Hydrophobic organic liquid composition for selective extraction of lithium salts

Abstract

The invention relates to a hydrophobic organic liquid composition for the selective extraction of diionic lithium salts comprising lithium cations and anions, in particular selected from the group consisting of Cl-, I-, Br-, CN-, NO3-, HCO3-, complementary to the lithium cations, from lithium-rich brine to be treated, said composition comprising: (A) at least one lithium cation extraction compound, compounds selected from the following formula: wherein R1, R2, R3, R4, R5, R6 are defined as described below; (B) at least one hydrophobic protic organic compound for solvating an anion complementary to the lithium cation; and (C) at least one hydrophobic polar organic diluent having a flash point at atmospheric pressure of greater than 60 DEG C, preferably greater than 75 DEG C, more preferably greater than 90 DEG C.

Description

Technical Field

[0001] The present invention relates to a hydrophobic organic liquid composition for selectively extracting lithium salts. Background Art

[0002] As part of the energy transition, the global goal is to replace conventional vehicles, which account for 20% of global CO2 emissions, with electric vehicles. This means that global production of metals such as lithium, nickel, cobalt, copper, and manganese must increase several-fold. In particular, lithium, a key material in lithium-ion batteries, must see its production increase fourfold from 990,000 tons of lithium carbonate equivalent (LCE) in 2020 to 3.7 million tons of LCE in 2030 to support the sixteen-fold increase in electric vehicle manufacturing demand and provide raw materials for over 300 new battery factory projects.

[0003] Due to the supply-demand imbalance caused by the surge in demand, lithium prices have climbed from US$16,750 per ton of lithium carbonate equivalent in 2018 to US$71,750 per ton of lithium carbonate equivalent in 2022. Given that lithium mine production capacity is unable to keep up with the growth rate of demand, this supply-demand gap is unlikely to be alleviated in the short term.

[0004] Although lithium is widely present on Earth, in the form of mineral rocks (spodumene, lepidolite, petalite, etc.) and salts soluble or insoluble in water (LiCl, Li2SO4, etc.), its mining volume (186,000 tons of lithium) is still limited compared to other metals involved in the energy transition - the latter are all measured in millions of tons (iron: 1.5 billion tons; aluminum: 65 million tons; copper: 20 million tons; manganese: 19 million tons; zinc: 12 million tons; chromium: 12 million tons; titanium: 8 million tons; lead: 4.7 million tons; nickel: 4.7 million tons).

[0005] In particular, lithium-rich brines are usually collected from continental brines, oil-produced brine, geothermal brine and other types of brines formed in natural environments such as the Andes Mountains or the endorheic basins of the Qinghai-Tibet Plateau.

[0006] In existing applications, for high-concentration lithium chloride salt mines, the salt field evaporation method is usually used to evaporate the water from the brine extracted from the underground, so that the lithium concentration is concentrated from 200-2000 mg / L to more than 50g / L, and up to 80g / L. This stage needs to be carried out in evaporation ponds covering hundreds of hectares. Its construction period is as long as 3 to 4 years, and it requires continuous maintenance to prevent leakage. In addition, this natural evaporation process is completely dependent on sunlight and climatic conditions. It takes 12 to 24 months from brine extraction to concentration, resulting in fluctuations in production and quality. At the same time, millions of tons of crystalline salt (sodium chloride, sodium sulfate, potassium sulfate, potassium chloride, sodium magnesium sulfate, etc.) are generated, which need to be regularly removed to maintain the processing capacity of the evaporation and crystallization system.

[0007] After this initial stage, the resulting lithium concentrate contains all the ionic components of the original brine and needs to go through multiple downstream brine treatment processes to remove mineral impurities other than lithium in order to finally obtain the desired lithium, usually in the form of Li2CO3 after carbonate. After completing the solar evaporation pond treatment, it is usually necessary to connect multiple units in series to remove boron by liquid-liquid extraction, followed by chemical precipitation to remove calcium, magnesium and sulfate, and then pass through the ion exchange resin after treatment in the potassium chloride crystallizer and finally enter the carbonation terminal unit. This unit precipitates lithium carbonate Li2CO3 by adding sodium carbonate Na2CO3 at 80°C to achieve residual sodium ions Na + With lithium ion Li + Separation of:

[0008] LiCl (aqueous solution) + Na2CO3 (solid) => Li2CO3 (precipitate) + NaCl (aqueous solution).

[0009] The presence of sodium ions in concentrated lithium chloride brine makes it impossible to directly prepare battery-grade lithium hydroxide hydrate. Therefore, LiCl must first be carbonated to Li2CO3, then redissolved through secondary carbonation to obtain a sufficient level of Li2CO3, and then chemically converted to lithium hydroxide by electrolysis, or by adding Ca(OH)2:

[0010] Ca(OH)2(aqueous solution)+Li2CO3(solid)=>2LiOH(aqueous solution)+CaCO3(precipitate).

[0011] The direct conversion of LiCl into lithium hydroxide hydrate can reduce the operating cost (OPEX) of lithium hydroxide hydrate by at least US$2,500 per ton, thereby significantly improving the market competitiveness of the process.

[0012] To meet the strong demand for lithium resources, this production method must simultaneously improve production efficiency, lithium recovery rate, product purity and optimize costs, while achieving excellent environmental, social and governance (ESG) performance.

[0013] For example, producing countries, led by Chile, have imposed increasingly stringent restrictions on the maintenance of solar evaporation ponds due to the high water consumption caused by brine evaporation, a process that is considered unsustainable in the extremely arid Andean highlands, where annual rainfall is only 15 to 100 mm.

[0014] Other historical issues with lithium production from brines are known in China, Bolivia, and, to a lesser extent, Argentina, due to excess magnesium and / or sulfate in the brine composition. When the magnesium-to-lithium mass ratio exceeds 6, lithium tends to co-precipitate with magnesium (e.g., carnallite (MgCl2·KCl·6H2O), bischofite (MgCl2·6H2O), and lithium carnallite (LiCl·MgCl2·7H2O)) due to their similar physicochemical properties, making separation difficult. In China, for example, in the Qinghai-Tibet Plateau, magnesium-to-lithium ratios of 10-40, and even as high as 100, are common. Furthermore, under sulfate enrichment conditions, other salt combinations can combine with lithium and result in lithium loss due to co-precipitation (precipitation of sodium kainite (Na2Mg(SO4)2·4H2O), kainite (K2Mg(SO4)2·6H2O), kainite (K2Mg(SO4)2·4H2O), kainite (MgSO4·KCl·3H2O), and epsomite (MgSO4·7H2O). This solar concentration process can result in lithium losses exceeding 40% to 70% due to co-precipitation and loss of lithium-rich brines. This high lithium loss in some brines makes the process economically and environmentally unfeasible.

[0015] Lithium in brine accounts for about 75%-80% of the world's total lithium resources, significantly ahead of pegmatite-type lithium mines.

[0016] The present invention aims to address the aforementioned technical challenges by providing a solution for selectively extracting lithium chloride from brine in the presence of multiple salts, particularly sodium chloride, potassium chloride, calcium chloride, magnesium chloride, strontium chloride, sodium sulfate, potassium sulfate, sodium hydrogen borate, and potassium hydrogen borate. Compared to treating all impurities in the brine, which constitute the majority, the present invention focuses on extracting only the target salt, in this case lithium chloride, thereby significantly improving the technical and economic parameters shown in Table 1.

[0017] [Table 1]

[0018]

[0019] To this end, the present invention proposes a liquid-liquid extraction solution that achieves the selective extraction of diionic lithium salts (salts containing a monoanion and a monovalent cation) from a variety of coexisting dissolved inorganic compounds (at least selected from alkali metals, alkaline earth metals, halogens, sulfates, carbonates and other borates) through a specific organic formula.

[0020] The selective extraction of lithium from natural or artificial brines using liquid-liquid extraction has been studied for many years.

[0021] For example, US Pat. No. 3,306,712 discloses a method for selectively extracting lithium chloride, lithium bromide or lithium iodide from calcium chloride brine using alcohol or ketone solvents, and regenerating the solvent by adding an aqueous solution of urea to remove the co-extracted calcium chloride.

[0022] Gabra and Torma[1] studied the extraction performance of various alcohols for lithium chloride, sodium chloride, potassium chloride, and calcium chloride, and found that the separation coefficients for (Li, Na), (Li, K), and (Li, Ca) were less than 3.21, 2.9, and 9.17, respectively. Although n-butanol had a high co-extraction rate for calcium chloride, it was still the best performing alcohol extractant. In general, the solubility of lithium chloride increases with decreasing molar mass of the alcohol, but increasing the molar mass is required to reduce the solubility of alkaline earth metal chlorides, magnesium chloride, and calcium chloride.

[0023] Bukowsky and Uhlemann[2] proposed the use of a mixed solvent system consisting of isoamyl alcohol and 2-ethyl-1,3-hexanediol, diisopropyl ether or diethyl ether. Although this solution can significantly inhibit the co-extraction of alkaline earth metal chlorides, it leads to a decrease in the extraction rate of lithium chloride and the solubility of the final product in the aqueous phase is too high.

[0024] US Patent No. 3,793,433 proposed to extract lithium by using a benzene solution of halogenated β-diketone and trioctylphosphine oxide (TOPO), and regenerating it with 0.15N hydrochloric acid. + , K + , Rb + 、Cs + ) exceeds 1000, but for alkaline earth metals (Mg 2+ , Ca 2+ ) has a much better extraction selectivity than lithium (SF<0.07), which makes it impossible to achieve the selective extraction of lithium from natural brine containing alkaline earth metals.

[0025] The use of acidic extractants such as 2-ethylhexylphosphonic acid (D2EHPA) faces the same technical obstacles, as experimental data show that although the lithium-D2EPHA complex has a high selectivity for other monovalent metal ions, and the addition of tributyl phosphate (TBP) can produce a synergistic effect to improve the lithium extraction rate, the extraction selectivity of such acidic extractants for alkaline earth metals is still significantly better than that for alkali metals ([3]). Therefore, commercial acidic extractants such as MEHPA, D2EHPA, Cyanex 272, PC88A, and Ionquest 801 are not suitable for the selective extraction of lithium in alkaline earth metal-containing systems.

[0026] Gao et al. [4] studied the synergistic extraction system of imidazole ionic liquids with carbon chain lengths of 4-9 and triisobutyl phosphate (TIBP). The study confirmed that [Li·2TIBP]+ The formation of organic phase complexes and the + / Li + Cation exchange enables acid regeneration, but the lithium extraction process relies on ionic liquids (C4 min + ) and Li + The cation exchange mechanism cannot maintain long-term extraction performance due to the continuous decomposition of ionic liquids.

[0027] Chinese patent CN106498184 proposes using N-methyl-N-(N'-2-ethylcarbonyl-ethylpyrrole) hexafluorophosphate as an ionic liquid, but does not disclose the specific process conditions for lithium chloride extraction and desorption.

[0028] Another research approach is to use a synergistic system of neutral organophosphorus extractants and co-extractants such as trivalent iron (Fe(III)). Among them, the TBP / methyl isobutyl ketone (MIBK) / ferric chloride system ([5]) is effective for Li + FeCl4 - The extraction capacity of ion pairs has attracted attention. A liquid-liquid extraction process based on this ternary lithium extraction has been evaluated ([6]). This process requires maintaining a high concentration of chloride ions (Cl) in the washing and stripping stages (1 ton HCl / ton LiCl). - and an acidic environment (to prevent Fe(OH)3 precipitation) to prevent the loss of hydrophilic Fe3+, which complicates the process. In addition, sodium hydroxide (2 tons of NaOH / ton of LiCl) is required to regenerate the system before extraction. As an alternative to TBP, other neutral extractants have also been studied, such as N,N-di(2-ethylhexyl)acetamide (N523) ([7]).

[0029] In order to avoid the use of trivalent iron, Zhou et al. ([8]) proposed to use sodium phosphomolybdate with a heteropolyacid structure as a co-extractant to form a synergistic system with TBP / MIBK. This technical solution achieves Na + / Li + Ion exchange, followed by washing with a 2MLiCl+NaCl (10 / 90) mixed solution to remove K by cation exchange + and Mg 2+ impurities. Next, a stripping stage uses 0.24M hydrochloric acid to produce an acidic lithium chloride solution. Finally, the organic phase must be neutralized with 0.26M sodium hydroxide to regenerate it before use. This novel cation exchange liquid-liquid extraction process, which involves four stages of extraction, cleaning, re-extraction, and regeneration, is theoretically feasible but requires precise control of the emission of potentially toxic molybdenum compounds and carries high chemical reagent costs.

[0030] U.S. Patent No. 2022 / 274956A1 proposes using a three-dimensional calixpyrrole structure to encapsulate salts, particularly lithium chloride, in the presence of sodium chloride and potassium chloride, suitable for solid-liquid and liquid-liquid extraction systems. However, the patent does not disclose the effect of the presence of alkali metals on the extraction process, making it unclear whether the method truly exhibits lithium selectivity.

[0031] Existing literature has not yet recorded a liquid-liquid extraction technology solution that can selectively extract lithium in the coexistence of alkali metals and alkaline earth metals, does not require the use of chemical reagents, and has short-term industrial feasibility (characteristics such as non-toxicity, low cost, and low water solubility). Summary of the Invention

[0032] The present invention relates to a hydrophobic organic liquid composition for selectively extracting a diionic lithium salt from lithium-rich brine to be treated, wherein the diionic lithium salt comprises a lithium cation and a complementary cation, particularly selected from Cl - , I - Br - 、CN - 、NO3 - 、HCO3 - anion, the composition comprising:

[0033] (A) at least one lithium cation extracting compound selected from the group consisting of:

[0034]

[0035] in:

[0036] - R1 and R2 may be the same or different, regardless of their position on the nitrogen atom, and are independently selected from a linear or branched C1-C 12 Alkyl, aryl, C4-C8 cycloalkyl; or

[0037] - R1 and R2, together with the nitrogen atom carrying them, form a five-membered, six-membered, seven-membered or eight-membered ring;

[0038] -R3 is selected from hydrogen, linear or branched C1-C8 alkyl, C4-C8 cycloalkyl, C2-C6 alkoxyalkyl and alkoxyalkylaryl;

[0039] -R4 is selected from hydrogen, linear or branched C1-C3 alkyl;

[0040] -R5 is selected from hydrogen, linear or branched C1-C3 alkyl;

[0041] -R6 is selected from hydrogen, linear or branched C1-C3 alkyl;

[0042] (B) at least one hydrophobic protic organic compound for solvating an anion complementary to the lithium cation; and

[0043] (C) at least one hydrophobic polar organic diluent having a flash point greater than 60°C, preferably greater than 75°C, more preferably greater than 90°C at atmospheric pressure.

[0044] The dual-ion lithium salt refers to a lithium salt comprising a single positively charged lithium cation Li + With single negatively charged monatomic or polyatomic anions, such as the monatomic anion Cl - or polyatomic anion NO3 - .

[0045] The molar mass of the lithium cation extracting compound may be at least 450 g / mol, preferably at least 550 g / mol.

[0046] The complexation constant Log K of the lithium cation extracting compound for the cation in methanol at 25°C may be at least 1, preferably greater than 2.

[0047] The lithium cation extraction compound may have a negative enthalpy change ΔH when complexing lithium cations, and at a temperature T=298K, the absolute value of the ratio of the enthalpy change ΔH of the complexed lithium cation to the entropy change ΔS of the complexed lithium cation |ΔH / (TΔS)| is greater than 2, preferably greater than 5.

[0048] The enthalpy and entropy changes during lithium cation complexation result in a free energy change, ΔG, that is primarily influenced by the enthalpy term rather than the entropy term. This provides a lithium cation extraction compound that can extract lithium ions at low temperatures and regenerate at high temperatures.

[0049] The melting point of the lithium cation extracting compound may be below 200°C, preferably below 50°C, more preferably below 25°C.

[0050] In a specific embodiment:

[0051] - R1 and R2, regardless of their position on the nitrogen atom, may be each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 2-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, 2-ethylhexyl, phenyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl; or

[0052] - R1 and R2, together with the nitrogen atom carrying them, form a pyrrolidine, piperidine, azepane or azacyclooctane ring;

[0053] -R3 can be selected from hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 2-methylbutyl, 2-ethylpropyl, n-hexyl, cyclohexyl, methoxymethyl, methoxyethyl, methoxypropyl, methoxybutyl and -CH2-O-CH2-phenyl; and

[0054] - R4, R5 and R6 may be hydrogen or methyl;

[0055] When the calcium concentration in the brine to be treated exceeds 10g / L and / or Li + / Ca 2+ Optionally, R1 and R2 are advantageously selected from butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl or phenyl; and

[0056] When the calcium concentration in the brine to be treated is lower than 10g / L and / or Li + / Na + When selective, R1 and R2 are advantageously selected from isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 2-ethylpropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, or R1 and R2 together with the nitrogen atom carrying them form a pyrrolidine, piperidine, azepane or azacyclooctane ring.

[0057] The lithium cation extracting compound may be selected from:

[0058]

[0059]

[0060]

[0061]

[0062] The hydrophobic protic organic compound for solvating anions complementary to lithium cations may have a pKa value in water at 25°C of at least 9, preferably at least 10.5, and preferably less than the pKa value of water at 25°C, or at least less than 15 at 25°C, and a solubility in water at 25°C of less than 0.01 mol / L.

[0063] The hydrophobic protic organic compound used to solvate the anion complementary to the lithium cation may be a compound of formula (B):

[0064]

[0065] in:

[0066] -R B 、R C and R DAt least one of the free radicals, which may be the same or different, is a halogen atom or an electron-withdrawing group selected from the group consisting of: F, Cl, Br; C m F 2m+1 , m≤4, m is a non-zero integer; CF2CF2C p H 2p+1 , p≤4, p is an integer; CF2C p H 2p+1 , p≤4, p is an integer; CH2C p F 2p+1 , p≤4, p is an integer; OCH2CF3; C(=O)CF3; C m H n F p Cl q Br s , m≤4, n, p, q, s are integers and at least one of p, q or s is not zero; C(=O)OC m H 2m+1 , m≤4, m is an integer; C(=O)C m H 2m+1 , m≤4, m is an integer;

[0067] -The rest of R A 、R B 、R C 、R D and R E Free radicals, which are the same or different, are selected from the following non-electron-withdrawing free radicals: H; CH3; CH2CH3; CH2CH2C p F 2p+1 , p≤4, p is an integer; C m H 2m-1 , m≤10, m is an integer greater than 1; C m H 2m+1 , m≤10, m is a non-zero integer; and R A to R E Only one free radical can be the latter two C m H 2m-1 or C m H 2m+1 One of the free radicals; and

[0068] -X is selected from the following radicals: .OH;

[0069]

[0070] where R A 、R B 、R C 、R D and R E They may be the same or different and are defined as in the above molecular formula (B);

[0071] R' and R", which may be the same or different, are selected from the following radicals: H; C n H 2n-1 , n≤4, n is an integer greater than 1; C n H 2n+1 , n≤4, n is a non-zero integer; CH2CH2C p F 2p+1 , p≤4, p is an integer; CH2C p F 2p+1 , p≤4, p is an integer; CF2C p H 2p+1 , p≤4, p is an integer; CF2CF2C p H 2p+1 , p≤4, p is an integer; C m F 2m+1 , m≤4, m is a non-zero integer; C m H n F p Cl q Br s , m≤4, n, p, q, s are integers and at least one of p, q or s is not zero;

[0072] R'' is selected from the following radicals: C m H 2m+1 , m≤20, m is an integer; C m H 2m-1 , m≤20, m is an integer greater than 1; C m H n F p Cl q Br s , m≤10, n, p, q, s are integers and at least one of p, q or s is not zero; CH2CH2C p F 2p+1 , p≤4, p is an integer; CH2C p F 2p+1 , p≤4, p is an integer; CF2C p H 2p+1 , p≤4, p is an integer; CF2CF2C p H 2p+1 , p≤4, p is an integer; C m F 2m+1 , m≤4, m is a non-zero integer; and an aryl radical of formula (b):

[0073]

[0074] where R A 、R B 、R C、R D and R E , which may be the same or different, are defined as the aforementioned molecular formula (B).

[0075] In particular, X in the compound of formula (B) can be represented by:

[0076]

[0077] Compound (B) can be represented by the following molecular formula:

[0078]

[0079] Wherein R'' is selected from the following radicals: C m H 2m+1 , m≤20, preferably ≤15, m is an integer; C m H 2m-1 , m≤20, m is an integer greater than 1; C m H n F p Cl q Br s , m≤10, n, p, q, s are integers and at least one of p, q or s is not zero; and an aryl radical of formula (b):

[0080]

[0081] where R A 、R B 、R C 、R D and R E They may be the same or different and are defined as the above-mentioned molecular formula (B).

[0082] In certain embodiments, the free radical R'' can be n-C7H 15 、Positive-C9H 19 、Positive-C 11 H 23 or positive-C 13 H 27 .

[0083] The concentration of the at least one lithium cation extracting compound in the composition may be from 0.15 to 1 mol / L, preferably from 0.3 to 1 mol / L, more preferably from 0.45 to 1 mol / L.

[0084] The molar concentration ratio of the at least one hydrophobic protic organic compound used to solvate anions complementary to the lithium cation to the at least one lithium cation extracting compound may be 1 to 10, preferably 1.5 to 5, more preferably 2 to 4.

[0085] The viscosity of the hydrophobic polar organic diluent at 20° C. may be less than 5 mPa·s, preferably less than 2 mPa·s.

[0086] Preferably, the hydrophobic polar organic diluent is an aromatic polar diluent, which can be selected from 2-chlorobromobenzene, 1,2-dibromobenzene, 2-bromotoluene or 3,4-dibromotoluene.

[0087] The hydrophobic organic liquid composition may have a density at 20°C greater than 1.20 kg / L, preferably greater than 1.25 kg / L, more preferably greater than 1.30 kg / L, and a viscosity at 20°C less than 50 mPa·s, preferably less than 25 mPa·s, and is used for treating brine with a density at 20°C that is at least 0.05 kg / L lower.

[0088] The hydrophobic organic liquid composition may have a density at 20°C greater than 1.25 kg / L, preferably greater than 1.30 kg / L, more preferably greater than 1.35 kg / L, and a viscosity at 20°C less than 30 mPa·s, preferably less than 15 mPa·s, and is used for treating brine with a density at 20°C that is at least 0.15 kg / L lower.

[0089] The viscosity of compositions of diluents and hydrophobic organic liquids is determined using an Anton Paar Lovis 2000 viscometer. The sample is injected into a capillary tube of known diameter. The measurement is performed by moving a steel ball through the capillary tube faster or slower depending on the viscosity of the sample. The instrument detects the ball at a specific angle and measures the time it takes to pass through the capillary tube. After precalibration with certified liquids, the device then provides viscosity measurements in mPa·s.

[0090] Density was measured using an Anton Paar DMA4100M electronic density meter in the temperature range of 0 to 100°C. The values ​​measured at 20°C are used as the reference. This device is described, for example, in patents EP3012612 and EP3101409.

[0091] The sample is injected into a precisely sized glass tube. The tube is vibrated. The period of the entire cycle (tube + liquid) is determined. The instrument subtracts this period from the baseline period of the empty tube to determine the period of the liquid inside the tube. Finally, the density of the liquid is determined based on a period-density relationship chart.

[0092] The present invention also relates to a compound selected from the following molecular formula:

[0093]

[0094]

[0095]

[0096] The present invention also relates to the use of the above-mentioned hydrophobic organic liquid composition in a lithium salt extraction process, which process includes: a step of mixing the hydrophobic organic liquid composition with brine to be treated at a first temperature, a step of separating the lithium salt-loaded hydrophobic organic liquid composition and the treated brine, and a step of regenerating the lithium salt-loaded hydrophobic organic liquid composition by treating the lithium salt-loaded hydrophobic organic liquid composition with treated water, wherein the regeneration step is carried out at a second temperature higher than the first temperature, and the temperature difference between the first temperature and the second temperature is 30 to 150°C, preferably 50 to 100°C, and more preferably 60 to 80°C.

[0097] One of the purposes of the present invention is to achieve the selective extraction of lithium chloride from lithium-rich continental brines in the Andean Plateau of Chile, Argentina, Bolivia and the Qinghai-Tibet Plateau of China. Figure 1 Approximately 20 natural brine compositions with an average density of 1.22 kg / L (in mmol / L) are shown. Among these compositions, Li / Na selectivity is the primary determining factor, followed by Mg / Li, Ca / Li, and SO₄ / Li selectivity. The compositions of the present invention are also suitable for treating these brines after reconcentration by solar evaporation or other methods.

[0098] Ion selective electrodes (ISEs) based on polyvinyl chloride (PVC) lithium ion selective membranes can be used to determine lithium concentrations in aqueous solutions or blood. In particular, Kamenica et al. ([9]) pointed out series I to VIII ionophores.

[0099]

[0100] Lithium ion carrier I: N,N'-diheptyl-N,N',5,5-tetramethyl-3,7-dioxanonane diamide, or 2,2'-[(2,2-dimethyl-1,3-propanediyl)bis(oxy)]bis[N-heptyl-N-methylacetamide], ETH 149, CAS N: 58821-96-8

[0101] Lithium ion carrier II: N,N,N',N'-tetraisobutyl-cis-cyclohexane-1,2-dicarboxamide, ETH 1644, CASN: 80547-18-8

[0102] Lithium ion carrier III: N,N-dicyclohexyl-N',N'-diisobutyl-cis-cyclohexane-1,2-dicarboxamide, ETH 1810, CAS N: 99281-50-2

[0103] Lithium ion carrier IV: N,N,N',N'-tetracyclohexyl-5-ethyl-5-butyl-3,7-dioxanonanediamide, or 2,2'-[(2-butyl-2-ethyl-1,3-propanediyl)bis(oxy)]bis[N,N-dicyclohexylacetamide], ETH 2137, CAS N: 108083-23-4

[0104] Lithium ion carrier V: 1,4,7,10-tetracyclododecane, or 12-crown-4, CAS N: 294-93-9

[0105] Lithium ion carrier VI: 6,6-dibenzyl-1,4,8,11-tetraoxacyclotetradecane, CAS N°: 106868-21-7

[0106] Lithium ion carrier VII: 2-(6-dodecyl-1,4,8,11-tetraoxacyclotetradec-6-yl)ethyl diethyl phosphate, CAS N°: 106868-29-5

[0107] Lithium ion carrier VIII: 2,2'-[[2-[[2-(dicyclohexylamino)-2-oxoethoxy]methyl]-2-ethyl-1,3-propanediyl]bis(oxy)]bis[N,N-dicyclohexylacetamide], CAS N: 133338-85-9

[0108] Lithium ion carrier X: N,N,N',N'-tetracyclohexyl-5,5-dimethyl-3,7-dioxanonanediamide, or 2,2'-[(2,2-dimethyl-1,3-propanediyl)bis(oxy)]bis[N,N-dicyclohexylacetamide], ETH 2015, CAS N: 108444-70-8

[0109] DETAILED DESCRIPTION

[0110] Experimental part

[0111] Mix one volume of organic formula with one volume of saline (O / A ext =1) and stirred at 800 rpm for 30 minutes at 23°C. After stopping stirring, the two phases were allowed to stand at 23°C for 5 to 30 minutes, and the aqueous phase and the organic phase were collected separately. The organic phase was then washed with deionized water (A / O de-ext =5) Back extraction was performed at 80 or 90° C. and 800 rpm for 35 minutes. After stopping the stirring, the two phases were allowed to stand at 80 or 90° C. for 10 to 15 minutes, and the two aqueous phases were finally analyzed by ion chromatography.

[0112] The extraction and stripping (regeneration) parameters are listed in Table 2.

[0113] [Table 2]

[0114]

[0115] Depending on the equipment, the extraction tests were performed using either an orbital shaker or an oscillator. On the other hand, the regeneration process was performed using only an oscillator, as it was the only device with a temperature-raising function.

[0116] The results are calculated from the analytical values ​​and corrected for the A / O factor and elution loss (calculated based on magnesium). To ensure accuracy, only the back-extraction values ​​are used.

[0117] Analytical equipment: Metrohm ion chromatograph,

[0118] Cation analysis column: Metrosep C6-150 / 4.0 (Cat. No. 6.1051.420)

[0119] Anion analysis column: Metrosep A Supp S 250 / 4.0 (Cat. No. 6.1006.530)

[0120] The following are several definitions needed to characterize the results of the subsequent experimental design.

[0121] Lithium ions (Li+) relative to metal ions (M n+ ) extraction rate (E M ), corrected extraction rate (E' M ), distribution coefficient (D M ), separation factor (SF (Li / M) ) and the extraction agent utilization rate (% Use (M)) are calculated according to formulas (1), (2), (3), (4) and (5), respectively:

[0122] or,

[0123] or,

[0124] or

[0125]

[0126] in and Represents M n+ Initial and final concentrations of ions in the aqueous extraction, stripping, and organic phases.

[0127] (O / A) ext with (O / A) de-extrepresent the volume ratios of the organic phase to the aqueous phase in the extraction and back-extraction stages, respectively.

[0128] In addition, considering the need for temperature-controlled liquid-liquid extraction, the equilibrium constant K eq (T) is highly dependent on the operating temperature and is therefore primarily governed by the enthalpy change (ΔH), which can be explained by the Arrhenius equation (5).

[0129]

[0130] It can be expressed in linear form:

[0131]

[0132] Experimental plan 1: Salt extraction using lithium ion carriers II, IV, V, VIII and X.

[0133] Adopted by The ion carrier (cationic extractant CE) was mixed with 10 equivalents of anionic solvating agent (AS), namely 450 mmol / L N-(3,5-bis(trifluoromethyl)phenyl)octanamide (C 16 H 19 An organic liquid formula consisting of 2,4-dichlorobenzene (2,4-dichlorobenzene) (F6NO, CAS N ゜1974318-14-3) was dissolved in 1,2-dichlorobenzene (2DCB) (C6H4Cl2, CAS N ゜95-50-1) and repeated extraction tests were performed on pure lithium chloride, sodium chloride, potassium chloride and calcium chloride aqueous solutions (all containing excess magnesium chloride).

[0134] The aqueous / brine phase used for the extraction test was prepared in the laboratory using deionized water and pure salt (>99.9%). The composition is detailed in Table 3.

[0135] [Table 3]

[0136]

[0137] The high salinity and chloride doping conditions were chosen to maximize the ionophore's ability to extract salts and to reduce uncertainty in the analysis of stripped ions using the selected products, which may have low extraction capacities for sodium chloride, potassium chloride, and calcium chloride.

[0138] The extraction and back-extraction protocols described above remained consistent across all tests.

[0139] The extraction results are shown in Table 4.

[0140] [Table 4]

[0141]

[0142]

[0143] Experiments show that the salt extraction capacity of tripod lithium carrier VIII is significantly higher than that of carriers II, IV and X, while the lithium extraction rate of carriers II and V (as lithium ion carriers for ion-selective electrodes) is extremely low.

[0144] The experimental results show that:

[0145] 1. The suitability of ionophores for selective cation exchange electrodes does not necessarily mean they are suitable for liquid-liquid salt extraction. For example, the salt extraction yield of lithium ionophore II (ETH 1644) was very low, ranging from 0.25 to 1.10 mmol / L, and the extractant utilization was consistently below 2.6%.

[0146] 2. Just because an ionophore is cation-selective in selective electrode applications does not necessarily mean it will also be cation-selective in liquid-liquid extraction. For example, although lithium ionophore V is classified as a lithium ionophore, it actually tends to extract NaCl more than LiCl, extracting 205 times more NaCl than LiCl.

[0147] 3. Lithium ionophores IV and X, which share highly similar structural components, exhibited similar performance, with extractant utilization rates of 19.2% and 15% for lithium, and 5.37% and 7.09% for sodium, respectively. On the other hand, lithium ionophore VIII achieved extractant utilization rates of 83% (lithium), 62.6% (sodium), and 76% (calcium) for pure salts.

[0148] 4. Compared with the "bipod-type" lithium ion carriers IV and X, the "tripod-type" lithium ion carrier VIII has a 4.33-fold increase in LiCl extraction efficiency.

[0149] Experimental Plan 2: Multi-salt co-extraction using 14-crown-4 ether crown ether

[0150] This experiment aims to The ion carrier (cationic extractant CE) and 3 equivalents of anionic solvating agent (AS), namely 240mmol / L N-(3,4-dichlorophenyl)octanamide (C 14 H 19 An organic liquid formulation consisting of 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS N°730-25-6) was dissolved in 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS N°694-80-4) to conduct a multi-salt co-extraction test on a simulated continental brine (containing lithium, sodium, potassium, magnesium chlorides, and calcium chloride) with excess sodium.

[0151] The brine used for the extraction test was prepared in the laboratory using deionized water and pure salt (>99.9%). The water components (ES-001) determined are detailed in Table 5.

[0152] [Table 5]

[0153]

[0154] This brine composition is representative of the brine characteristics produced from a wellhead when direct lithium extraction (DLE) or more precisely direct lithium salt extraction (DLSE) processes are practiced.

[0155] The aforementioned extraction and back-extraction scheme was maintained unchanged.

[0156] Given the extraction level of the ether-crown-based lithium ionophore V, this study focused on the 14-crown-4 ether type of crown ether. In addition to lithium ionophores VI and VII, the following two ionophores, which also exhibit lithium-selective electrode properties, were also tested.

[0157]

[0158] Dibenzo-14-crown-4-ol (DB14C4), CAS N°: 14174-06-2

[0159]

[0160] 6-[2-(Benzyloxy)ethyl]-6-dodecyl-14-crown-4-ol (BzO LiVII), CAS N°: 106868-24-0

[0161] The results are summarized in Table 6.

[0162] [Table 6]

[0163]

[0164]

[0165] Experiments showed that the four 14-crown-4 ether crown-based ionophores achieved only very limited lithium chloride extraction: for a formulation with 80 mmol / L extractant (EC), the extractant utilization (or loading) was less than 2.25%, and the lithium chloride extraction amount was less than 1.8 mmol / L.

[0166] Lithium ion carrier VIII, on the other hand, exhibited significant advantages: extractant utilization (or loading) reached 45.4%, and the formulation absorbed 36.30 mmol / L of lithium chloride. Furthermore, its separation factor (SF) was excellent, reaching "infinite" for Li / Mg and Li / Ca, 469 for Li / K, and 153 for Li / Na.

[0167] In summary, as shown in Table 7, the components of the treated brine are analyzed. ext = 1, the liquid-liquid extraction stage using lithium ion carrier VIII can achieve a lithium extraction rate of 28.5%, while the extraction rates of other ions are all less than 5%.

[0168] [Table 7]

[0169]

[0170] If the stripping formula is analyzed and the ion balance is calculated at 80°C using five times the volume of deionized water, the results show that Na + , K + Mg 2+ and Ca 2+ Impurities such as iodine and nitric acid were hardly extracted, while maintaining a lithium extraction rate of 25.4%, which is an even more advantageous result.

[0171] [Table 8]

[0172]

[0173] It is important to note the strong competition between lithium and calcium ions for the extractant: While the calcium chloride absorbed by the extractant alone reached 34.55 mmol / L in Experiment 1, no calcium chloride uptake was detected in this experiment under the coexistence of lithium ions. Another potential reason is that the anion-solvation solvent equivalent ratio (eq. AS) in this experiment was 3, compared to 10 in the previous experiment.

[0174] Given that experimental schemes 1 and 2 used 10 and 3 equivalents of anionic solvating agent (AS), respectively, this study investigated the effect of this parameter on the extraction capacity of 80 mmol / L lithium ion carrier VIII formulation in lithium chloride, sodium chloride, and calcium chloride, aiming to improve the utilization of the extractant.

[0175] Experimental Protocol 3: Extraction and Stoichiometric Chlorine Solvation Coefficient Studies

[0176] The pure aqueous solutions of lithium chloride, sodium chloride and calcium chloride, all containing excess magnesium chloride, were repeat Extraction tests were conducted using four organic liquid formulations: all containing Lithium ion carrier VIII was prepared with 1, 3, 5 and 10 equivalents of anionic solvating agent (AS), namely 80, 240, 400 and 800 mmol / L N-(3,5-bis(trifluoromethyl)phenyl)octanamide, respectively, all dissolved in 1,2-dichlorobenzene (2DCB).

[0177] The aqueous phases and brine used for extraction tests were prepared in the laboratory using deionized water and pure salt (>99.9%). The specific components are shown in Table 9.

[0178] [Table 9]

[0179]

[0180] All tests maintained the same extraction and back-extraction protocol as described above.

[0181] The results are summarized in Tables 10 to 13 and Figure 2 、 Figure 3 .

[0182] [Table 10]

[0183]

[0184] [Table 11]

[0185]

[0186]

[0187] [Table 12]

[0188]

[0189]

[0190] [Table 13]

[0191]

[0192]

[0193]

[0194] Experiments show that anionic solvating agents (AS) do play a role in promoting the transfer of salts to the organic phase - as the equivalent ratio (eq. SA) increases, the extraction amounts of lithium chloride, sodium chloride and calcium chloride all increase accordingly. Figure 2 The extraction rate and Figure 3 The extraction agent utilization rates shown all increased with increasing eq. SA, but experiments 3.1, 3.2, and 3.3 showed significant performance differences at equilibrium, indicating a significant increase in the selectivity for lithium.

[0195] The experiments show that the high selectivity of lithium ion carrier VIII makes its overall lithium extraction performance comparable to that of Experiments 1 and 2 regardless of the presence of sodium ions.

[0196] From the data in the table and figure, we can see that the equilibrium constant K eq There is a significant difference (Test 3.1 / 3.2: 68 / 1; Test 3.1 / 3.3: 161 / 1). Based on the equilibrium constant K eq The significant difference in the extraction efficiency and the non-extraction characteristics of magnesium and potassium ions make this formula particularly suitable for the selective extraction of lithium chloride in the presence of sodium chloride and / or calcium chloride.

[0197] Experimental plan 4: Organic phase / aqueous phase volume ratio (O / A ext ) on the effect of salt extraction

[0198] The anionic solvating agent (AS) containing 3 equivalents, namely N-(3,4-dichlorophenyl)octanamide (C 14 H 19 Cl2NO, CASN 730-25-6), wherein the initial concentration of lithium ion carrier VIII Dissolved in 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS N 694-80-4) in O / A ext Extraction tests were performed on polysaline brines in the range of 0.1 to 10.

[0199] The brine used for the extraction tests represents a true lithium-rich brine containing sulfate ions. It was prepared in the laboratory using deionized water and pure salt (>99.9%). Its salinity was 425 g / L, and its composition is detailed in Table 14.

[0200] [Table 14]

[0201]

[0202] The organic phase / aqueous phase volume ratio (O / A ext ) are 0.1, 0.25, 0.5, 1, 2, 4 and 10. These tests were used to evaluate the effect of this ratio on the extraction efficiency of each ion.

[0203] In addition to the above organic phase / aqueous phase volume ratio (O / A ext ), all other tests maintained the aforementioned extraction and back-extraction protocols unchanged.

[0204] The test results are summarized in Tables 15 to 17 and Figure 4 .

[0205] [Table 15]

[0206] <![CDATA[(O / A) ext ]]> 0.1 0.25 0.5 1 2 4 10 <![CDATA[E li (%)]]> 10.1％ 20.1％ 34.6％ 58.7％ 78.0％ 94.0％ 98.1％ <![CDATA[E Na (%)]]> 0.0％ 0.1％ 0.2％ 0.5％ 1.8％ 6.9％ 20.7％ <![CDATA[E k (%)]]> 0.0％ 0.00％ 0.00％ 0.00％ 0.00％ 0.00％ 0.00％ <![CDATA[E ca (%)]]> 0.5％ 1.2％ 2.6％ 6.5％ 14.8％ 39.6％ 72.6％ <![CDATA[E Mg (%)]]> 0.0％ 0.00％ 0.01％ 0.01％ 0.03％ 0.09％ 0.08％ <![CDATA[E SO4 (%)]]> 0.00％ 0.00％ 0.00％ 0.00％ 0.00％ 0.00％ 0.00％

[0207] Special attention should be paid to potassium ions (K + ), magnesium ions (Mg 2+ ) and sulfate ions (SO4 2- ) is not extracted at all.

[0208] [Table 16]

[0209]

[0210] [Table 17]

[0211] <![CDATA[(O / A) ext ]]> SF(Li / Na) SF(Li / K) SF(Li / Ca) SF(Li / Mg) <![CDATA[SF(Li / SO4)]]> 0.1 375 Infinity 22 5254 Infinity 0.25 309 Infinity 22 16561 Infinity 0.5 270 Infinity 19 4203 Infinity 1 266 Infinity 20 17425 Infinity 2 192 Infinity 20 10609 Infinity 4 212 Infinity 24 16973 Infinity 10 201 Infinity 20 69144 Infinity

[0212] This experiment proves that the tested formula is suitable for the selective extraction of lithium chloride in the coexistence of alkali metal and alkaline earth metal salts.

[0213] Based on this data, Figure 5 Also shown are the partition curves of lithium chloride between the organic and aqueous phases under constant temperature and pressure conditions, which we refer to as the lithium chloride absorption isotherm at 20°C for the excess chloride ion concentrations studied.

[0214] Experimental Plan 5: Calorimetric Determination of Methanol System at 25°C

[0215] To verify the effect of lithium ion carrier VIII on Li + , Ca 2+ And Na + The complexing ability of the two compounds was studied by isothermal titration calorimetry (ITC).

[0216] The experiments were performed at room temperature using GE Healthcare ITC200 and TA Instruments TAM 2277 calorimeters. The analytical solvent was methanol ( Tetraethylammonium chloride (Et4NCl) was used (Sigma-Aldrich) to set the ionic strength to 0.1 M. Stock solutions of lithium (0.1232 mol / L), calcium (0.1300 mol / L), and sodium (0.1074 mol / L) were prepared as chloride salts, and their concentrations were determined by ICP analysis.

[0217] In the ITC200 experiment, each titration consisted of 26 additions of 1.5 μL of metal stock solution into the analytical cell containing 0.2022 mL of the lithium ionophore VIII ligand with continuous stirring.

[0218] In the TAM 2277 experiment, each titration consisted of 17 additions of 15 μL of metal stock solution into a 1 mL analytical cell containing 0.8 mL of lithium ionophore VIII ligand solution with continuous stirring.

[0219] Each study involved multiple titrations to determine optimal analytical conditions, followed by multiple (at least three) replicates.

[0220] Ion carrier extractants CE00 (lithium VIII) and CE40 were prepared in a 1:1 stoichiometric ratio (M n+ :CE,M n+ =Li + 、Na + or Ca 2+ ) forms a complex. The complex equilibrium in the methanol system and the corresponding complex constant (K MeOH ) is defined as follows:

[0221] M n+ +CE<==>MCE,K MeOH =[MCE] / [M][CE]

[0222] (M=Li, Na or Ca and CE=Li VIII=CE00 or CE40)

[0223] The average test results of cationic extractants CE00 and CE40 are listed in Table 18.

[0224] [Table 18]

[0225]

[0226] aCalculated according to the relationship ΔG = -RT ln (K) (T = 298K, R = 8.314 J / mol / K)

[0227] bCalculated according to the relationship ΔG=ΔH-TΔS (T=298K).

[0228] The heat of the sodium chloride complexation reaction cannot be measured using equipment because the degree of complexation is too low.

[0229] These thermodynamic parameters (ΔH, ΔS) indicate that the complexation reaction between lithium and calcium is exothermic, with the negative enthalpy change ΔH dominating the calculation of the free enthalpy ΔG. For example, at T = 298 K, the |ΔH / (TΔS)| ratio for lithium complexation reaches 7, while for calcium complexation it is 2.8.

[0230] This indicates that the complexing ability of ion carriers CE00 and CE40 for these cations is significantly temperature-dependent, so a hot water extraction process was considered.

[0231] Experimental Protocol 6: Stripping of Loaded Salt Formula at 80°C

[0232] use Lithium ion carrier VIII and 3 equivalents of anion solvating agent (AS), namely 0.9 mol / L N-(3,4-dichlorophenyl)octanamide (C 14 H 19 Cl2NO, CAS N ゜730-25-6), all dissolved in 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS N ゜694-80-4), first extracted the brine at 23 ° C, and then by changing the A / O de-ext The stripping effect of 80°C deionized water on pre-absorbed salts was evaluated in the range of 0.02 to 5.

[0233] The brine used for extraction testing was prepared in the laboratory using deionized water and pure salt (>99.9%), which represents real lithium-rich brine.

[0234] After analysis and determination, its salinity is 360 g / L. The specific components are shown in Table 19.

[0235] [Table 19]

[0236]

[0237] A / O tested at 80℃ de-ext The values ​​are 0.02, 0.033, 0.05, 0.067, 0.1, 0.2, 0.5 and 5. These tests can be used to evaluate the effect of the ratio, i.e. the amount of deionized water used, on the stripping efficiency of each ion.

[0238] In addition to the above A / O de-ext and O / A as described below ext In addition, the aforementioned extraction and back-extraction schemes were maintained in all tests.

[0239] First, 95 mL of organic phase and 66.5 mL of brine were used to prepare the mixture (O / A). ext =1.43 for single contact extraction.

[0240] By analyzing the components of the treated brine, the liquid-liquid extraction performance is shown in Table 20.

[0241] [Table 20]

[0242]

[0243] As shown in Table 21, when the stripping formula is subjected to component analysis and ion balance calculation at 80°C using five times the volume of deionized water, the results show that the lithium extraction rate is increased from 69.3% to 74.5%, while, except for the extremely low initial concentration of calcium ions, the other impurity ions still maintain extremely low extraction rates.

[0244] [Table 21]

[0245]

[0246] The equilibrium data indicate that the formulation can achieve an initial and effective separation of lithium ions from other ions.

[0247] The results of stripping with deionized water at 80°C are summarized in Tables 22, 23 and Figure 6 、 7 .

[0248] [Table 22]

[0249]

[0250]

[0251] [Table 23]

[0252] <![CDATA[(O / A) de-ext ]]> 0.02 0.033 0.05 0.067 0.1 0.2 0.5 5 <![CDATA[E’ li (%)]]> 19.3％ 31.9％ 43.3％ 50.5％ 58.2％ 76.6％ 89.2％ 100％ <![CDATA[E’ Na (%)]]> 87.7％ 92.4％ 94.4％ 94.7％ 95.5％ 95.9％ 96.4％ 100％ <![CDATA[E’ k (%)]]> 100％ 100％ 100％ 88.4％* 91.5％* 91.4％* 90.6％* 100％ <![CDATA[E’ ca (%)]]> 59.4％ 82.0％ 82.7％ 91.2％ 93.7％ 95.6％ 96.2％ 100％ <![CDATA[E’ Mg (%)]]> 93.1％ 100％ 100％ 96.4％* 94.5％* 93.2％* 95.6％* 100％ <![CDATA[E’ SO4 (%)]]> 57.8％ 65.5％ 72.1％ 76.3％ 80.2％ 84.9％ 90.7％ 100％

[0253] *Within analytical precision.

[0254] Based on this result, Figure 8 The distribution curve of lithium chloride between the organic phase and the aqueous phase under constant temperature and pressure conditions is also shown, which we call the isotherm of lithium chloride stripping with deionized water at 80°C.

[0255] By combining Figure 5 and Figure 8 , Figure 9 Two lithium partition curves at 20°C and 80°C during the separation and purification of lithium chloride are shown.

[0256] The differences between these isotherms reflect the possible “breathing effect” of this formulation when subjected to temperature-controlled lithium chloride liquid-liquid extraction.

[0257] like Figure 10 As shown, these lithium chloride partition isotherms can be used to construct the corresponding McCabe-Thiele plots to determine the theoretical number of stages required for the extraction and stripping stages given the two operating line conditions.

[0258] Experimental Plan 7: Extractable Nitrates and Other Diionic Salts (LiNO3, NaNO3) and Triionic Salts (Ca(NO3)2) Adoption research

[0259] This experiment aims to use the Lithium ion carrier VIII and 3 equivalents of anion solvating agent (AS), namely 750mmol / L N-(3,4-dichlorophenyl)octanamide (C 14 H 19 An organic liquid formulation consisting of 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS N°730-25-6) was dissolved in 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS N°694-80-4) to extract pure lithium nitrate, sodium nitrate, and calcium nitrate aqueous solutions (with or without excess magnesium nitrate) at varying concentrations.

[0260] The aqueous phases and brine used for extraction tests were prepared in the laboratory using deionized water and pure salt (>99.9%). The specific components are detailed in Table 24.

[0261] [Table 24]

[0262]

[0263]

[0264] All tests maintained the same extraction and back-extraction protocol as described above.

[0265] At 20℃, (O / A )ext = 1, for each initial aqueous phase component, five separation isotherms at 20 ° C were obtained (such as Figure 11), characterizing the relative concentration relationship of each salt in the organic extraction phase and the aqueous phase under equilibrium state.

[0266] The experiments showed that for salts doped with LiNO3 and Ca(NO3)2, the 0.25 mol / L formulation quickly reached saturation, while NaNO3 was only slightly absorbed. This demonstrates that, like chloride salts, diionic nitrates are also extractable.

[0267] Experimental Plan 8: Study on the Density and Viscosity Changes of Lithium Ion Carrier VIII Formulations

[0268] This experiment aimed to evaluate the effect of the relative concentrations of cationic extractant and anionic solvating agent on the density and viscosity of the formulations at 20°C. To this end, different formulations of lithium ionophore VIII and N-(3,4-dichlorophenyl)octanamide, both dissolved in 2-chlorobromobenzene (2CBB), were implemented for different relative concentrations of CE and AS.

[0269] The experimental results are summarized in Figure 12 and Figure 13 .

[0270] Experiments have shown that, under fixed AS equivalent conditions, density decreases linearly with increasing CE concentration. It should also be noted that when treating brine with a density of 1.22 kg / L, a certain CE concentration cannot be exceeded if the formulation density needs to be maintained above 1.27 kg / L.

[0271] Experiments have shown that as the concentration of lithium ion carrier VIII extractant increases, the viscosity of the formulation may limit its industrial application in liquid-liquid extraction systems, especially in processes using gravity settlers - when the viscosity of the continuous phase is high, sedimentation separation will be more difficult.

[0272] To this end, this study investigated other compounds to find extractants that could reduce viscosity while maintaining good lithium selectivity and extraction performance. Liquid extractants are of particular interest due to their potential high solubility and low formulation viscosity.

[0273] A compound having the following formula:

[0274]

[0275] The synthesis of the target compound requires three consecutive reaction stages.

[0276] Stage 1: Synthesis of secondary amines

[0277]

[0278] Step 1: Place the ketone (10 mmol, 1 eq), solvent (17 vol), amine (45 mmol, 4.5 eq), and reagents in a clean, dry flask. Heat as needed, depending on the reagents. Monitor the conversion by thin-layer chromatography (TLC) for the disappearance of the starting ketone. Distill the solvent (and any residual amine) under reduced pressure. Filter through celite, if necessary, and add methanol (12 vol). Add sodium borohydride (30 mmol, 3 eq) in portions, if necessary, and stir at room temperature for 1 to 15 hours.

[0279] If necessary, purification was performed by silica gel column chromatography (gradient elution from dichloromethane to dichloromethane / ethyl acetate). The yield was 20-77%.

[0280] Stage 2: Synthesis of Chloroacetamide

[0281]

[0282] Place the previously prepared amine (10 mmol, 1 equivalent), dichloromethane (3 volumes, 15 equivalents), and triethylamine (30 mmol, 3 equivalents) in a flask. Add chloroacetyl chloride (20-25 mmol, 2-2.5 equivalents) at low temperature under an argon atmosphere. Shake the reaction at room temperature for 5-24 hours. After adding 2 volumes of water, back-extract the aqueous phase twice with 2 volumes of dichloromethane. Concentrate the organic phase by rotary evaporation.

[0283] Purify by silica gel column chromatography (eluted with 100% dichloromethane), yield 30-70%.

[0284] Phase 3: Synthesis of target compound

[0285]

[0286] Sodium hydride (3.5-4 equivalents) and 10 volumes of anhydrous tetrahydrofuran are added to a three-necked flask. Heat the medium to reflux under an argon atmosphere. A hot solution of the triol in 10 volumes of THF and the chloroacetamide compound in 15-20 volumes of THF are added sequentially. Stir the medium under reflux for 1-24 hours. Neutralize the reaction medium by adding 10 volumes of water. Back-extract the aqueous phase twice with 5 volumes of dichloromethane. Wash the organic phase 1-2 times with 5 volumes of water. Concentrate the organic phase by rotary evaporation.

[0287] The crude product was purified by silica gel column chromatography (eluent: heptane / ethyl acetate). The yield was usually 50-70%.

[0288] Table 25 lists the formulas of the synthesized compounds, in which lithium ion carrier VIII was renamed CE00.

[0289] [Table 25]

[0290]

[0291]

[0292]

[0293] Tables 26 and 27 list the characteristic parameters of the synthesized compounds.

[0294] [Table 26]

[0295]

[0296] [Table 27] (Me = methanol)

[0297]

[0298] Experimental Plan 9: Extractant Synthesis and Formula Density

[0299] With the completion of the synthesis of different extractants CE00 to CE39, the effects of 0.2 and 0.3 mol / L CE molar concentrations on the density of 3-5 mL formulations were investigated under the conditions of 3 equivalents of anionic solvating agent. Some of the results are shown in Figure 2. Figure 14 shown.

[0300] The experimental data showed a reasonable pattern. The higher the molar mass of the extractant, the more significant the negative impact on the formulation density.

[0301] Therefore, it is worthwhile to reduce the molar mass of the extractant, and its lower limit depends on the solubility of the substance in water.

[0302] Experimental Protocol 10: Viscosity of Low Molecular Weight Extractant Formulations

[0303] Given that the viscosity test requires 15-20 mL of a formulation solution, it was decided to synthesize a low-molar-weight and easily synthesized extractant to obtain Et-NPiperidine (CAS N゜405264-17-7) (1H NMR: 4.02 (s, 6H), 3.53-3.40 (m, 6H), 3.34 (s, 12H), 1.54 (dd, J=20.0, 14.4 Hz, 18H), 1.38 (d, J=7.6 Hz, 2H), 0.81 (t, J=7.6 Hz, 3H)). The preparation amount exceeded 50 grams, which was used to prepare a formulation product containing 1.5 to 5 grams of the extractant.

[0304] In addition to the low molar mass of the product, its conversion to an oil indicates that the tested formulation represents the lowest viscosity level achievable for this type of tripodal extractant.

[0305] The experimental results are summarized in Figure 15 .

[0306] Experiments show that the viscosity is reduced by an average of 53%, and a CE concentration of 400 mmol / L can be achieved at 20°C, which is close to the 20 centipoise limit. The extraction capacity is improved by about 33% compared with the lithium ion carrier VIII / CE00 formula.

[0307] Experimental Protocol 11: Extraction Performance of Target Compounds

[0308] The purpose of this experiment was to test the new cationic extractants CE01 to CE39 in full accordance with the method of Experimental Protocol 1 above.

[0309] Some of the extraction results are listed in Table 28.

[0310] [Table 28]

[0311]

[0312] The experimental results show that:

[0313] 1. Except for CE39 Et-N (morpholine), all compounds maintain high extraction efficiency for lithium, K eq (Li) fluctuates but K eq (Na) and K eq (Ca) always maintains a low value;

[0314] 2. Liquid extractants can be easily obtained through amide group (R1, R2) functionalization;

[0315] 3. The cyclic and / or branched structures of R1 and R2 are beneficial to improve the Li / Na selectivity, thereby enhancing the Li + / Na + Extraction performance;

[0316] 4. The use of straight-chain alkyl groups with a carbon number greater than 4 can improve the Li / Ca selectivity and promote the Li + / Ca2 + extraction;

[0317] 5. The introduction of long-chain alkyl, branched-chain alkyl or electron-donating groups into R3 can improve the utilization rate of the extractant;

[0318] 6. Replacing the hydrogen atoms of R4, R5 and / or R6 with at least one short-chain alkyl group can reduce the melting point of the extractant while increasing the lithium extraction capacity.

[0319] Based on the positive results above, the study further conducted extraction experiments with polysalt brine at 20°C and back-extraction experiments at 80°C for the formulation containing the target extractant. Some of the results are shown below.

[0320] Experimental Plan 12: Verification of the selective extraction of lithium chloride using a formulation containing CE21 using various tripodal extractants applicability.

[0321] Adopted by Ionophore CE21 and 4 equivalents of anionic solvating agent (AS), namely 320mmol / L N-(3,4-dichlorophenyl)octanamide (C 14 H 19 The organic liquid formula consists of Cl2NO, CAS 730-25-6), which is completely dissolved in 2-chlorobromobenzene (2CBB) C6H4BrCl, CAS 694-80-4, firstly extracting the polysalt brine at 23 ° C, and then mixing it with A / O de-ext Deionized water with a ratio of 0.2 and 1 was contacted at 80°C to evaluate the stripping effect of pre-absorbed salts. These tests were used to evaluate the effect of the ratio on the stripping efficiency of each ion.

[0322] The brine used for extraction testing was prepared in the laboratory using deionized water and pure salt (>99.9%), which represents real lithium-rich brine.

[0323] After analysis and determination, its salinity is 286.5 g / L, and the ion components are detailed in Table 29.

[0324] [Table 29]

[0325]

[0326] In addition to the above A / O de-ext In addition, the aforementioned extraction and back-extraction schemes were maintained in all tests.

[0327] First, 10 mL of organic phase and 10 mL of brine were mixed at (O / A) ext =1 for single contact extraction.

[0328] The liquid-liquid extraction performance data are shown in Table 30.

[0329] [Table 30]

[0330]

[0331] The stripping results of 80°C deionized water are summarized in Tables 31 and 32.

[0332] [Table 31]

[0333]

[0334] [Table 32]

[0335]

[0336] In comparison, the extraction performance data using CE00 (lithium ion carrier VIII) instead of CE21 are listed in Table 33.

[0337] [Table 33]

[0338]

[0339] Lithium extraction increased from 13.2% to 33.1%, and more importantly, calcium extraction decreased from 14.3% to 3.5%. It should be noted that the separation factors (SF) for all cations were significantly improved.

[0340] Tests on other tripod-type extractants showed that, for example, liquid extractant CE11 achieved a lithium extraction rate of 30.1% and a calcium extraction rate of 4.5%, with other extractants performing even better.

[0341] example:

[0342] Adopted by Ionophore CE11 and 3 equivalents of anionic solvating agent (AS), namely 1.02 mol / L N-(3,4-dichlorophenyl)octanamide (C 14 H 19 The invention discloses an organic liquid formulation consisting of an organic liquid consisting of Cl2NO3, CAS 730-25-6) dissolved entirely in 2-chlorobromobenzene (2CBB) (C6H4BrCl, CAS 694-80-4). The invention aims to achieve a liquid-liquid extraction process of lithium chloride by temperature regulation between a 20°C to-be-treated polysalt brine and 80°C deionized water. The extraction is carried out at 20°C using a four-stage mixer-settler, and the back extraction is carried out at 80°C using a three-theoretical-stage stirred tower.

[0343] The lithium chloride extraction stage was carried out at 20°C with a concentration of (O / A) ext =1.1, the stripping stage was carried out at 80 ° C with (O / A) de-ext =10 implementation.

[0344] The brine used for the extraction test was prepared in the laboratory using deionized water and pure salt (>99.9%), based on the composition data from the Maricunga Salt Flats in Chile.

[0345] After analysis and determination, its salinity is 306.4 g / L, and its components are detailed in Table 34.

[0346] [Table 34]

[0347]

[0348] The relevant McCabe-Thiele diagram is Figure 16 .

[0349] The process flow chart of this embodiment is shown in Figure 17 .

[0350] The four-stage extraction process is achieved by connecting four mixers [1a] to [4a] in series and four settlers [1dc] to [4d] in series, with [1dc] being a centrifugal settler. Heat exchangers [1e] and [2e] are used to heat the organic phase and cool the stripping water, respectively. Finally, a hot countercurrent stripping column is shown in [1c].

[0351] Table 35 lists the material balance data for an annual production of 12,285 tons of lithium chloride, where the flow rate at the feed [A1] is 21.5 tons of water / hour).

[0352] The lithium extraction and production yield of this process reaches 93%.

[0353] [Table 35]

[0354]

[0355]

[0356] By using an intermediate washing step of the organic phase after the basic material balance in the brine after the lithium chloride extraction stage, the purity of the desorbed lithium chloride can be significantly improved. wash =0.05 extraction, a single-stage washing of the organic phase was performed, so that the sodium ion concentration in the stripping solution was reduced from 0.486 mol / L to 0.076 mol / L (SF=3330), and the calcium ion concentration was reduced from 0.272 mol / L to 0.026 mol / L (SF=865), without causing any significant deterioration in the lithium production yield. ext At 1.1, it only dropped from 93% to 90.5%.

[0357] Experimental Scheme 13: Introduction of other extractants in this family and corresponding lithium / sodium selectivity experimental results.

[0358] Compounds CE40 to CE43 were synthesized and incorporated into various formulations for experimentation.

[0359] [Table 36]

[0360]

[0361] Extractants CE40 to CE43 are all in solid form and are unknown in the literature (Table 37).

[0362] The aim of this study was to extract the cellulose matrix from a 0.1 mol / L cationic extractant (CE) with 8 equivalents of anionic solvating molecules (ASM), namely 0.8 mol / L N-(3,4-bis(dichlorophenyl)octanamide (C 14 H 19The organic liquid formula composed of Cl2NO, CAS N゜730-25-6) was completely dissolved in 1-bromo-2-chlorobenzene (2CBB) (C6H4BrCl, CAS N゜694-80-4) and the aqueous solution containing 0.1mol / LLiCl, 0.1mol / LNaCl and excess 1.5mol / LMgCl2 was repeatedly Li + / Na + Selective extraction test, the test objects are ionophores CE00, CE02, CE27, CE40 and CE43.

[0363] [Table 37]

[0364]

[0365] The saline aqueous phase used for extraction tests was prepared in the laboratory using deionized water and pure salt (>99.9%).

[0366] All tests were performed according to the extraction and back-extraction protocol described above.

[0367] The experimental results are listed in Tables 38 and 39 below.

[0368] [Table 38]

[0369]

[0370] [Table 39]

[0371]

[0372] Experiments have shown that the extractant's "head" R3 plays a decisive role in the selectivity of lithium and sodium cations, while the amine selected by R1 and R2 has little effect on the sodium extraction rate, which remains low in the presence of lithium. Therefore, CE extractants can be wisely selected based on the ionic composition of the lithium-rich brine to be treated to achieve optimal technical and economic performance.

[0373] Experimental plan 14: Selective extraction of lithium chloride using a variety of anionic solvating molecules in combination with the extractant CE02 Behavior.

[0374] The purpose of this experiment was to test the lithium chloride extraction of an aqueous solution containing 0.05 mol / L LiCl and an excess of 1.5 mol / L MgCl2 using an organic liquid formulation consisting of 0.1 mol / L of the cationic extractant CE02 and 5 equivalents of anionic solvating molecules (ASM), i.e., 0.5 mol / L, all dissolved in 1,2-dichlorobenzene (DCB) (C6H4Cl2, CAS 90-50-1). A total of 12 anionic solvating molecules (ASMs) were investigated.

[0375] The saline aqueous phase used for extraction tests was prepared in the laboratory using deionized water and pure salt (>99.9%).

[0376] All tests were performed according to the extraction and back-extraction protocol described above.

[0377] The lithium chloride extraction rates corresponding to the solvated molecules of each anion are listed in Table 40 below.

[0378] [Table 40]

[0379]

[0380]

[0381]

[0382] Experiments have shown that combining the lithium extractant molecule CE02 with any of the aforementioned anion solvating molecules (in this case, the anion is Cl-) and dissolving them in a polar aromatic solvent, in this case 1-bromo-2-chlorobenzene (2CBB), can achieve efficient extraction of lithium chloride from the aqueous phase to the organic phase via the liquid-liquid pathway described in the present invention.

[0383] Reference List:

[0384] [1]Gabra&Torma-Hydrometallurgy,1978,3,pp.23-33

[0385] [2]Bukowsky&Uhlemann-Separation science and Technology,1993,28(6),pp.1357-1360

[0386] [3]Hano&al-Solvent Extraction and Ion Exchange,1992,10(2),pp.195-206

[0387] [4]D.Gao&al-Journal of Chemical Engineering of Japan, 2016, Vol.49, No.2, pp.104-110

[0388] [5]Zhou&al-J.Chem.Eng.Data 2011,56,pp.3518-3522

[0389] [6]Zhou&al-Ind.Eng.Chem.Res,2012,51,pp.12926-12932

[0390] [7]Hui-fang&al-Hydrometallurgy,2016,160,pp.1-5

[0391] [8]Zhou&al-ACS Sustainable Chem.Eng,2019,7,9,pp.8885-8892

[0392] [9]Kamenica&al-Sensors,2017,17,pp 2430。

Claims

1. A hydrophobic organic liquid composition for selectively extracting a diionic lithium salt from a lithium-rich brine to be treated, wherein the diionic lithium salt comprises a lithium cation and a complementary group of lithium cations, particularly selected from Cl-, I-, Br- - , CN-, NO3, HCO3 anions, the composition comprising: (A) at least one lithium cation extracting compound selected from the group consisting of: in: - R1 and R2 may be the same or different, regardless of their position on the nitrogen atom, and are independently selected from a linear or branched C1-C 12 Alkyl, aryl, C4-C8 cycloalkyl; or - R1 and R2, together with the nitrogen atom carrying them, form a five-membered, six-membered, seven-membered or eight-membered ring; -R3 is selected from hydrogen, linear or branched C1-C8 alkyl, C4-C8 cycloalkyl, C2-C6 alkoxyalkyl and alkoxyalkylaryl; -R4 is selected from hydrogen, linear or branched C1-C3 alkyl; -R5 is selected from hydrogen, linear or branched C1-C3 alkyl; -R6 is selected from hydrogen, linear or branched C1-C3 alkyl; (B) at least one hydrophobic protic organic compound for solvating an anion complementary to the lithium cation; and (C) at least one hydrophobic polar organic diluent having a flash point greater than 60°C, preferably greater than 75°C, more preferably greater than 90°C at atmospheric pressure.

2. The hydrophobic organic liquid composition according to claim 1, wherein The molar mass of the lithium cation extracting compound is at least 450 g / mol, preferably at least 550 g / mol.

3. The hydrophobic organic liquid composition according to any one of claims 1 or 2, characterized in that The complexation constant Log K of the lithium cation extraction compound for the cation in methanol at 25°C is at least 1, preferably greater than 2.

4. The hydrophobic organic liquid composition according to any one of claims 1 to 3, characterized in that The lithium cation extraction compound has a negative enthalpy change ΔH when complexing lithium cations, and at a temperature T=298K, the absolute value of the ratio of the enthalpy change ΔH of the complexed lithium cations to the entropy change ΔS of the complexed lithium cations |ΔH / (TΔS)| is greater than 2, preferably greater than 5.

5. The hydrophobic organic liquid composition according to any one of claims 1 to 4, characterized in that The melting point of the lithium cation extracting compound is below 200°C, preferably below 50°C, more preferably below 25°C.

6. The hydrophobic organic liquid composition according to any one of claims 1 to 5, characterized in that - R1 and R2, regardless of their position on the nitrogen atom, are each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 2-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, 2-ethylhexyl, phenyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl; or - R1 and R2, together with the nitrogen atom carrying them, form a pyrrolidine, piperidine, azepane or azacyclooctane ring; -R3 is selected from hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 2-methylbutyl, 2-ethylpropyl, n-hexyl, cyclohexyl, methoxymethyl, methoxyethyl, methoxypropyl, methoxybutyl and -CH2-O-CH2-phenyl; and - R4, R5 and R6 are hydrogen or methyl; When the calcium concentration in the brine to be treated exceeds 10g / L and / or Li + / Ca 2+ Optionally, R1 and R2 are advantageously selected from butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl or phenyl; and When the calcium concentration in the brine to be treated is lower than 10g / L and / or Li + / Na + When selective, R1 and R2 are advantageously selected from isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 2-ethylpropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, or R1 and R2 together with the nitrogen atom carrying them form a pyrrolidine, piperidine, azepane or azacyclooctane ring.

7. The hydrophobic organic liquid composition according to any one of claims 1 to 6, characterized in that The lithium cation extracting compound may be selected from:

8. The hydrophobic organic liquid composition according to any one of claims 1 to 7, wherein The hydrophobic protic organic compound for solvating anions complementary to lithium cations has a pKa value in water at 25°C of at least 9, preferably at least 10.5, and preferably less than the pKa value of water at 25°C, or at least less than 15 at 25°C, and a solubility in water at 25°C of less than 0.01 mol / L.

9. The hydrophobic organic liquid composition according to claim 8, wherein The hydrophobic protic organic compound used to solvate the anion complementary to the lithium cation may be a compound of formula (B): in: -R B 、R C and R D At least one of the free radicals, which may be the same or different, is a halogen atom or an electron-withdrawing group selected from the group consisting of: F, Cl, Br; C m F 2m+1 , m≤4, m is a non-zero integer; CF2CF2C p H 2p+1 , p≤4, p is an integer; CF2C p H 2p+1 , p≤4, p is an integer; CH2C p F 2p+1 , p≤4, p is an integer; OCH2CF3; C(=O)CF3; C m H n F p Cl q Br s , m≤4, n, p, q, s are integers and at least one of p, q or s is not zero; C(=O)OC m H 2m+1 , m≤4, m is an integer; C(=O)C m H 2m+1 , m≤4, m is an integer; -The rest of R A 、R B 、R C 、R D and R E Free radicals, which are the same or different, are selected from the following non-electron-withdrawing free radicals: H; CH3; CH2CH3; CH2CH2C p F 2p+1 , p≤4, p is an integer; C m H 2m-1 , m≤10, m is an integer greater than 1; C m H 2m+1 , m≤10, m is a non-zero integer; and R A to R E Only one free radical can be the latter two C m H 2m-1 or C m H 2m+1 One of the free radicals; and -X is selected from the following radicals: .OH; where R A 、R B 、R C 、R D and R E They may be the same or different and are defined as in the above formula (B); R' and R", which may be the same or different, are selected from the following radicals: H; C n H 2n-1 , n≤4, n is an integer greater than 1; C n H 2n+1 , n≤4, n is a non-zero integer; CH2CH2C p F 2p+1 , p≤4, p is an integer; CH2C p F 2p+1 , p≤4, p is an integer; CF2C p H 2p+1 , p≤4, p is an integer; CF2CF2C p H 2p+1 , p≤4, p is an integer; C m F 2m+1 , m≤4, m is a non-zero integer; C m H n F p Cl q Br s , m≤4, n, p, q, s are integers and at least one of p, q or s is not zero; R'' is selected from the following radicals: C m H 2m+1 , m≤20, m is an integer; C m H 2m-1 , m≤20, m is an integer greater than 1; C m H n F p Cl q Br s , m≤10, n, p, q, s are integers and at least one of p, q or s is not zero; CH2CH2C p F 2p+1 , p≤4, p is an integer; CH2C p F 2p+1 , p≤4, p is an integer; CF2C p H 2p+1 , p≤4, p is an integer; CF2CF2C p H 2p+1 , p≤4, p is an integer; C m F 2m+1 , m≤4, m is a non-zero integer; and an aryl radical of formula (b): where R A 、R B 、R C 、R D and R E , which may be the same or different, are defined as the aforementioned molecular formula (B).

10. The hydrophobic organic liquid composition according to claim 9, wherein In the compound of formula (B), X can be represented by:

11. The hydrophobic organic liquid composition according to claim 10, wherein Compound (B) can be represented by the following molecular formula: (C): Wherein R'' is selected from the following radicals: C m H 2m+1 , m≤20, preferably ≤15, m is an integer; C m H 2m-1 , m≤20, m is an integer greater than 1; C m H n F p Cl q Br s , m≤10, n, p, q, s are integers and at least one of p, q or s is not zero; and an aryl radical of formula (b): where R A 、R B 、R C 、R D and R E They may be the same or different and are defined as the molecular formula (B) in claim 8.

12. The hydrophobic organic liquid composition according to claim 11, wherein The free radical R'' is -C7H 15 、Positive-C9H 19 、Positive-C 11 H 23 or positive-C 13 H 27 .

13. The hydrophobic organic liquid composition according to any one of claims 1 to 12, characterized in that The concentration of the at least one lithium cation extracting compound in the composition may be from 0.15 to 1 mol / L, preferably from 0.3 to 1 mol / L, more preferably from 0.45 to 1 mol / L.

14. The hydrophobic organic liquid composition according to claim 13, wherein The molar concentration ratio of the at least one hydrophobic protic organic compound for solvating anions complementary to the lithium cation to the at least one lithium cation extracting compound is 1 to 10, preferably 1.5 to 5, more preferably 2 to 4.

15. The hydrophobic organic liquid composition according to any one of claims 1 to 14, characterized in that The viscosity of the hydrophobic polar organic diluent at 20° C. is less than 5 mPa·s, preferably less than 2 mPa·s.

16. The hydrophobic organic liquid composition according to any one of claims 1 to 15, characterized in that The density at 20°C may be greater than 1.20 kg / L, preferably greater than 1.25 kg / L, more preferably greater than 1.30 kg / L, and the viscosity at 20°C is less than 50 mPa·s, preferably less than 25 mPa·s, for use in brine to be treated having a density at 20°C that is at least 0.05 kg / L lower.

17. The hydrophobic organic liquid composition according to any one of claims 1 to 15, characterized in that The density at 20°C may be greater than 1.25 kg / L, preferably greater than 1.30 kg / L, more preferably greater than 1.35 kg / L, and the viscosity at 20°C is less than 30 mPa·s, preferably less than 15 mPa·s, for brine to be treated having a density at 20°C of at least 0.15 kg / L lower.

18. A compound selected from the group consisting of the following molecular formulas:

19. Use of the hydrophobic organic liquid composition according to any one of claims 1 to 17 in a lithium salt extraction process, characterized in that: The process includes: a step of mixing a hydrophobic organic liquid composition with brine to be treated at a first temperature, a step of separating the hydrophobic organic liquid composition loaded with lithium salt from the treated brine, and a step of regenerating the hydrophobic organic liquid composition by treating the hydrophobic organic liquid composition loaded with lithium salt and treated water, wherein the regeneration step is carried out at a second temperature higher than the first temperature, and the temperature difference between the first temperature and the second temperature is 30 to 150°C, preferably 50 to 100°C, and more preferably 60 to 80°C.

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