Method for separating potassium, rubidium and cesium in lithium precipitation mother liquor through extraction-electrochemistry combination

Abstract

The invention discloses a method for separating potassium, rubidium and cesium in lithium precipitation mother liquor through extraction-electrochemistry combination, which comprises the following steps of: firstly, pretreating the lithium precipitation mother liquor, adjusting the pH value of the lithium precipitation mother liquor to be alkaline, and adding a potassium stabilizer to be complexed with potassium ions in the lithium precipitation mother liquor to obtain a solution A; performing cesium extraction on the solution A to obtain a cesium-extracted organic phase and raffinate containing potassium and rubidium; performing electrochemical adsorption by taking the raffinate containing potassium and rubidium as an electrolyte and taking a rubidium ion selective electrode active material as a working electrode to obtain a rubidium-containing adsorption sample and a potassium-containing complex after-adsorption solution; finally, the rubidium-containing adsorption sample is desorbed, and the cesium-extracted organic phase is subjected to reverse extraction, so that effective separation of the rubidium-containing adsorption sample, the cesium-extracted organic phase and the cesium The separation method disclosed by the invention can effectively improve the separation efficiency of K < + >, Rb < + > and Cs < + > aiming at a specific lithium precipitation mother liquor system with high potassium ion concentration and low-content rubidium ions and cesium ions, and can effectively avoid the loss of Rb < + > and Cs < + > and improve the purity of Rb < + > and Cs < + > in the separation process; in addition, the separation method can greatly reduce the use amount of the extraction agent and the acid-base.

Description

Technical Field

[0001] This invention belongs to the field of lithium precipitation mother liquor treatment technology, and particularly relates to a method for separating potassium, rubidium and cesium from lithium precipitation mother liquor using a combination of extraction and electrochemical methods. Background Technology

[0002] Potassium resources are crucial for ensuring high grain yields and sustainable agricultural development. They are also a core chemical raw material in many industrial sectors, and their stable supply is vital for both agricultural foundations and industrial development. Rubidium, cesium, and their compounds, due to their excellent photoelectric effect and special properties, are widely used in phototubes, magnetohydrodynamic generators, and other fields, making them important strategic resources. Rubidium and cesium have highly similar chemical properties and rarely exist as standalone minerals in nature, usually occurring as associated minerals. Lepidolite is a significant source of rubidium and cesium, accounting for 55% of my country's total rubidium-bearing ore resources.

[0003] The main methods for extracting rubidium and cesium from lithium precipitation mother liquor include extraction, adsorption, and precipitation. Precipitation separates rubidium and cesium by reacting ions with phosphotungstenate to form a precipitate. It is simple to operate and has a high recovery rate, but the precipitation process is complex, the precipitate has poor stability, and it is environmentally damaging. Adsorption avoids the use of organic solvents, making it relatively safe and environmentally friendly. It has a high adsorption rate and good selectivity, but it has the problem of difficulty in effectively separating potassium, rubidium, and cesium, affecting product quality. Extraction is rapid, has a large processing capacity, and is simple to operate. A 4-tert-butyl-2-(α-benzyl)phenol (t-BAMBP) + sulfonated kerosene extraction system can effectively extract potassium from lithium precipitation mother liquor. + 、Rb + 、Cs + With Li + Na + Separation is possible, but due to the similar physical and chemical properties of potassium, rubidium, and cesium, K can be achieved. + 、Rb + 、Cs + Separation requires multi-stage countercurrent extraction, washing, and back-extraction, which results in the loss of rubidium and cesium. In particular, the separation coefficients for rubidium and potassium are low, making it difficult to separate K+ from lithium in high-potassium lithium precipitation mother liquor. + 、Rb + Effective separation can be achieved. However, solvent extraction methods suffer from high alkali consumption, significant solubility loss, demanding equipment requirements, and environmental pollution caused by acids and alkalis during the extraction process, which severely restricts their industrial application.

[0004] Based on this, a novel method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor has been studied. This method not only effectively separates potassium, rubidium, and cesium but also avoids the loss of rubidium and cesium while increasing Rb. + 、Cs + Purity. Summary of the Invention

[0005] Objective of the invention: This invention provides a method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using an extraction-electrochemical coupling process. This method can efficiently separate potassium. + 、Rb + 、Cs + Furthermore, it effectively avoids rubidium and cesium loss during the separation process while increasing Rb. + 、Cs + It ensures high purity and significantly reduces the amount of extractant and acid / alkali used, simplifying the process and lowering costs.

[0006] Technical solution: The present invention provides a method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling, comprising the following steps:

[0007] (1) After pretreatment of the lithium precipitation mother liquor, adjust its pH value to alkaline, add potassium stabilizer to complex with potassium ions in the lithium precipitation mother liquor to obtain solution A.

[0008] (2) The solution A was subjected to cesium extraction to obtain the cesium-extracted organic phase and the raffinate containing potassium and rubidium;

[0009] (3) Using the potassium and rubidium-containing raffinate as the electrolyte, and using the rubidium ion selective electrode active material as the cathode for electrochemical adsorption, a rubidium-containing adsorbed sample and a potassium-containing complex adsorbed liquid were obtained.

[0010] (4) Desorb the rubidium-containing adsorbed sample from step (3) and back-extract the cesium-containing organic phase from step (2) to obtain rubidium-containing salt solution, cesium-containing salt solution and potassium-containing complex solution respectively.

[0011] This invention employs an extraction-electrochemical combined method to separate potassium, rubidium, and cesium ions from lithium precipitation mother liquor. Specifically, cesium is first effectively extracted using extraction, followed by highly selective electrochemical adsorption of rubidium and potassium. In this lithium precipitation mother liquor system containing high concentrations of potassium ions and small amounts of rubidium and cesium, this method effectively avoids the loss of rubidium and cesium compared to existing pure extraction or precipitation methods.

[0012] In the extraction process, the pH of the lithium precipitation mother liquor is first adjusted to alkaline, and a potassium stabilizer is added to complex potassium ions. Adjusting the pH to alkaline not only works synergistically with the extractant to create an optimal extraction system for cesium, but also, under these alkaline conditions, tartaric acid is used to complex potassium ions, improving the water solubility of the potassium stabilizer in the system and further promoting complexation with potassium ions. This reduces the amount of high-concentration potassium ions from the lithium precipitation mother liquor entering the cesium extract during the extraction process, thus increasing the purity of cesium in the extract. Simultaneously, based on the optimal complexation of potassium stabilizer with potassium ions, when using electrochemical electroadsorption of rubidium, the reduction potential of potassium is reduced, increasing the difference in reduction potential between potassium and rubidium, achieving higher selective adsorption of rubidium while reducing the adsorption of potassium ions, thereby improving the purity of rubidium.

[0013] Furthermore, in step (1) of the separation method, the potassium stabilizer is one or more of tartaric acid, salicylaldehyde, and benzo-15-crown-5.

[0014] Furthermore, in this separation method, the amount of potassium stabilizer added is 0.5-1.5 times the theoretical molar amount of potassium ions that can be complexed.

[0015] Furthermore, in step (1) of this separation method, the adjusted pH value reaches 11-14. Preferably, the adjusted pH value reaches 12.5-13.5.

[0016] Furthermore, in step (3) of the separation method, the extractant used for cesium extraction is a mixed solution composed of 4-tert-butyl-2-(α-benzyl)phenol and a diluent, wherein the diluent includes one or more of 260# solvent oil, xylene, cyclohexane, and carbon tetrachloride.

[0017] Furthermore, in step (3) of this separation method, the active material of the rubidium ion selective electrode is composed of one or more of cobalt ferrocyanide, nickel ferrocyanide, manganese ferrocyanide, copper ferrocyanide, and activated carbon. Preferably, it can be one or more of copper ferrocyanide, cobalt ferrocyanide, or activated carbon.

[0018] Furthermore, in step (3) of the separation method, the applied voltage for electrochemical adsorption is 0.3-2.5V, and the adsorption time is 10-40min.

[0019] Furthermore, in step (4) of the separation method, the rubidium-containing adsorbed sample is desorbed by immersing it in a sulfuric acid solution with a concentration of 0.01-1.0 mol / L and desorbing it for 10-40 min under an applied voltage of -1.0 to -0.2 V.

[0020] Beneficial effects: Compared with the prior art, the significant advantage of this invention is that this separation method is specifically designed for lithium precipitation mother liquor systems with high potassium ion concentration and low rubidium and cesium ion content, and can effectively improve K + 、Rb + 、Cs + The separation efficiency of the three components is optimized to avoid interference from competition among them, and Rb can be effectively avoided during the separation process. + 、Cs + This method reduces the loss of extractant and improves the purity of both components; furthermore, it significantly reduces the amount of extractant and acid / alkali used, simplifies the process, and lowers separation costs. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the extraction-electrochemical combined separation in Example 1 of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] In the following embodiments of the present invention, the separation coefficient is calculated by the following formula:

[0024]

[0025] In the formula: [C A ] O [C] B ] O This represents the concentrations of substances A and B in non-aqueous solutions, expressed in g / L.

[0026] [C A ] aq [C] B ] aq It represents the concentrations of substances A and B in aqueous solution, in g / L.

[0027] The washing rate in the following embodiments of the present invention is calculated using the following formula:

[0028]

[0029] In the formula: [M] O1 [M] O2 These represent the equilibrium concentrations of metal ions in the loaded organic phase before and after washing, in g / L.

[0030] Purity description: Cs + / Rb + In solution, cations (Li) + Na + K + 、Rb+ 、Cs + (%) of mass concentration.

[0031] The main component contents of the lithium precipitation mother liquor used in the following embodiments of the present invention are shown in Table 1 below.

[0032] Table 1. Main Component Contents of Lithium-Condensed Mother Liquor

[0033] Li (g / L) Na(g / L) K(g / L) Rb(g / L) Cs(g / L) 5.32 43.2 40.5 1.833 1.243

[0034] Furthermore, in Example 1 of the present invention, the extractant used was a mixed solution composed of 4-tert-butyl-2-(α-benzyl)phenol and 260# solvent oil, wherein the mass fraction of 4-tert-butyl-2-(α-benzyl)phenol in the mixed solution was 30%. The potassium stabilizer used in the following examples was tartaric acid.

[0035] In the electrochemical device used in the following embodiments of the present invention, the working electrode is copper ferricyanide; the counter electrode is a platinum sheet; and the reference electrode is Ag / AgCl.

[0036] Example 1

[0037] The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using the extraction-electrochemical coupling method in Example 1 is as follows: Figure 1 As shown, the specific steps include the following:

[0038] (1) The lithium precipitation mother liquor was passed through a precision filter (pore size 0.45μm) to remove suspended solids. Then, the pH was adjusted to 12.5-13.5 with 30% NaOH solution and 1.5mol / L tartaric acid was added to obtain solution 1. The amount of tartaric acid added was 1.4 times the theoretical molar amount of potassium ions to be complexed.

[0039] (2) Add 100 mL of extractant to 400 mL of solution 1 for three-stage extraction, with each stage lasting 2 min. After extraction and separation, the oil phase is the first extract and the aqueous phase is the first raffinate. The K content of the first raffinate is determined. + 、Rb + 、Cs + Concentration to obtain K + The extraction rate was 1.6%, Rb + The extraction rate was 28.3%, Cs + The extraction rate was 99.2%, and the separation coefficient (β) of cesium and rubidium after three-stage extraction was [missing information]. Cs / Rb The value is 314.2;

[0040] (3) Add 0.001 mol / L sulfuric acid to the first extract solution for four-stage washing, each stage lasting 5 min. The oil phase is the first extract solution, and the aqueous phase is the first washing solution. Measure the K in the first washing solution. +、Rb + 、Cs + Concentration to obtain K + Washing rate 99.8%, Rb + The washing rate was 94.5%, Cs + The washing rate is 2.3%;

[0041] (4) Add 0.01 mol / L sulfuric acid to the first cesium extraction solution above for three-stage back-extraction, with each stage lasting 5 min, to obtain the aqueous phase as the first back-extraction solution. Determine the Li content in the first back-extraction solution. + Na + K + 、Rb + 、Cs + Concentration of Li + The proportion was 0.0014%, Na + The proportion was 0.0041%, K + The proportion was 0.055%, Rb + The proportion was 0.12%, Cs + The proportion was 99.82%;

[0042] (5) Place the first raffinate obtained in step (2) in an electrochemical device. After applying a voltage of 1.0V for 10 minutes, rubidium ions are selectively adsorbed and enriched by the corresponding electrodes in the corresponding flow electrode chambers to obtain the first adsorption sample. The solution is the first adsorption liquid. Measure the K in the first adsorption liquid. + 、Rb + Concentration to obtain K + The adsorption rate was 4.2%, Rb + The adsorption rate was 90.9%, and the separation coefficient of rubidium and potassium (β) was... Rb / K The value is 227.8;

[0043] (6) The first adsorbed sample was immersed in a 0.1 mol / L sulfuric acid solution and desorbed at a potential of -0.2 V for 15 min to obtain the first desorbed solution. The Li content of the first desorbed solution was then determined. + Na + K + 、Rb + 、Cs + Concentration of Li + The proportion was 0.0018%, Na + The proportion was 0.0018%, K + The proportion was 0.46%, Rb + The proportion was 99.53%, Cs + The percentage was 0.0088%.

[0044] In Example 1 above, the changes in the concentrations of each ion before and after extraction-electrochemical coupling are shown in Table 2.

[0045] Table 2. Changes in the concentration of various ions in the aqueous solution before and after extraction-electrochemical coupling in Example 1.

[0046] Components Li (g / L) Na(g / L) K(g / L) Rb(g / L) Cs(g / L) initial 5.32 43.2 40.5 1.833 1.243 First back-extraction liquid 0.0001 0.0003 0.004 0.009 7.331 First desorption liquid 0.0001 0.0001 0.026 5.700 0.0005

[0047] Comparative Example 1

[0048] The extraction method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor in a comparative manner includes the following specific steps:

[0049] (1) The lithium precipitation mother liquor was passed through a precision filter (pore size 0.45μm) to remove suspended solids, and then the pH was adjusted to 12.5-13.0 with 30% NaOH solution to obtain solution 1;

[0050] (2) Add 100 mL of extractant to 400 mL of solution 1 for three-stage extraction, with each stage lasting 2 min. After extraction and separation, the oil phase is the first extract and the aqueous phase is the first raffinate. Measure K from the first raffinate. + 、Rb + 、Cs + Concentration to obtain K + The extraction rate was 9.6%, Rb + The extraction rate was 24.3%, Cs + The extraction rate was 97.2%, and the separation coefficient β of cesium and rubidium after three-stage extraction was [missing information]. Cs / Rb It is 108.1;

[0051] (3) Add 0.001 mol / L sulfuric acid to the first extract solution for four-stage washing, each stage lasting 5 min. The oil phase is the first extract solution, and the aqueous phase is the first washing solution. Measure the K in the first washing solution. + 、Rb + 、Cs + Concentration to obtain K + The washing rate was 90.2%, Rb + The washing rate is 95.5%, Cs + The washing rate is 2.6%;

[0052] (4) Add 0.01 mol / L sulfuric acid to the first cesium extraction solution above for three-stage back-extraction, with each stage lasting 5 min, to obtain the aqueous phase as the first back-extraction solution. Determine the Li content in the first back-extraction solution. + Na + K + 、Rb + 、Cs + Concentration of Li + The proportion was 0.0014%, Na +The proportion was 0.0057%, K + The proportion was 0.44%, Rb + The proportion was 0.13%, Cs + The proportion was 99.42%;

[0053] (5) Add sodium hydroxide to the first raffinate obtained in step (2) to adjust the pH to 14, then add 100 mL of extractant and perform three-stage extraction to obtain the second extract. The aqueous phase is the second raffinate. Measure the K in the second raffinate. + 、Rb + Concentration to obtain K + The extraction rate was 18.2%, Rb + The extraction rate was 76.1%, and the separation coefficient (β) of rubidium and potassium in the three-stage extraction was [missing information]. Rb / K The value is 14.3 (<20);

[0054] (6) Add pure water to the second extract above and perform four-stage washing, each stage lasting 5 minutes. The oil phase is the first extract solution, and the aqueous phase is the first washing solution. Measure K in the first washing solution. + 、Rb + Concentration to obtain K + The washing rate was 97.8%, Rb + The washing rate was 62.5%;

[0055] (7) Add 0.01 mol / L sulfuric acid to the first rubidium extraction solution above for secondary back-extraction, with each back-extraction time being 5 min, to obtain the aqueous phase as the second back-extraction solution. Determine the Li content in the second back-extraction solution. + Na + K + 、Rb + 、Cs + Concentration of Li + The proportion of Na is 0%. + The proportion was 0.0026%, K + The proportion was 13.24%, Rb + The proportion was 86.74%, Cs + The proportion was 0.021%.

[0056] In Comparative Example 1 above, the changes in the concentrations of each ion before and after extraction-electrochemical coupling are shown in Table 3.

[0057] Table 3. Changes in the concentration of various ions in the aqueous solution before and after continuous extraction in Comparative Example 1.

[0058] Components Li (g / L) Na(g / L) K(g / L) Rb(g / L) Cs(g / L) initial 5.32 43.2 40.5 1.833 1.243 First back-extraction liquid 0.0001 0.0004 0.031 0.009 7.001 Second stripping solution 0 0.0001 0.507 3.322 0.0008

[0059] As can be seen from Example 1 and Comparative Example 1, by employing the separation method of the present invention, after pre-complexing potassium ions to form a stable aqueous solution system, and then combining extraction and electrochemical separation, the separation coefficient (β) of cesium and rubidium after three-stage extraction can be improved. Cs / Rb The rubidium and potassium separation coefficient (β) can reach 314.2. Rb / K The concentration can reach 227.8. Furthermore, the Cs content in the first back-extraction solution... + The purity can reach 99.82%, K + The proportion is only 0.055%, Rb + The proportion was only 0.12%. In the first desorption solution after electrochemical adsorption and desorption, Rb + The purity can reach 99.53%, K + The proportion was only 0.46%, Cs + The proportion was only 0.0088%.

[0060] In contrast, Comparative Example 1 used a continuous extraction method, and the separation coefficient β of cesium and rubidium after three-stage extraction was [missing value]. Cs / Rb The rubidium and potassium separation coefficient (β) is only 108.1. Rb / K The value was only 14.3. In the first back-extraction solution, Cs + The purity is 99.42%, K + The proportion reached 0.44%, Rb + The proportion was 0.13%. In the second back-extraction solution, Rb... + The purity is only 86.74%, K + The proportion reached 13.24%, Cs + The proportion was 0.021%.

[0061] Therefore, in systems with high potassium content, when using stepwise extraction, the coexistence of potassium ions, rubidium ions, and cesium ions in the extraction system will affect each other, leading to a decrease in the separation efficiency of potassium ions, rubidium ions, and cesium ions, and a decrease in the purity of rubidium and cesium products.

[0062] Example 2

[0063] The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using the extraction-electrochemical coupling method in Example 2 specifically includes the following steps:

[0064] (1) The lithium precipitation mother liquor was passed through a precision filter (pore size 0.45 μm) to remove suspended solids. Then, the pH was adjusted to 12.5-13.5 with 30% NaOH solution and 0.6 mol / L tartaric acid was added to obtain solution 1. The amount of tartaric acid added was 0.56 times the theoretical molar amount of potassium ions to be complexed.

[0065] (2) Add 100 mL of extractant to 400 mL of solution 1 for three-stage extraction, with each stage lasting 2 min. After extraction and separation, the oil phase is the first extract and the aqueous phase is the first raffinate. The K content of the first raffinate is determined. + 、Rb + 、Cs + Concentration to obtain K + The extraction rate was 3.4%, Rb + The extraction rate was 29.3%, Cs + The extraction rate was 98.7%, and the separation coefficient (β) of cesium and rubidium after three-stage extraction was [missing information]. Cs / Rb The value is 183.2 (>150);

[0066] (3) Add 0.001 mol / L sulfuric acid to the first extract solution for four-stage washing, each stage lasting 5 min. The oil phase is the first extract solution, and the aqueous phase is the first washing solution. Measure the K in the first washing solution. + 、Rb + 、Cs + Concentration to obtain K + Washing rate 95.2%, Rb + The washing rate was 96.2%, Cs + The washing rate was 3.1%;

[0067] (4) Add 0.01 mol / L sulfuric acid to the first cesium extraction solution above for three-stage back-extraction, with each stage lasting 5 min, to obtain the aqueous phase as the first back-extraction solution. Determine the Li content in the first back-extraction solution. + Na + K + 、Rb + 、Cs + Concentration of Li + The proportion of Na is 0%. + The proportion was 0.0042%, K + The proportion was 0.14%, Rb + The proportion was 0.15%, Cs + The proportion was 99.71%;

[0068] (5) Place the first raffinate obtained in step (2) in an electrochemical device. After applying a voltage of 1.0V for 10 minutes, rubidium ions are selectively adsorbed and enriched by the corresponding electrodes in the corresponding flow electrode chambers to obtain the first adsorption sample. The solution is the first adsorption liquid. Measure the K in the first adsorption liquid. + 、Rb + Concentration to obtain K + The adsorption rate was 10.6%, Rb + The adsorption rate was 92.4%, and the separation coefficient of rubidium and potassium (β) was... Rb / K The value is 102.5 (>65);

[0069] (6) The first adsorbed sample was immersed in a 0.1 mol / L sulfuric acid solution and desorbed at a potential of -0.2 V for 15 min to obtain the first desorbed solution. The Li content of the first desorbed solution was then determined. + Na + K + 、Rb + 、Cs + Concentration of Li + The proportion was 0.0017%, Na + The proportion was 0.0034%, K + The proportion was 1.47%, Rb + The proportion of 98.52% was α, and the proportion of Cs+ was 0.051%.

[0070] In Comparative Example 2 above, the changes in the concentrations of each ion before and after extraction-electrochemical coupling are shown in Table 4.

[0071] Table 4. Changes in the concentration of various ions in the aqueous solution before and after extraction-electrochemical coupling in Comparative Example 2.

[0072]

[0073]

[0074] Example 3

[0075] The basic steps are the same as in Example 1, except that the adsorption voltage in electrochemical adsorption is changed to 2.0V.

[0076] In Example 3, the changes in the concentrations of each ion before and after extraction-electrochemical coupling are shown in Table 5.

[0077] Table 5. Changes in the concentration of various ions in the aqueous solution before and after extraction-electrochemical coupling in Example 3.

[0078] Components Li (g / L) Na(g / L) K(g / L) Rb(g / L) Cs(g / L) initial 5.32 43.2 40.5 1.833 1.243 First back-extraction liquid 0.0002 0.0002 0.004 0.011 7.425 First desorption liquid 0 0.0003 0.145 7.643 0.0008

[0079] Based on the data results in Table 5 of Example 3, it can be seen that the purity of cesium can reach 99.79%, and the purity of rubidium ions can reach 98.12%.

[0080] Example 4

[0081] The basic steps are the same as in Example 1, except that the adsorption time in electrochemical adsorption is changed to 20 min.

[0082] In Example 4, the changes in the concentrations of each ion before and after extraction-electrochemical coupling are shown in Table 6.

[0083] Table 6. Changes in the concentration of various ions in the aqueous solution before and after extraction-electrochemical coupling in Example 3.

[0084] Components Li (g / L) Na(g / L) K(g / L) Rb(g / L) Cs(g / L) initial 5.32 43.2 40.5 1.833 1.243 First back-extraction liquid 0 0 0.007 0.006 7.239 First desorption liquid 0.0001 0.0005 0.256 7.267 0.0003

[0085] Comparative Example 2

[0086] The basic steps are the same as in Example 4, except that tartaric acid is not added.

[0087] In Comparative Example 2, the changes in the concentrations of each ion before and after extraction-electrochemical coupling are shown in Table 7.

[0088] Table 7. Changes in the concentrations of various ions in the aqueous solution before and after extraction-electrochemical coupling in Comparative Example 2.

[0089]

[0090]

[0091] Combining the data from Example 4 and Comparative Example 2, it can be seen that the purity of cesium in Example 4 reaches 99.82%, and the purity of rubidium ions reaches 96.59%; while in Comparative Example 2, without the addition of potassium stabilizer, the purity of cesium is 99.45%, and the purity of rubidium ions reaches 92.44%. Therefore, the addition of potassium stabilizer can improve the separation purity of rubidium and cesium, achieving efficient separation of the three components while increasing the purity of the rubidium and cesium products and reducing interference from potassium ions.

[0092] In addition to the above embodiments, the separation step parameters and substances used as defined in this invention can also achieve the effect of increasing K as claimed in this invention. + 、Rb + 、Cs + The separation efficiency of the three components, and the ability to effectively avoid Rb during the separation process. + 、Cs + To reduce losses and improve the purity of both.

[0093] For example, in the separation step (1) of the present invention, the pH value can be adjusted to 11-14. The potassium stabilizer used can also be one or more of tartaric acid, salicylaldehyde, and benzo-15-crown-5, and the amount added is 0.5-1.5 times the theoretical molar amount of potassium ions to be complexed.

[0094] For example, in separation step (2), the diluent used in the extractant can also be one or more of 260# solvent oil, xylene, cyclohexane, and carbon tetrachloride.

[0095] In separation step (3), the working electrode material may be one or more of cobalt ferrocyanide, nickel ferrocyanide, manganese ferrocyanide, copper ferrocyanide, or activated carbon. Preferably, it may be one or more of copper ferrocyanide, cobalt ferrocyanide, or activated carbon. The applied voltage during electrochemical adsorption may be 0.3-2.5V, and the adsorption time may be 10-40min, preferably 10-20min.

[0096] In the separation step (3), the concentration of the sulfuric acid solution used for electrochemical desorption of the rubidium-adsorbed sample can be 0.01-1.0 mol / L, the desorption voltage can be -1.0 to -0.2 V, and the desorption time can be 10-40 min.

Claims

1. A method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling, characterized in that, Includes the following steps: (1) After pretreatment of the lithium precipitation mother liquor, adjust its pH value to alkaline, add potassium stabilizer to complex with potassium ions in the lithium precipitation mother liquor to obtain solution A. (2) The solution A was subjected to cesium extraction to obtain the cesium-extracted organic phase and the raffinate containing potassium and rubidium; (3) Using the potassium and rubidium-containing raffinate as the electrolyte, and using the rubidium ion selective electrode active material as the working electrode for electrochemical adsorption, a rubidium-containing adsorbed sample and a potassium-containing complex adsorbed liquid were obtained. (4) Desorb the rubidium-containing adsorbed sample from step (3) and back-extract the cesium-containing organic phase from step (2) to obtain rubidium-containing salt solution, cesium-containing salt solution and potassium-containing complex solution respectively.

2. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1, characterized in that, In step (1), the potassium stabilizer is one or more of tartaric acid, salicylaldehyde, and benzo-15-crown-5.

3. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1 or 2, characterized in that, The amount of potassium stabilizer added is 0.5-1.5 times the theoretical molar amount of potassium ions that can be complexed.

4. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1, characterized in that, In step (1), the adjusted pH value reaches 11-14.

5. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 4, characterized in that, The adjusted pH value reaches 12.5-13.

5.

6. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1, characterized in that, In step (3), the extractant used for cesium extraction is a mixed solution composed of 4-tert-butyl-2-(α-benzyl)phenol and a diluent, wherein the diluent includes one or more of 260# solvent oil, xylene, cyclohexane, and carbon tetrachloride.

7. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1, characterized in that, In step (3), the active material of the rubidium ion selective electrode is one or more of cobalt ferrocyanide, nickel ferrocyanide, manganese ferrocyanide, copper ferrocyanide, or activated carbon.

8. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 7, characterized in that, The active material of the rubidium ion selective electrode is one or more of copper ferrocyanide, cobalt ferrocyanide, or activated carbon.

9. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1, characterized in that, In step (3), the applied voltage for electrochemical adsorption is 0.3-2.5V, and the adsorption time is 10-40min.

10. The method for separating potassium, rubidium, and cesium from lithium precipitation mother liquor using extraction-electrochemical coupling according to claim 1, characterized in that, In step (4), the rubidium-containing adsorbed sample is desorbed by immersing it in a sulfuric acid solution with a concentration of 0.01-1.0 mol / L and desorbing it for 10-40 min under a voltage condition of -1.0 to -0.2 V.

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