Compositions and methods for extracting lithium from an aqueous solution

Abstract

Disclosed are reagent compositions containing at least one lithium selective extractant such as a lithium selective extractant. The reagent compositions can also include at least one modifier to stabilize complexes formed between the lithium and the extractant. Also disclosed are methods and apparatus for extracting lithium from aqueous solutions using the reagent compositions.

Description

COMPOSITIONS AND METHODS FOR EXTRACTING LITHIUM FROM ANAQUEOUS SOLUTIONFIELD

[0001] The disclosure relates to reagent compositions and methods for extracting lithium (e.g., lithium salts) from an aqueous solution.BACKGROUND

[0002] In the world’s transition to clean energy, electricity storage platforms play an important role. Lithium batteries are at the forefront of electricity storage technologies because inter alia they charge faster, last longer and have a higher power density to provide more battery life in a lighter package than conventional batteries. Lithium storage devices are useful for electrification of the transportation sector, electric vehicles, battery storage for electric utilities and in many other applications to reduce carbon emissions and store electricity.

[0003] Lithium is typically extracted from underground deposits of brine water and ore made of compounds containing lithium. Brines from salars and salt lakes, as well as spodumene ores, are the primary sources of lithium, while geothermal brines represent secondary sources. Classical methods of lithium extraction rely on brine evaporation in open ponds to maximize element concentration for further purification; however, these methods are very slow (evaporation of ponds to the desired level can take up to 24 months) and strongly dependent on region-specific weather conditions that vary throughout the year. Newer technologies based on precipitation, adsorption, solvent extraction and membranes can be used for brine concentration and may increase theeconomic viability of minerals extracted from seawater and other geothermal brines. However, there is a need for improved compositions and methods for isolating lithium (e.g., lithium salt) from a brine solution.BRIEF SUMMARY

[0004] According to one or more embodiments, described herein are reagent compositions, comprising: at least one lithium selective extractant (e.g., a zwitterionic extractant) capable of extracting lithium (e.g., a lithium salt) from an aqueous solution; and optionally, at least one modifier. The at least one lithium selective extractant comprises one or more compounds having the following formula (I) or (II):(I) (II) wherein R1, R2and R3is each independently a chemical bond, hydrogen, a methyl group, a straight or branched C2-C20 alkyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S, and wherein R / '-O is a carboxylate anion, a sulfur trioxide anion, an acetamide anion, which may be interrupted by a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S.

[0005] In one or more embodiments, the at least one lithium selective extractant comprises one or more compounds having the following formula (III):wherein R5is a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S, and wherein R6-O- is a carboxylate anion, a sulfur trioxide anion, an acetamide anion, which may be interrupted by a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S.

[0006] According to one or more embodiments, the lithium selective extractant comprises one or more compounds having the following formulas:

[0007] In one or more embodiments, the at least one lithium selective extractant includes one or more compounds having the following formula (XI) or (XII):(XI) (XII) wherein R7, R8and R9is each independently a methyl group, a straight or branched C2-C20 alkyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, a phenyl group, a C2-C20 alkylphenyl group, an amine group, a C1-C20 alkyl amine group, a C4-C9 cycloalkyl group, a carboxamide group, or an alkyl carboxamide group, wherein each of the foregoing alkyl, alkenyl, alkynyl, phenyl, alkylphenyl, alkyl amine, carboxamide, and alkyl carboxamide groups may be interrupted by N, O, S, carbonyl, or a cycloalkyl.

[0008] In one or more embodiments, the at least one lithium selective extractant is present in the reagent composition in an amount of about 5 wt% to about 100 wt%, based on the total weight of the reagent composition.

[0009] In embodiments where the at least one modifier is present in the reagent composition, the at least one modifier comprises one or more functional group having a dipole moment and / or that is attached to a highly polar ionic bond. In some embodiments, the at least one modifier comprises an aliphatic component that is attracted to non-polar moieties of the at least one lithium selective extractant. In one or more embodiments, the at least one modifier comprises one or morefunctional group chosen from a diether, amide, imide, ketone, alcohol, ether, alkyl phosphine, phosphate, ester, phosphonic acid, phosphonic acid, phosphoric acid and / or nitrile.

[0010] According to various embodiments, where the modifier is present in the reagent composition, the at least one modifier is chosen from 1,6-di-t-butoxy hexane, N,N- Dimethyldecanamide, Di(ethylene glycol) dibutyl ether, N,N-Dimethyldecanamide, N,N- Diethyldodecanamide, N,N-Diethyl-2-ethyl hexanamide, 1,4-bis- t-Butoxy butane, 2-Ethylhexyl succinimide, 4-t-butylcyclohexanone, iminodiacetic acid (IDA), Dodecanol, 2,2,4-Trimethyl-l,3- pentanediol diisobutyrate (TXIB), Ethyoxylated isotridecyl phosphate (TDA), Cydecanol, 7- Ethyl-2-methyl-undecanol, Trimethyl nonanol, 4-Isopropyl cyclohexanone, t-Butyl octyl ether, 3- Isopropyl cyclohexanone, 3,3,5-Trimethyl cyclohexanone, Methyl n-propyl ketone (Eastman C- 11 Ketone), 5-Ethyl-2-nonanone, a mixture of phosphine oxides (Cyanex 923), Tributyl phosphate, 6-Undecanone, Heptyl 2-ethylbutyrate, 2-Ethylbutyl caproate, and / or 3-(Cyclohexyl)- propionitrile.

[0011] According to various embodiments of reagent composition, the at least one modifier is present in an amount of about 0 wt% to about 95 wt%, based on the total weight of the reagent composition. In embodiments where the modifier is present, the reagent composition may have a weight ratio of the at least one lithium selective extractant to the at least one modifier of about 1 : 1 to about 100: 1.

[0012] Further described herein according to various embodiments are methods of extracting lithium (e g., one or more lithium salts) from an aqueous solution, comprising: contacting the aqueous solution with a reagent composition according to embodiments herein; and extracting the lithium from the aqueous solution into the reagent composition until reaching equilibrium to form a lithium depleted aqueous phase and a lithium rich organic phase. The aqueous solution can beany lithium bearing aqueous solution including, but not limited to, a lithium-containing brine, brine from a salar, product stream from a pond evaporation process, product stream from a processing plant, or combinations thereof. Optionally, the aqueous solution may be contacted with a magnesium selective reagent composition prior to contacting the aqueous solution with the reagent composition to extract the lithium (e.g., one or more lithium salts). In some embodiments, the aqueous solution contains one or more lithium salts such as lithium chloride, lithium sulfate, lithium hydroxide, lithium nitrate or combinations thereof.

[0013] Embodiments of methods as described herein further include contacting the lithium (e.g., lithium salt) depleted aqueous phase with fresh reagent composition and further extracting the lithium (e.g., one or more lithium salts) from the aqueous solution into the lithium rich organic phase until reaching equilibrium, and optionally repeating the further extracting with fresh reagent composition until the lithium depleted aqueous phase is free or substantially free of lithium (e.g., lithium salts). In various embodiments, the methods further comprise emulsifying the lithium rich organic phase. Methods according to embodiments herein may further comprise separating the lithium depleted aqueous phase from the lithium rich organic phase.

[0014] According to one or more embodiments of the described methods, the overall extraction of lithium from the aqueous solution is greater than about 70%, greater than about 80%, greater than about 90%, greater than about 92%, or about 70% to about 99%, or about 80% to about 93. The selectivity of lithium over magnesium may be about 1 to about 50, about 5 to about 30, or about10 to about 25.SUMMARY OF THE DRAWINGS

[0015] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like references indicate similar elements.

[0016] FIG. 1 shows a representation of zwitterionic extraction of an inorganic salt.

[0017] FIG. 2 is a chart showing the kinetics (percent extraction as a function of time) for a zwitterionic reagent according to embodiments herein.

[0018] FIG. 3 is a chart showing magnesium removal from a lithium brine solution combined with a zwitterionic reagent according to embodiments herein during a solvent extraction process.Definitions

[0019] Reference throughout this specification to, for example, “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “In one or more embodiments” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0020] As used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise. Thus, for example, reference to “a depurator vessel” includes a single depurator vessel as well as more than one depurator vessel.

[0021] As used herein, the term “about” in connection with a measured quantity, refers to the normal variations in that measured quantity as expected by one of ordinary skill in the art in makingthe measurement and exercising a level of care commensurate with the objective of measurement and the precision of the measuring equipment. In certain embodiments, the term “about” includes the recited number ±10%, such that “about 10” would include from 9 to 11.

[0022] The term “at least about” in connection with a measured quantity refers to the normal variations in the measured quantity, as expected by one of ordinary skill in the art in making the measurement and exercising a level of care commensurate with the objective of measurement and precisions of the measuring equipment and any quantities higher than that. In certain embodiments, the term “at least about” includes the recited number minus 10% and any quantity that is higher such that “at least about 10” would include 9 and anything greater than 9. This term can also be expressed as “about 10 or more.” Similarly, the term “less than about” typically includes the recited number plus 10% and any quantity that is lower such that “less than about 10” would include 11 and anything less than 11. This term can also be expressed as “about 10 or less.”

[0023] Unless otherwise indicated, all parts and percentages are by weight. Weight percent (wt. %), if not otherwise indicated, is based on an entire composition free of any volatiles, that is, based on dry solids content.

[0024] The term “trace” or “trace amount” as used herein refers to the amount of a component in a solution being less than about 1 part per million by weight (ppmw).

[0025] The term “substantially free” as used herein refers to trace amounts of a component in a fluid, less than trace amounts of the component in the fluid or a non-detectable amount of the component in the fluid.

[0026] The term “interrupted” as used herein in relation to a chemical group refers to a chemical group containing at least one, for example, halogen, sulfur, nitrogen, oxygen, cycloalkane, and so on. In some embodiments, this may be viewed as a substitution of at least one carbon with one ofthe listed groups (i.e., halogen, sulfur, nitrogen, etc.). For example, the following alkane group is interrupted with an oxygen: CH3-O-CH2-CH2-CH2-CH3. In another example, a cyclohexane interrupted with nitrogen and sulfur may have the following structure:

[0027] Reference throughout this specification to a chemical element refers to the element itself, compounds, salts and molecules containing the chemical element. For example, “lithium” alone refers to lithium ions, lithium metal, lithium compounds, lithium salts and lithium-containing molecules.DETAILED DESCRIPTION

[0028] Embodiments of the disclosure are described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, example features. The features can, however, be embodied in many different forms and should not be construed as limited to the combinations set forth herein; rather, these combinations are provided so that this disclosure will be thorough and complete and will fully convey the scope. The following detailed description is, therefore, not to be taken in a limiting sense.

[0029] Disclosed herein according to one or more embodiments are reagent compositions including a class of zwitterionic extractants useful for extracting lithium salt from a brine solution. The reagent compositions may include at least one lithium selective extractant (e.g., a zwitterionic extractant) capable of extracting a lithium salt from an aqueous solution, and optionally at least one modifier that stabilizes the organic / inorganic salt system. The zwitterion can be native (always active) or it can be induced through resonance or other mechanisms such as proton exchange.

[0030] Selectivity is the measure of the transfer of a desired salt from the aqueous phase to the organic phase as compared to the transfer of other salts. Lithium selective extractants have a wide range of selectivity. Suitable lithium selective extractants useful in reagent compositions according to various embodiments preferentially extract lithium chloride. Equation 1 can be used to determine the selectivity of the lithium chloride extraction as compared to the extraction of other salts.(transferti / feedLi) / (transferion / Feedion) = selectivity for lithium (1)

[0031] Further disclosed in one or more embodiments are methods employing reagent compositions. The reagent compositions used in the methods include lithium selective extractants suitable to bind with, isolate and / or extract a lithium salt from a brine solution during a solvent extraction process. In one or more embodiments, the solvent extraction process can be used without acids or bases.

[0032] The described methods according to various embodiments are efficient (i.e., up to about 99% lithium extraction and at least about 90% stripping efficiency) at extracting lithium as a salt from a brine solution containing a high amount of magnesium. Such brines cannot be treated using conventional extraction methods.

[0033] Reagent compositions according to one or more embodiments herein contain at least one lithium selective extractant. Suitable lithium selective extractants can extract lithium salts from a solution (e.g., an aqueous lithium brine solution, an aqueous lithium-containing solution, etc.) in a solvent extraction process. Suitable lithium salts include, but are not limited to, lithium chloride (LiCl), lithium sulfate, lithium hydroxide, lithium nitrate and / or combinations thereof.

[0034] Suitable lithium selective extractants are lithium salt extractants having a positive charge and a negative charge on the same organic molecule. The presence of both positive and negativecharges makes these compounds intra-ion organic salts. Such compounds can be self-associating within a bulk organic solution. When contacted with a solution containing inorganic salts, an inorganic-organic double salt (IODS) can be formed as shown in FIG. 1.

[0035] As shown in FIG. 1, a zwitterionic extractant may be part of a resonance structure. The zwitterion has both positive and negative charges, similar to an amino acid. The zwitterionic extractant is suitable for extracting lithium salts including lithium chloride (LiCl) as a salt. Zwitterions can exist as a native species, where the cation and anion are ever present, or as an induced species, where the anion and cation can be formed by changes in a resonance structure, proton extraction, etc.

[0036] Examples of lithium selective extractants (e.g., having zwitterions) suitable for use in the reagent compositions according to embodiments herein include, but are not limited to, one or more compounds having the following formula (I) or (II):(I) (II) wherein R1, R2and R3is each independently a chemical bond, hydrogen, a methyl group, a straight or branched C2-C20 alkyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the alkyl, alkenyl or alkynyl groups may be interrupted by N, O and / or S, and wherein R4-O' is a carboxylate anion, a sulfur trioxide anion, an acetamide anion, which may be interrupted by a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S. Such tertiary and quaternary amine compoundsare suitable for binding to the lithium in solution and extracting the lithium from the aqueous phase into the organic phase.

[0037] In one or more embodiments, the at least one lithium selective extractant (additionally or alternatively) includes one or more compound having the following formula (III):wherein R5is a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S, and wherein R6-O- is a carboxylate anion, a sulfur trioxide anion, an acetamide anion, which may be interrupted by a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S. Such imidazole-based compounds are suitable for binding to the lithium in solution and extracting the lithium from the aqueous phase into the organic phase.

[0038] According to one or more embodiments, the lithium selective extractant includes one or more compounds having the following formulas:

[0039] In various embodiments, the at least one lithium selective extractant (additionally or alternatively) includes one or more compounds having the following formula (XI) or (XII):(XI) (XII) wherein R7, R8and R9is each independently a methyl group, a straight or branched C2-C20 alkyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, a phenyl group, a C2-C20 alkylphenyl group, an amine group, a C1-C20 alkyl amine group, a C4-C9 cycloalkyl group, a carboxamide group, or an alkyl carboxamide group, wherein each of the foregoing alkyl, alkenyl, alkynyl, phenyl, alkylphenyl, alkyl amine, carboxamide, and alkyl carboxamide groups may be interrupted by N, O, S, carbonyl, or a cycloalkyl. Such compoundsare suitable for binding to the lithium in solution and extracting the lithium from the aqueous phase into the organic phase.

[0040] In one or more embodiments, the extractant is an amide-based extractant wherein R7and R8in Formula (XI) are each independently a C3-C6 branched alkyl, or any individual compound within this definition. In some embodiments, the extractant is an amide-based extractant wherein R7and R8is each independently, a methyl or branched C3-C9 alkyl, or any individual compound within this definition, with the proviso that only one of R7or R8is methyl. In at least one embodiment, R7is a branched C3-C9 alkyl, and R8is a straight C2-C9 alkyl, or any individual compound within this definition. In one or more embodiments, R7is a straight C2-C9 alkyl and R8is a branched C3-C9 alkyl. In one or more embodiments, the extractant is a phenyl urea-based extractant wherein at least one or two of R7, R8and R9is phenyl or a straight or branched C3-C9 alkylphenyl. In some embodiments, the extractant is a phenyl urea-based extractant wherein R7is a branched C3-C7 alkyl, R8is an amine group or a C3-C7 alkylamine group, and R9is phenyl or a straight or branched C3-C7 alkylphenyl, or any individual compound within this definition. In at least one embodiment, R7and R9is each independently phenyl or a straight or branched C3-C7 alkylphenyl, and R8is an amine group or a C3-C7 alkylamine group, or any individual compound within this definition. In one or more embodiments, the extractant is a dicarboxamide-based extractant wherein R7in Formula (XI) is a branched C3-C7 alkyl interrupted by an N and R8is a branched C3-C8 alkyl carboxamide.

[0041] In one or more embodiments, the at least one lithium selective extractant is present in the reagent composition in an amount of about 5 wt% to about 100 wt%, or any individual value or sub-range within this range, based on the total weight of the reagent composition. In various embodiments, reagent compositions may include an organic solvent, which may also function asa modifier, and the one or more lithium selective extractant. Suitable organic solvents include, but are not limited to, an aliphatic hydrocarbon, aromatic hydrocarbon, amine, ester, ether, ketone, nitrated or chlorinated hydrocarbon, or combinations thereof. In some embodiments, the organic solvent contains kerosene, hexane, toluene, dichloromethane, diethyl ether, acetone, chloroform, or combinations thereof. The reagent composition may contain the organic solvent in amount of greater than 0 wt% to about 95 wt%, based on the total weight of the reagent composition, or any individual value or sub-range within this range.

[0042] Reagent compositions according to one or more embodiments herein further include at least one modifier. Suitable modifiers are able to stabilize an IODS once formed. Stabilization is beneficial, for example, when the polarity of the organic phase is typically not high enough to stabilize the highly ionic character of the IODS. Modifiers according to one or more embodiments herein can have functional groups with a dipole moment and / or may be attracted to the highly polar ionic bonds. Suitable modifiers according to embodiments may also have an aliphatic component that is attracted to the non-polar moieties of the zwitterionic extractants. This attraction essentially “shields” the ionic moieties and helps to solubilize the IODS.

[0043] Modifiers according to various embodiments of reagent compositions can contain a variety of functional groups that are polar. In embodiments where the at least one modifier is present in the reagent composition, the at least one modifier comprises one or more functional group having a dipole moment and / or that is attached to a highly polar ionic bond. In some embodiments, the at least one modifier comprises an aliphatic component that is attracted to non-polar moieties of the at least one lithium selective extractant. In one or more embodiments, the at least one modifier comprises one or more functional group chosen from a diether, amide, imide, ketone, alcohol,ether, alkyl phosphine, phosphate, ester, phosphonic acid, phosphonic acid, phosphoric acid and / or nitrile.

[0044] A non-exhaustive list of suitable modifiers for reagent compositions is provided in Table1.Table 1 - Modifiers Suitable for Use with Lithium Selective ExtractantsFunctional . ...Modifier MW group1,6-di-t-butoxy hexane Diether 230.39N,N-Dimethyldecanamide Amide 199.34 Di(ethylene glycol) dibutyl ether Diether 218.34 N,N-Dimethyldecanamide Amide 199.34 N,N-Diethyldodecanamide Amide 255.44N,N-Diethyl-2-ethyl hexanamide Amide 199.34 1,4-bis-t-Butoxy butane Diether 202.342-Ethylhexyl succinimide Imide 211.30 4-t-butylcyclohexanone Ketone 154.25IDA Alcohol 158.28Dodecanol Alcohol 186.34TXIB Diester 300.44TDA Alcohol 200.38Cydecanol Alcohol 148.007-Ethyl-2-methyl-undecanol Alcohol 214.39Trimethyl nonanol Alcohol 186.34 4-Isopropyl cyclohexanone Ketone 140.23 t-Butyl octyl ether Ether 186.343 -Isopropyl cyclohexanone Ketone 140.23 3,3,5-Trimethyl cyclohexanone Ketone 140.23 Eastman C-l 1 Ketone Ketone 170.305 -Ethyl -2-nonanone Ketone 170.30FunctionalModifier MW groupCyanex 923 Alkyl Phosphine 348Tributyl phosphate Phosphate 266.326-Undecanone Ketone 170.30Heptyl 2-ethylbutyrate Ester 214.352-Ethylbutyl caproate Ester 228.383-(Cyclohexyl)-propionitrile Nitrile 137.22

[0045] According to various embodiments, the at least one modifier is present in the reagent composition in an amount of about 0 wt% to about 95 wt%, based on the total weight of the reagent composition, or any individual value or sub-range within this range. In embodiments where the modifier is present, the reagent composition may have a weight ratio of the at least one lithium selective extractant to the at least one modifier of about 1 : 1 to about 100: 1, or any individual value or sub-range within this range.

[0046] While most extractants require a diluent or solvent to maintain a low viscosity, reagent compositions according to various embodiments herein are suitable as neat formulations (i.e., without an organic solvent) of the at least one lithium selective extractant (e.g., one or more zwitterionic extractants). In some embodiments, reagent compositions do not comprise a modifier. In some embodiments, the unloaded reagent composition containing the at least one lithium selective extractant, and optionally the at least one modifier, has a viscosity of about 0.1 cP to about 1000 cP, or any individual value or sub-range within this range, as measured by using a Brookfield viscometer Model RVF, spindle No. 2, at 2 rpm, at 20°C.

[0047] In one or more embodiments, the at least one lithium selective extractants may be present in the reagent composition in an amount of about 5 wt% to about 100 wt%, about 10 wt% to about 95 wt%, about 20 wt% to about 80 wt%, about 50 wt% to about 70 wt%, or any individual valueor sub-range within these ranges, based on the total weight of the reagent composition. In one or more embodiments, the at least one modifier may be present in the reagent composition in an amount of about 0 wt% to about 95 wt%, about 1 wt% to about 90 wt%, about 5 wt% to about 80 wt%, about 20 wt% to about 50 wt%, or any individual value or sub-range within these ranges, based on the total weight of the reagent composition. According to various embodiments, when at least one modifier is present, the reagent composition contains a weight ratio of the at least one lithium selective extractant to the at least one modifier of about 1 : 1 to about 100:1, about 2: 1 to about 50: 1, about 10:1 to about 20: 1, or any individual value or sub-range within these ranges. In one or more embodiments, the reagent composition contains about 70 wt% lithium selective extractant and about 30 wt% modifier. Each aqueous brine solution containing lithium salts may be suitably extracted with different amounts of the lithium selective extractant and modifier.

[0048] Depending on the composition of the brine, lithium can be found in the form of a salt including lithium chloride, lithium sulfate, lithium hydroxide, lithium nitrate, etc. In some embodiments, when reagent compositions are combined with a brine solution, so long as there is a substantially equimolar quantity of chloride to lithium in the brine, lithium chloride will be extracted. While other salts may be less preferred, extraction of any lithium salts is beneficial. Selectivity of lithium over other ions, particularly magnesium (Mg), is beneficial. Reagent compositions according to embodiments herein may provide a selectivity of Li / Mg of at least about 2, at least about 3, at least about 5, at least about 7, about 7.5 to greater than 20, or any individual value or sub-range within these ranges, in a solvent extraction system.

[0049] In some embodiments, the extraction kinetics for the reagent compositions to extract lithium salts from an aqueous solution (e.g., a lithium brine) is relatively fast. The extraction kinetics are based on the time to reach equilibrium. As shown in FIG. 2, a lithium selectiveextractant (i.e ., a zwitterionic extractant) was combined with a lithium brine solution and the extraction kinetics were measured. As shown in FIG. 2, the lithium salt extraction percent at 2 minutes was essentially the same as the extraction percent at 48 minutes. For this lithium selective extractant and aqueous brine system, a mixing time of about 2 minutes was determined to adequately reach equilibrium.

[0050] Further described herein according to various embodiments are methods of extracting one or more lithium salts from an aqueous solution, comprising: contacting the aqueous solution with a reagent composition according to embodiments herein; and extracting the one or more lithium salts from the aqueous solution into the reagent composition until reaching equilibrium to form a lithium salt depleted aqueous phase and a lithium salt rich organic phase. The aqueous solution can be any lithium bearing aqueous solution including, but not limited to, a lithium-containing brine, brine from a salar, product stream from a pond evaporation process, product stream from a processing plant, or combinations thereof. Optionally, the aqueous solution may be contacted with a magnesium selective reagent composition prior to contacting the aqueous solution with the reagent composition to extract the one or more lithium salts. According to various embodiments, the one or more lithium salts comprised in the aqueous solution comprise lithium chloride, lithium sulfate, lithium hydroxide, lithium nitrate or combinations thereof.

[0051] According to one or more embodiments of the described methods, the overall extraction of lithium from the aqueous solution is greater than about 70%, greater than about 80%, greater than about 90%, greater than about 92%, or about 70% to about 99%, or about 80% to about 93, or any individual value or sub-range within these ranges. The selectivity of lithium over magnesium may be about 1 to about 50, about 5 to about 30, or about 10 to about 25, or any individual value or sub-range within these ranges.

[0052] According to one or more embodiments, transfer of lithium (e.g., LiCl) from the aqueous solution to a different medium occurs by making an emulsion (i.e., an organic phase) to increase the surface area of the organic phase. To make the emulsion, agitation, stirring and / or centrifuging is performed while the aqueous solution contacts the organic solution containing the reagent composition. The lithium selective extractant binds with the lithium salts at the interface between the brine and emulsion forming an IODS in a novel solvent-solvent extraction process. Once extraction of the one or more lithium salts with the reagent composition is complete (e.g., after about 1 min to about 1 h, about 2 min to about 30 min, or any individual value or sub-range within these ranges, of contact between the brine and the reagent composition), the emulsion rich in IODS is allowed to coalesce.

[0053] Once coalesced, the organic phase can be easily separated from the brine phase now depleted of lithium (e.g., lithium salts). The organic phase can be washed and / or scrubbed to remove entrained water and / or loaded impurities. In various embodiments, methods further include stripping the lithium from the lithium salt rich organic phase, optionally, wherein about 70% to about 99%, or about 95% of the lithium is stripped from the lithium salt rich organic phase. The washed organic phase may then be stripped with water. This stripping process is possible because the extraction process does not experience an activation / deactivation mechanism using acid and / or base.

[0054] Embodiments of methods as described herein further include contacting the lithium depleted aqueous phase with fresh reagent composition and further extracting the lithium (e.g., one or more lithium salts) from the aqueous solution into the lithium rich organic phase until reaching equilibrium, and optionally repeating the further extracting with fresh reagent composition until the lithium depleted aqueous phase is free or substantially free of lithium. Invarious embodiments, the methods further comprise emulsifying the lithium rich organic phase. Methods according to embodiments herein may further comprise separating the lithium depleted aqueous phase from the lithium rich organic phase.EXAMPLESExample 1

[0055] An organic solution (i.e., reagent composition) was formulated with 50% v / v lithium selective extractant and 50% v / v modifier. The extractants evaluated include an amide-based extractant (El), a urea-based extractant (E2), and a phenyl urea-based extractant (E3). A process brine from the lithium industry (feed) was stirred at 25°C. The organic solution was mixed with the process brine at an organic to aqueous weight ratio of 5:1 using a pump impeller operating at 1750 rpm until equilibrium was reached. During the mixing, lithium chloride was extracted from the aqueous phase and into the organic phase. Upon reaching equilibrium, fresh (non-loaded) reagent composition was added to the mixture two additional times (SI, S2). The results of the brine extraction are shown in Table 3.Table 3 - Results of brine extraction Example 1.

[0056] Table 3 contains the data for the feed and the three individual extractions. These organic lots were then stripped in two sets of aqueous at an organic to aqueous weight ratio of 1 : 1. The cumulative transfer was the sum of the ions in the two strip solutions, multiplied by five (5) to compare with the feed composition. Overall extraction of lithium from brine was 92.7%. Approximately 95% of the lithium was subsequently stripped from the organic. Selectivity of lithium over magnesium was about 23 using Eq. 1. Transfer of other ions was minimal.Example 2

[0057] The experiment in Example 1 was repeated. The extractants evaluated were El, E2 and E3 (discussed in Example 1) and a dicarboxamide-based extractant (E4). Conditions were similar, with a change in mixing time. In this case, the extraction efficiency was 99% after four contacts (SI, S2, S3, S4) of fresh reagent composition with the aqueous brine solution. All of the organic samples were stripped to form four respective strip solutions. The stripping of the first two organic samples resulted in a complete transfer of lithium. Stripping of the third organic transferred 92% of lithium, and of the fourth transferred 81%. The results are shown in Table 4.Table 4 - Results of brine extraction Example 2.Example 3

[0058] Stripping of the loaded organic solution was conducted using the same conditions as Example 2. Concentrating the stripping solution by successively stripping lithium chloride loaded organic into the stripping solution resulted in a loss of stripping efficiency as the concentration of LiCl increased. As the concentration of the aqueous strip solution increases, the stripping efficiency of the organic decreases. Stripping into a solution up to about 17,000 ppm lithium chloride resulted in 100% stripping efficiency. As the concentration approached about 25,000 ppm lithium, the stripping efficiency dropped to 80%. The results are shown in Tables 5A and 5B.Table 5A - Li content in Sample (25,000 ppm) Table 5B - Li content in Sample (17,000 ppm)

[0059] These results indicate that a 25,000 ppm solution of lithium chloride can be combined with the reagent composition while still providing a high selectivity. The resulting solution can be treated in a number of ways. It can be directly converted to lithium carbonate using standard industrial methods, it can be further purified with a magnesium selective reagent, or if the magnesium is low enough, it can be sent to bipolar electrodialysis to be converted to LiOH. In addition, this solution can be treated with any number of methods to provide battery grade material.

[0060] Focusing on a magnesium selective reagent to polish this solution, either an ion exchange, electrodialysis, solvent extraction, etc. method can be used to remove the magnesium from the concentrated lithium chloride stream. For example, a solvent extraction method can perform these types of purifications.Example 4

[0061] In this example, an extraction x wash x strip stage (ExWxS) solvent extraction configuration was used together with a standard extractant activated by displacing a proton. The resulting anion was capable of forming a complex with cations. A magnesium selective reagent was used to “polish’ the magnesium from a concentrated lithium solution while controlling the pH. The percent extraction as a function of pH is shown in FIG. 3. By controlling the pH to below 4, the magnesium was extracted without extraction of lithium. Different magnesium extraction reagents can be used. The range of pH where they can be used is from about 1 to about 10 where the lithium isotherm curve is to the right of the magnesium extraction curve. See FIG.3

[0062] Table 6 shows the results of a dynamic circuit in which a magnesium removal reagent (i.e., organic extractant) was incorporated. As shown, the organic extractant was able to remove 99.5% of the magnesium and 99.4% of the calcium. Coupled with the selectivity of the zwitterionic reagents, this resulted in a very pure concentrated lithium product that could be directly converted into battery grade lithium hydroxide or lithium carbonate. The selectivity of Li / Mg was about 7.5 to about 20 in extraction system.Table 6 - Magnesium extraction results from dynamic circuit testing.

[0063] The foregoing description discloses example embodiments of the disclosure. Modifications of the above-disclosed assemblies, apparatus, and methods which fall within the scope of the disclosure will be readily apparent to those of ordinary skill in the art. Accordingly,while the present disclosure has been disclosed in connection with example embodiments, it should be understood that other embodiments may fall within the scope of the disclosure, as defined by the following claims.

[0064] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

CLAIMSWhat is claimed is:

1. A reagent composition, comprising: at least one lithium selective extractant capable of selectively extracting lithium from an aqueous solution; and optionally at least one modifier.

2. The reagent composition of claim 1, wherein the at least one lithium selective extractant comprises one or more compounds having the following formula (I) or (II):(I) (II) wherein R1, R2and R3is each independently a chemical bond, hydrogen, a methyl group, a straight or branched C2-C20 alkyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S, and wherein R4-O’ is a carboxylate anion, a sulfur trioxide anion, an acetamide anion, which may be interrupted by a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S.

3. The reagent composition of claim 1 or 2, wherein the at least one lithium selective extractant comprises one or more compounds having the following formula (III):wherein R5is a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S, and wherein R6-O’ is a carboxylate anion, a sulfur trioxide anion, an acetamide anion, which may be interrupted by a methyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, wherein each of the C2-C20 alkyl, alkenyl or alkynyl groups may be interrupted by N, O or S.

4. The reagent composition of any preceding claim, wherein the at least one lithium selective extractant comprises one or more compounds having the following formulas:

5. The reagent composition according to any preceding claim, wherein the at least one lithium selective extractant comprises one or more compounds having the following formula (XI) or (XII):(XI) (XII) wherein R7, R8and R9is each independently a methyl group, a straight or branched C2-C20 alkyl group, a straight or branched C2-C20 alkenyl group, a straight or branched C2-C20 alkynyl group, a phenyl group, a C2-C20 alkylphenyl group, an amine group, a C1-C20 alkyl amine group, a C4-C9 cycloalkyl group, a carboxamide group, or an alkyl carboxamide group, wherein each of the foregoing alkyl, alkenyl, alkynyl, phenyl, alkylphenyl, alkyl amine, carboxamide, and alkyl carboxamide groups may be interrupted by N, O, S, carbonyl, or a cycloalkyl.

6. The reagent composition of any preceding claim, wherein the at least one modifier comprises one or more functional group having a dipole moment and / or that is attached to a highly polar ionic bond.

7. The reagent composition of any preceding claim, comprising the at least one modifier, wherein the at least one modifier comprises an aliphatic component that is attracted to non-polar moi eties of the at least one lithium selective extractant.

8. The reagent composition of any preceding claim, comprising the at least one modifier, wherein the at least one modifier comprises one or more functional group chosen from a diether, amide, imide, ketone, alcohol, ether, alkyl phosphine, phosphate, ester, phosphonic acid, phosphonic acid, phosphoric acid and / or nitrile.

9. The reagent composition of any preceding claim, comprising the at least one modifier, wherein the at least one modifier is chosen from 1,6-di-t-butoxy hexane, N,N- Dimethyldecanamide, Di(ethylene glycol) dibutyl ether, N,N-Dimethyldecanamide, N,N- Di ethyl dodecanami de, N,N-Diethyl-2-ethyl hexanamide, 1,4-bis- t-Butoxy butane, 2-Ethylhexyl succinimide, 4-t-butylcyclohexanone, iminodiacetic acid (IDA), Dodecanol, 2,2,4-Trimethyl-l,3- pentanediol diisobutyrate (TXIB), Ethyoxylated isotridecyl phosphate (TDA), Cydecanol, 7- Ethyl-2-methyl-undecanol, Trimethyl nonanol, 4-Isopropyl cyclohexanone, t-Butyl octyl ether, 3- Isopropyl cyclohexanone, 3,3,5-Trimethyl cyclohexanone, Methyl n-propyl ketone (Eastman C- 11 Ketone), 5-Ethyl-2-nonanone, a mixture of phosphine oxides (Cyanex 923), Tributyl phosphate,6-Undecanone, Heptyl 2-ethylbutyrate, 2-Ethylbutyl caproate, and / or 3-(Cyclohexyl)- propionitrile.

10. The reagent composition of any preceding claim, comprising the at least one lithium selective extractant in an amount of about 5 wt% to about 100 wt%, based on the total weight of the reagent composition.

11. The reagent composition of any preceding claim, comprising the at least one modifier in an amount of about 0 wt% to about 95 wt%, based on the total weight of the reagent composition.

12. The reagent composition of any preceding claim, comprising the at least one modifier, wherein a weight ratio of the at least one lithium selective extractant to the at least one modifier is about 1 :1 to about 100: 1.

13. A method of extracting one or more lithium salts from an aqueous solution, comprising: contacting the aqueous solution with the reagent composition of any preceding claim; and extracting the one or more lithium salts from the aqueous solution into the reagent composition until reaching equilibrium to form a lithium salt depleted aqueous phase and a lithium salt rich organic phase.

14. The method of claim 12, wherein the aqueous solution is lithium-containing brine, brine from a salar, product stream from a pond evaporation process, product stream from a processing plant, or combinations thereof,optionally, wherein the aqueous solution is contacted with a magnesium selective reagent composition prior to contacting the aqueous solution with the reagent composition to extract the one or more lithium salts.

15. The method of claim 12 or 13, wherein the one or more lithium salts comprised in the aqueous solution comprises lithium chloride, lithium sulfate, lithium hydroxide, lithium nitrate or combinations thereof.

16. The method of any one of claims 12 to 14, further comprising contacting the lithium salt depleted aqueous phase with fresh reagent composition and further extracting the one or more lithium salts from the aqueous solution into the lithium salt rich organic phase until reaching equilibrium, and optionally repeating the further extracting with fresh reagent composition until the lithium salt depleted aqueous phase is free or substantially free of lithium salts.

17. The method of any one of claims 12 to 15, further comprising emulsifying the lithium salt rich organic phase.

18. The method of any one of claims 12 to 16, further comprising separating the lithium salt depleted aqueous phase from the lithium salt rich organic phase.

19. The method of any one of claims 12 to 17, further comprising stripping the lithium from the lithium salt rich organic phase,optionally, wherein about 70% to about 99%, or about 95% of the lithium is stripped from the lithium salt rich organic phase.

20. The method of any one of claims 12 to 18, wherein the overall extraction of lithium from the aqueous solution is greater than about 70%, greater than about 80%, greater than about 90%, greater than about 92%, or about 70% to about 99%, or about 80% to about 93.

21. The method of any one of claims 12 to 19, wherein the selectivity of lithium over magnesium is about 1 to about 50, about 5 to about 30, or about 10 to about 25.