Amide extraction system and method for extracting lithium under alkaline condition

Abstract

The invention discloses an amide extraction system for extraction under an alkaline condition and a method thereof. The amide extraction system comprises an amide extraction agent, a synergistic extraction agent and a diluent; wherein the extractant amide extractant has a structure as shown in the following formula: R is selected from-CnH2n + 1, and n is equal to 2-18. In the extraction process, Lewis acid does not need to be added for synergistic extraction; the requirement on the acid concentration in the back extraction process is reduced, so that the risk that extraction equipment is corroded is reduced; meanwhile, sodium ions can be removed through water washing, so that the extraction rate is high, the operation steps are simple, and the method has industrial application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium extraction, and particularly relates to an amide extraction system for extracting lithium under alkaline conditions and a method thereof. BACKGROUND

[0002] Lithium resources are the core elements of the new energy revolution and play a crucial role in today's energy transformation and high-tech development. From the perspective of energy, lithium is a key material for power batteries (such as ternary lithium and lithium iron phosphate batteries), which are widely used in electric vehicles and energy storage systems, driving the global energy structure towards clean transformation. In addition to batteries, lithium is also used in aerospace, nuclear industry and high-end electronic equipment manufacturing, and is an indispensable raw material for high-tech industries.

[0003] The rapid growth of the electric vehicle market has driven the rapid growth of lithium demand. In 2022, global lithium demand was about 700,000 tons of lithium carbonate equivalent (LCE), and it is expected to exceed 3 million tons by 2030, with an annual growth rate of over 20%.

[0004] The distribution of global lithium resources presents a centralized feature, with more than 50% of global reserves concentrated in the "lithium triangle" region of South America. Hard rock type lithium mines (lithium spodumene, lithium mica) are mainly distributed in Sichuan, Jiangxi and other places, but the ore grade is generally lower than that of high-quality lithium mines in Australia, Chile and other countries. High magnesium-lithium ratio salt lakes (such as the Chai'erhan Salt Lake in Qinghai with a magnesium-lithium ratio of 500:1) require complex processes such as adsorption and membrane separation, with low technical maturity and high energy consumption.

[0005] Solvent extraction method for extracting lithium is a high efficiency, good selectivity, environmental adaptability of lithium element separation method, by selecting the appropriate extraction agent, optimization process conditions, can further improve the extraction efficiency and purity of lithium, to meet the global demand for lithium resources development. Patent (invention patent: a kind of extraction composition, extraction system and its application, application number: 201610383061.X, application date: 2016.06.01) discloses a kind of mixed extraction system consisting of N,N-dihexyl-2-methylpropionamide and N,N-di (2-ethylhexyl) acetamide and neutral phosphorus oxygen compound, the extraction rate of lithium-containing brine is more than 80%, lithium magnesium distribution coefficient is as high as 600 or more, with hydrochloric acid stripping, stripping rate is more than 85%. Patent (invention patent: application of amide compounds, extraction composition containing and extraction system, application number: 201610560045.3, application date: 2016.07.15) discloses a kind of mixed extraction system consisting of N,N-di (2-ethylhexyl) -2-methoxy acetamide and neutral phosphorus oxide, which can extract and strip lithium from lithium-containing brine, the extraction rate of lithium in lithium-containing brine is 81.41%, and the lithium-magnesium distribution coefficient is as high as 254 or more. When stripping lithium with hydrochloric acid, the stripping rate is more than 92.19%. Patent (invention patent: a kind of extraction composition, extraction system, extraction method and stripping method, application number: 201610381863.7, application date: 2016.06.01) discloses a kind of mixed extraction system consisting of N,N-di (2-ethylhexyl) acetamide and N,N-dihexyl p-methyl benzamide and neutral phosphorus oxide compound. The system has good acid-base stability, low water solubility and relatively simple operation, and is suitable for industrial promotion. The extraction system composed of these amide extractants needs to add strong Lewis acid such as FeCl3 as co-extraction agent during extraction process. Strong acid conditions must be maintained during extraction to prevent FeCl3 hydrolysis, so it is suitable for lithium extraction under acidic conditions, which increases the corrosion efficiency of extraction equipment. When traditional amide extractants are used for lithium extraction, strong Lewis acid such as FeCl3 needs to be added as co-extraction agent in the mixed extraction system. On the one hand, the composition of the extraction system is complex, which increases the investment of basic cost. On the other hand, Lewis acid is easy to hydrolyze. In order to prevent hydrolysis, strong acid environment must be maintained during extraction, which increases the cost and accelerates the corrosion rate of extraction equipment. SUMMARY

[0006] The main purpose of the present application is to provide an amide extraction system and method for extracting lithium under alkaline conditions to overcome the shortcomings of the prior art.

[0007] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include:

[0008] The embodiment of the present application provides an amide extraction system for extracting lithium under alkaline conditions, the amide extraction system comprising an amide extractant, a synergistic extractant and a diluent; wherein the extractant is an amide extractant having a structure as shown in formula (I):

[0009]

[0010] wherein R is selected from -C n H 2n+1 , and n=2-18.

[0011] The embodiment of the present application also provides application of the aforementioned amide extraction system for extracting lithium under alkaline conditions in lithium extraction.

[0012] The embodiment of the present application also provides a method for extracting lithium from an alkaline lithium-containing solution, comprising:

[0013] providing the aforementioned amide extraction system for extracting lithium under alkaline conditions;

[0014] and mixing the amide extraction system with an extracted aqueous phase to perform extraction, water washing and stripping treatment, so as to realize separation and enrichment of lithium; wherein the extracted aqueous phase is an alkaline lithium-containing solution.

[0015] Compared with the prior art, the present application has the beneficial effects that: the present application provides a method for extracting lithium in an alkaline solution by using the aforementioned extraction system; compared with the prior art, the method has the following advantages: first, in the extraction process, there is no need to add Lewis acid for synergistic extraction; in the stripping process, the requirement for acid concentration is reduced, thereby reducing the risk of corrosion of the extraction equipment; second, sodium ions can be removed by water washing, which not only has high extraction rate, but also has simple operation steps, and has more industrial application potential. DETAILED DESCRIPTION

[0016] In view of the defects of the prior art, the present application discloses an amide extraction system for extracting lithium from an alkaline lithium-containing solution. The system comprises an extractant, a synergistic extractant and a diluent. The extractant is an alkyl-substituted ortho-hydroxybenzamide compound; the synergistic extractant is trialkyl phosphine oxide (TRPO), tri-n-octyl phosphine oxide (TOPO), tributyl phosphate (TBP), di(2-ethylhexyl)phosphoric acid ester (P204) and N,N-bis(1-methylheptyl)acetamide (N523); and the diluent is sulfonated kerosene, o-dichlorobenzene, toluene and the like. The system extracts lithium in an alkaline solution, and sodium ions can be removed by water washing, so as to realize separation of lithium and sodium. The system has low requirements for alkalinity and acidity in the extraction process, high lithium ion extraction rate, simple steps, effectively shortened process procedure, saved cost and improved practical value.

[0017] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0018] Specifically, as one aspect of the technical solutions of the present application, the amide extraction system for extracting lithium under alkaline conditions comprises an amide extractant, a synergistic extractant and a diluent; wherein the amide extractant has a structure as shown in formula (I):

[0019]

[0020] wherein R is selected from -C n H 2n+1 , and n=2-18.

[0021] In some preferred embodiments, the synergistic extractant comprises any one or a combination of more than one of trialkylphosphine oxide (TRPO), tri-n-octylphosphine oxide (TOPO), tributylphosphate (TBP), di(2-ethylhexyl)phosphate (P204), and N,N-bis(1-methylheptyl)acetamide (N523), and is not limited thereto.

[0022] Further, the synergistic extractant is trialkylphosphine oxide (TRPO).

[0023] In some preferred embodiments, the diluent comprises any one or a combination of more than one of sulfonated kerosene, o-dichlorobenzene, toluene, dichloromethane, 1,2-dichloroethane / chloroform, ethyl acetate, and cyclohexane, and is not limited thereto.

[0024] Further, the diluent is cyclohexane.

[0025] In some preferred embodiments, the molar ratio of the amide extractant to the synergistic extractant in the amide extraction system is 5:1-1:100.

[0026] In some preferred embodiments, the total concentration of the amide extractant and the synergistic extractant in the amide extraction system is 0.05-2.4 mol / L.

[0027] The present application discloses an extraction system composed of an amide extractant and trialkylphosphine oxide (TRPO), which does not need to add Lewis acid co-extraction, is suitable for extracting lithium in alkaline solution system, has simple organic phase composition, simple operation, small amount of stripping acid, low cost, small corrosion to extraction equipment, and has industrial application prospect.

[0028] The structure of the extractant in the present application is shown in formula (I), and the basic skeleton is ortho-hydroxybenzamide, and R is a substituent modifying the basic skeleton of ortho-hydroxybenzamide;

[0029]

[0030] Further, R is an alkyl group (-C n H 2n+1 , n = 1, 2, 3, 4, …), preferably n = 12.

[0031] Another aspect of the embodiment of the present application also provides the use of the aforementioned amide-based extraction system for extracting lithium under alkaline conditions, preferably in alkaline solution.

[0032] Another aspect of the embodiment of the present application also provides a method for extracting lithium from an alkaline lithium-containing solution, comprising:

[0033] providing the aforementioned amide-based extraction system for extracting lithium under alkaline conditions;

[0034] and mixing the amide-based extraction system with the extracted aqueous phase to perform extraction, water washing, and back extraction, so as to realize the separation and enrichment of lithium; wherein the extracted aqueous phase is an alkaline lithium-containing solution.

[0035] In some preferred embodiments, the concentration of Li + in the extracted aqueous phase is 0.05 mol / L-0.50 mol / L;

[0036] In some preferred embodiments, the concentration of Na + in the extracted aqueous phase is 0.01 mol / L-2.0 mol / L.

[0037] In some preferred embodiments, the concentration of K + in the extracted aqueous phase is 0.01 mol / L-4.0 mol / L.

[0038] In some preferred embodiments, the concentration of OH - in the extracted aqueous phase is 0.01 mol / L-3.0 mol / L.

[0039] In some preferred embodiments, the anions in the extracted aqueous phase include any one or a combination of OH - , Cl - , CO3 2- , SO4 2- , NO3 - , and the like, without being limited thereto.

[0040] In some preferred embodiments, the method specifically comprises:

[0041] The extraction system is mixed with the extracted water phase and extracted at 10-70℃, and the loaded organic phase and the raffinate are obtained by phase separation;

[0042] Further, the water washing treatment includes washing the loaded organic phase with water, and the volume ratio of the loaded organic phase to water is 1:5-5:1.

[0043] Further, the volume ratio of the extraction system to the extracted water phase is 1:5-5:1.

[0044] Further, the volume ratio of the loaded organic phase to water in the water washing treatment is 1:5-5:1.

[0045] Further, the volume ratio of the loaded organic phase to water in the water washing treatment is 1:5-5:1.

[0046] Further, the extraction includes any one or a combination of single-stage oscillation extraction, multi-stage countercurrent extraction, and multi-stage cross-flow extraction, and is not limited thereto.

[0047] Further, the extraction time is 2-20 min.

[0048] Further, the acid includes any one or a combination of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, carbonic acid, acetic acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and oxalic acid, and is not limited thereto.

[0049] Further, the acid has H + The concentration is 0.01 mol / L-0.5 mol / L.

[0050] The extraction method provided by the application includes preparing the above-mentioned extraction system organic phase and the extracted water phase in a certain proportion, mixing them in a certain proportion, oscillating for 10 min, reaching equilibrium, and standing to separate the phases to obtain the loaded organic phase and the raffinate. The loaded organic phase is washed with water in a certain phase ratio to remove sodium impurities. The obtained loaded organic phase is back-extracted with a low-concentration acid in a certain phase ratio to obtain a lithium-rich aqueous solution and an empty-loaded mixed organic phase.

[0051] Further, the mass transfer process of the above-mentioned extraction is realized by a shaker, and should also include a centrifugal extractor, a tower extractor, and a mixing and clarifying tank.

[0052] The application provides an extraction system for extracting lithium from an alkaline lithium-containing solution, and the key points are the structure of the extractant, the structure of the synergistic agent, the composition of the diluent, and the composition of the extraction system. The application also provides a method for extracting lithium from an alkaline solution by using the above-mentioned extraction system, and the key point is direct extraction under alkaline conditions without the need for prior saponification, water washing to remove sodium, and acid back-extraction for enrichment.

[0053] The technical solutions of the present application will be further described in detail below in combination with several preferred embodiments. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0054] The experimental materials used in the following examples are commercially available from conventional biochemical reagent companies, unless otherwise specified.

[0055] Example 1

[0056] Preparation of the organic phase for extraction: N-pentyl-o-hydroxybenzamide is mixed with trialkyl phosphine oxide (TRPO) at a molar ratio of 1 / 1, and cyclohexane is used as a diluent to prepare an organic phase with a concentration of 1.0 mol / L of N-pentyl-o-hydroxybenzamide;

[0057] The aqueous phase to be extracted: Li + with a concentration of 0.3 mol / L, Na + with a concentration of 1.0 mol / L, OH- with a concentration of 1.0 mol / L, and Cl - with a concentration of 0.3 mol / L;

[0058] Extraction: the organic phase is mixed with the aqueous phase to be extracted at a ratio of V O / V A = 1 / 1, shaken for 10 min at 25°C, and after reaching equilibrium, the phases are separated by standing, and the loaded organic phase and the raffinate are obtained. The lithium ion extraction rate is calculated from the raffinate to be 60.0%;

[0059] Water washing to remove sodium: the loaded organic phase obtained in the previous step is mixed with distilled water at a ratio of V O / V A = 2 / 1, shaken for 10 min, and after reaching equilibrium, the phases are separated by standing, and the lithium-loaded organic phase is obtained. The sodium ion elution rate is 90.6%;

[0060] Stripping step: the lithium-loaded organic phase obtained in the previous step is mixed with 0.2 mol / L hydrochloric acid at a ratio of V O / V A = 1 / 1, shaken for 10 min, and after reaching equilibrium, the phases are separated by standing, and a lithium-rich solution and an empty organic phase are obtained. The stripping rate is 95.1%, and the total lithium yield is 57.1%.

[0061] Example 2

[0062] Compared with Example 1, in Example 2, the extractant is changed to N-isooctyl-o-hydroxybenzamide, the concentration of Na 、 in the aqueous phase to be extracted is changed to 1.5 mol / L, the concentration of hydrochloric acid in the stripping step is 0.3 mol / L, there is no water washing step to remove sodium, and the other conditions remain unchanged.

[0063] The extraction rate of lithium ion in the extraction step was 61.9%;

[0064] The stripping rate in the stripping step was 92.2%, and the total yield of lithium was 57.1%.

[0065] Example 3

[0066] Compared with Example 1, in Example 3, the extractant was changed to N-n-octyl salicyl amide, the diluent was changed to o-dichlorobenzene, the organic phase concentration was changed to 1.2 mol / L, there was no water washing and sodium removal step, and the rest of the conditions were unchanged.

[0067] The extraction rate of lithium ion in the extraction step was 68.2%;

[0068] The stripping rate in the stripping step was 92.6%, and the total yield of lithium was 63.2%.

[0069] Example 4

[0070] Compared with Example 1, in Example 4, the extractant was changed to N-n-octyl salicyl amide, the synergist was changed to TBP, there was no washing and sodium removal step, and the rest of the conditions were unchanged.

[0071] The extraction rate of lithium ion in the extraction step was 48.0%;

[0072] The stripping rate in the stripping step was 90.7%, and the total yield of lithium was 43.5%.

[0073] Example 5

[0074] Preparation of the extraction organic phase: N-dodecyl salicyl amide and trialkyl phosphine oxide (TRPO) were mixed in a molar ratio of 1 / 1, cyclohexane was used as a diluent, and an organic phase with a concentration of 1.0 mol / L of N-pentyl salicyl amide was prepared;

[0075] The extracted aqueous phase: Li + The concentration was: 0.3 mol / L, Na + The concentration was: 1.0 mol / L, OH- concentration was: 1.0 mol / L, Cl - The concentration was 0.3 mol / L;

[0076] Extraction: the organic phase and the extracted aqueous phase were mixed in a V O / V A = 1 / 1 ratio, shaken for 10 min at 25°C, and after equilibrium, the phases were separated, and the loaded organic phase and the raffinate were obtained, respectively. The extraction rate of lithium ion was calculated by the raffinate to be 71.6%;

[0077] Water washing and sodium removal: the loaded organic phase obtained in the previous step was mixed with distilled water in a V O / V A= 2 / 1 ratio mixing, shaking for 10 min, after reaching equilibrium, standing to separate phases, obtaining lithium-loaded organic phase, sodium ion elution rate 91.5%;

[0078] Strip step: the lithium-loaded organic phase obtained in the previous step was mixed with 0.2 mol / L hydrochloric acid at V O / V A = 1 / 1 mixing, shaking for 10 min, after reaching equilibrium, standing to separate phases, obtaining lithium-rich solution and empty organic phase, stripping rate 94.6%, total lithium yield 67.7%.

[0079] Example 6

[0080] Compared with Example 5, in Example 6, the molar mixing ratio of the extractant N-dodecyl salicyl amide and the synergistic extractant TRPO was changed to 1 / 3, the sodium removal step was removed, and the other conditions remained unchanged.

[0081] The lithium ion extraction rate in the extraction step was 54.9%;

[0082] The stripping rate in the stripping step was 92.4%, and the total lithium yield was 50.7%.

[0083] Example 7

[0084] Compared with Example 5, in Example 7, the total concentration of the extractant N-dodecyl salicyl amide and the synergistic extractant TRPO was changed to 2.4 mol / L, Li + concentration was changed to 0.4 mol / L, OH - concentration was changed to 0.4 mol / L, and the sodium removal step was removed, and the other conditions remained unchanged.

[0085] The lithium ion extraction rate in the extraction step was 78.8%;

[0086] The stripping rate in the stripping step was 91.2%, and the total yield was 71.9%.

[0087] Example 8

[0088] Compared with Example 5, in Example 8, the total concentration of the extractant and the synergistic extractant was changed to 0.8 mol / L, Li + concentration was changed to 0.1 mol / L, OH - concentration was changed to 0.5 mol / L, K + concentration was 0.5 mol / L, Cl - concentration was changed to 0.1 mol / L, and the sodium removal step was removed, and the other conditions remained unchanged.

[0089] The lithium ion extraction rate in the extraction step was 77.7%;

[0090] The stripping rate in the stripping step was 92.1%, and the total yield was 71.6%.

[0091] Example 9

[0092] Compared with Example 5, in Example 9, the total concentration of extractant and synergist is changed to 0.8 mol / L, the concentration of OH is changed to 1.5 mol / L, the concentration of Na + is changed to 1.5 mol / L, the concentration of Li + is changed to 0.1 mol / L, the concentration of Cl - is changed to 0.1 mol / L, there is no water washing step to remove sodium, and the rest of the conditions remain unchanged.

[0093] The extraction rate of lithium ions in the extraction step is 59.4%;

[0094] The stripping rate in the stripping step is 90.2%, and the total yield is 53.6%.

[0095] Example 10

[0096] Compared with Example 9, in Example 10, the concentration of OH - is changed to 0.5 mol / L, the concentration of Na + is changed to 0.5 mol / L, the concentration of Li + is changed to 0.4 mol / L, the concentration of Cl - is changed to 0.4 mol / L, there is no water washing step to remove sodium, and the rest of the conditions remain unchanged.

[0097] The extraction rate of lithium ions in the extraction step is 30.7%;

[0098] The stripping rate in the stripping step is 89.9%, and the total yield is 27.6%.

[0099] Example 11

[0100] Compared with Example 10, in Example 11, the concentration of Li + is changed to 0.1 mol / L, the concentration of Cl - is changed to 0.1 mol / L, the extraction phase ratio (V O / V A ) is changed to 4 / 1, there is no water washing step to remove sodium, and the rest of the conditions remain unchanged.

[0101] The extraction rate of lithium ions in the extraction step is 97.1%;

[0102] The stripping rate in the stripping step is 91.6%, and the total yield is 88.9%.

[0103] Example 12

[0104] Compared with Example 10, in Example 12, the concentration of Li + is changed to 0.1 mol / L, the concentration of Cl -The concentration was changed to 0.1 mol / L, the extraction time was changed to 15 min, there was no water washing step to remove sodium, and the other conditions remained unchanged.

[0105] The extraction rate of lithium ions in the extraction step was 74.4%.

[0106] The stripping rate in the stripping step was 88.7%, and the total yield was 66.0%.

[0107] Example 13

[0108] In Example 13, compared with Example 10, Li + The concentration was changed to 0.1 mol / L, Cl - The concentration was changed to 0.1 mol / L, the extraction temperature was changed to 60°C, there was no water washing step to remove sodium, and the other conditions remained unchanged.

[0109] The extraction rate of lithium ions in the extraction step was 59.5%.

[0110] The stripping rate in the stripping step was 89.5%, and the total yield was 53.3%.

[0111] Example 14

[0112] In Example 14, compared with Example 10, Li + The concentration was changed to 0.1 mol / L, Cl - The concentration was changed to 0.1 mol / L, the extraction process was changed to four-stage countercurrent extraction, there was no water washing step to remove sodium, and the other conditions remained unchanged.

[0113] The extraction rate of lithium ions in the extraction step was 98.8%.

[0114] The stripping rate in the stripping step was 93.1%, and the total yield was 91.9%.

[0115] Example 15

[0116] In Example 15, compared with Example 10, Li + The concentration was changed to 0.1 mol / L, Cl - The concentration was changed to 0.1 mol / L, SO4 2- The concentration was 0.4 mol / L, Na + The concentration was changed to 1.3 mol / L, the extraction process was changed to four-stage countercurrent extraction, there was no water washing step to remove sodium, and the other conditions remained unchanged.

[0117] The extraction rate of lithium ions in the extraction step was 98.8%.

[0118] The stripping rate in the stripping step was 93.1%, and the total yield was 91.9%.

[0119] Example 16

[0120] Compared with Example 10, in Example 16, the concentrations of the extractant and the co-extractant in the organic phase are changed to 0.6 mol / L, and the aqueous phase composition is prepared by adding NaOH to a lithium precipitation mother liquor (part of the cationic components of which are shown in Table 1). A water washing step is added, and the water washing ratio is V O / V A = 4 / 1, and the oscillation time is 10 min. The other conditions remain unchanged.

[0121] Table 1 Cationic composition of lithium precipitation mother liquor

[0122] ions Li + ]]> Na + ]] K + ]]> Ca 2+ ]]> Mg 2+ ]]> pH Concentration / mol*L -1 ]] 0.395 2.07 0.017 6.1*10 -5 ]]> 3.08*10 -5 ]]> 11.5

[0123] The lithium ion extraction rate in the extraction step is 72.1%;

[0124] The sodium ion elution rate in the water washing step is 90.0%;

[0125] The stripping rate in the stripping step is 94.8%, and the total yield of lithium is 68.4%.

[0126] Comparative Example 1

[0127] Compared with Example 1, in Comparative Example 1, no extractant is added in the organic phase, and the other conditions remain unchanged.

[0128] The lithium ion extraction rate in the extraction step is only 2.3%.

[0129] The lithium ion extraction rate is too low, and the water washing and stripping steps have no practical significance.

[0130] Comparative Example 2

[0131] Compared with Example 1, in Comparative Example 2, the co-extractant is changed to N523, and the other conditions remain unchanged.

[0132] The lithium ion extraction rate in the extraction step is 36.5%, the sodium ion elution rate in the water washing step is 40.53%, the stripping rate in the stripping step is 70.1%, and the total yield of lithium is 25.6%.

[0133] Comparative Example 3

[0134] Compared with Example 1, in Comparative Example 3, the extractant is changed to N-pentylbenzamide, and the other conditions remain unchanged.

[0135] In the extraction step, the lithium ion extraction rate is only 1.6%, and the subsequent water washing and stripping steps have no practical significance.

[0136] In addition, the inventors of the present application have also carried out tests with other raw materials, process operations and process conditions described in the present specification with reference to the foregoing examples, and all ideal results have been obtained.

[0137] It should be understood that the technical solutions of the present application are not limited to the above specific implementation cases, and any technical modification made according to the technical solutions of the present application without departing from the purpose of the present application and the scope protected by the claims falls within the protection scope of the present application.

Claims

1. An amide-based extraction system for lithium recovery under alkaline conditions, characterized in that: The amide extraction system comprises an amide extractant, a synergist and a diluent; wherein the amide extractant has a structure as shown in formula (I): wherein R is selected from -C n H 2n+1 , n = 2-18.

2. The amide-based extraction system of claim 1, wherein: The synergist comprises a combination of any one or more of trialkyl phosphine oxide, tri-n-octyl phosphine oxide, tributyl phosphate, di(2-ethylhexyl)phosphate, N,N-bis(1-methylheptyl)acetamide, preferably trialkyl phosphine oxide.

3. The amide-based extraction system of claim 1, wherein: The diluent comprises a combination of any one or more of sulfonated kerosene, o-dichlorobenzene, toluene, dichloromethane, 1,2-dichloroethane / chloroform, ethyl acetate, cyclohexane, preferably cyclohexane.

4. The amide-based extraction system of claim 1, wherein: The molar ratio of the amide extractant to the synergist in the amide extraction system is 5:1-1:100; And / or, the total concentration of the amide extractant and the synergist in the amide extraction system is 0.05 mol / L-2.4 mol / L.

5. The use of the amide extraction system for lithium extraction under alkaline conditions according to any one of claims 1-4, preferably the use of the amide extraction system for lithium extraction in an alkaline solution.

6. A method of extracting lithium from an alkaline lithium-containing solution, characterized in that, Comprising: providing the amide extraction system for lithium extraction under alkaline conditions according to any one of claims 1-4; and mixing the amide extraction system with an extracted aqueous phase to perform extraction, water washing and stripping treatment, thereby realizing the separation and enrichment of lithium; wherein the extracted aqueous phase is an alkaline lithium-containing solution.

7. The method of claim 6, wherein, Specifically comprising: mixing the extraction system with the extracted aqueous phase and performing extraction at 10-70°C to obtain a loaded organic phase and a raffinate through phase separation; and using water to wash the loaded organic phase, and then using an acid to strip the obtained loaded organic phase to obtain a lithium-rich solution.

8. The method of claim 6, wherein: The concentration of Li+ in the extracted aqueous phase is 0.05 mol / L-0.50 mol / L; And / or, the concentration of Na in the water phase is 0.01 mol / L-2.0 mol / L. + And / or, the concentration of Na in the water phase is 0.01 mol / L-2.0 mol / L. And / or, the concentration of K in the water phase is 0.01 mol / L-4.0 mol / L. + And / or, the concentration of K in the water phase is 0.01 mol / L-4.0 mol / L. And / or, the concentration of OH- in the extracted aqueous phase is 0.01 mol / L-3.0 mol / L; and / or the anions in the water phase to be extracted comprise any one or more of a combination of OH - , Cl - , CO3 2- , SO4 2- , NO3 - .

9. The method of claim 7, wherein: The volume ratio of the extraction system to the extracted aqueous phase is 1:5-5:1; And / or, the volume ratio of the loaded organic phase to water in the water washing treatment is 1:5-5:1; And / or, the volume ratio of the loaded organic phase in the stripping treatment is 2:1-1:

10.

10. The method of claim 7, wherein: The extraction comprises a combination of any one or more of single-stage oscillation extraction, multi-stage countercurrent extraction and multi-stage crossflow extraction; And / or, the extraction time is 2-20 min; And / or, the acid comprises a combination of any one or more of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, carbonic acid, acetic acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid and oxalic acid. and / or, H in the acid + concentration is 0.01-0.5 mol / L.

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