A method for separating rubidium and cesium from lithium extraction tail liquid using bromophenol extractants

Abstract

The present application provides a method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, and belongs to the technical field of hydrometallurgy. The method comprises the following steps: mixing styrene and bromophenol, adding a catalyst to react, and obtaining a bromophenol extractant; mixing the bromophenol extractant and a diluent to obtain an organic phase; adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium and cesium to 12-14, using the organic phase to perform multi-stage countercurrent extraction of cesium, and obtaining a cesium-rich organic phase and a potassium-rich rubidium raffinate; washing and stripping the cesium-rich organic phase in sequence to obtain a cesium-rich solution; adjusting the pH of the potassium-rubidium raffinate to 12-14, using the organic phase to perform multi-stage countercurrent extraction of rubidium, and obtaining a rubidium-rich organic phase and a potassium-rich raffinate, and recovering the potassium-rich raffinate; washing and stripping the rubidium-rich organic phase in sequence to obtain a rubidium-rich solution. The method of the present application can improve the selectivity for rubidium and cesium and enhance the ability to separate and purify rubidium and cesium.

Description

Technical Field

[0001] The present application belongs to the technical field of hydrometallurgy, and specifically relates to a method for separating rubidium and cesium from lithium extraction tail liquid by using a bromophenol extractant. Background Art

[0002] With the rapid development of the new energy industry, the demand for lithium resources continues to increase. At the same time, lithium extraction from lepidolite to prepare lithium carbonate has become one of the mainstream processes. The mother liquor after lithium extraction from lepidolite contains rich elements such as rubidium (Rb), cesium (Cs), potassium (K), and sodium (Na). In view of the excellent photoelectric properties and electrical conductivity of alkali metals rubidium and cesium, they have broad application prospects in many high-tech fields. Therefore, the recovery of precious metals such as rubidium and cesium from lithium extraction tail liquor has important economic value and social significance.

[0003] At present, the laboratory preparation methods of rubidium, cesium and their compounds at home and abroad have developed from the initial step-by-step crystallization separation method to the current ion exchange method, solvent extraction method, precipitation method and other methods for separating and purifying rubidium and cesium from mineral resources and waste liquids. Among these methods, solvent extraction is favored because of its efficient separation ability and high selectivity. Commonly used extractants include crown ethers, phenol alcohols, dibitramine and its derivatives. Among them, phenol alcohols and crown ether extractants are the most widely used, and the most used phenol alcohol extractant is 4-tert-butyl-2-(α-methylbenzyl)phenol (t-BAMBP). As a weakly acidic substituted phenol, t-BAMBP shows high extraction efficiency and selectivity in phenol alcohol extractants.

[0004] Although these extractants have improved the separation effect of rubidium and cesium to a certain extent, since rubidium, cesium and potassium belong to the same main group elements, they have very similar physical and chemical properties, which leads to the problem of low separation selectivity in the separation and purification process. In addition, as dispersed elements, rubidium and cesium usually coexist with other metal elements such as potassium in nature, which further increases the difficulty of separation and purification. Although the existing extraction technology can achieve the separation of rubidium and cesium to a certain extent, it still has deficiencies in separation efficiency and selectivity in complex systems, especially when dealing with complex systems such as lithium extraction tail liquid, the limitations of the existing technology are particularly prominent.

[0005] Therefore, there is an urgent need to develop a new extraction method that can improve the selectivity for rubidium and cesium and enhance the ability to separate and purify rubidium and cesium. Summary of the invention

[0006] In view of this, the present application provides a method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, which can improve the selectivity for rubidium and cesium and enhance the ability to separate and purify rubidium and cesium.

[0007] In a first aspect, the present application provides a method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, comprising the following steps:

[0008] Step S1, mixing styrene and brominated phenol, adding a catalyst to react, and preparing a brominated phenol extractant;

[0009] Step S2, mixing the brominated phenol extractant and a diluent to obtain an organic phase;

[0010] Step S3, adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium and cesium to 12-14, using the organic phase to perform multi-stage countercurrent extraction of cesium to obtain a cesium-rich organic phase and a potassium-rubidium-rich raffinate; washing and stripping the cesium-rich organic phase in sequence to obtain a cesium-rich solution;

[0011] Step S4, adjusting the pH of the potassium-rubidium-rich raffinate to 12-14, using the organic phase to perform multi-stage countercurrent extraction of rubidium to obtain a rubidium-rich organic phase and a potassium-rich raffinate, and recovering the potassium-rich raffinate; washing and stripping the rubidium-rich organic phase in sequence to obtain a rubidium-rich solution.

[0012] By adopting the above technical scheme, the method of separating rubidium and cesium from lithium extraction tail liquid using bromophenol extractants proposed in this application improves the selectivity for rubidium and cesium, and enhances the separation and purification ability of rubidium and cesium. This application uses styrene and bromophenol as raw materials to synthesize a new type of bromophenol extractant. Compared with traditional phenol extractants, the para-alkyl chain of the phenolic hydroxyl group is replaced by electron-withdrawing bromine, which reduces the steric hindrance and makes it easier for rubidium and cesium ions to combine with the extractant. In addition, bromine atoms, as electron-withdrawing groups, can enhance the polarity of the extractant molecules, thereby enhancing the electrostatic attraction between the rubidium and cesium ions, greatly improving the separation and purification ability of rubidium and cesium.

[0013] The present application step S1 synthesizes a bromophenol extractant with high selectivity, providing an effective reagent for the subsequent separation step. Step S2 mixes the bromophenol extractant with a diluent to prepare an organic phase, which is convenient for subsequent extraction operations. Step S3 adjusts the pH value and uses the organic phase for multi-stage countercurrent extraction. Since the stability of the organic extractant of cesium is higher than that of rubidium, cesium preferentially forms a stable complex with the extractant in the organic phase and is transferred to the organic phase. After multi-stage countercurrent extraction, the separation efficiency is improved, and the efficient separation of cesium is achieved. Step S4 adjusts the pH value and uses the organic phase for multi-stage countercurrent extraction. Since the stability of the organic extractant of rubidium is higher than that of potassium, rubidium preferentially forms a stable complex with the extractant in the organic phase and is transferred to the organic phase, achieving the efficient separation of rubidium.

[0014] The present application utilizes bromophenol extractants to more effectively separate rubidium and cesium from complex lithium extraction tail liquid, thereby improving separation efficiency. The present application also utilizes a multi-stage countercurrent extraction, washing and stripping process, which is simple and easy to implement and industrially applicable. Furthermore, the extractant can be recycled, which reduces chemical consumption and waste generation, and reduces the impact on the environment.

[0015] Optionally, in step S1, the molar ratio of the styrene to the brominated phenol is 1:1-3:1; the brominated phenol includes at least one of 4-bromophenol and tribromophenol; the catalyst is concentrated phosphoric acid, and the mass concentration of phosphoric acid in the concentrated phosphoric acid is greater than or equal to 85%; the reaction temperature is 80-160°C, and the reaction time is 2-4h.

[0016] By adopting the above technical scheme, the styrene and brominated phenol of the present application adopt a specific molar ratio, which can ensure the completeness of the reaction, avoid the waste of raw materials, and ensure that the final synthesized brominated phenol extractant has the expected selectivity and purity, thereby improving the extraction efficiency of rubidium and cesium.

[0017] The specific reaction temperature and reaction time of styrene and bromophenol in the present application can ensure the reaction activity while avoiding the occurrence of side reactions or the destruction of the product structure.

[0018] Optionally, in step S2, the diluent is selected from at least one of n-octane, diethylbenzene, sulfonated kerosene, D80 solvent oil, and petroleum ether; and the volume ratio of the brominated phenol extractant to the diluent is 0.5:1~1:1.

[0019] By adopting the above technical solution, the diluent of the present application can dissolve the bromophenol extractant well, ensure the uniform distribution of the extractant in the organic phase, thereby improving the extraction efficiency. In addition, these diluents are relatively stable during the extraction process, are not prone to chemical reactions, and can ensure the activity of the extractant.

[0020] The volume ratio of the brominated phenol extractant and the diluent of the present application can ensure the stability of the organic phase and the effective use of the extractant during the extraction process, thereby improving the separation efficiency of rubidium and cesium.

[0021] Optionally, in step S3, the extraction stage number of the multi-stage countercurrent extraction of cesium is 5 to 11, the two-phase contact time is 5 to 12 min, the extraction temperature is 16 to 35° C., and the phase ratio is 1:8 to 8:1.

[0022] By adopting the above technical solution, step S3 of the present application can contact the aqueous phase and the organic phase multiple times through multi-stage countercurrent, thereby increasing the chance of cesium ions transferring from the aqueous phase to the organic phase. As the number of stages increases, the cesium separation effect is better. The two-phase contact time of the present application determines the time for cesium ions to contact with the extractant. A sufficiently long contact time can ensure that cesium has enough time to form a stable complex, while not excessively extending the treatment cycle, thereby improving the separation efficiency.

[0023] Optionally, in step S3, the washing of the cesium-rich organic phase is a multi-stage countercurrent washing, the number of washing stages is 2 to 6, the two-phase contact time is 3 to 9 minutes, the washing temperature is 20 to 40° C., and the phase ratio is 1:5 to 5:1.

[0024] By adopting the above technical solution, the multi-stage countercurrent washing in step S3 of the present application can effectively remove impurities that may be introduced during the extraction process, ensuring that the final cesium-rich solution has a high purity.

[0025] Optionally, in step S3, the stripping of the cesium-rich organic phase is multi-stage countercurrent stripping, the stripping stage is 3 to 7, the two-phase contact time is 3 to 9 minutes, the washing temperature is 20 to 40° C., and the phase ratio is 1:4 to 4:1.

[0026] By adopting the above technical solution, the multi-stage countercurrent stripping in step S3 of the present application can more thoroughly transfer cesium from the organic phase to the aqueous phase, ensure that the cesium in the organic phase is effectively desorbed, and enhance the overall effect of cesium separation and purification.

[0027] Optionally, in step S4, the extraction stage number of the multi-stage countercurrent extraction of rubidium is 5 to 11, the two-phase contact time is 5 to 12 min, the extraction temperature is 16 to 35° C., and the phase ratio is 1:8 to 8:1.

[0028] By adopting the above technical solution, the multi-stage countercurrent extraction in step S4 of the present application can ensure the efficient separation of rubidium ions, improve the selectivity of rubidium, and enhance the separation and purification capacity of rubidium.

[0029] Optionally, in step S4, the washing of the rubidium-rich organic phase is a multi-stage countercurrent washing, the number of washing stages is 2 to 6, the two-phase contact time is 3 to 9 minutes, the washing temperature is 20 to 40° C., and the phase ratio is 1:5 to 5:1;

[0030] The stripping of the rubidium-rich organic phase is multi-stage countercurrent stripping, the stripping stages are 3 to 7, the contact time between the two phases is 3 to 9 minutes, the washing temperature is 20 to 40°C, and the phase ratio is 1:4 to 4:1.

[0031] By adopting the above technical solution, the multi-stage countercurrent washing in step S4 of the present application can more thoroughly remove impurities that may be introduced during the extraction process. At the same time, the specific washing temperature can both ensure the migration speed of impurities and maintain the stability of the system. The multi-stage countercurrent stripping in step S4 of the present application can ensure that rubidium has enough opportunities to be desorbed, thereby improving the stripping efficiency.

[0032] Optionally, the washing in step S3 and step S4 is pure water washing;

[0033] The stripping agent used for the stripping in step S3 and step S4 is independently selected from at least one of sulfuric acid, hydrochloric acid and nitric acid; the concentration of the stripping agent is 0.1-5 mol / L.

[0034] By adopting the above technical solution, the present application uses pure water washing to effectively remove impurities that may exist in the organic phase without introducing new impurities, thereby ensuring the purity of the final product. The stripping agent and its concentration range of the present application can adapt to different desorption requirements, ensuring the desorption effect while reducing unnecessary resource consumption.

[0035] Optionally, the cesium extraction rate is ≥90%, and the rubidium extraction rate is ≥48%.

[0036] By adopting the above technical scheme, the method of separating rubidium and cesium from lithium extraction tail liquid using bromophenol extractants in the present application can effectively improve the selectivity of rubidium and cesium, enhance the separation and purification capacity of rubidium and cesium, so that the cesium extraction rate is ≥90% and the rubidium extraction rate is ≥48%.

[0037] In summary, the present invention includes at least one of the following beneficial technical effects:

[0038] 1. This application uses styrene and brominated phenol as raw materials to synthesize a new type of brominated phenol extractant. Compared with traditional phenol extractants, the para-alkyl chain of the phenolic hydroxyl group is replaced by electron-withdrawing bromine, which reduces the steric hindrance and makes it easier for rubidium and cesium ions to combine with the extractant, greatly improving the separation efficiency of rubidium and cesium.

[0039] 2. This application adopts a multi-stage countercurrent extraction, washing and stripping process, which is simple and easy to implement and industrially applicable. In addition, the extractant can be recycled, which reduces chemical consumption and waste generation, and reduces the impact on the environment. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0041] The inventors of the present application found in the separation study of rubidium and cesium that rubidium, cesium and potassium have very similar physical and chemical properties, so that in the separation and purification process, the separation selectivity of rubidium and cesium is low. In addition, rubidium and cesium, as dispersed elements, usually coexist with other metal elements such as potassium in nature, further increasing the difficulty of separation and purification. Although the existing extraction technology can achieve the separation of rubidium and cesium to a certain extent, when dealing with complex systems such as lithium extraction tail liquid, there is a problem of low separation selectivity of rubidium and cesium and poor separation and purification ability.

[0042] In order to solve the above problems, the present application proposes a method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, comprising the following steps:

[0043] Step S1, mixing styrene and brominated phenol, adding a catalyst to react, and preparing a brominated phenol extractant;

[0044] Step S2, mixing the brominated phenol extractant and a diluent to obtain an organic phase;

[0045] Step S3, adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium and cesium to 12-14, using the organic phase to perform multi-stage countercurrent extraction of cesium to obtain a cesium-rich organic phase and a potassium-rubidium-rich raffinate; washing and stripping the cesium-rich organic phase in sequence to obtain a cesium-rich solution;

[0046] Step S4, adjusting the pH of the potassium-rubidium-rich raffinate to 12-14, using the organic phase to perform multi-stage countercurrent extraction of rubidium to obtain a rubidium-rich organic phase and a potassium-rich raffinate, and recovering the potassium-rich raffinate; washing and stripping the rubidium-rich organic phase in sequence to obtain a rubidium-rich solution.

[0047] The scheme of the present application is described below in conjunction with the following specific examples. Unless otherwise specified, the raw materials used in the following examples are all from common commercial products, and the devices or equipment used are all purchased from conventional market sales channels. Specific embodiments

[0049] Example 1

[0050] This embodiment provides a method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, comprising the following steps:

[0051] Step S1, mixing styrene and bromophenol, adding concentrated phosphoric acid, mixing and reacting at 80° C. for 3 hours to obtain a bromophenol extractant; wherein the molar ratio of styrene to bromophenol is 1:1, the bromophenol used is 4-bromophenol; and the mass concentration of the concentrated phosphoric acid is 98%;

[0052] Step S2, mixing a bromophenol extractant and a diluent to obtain an organic phase; wherein the diluent is n-octane, and the volume ratio of the bromophenol extractant to the diluent is 0.5:1;

[0053] Step S3, adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium to 12, using the organic phase to perform multi-stage countercurrent extraction of cesium, the extraction stage is 5, the two-phase contact time is 5min, the extraction temperature is 16°C, and the phase ratio is 1:8, to obtain a cesium-rich organic phase and a potassium-rubidium-rich raffinate, detecting the concentration of cesium in the potassium-rubidium-rich raffinate, and performing multi-stage countercurrent washing on the cesium-rich organic phase, the washing stage is 2, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:5, followed by multi-stage countercurrent stripping, the stripping stage is 3, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:4, to obtain a cesium-rich solution;

[0054] Step S4, adjusting the pH of the potassium-rubidium-rich raffinate to 12, using the organic phase for multi-stage countercurrent extraction of rubidium, the extraction stage is 5, the two-phase contact time is 5min, the extraction temperature is 16°C, and the phase ratio is 1:8, to obtain a rubidium-rich organic phase and a potassium-rich raffinate, detecting the concentration of rubidium in the potassium-rich raffinate and recovering the potassium-rich raffinate; performing multi-stage countercurrent washing on the rubidium-rich organic phase, the washing stage is 2, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:5, followed by multi-stage countercurrent stripping, the stripping stage is 3, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:4, to obtain a rubidium-rich solution;

[0055] Wherein, the washing in step S3 and step S4 is pure water washing, the stripping agent used for stripping is sulfuric acid, and the concentration of the stripping agent is 0.1 mol / L.

[0056] Example 2

[0057] This embodiment provides a method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, comprising the following steps:

[0058] Step S1, mixing styrene and bromophenol, adding concentrated phosphoric acid, mixing and reacting at 80° C. for 3 hours to obtain a bromophenol extractant; wherein the molar ratio of styrene to bromophenol is 1:1, the bromophenol used is 4-bromophenol; and the mass concentration of the concentrated phosphoric acid is 98%;

[0059] Step S2, mixing a bromophenol extractant and a diluent to obtain an organic phase; wherein the diluent is n-octane, and the volume ratio of the bromophenol extractant to the diluent is 0.5:1;

[0060] Step S3, adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium and cesium to 14, using the organic phase to perform multi-stage countercurrent extraction of cesium, the extraction stage is 5, the two-phase contact time is 5min, the extraction temperature is 16°C, and the phase ratio is 1:8, to obtain a cesium-rich organic phase and a potassium-rubidium-rich raffinate, detecting the concentration of cesium in the potassium-rubidium-rich raffinate, and performing multi-stage countercurrent washing on the cesium-rich organic phase, the washing stage is 2, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:5, followed by multi-stage countercurrent stripping, the stripping stage is 3, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:4, to obtain a cesium-rich solution;

[0061] Step S4, adjusting the pH of the potassium-rubidium-rich raffinate to 14, using the organic phase to perform multi-stage countercurrent extraction of rubidium, the extraction stage is 5 stages, the two-phase contact time is 5 minutes, the extraction temperature is 16°C, and the phase ratio is 1:8, to obtain a rubidium-rich organic phase and a potassium-rich raffinate, detecting the concentration of rubidium in the potassium-rich raffinate and recovering the potassium-rich raffinate; performing multi-stage countercurrent washing on the rubidium-rich organic phase, the washing stage is 2 stages, the two-phase contact time is 3 minutes, the washing temperature is 20°C, and the phase ratio is 1:5, followed by multi-stage countercurrent stripping, the stripping stage is 3 stages, the two-phase contact time is 3 minutes, the washing temperature is 20°C, and the phase ratio is 1:4, to obtain a rubidium-rich solution;

[0062] Wherein, the washing in step S3 and step S4 is pure water washing, the stripping agent used for stripping is sulfuric acid, and the concentration of the stripping agent is 0.1 mol / L.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 2 is that the conventional phenolic extractant 4-tert-butyl-2-(α-methylbenzyl)phenol (t-BAMBP) is used in Comparative Example 1, and the specific steps are as follows:

[0065] Step S1, mixing t-BAMBP and a diluent to obtain an organic phase; wherein the diluent is n-octane, and the volume ratio of t-BAMBP to the diluent is 0.5:1;

[0066] Step S2, adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium to 14, using the organic phase to perform multi-stage countercurrent extraction of cesium, the extraction stage is 5, the two-phase contact time is 5min, the extraction temperature is 16°C, and the phase ratio is 1:8, to obtain a cesium-rich organic phase and a potassium-rubidium-rich raffinate, detecting the concentration of cesium in the potassium-rubidium-rich raffinate, and performing multi-stage countercurrent washing on the cesium-rich organic phase, the washing stage is 2, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:5, followed by multi-stage countercurrent stripping, the stripping stage is 3, the two-phase contact time is 3min, the washing temperature is 20°C, and the phase ratio is 1:4, to obtain a cesium-rich solution;

[0067] Step S3, adjusting the pH of the potassium-rubidium-rich raffinate to 14, using the organic phase to perform multi-stage countercurrent extraction of rubidium, the extraction stage is 5 stages, the two-phase contact time is 5 minutes, the extraction temperature is 16°C, and the phase ratio is 1:8, to obtain a rubidium-rich organic phase and a potassium-rich raffinate, detecting the concentration of rubidium in the potassium-rich raffinate and recovering the potassium-rich raffinate; performing multi-stage countercurrent washing on the rubidium-rich organic phase, the washing stage is 2 stages, the two-phase contact time is 3 minutes, the washing temperature is 20°C, and the phase ratio is 1:5, followed by multi-stage countercurrent stripping, the stripping stage is 3 stages, the two-phase contact time is 3 minutes, the washing temperature is 20°C, and the phase ratio is 1:4, to obtain a rubidium-rich solution;

[0068] Wherein, the washing in step S2 and step S3 is pure water washing, the stripping agent used for stripping is sulfuric acid, and the concentration of the stripping agent is 0.1 mol / L.

[0069] Experimental testing

[0070] Cesium extraction rate = [1-(cesium concentration in potassium-rubidium-rich raffinate / cesium initial concentration)] × 100%;

[0071] Rubidium extraction rate = [1-(rubidium concentration in potassium-rich raffinate / initial rubidium concentration)] × 100%.

[0072] The methods for separating rubidium and cesium from lithium extraction tail liquor of Examples 1-2 and Comparative Example 1 were tested for initial cesium concentration, cesium concentration in potassium-rich rubidium raffinate, cesium extraction rate, initial rubidium concentration, rubidium concentration in potassium-rich raffinate, and rubidium extraction rate. The test results are shown in Table 1.

[0073] Table 1

[0074]

[0075] From the test results in Table 1, it can be seen that the method of separating rubidium and cesium from lithium extraction tail liquid using bromophenol extractants in Examples 1 and 2 has high selectivity for rubidium and cesium, strong separation and purification ability of rubidium and cesium, cesium extraction rate ≥90%, and rubidium extraction rate ≥48%.

[0076] In Comparative Example 1, the traditional phenol extractant 4-tert-butyl-2-(α-methylbenzyl)phenol (t-BAMBP) was used to separate and purify rubidium and cesium. The extraction rates of rubidium and cesium were significantly reduced. The rubidium and cesium separation and purification capabilities of the traditional phenol extractant were inferior to those of the bromophenol extractant of the present application.

[0077] Embodiments 3 to 16

[0078] Example 3

[0079] The difference between Example 3 and Example 2 is that in step S1 of Example 3, the molar ratio of styrene to bromophenol is 2:1.

[0080] Example 4

[0081] The difference between Example 4 and Example 2 is that in step S1 of Example 4, the molar ratio of styrene to bromophenol is 3:1.

[0082] Example 5

[0083] The difference between Example 5 and Example 3 is that in step S2 of Example 5, the volume ratio of the bromophenol extractant to the diluent is 0.8:1.

[0084] Example 6

[0085] The difference between Example 6 and Example 3 is that in step S2 of Example 6, the volume ratio of the bromophenol extractant to the diluent is 1:1.

[0086] Example 7

[0087] The difference between Example 7 and Example 5 is that in step S3 of Example 7, the extraction stage number of the multi-stage countercurrent extraction of cesium is 8, the two-phase contact time is 9 minutes, the extraction temperature is 25° C., and the phase ratio is 1:1.

[0088] Example 8

[0089] The difference between Example 8 and Example 5 is that in step S3 of Example 8, the extraction stage number of the multi-stage countercurrent extraction of cesium is 11, the two-phase contact time is 12 min, the extraction temperature is 35° C., and the phase ratio is 8:1.

[0090] Example 9

[0091] The difference between Example 9 and Example 7 is that in step S3 of Example 9, the number of washing stages of the multi-stage countercurrent washing is 4, the two-phase contact time is 6 minutes, the washing temperature is 30° C., and the phase ratio is 1:1;

[0092] The number of stripping stages of the multi-stage countercurrent stripping is 5, the contact time between the two phases is 6 minutes, the washing temperature is 30°C, and the phase ratio is 1:1.

[0093] Example 10

[0094] The difference between Example 10 and Example 7 is that in step S3 of Example 10, the number of washing stages of the multi-stage countercurrent washing is 6, the two-phase contact time is 9 minutes, the washing temperature is 40° C., and the phase ratio is 5:1;

[0095] The number of stripping stages of the multi-stage countercurrent stripping is 7, the contact time between the two phases is 9 minutes, the washing temperature is 40°C, and the phase ratio is 4:1.

[0096] Embodiment 11

[0097] The difference between Example 11 and Example 9 is that in step S4 of Example 11, the extraction stage number of multi-stage countercurrent extraction of rubidium is 8 stages, the two-phase contact time is 8 minutes, the extraction temperature is 35° C., and the phase ratio is 1:1.

[0098] Example 12

[0099] The difference between Example 12 and Example 9 is that in step S4 of Example 12, the extraction stage number of multi-stage countercurrent extraction of rubidium is 11 stages, the two-phase contact time is 12 minutes, the extraction temperature is 35° C., and the phase ratio is 8:1.

[0100] Embodiment 13

[0101] The difference between Example 13 and Example 11 is that in step S4 of Example 13, the number of washing stages of the multi-stage countercurrent washing is 4, the two-phase contact time is 6 minutes, the washing temperature is 30° C., and the phase ratio is 1:1;

[0102] The number of stripping stages of the multi-stage countercurrent stripping is 5, the contact time between the two phases is 6 minutes, the washing temperature is 30°C, and the phase ratio is 1:1.

[0103] Embodiment 14

[0104] The difference between Example 14 and Example 11 is that in step S4 of Example 14, the number of washing stages of the multi-stage countercurrent washing is 6, the two-phase contact time is 9 minutes, the washing temperature is 40° C., and the phase ratio is 5:1;

[0105] The number of stripping stages of the multi-stage countercurrent stripping is 7, the contact time between the two phases is 9 minutes, the washing temperature is 40°C, and the phase ratio is 4:1.

[0106] Embodiment 15

[0107] The difference between Example 15 and Example 13 is that the concentration of the stripping agent used for stripping in step S3 and step S4 of Example 15 is 2.5 mol / L.

[0108] Example 16

[0109] The difference between Example 16 and Example 13 is that the concentration of the stripping agent used for stripping in step S3 and step S4 of Example 16 is 5 mol / L.

[0110] The methods for separating rubidium and cesium from lithium extraction tail liquor of Examples 3 to 16 were tested for initial cesium concentration, cesium concentration in potassium-rich rubidium raffinate, cesium extraction rate, initial rubidium concentration, rubidium concentration in potassium-rich raffinate, and rubidium extraction rate. The test results are shown in Table 2.

[0111] Table 2

[0112]

[0113] From the test results in Table 2, it can be seen that the difference between Example 3 and Example 4 and Example 2 is that the molar ratio of styrene to bromophenol is different, among which the rubidium extraction rate and cesium extraction rate obtained by separating and purifying rubidium and cesium in Example 3 are the highest. The molar ratio of styrene to bromophenol in Example 3 can ensure that the reaction is completely carried out, and ensure that the finally synthesized bromophenol extractant has a high selectivity, thereby improving the extraction rate of rubidium and cesium.

[0114] The difference between Example 5 and Example 6 and Example 3 is that the volume ratio of the bromophenol extractant to the diluent is different, wherein the cesium extraction rate and the rubidium extraction rate of Example 5 are the highest. The volume ratio of the bromophenol extractant to the diluent in Example 5 can ensure the stability of the organic phase and the effective use of the extractant during the extraction process, thereby improving the separation efficiency of rubidium and cesium.

[0115] The difference between Example 7 and Example 8 and Example 5 is that in step S3, the parameters such as the extraction stage and the two-phase contact time of the multi-stage countercurrent extraction of cesium are different, wherein the cesium extraction rates of Example 7 and Example 8 are similar and higher than that of Example 5. Example 7 ensures the separation efficiency of cesium without excessively extending the processing cycle.

[0116] The difference between Example 9 and Example 10 and Example 7 is that in step S3, the number of washing stages and the two-phase contact time of the multi-stage countercurrent washing, the number of stripping stages and the two-phase contact time of the multi-stage countercurrent stripping are different, wherein the cesium extraction rates of Example 9 and Example 10 are similar and higher than that of Example 7. Example 9 not only ensures the separation efficiency of cesium, but also takes into account the simplicity of operation.

[0117] The difference between Example 11 and Example 12 and Example 9 is that in step S4, the parameters such as the extraction stage and the two-phase contact time of the multi-stage countercurrent extraction of rubidium are different. Among them, the rubidium extraction rates of Example 11 and Example 12 are similar and higher than that of Example 9.

[0118] The difference between Example 13 and Example 14 and Example 11 is that in step S4, the parameters such as the number of washing stages and the contact time of two phases in the multi-stage countercurrent washing, the number of stripping stages and the contact time of two phases in the multi-stage countercurrent stripping are different. Among them, the rubidium extraction rates of Example 13 and Example 14 are similar and higher than that of Example 11.

[0119] The difference between Example 15 and Example 16 and Example 13 is that the concentrations of the stripping agents used in step S3 and step S4 are different. In particular, Example 15 reduces unnecessary resource consumption while ensuring the desorption effect.

[0120] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant, characterized in that: The following steps are involved: Step S1, mixing styrene and brominated phenol, adding a catalyst to react, and preparing a brominated phenol extractant; Step S2, mixing the brominated phenol extractant and a diluent to obtain an organic phase; Step S3, adjusting the pH of the alkali metal lithium extraction tail liquid containing rubidium and cesium to 12-14, using the organic phase to perform multi-stage countercurrent extraction of cesium to obtain a cesium-rich organic phase and a potassium-rubidium-rich raffinate; washing and stripping the cesium-rich organic phase in sequence to obtain a cesium-rich solution; Step S4, adjusting the pH of the potassium-rubidium-rich raffinate to 12-14, using the organic phase to perform multi-stage countercurrent extraction of rubidium to obtain a rubidium-rich organic phase and a potassium-rich raffinate, and recovering the potassium-rich raffinate; washing and stripping the rubidium-rich organic phase in sequence to obtain a rubidium-rich solution.

2. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In the step S1, the molar ratio of the styrene to the brominated phenol is 1:1 to 3:1; The brominated phenol includes at least one of 4-bromophenol and tribromophenol; The catalyst is concentrated phosphoric acid, and the mass concentration of phosphoric acid in the concentrated phosphoric acid is greater than or equal to 85%; The reaction temperature is 80-160° C. and the reaction time is 2-4 hours.

3. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In the step S2, the diluent is selected from at least one of n-octane, diethylbenzene, sulfonated kerosene, D80 solvent oil, and petroleum ether; and the volume ratio of the brominated phenol extractant to the diluent is 0.5:1 to 1:

1.

4. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In the step S3, the extraction stage number of the multi-stage countercurrent extraction of cesium is 5 to 11, the two-phase contact time is 5 to 12 minutes, the extraction temperature is 16 to 35° C., and the phase ratio is 1:8 to 8:

1.

5. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In step S3, the washing of the cesium-rich organic phase is a multi-stage countercurrent washing, the washing stages are 2 to 6, the two-phase contact time is 3 to 9 minutes, the washing temperature is 20 to 40° C., and the phase ratio is 1:5 to 5:

1.

6. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In the step S3, the stripping of the cesium-rich organic phase is multi-stage countercurrent stripping, the stripping stage is 3 to 7, the contact time between the two phases is 3 to 9 minutes, the washing temperature is 20 to 40° C., and the phase ratio is 1:4 to 4:

1.

7. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In the step S4, the extraction stage of the multi-stage countercurrent extraction of rubidium is 5 to 11, the two-phase contact time is 5 to 12 minutes, the extraction temperature is 16 to 35° C., and the phase ratio is 1:8 to 8:

1.

8. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: In the step S4, the washing of the rubidium-rich organic phase is a multi-stage countercurrent washing, the washing stages are 2 to 6, the two-phase contact time is 3 to 9 minutes, the washing temperature is 20 to 40° C., and the phase ratio is 1:5 to 5:1; The stripping of the rubidium-rich organic phase is multi-stage countercurrent stripping, the stripping stages are 3 to 7, the contact time between the two phases is 3 to 9 minutes, the washing temperature is 20 to 40°C, and the phase ratio is 1:4 to 4:

1.

9. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: The washing in step S3 and step S4 is pure water washing; The stripping agent used for the stripping in step S3 and step S4 is independently selected from at least one of sulfuric acid, hydrochloric acid and nitric acid; the concentration of the stripping agent is 0.1-5 mol / L.

10. The method for separating rubidium and cesium from lithium extraction tail liquid using a bromophenol extractant according to claim 1, characterized in that: The cesium extraction rate is ≥90%, and the rubidium extraction rate is ≥48%.

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