EP4728107A2

EP4728107A2 - Compositions, apparatus, systems and methods for extracting a metal from an aqueous solution

Info

Publication number: EP4728107A2
Application number: EP24824209.1A
Authority: EP
Inventors: Jack Bender; Amit PATWARDHAN; Keith Anderson
Original assignee: Energy Exploration Technologies Inc
Current assignee: Energy Exploration Technologies Inc
Priority date: 2023-06-16
Filing date: 2024-06-14
Publication date: 2026-04-22
Also published as: AR133354A1; WO2024259211A2; WO2024259211A3; WO2024259209A3; WO2024259209A2; AR133355A1

Abstract

Disclosed are systems and methods for recovering a metal from an aqueous solution. The systems may include an adsorption system having an adsorbent that is selective for a target metal. The adsorption system may include an inlet for an aqueous solution containing metals at least one of which is the target metal. Further described are raffinate compositions for use as an eluent to an adsorption process.

Description

COMPOSITIONS, APPARATUS, SYSTEMS AND METHODS FOR EXTRACTING A METAL FROM AN AQUEOUS SOLUTION

FIELD

[0001] The disclosure relates generally to compositions, apparatus, systems and methods for extracting one or more target metals (e.g., lithium) from an aqueous solution (e.g., a brine solution).

BACKGROUND

[0002] Conventional metal (e.g., lithium) extraction processes are expensive, time-consuming, and non-sustainable. Such processes typically use evaporation ponds to selectively separate a target metal (e.g., lithium ions, lithium salts, lithium chloride, etc.) from other metals in aqueous brines. These processes are time-consuming and use significant amounts of water in arid regions where water is a precious commodity. Utilizing water for these processes causes environmental damage and governments have begun discouraging the practice.

[0003] Solutions to conventional metal extraction are taking time to develop and often have inherent flaws or significant cost hurdles to overcome. Developed and commercialized solutions remain expensive and utilize high quantities of reagents and/or water. There remains a need for improved systems, compositions and methods for recovering a metal such as lithium from an aqueous solution that minimize water consumption, reduce cost and increase efficiency.

BRIEF SUMMARY

[0004] Described herein according to various embodiments are raffinate compositions from a solvent extraction process for use as an eluent to an adsorption process. The raffinate compositions may include a solvent and at least one metal dissolved in the solvent. In embodiments, the adsorption eluent is at a pH suitable for adsorption of a target metal by an adsorbent. In one or more embodiments, the adsorption eluent is at a temperature suitable for adsorption of the target metal by an adsorbent. The at least one metal may be at a concentration of about 1 ppmw to about 1000 ppmw, or any individual value or sub-range within this range. The at least one metal may include at least one metal cation, for example, chosen from lithium, calcium, magnesium, potassium, boron, sodium, or combinations thereof. In one or more embodiments, the at least one metal comprises at least one metal anion, for example, chosen from a halide, a sulfate, a nitrate, or combinations thereof.

[0005] The pH of the raffinate composition may be about 2 to about 11, or any individual value or sub-range within this range. The temperature of the raffinate composition may be about 5°C to about 65°C, or any individual value or sub-range within this range.

[0006] According to various embodiments, the at least one metal is chosen from lithium, sodium, potassium, magnesium, calcium, boron, or combinations thereof. In one or more embodiments, the at least one metal comprises: i) lithium at a concentration of about 0 ppmw to about 800 ppmw, ii) sodium at a concentration of about 0 ppmw to about 20,000 ppmw, iii) potassium at a concentration of about 0 ppmw to about 20,000 ppmw, iv) magnesium at a concentration of about 0 ppmw to about 2,000 ppmw, v) calcium at a concentration of about 0 ppmw to about 4,000 ppmw, vi) boron at a concentration of about 0 ppmw to about 2,000 ppmw, or any combination of i)-vi), or any individual value or sub-range within these ranges. In some embodiments, the at least one metal comprises: i) lithium at a maximum concentration of less than about 1,200 ppmw, ii) sodium at a concentration of less than about 30,000 ppmw, iii) potassium at a concentration of less than about 20,000 ppmw, iv) magnesium at a concentration of less than about 4,000 ppmw, v) calcium at a concentration of less than about 2,000 ppmw, vi) boron at a concentration of less than about 2,000 ppmw, or any combination of i)-vi), or any individual value or sub-range within these ranges.

[0007] In at least one embodiment, the solvent comprises ammonium chloride, a conjugate base of ammonium chloride, a conjugate used to neutralize an acid generated during solvent extraction, or combinations of any two or more thereof. In various embodiments, the solvent comprises water, an acid, an organic solvent, or a combination of any two or more thereof.

[0008] In one or more embodiments, the raffinate further includes an extractant. The extractant may be in trace amounts, or in an amount of about 1 ppm to about 1,000 ppm, or any individual value or sub-range within this range. In some embodiments, the extractant may be present at a concentration of about 0.05 M to about the molarity of a neat solution based on the total volume of the raffinate composition, or any individual value or sub-range within this range. Suitable extractants are selective for trivalent cations, divalent cations, monovalent cations, or combinations thereof. In some embodiments, i) the trivalent cations comprise boron, ii) the divalent cations comprise calcium, magnesium, or combinations thereof, and/or iii) the monovalent cations comprise lithium, sodium, potassium, or combinations thereof. The extractant may be capable of extracting an alkali metal.

[0009] According to various embodiments, the extractant is an organic compound comprising one or more anionic functional groups, one or more neutral functional groups, or combinations thereof. In some embodiments, the extractant is a neutral reagent comprising functional groups having a dipole moment. In one or more embodiments, the extractant is a negatively charged extractant that has been activated by removing a proton. [0010] According to various embodiments, further disclosed herein are systems for recovering a metal from an aqueous solution, comprising an adsorption system comprising an adsorbent that is selective for a target metal, wherein the adsorption system comprises an inlet for an aqueous solution comprising a plurality of metals at least one of which is the target metal; and a solvent extraction system in fluid communication with the adsorption system, wherein the solvent extraction system comprises an inlet for an eluate from the adsorption system, and an outlet in fluid communication with the inlet of the adsorption system.

[0011] According to various embodiments, the adsorption system is a fixed bed adsorber, a fluidized-bed adsorber, a pond adsorber, a simulated moving bed adsorber, a fluidized bed adsorber, or a column adsorber. The adsorbent may be supported on a substrate and/or may be in the form of sub-units, particles, granules, spheres, microspheres, extrudates, tablets, nanotubes, plate, resin, or a combination of any two or more thereof. In one or more embodiments, the adsorbent comprises aluminum trihydroxide, boron trihydroxide, chromium trihydroxide, molybdenum trihydroxide, lanthanum trihydroxide, rhodium trihydroxide, thulium trihydroxide, zeolite molecular sieve, date pits impregnated with cellulose nanocrystals and ionic liquid, functionalized titanate nanotubes, polymeric porous microspheres with crown ether, granulated chitosan-lithium manganese oxide, manganese-based spinel compounds, modified activated carbon with multiple MnCh nanocomposite ratios, natural and/or synthetic zeolites applying poly(acrylic acid), MnO2-0.4H2O ion sieve, 1 D LiMn2O4 nanorods, nano-lithium ion sieves, intercalated compositions thereof, or combinations of any two or more thereof. According to various embodiments, suitable adsorbents are selective for lithium.

[0012] According to various embodiments, the solvent extraction system comprises an extractant selective for one or more metals. For example, the extractant may be selective for calcium, magnesium, or both. In some embodiments, the extractant is selective for lithium. According to various embodiments, the solvent extraction system (e.g., containing two SX stages) may include a first extractant selective for calcium and magnesium, and a second extractant selective for lithium. In various embodiments, the solvent extraction system forms a raffinate depleted of the target metal, and returns the raffinate to the inlet of the adsorption system. In at least one embodiment, the solvent extraction system includes a separator configured to receive a raffinate depleted of the target metal and remove organic compounds from the raffinate to form a return solution configured to flow through the outlet to the inlet of the adsorption system. The separator may be a retention pond, a flotation oil water separator, a centrifugal oil water separator, a coagulation system, a chemisorption system, or a combination of any two or more thereof.

[0013] Systems described herein may include an ion removal system for removing one or more impurity metals from a return solution of the solvent extraction system. Suitable ion removal systems include, but are not limited to, a reverse osmosis system, an ion exchange system, another solvent extraction system, an electrodialysis system, an evaporation system, a crystallization system, or a combination thereof.

[0014] Further described herein according to embodiments are methods of recovering a metal from an aqueous solution, comprising adsorbing a target metal, from the aqueous solution comprising a plurality of metals, onto an adsorbent that is selective for the target metal; eluting the adsorbent to form an aqueous eluate comprising the target metal; contacting the aqueous eluate with an organic phase in a solvent extraction system to extract the target metal into the organic phase and form a raffinate comprising the aqueous eluate depleted of the target metal; and returning the raffinate to the adsorption system. [0015] The adsorbent used in the methods may be supported on a substrate and/or may be in the form of sub-units, particles, granules, spheres, microspheres, extrudates, tablets, nanotubes, plate, resin, or a combination of any two or more thereof. According to various embodiments, the adsorbent comprises aluminum trihydroxide, boron trihydroxide, chromium trihydroxide, molybdenum trihydroxide, lanthanum trihydroxide, rhodium trihydroxide, thulium trihydroxide, zeolite molecular sieve, date pits impregnated with cellulose nanocrystals and ionic liquid, functionalized titanate nanotubes, polymeric porous microspheres with crown ether, granulated chitosan-lithium manganese oxide, manganese-based spinel compounds, modified activated carbon with multiple MnCh nanocomposite ratios, natural and/or synthetic zeolites applying poly(acrylic acid), M11O2-O.4H2O ion sieve, 1 D LiMn2O4 nanorods, nano-lithium ion sieves, intercalated compositions thereof, or combinations of any two or more thereof. In some embodiments, the adsorbent is selective for lithium.

[0016] According to various embodiments, the solvent extraction system used in the methods includes an extractant selective for one or more metals. In some embodiments, the extractant is selective for calcium, magnesium, or both. In some embodiments, the extractant is selective for lithium. The solvent extraction system may include first and second stages (i.e., two solvent extraction systems in series). The first stage containing a first extractant selective for calcium and magnesium, and the second stage containing a second extractant selective for lithium.

[0017] The methods may include separating entrained organic compounds from the raffinate before returning the raffinate to the adsorption system. The separating may be in a retention pond, a flotation oil water separator, a centrifugal oil water separator, a coagulation system, a chemisorption system, or a combination of any two or more thereof. [0018] According to various embodiments, the methods further include removing one or more impurity metal from the raffinate using an ion removal system. Suitable ion removal systems include, but are not limited to, a reverse osmosis system, an ion exchange system, another solvent extraction system, an electrodialysis system, an evaporation system, a crystallization system, or a combination thereof.

SUMMARY OF THE DRAWINGS

[0019] 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.

[0020] FIG. 1 shows a schematic of a direct lithium extraction process.

[0021] FIG. 2 shows an exemplary system for recovery of lithium from a brine according to embodiments herein.

[0022] FIG. 3 shows another embodiment of a system for recovery of lithium from a brine including flash cooling of the eluate when handling geothermal brines.

[0023] FIG. 4 shows another embodiment of a system for recovery of lithium from a brine that is a zero- or near-zero water process.

[0024] FIG. 5 shows another embodiment of a system for recovery of lithium from a brine including a zero-acid process that produces a LiOH product.

[0025] FIG. 6 shows the cumulative amount of lithium as a function of the cumulative volume during elution of an adsorbent loaded with lithium. Definitions

[0026] 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.

[0027] 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.

[0028] 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 making the 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.

[0029] 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 may 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 may also be expressed as “about 10 or less.”

[0030] 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.

[0031] 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).

[0032] 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.

[0033] The term “metal” or “metals” as used herein refers to the recited metal element and includes compounds (other than salts) containing the metal, salts containing the metal and/or combinations thereof. For example, “lithium” refers to lithium compounds, lithium salts and/or lithi urncontaining molecules. The term “one or more target metals,” which is sometimes used alone for brevity and readability, refers to one or more target metals, compounds thereof, salts thereof, or combinations thereof. For example, lithium, lithium ions, lithium carbonate and/or mixtures of two or more of the foregoing.

[0034] Reference throughout this specification to a chemical element or “metal” refers to compounds, salts and molecules containing the chemical element or metal. For example, “lithium” refers to lithium compounds, lithium salts and lithium-containing molecules. DETAILED DESCRIPTION

[0035] 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 may, 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.

[0036] As lithium has gained importance as an element for use in various applications, research has been conducted to develop simple and inexpensive methods for the recovery thereof. Increased demand of lithium for use in batteries also has driven improvements in the extraction of metals from brines. Two- and three-layer lithium aluminates have been developed for the recovery of lithium from brines. Conventional packed columns for the recovery of lithium have short lifetimes due to the slow deterioration and disintegration of the adsorbent particles.

[0037] According to embodiments, there are various considerations for the first unit operation in a series of operations for removing one or more target metal ion from an aqueous solution including, but not limited to: 1) it cost effectively separates the one or more target metal ion from one or more other ions (e.g., cations) in solution; 2) it sends a solution to a second, downstream operation where the target metal is concentrated at a very high selectivity; and 3) the first process operation reuses, to some extent, a solution from the second operation after the second operation has processed the upstream solution.

[0038] Disclosed herein are systems, methods and compositions for the selective recovery of one or more target metals, such as lithium, from metal containing brines that are easy to use, have a high capacity for the recovery of lithium, and have a long service life. Systems for recovering a metal (e.g., lithium) from an aqueous solution, according to embodiments herein, include an adsorption operation and a solvent extraction operation. Processing operations may be combined to selectively isolate one or more metal from a raw brine solution, then concentrate and optionally convert the one or more metal to a more valuable product (e.g., lithium hydroxide). In one or more embodiments, the target metal is lithium, calcium, magnesium, sulfur, boron, sodium and/or potassium. The described systems, compositions and methods also may reuse solvents (e.g., water, acid, organic solvent, etc.) within one or more unit operations.

[0039] The described embodiments are cost effective and address various environmental concerns including water usage. Embodiments described herein may include an adsorption system, for example, an ion adsorption (IX) system, and solvent extraction system (SX) to selectively isolate and concentrate metal ions, for example, in the case of lithium, as either lithium sulfate or lithium chloride. Further processing may be conducted to convert the metal chloride or sulfate salts to a hydroxide salt such as lithium hydroxide. In one or more embodiments, the raffinate from the solvent extraction system may be recycled and reused in the same or another unit operation.

[0040] In some embodiments, systems for recovering a target metal from an aqueous metal solution (e.g., a brine) include an adsorption system and a solvent extraction system downstream from the adsorption system. Suitable adsorption systems include one or more adsorbent media (also referred to herein as an “adsorbent” or “adsorption material”) contained within a housing, pond, column(s), bed(s) and/or packed bed(s).

[0041] Adsorption, such as ion exchange, intercalation, and/or physical/chemical adsorption, is suitable to capture one or more target metals (e.g., lithium) from a solution. The aqueous feed solutions to adsorption operations according to embodiments herein may contain the one or more target metal (e.g., lithium) at a concentration of less than about 100 ppm, less than about 500 ppm, greater than about 2,000 ppm, about 100 ppm to about 5,000 ppm, or any individual value or subrange within these ranges. In some embodiments, suitable concentrations of the one or more target metals are dependent on the concentration of the one or more target metals (e.g., lithium) in the brine as well as the concentration of potentially interfering species (e.g., impurity metals), such as magnesium (Mg), calcium (Ca), and boron (B). If the concentration of the one or more target metals is low (e.g., less than about 100 ppm) and the concentration of one or more impurity metals is substantially higher, the brine may require a pre-treatment step (e.g., adsorption or solvent extraction) to reduce the concentration of impurity metals in the feed solution.

[0042] The adsorption operation employs an adsorbent material that selectively adsorbs the one or more target metals onto the material. In at least one embodiment, the adsorption media is selective for one or more metals in an aqueous metal solution. For example, the adsorption media may intercalate lithium compared to other ions at a ratio of 10: 1, that is, the adsorption media may comprise a resin that intercalates at least 10 lithium ions for every one non-lithium cation. The adsorption media may be in the form of sub-units, particles, granules, spheres, microspheres, extrudates, tablets, nanotubes, plates, resin or combinations of any two or more thereof. Suitable adsorption materials include, but are not limited to, aluminum trihydroxide, boron trihydroxide, chromium trihydroxide, molybdenum trihydroxide, lanthanum trihydroxide, rhodium trihydroxide, thulium trihydroxide, zeolite molecular sieve, date pits impregnated with cellulose nanocrystals and ionic liquid, functionalized titanate nanotubes, polymeric porous microspheres with crown ether, granulated chitosan-lithium manganese oxide, manganese-based spinel compounds, modified activated carbon with multiple MnCh nanocomposite ratios, natural and/or synthetic zeolites applying poly(acrylic acid), MnCh-O.dFFO ion sieve, 1 D LiM C nanorods, nano-lithium ion sieves, intercalated compositions thereof, or combinations of any two or more thereof.

[0043] The adsorbent may be supported on a variety of substrates. Suitable substrates may be in the form of sub-units, particles, granules, spheres, microspheres, extrudates, tablets, nanotubes, plates, or any combination thereof. Suitable support materials include, but are not limited to, carbon, a polymeric material, silica, alumina, or combinations of any two or more thereof. Substrates such as polymer beads may withstand high temperature aqueous solutions (e.g., >32°C, >65°C) without becoming friable. In some embodiments, the adsorbent is an intercalated aluminum tri-hydroxide. The adsorbent is chosen to have a high selectively for the one or more target metals (e.g., lithium). The selectivity for the one or more target metal (e.g., lithium) is suitably greater than about 5: 1 absolute relative to other ions, especially other cations, or any individual value or sub -range within this range.

[0044] According to one or more embodiments, the adsorbent is supported on one or more substrates including, but not limited to, carbon particles, polymer beads, silica particles, alumina particles, or combinations of any two or more thereof. In some embodiments, when the target metal containing aqueous solution is a geothermal brine, an adsorbent is employed that withstands temperatures from 65-100°C (e.g., a thermally stable intercalated aluminum tri-hydroxide). In various embodiments, the thermally stable intercalated aluminum tri-hydroxide adsorbent is supported on polymer beads, which function in high temperature aqueous solutions without becoming friable.

[0045] Notably, about 75-80% of lithium chloride and lithium carbonate, and their derivatives, are currently produced from the recovery of lithium from brines, via natural evaporative processes. Geothermal brines are of particular interest for a variety of reasons. First, some geothermal brines provide a source of electrical power resulting from hot geothermal pools stored at high pressure underground that, when released to atmospheric pressure, provide flash-steam. The flash-steam may be used, for example, to run a powerplant. In some geothermal waters and brines, associated binary processes may be used to heat a second fluid that provides steam for the generation of electricity without the flashing of the geothermal brine. Additionally, geothermal brines contain various useful elements that may be recovered and utilized for secondary processes.

[0046] Geothermal brines include various metals (e.g., metal ions) including alkali and alkaline earth metals, along with other metals such as lead, silver and zinc, at varying concentrations, depending on the source of the brine. Recovery of such metals may be useful in the chemical and pharmaceutical industries. Conventionally, the economic recovery of metals from natural brines, which may vary widely in composition, depends not only on the specific concentration of the desired metal, but also upon the concentrations of interfering species, particularly silica, calcium and magnesium, because the presence of the interfering species will increase recovery costs as additional steps must be taken to remove the interfering species.

[0047] In various embodiments, adsorbents for use in systems, apparatus and methods described herein, may be contained in a fixed bed. An advantage of using a fixed bed process is the relatively inexpensive equipment and the simplicity of the process. In processes involving large volumes of a dilute solution, a Simulated Moving Bed (SMB) system may provide better performance than cycled fixed-bed systems.

[0048] To desorb the one or more target metals from the loaded adsorbent and regenerate the adsorbent material, an eluent is passed through the material. Suitable eluents are aqueous solvents such as water-based solutions containing one or more metals such as lithium, calcium, magnesium, potassium, boron, sodium, etc. The one or more target metals (e.g., lithium) in the eluent may be at a high concentration (e.g., about 100 ppmw to about 1 ,000 ppmw) because when the concentration is too low, an adsorbent material such as aluminum tri-hydroxide may become less stable while the aluminum oxide lattices begins to degrade.

[0049] Conventional adsorption operations for isolating one or more target metals such as lithium utilize a large quantity of water for elution and concentration of the metal (e.g., lithium, lithium salts, etc.). Such operations are further complicated by the use of water extraction and purification systems to supply water for elution, which results in a complex process with numerous steps, a large loss of water, and high power consumption.

[0050] According to embodiments herein, the water extraction and purification equipment may be downsized, replaced, and/or eliminated together with recycling of the aqueous by combining the adsorption operation with one or more downstream solvent extraction operations. Since solvent extraction is typically a proton exchange, the combination with adsorption can reduce the overall acid/base consumption in the solvent extraction process.

[0051] In some embodiments, the eluent used for the adsorbent material is a raffinate stream from a solvent extraction system. In various embodiments, this elution loop, which supplies the aqueous feed to the solvent extraction operation and receives the raffinate stream for elution, is carefully controlled to provide a target concentration (e.g., about 100 ppmw to about 1,000 ppmw) of one or more metal (e.g., lithium) to the loaded adsorbent as eluent. Following desorption of the one or more target metals into the eluent, the resulting eluate containing the dissolved one or more target metals flows to the solvent extraction operation as the aqueous feed.

[0052] The one or more solvent extraction operations in the systems according to embodiments herein are suitable to receive the eluate from the adsorption operation and, in some embodiments, remove impurities such as calcium and magnesium in a first solvent extraction operation, and in a second solvent extraction operation, selectively extract the one or more target metals (e.g., lithium) from any remaining impurities (e.g., sodium, potassium and boron). Once extracted, the one or more target metals (e.g., lithium ions), is concentrated by deactivating the extractant with acid in a fixed volume of water. As the delithiated aqueous solution is recirculated through the elution loop, each pass successively increases the concentration of one or more metals such as lithium (e.g., lithium salts) in the aqueous. This is beneficial not only to elution of the adsorbent, but also ultimately to increase the total recovery of one or more target metals.

[0053] Suitable solvent extraction systems for combination with adsorption operations to selectively extract one or more target metals (e.g., lithium) from an aqueous solution, are dynamic systems of extraction, scrubbing, and stripping stages. Each of these stages receives an aqueous solution and contacts it with an organic solution containing an organic extractant (e.g., a metal ion extracting molecule). The extraction stages extract the one or more target metals from the feed solution. The scrubbing stages reduce transfer of aqueous entrainment and impurities in the organic solution. The stripping stages concentrate the one or more target metals (e.g., metal ions) with the desired counterion (e.g. LiCl or Li2SO4).

[0054] Depending on the pH of the aqueous solution and the pH at which the one or more target metals (e.g., metal ions, lithium, lithium ions, etc.) are extracted, and based on the pH isotherm of the individual extractant, the reaction will proceed according to Equation 1 (using lithium as an example).

Extraction: Ext-H(org) + Li⁺(_aq) Ext-Li(org) + H⁺<_aq) Eq. 1

[0055] If enough acid is produced to stop the extraction, additional base may be added to maintain the extraction reaction. Stripping follows Equation 2.

Stripping: Ext-Li(org) + H⁺(_aq). Ext-H(org) + Li⁺(_aqj Eq. 2 [0056] Stripping is accomplished by using a large excess of acid, which pushes the equilibrium far to the right of Equation 2. In an exemplary embodiment, the anion counterion to the lithium may be chloride or sulfate and is equivalent on the respective sides of the extraction and strip equations.

[0057] The selectivity of solvent extraction for lithium over other cations is very high. The majority of the impurities in the eluent come from the residual interstitial feed solution in the resin. These impurities are removable in a second processing step. Instead of using two operations, one for additional selective separation of lithium and then a water removal and recovery step, solvent extraction may be used to accomplish both. The eluate from the adsorption operation is the feed to the solvent extraction operation. Many solvent extraction reagents have a relatively poor separation of divalent cations from monovalent cations such as lithium. However, the divalent cations may be pre-removed very selectively from the eluate feed followed by an efficient separation of lithium from other monovalent cations. All of this may be accomplished using the same reagent at different pH.

[0058] In various embodiments, the solvent extraction operation may employ an organic solvent to contact the aqueous solution containing the one or more target metals. The organic solvent used in the solvent extraction process may further include an extractant. The extractant is a compound that binds to the one or more target metals, such as lithium. The extractant may then be treated with another compound, such as an acid, a base, or any other ion that causes the release of the target metal. In particular, the extractant may be used to help eliminate boron from the composition. In some embodiments, the extractants used herein may be phosphorus-based extractants. [0059] In some embodiments, if a reusable (or return) solution, for example, exiting the solvent extraction system and returning to the adsorption system, is not optimized, the process receiving the return solution may be less efficient and result in higher operating costs. When one processing step may not adequately utilize a solution returned from another processing step, then it could be costly to modify the return solution for further processing and/or the solution may not be reused increasing environmental waste. One goal of optimization may be to reduce or minimize environmental waste and/or to treat the return stream so that it is suitable for further processing by the same or a different unit operation.

[0060] In some embodiments, at least a small bleed stream of the return solution is treated to reduce impurities before reuse in the same or a different unit operation. In one or more embodiments, a buildup of impurities may occur in the return solution as it cycles through the one or more unit operations. Additional processing such as the bleed stream is one way to minimize additional processing to keep the return solution within favorable specifications. In some embodiments, reduced or minimized additional processing may include treating water (e.g., reverse osmosis, impurity removal, etc.), or bleeding the solution and replacing it with water having no or fewer impurities. The disclosed embodiments are suitable for generating optimized return streams between unit operations (e.g., adsorption and solvent extraction) to ensure the highest performance and efficiency of each unit operation.

[0061] A return solution may be optimized to solve industry problems by analyzing the benefits and limitations of an upstream process and a downstream process. In some embodiments, an optimal return solution is generated by running two processes in such a way that the economic and environmental benefit of both processes is optimized to the fullest potential such that the processes work together in the most efficient manner. There are many different processes that may be used for the initial treatment of an untreated aqueous solution (e.g., a brine). These processes include, but are not limited to, adsorption, adsorption, solvent extraction, membrane separation, electrodialysis, selective chemical precipitation, and so on. Each of these processes has benefits, nonetheless, and can be optimized for efficiency and performance.

[0062] Solutions according to embodiments herein may be returned from one unit operation to the same or a different unit operation (e.g., an upstream operation). The returned solution may be used as a process solution for the unit relevant unit operation, or it may be utilized somewhere else in the system, for example, as process water. This results in a significantly lower environmental impact than conventional processes that typically do not reuse or recycle solutions, such as water. [0063] In one or more embodiments, a solution returned to an upstream process (e.g., the adsorption operation) may be the raffinate of the downstream process (e.g. solvent extraction). The solution received by the downstream process may be altered producing a raffinate solution depleted in one or more metal species. For example, some metal species, such as lithium, may be removed from the solution, while other metal species may be added to the solution, for example, in the case of pH modification. In some embodiments, this raffinate solution may undergo an impurity removal process (e.g. reverse osmosis, etc.) to keep the solution impurities from increasing with each cycle through the upstream and downstream processes.

[0064] Multiple parameters may be considered in the preparation of a composition as an optimal return solution, for example, cation concentration (z.c., lithium, calcium, magnesium, potassium, boron, sodium, etc.), pH, and temperature to name a few. In some embodiments, anion concentration (e.g., halides, sulfate, and nitrate) may be considered. The entire composition of the solution(s) flowing through the system and processes should be taken into consideration as the solution(s) may be reprocessed multiple times and may be used in one or more unit operations. Individual parameters of the solution(s) also may be monitored and controlled to provide cost- effective operations for both processes.

[0065] All of these parameters may be adjusted in such a manner that the impurities in the return solution may be kept at a concentration suitable for use in another unit operation (e.g., an upstream process) with little or no impact to the operation’s performance. The presence of impurities may inhibit the production of a suitable aqueous solution containing a target metal (also referred to as a pregnant leaching solution or “PLS”) for solvent extraction, or may increase the concentration of metal species in the PLS above an optimal range for subsequent processing.

[0066] An optimal return solution, for example, the raffinate of a solvent extraction system returned to an adsorption system for reuse, may have a pH that largely remains constant both during the adsorption operation and the solvent extraction operation. In some embodiments, the pH of the raffinate from a solvent extraction process may be controlled in a range of about 2 to about 11, about 4 to about 9, or any individual value or sub-range within these ranges.

[0067] In one or more embodiments, the raffinate received from the solvent extraction operation has a low concentration of lithium, calcium and/or magnesium. For example, the raffinate composition may include lithium at a concentration of less than about 1,200 ppmw, about 0 ppmw to about 800 ppmw, or any individual value or sub-range within these ranges. In some embodiments, the raffinate composition may include calcium at a concentration of less than about 2,000 ppmw, about 0 ppmw to about 4,000 ppmw, or any individual value or sub-range within this range. In embodiments, the raffinate may contain magnesium at a concentration of less than about 2,000 ppmw, about 0 ppmw to about 4,000 ppmw, or any individual value or sub-range within these ranges. This may be the result of a highly selective extractant for these metals used in the solvent extraction system. [0068] In some embodiments, the optimized return solution may not be dependent on a downstream process yet still in an optimal range for downstream processing. For example, the process downstream may be unlikely to increase the temperature of the raffinate higher than the operating temperature of the upstream process, so that controlling the temperature of the raffinate may not be needed.

[0069] In at least one embodiment, an optimized return solution may be a solvent used in the downstream process that creates an optimized feed solution for a solvent extraction, adsorption and/or electrodialysis system. For example, a solvent extraction system may remove a target metal (e.g., lithium) and/or a majority of the impurities that negatively impact further processing of the solvent from the PLS. In some embodiments, the target metal and/or impurity depleted solution may be used without negative impact as a source of water.

[0070] The ability to reuse a solution, such as a solvent extraction process raffinate, as a water source to the same, a different, an upstream and/or front-end process significantly reduces water consumption of the overall system as compared to conventional direct metal (e.g., lithium) extraction processes. For example, a typical evaporation process uses over 100 m³ water per ton of lithium carbonate equivalent (LCE). Compositions, systems and methods according to embodiments herein may reduce water usage to less than about 75 m³, less than about 70 m³, less than about 65 m³, less than about 60 m³, less than about 55 m³, less than about 50 m³, less than about 20 m³, less than about 10 m³, or any individual value or sub-range within these ranges. Reusing critical solvents may provide a significantly benefit in the operation of metal (e.g., lithium) separation techniques because certain solvents, such as fresh water, are often unavailable. Another benefit of the disclosed systems, compositions and methods is minimizing or eliminating further processing of enormous amounts of industrial water contaminated with impurity ions. [0071] In one or more embodiments, an optimized return solution is one where a solvent extraction system creates an optimized feed solution for an upstream adsorption system. In this embodiment, the adsorption system is capable of operating within a certain concentration of impurities, thus, the composition range of impurities of the raffinate may be determined and controlled.

[0072] An example of an ideal solution is one where a membrane system is the upstream process. In this example a membrane system is used to reduce the impurities in the PLS used for solvent extraction. The target metal depleted solution exiting the solvent extraction system may then be returned to the membrane operation for reuse.

[0073] In some embodiments, a first solvent extraction system may be used to create an optimized feed solution for a second solvent extraction system. In this embodiment, two different solvent extraction systems are used in series. The first solvent extraction system may remove impurities (e.g., magnesium and calcium) from the target metal (e.g., lithium) and then transfer the purified solution containing the target metal to a second solvent extraction system that selectively extracts the target metal from any remaining metals. The target metal depleted solution may be returned to the first solvent extraction process for reuse or returned to the aqueous metal solution reservoir.

[0074] In another embodiment, an optimized return solution such as a raffinate from a solvent extraction system is fed to a membrane system for reuse. In this embodiment, the solvent extraction system is used to remove or reduce metal impurities that negatively impact membrane processing. The solvent extraction system may be operated in such a way that the solution leaving the solvent extraction system may be sent through a membrane for cheaper production of the target metal. The depleted target metal solution may then be returned to solvent extraction system for reuse. [0075] FIG. 1 shows an embodiment of a system 100 for recovering a target metal (e g., lithium) from an aqueous metal solution (e.g., a brine) including several unit operations (e.g., direct lithium extraction operations) in series. In one or more embodiments, systems as described herein may include two or more of the described unit operations. Exemplary system 100 includes an adsorption system 102, a solvent extraction system 104, a bipolar electrodialysis (BPD) system 106, and a crystallization system 108. The solution 110 exiting adsorption operation 102 may be an optimized intermediate solution and enters solvent extraction operation 104. Following solvent extraction 104, an optimized return solution 112, for example, a target metal or impurity metal depleted solution, may return to adsorption operation 102 for reuse. Although depicted in FIG. 1 as returning to the adsorption operation 102 for reuse, it should be appreciated that optimized return solution 112 may flow to any suitable unit operation for reuse.

[0076] As shown in FIG. 1, an organic metal solution 114 exiting solvent extraction operation 104 may flow to the BPD system 106 for processing. An optimized return solution, for example, a target metal depleted solution 116, may return to solvent extraction system 104 for reuse, while the target metal rich solution 118 may flow to crystallization system 108. Following processing in the crystallization system 108, target metal rich product stream 124 exits crystallization system 108.

[0077] Solutions 112, 116 and 122 returned from operations 102, 104 and 106 may be optimized return solutions suitable for reuse in one or more suitable unit operation. Reusing these streams reduces environmental waste and cost as compared to conventional direct metal (e.g., Li) extraction processes. Other embodiments of system 100 include any two or more of the disclosed unit operations, for example, an adsorption system 102 upstream from a solvent extraction system 104 or two adsorption systems and two solvent extraction systems. [0078] According to various embodiments, once a target metal such as lithium is recovered from an eluate solution (e.g., a lithium brine, the eluate from an adsorption operation, etc.) during a solvent extraction operation, the raffinate (i.e., an aqueous stream, water, containing one or more target metal and optionally a small amount of extractant) may be reused in the upstream process. Reusing the raffinate dramatically reduces water consumption of the system. In some embodiments, the raffinate solution may only be used, for example in an adsorption operation, if the return solution does not contain concentrations of salts that inhibit the unit operation receiving the solution. For example, in the case of lithium adsorption, the presence of cations in solution may result in poor elution of lithium from the adsorbent.

[0079] In one or more embodiments, the raffinate solution from a solvent extraction operation is treated to remove one or more organic compound entrained within the aqueous phase to form an optimized return solution. This may be accomplished in a variety of ways including a retention pond, oil water separator (e.g., flotation, centrifugal, etc.) or chemisorption system. The organic free aqueous solution may then be treated to reduce the concentration of cations in solution to meet the specifications set forth in Table 1. In some embodiments, the concentrations of metal ions in Table 1 are not absolute limits, but approximate ranges. A unit operation, for example, an adsorption operation, may be suitable to tolerate a maximum metal ion concentration as set forth in Table 2.

Table 1 - Specifications for return solution from Solvent Extraction to Adsorption.

Table 2 - Max metal concentrations for return solution from Solvent Extraction to

Adsorption

[0080] Magnesium, calcium, and lithium often are target metals removed during adsorption, solvent extraction and/or in another operation, so metal depleted streams from such operations will contain these metals in low concentrations. Other metals such as sodium, potassium and/or boron or an ammonium chloride and/or any conjugate base of an acid used to neutralize the acid generated in solvent extraction may be present in the metal depleted streams depending on the base used to neutralize the acid formed as part of the unit operation (e.g., solvent extraction). These other (non-target) metals may build up in the recycled solution over time. In some embodiments, an ion removal system such as reverse osmosis, ion exchange, etc. may be used to reduce and/or control the concentration of non-target metal cations in returns and/or recycled solutions.

[0081] In one or more embodiments, when adsorption is used in an upstream process, a target metal (e.g., lithium) in the raffinate of a downstream solvent extraction system may support the elution of the target metal during the upstream process. In some embodiments, the raffinate and/or return solution may contain about 1 ppmw to about 1000 ppmw, about 25 ppmw to about 500 ppmw, about 50 ppmw to about 100 ppmw, or any individual value or sub-range within these ranges, of the target metal to enhance performance of another unit operation such as adsorption. In one or more embodiments, the presence of magnesium and/or calcium in the return solution may have almost no direct effect on elution; however, the presence of calcium or magnesium may result in an eluate that is not usable by a downstream process. In some embodiments, boron is not a target metal extracted during a unit operation, but as the return solution is recycled, the concentration of boron may continue to increase until the return solution becomes unsuitable for use in the same or a different unit operation. In some embodiments, when adsorbing lithium in an adsorption system, the presence of sodium and potassium may inhibit elution. As the cation concentration increases, lithium elution may be slowed. For concentrations of sodium and potassium below 20,000 ppmw, there is no substantial adverse effect on elution. If the concentrations of metals in the return solution are maintained within the approximate ranges shown in in Table 1, the raffinate solution of a solvent extraction system is suitable to elute an upstream adsorption process and keep water consumption to a minimum.

[0082] Systems as described herein may include an adsorption system (upstream) as described herein in fluid communication with a solvent extraction system (downstream). The adsorption system includes an adsorbent according to various embodiments described herein that is selective for the target metal. An aqueous solution (e.g., a brine) containing a plurality of metals, at least one of which is the target metal (e.g., Li), is received at an inlet of the adsorption system.

[0083] A target metal depleted aqueous solution exiting through an outlet of the adsorption system may flow into an inlet of the solvent extraction system. Solvent extraction relies on the mass transfer of metals across an organic/aqueous solvent interface. Increasing the interfacial surface area also increases the rate at which the metal is transferred. This is because the extractant and the metal being extracted come into contact at the interface. An increased surface area is produced by breaking the initial interface and then breaking up droplets produced by the mixer. The continuous shearing of droplets using an agitator (e.g., a mixer, impeller, pump, etc.), results in smaller droplets and a shift in the distribution of droplet size. Increasing the speed of the agitator, and therefore shear, increases the surface area of the emulsion. In solvent extraction systems, there is a continuous phase where the solution is contiguous and a droplet phase. The continuous phase is often the phase with the greater volume in the mixer (e.g., if the aqueous volume is in excess, it is often the case that the aqueous will be the continuous phase and the organic will be mostly composed of organic droplets).

[0084] The organic phase may include an organic extractant that is selective for one or more target metals. The target metal will transfer from the aqueous phase to the organic phase leaving behind other metals thereby isolating the target metal from the other metals. In some embodiments, the extractant is selective for calcium, magnesium, or both. In other embodiments, the extractant is selective for lithium. Suitable solvent extraction reagents for extracting metals (e.g., alkali metals, lithium, etc.) may have anionic functional groups, neutral functional groups, or combinations thereof. In some embodiments, neutral reagents have a substantial dipole moment for their functional groups - the more negative the functional group, the more aggressive the attraction to cations. Charged extractants may be activated by removing a proton, which leads to a fixed negative charge. The pKa at which this occurs may be different for each extractant and is dependent on the acidity of the proton. This may be affected by the stability of the metal complex. The metal being extracted will affect how easily the proton is removed. The pH at which the extractant is activated for an ion may be dependent on the complex being formed. In some embodiments, the extractant is a neutral reagent comprising functional groups having a dipole moment, for example, a dipole moment that is strong enough to create bonding with a lithium chloride or lithium sulfate salt.

[0085] In some embodiments, the solvent extraction system includes stages where the aqueous phase contacts the organic phase. In the first stage, the organic phase may include a first extractant selective for calcium and magnesium, and in the second stage, the organic phase may include a second extractant selective for lithium. In some embodiments, the raffinate depleted of calcium and magnesium flows from the first stage into the second stage. In the second stage, lithium is further removed and the raffinate exiting the second stage is depleted in calcium, magnesium and lithium. This second stage raffinate may be scrubbed and stripped to remove entrained organic phase from the aqueous raffinate and then returned to another operation (e.g., the adsorption system) for reuse.

[0086] Despite scrubbing, raffinate streams from the one or more solvent extraction systems may nonetheless contain an amount of extractant therein. For example, the amount of extractant in a raffinate stream may be a trace amount, or about 1 ppm to about 1000 ppm, or any individual value or sub-range within these ranges. The extractant may be any suitable extractant for solvent extraction according to one or more embodiments described herein including organic extractants. [0087] In one or more embodiments, the solvent extraction system further includes a separator as described herein. The separator may have an inlet in fluid communication with an outlet of the solvent extraction stage to receive the raffinate depleted of the one or more target metals. The separator may remove entrained organic phase from the aqueous phase of the raffinate forming an aqueous return solution suitable for use as a solvent in another unit operation such as adsorption.

[0088] An exemplary system 200 for recovering lithium from a brine is shown in FIG. 2. The system 200 includes a fixed-bed adsorption process 202 (Adsorption Unit) upstream from a solvent extraction unit 204, most of the Lithium-Containing Brine 206 (Feed Brine) passes through the Adsorption Bed 202 and immediately out as Delithiated Brine 208 (Effluent Brine). The lithium and a few other cations along with the corresponding counterions are retained in the Adsorption Bed 202.

[0089] Following washing of the adsorption bed 202 to remove residual Feed Brine, for example, with air, lithium along with a few minor cations are then eluted form the Adsorption Bed 202 using an eluent 212, and the Eluate 214 is fed into Solvent Extraction 204. The Eluate stream 214 is usually smaller and purer in lithium than the Feed Brine 210. Thus, Solvent Extraction 204 requires fewer scrubbing and extraction stages than without the Adsorption Bed 202. Also, because the Eluate 214 is purer, the Raffinate 220 from the Solvent Extraction Process 204 is generally pure enough to be used as the Wash and/or eluent for the Adsorption Bed 202. This reduces water consumption considerably. Acid 216 may be introduced into the solvent extraction 204 unit, for example, for pH adjustment and/or to reactivate a deactivated extractant. The resulting purified lithium-containing brine (extract) 218 exits the solvent extraction system as a product stream.

[0090] Many variations of the above system are possible depending on the objectives of the operator, the site conditions, and regulatory considerations. An exemplary embodiment of a system for recovery of lithium from a brine includes flash cooling of the Eluate 314 when handling geothermal brines 310 is shown in FIG 3. For instance, as shown in FIG. 3, if a hot geothermal brine 310 needs to be processed in a system 300 according to embodiments herein, the Eluate 314 from Adsorption 302 can be partially flashed 322 to cool the Eluate 324 before it enters Solvent Extraction 304. This might be desirable to keep the vapor pressure of the diluent used for Solvent Extraction 304 below its flash point. The steam 326 from the partially flashed Eluate 314 can be condensed to provide water for elution 320, be used in multistage flash for greater water recovery, or be reinjected into the wash or Effluent Brine to reheat it prior to reinjection.

[0091] In areas where water is extremely scarce, other elaborations can be made to further reduce water usage. For instance, the residual feed brine, the residual wash, and the residual eluate in the Adsorption Bed may be blown out with a gas such as air. This segregates the concentrated Feed Brine from the less concentrated Wash, and the Wash from the Eluent. Thus, the amount of Wash and Eluent is reduced. Since the Wash is low in total dissolved solids (TDS), it can be concentrated by Electrodialysis, Reverse Osmosis, Multistage Flash, or combinations thereof, depending on the availability of steam, natural gas, or electricity.

[0092] An exemplary embodiment of a system 400 for recovery of lithium from a brine that is a zero- or near-zero water process is shown in FIG. 4. The freshwater 426 produced from desalination processes (e.g., knockout pots 428, electrodialysis 430, etc.) can be used to reduce the amount of eluent needed. Electrodialysis with reversal (EDR) is one technology utilized to selectively transport monovalent metal ions (e.g., lithium or sodium) through ion exchange membranes to remove multivalent contaminants (e.g., calcium and magnesium). EDR is an ion exchange membrane technology that transfers salts through ion exchange membranes using DC power, rather than pressure like other membrane separations. The “reversal” step involves reversing the direction of electricity flow in the stack to complete a self-cleaning step that removes scaling from the surface of the membranes. If the incentive is high enough, the washate 432 can be concentrated 434 in a multistage flash unit 436 to near saturation and essentially all the fresh water would be recovered.

[0093] FIG. 5 shows one embodiment of a zero-acid process that produces a LiOH product. In this embodiment, the adsorption-solvent extraction process 500 produces the desired acids on site by means of Bipolar Electrodialysis 519 (Salt Splitting). In addition to producing acid for Solvent Extraction 504, Bipolar Electrodialysis 519 is also suitable to produce an aqueous LiOH product 525, which may be crystallized and dried 523, 527.

[0094] Notably, Bipolar ED (BPED) and EDR are related technologies that transfer salt using ion exchange membranes but also uses a unique membrane called a bipolar membrane that splits salt water into acid and caustic products. Both technologies operate using a stack of membranes and spacers enclosed between assemblies which contain electrodes. EDR is typically operated with two process streams, where salt is transferred from one to the other. In BPED, for production of strong acids and bases, there are three process streams: a brine stream that is diluted, a caustic product stream, and an acid product stream. The nature of these two processes means that hardware for building these stacks is exclusive to one or the other, but not both. Conventional stack arrangements for ED systems are expensive, inflexible in design (particularly for BPED), tend to leak, and/or are not scalable to commercial-size. Generally, customers desire the ability to jump rapidly from a pilot or demo scale to a commercial -level system, and stack arrangements typically do not offer an easy route to such scalability.

[0095] As can be appreciated by those skilled in the art, the Adsorption-Solvent Extraction Processes for recovery of lithium from brines according to embodiments herein are very flexible. By combining two or more of the above variations or others that are apparent to those skilled in the art, it is possible to process virtually any brine, at any location, with or without acid, and with or without water.

[0096] In various embodiments, solvent extraction units 204, 304, 404, 504 may be comprised of a standard solvent extraction system using an extractant in an organic diluent that is mixed with the eluent in order to extract the one or more target metal (e.g., lithium) selectively. Suitable extractants as described herein undergo a proton exchange. The extraction process liberates a proton from the extractant which acidifies the raffinate and the target metal (e.g., lithium) is loaded into the organic. The organic is then separated from the aqueous and sent to another mixer where an acidic solution is used to deactivate the extractant which releases the target metal. In other cases, the solvent extraction system does not require acid. Release of the Li from the extractant may be accomplished by thermal swing or by contacting with water.

[0097] Further described herein according to various embodiments is an apparatus for the preparation of a purified target metal solution. The apparatus may include an adsorption chamber, wherein the adsorption chamber comprises one or more adsorption materials as described herein. In some embodiments, the apparatus further includes an extraction chamber, wherein the extraction chamber is in fluid communication with the adsorption chamber. The adsorption chamber includes an inlet portal to allow the introduction of a fluid and the extraction chamber comprises an outlet portal to produce to the purified target metal solution.

[0098] In one or more embodiments, the apparatus further includes a flashing component between the adsorption chamber and the extraction chamber. In some embodiments, the flashing component includes a system to transfer the heat energy to the adsorption chamber or the inlet portal to the adsorption chamber. In one or more embodiments, the apparatus further includes a linkage between the extraction chamber and the adsorption chamber allowing the return of a solution depleted between the target metal from the extraction chamber to the adsorption chamber. In some embodiments, the disclosure describes the extraction chamber further comprises an inlet for introduction an acid or an acidic solution. In various embodiments, the adsorption chamber further includes an apparatus to recycle water from the system. [0099] Further disclosed herein are embodiments of methods for recovering a metal from an aqueous solution. The methods may include adsorbing a target metal, from the aqueous solution comprising a plurality of metals, onto an adsorbent that is selective for the target metal. The adsorption may occur within an adsorption system as described herein. The adsorption system contains the adsorbent, which contacts the aqueous solution containing the target metal. The target metal adsorbs onto the adsorbent, which may be intercalated to provide stronger physisorption of the target metal. The lithium and chloride counterion are able to occupy void spaces in the crystal matrix of the aluminum oxide solid structure. In some embodiments, the matrix is a sodium chloride crystal having different orientation and bonding. In embodiments, the matrix may be a three dimensional superstructure like the framework of a high rise. The occupying of void spaces may be referred to as intercalation. Ions such as Na, Mg, Ca and K are unable to easily fit into the void spaces of the matrix and thus, intercalate very little (e.g., about 20-150 lithium atoms to one non-lithium ion). These other ions, even if not intercalated, are attracted to the surface charge of the aluminum oxide material. In one or more embodiments, the target metal depleted aqueous solution may flow from the adsorption system via an outlet and into the inlet of a solvent extraction system where a target metal is extracted as described herein above.

[0100] Methods according to embodiments herein may further include eluting the adsorbent to form an aqueous eluate containing the target metal at a high concentration. In some embodiments, an aqueous solvent flows through the adsorption system and the adsorbed target metals release and dissolve into the solvent. In further embodiments, the methods include contacting the aqueous eluate with the organic phase of a solvent extraction system. The target metal is extracted into the organic phase and recovered. As in all solvent extraction processes, the extracted ions are stripped into a rich electrolyte solution. When zwitterionic extractants are used, an aqueous strip solution may be used and for standard extractants, an acid (to strip the lithium) may be used. The aqueous raffinate formed during solvent extraction includes the aqueous eluate depleted of the target metal. This raffinate may be recycled to the adsorption system or another unit operation for reuse.

[0101] In one or more embodiments, the methods include extracting magnesium and/or calcium from the aqueous solution in a first stage of the solvent extraction system and extracting lithium from the magnesium and/or calcium depleted aqueous in a second stage of the solvent extraction system. The extractant used in the organic phase of the first stage of solvent extraction may be selective for calcium and/or magnesium and the extractant used in the organic phase of the second stage of solvent extraction may be selective for lithium.

[0102] Methods according to embodiments herein further may include separating entrained organic phase from the aqueous phase in the raffinate. This separating process may be conducted in a retention pond, a flotation oil water separator, a centrifugal oil water separator, a chemisorption system, or a combination of any two or more thereof.

[0103] In one or more embodiments, the methods may include removing one or more impurity metal from the raffinate using an ion removal system. Suitable ion removal systems include, but are not limited to, a reverse osmosis system, an ion exchange system, or a combination thereof.

In some embodiments, the present disclosure relates to a method of removing one or more impurities from a metal solution including contacting the metal solution with an adsorption material, wherein the adsorption material binds to one or more impurities to obtain a first processed metal solution; extracting the first processed metal solution with a second solvent to obtain a purified metal solution. In some embodiments, the purified metal solution contains either a higher weight percentage of the target metal than the metal solution, and/or a lower weight percentage of one or more impurities than the metal solution. [0104] In some embodiments, the metal solution is a brine, such as a geothermal brine. In some embodiments, the brine is seawater. In other embodiments, the brine is a byproduct of an industrial process. In some embodiments, the metal solution contains at least 1 ppm of the target metal. In some embodiments, the metal solution contains at least 10 ppm of the target metal. In some embodiments, the target metal is lithium. The adsorption material may be selective for one or more cations, such as a divalent cation. In some embodiments, the cation is a magnesium cation or a calcium cation. In various embodiments, the adsorption material is selective for calcium and magnesium cations.

[0105] According to one or more embodiments, the first processed metal solution has a reduced concentration of one or more cations, such as magnesium cations or calcium cations. The reduced concentration of the one or more cations may be a reduced concentration of calcium and magnesium cations. In various embodiments, the reduced concentration of one or more cations results in a reduction of the one or more cations of at least about 10%, at least about 25%, at least 50%, or any individual value or sub-range within these ranges.

[0106] In some embodiments, the methods further include employing an extractant suitable to bind to one or more target metals. The second solvent may be an organic solvent and the extractant may be an organic molecule. In one or more embodiments, the extractant does not bind to one or more impurities, such as boron. In at least one embodiment, the first processed metal solution contains at least about 10% less of one or more impurities, at least about 25% less of one or more impurities, at least about 50% less of one or more impurities, or any individual value or sub-range within these ranges.

[0107] In various embodiments, the adsorption material is received in a bed and/or column. In some embodiments, the adsorption material is affixed to the bed. In one or more embodiments, the bed has a mass transfer zone that is longer than the size of the bed. The adsorption material may be an aluminum-based material such as aluminum trihydroxide.

[0108] According to one or more embodiments, the adsorption material further includes a polymer. In at least one embodiment, the adsorption material is supported on the polymer. In various embodiments, the method results in a selectivity of the target metal relative to boron of at least 6.

[0109] Methods according to embodiments herein provide a selectivity of the one or target metals relative to calcium of at least about 30, or any individual value or sub-range within this range. In some embodiments, the methods provide a selectivity of the one or more target metals relative to magnesium of at least about 30, or any individual value or sub-range within this range. In some embodiments, the adsorption material has a selectivity of the one or more target metals relative to other cations in solution of at least about 5, or any individual value or sub-range within this range. In various embodiments, the metal solution has a concentration of the one or more target metals of less than about 2000 ppm, less than about 500 ppm, less than about 100 ppm, or any individual value or sub-range within these ranges.

[0110] Methods according to various embodiments herein may further include a concentrating step, such as electrodialysis. In some embodiments, the concentrating step comprises reverse osmosis and/or a multistage flash. In at least one embodiment, the method further includes removing the one or more target metals from the purified metal solution. The one or more target metals may be removed by electrodialysis. In some embodiments, the methods further include using a membrane to produce one or more target metal salts.

[0111] According to further embodiments herein are methods of purifying lithium from a lithium containing solution including contacting the lithium containing solution with an adsorption material, wherein the adsorption material binds to one or more impurities to obtain a first processed lithium containing solution; and extracting the first processed lithium containing solution with a second solvent to obtain a purified lithium containing solution. In some embodiments, the purified lithium containing solution contains a higher weight percentage of the lithium than the lithium containing solution, and/or a lower weight percentage of one or more impurities than the lithium containing solution.

[0112] Further described herein are methods of treating feed stocks and/or brines to reduce the total concentration of interfering species (e.g., impurity metals) such as magnesium, calcium, or boron. The methods may result in a reduced amount of these or other impurities in the resultant stream. For example, the methods result in a 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or more, or any individual value or sub-range within these ranges, reduction in the impurities such as impurity cations in the stream. In some embodiments, the reduction may be of calcium ions, magnesium ions, and/or boron in the stream. In various embodiments, the methods may result in a selectivity for the one or more target metals, such as lithium relative to one of the aforementioned impurity metals, of at least 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 35, 40, 45, 50, or greater, or any individual value or sub-range within these ranges. In one or more embodiments, the selectivity for lithium relative to boron may be at least 6, the selectivity for lithium relative to calcium may be at least 30, and/or the selectivity for lithium relative to magnesium may be at least 30.

[0113] In some embodiments, as part of the concentration of the one or more target metals (e.g., lithium), an adsorption operation may be used to remove several impurities to simplify the solvent extraction process. For example, adsorption has the added benefit of having selectivity of lithium, for example, over monovalent and divalent cations. This allows the adsorption process to polish off the divalent cations before being treated by solvent extraction. As a result, there is a reduced requirement for lithium selectivity of the solvent extraction process and for the concentration of monovalent and divalent species in the solvent extraction product solution. This also leads to a higher purity product from the combined adsorbent-solvent extraction process than solvent extraction without adsorbents.

[0114] According to various embodiments, the adsorption process can use compounds (adsorbents) that operate at high temperature (e.g., >90°C, >110°, or even >150° C). Geothermal brines cannot be treated by solvent extraction directly as the temperature of the brine is too high (>50°C). Solvent extraction diluents typically have flash points below about 80°C and few have flash points over about 100°C. The general safety margin for solvent extraction temperature is to have an operating temperature at least about 25°C below the flash point. As the operating temperature increases, the safety margin temperature should also increase. By using adsorption ahead of solvent extraction, the temperature of the aqueous solution reaching solvent extraction may be below about 50°C, or below about 40°C. This is due to the way in which solutions are treated in adsorption. The hot solution could first be passed through the adsorption media. There would be some temperature loss in this step. The media would then be eluted with an aqueous solution that is at a temperature of <50°C.

[0115] Further described herein are methods of using the compositions, systems and apparatus according to embodiments herein. In various embodiments, the described compositions relate to the use of adsorbents that result in the removal of one or more impurities, such as one or more divalent cations. The adsorbents may be an aluminum based compound such as an aluminum hydroxide compound that results in the removal of one or more impurities. This adsorbent may be further immobilized on a solid surface or on a polymer such that the adsorbent may be reused. In various embodiments, the methods may make use of other adsorbents such as other aluminum based adsorbents.

[0116] Hot solutions may be cooled before or after the adsorption step. In at least one embodiment, the hot solution may be cooled by passing through a cooling tower. In another embodiment, the solution may be processed through a heat exchanger to remove the heat and/or the heat may be removed by passing the solution through a thermal storage bed. In some embodiments, heat removal may be accomplished by interchange of the hot solution with the cooled solution downstream of solvent extraction. In some embodiments, the solution may be sent to a cooling pond. Additionally, or alternatively, the solution may be cooled by flashing a portion of it. In various embodiments, methods of cooling the aqueous feed solution include interchange, thermal storage bed, and/or a flash, because the heat energy may be returned to the brine downstream of solvent extraction or used for other purposes.

[0117] While the size of the adsorption plant is built to handle the full aqueous plant flow, the solvent extraction process may be based on the concentrating factor of the adsorption process. Adsorption may concentrate the one or more target metals (e.g., lithium) by using a smaller volume to elute than the feed and/or by taking the eluent and using membrane fdtration (such as reverse osmosis) to remove some of the water from the lithium solution. Because the size of a solvent extraction plant is based on the solution flow, the factor or adsorption concentration is essentially the fraction of solvent extraction plant size.

[0118] In some embodiments, the selectivity of the adsorption process may define the requirements for the selectivity of the solvent extraction reagent. By using a more selective adsorbent, it allows for a less selective solvent extraction reagent. This flexibility enable accommodation of a myriad of brine compositions. By combining these two techniques, it is possible to treat selectivity as a sum of individual process selectivities. An example of this benefit is the removal of boron. Adsorption typically cannot handle boron; however, some solvent extraction operations may reject boron completely.

[0119] In some embodiments, the adsorption system can handle aggressive aqueous systems (temperature as stated above) with the presence of solids or at extremes of pH. This can be difficult for solvent extraction and serves as a pre-treatment of the solution going to solvent extraction. The eluent composition and conditions can be made to be benign for the solvent extraction process. This can include the choice of counterion to the lithium (chloride or sulfate).

[0120] In some embodiments, the combination of adsorption/ solvent extraction can also reduce the amount of water required for the process. For instance, the raffinate from solvent extraction can be used as the wash for the adsorption bed. Also, further reduction in water use can be achieved by blowing out the adsorption bed with a gas, preferably air 421, which removes a large portion of the liquid in the interstices between particles of adsorbent.

[0121] The combination of ad sorption- solvent extraction can be further benefited by the use of bipolar membranes to take the strip solution from solvent extraction and make a final product salt like lithium hydroxide and then recycle the appropriate acid back to the solvent extraction strip step.

EXAMPLES

Example 1

[0122] Elution of an adsorption system occurred using the raffinate of a solvent extraction operation. Raffinate from a solvent extraction process was spiked with sodium chloride to various concentrations to determine the effect on lithium elution from the adsorbent. These elutions were compared to the without any sodium to determine the effect of sodium concentration on the raffinate used in elution. The results are shown in FIG. 6. As shown, an increase in sodium concentration did not have an adverse effect on the elution of lithium. These results demonstrate that the raffinate from a solvent extraction operation may be recycled and reused as the solvent for an adsorption operation in continuous or semi-continuous metal recovery process. A typical evaporation process uses over 100 m³ water per ton of lithium carbonate equivalent (LCE). Compositions, systems and methods according to embodiments herein may reduce water usage to less than about 75 m³, less than about 70 m³, less than about 65 m³, less than about 60 m³, less than about 55 m³, less than about 50 m³, less than about 20 m³, less than about 10 m³, or any individual value or sub-range within these ranges.

[0123] 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.

[0124] 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

CLAIMS What is claimed is:

1. A raffinate composition from a solvent extraction process for use as an eluent to an adsorption process, comprising: a solvent; and at least one metal dissolved in the solvent, wherein the raffinate composition is at a pH suitable for adsorption of a target metal by an adsorbent, and wherein the raffinate composition is at a temperature suitable for adsorption of the target metal by an adsorbent.

2. The raffinate composition of claim 1, wherein the at least one metal is at a concentration of about 1 ppmw to about 1000 ppmw.

3. The raffinate composition of claim 1 or 2, wherein the at least one metal comprises at least one metal cation.

4. The raffinate composition of claim 3, wherein the at least one metal cation is chosen from lithium, calcium, magnesium, potassium, boron, sodium, or combinations thereof.

5. The raffinate composition of any preceding claim, wherein the at least one metal comprises at least one metal anion.

6. The raffinate composition of claim 5, wherein the at least one metal anion is chosen from a halide, a sulfate, a nitrate, or combinations thereof.

7. The raffinate composition of any preceding claim, wherein the pH of the raffinate composition is about 2 to about 11.

8. The raffinate composition of any preceding claim, wherein the temperature of the raffinate composition is about 5°C to about 65°C.

9. The raffinate composition of any preceding claim, wherein the at least one metal is chosen from lithium, sodium, potassium, magnesium, calcium, boron, or combinations thereof.

10. The raffinate composition of any preceding claim, wherein the at least one metal comprises: i) lithium at a concentration of about 0 ppmw to about 800 ppmw, ii) sodium at a concentration of about 0 ppmw to about 20,000 ppmw, iii) potassium at a concentration of about

0 ppmw to about 20,000 ppmw, iv) magnesium at a concentration of about 0 ppmw to about 2,000 ppmw, v) calcium at a concentration of about 0 ppmw to about 4,000 ppmw, vi) boron at a concentration of about 0 ppmw to about 2,000 ppmw, or any combination of i)-vi).

11 . The raffinate composition of any preceding claim, wherein the at least one metal comprises: i) lithium at a maximum concentration of less than about 1,200 ppmw, ii) sodium at a concentration of less than about 30,000 ppmw, iii) potassium at a concentration of less than about 20,000 ppmw, iv) magnesium at a concentration of less than about 4,000 ppmw, v) calcium at a concentration of less than about 2,000 ppmw, vi) boron at a concentration of less than about 2,000 ppmw, or any combination of i)-vi).

12. The raffinate composition of any preceding claim, wherein the solvent comprises ammonium chloride, a conjugate base of ammonium chloride, a conjugate used to neutralize an acid generated during solvent extraction, or combinations of any two or more thereof.

13. The raffinate composition of any preceding claim, wherein the solvent comprises water, an acid, an organic solvent, or a combination of any two or more thereof.

14. The raffinate composition of any preceding claim, further comprising an extractant.

15. The raffinate composition of claim 14, wherein the extractant is selective for trivalent cations, divalent cations, monovalent cations, or combinations thereof.

16. The raffinate composition of claim 15, wherein i) the trivalent cations comprise boron, ii) the divalent cations comprise calcium, magnesium, or combinations thereof, and/or iii) the monovalent cations comprise lithium, sodium, potassium, or combinations thereof.

17. The raffinate composition of any one of claims 14 to 16, wherein the extractant is present at a concentration of about 0.05 M to about the molarity of a neat solution based on the total volume of the raffinate composition.

18. The raffinate composition of any one of claims 14 to 17, wherein the extractant is capable of extracting an alkali metal.

19. The raffinate composition of any one of claims 14 to 18, wherein the extractant is an organic compound comprising one or more anionic functional groups, one or more neutral functional groups, or combinations thereof.

20. The raffinate composition of any one of claims 14 to 19, wherein the extractant is a neutral reagent comprising functional groups having a dipole moment.

21. The raffinate composition of any one of claims 14 to 20, wherein the extractant is a negatively charged extractant that has been activated by removing a proton.

22. A system for recovering a metal from an aqueous solution, comprising: an adsorption system comprising an adsorbent that is selective for a target metal, wherein the adsorption system comprises an inlet for an aqueous solution comprising a plurality of metals at least one of which is the target metal; and a solvent extraction system in fluid communication with the adsorption system, wherein the solvent extraction system comprises an inlet for an eluate from the adsorption system, and an outlet in fluid communication with the inlet of the adsorption system.

23. The system of claim 22, wherein the adsorption system is a fixed bed adsorber, a fluidized- bed adsorber, a pond adsorber, a simulated moving bed adsorber, a fluidized bed adsorber, or a column adsorber.

24. The system of claim 22 or 23, wherein the adsorbent is in the form of sub-units, particles, granules, spheres, microspheres, extrudates, tablets, nanotubes, plate, resin, or a combination of any two or more thereof.

25. The system of any one of claims 22 to 24, wherein the adsorbent comprises aluminum trihydroxide, boron trihydroxide, chromium trihydroxide, molybdenum trihydroxide, lanthanum trihydroxide, rhodium trihydroxide, thulium trihydroxide, zeolite molecular sieve, date pits impregnated with cellulose nanocrystals and ionic liquid, functionalized titanate nanotubes, polymeric porous microspheres with crown ether, granulated chitosan-lithium manganese oxide, manganese-based spinel compounds, modified activated carbon with multiple MnCh nanocomposite ratios, natural and/or synthetic zeolites applying poly(acrylic acid), MnO2-0.4H2O ion sieve, 1 D LiMn2O4 nanorods, nano-lithium ion sieves, intercalated compositions thereof, or combinations of any two or more thereof.

26. The system of any one of claims 22 to 25, wherein the adsorbent is supported on a substrate.

27. The system of any one of claims 22 to 26, wherein the adsorbent is selective for lithium.

28. The system of any one of claims 22 to 27, wherein the solvent extraction system comprises an extractant selective for one or more metals.

29. The system of claim 28, wherein the extractant is selective for calcium, magnesium, or both.

30. The system of claim 28, wherein the extractant is selective for lithium.

31. The system of any one of one of claims 22 to 30, wherein the solvent extraction system comprises a first extractant selective for calcium and magnesium, and a second extractant selective for lithium.

32. The system of any one of claims 22 to 24, wherein the solvent extraction system forms a raffinate depleted of the target metal, and returns the raffinate to the inlet of the adsorption system.

33. The system of any one of claims 22 to 32, wherein the solvent extraction system comprises a separator configured to receive a raffinate depleted of the target metal and remove organic compounds from the raffinate to form a return solution configured to flow through the outlet to the inlet of the adsorption system.

34. The system of claim 33, wherein the separator is a retention pond, a flotation oil water separator, a centrifugal oil water separator, a coagulation system, a chemisorption system, or a combination of any two or more thereof.

35. The system of any one of claims 22 to 34, further comprising an ion removal system for removing one or more impurity metal from a return solution of the solvent extraction system.

36. The system of claim 35, wherein the ion removal system is a reverse osmosis system, an ion exchange system, another solvent extraction system, an electrodialysis system, an evaporation system, a crystallization system, or a combination thereof.

37. A method of recovering a metal from an aqueous solution, comprising: adsorbing a target metal, from the aqueous solution comprising a plurality of metals, onto an adsorbent that is selective for the target metal; eluting the adsorbent to form an aqueous eluate comprising the target metal; contacting the aqueous eluate with an organic phase in a solvent extraction system to extract the target metal into the organic phase and form a raffinate comprising the aqueous eluate depleted of the target metal; and returning the raffinate to the adsorption system.

38. The method of claim 37, wherein the adsorbent is in the form of sub-units, particles, granules, spheres, microspheres, extrudates, tablets, nanotubes, plate, resin, or a combination of any two or more thereof.

39. The method of claim 37 or 38, wherein the adsorbent comprises aluminum trihydroxide, boron trihydroxide, chromium trihydroxide, molybdenum trihydroxide, lanthanum trihydroxide, rhodium trihydroxide, thulium trihydroxide, zeolite molecular sieve, date pits impregnated with cellulose nanocrystals and ionic liquid, functionalized titanate nanotubes, polymeric porous microspheres with crown ether, granulated chitosan-lithium manganese oxide, manganese-based spinel compounds, modified activated carbon with multiple MnCh nanocomposite ratios, natural and/or synthetic zeolites applying poly(acrylic acid), MnCh-O. TbO ion sieve, 1 D LiM C nanorods, nano-lithium ion sieves, intercalated compositions thereof, or combinations of any two or more thereof.

40. The method of any one of claims 37 to 39, wherein the adsorbent is supported on a substrate.

41. The method of any one of claims 37 to 40, wherein the adsorbent is selective for lithium.

42. The method of any one of claims 37 to 41, wherein the solvent extraction system comprises an extractant selective for one or more metals.

43. The method of claim 42, wherein the extractant is selective for calcium, magnesium, or both.

44. The method of claim 42, wherein the extractant is selective for lithium.

45. The method of any one of claims 37 to 44, wherein the solvent extraction system comprises a first extractant selective for calcium and magnesium, and a second extractant selective for lithium.

46. The method of any one of claims 37 to 45, further comprising separating entrained organic compounds from the raffinate before returning the raffinate to the adsorption system.

47. The method of claim 46, wherein separating is in a retention pond, a flotation oil water separator, a centrifugal oil water separator, a coagulation system, a chemisorption system, or a combination of any two or more thereof.

48. The method of any one of claims 37 to 47, further comprising removing one or more impurity metal from the raffinate using an ion removal system.

49. The method of claim 48, wherein the ion removal system is a reverse osmosis system, an ion exchange system, another solvent extraction system, an electrodialysis system, an evaporation system, a crystallization system, or a combination thereof.