Method for extracting and separating lithium from solution with high sodium-lithium ratio

Abstract

The invention provides a method for extracting and separating lithium from a solution with a high sodium-lithium ratio, and relates to the field of hydrometallurgy. The method for extracting and separating the lithium from the solution with the high sodium-lithium ratio comprises the following steps: mixing a water phase containing lithium and sodium with an organic phase, extracting, standing and splitting phases to obtain a lithium-loaded organic phase and raffinate; wherein the organic phase comprises an extraction agent, a synergistic extraction agent and a diluent, the extraction agent comprises PMBP, the synergistic extraction agent comprises TRPO, the diluent comprises at least one of sulfonated kerosene and light white oil, and the mass ratio of sodium to lithium in the lithium-containing sodium water phase is greater than or equal to 80; mixing the lithium-loaded organic phase with a washing solution, and washing to remove co-extracted sodium; and mixing the washed organic phase with the strip liquor, carrying out reverse extraction, and carrying out standing and phase splitting to obtain a lithium-rich strip liquor and a regenerated organic phase. The method provided by the invention can realize efficient separation of lithium and sodium from the solution with high sodium-to-lithium ratio, and has the advantages of high lithium extraction rate, low sodium co-extraction rate, rapid phase separation and complete reverse extraction.

Description

Technical Field

[0001] This application relates to the field of hydrometallurgy, and more particularly to a method for extracting and separating lithium from a solution with a high sodium-to-lithium ratio. Background Technology

[0002] Lithium is an important strategic resource, widely used in batteries, ceramics, glass, lubricants, and the nuclear industry. Salt lake brines are one of the main forms of global lithium storage. In my country, such as Qinghai, the extraction of lithium from salt lake brines using the sodium carbonate precipitation method produces a large amount of lithium-ion precipitate mother liquor with a high sodium-to-lithium ratio. This mother liquor has an extremely high sodium ion concentration and a relatively low lithium ion concentration, with a sodium-to-lithium mass ratio exceeding 80. Further recovery of lithium from this type of mother liquor is of great significance for improving the overall recovery rate of lithium resources and reducing costs.

[0003] Solvent extraction is a highly efficient technique for separating lithium and sodium from lithium precipitation mother liquor. However, existing extraction methods generally suffer from problems such as high sodium co-extraction rates, difficulty in phase separation, and low back-extraction efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a method for extracting and separating lithium from a solution with a high sodium-to-lithium ratio, in order to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution: A method for extracting and separating lithium from a high sodium-to-lithium ratio solution, comprising: A lithium-containing sodium aqueous phase is mixed with an organic phase and extracted. After standing and phase separation, a lithium-loaded organic phase and raffinate are obtained. The organic phase includes an extractant, a co-extractant, and a diluent. The extractant includes PMBP, the co-extractant includes TRPO, and the diluent includes at least one of sulfonated kerosene and light white oil. The mass ratio of sodium to lithium in the lithium-containing sodium aqueous phase is greater than or equal to 80. The lithium-loaded organic phase is mixed with a washing solution and washed to remove the co-extracted sodium. The washed organic phase was mixed with the back-extraction solution and back-extracted. After standing and phase separation, lithium-rich back-extraction solution and regenerated organic phase were obtained.

[0006] According to an embodiment of this application, the sodium ion concentration in the lithium-containing sodium aqueous phase is 100-150 g / L, and the lithium ion concentration in the lithium-containing sodium aqueous phase is 1-2 g / L; And / or, the lithium-containing sodium aqueous phase is a lithium-precipitated mother liquor from a salt lake.

[0007] According to an embodiment of this application, before extraction, the method further includes: adjusting the initial pH of the lithium sodium-containing aqueous phase to 10-13, and then mixing the lithium sodium-containing aqueous phase with an initial pH of 10-13 with the organic phase.

[0008] According to an embodiment of this application, in the extraction step, the volume ratio O / A of the organic phase to the lithium-sodium aqueous phase is 2:1 to 4:1.

[0009] According to an embodiment of this application, in the extraction step, the molar ratio of the extractant to lithium in the aqueous phase is 1.0 to 2.5:1.

[0010] According to embodiments of this application, the volume concentration of the co-extractant in the organic phase is 10% to 35%.

[0011] According to an embodiment of this application, the extraction time is 0.5-5 minutes.

[0012] According to an embodiment of this application, the washing liquid includes a hydrochloric acid solution with a concentration of 1% to 3%; And / or, in the washing step, the volume ratio O / A of the lithium-loaded organic phase to the washing liquid is 10:1 to 20:1.

[0013] According to an embodiment of this application, the back-extraction solution comprises a hydrochloric acid solution with a concentration of 20% to 30%.

[0014] According to an embodiment of this application, in the back-extraction step, the volume ratio O / A of the washed organic phase to the back-extraction solution is 20:1 to 40:1; And / or, the method further includes: returning the regenerated organic phase to the extraction step for recycling.

[0015] Compared with the prior art, the beneficial effects of this application include: The method described in this application enables efficient separation of lithium and sodium from solutions with a high sodium-to-lithium ratio, offering advantages such as high lithium extraction rate, low sodium co-extraction rate, rapid phase separation, and complete back-extraction. Specifically, it includes: 1. High selectivity: The lithium extraction rate can reach over 90%, while the sodium co-extraction rate is only about 3%, exhibiting an extremely high separation coefficient.

[0016] 2. Excellent phase separation performance: effectively avoids emulsification and the formation of a third phase, and phase separation is rapid and thorough.

[0017] 3. Recyclable: The organic phase after back-extraction is stable and can be returned to the extraction process for recycling, reducing operating costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0019] Figure 1This is a flowchart of the method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to this application. Detailed Implementation

[0020] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0021] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0022] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0023] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0024] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0025] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0026] This application provides a method for extracting and separating lithium from a solution with a high sodium-to-lithium ratio, referencing... Figure 1 ,include: A lithium-containing sodium aqueous phase is mixed with an organic phase and extracted. After standing and phase separation, a lithium-loaded organic phase and raffinate are obtained. The organic phase includes an extractant, a co-extractant, and a diluent. The extractant includes PMBP, the co-extractant includes TRPO, and the diluent includes at least one of sulfonated kerosene and light white oil. The mass ratio of sodium to lithium in the lithium-containing sodium aqueous phase is greater than or equal to 80. The lithium-loaded organic phase is mixed with a washing solution and washed to remove the co-extracted sodium. The washed organic phase was mixed with the back-extraction solution and back-extracted. After standing and phase separation, lithium-rich back-extraction solution and regenerated organic phase were obtained.

[0027] 1-Phenylacetyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) is an extractant with the ability to complex lithium ions, but it has limitations in extraction capacity and is prone to emulsification when used alone. Trialkylphosphine oxide (TRPO) can be used as a co-extractant and phase modifier.

[0028] The method described in this application has the advantages of short process flow, high separation efficiency, good phase separation performance, and easy industrialization, and is particularly suitable for recovering lithium from lithium mother liquor precipitated from salt lakes.

[0029] In some embodiments, the mass ratio of sodium to lithium in the sodium-containing aqueous phase is 80, 82, 85, 87, 90, 92, 95, 97, 100 or any value greater than or equal to 80.

[0030] According to embodiments of this application, the sodium ion concentration in the lithium-containing sodium aqueous phase is 100-150 g / L, and the lithium ion concentration in the lithium-containing sodium aqueous phase is 1-2 g / L; for example, the sodium ion concentration in the lithium-containing sodium aqueous phase is any value between 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L, 135 g / L, 140 g / L, 145 g / L, 150 g / L, or 100-150 g / L, and the lithium ion concentration in the lithium-containing sodium aqueous phase is any value between 1 g / L, 1.5 g / L, 2 g / L, or 1-2 g / L.

[0031] In some embodiments, the sodium ion concentration in the lithium-sodium aqueous phase is 122.9 g / L and the lithium ion concentration is 1.414 g / L.

[0032] And / or, the lithium-containing sodium aqueous phase is a lithium-precipitated mother liquor from a salt lake.

[0033] According to an embodiment of this application, before extraction, the method further includes: adjusting the initial pH of the lithium-sodium aqueous phase to 10-13, and then mixing the lithium-sodium aqueous phase with an initial pH of 10-13 with an organic phase. When the initial pH of the lithium-sodium aqueous phase is too low, the lithium extraction efficiency decreases; when the initial pH of the lithium-sodium aqueous phase is too high, the extractant dissolution loss increases.

[0034] The pH conditions required for extraction in this application match the alkaline environment of the lithium precipitation solution in industrial production, requiring no major adjustments and facilitating industrial application. In other words, this application also has the advantage of good process integration.

[0035] For example, the initial pH of the lithium-sodium aqueous phase is 10, 11, 12, 13, or any value between 10 and 13.

[0036] According to embodiments of this application, in the extraction step, the volume ratio O / A of the organic phase to the lithium-sodium-containing aqueous phase is 2:1 to 4:1. For example, the volume ratio O / A of the organic phase to the lithium-sodium-containing aqueous phase is any value between 2:1, 3:1, 4:1, or 2:1 to 4:1.

[0037] According to embodiments of this application, in the extraction step, the molar ratio of the extractant to lithium in the aqueous phase is 1.0 to 2.5:1. When this molar ratio is too low, the extraction efficiency decreases; when this molar ratio is too high, the acid and alkali consumption in the extraction process increases.

[0038] For example, the molar ratio of the extractant to lithium in the aqueous phase can be 1.0:1, 1.5:1, 2.0:1, 2.5:1, or any value between 1.0 and 2.5:1.

[0039] According to embodiments of this application, the volume concentration of the co-extractant in the organic phase is 10% to 35%. When the volume concentration of the co-extractant is too low, the lithium extraction efficiency is low; when the volume concentration of the co-extractant is too high, the viscosity of the extraction system increases, which is not conducive to phase separation.

[0040] For example, the volume concentration of the co-extractant in the organic phase is 10%, 15%, 20%, 25%, 30%, 35%, or any value between 10% and 35%.

[0041] According to embodiments of this application, the extraction time is 0.5-5 minutes. This application also has the advantage of a short extraction time, significantly reducing the process time.

[0042] For example, the extraction time can be any value between 0.5 minutes, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, or 0.5-5 minutes.

[0043] According to an embodiment of this application, the washing liquid includes a hydrochloric acid solution with a concentration of 1% to 3%; for example, the concentration of the hydrochloric acid solution in the washing liquid is 1%, 2%, 3%, or any value between 1% and 3%.

[0044] In the washing step, the volume ratio O / A of the lithium-loaded organic phase to the washing liquid is 10:1 to 20:1. For example, the volume ratio O / A of the lithium-loaded organic phase to the washing liquid is 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1 or any value between 10:1 and 20:1.

[0045] According to embodiments of this application, the back-extraction solution comprises a hydrochloric acid solution with a concentration of 20% to 30%. For example, the concentration of the hydrochloric acid solution in the back-extraction solution is any value between 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or 20% to 30%.

[0046] According to an embodiment of this application, in the back-extraction step, the volume ratio O / A of the washed organic phase to the back-extraction solution is 20:1 to 40:1; for example, the volume ratio O / A of the washed organic phase to the back-extraction solution is any value between 20:1, 25:1, 30:1, 35:1, 40:1 or 20:1 to 40:1.

[0047] The method further includes: returning the regenerated organic phase to the extraction step for recycling.

[0048] The embodiments of this application will be described in detail below with reference to specific examples and comparative examples. However, those skilled in the art will understand that the following content is only for illustrating this application and should not be regarded as limiting the scope of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments used are not specified, they are all conventional products that can be purchased commercially.

[0049] Example 1: Effect of PMBP dosage and lithium molar ratio on separation performance Examples 1-1 to 1-5 provide a method for extracting and separating lithium from a high sodium-to-lithium ratio solution, comprising the following steps: The lithium-containing sodium aqueous phase was mixed with the organic phase and extracted. After standing and phase separation, a lithium-loaded organic phase and raffinate were obtained. The lithium-containing sodium aqueous phase was a simulated lithium precipitation mother liquor, with a sodium ion concentration of 122.9 g / L, a lithium ion concentration of 1.414 g / L, and a sodium-to-lithium mass ratio of 87. The initial pH of the lithium-containing sodium aqueous phase was adjusted to 12 using NaOH. The organic phase included the extractant PMBP, the co-extractant TRPO, and the diluent sulfonated kerosene. The volume concentration of the co-extractant TRPO in the organic phase was 13.3%. During extraction, the volume ratio (O / A) of the organic phase to the lithium-containing sodium aqueous phase was 3:1, and the extraction time was 1 minute. In Examples 1-1, 1-2, 1-3, 1-4, and 1-5, the molar ratios of the extractant PMBP to lithium in the aqueous phase were 1.06:1, 1.42:1, 1.77:1, 2.13:1, and 2.48:1, respectively.

[0050] The lithium-loaded organic phase was mixed with a washing solution and washed. The washing solution was a 2% (volume concentration) hydrochloric acid solution, and the volume ratio (O / A) of the lithium-loaded organic phase to the washing solution was 15:1. The mixing time was 10 minutes.

[0051] The washed organic phase was mixed with the back-extraction solution and back-extracted. After standing and phase separation, a lithium-rich back-extraction solution and a regenerated organic phase were obtained. The back-extraction solution was a 25% (volume concentration) hydrochloric acid solution. The volume ratio (O / A) of the washed organic phase to the back-extraction solution was 30:1, and the mixing time was 10 minutes.

[0052] The separation effects of Examples 1-1 to 1-5 are shown in Table 1.

[0053] Table 1. Comparison of separation effects in Examples 1-1 to 1-5

[0054] As shown in Table 1, when the molar ratio of extractant PMBP to Li in the aqueous phase is 1.77:1, the lithium extraction rate reaches over 90%. Further increasing the amount of extractant PMBP has limited effect on improving lithium extraction efficiency and will increase lithium loss during the washing step. Considering both efficiency and cost, the preferred molar ratio of extractant PMBP to lithium in the aqueous phase is 1.5~2.0:1.

[0055] Example 2: Effect of initial pH of aqueous phase on separation effect Examples 2-1 to 2-5 provide a method for extracting and separating lithium from a high sodium-to-lithium ratio solution. The steps are the same as those in Example 1, except that the molar ratio of the extractant PMBP to Li in the aqueous phase is 1.77:1; and the pH values ​​of the aqueous phase in Examples 2-1, 2-2, 2-3, 2-4, and 2-5 are 10, 11, 12, 13, and 14, respectively.

[0056] The separation effects of Examples 2-1 to 2-5 are shown in Table 2.

[0057] Table 2. Comparison of separation effects in Examples 2-1 to 2-5

[0058] Table 2 shows that the initial pH of the lithium-sodium aqueous phase adjusted to 10-13 all exhibited good separation effects. When the initial pH of the aqueous phase was 12, the lithium extraction rate was high (>90%), the sodium co-extraction rate was low (approximately 3%), the phase separation was rapid, and the pH environment matched that of the industrial lithium precipitation mother liquor, indicating that the optimal pH adjustment for the lithium-sodium aqueous phase was 12.

[0059] Example 3: Effect of TRPO volume concentration on separation efficiency Example 3 provides a method for extracting and separating lithium from a high sodium-to-lithium ratio solution. The steps are basically the same as those described in Example 1, except that the initial pH of the aqueous phase is 12, and the molar ratio of the extractant PMBP to lithium in the aqueous phase is 1.77:1. In Examples 3-1, 3-2, 3-3, 3-4, 3-5, and 3-6, the volume concentrations of the co-extractant TRPO in the organic phase are 6.7%, 13.3%, 20.0%, 26.7%, 33.3%, and 40.0%, respectively.

[0060] The separation effects of Examples 3-1 to 3-6 are shown in Table 3.

[0061] Table 3. Comparison of separation effects in Examples 3-1 to 3-6

[0062] Table 3 shows that the co-extractant TRPO exhibits good separation performance when its volume concentration in the organic phase is between 10% and 35%. If the concentration of TRPO is too low, it will lead to difficulty in dissolving the extractant PMBP; if the concentration is too high, it will result in slow phase separation. The preferred volume concentration of TRPO in the organic phase is 10% to 20%.

[0063] Example 4: The effect of hydrochloric acid concentration in the washing solution on the washing effect Examples 4-1 to 4-6 provide a method for extracting and separating lithium from a high sodium-to-lithium ratio solution, comprising the following steps: The lithium-loaded organic phase obtained in Example 2 at pH=12 was used.

[0064] The lithium-loaded organic phase was mixed with a washing solution and washed; wherein, in the washing step, the volume ratio (O / A) of the organic phase to the washing solution was 15:1. The washing solutions in Examples 4-1 to 4-6 were hydrochloric acid solutions with concentrations of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.5%, respectively.

[0065] After washing, the Na and Li contents in the backwash solution were analyzed, and the washing rate and loss rate were calculated. The results are shown in Table 4.

[0066] The backwash solution refers to the solution obtained after back-extraction by mixing the washed organic phase with the back-extraction solution.

[0067] Table 4. Comparison of washing effects in Examples 4-1 to 4-6

[0068] As shown in Table 4, washing with a 2% hydrochloric acid solution can increase the sodium washing rate to 71% while keeping the lithium loss rate at a low level (1.44%), thus achieving effective removal of sodium and effective retention of lithium.

[0069] Example 5: Comprehensive Process Flow Verification Example 5: The complete “extraction-washing-back-extraction” cycle was verified under the optimized conditions.

[0070] Example 5 provides a method for extracting and separating lithium from a solution with a high sodium-to-lithium ratio. The specific steps are as follows: 1 L of lithium-containing sodium aqueous phase was mixed with the organic phase and extracted. After standing and phase separation, a lithium-loaded organic phase and raffinate were obtained. The lithium-containing sodium aqueous phase was a simulated lithium precipitation mother liquor (sodium ion concentration of 122.9 g / L, lithium ion concentration of 1.414 g / L, sodium-lithium mass ratio of 87), and the initial pH of the aqueous phase was adjusted to 12 with NaOH. The organic phase included the extractant PMBP, the co-extractant TRPO, and the diluent sulfonated kerosene. The amount of PMBP used was 33.3 g (the molar ratio of PMBP to Li in the aqueous phase was 1.77:1), and 160 mL of TRPO (TRPO volume concentration in the organic phase was 16%) was dissolved in the sulfonated kerosene and the volume was adjusted to 1 L. Extraction was carried out at room temperature. During extraction, the organic phase and the lithium-containing sodium aqueous phase were mixed and shaken for 1 minute at a volume ratio of O / A = 3:1, and then allowed to stand and separate. The concentration of Li in the raffinate was measured to be approximately 0.14 g / L, the Li extraction rate was 90.1%, and the Na co-extraction rate was approximately 3.3%.

[0071] Washing: The lithium-loaded organic phase was washed for 10 minutes with a 2% (volume concentration) HCl solution at an O / A ratio of 15:1. After washing, the sodium washing rate was 71.4%, and the lithium washing loss rate was 1.44%.

[0072] Back-extraction: The washed organic phase was mixed with a 25% (volume concentration) HCl solution at a volume ratio of O / A = 30:1 for 10 minutes for back-extraction. The lithium back-extraction rate reached 98.1%.

[0073] Recycling: The regenerated organic phase after back-extraction is directly used for the next extraction. The above process is repeated 5 times, and the lithium extraction rate is still maintained above 89%, with stable phase separation performance.

[0074] Comparative Example 1: Using different extractants The difference between Comparative Example 1 and Example 5 is that the extractant was replaced with an equimolar amount of tributyl phosphate (TBP), while the co-extractant remained TRPO (with a volume concentration of 16% in the organic phase). Everything else was the same as in Example 5.

[0075] Results: In Comparative Example 1, the Li extraction rate was only 32.5%, while the Na co-extraction rate was as high as 25.1%, and severe emulsification occurred after phase separation. The washing and back-extraction steps were inefficient.

[0076] The comparison between Example 5 and Comparative Example 1 shows that TBP has a much lower selectivity for lithium in high sodium-lithium ratio solutions than PMBP, and cannot achieve effective separation.

[0077] Comparative Example 2: Without using the co-extractant TRPO The difference between Comparative Example 1 and Example 5 is that the organic phase contains only PMBP (the molar ratio of extractant PMBP to Li in the aqueous phase is 1.77:1) and sulfonated kerosene, and does not contain TRPO. Everything else is the same as in Example 5.

[0078] Results: PMBP dissolved very slowly and incompletely in sulfonated kerosene, forming a highly viscous organic phase. Li extraction yielded less than 60%, and phase separation was extremely difficult, resulting in a stubborn third phase. Effective subsequent washing and back-extraction were impossible.

[0079] The comparison between Example 5 and Comparative Example 2 shows that the extraction system cannot be constructed and operated normally without the co-extractant TRPO.

[0080] Comparative Example 3: Using different co-extractants The difference between Comparative Example 3 and Example 5 is that the co-extractant was replaced with an equal volume of trioctylphosphine oxide (TOPO). Everything else was the same as in Example 5.

[0081] Results: Li extraction rate was 85.2%, and Na co-extraction rate was 4.8%. The phase separation time was significantly longer than that of the TRPO system, and TOPO was expensive. The organic phase was slightly turbid after back-extraction.

[0082] The comparison between Example 5 and Comparative Example 3 shows that although TOPO has a certain synergistic extraction effect, its phase separation performance and cost-effectiveness are not as good as TRPO.

[0083] Comparative Example 4: No diluent used The difference between Comparative Example 4 and Example 5 is that the organic phase in Comparative Example 4 consists only of a mixture of PMBP and TRPO, without the addition of sulfonated kerosene. Everything else is the same as in Example 5.

[0084] Results: The organic phase in Comparative Example 4 was too viscous and could hardly be separated after mixing with the aqueous phase, forming a paste-like emulsion. No effective extraction data could be obtained.

[0085] The comparison between Example 5 and Comparative Example 4 shows that the diluent sulfonated kerosene is crucial and indispensable for adjusting the viscosity of the organic phase and improving the phase separation performance.

[0086] Comparative Example 5: Using different diluents The difference between Comparative Example 5 and Example 5 is that the diluent sulfonated kerosene was replaced with an equal volume of n-heptane. Everything else is the same as in Example 5.

[0087] Results: In Comparative Example 5, the Li extraction rate was 89.5%, and the Na co-extraction rate was 3.5%, which was comparable to that of sulfonated kerosene. However, n-heptane has high volatility and a low flash point, posing safety and environmental risks, and its cost is higher than that of sulfonated kerosene.

[0088] The comparison between Example 5 and Comparative Example 5 shows that sulfonated kerosene, as a diluent, has the comprehensive advantages of high safety and low cost while ensuring the extraction effect.

[0089] The comparison between the examples and comparative examples shows that using PMBP (molar ratio of extractant to lithium in the aqueous phase of 1.5~2.5:1) as the extractant, TRPO (volume concentration of 10%~35%) as the co-extractant, and sulfonated kerosene as the diluent, an organic phase can efficiently and selectively extract lithium from high sodium-to-lithium ratio solutions (extraction rate >90%, Na co-extraction rate of about 3%) under pH conditions of 10-13 (preferably 12). High-purity lithium recovery and recycling of the organic phase can be achieved through subsequent washing and back-extraction. The comparative examples further confirm the necessity and superiority of the components and conditions in the technical solution of this application.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0091] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for extracting and separating lithium from a solution with a high sodium-to-lithium ratio, characterized in that, include: A lithium-containing sodium aqueous phase is mixed with an organic phase and extracted. After standing and phase separation, a lithium-loaded organic phase and raffinate are obtained. The organic phase includes an extractant, a co-extractant, and a diluent. The extractant includes PMBP, the co-extractant includes TRPO, and the diluent includes at least one of sulfonated kerosene and light white oil. The mass ratio of sodium to lithium in the lithium-containing sodium aqueous phase is greater than or equal to 80. The lithium-loaded organic phase is mixed with a washing solution and washed to remove the co-extracted sodium. The washed organic phase was mixed with the back-extraction solution and back-extracted. After standing and phase separation, lithium-rich back-extraction solution and regenerated organic phase were obtained.

2. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, The sodium ion concentration in the sodium-containing aqueous phase is 100-150 g / L, and the lithium ion concentration in the sodium-containing aqueous phase is 1-2 g / L; And / or, the lithium-containing sodium aqueous phase is a lithium-precipitated mother liquor from a salt lake.

3. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, Prior to extraction, the method further includes adjusting the initial pH of the lithium sodium-containing aqueous phase to 10-13, and then mixing the lithium sodium-containing aqueous phase with an initial pH of 10-13 with the organic phase.

4. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, In the extraction step, the volume ratio O / A of the organic phase to the lithium-sodium aqueous phase is 2:1 to 4:

1.

5. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 4, characterized in that, In the extraction step, the molar ratio of the extractant to lithium in the aqueous phase is 1.0 to 2.5:

1.

6. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 5, characterized in that, The volume concentration of the co-extractant in the organic phase is 10% to 35%.

7. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, The extraction time is 0.5-5 minutes.

8. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, The washing solution includes a hydrochloric acid solution with a concentration of 1% to 3%; And / or, in the washing step, the volume ratio O / A of the lithium-loaded organic phase to the washing liquid is 10:1 to 20:

1.

9. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, The back-extraction solution comprises a hydrochloric acid solution with a concentration of 20% to 30%.

10. The method for extracting and separating lithium from a high sodium-to-lithium ratio solution according to claim 1, characterized in that, In the back-extraction step, the volume ratio O / A of the washed organic phase to the back-extraction solution is 20:1 to 40:1; And / or, the method further includes: returning the regenerated organic phase to the extraction step for recycling.

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