Method for removing trace impurity elements from high-purity rubidium salt

Abstract

The invention provides a method for removing trace impurity elements from high-purity rubidium salt, which belongs to the technical field of metallurgy and comprises the following steps: dissolving the high-purity rubidium salt with deionized water to obtain a high-purity rubidium salt solution; adding a precipitator into the high-purity rubidium salt solution to carry out selective precipitation reaction of rubidium to obtain a rubidium-containing precipitation product, and preliminarily removing impurity elements such as sodium, potassium and cesium; the rubidium-containing precipitation product is filtered and then subjected to roasting treatment, the rubidium-containing precipitation product is subjected to a decomposition reaction, and a roasted product is obtained; an acidic transformation agent is added into the roasted product for a transformation reaction, and a rubidium salt solution is obtained; impurity elements such as sodium, potassium and cesium in the product are further removed through a recrystallization refining method, and the rubidium salt product with the purity reaching 99.9% or above is obtained. The method can effectively remove trace impurity elements in the high-purity rubidium salt, and has the advantages of short flow, few procedures and high product purity.

Description

Technical Field

[0001] The present invention belongs to the field of metallurgical technology, and particularly relates to a method for removing trace impurity elements from high-purity rubidium salts. Background Art

[0002] As an important rare alkali metal element, rubidium exhibits unique and indispensable application values in many high-tech fields. In the optoelectronic field, rubidium and its compounds can significantly improve the optical properties of special optical glasses, thus meeting the special requirements of high-precision optical instruments and optical communication devices. In the electronics industry, rubidium is widely used in the manufacture of high-performance electronic devices such as phototubes and photovoltaic cells. Its unique electron transition characteristics enable these devices to possess excellent properties such as high sensitivity and fast response, providing strong support for the development of electronic information technology. In the aerospace field, rubidium atomic clocks, with their ultra-high frequency stability and accuracy, have become the core components of time references in tasks such as satellite navigation and deep space exploration, playing a decisive role in ensuring the precise orbit control, communication synchronization, and accuracy of scientific data collection of spacecraft.

[0003] With the rapid development of modern technology, the purity requirements for rubidium salt materials in various fields are becoming increasingly stringent. Especially in some frontier fields such as quantum technology, hyperfine spectroscopy research, and high-end electronic chip manufacturing, even trace amounts of impurity elements may have a serious negative impact on the performance of rubidium materials, thereby restricting the breakthrough and application promotion of related technologies. Sodium, potassium, cesium, etc., as common impurity elements in rubidium salts, are extremely difficult to remove during the purification process of rubidium salts due to their similar chemical properties to rubidium. Therefore, developing an efficient, precise, and economically feasible method for removing trace impurity elements from high-purity rubidium salts has extremely important scientific significance and broad application prospects. It can not only fill the key technical gaps in the current rubidium salt purification technology field but also provide a solid material foundation guarantee for the upgrading and innovative development of related high-tech industries.

[0004] At present, a series of research works have been carried out on the methods for removing impurity elements from rubidium salts at home and abroad, mainly including the following common technical approaches:

[0005] (1) Stepwise crystallization method, that is, separating based on the differences in solubility of rubidium salts and impurity element salts under different conditions such as temperature and concentration. By controlling operations such as the temperature of the solution and the degree of evaporation and concentration, the impurity element salts are first crystallized out, while the rubidium salts remain in the solution.

[0006] Chinese Patent CN201510748140.1 discloses a process for continuously producing cesium rubidium alum and potassium alum. By subjecting a sulfate mother liquor containing cesium, rubidium, and potassium (Cs: 2.60 wt%, Rb: 0.08 wt%, K: 1.25 wt%) to vacuum cooling crystallization, a cesium rubidium alum crystal slurry is obtained. After multiple heat dissolutions, recrystallizations, and centrifugal separations, cesium rubidium alum products with a purity of ≥95% and potassium alum products with a purity of ≥97% can be obtained. The significant advantage of this method is that its principle is relatively simple and direct, without the need for complex equipment and special chemical reagents. However, due to the similar chemical properties of rubidium ions and potassium ions, the solubility curves of their salts are relatively similar, and only raw materials with a relatively high potassium content can be preliminarily purified. Moreover, the separation of rubidium / cesium has not been studied, making it difficult to meet the production requirements of high-purity rubidium salts.

[0007] (2) Ion exchange method, which is based on the principle of reversible exchange reaction between ion exchange resin and ions in solution to achieve the separation of impurity ions. The resin selectively adsorbs impurity ions while allowing rubidium ions to pass through, thereby achieving the separation purpose.

[0008] Chinese Patent CN201910266699.9 discloses a rubidium ion adsorption microsphere and its application. The rubidium ion adsorption microsphere prepared by using it can purify and refine an original solution with a rubidium ion concentration of 120 mg / L and an impurity ion concentration of 12 g / L to a rubidium ion concentration of 500 mg / L and an impurity ion concentration of 800 mg / L after one adsorption / desorption, with a significant separation effect. However, due to the non-absolutely specific selectivity of ion exchange resin, it is difficult to achieve efficient and thorough separation for impurities with chemical properties similar to rubidium. Multiple repeated exchange operations are often required, which not only increases the complexity of the process flow and the treatment cost but also easily leads to the loss of rubidium ions.

[0009] (3) Solvent extraction method, which utilizes the solubility difference of solutes in two immiscible solvents to achieve separation. By adjusting conditions such as the acidity of the solution, the concentration of the extractant, and the extraction time, rubidium ions are preferentially extracted into the organic phase, while potassium ions remain in the aqueous phase.

[0010] Chinese Patent CN202011120614.5 discloses a method for extracting rubidium chloride from high-salt brine containing rubidium. Using 4-tert-butyl-2-(α-methylbenzyl)phenol as the extractant and sulfonated kerosene as the diluent, the high-salt brine (Rb: 3.74 g / L, K: 142.42 g / L) is subjected to multi-stage extraction-washing-stripping treatment to obtain a stripping solution containing rubidium chloride. After precipitation, calcination, and recrystallization treatment, a rubidium chloride product with a purity of 99% is obtained. This method has high selectivity for rubidium ions, can effectively separate specific impurities, and can achieve good removal effects under suitable conditions. However, due to the complex extraction process, difficult to accurately control, it is easy to form emulsification, resulting in difficult phase separation, affecting the extraction effect and production efficiency.

[0011] In summary, the existing methods for removing trace impurity elements from rubidium salts all have their own defects and are difficult to meet the growing demand for high-purity rubidium salts in the current high-tech industry. Therefore, there is an urgent need to develop a new, more efficient and reliable method for removing trace impurity elements to promote the further development of rubidium salt purification technology. Summary of the Invention

[0012] Aiming at the problem that the existing technologies cannot efficiently remove trace impurity elements from high-purity rubidium salts, the present invention provides a method for removing trace impurity elements from high-purity rubidium salts, which can obtain a rubidium salt product with a purity of more than 99.9%.

[0013] To achieve the above object, the present invention adopts the following technical solutions:

[0014] A method for removing trace impurity elements from high-purity rubidium salts, comprising the following steps:

[0015] (1) Dissolve the high-purity rubidium salt in deionized water to obtain a high-purity rubidium salt solution;

[0016] (2) Add a precipitant to the high-purity rubidium salt solution for a selective precipitation reaction of rubidium to obtain a rubidium-containing precipitate product, and preliminarily remove the impurity elements sodium, potassium, and cesium;

[0017] (3) Filter the rubidium-containing precipitate product and then perform calcination treatment to cause a decomposition reaction to obtain a calcined product;

[0018] (4) Add an acidic transformation agent to the calcined product for a transformation reaction to obtain a rubidium salt solution;

[0019] (5) Further remove the impurity elements sodium, potassium, and cesium in the product by recrystallization refining method to obtain a rubidium salt product with a purity of more than 99.9%.

[0020] Further, the high-purity rubidium salt in step (1) is selected from one or more of rubidium sulfate, rubidium nitrate, rubidium carbonate, rubidium acetate, rubidium fluoride, rubidium chloride, rubidium bromide, rubidium iodide, and rubidium hydroxide.

[0021] Further, the total content of impurity elements sodium, potassium, and cesium in the high-purity rubidium salt in step (1) is 0.01-1%.

[0022] Further, the precipitant in step (2) is selected from one or more of oxalic acid, tartaric acid, ammonium oxalate, and ammonium tartrate. The rubidium ions in the solution react with the precipitant to be converted into a rubidium-containing precipitate product, which is separated from the sodium, potassium, and cesium ions in the solution. The main components of the rubidium-containing precipitate product are rubidium oxalate, rubidium tartrate, rubidium hydrogen ammonium oxalate, etc.

[0023] Further, the molar ratio of the precipitant to the high-purity rubidium salt in step (2) is 0.5:1-3:1. When the molar ratio of the precipitant to the rubidium salt is 2:1, theoretically all rubidium ions are converted into a precipitate. If the molar ratio of the precipitant to the rubidium salt > 2, that is, the addition amount of the precipitant is higher than the theoretical value, the precipitation reaction of rubidium ions can be more complete; if the molar ratio of the precipitant to the rubidium salt < 2, that is, the addition amount of the precipitant is lower than the theoretical value, only part of the rubidium ions in the solution can be converted into a precipitate.

[0024] Further, the temperature of the precipitation reaction in step (2) is 20-90 °C, and the reaction time is 20-120 min.

[0025] Further, the temperature of the roasting treatment in step (3) is 500-800 °C, and the time is 1-5 h. Through roasting, the rubidium compound in the rubidium-containing precipitate product is converted into rubidium carbonate. If the roasting temperature is higher than this range, it has no effect on the conversion reaction; if the roasting temperature is too low, the decomposition of the rubidium compound is incomplete and it cannot be completely converted into rubidium carbonate.

[0026] Further, the transformation agent in step (4) is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid. The acidic transformation agent reacts with rubidium carbonate in the roasting product to convert it into rubidium ions and enter the solution. The anions in the transformation agent are preferably the same as the anions in the high-purity rubidium salt, that is: if the high-purity rubidium salt is rubidium chloride, the transformation agent is selected as hydrochloric acid; if the high-purity rubidium salt is rubidium sulfate, the transformation agent is selected as sulfuric acid; if the high-purity rubidium salt is rubidium nitrate, the transformation agent is selected as nitric acid.

[0027] Further, the concentration of the transformation agent in step (4) is 0.5-4 mol / L.

[0028] Further, the pH value at the end point of the transformation reaction in step (4) is 2 - 3, and the reaction time is 0.5 - 2 h. If the pH value at the end point of the reaction is too low, the anion content in the solution will be too high, which may cause anion entrainment during crystallization and affect the crystallization purity; if the pH value at the end point of the reaction is too high, the transformation of rubidium carbonate will be incomplete, resulting in rubidium loss.

[0029] Further, the number of recrystallizations in step (5) is 0 - 2 times. The number of recrystallizations can be determined by the impurity content in the raw material high-purity rubidium salt. Each recrystallization can reduce the impurity content by about one order of magnitude.

[0030] The present invention has the following beneficial effects:

[0031] The present invention first dissolves high-purity rubidium salt in deionized water, adds a precipitant for precipitation, filters the precipitation product and then conducts a roasting treatment, then transforms the obtained roasting product with a transforming agent, and finally removes trace impurities in the product through a recrystallization refining method to obtain a rubidium salt product with a purity of over 99.9%. The present invention can effectively remove trace impurity elements in high-purity rubidium salt, has the advantages of short process flow, few processes, and high product purity, and is of great significance for promoting the development of rubidium salt purification technology in China and the development of high-tech industries using high-purity rubidium salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is a process flow chart for removing trace impurity elements from the high-purity rubidium salt described in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments.

[0035] The present invention discloses a method for removing trace impurity elements from high-purity rubidium salt, and its process flow chart is as Figure 1 shown. The method specifically includes steps such as dissolution, precipitation, roasting, transformation, recrystallization, etc., which will be described below with specific embodiments.

[0036] Example 1

[0037] Dissolve 100 g of rubidium chloride raw material (Na: 0.022%, K: 0.015%, Cs: 0.002%) in 200 mL of deionized water, add 1.25 times the theoretical amount of oxalic acid (the molar ratio of oxalic acid to rubidium chloride raw material is 2.5:1), precipitate at 80 °C for 2 h to obtain a precipitate product, and the precipitation rate of rubidium reaches 98.5%. Place the precipitate product in a muffle furnace and calcine at 700 °C for 3 h to obtain a calcined product. Use 4 mol / L transformation agent hydrochloric acid solution to transform the calcined product, control the solution pH = 2.5, time 1 h, and then evaporate and crystallize to obtain rubidium chloride product. After testing, the content of impurity element sodium is 0.0027%, the content of potassium is 0.0052%, and the content of the remaining impurities is lower than 0.001%, meeting the requirements of rubidium chloride product with a purity of 99.9%.

[0038] The main impurity contents of the rubidium chloride raw material and product in Example 1 are shown in Table 1 (mass fraction, ×10 -4 %):

[0039] Table 1

[0040]

[0041] Example 2

[0042] Dissolve 50 g of rubidium sulfate raw material (Na: 0.012%, K: 0.027%, Cs: 0.028%) in 150 mL of deionized water, add 1 times the theoretical amount of ammonium oxalate (the molar ratio of ammonium oxalate to rubidium sulfate raw material is 2:1), precipitate at 80 °C for 2 h to obtain a precipitate product, and the precipitation rate of rubidium reaches 92.3%. Place the precipitate product in a muffle furnace and calcine at 800 °C for 2 h to obtain a calcined product. Use 2 mol / L transformation agent sulfuric acid solution to transform the calcined product, control the solution pH = 2.8, time 2 h, and then evaporate and crystallize to obtain crude rubidium sulfate, and obtain rubidium sulfate product after 1 time of recrystallization. After testing, the content of impurity element potassium is 0.01%, the content of cesium is 0.0041%, and the content of the remaining impurities is lower than 0.001%, meeting the requirements of rubidium sulfate product with a purity of 99.9%.

[0043] The main impurity contents of the rubidium sulfate raw material and product in Example 2 are shown in Table 2 (mass fraction, ×10 -4 %):

[0044] Table 2

[0045]

[0046] Example 3

[0047] 500 g of rubidium nitrate raw material (Na: 0.930%, K: 0.180%, Cs: 0.023%) was dissolved in 1000 mL of deionized water. 1.2 times the theoretical amount of tartaric acid (the molar ratio of tartaric acid to rubidium nitrate raw material was 2.4:1) was added, and precipitation occurred at 80 °C for 2 h to obtain a precipitation product, with the precipitation rate of rubidium reaching 97.8%. The precipitation product was placed in a muffle furnace and calcined at 850 °C for 1 h to obtain a calcined product. The calcined product was transformed with 3 mol / L transformation agent nitric acid solution, controlling the solution pH = 3 and the time for 1 h. Subsequently, evaporation and crystallization were carried out to obtain crude rubidium nitrate, and the rubidium nitrate product was obtained through 2 recrystallizations. After detection, the contents of impurity elements potassium and sodium were 0.0046%, the content of cesium was 0.0019%, and the contents of other impurities were all lower than 0.001%, meeting the requirements of rubidium nitrate products with a purity of 99.9%.

[0048] Example 3 The main impurity contents of the rubidium nitrate raw material and the product are shown in Table 3 (mass fraction, ×10 -4 %).

[0049] Table 3

[0050]

[0051] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims described above.

Claims

1. A method for removing trace impurity elements from high-purity rubidium salts, characterized in that: The following steps are involved: (1) dissolving high-purity rubidium salt in deionized water to obtain a high-purity rubidium salt solution; (2) adding a precipitant to the high-purity rubidium salt solution to carry out a selective precipitation reaction of rubidium to obtain a rubidium-containing precipitate product, and preliminarily removing the impurity elements of sodium, potassium, and cesium; (3) filtering the rubidium-containing precipitate product and then calcining it to cause a decomposition reaction to obtain a calcined product; (4) adding an acidic transformation agent to the calcined product to carry out a transformation reaction to obtain a rubidium salt solution; (5) The impurity elements sodium, potassium and cesium in the product are further removed by recrystallization refining to obtain a rubidium salt product with a purity of more than 99.9%.

2. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The high-purity rubidium salt in step (1) is selected from one or more of rubidium sulfate, rubidium nitrate, rubidium carbonate, rubidium acetate, rubidium fluoride, rubidium chloride, rubidium bromide, rubidium iodide, and rubidium hydroxide.

3. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The content of impurity elements sodium, potassium and cesium in the high-purity rubidium salt in step (1) is 0.01-1% in total.

4. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The precipitant in step (2) is selected from one or more of oxalic acid, tartaric acid, ammonium oxalate and ammonium tartrate.

5. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The molar ratio of the precipitant to the high-purity rubidium salt in step (2) is 0.5:1-3:

1.

6. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The temperature of the precipitation reaction in step (2) is 20-90° C., and the reaction time is 20-120 min.

7. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The calcination temperature in step (3) is 500-800°C and the calcination time is 1-5 h.

8. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: In step (4), the transformation agent is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid, and the concentration of the transformation agent is 0.5-4 mol / L.

9. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The end point pH value of the transformation reaction in step (4) is 2-3, and the reaction time is 0.5-2 h.

10. The method for removing trace impurity elements from high-purity rubidium salt according to claim 1, characterized in that: The number of recrystallizations in step (5) is 0-2 times.

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