate (molar ratio of tin to rubidium is 2.2:1) is added to the obtained acidic rubidium-containing solution, and after the stirring reaction is completed, a rubidium-containing double salt precipitate (rubidium chlorostannate) is obtained by filtration.

[0090] (3) Dissolution: the obtained rubidium-containing double salt is heated and dissolved in 1.2 mol / L hydrochloric acid solution, and the temperature of the clear solution is 100°C.

[0091] (4) Temperature reduction crystallization: first-stage ultrasonic crystallization: the final temperature of the temperature reduction is 80°C, the temperature reduction rate is 2°C / min, the total crystallization time is 0.5 h, high-purity rubidium chlorostannate seed crystals are added when the solution temperature is 98°C, the seed crystal addition amount is 0.1% of the total amount of rubidium ions in the solution, the ultrasonic treatment power is 300 w, and continuous ultrasonic treatment is performed for 0.5 h.

[0092] Second ultrasonic crystallization: the final temperature of cooling is 60℃, the cooling rate is 1℃ / min, the total crystallization time is 1.0h, the ultrasonic treatment power is 200w, and the intermittent ultrasonic treatment is performed for 0.5h.

[0093] Third ultrasonic crystallization: the final temperature of cooling is 40℃, the cooling rate is 0.5℃ / min, the total crystallization time is 1.0h, the ultrasonic treatment power is 200w, and the intermittent ultrasonic treatment is performed for 0.5h.

[0094] Fourth ultrasonic crystallization: the final temperature of cooling is 10℃, the cooling rate is 1.0℃ / min, the total crystallization time is 3.0h, the ultrasonic treatment power is 500w, and the intermittent ultrasonic treatment is performed for 0.5h.

[0095] High-purity rubidium chlorostannate crystals are obtained after four-stage cooling crystallization.

[0096] (5) Washing: the high-purity rubidium chlorostannate crystals are washed once with a hydrochloric acid solution with a hydrogen ion concentration of 4mol / L.

[0097] (6) Double salt decomposition: the washed high-purity rubidium chlorostannate crystals are slurried with high-purity water at a solid-liquid ratio of 1:3, then ammonia water is added to adjust the pH value to 8.0, and a rubidium chloride solution (including a rubidium chloride solution and an ammonium chloride solution) and a tin-containing precipitate are obtained by filtration.

[0098] (7) Evaporation and calcination: the obtained rubidium chloride solution is evaporated to dryness, and then high-purity rubidium chloride with a purity of >99.99% is obtained by calcining at 500℃ for 3.5h in a calcination furnace, and the impurity content is shown in Table 2.

[0099] Example 6:

[0100] The method for preparing high-purity rubidium chloride from rubidium crude salt in this example uses a low-purity rubidium-containing raw material, specifically, rubidium sulfate with a purity of 97%, and the main impurity content of the raw material is shown in Table 1 (mass fraction, %).

[0101] As shown in Figure 2 , the method for preparing high-purity rubidium chloride from rubidium crude salt in this example includes the following steps:

[0102] (1) Dissolution: 5kg of rubidium sulfate raw material is dissolved in 10L of hydrochloric acid solution, and the hydrogen ion concentration of the acidic rubidium-containing solution is controlled to be 5.0mol / L.

[0103] (2) Precipitation: 1.15 times the theoretical amount of tin tetrachloride pentahydrate (the molar ratio of tin to rubidium is 2.3:1) is added to the obtained acidic rubidium-containing solution, and after the stirring reaction is completed, a rubidium-containing double salt precipitate (rubidium chlorostannate) is obtained by filtration.

[0104] (3) Dissolution: the obtained rubidium-containing double salt was heated and dissolved in 0.8 mol / L hydrochloric acid solution, and the temperature of the clear solution was 100°C.

[0105] (4) Cooling and crystallization: first-stage ultrasonic crystallization: the final temperature of cooling was 60°C, the cooling rate was 2°C / min, the total crystallization time was 0.5 h, and high-purity rubidium chlorostannate seed crystals were added when the solution temperature was 98°C, the amount of seed crystals was 0.4% of the total amount of rubidium ions in the solution, the ultrasonic treatment power was 500 W, and continuous ultrasonic treatment was performed for 0.5 h.

[0106] Second-stage ultrasonic crystallization: the final temperature of cooling was 30°C, the cooling rate was 1°C / min, the total crystallization time was 1.0 h, the ultrasonic treatment power was 200 W, and intermittent ultrasonic treatment was performed for 0.5 h.

[0107] Third-stage ultrasonic crystallization: the final temperature of cooling was 10°C, the cooling rate was 0.5°C / min, the total crystallization time was 3.0 h, the ultrasonic treatment power was 200 W, and intermittent ultrasonic treatment was performed for 1.0 h.

[0108] High-purity rubidium chlorostannate crystals were obtained after three-stage cooling and crystallization.

[0109] (5) Washing: the high-purity rubidium chlorostannate crystals were washed twice with 5 mol / L hydrochloric acid solution.

[0110] (6) The high-purity rubidium chlorostannate crystals after washing were returned to step (3), and steps (3) to (5) were repeated once to obtain high-purity rubidium chlorostannate crystals.

[0111] (7) Double salt decomposition: the high-purity rubidium chlorostannate crystals were slurried with high-purity water at a solid-to-liquid ratio of 1:3, then ammonia water was added to adjust the pH value to 7.5, and a rubidium chloride-containing solution (including rubidium chloride solution and ammonium chloride solution) and tin-containing precipitate were obtained by filtration.

[0112] (8) Evaporation and calcination: the obtained rubidium chloride-containing solution was evaporated to dryness, and then calcined in a calcination furnace at 500°C for 2.5 h to obtain high-purity rubidium chloride.

[0113] (9) Recrystallization: the obtained rubidium chloride was dissolved in water for 1 time of recrystallization to obtain high-purity rubidium chloride with a purity of >99.99%, and the impurity content is shown in Table 2.

[0114] Comparative Example 1:

[0115] The raw material used in this comparative example was rubidium carbonate with a purity of 99%, which was the same as in Example 1, and the main impurity content of the raw material was as shown in Table 1 (mass fraction, %).

[0116] The preparation method of rubidium chloride in this comparative example included the following steps:

[0117] (1) Dissolution: 2 kg of rubidium carbonate raw material was dissolved in hydrochloric acid solution to obtain a nearly neutral rubidium chloride solution.

[0118] (2) Recrystallization: Without the step of double salt precipitation, one recrystallization operation was directly performed to obtain a rubidium chloride product, and the purity was still 99.70%, and the impurity content was shown in Table 2. The results showed that only the cesium impurity was reduced, and the remaining impurities had no obvious removal effect.

[0119] Comparative Example 2:

[0120] The raw material of this comparative example was rubidium chloride with a purity of 98%, and the main impurity content of the raw material was the same as that of Example 5, as shown in Table 1 (mass fraction, %).

[0121] The preparation method of rubidium chloride of this comparative example included the following steps:

[0122] (1) Dissolution: 3 kg of rubidium chloride raw material was dissolved in 6 L of hydrochloric acid solution, and the hydrogen ion concentration in the acidic rubidium-containing solution was controlled at 5.5 mol / L.

[0123] (2) Precipitation: 1.1 times the theoretical amount of tin tetrachloride pentahydrate (molar ratio of tin to rubidium was 2.2:1) was added to the obtained acidic rubidium-containing solution, and after the stirring reaction was completed, a rubidium-containing double salt precipitate was obtained by filtration.

[0124] (3) Double salt decomposition: Without the steps of double salt dissolution and crystallization, the obtained rubidium-containing double salt precipitate was added to high-purity water to make a slurry with a solid-liquid ratio of 1:3, then ammonia water was added to adjust the pH value to 8.0, and a rubidium-containing solution and a tin-containing precipitate were obtained by filtration.

[0125] (4) Evaporation and calcination: the obtained rubidium-containing solution was evaporated to dryness, and then calcined at 500°C for 3.5 h in a calcination furnace to obtain rubidium chloride.

[0126] (5) Recrystallization: the obtained rubidium chloride after calcination was dissolved in water for one recrystallization refining to obtain rubidium chloride with a purity of >99.67%, and the impurity content was shown in Table 2. The results showed that the purity of rubidium chloride obtained without the steps of double salt dissolution and crystallization was significantly reduced, and the content of impurities such as potassium was still high, making it difficult to obtain a rubidium chloride product with higher purity.

[0127] Comparative Example 3:

[0128] The preparation method of rubidium chloride from crude rubidium salt of this comparative example was the same as that of Example 1, and the raw material was a low-purity rubidium-containing raw material, and the main impurity content of the raw material was shown in Table 1 (mass fraction, %).

[0129] The preparation method of rubidium chloride from crude rubidium salt of this comparative example included the following steps:

[0130] (1) Dissolution: 2 kg of rubidium carbonate raw material was dissolved in 4 L of hydrochloric acid solution, and the hydrogen ion concentration in the acidic rubidium-containing solution was controlled to be 2.0 mol / L.

[0131] (2) Precipitation: 1.05 times the theoretical amount of tin tetrachloride pentahydrate (molar ratio of tin to rubidium is 2.1:1) was added to the obtained acidic rubidium-containing solution, and after the stirring reaction was completed, a rubidium-containing double salt precipitate (rubidium chlorostannate) was obtained by filtration.

[0132] (3) Dissolution: The obtained rubidium-containing double salt was heated and dissolved in 4 mol / L hydrochloric acid solution, and once recrystallization was performed by cooling, and the cooling endpoint was 10°C. A rubidium-containing double salt crystal (rubidium chlorostannate crystal) was obtained by filtration.

[0133] (4) Washing: 2 mol / L hydrochloric acid solution was used for washing twice.

[0134] (5) Double salt decomposition: The obtained rubidium-containing double salt crystal was slurried with high-purity water at a solid-to-liquid ratio of 1:3, and then ammonia water was added to adjust the pH value to 7.5. A rubidium chloride-containing solution (including rubidium chloride solution and ammonium chloride solution) and a tin-containing precipitate were obtained by filtration.

[0135] (6) Evaporation and calcination: The obtained rubidium chloride-containing solution was evaporated to dryness, and then high-purity rubidium chloride was obtained by calcining at 500°C for 2 h in a calcination furnace.

[0136] (7) Recrystallization: Since the raw material of the present comparative example still contains a small amount of cesium impurities, the obtained rubidium chloride was dissolved in water for once recrystallization purification, and rubidium chloride with a purity of >99.9% was obtained, and the impurity content is shown in Table 2. By analyzing the results of Example 1 and the present comparative example, it can be seen that the control of the acidity of the acid solution in different steps can improve the purity of the final product.

[0137] Table 1: Raw material types, purity and main impurity content (% by mass) in each example and comparative example

[0138] Table 2: Product purity and main impurity content (% by mass) in each example and comparative example

[0139] The above is only a preferred embodiment of the present application, and the protection scope of the present application is not limited to the above examples. Improvements and changes obtained by those skilled in the art without departing from the technical concept of the present application should also be considered within the protection scope of the present application.

[0140] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that variations, modifications, substitutions and changes can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A method for preparing high-purity rubidium chloride from crude rubidium salt, characterized in that, Includes the following steps: (1) Dissolve crude rubidium salt in an acidic solution to obtain an acidic rubidium-containing solution, add a precipitant to the acidic rubidium-containing solution to obtain a rubidium-containing double salt precipitate; the hydrogen ion concentration in the acidic rubidium-containing solution is 3~6 mol / L, and the precipitant is a tin-containing precipitant, including at least one of tin tetrachloride, tin tetrachloride hydrate, tin chloride and tin chloride hydrate; (2) The rubidium-containing complex salt precipitate is heated in an acid solution with a hydrogen ion concentration of 0.5~2 mol / L until it is completely dissolved to obtain an acid solution containing the rubidium complex salt; (3) The acid solution containing the rubidium double salt is recrystallized to obtain rubidium double salt crystals; (4) The rubidium-containing double salt crystals were washed with an acid solution with a hydrogen ion concentration of 4~6 mol / L to obtain high-purity rubidium chlorostannate crystals; (5) Add the washed high-purity rubidium chloride crystals to water to make a slurry, then add ammonia water to react until complete, to obtain a rubidium chloride solution and a tin precipitate; (6) The rubidium chloride solution is post-treated to obtain high-purity rubidium chloride; the post-treatment is an evaporation-calcination and recrystallization operation performed sequentially, the evaporation-calcination temperature is 450~550℃, the time is 1~5h, and the recrystallization is performed 1~2 times.

2. The method for preparing high-purity rubidium chloride from crude rubidium salt according to claim 1, characterized in that, The purity of the crude rubidium salt is not less than 97%, and the main impurity elements are sodium, potassium and cesium. The purity of the high-purity rubidium chloride prepared is not less than 99.9%.

3. The method for preparing high-purity rubidium chloride from crude rubidium salt according to claim 1, characterized in that, In step (1), the molar ratio of tin in the precipitant to rubidium in the acidic rubidium-containing solution is (0.5~3):

1.

4. The method for preparing high-purity rubidium chloride from crude rubidium salt according to claim 1, characterized in that, Before recrystallization in step (3), high-purity rubidium chlorostannate seed crystals are added to the acid solution containing rubidium complex salt. Under ultrasonic assistance, cooling crystallization is carried out to obtain rubidium complex salt crystals.

5. The method for preparing high-purity rubidium chloride from crude rubidium salt according to claim 4, characterized in that, The molar amount of the seed crystal is 0.1 to 1.0% of the total molar amount of rubidium ions in the acid solution containing the rubidium complex salt; when the seed crystal is added, the temperature of the acid solution containing the rubidium complex salt is 80 to 95°C.

6. The method for preparing high-purity rubidium chloride from crude rubidium salt according to claim 4, characterized in that, The cooling crystallization described in step (3) adopts a multi-stage gradient cooling method. The final temperature of cooling crystallization is 5~10℃, divided into 3~5 cooling stages, with a cooling range of 20~40℃ for each stage. The total crystallization time for a single cooling stage is 0.5~5h, and the cooling rate of each cooling stage is 0.5~2℃ / min.

7. The method for preparing high-purity rubidium chloride from crude rubidium salt according to claim 6, characterized in that, In step (3), the ultrasonic power of the ultrasonic-assisted treatment is 100~500W, and the ultrasonic-assisted treatment time in a single cooling stage is 0.5~3.0h; the ultrasonic-assisted treatment is carried out continuously or intermittently.

8. The method for preparing high-purity rubidium chloride from crude rubidium salt according to any one of claims 1-7, characterized in that, After obtaining the rubidium-containing double salt precipitate in step (1), the remaining liquid of the precipitate is repeatedly reused in step (1) for open-circuit recovery treatment of the acidic rubidium-containing solution after precipitation; the remaining liquid after recrystallization in step (3) is reused in step (2); the tin-containing precipitate obtained in step (5) is reused as a precipitant in step (1).

9. The method for preparing high-purity rubidium chloride from crude rubidium salt according to any one of claims 1-7, characterized in that, The concentration of rubidium ions in the acidic rubidium-containing solution in step (1) is 300~550 g / L; the heating temperature in step (2) is 95~100℃.

10. The method for preparing high-purity rubidium chloride from crude rubidium salt according to any one of claims 1-7, characterized in that, Repeat steps (2) to (4) to improve the purity of the high-purity rubidium chlorostannate crystals obtained in step (4).

11. The method for preparing high-purity rubidium chloride from crude rubidium salt according to any one of claims 1-7, characterized in that, In step (5), when the rubidium-containing double salt crystals are added to water for slurry preparation, the solid-liquid ratio is 1:(3~7), the ammonia concentration is 25%~28%, and the pH is controlled at 7.0~8.5 during the reaction.

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