Lithium extraction method

Abstract

Provided are a process and apparatus for lithium ion extraction. The process includes passing a lithium-containing brine through a lithium-adsorbent, then passing a desorption media through the lithium-adsorbent at a temperature above 40°C to produce a lithium-enriched eluent. The lithium concentration of the eluent is further increased by passing it through a nanofiltration membrane and a reverse osmosis membrane. Preferably, the eluent is passed through these membranes more than once at a temperature above 40°C. The process is energy-efficient, because it is conducted entirely at temperatures above 40°C. Accordingly, there is no need to decrease the temperature of the lithium-enriched eluent before passing it through the nanofiltration membrane and the reverse osmosis membrane. Moreover, there is no need to increase the temperature of the nanofiltration reverse osmosis permeate before passing it through the lithium-adsorbent as a desorption media, nor is there a need to increase the temperature of the enriched lithium stream before lithium precipitation.

Description

[0001] TITLE OF THE INVENTION

[0002] LITHIUM EXTRACTION METHOD

[0003] CROSS-REFERENCE TO RELATED APPLICATION

[0004] The present application claims priority under 35 U.S.C. § 365(c) to International Application No. PCT / CN23 / 140173, filed on December 20, 2023, which is incorporated herein by reference in its entirety.

[0005] 1. Field of the invention

[0006] Provided herein is a process for selective extraction of lithium from natural or industrial brine reservoirs. More specifically, the process extracts lithium from natural or industrial brine by contacting the brine solution with adsorbent, membrane, ion exchange resin, or the like.

[0007] BACKGROUND OF THE INVENTION

[0008] Several patents, patent applications and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains. The entire disclosure of each of these patents, patent applications and publications are incorporated by reference herein.

[0009] Lithium (Li) is a key component in high-energy-density lithium-ion batteries. Lithium-ion batteries are used in a variety of applications including electric vehicles, computers, and energy storage devices, among others. An increase of the global demand for lithium is anticipated in the foreseeable future. Currently, industrial-scale Li-extraction technology employs chemical treatments followed by evaporation-based processes to recover lithium from different natural and recycled sources, which is time consuming and needs a large-footprint operation.

[0010] Moreover, a large amount of water evaporation is needed to recover Li and most of the natural Li sources are in arid regions with limited clean water availability. To speed up the evaporation process and recover water, engineered processes such as thermal evaporation followed by condensation have been applied, but these are still energy inefficient.

[0011] Various membrane-based processes have been described to recover lithium from natural and recycled sources. U.S. Pat. No. 10,450,633 ('633) describes a membrane-based process to recover Li from acid solutions. A processing-step described in '633 is to pass the acidic lithium solutions through a nanofiltration membrane unit where a fraction of acid and lithium solution permeates through the nanofiltration membrane. U.S. Pat. No. 6,004,464 describes a brine reclamation process from a water-softening resin unit that includes acidifying a chloride- containing brine to a pH range of 0.5-6 and then adding a salt with a monovalent cation and multi-valent anion (for example Na2SO4) to this pH-adjusted brine. CN 112,850,851 describes a Li separation process from a Na2SO4-type salt lake brine that involves adding a chloride (CI-) salt to the brine and pumping it through a nanofiltration system at a pH range of 7.5-11.0 to obtain a superior Li+ / Mg2+separation. CN 108,063,295 describes a process of extracting Li and other heavy metals from a battery source using hydrochloric acid, wherein Li2SO4is added to this acidic feed to react for about 30 minutes under stirring to generate LiCI and CaSO4, which are further separated using a nanofiltration membrane. U.S. Pat. No. 10,604,414 describes a process for recovery of lithium from a geothermal brine using ion exchange and reverse osmosis methods. I ntl. Pat. Appln. Publn. No. WO2023 / 058548 describes a method for recovering monovalent metal ions from a solution containing monovalent metal ions and polyvalent metal ions using a nanofiltration membrane unit and a reverse osmosis membrane unit. U.S. Pat. No. 10,648,061 describes passing a lithium source into and out of a bed of sorbent composed of hydrated alumina intercalated with a lithium halide; washing the bed of sorbent to obtain a lithium eluent of increased lithium concentration; and treating this eluent with nanofiltration and forward osmosis. U.S. Patent Appln. Publn. No. 2022 / 0380223 describes liquid solution concentration methods and related systems involving osmosis units and energy recovery that may include features such as balancing streams, recirculation streams, and / or valving that alone or in combination may afford improved energy efficiency and / or system performance.

[0012] U.S. Patent Appln. Publn. No. 2022 / 00055910 describes a method of isolating lithium as lithium hydroxide or lithium carbonate via sorption / desorption and other purification methods. Various streams, including some lithium-containing streams, are recycled to the sorption / desorption process. In many known lithium extraction processes, including several that are described in the publications cited above, the permeate of a reverse osmosis process is used to elute lithium from an adsorbent. The permeate is typically at a relatively low temperature, such as 35°C or less; however, it is also usually heated to a temperature between 40 and 70°C before eluting the lithium from the adsorbent. The temperature of the eluted stream is then normally reduced to 35°C or less before further purification via reverse osmosis. These temperature adjustments create unnecessary energy waste in the lithium extraction process. For example, Nilsson et al. found that in general the retention of a nanofiltration membrane decreased with increasing temperature. ("The influence of pH, salt and temperature on nanofiltration performance," Journal of Membrane Science 312 (2008) 97-106).

[0013] Clearly, a need for more efficient lithium extraction methods remains, in particular methods that provide a good yield and superior energy efficiency.

[0014] SUMMARY OF THE INVENTION

[0015] Accordingly, provided herein is a process to extract lithium from a feed brine solution or "lithium source." The process includes the combination of separation technologies to extract lithium from feed brine solution with higher efficiency, less energy consumption, and higher returns based on water and energy utilization rates. This process may produce an aqueous lithium salt solution or lithium salt solids with high purity and high extraction yield.

[0016] The brine solution may be a natural brine, a synthetic industrial brine, or a combination thereof, such as continental brine, a geothermal brine, a salt lake brine, an oil field brine, a brine from hard rock lithium mines, a brine extracted from lithium-containing materials, such as recycled lithium-containing equipment, or a combination of two or more thereof.

[0017] The process may include the steps of removing impurities from the brine solution and concentrating the lithium in brine solution by using lithium adsorbent, eluting the lithium from the adsorbent to produce a lithium enriched stream, and then recovering the lithium from the lithium enriched stream. In some instances, the level of enrichment may be such that the lithium enriched stream is considered to be purified. The process may also include the steps of removing divalent impurities from the lithium enriched stream by using a nanofiltration membrane, to form a lithium purified stream and a divalent concentrated stream with less lithium.

[0018] The process may also include the steps of concentrating lithium and dewatering the lithium enriched stream by using a reverse osmosis membrane, to form a more concentrated lithium stream and a permeate stream with a lower concentration of other cations.

[0019] The lithium adsorbent can be designed with a fixed bed, a packed bed, or a continuous ion exchange process, such as for example a continuous countercurrent ion exchange (CCIX) or another suitable design. The lithium adsorbent may comprise any material known to adsorb lithium or lithium ions, for example, a lithium aluminum intercalate prepared from hydrated aluminum, lithium aluminum layered double hydroxide chloride, a layered double hydroxide modified activated alumina, a layered double hydroxide imbedded ion exchange resin or copolymer or molecular sieve or zeolite, layered aluminate polymer blends, a lithium manganese oxide, a titanium oxide, an immobilized crown ether, or a combination of two or more thereof.

[0020] More specifically, the process described herein comprises the steps of:

[0021] (A) providing a lithium source comprising the dissolved lithium ion or a lithium-containing molecule and one or more impurities, such as, without limitation, Na+, Ca2+, Mg2+, dissolved silicates, or boron;

[0022] (B) passing the lithium source through a bed of adsorbent at the ambient temperature of the lithium source, for example an adsorbent comprising an aluminum / lithium element or manganese, or titanium, to extract lithium ion from the lithium source onto the adsorbent;

[0023] (C) rinsing the adsorbent bed with desorption media at temperature above 40°C, wherein the desorption media comprises pure water or a dilute aqueous salt solution, for example a dilute lithium halide solution, to obtain a lithium rich eluent;

[0024] (D) adjusting the pH of the lithium rich eluent to below 6.0;

[0025] (E) subjecting the lithium rich eluent from step (D) to a pressurized semi permeable membrane system at a temperature above 40°C, wherein the membrane system includes a nanofiltration membrane and a reverse osmosis membrane, to selectively remove divalent ions and to increase the lithium concentration;

[0026] (F) optionally passing the solute through at least one nanofiltration membrane that rejects divalent ions, for example the nanofiltration membrane of step (E), wherein a majority of the lithium ions and water of the lithium rich eluent passes through one nanofiltration membrane at least two times or through two or more nanofiltration membranes;

[0027] (G) optionally passing the solute through at least one reverse osmosis membrane that rejects soluble ions and neutral organic molecules, for example the reverse osmosis membrane of step (E), wherein a majority of the water molecule passes through one reverse osmosis membrane at least one time or through one or more reverse osmosis membranes; and

[0028] (H) using the permeate stream generated by the reverse osmosis membrane in the semipermeable membrane system at a temperature above 40°C as at least a portion of the desorption media for lithium adsorbent bed desorption in step (D).

[0029] The above process is generally used for the primary lithium extraction from the brine solution containing lithium ions in a concentration of at least 10 ppm. The process may further comprise one or more of the following optional steps (OS):

[0030] (OS1) After the step (E) the purified lithium containing stream is treated by ion exchange resin bed at temperature above 40°C, which is preferably a chelating resin, to remove the residual divalent cations, for example Ca2+or Mg2+;

[0031] (OS2) After the step (E) the purified lithium containing stream is treated by ion exchange resin bed at temperature above 40°C, which preferably is a chelating resin, to selectively remove boron species, for example boric acid or borates;

[0032] (OS3) After the step (E) the purified lithium containing stream undergoes a concentration step at temperature above 40°C to increase the lithium ion concentration in solution, for example using one or more of a thermal multiple effect evaporator, a mechanical vapor compressor, or electrodialysis; (0S4) After the step (E) the purified lithium containing stream is precipitated by adding carbonate or another anion of a lower-solubility lithium salt at temperature above 40°C to convert the dissolved lithium ion into solid form, for example by dosing with sodium carbonate to obtain lithium carbonate precipitates; and

[0033] (OS5) After the step (E) the purified lithium containing stream is treated by an electrodialysis method to produce lithium hydroxide. Then, the solid lithium hydroxide can be obtained, for example by crystallization or by a combination of techniques such as concentration and crystallization.

[0034] The first optional step (OS 1) may be conducted to remove the divalent impurities from the lithium rich stream of the outlet of semipermeable membrane system. Before OS1, the amount of divalent impurities in the lithium rich stream of the outlet of semipermeable membrane system may be in the range of 10 ppm to 5000 ppm. After the OS1 step, the amount of divalent impurities is reduced to below 1 ppm, and preferably below 0.1 ppm or 0.02ppm.

[0035] The second optional step (OS2) may be conducted to remove boron impurity from the lithium rich stream of the outlet of semipermeable membrane system. Before OS2, the amount of boron in the lithium rich stream of the outlet of semipermeable membrane system may be in the range of 10 ppm to 5000 ppm, measured as elemental boron by inductively coupled plasma (ICP). After the OS2 step, the amount of boron is reduced to below 10 ppm, and preferably below 5 ppm or below 1 ppm, again measured as elemental boron by ICP.

[0036] The third optional step (OS3) may be conducted to dewater the lithium rich solution in order to increase the lithium concentration. The lithium concentration increase is helpful if the final product speculation needs such high concentration solution, or if the fourth optional step (OS4) chemical precipitation method is used to obtain solid form lithium product. The semi permeable membrane can increase the lithium concentration from 100 or 5000 to 10000 or 15000 ppm (wt lithium). OS3 step can further concentrate to 20000 ppm, 30000 ppm, or 35000 ppm (wt lithium).

[0037] The fourth optional step (OS4) may be conducted to convert the dissolved lithium ion into a solid salt, for example solid lithium carbonate, by dosing with a carbonate salt such as sodium carbonate, so that lithium carbonate will be precipitated. The fifth optional step (OS5) may be conducted to produce lithium hydroxide. Lithium hydroxide (LiOH) is a major lithium salt for the production of nickel-rich cathode materials. Electrodialysis is a promising method to produce lithium hydroxide from lithium rich solutions, which has been well reported. See, for example, Jiang et al., Production of Lithium Hydroxide from Lake Brines through Electro-Electrodialysis with Bipolar Membranes (EEDBM), Ind. Eng. Chem. Res. 2014, 53, 14, 6103-6112; linked at https: / / doi.org / 10.1021 / ie404334s). Solid lithium hydroxide can be obtained from the lithium hydroxide solution that is produced by electrodialysis, for example by crystallization.

[0038] The advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. For a better understanding of the invention, its advantages, and the objects obtained by its use, however, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described one or more preferred embodiments of the invention.

[0039] BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will now be described with reference to the accompanying drawings, in which:

[0041] FIG. 1 is a schematic diagram of a first apparatus that is suitable to practice the methods of the invention.

[0042] FIGS. 2A, 2B, and 2C are schematic diagrams of further apparatuses that are suitable to practice the methods of the invention.

[0043] DETAILED DESCRIPTION OF THE INVENTION

[0044] Lithium adsorbent

[0045] Any lithium adsorbent known in the art may be suitable for use in the processes described herein. Some suitable adsorbents and methods of synthesizing the adsorbents are described in U.S. Pat. Nos. 11,371,118 and 4,348,296, for example. These patents describe a method of making an aluminum / lithium complex based on an organic or inorganic matrix. Alternatively, a suitable aluminum / lithium complex may be made from an aluminum source such as Gibbsite, bayerite, nordstrandite, bauxite, or other aluminum-containing minerals.

[0046] In more preferred embodiments, the lithium adsorbent media comprises a particulate composition, which in turn comprises a collection of resin beads and LiX-2AI(OH)3-nH2O, wherein n is 0 to 10; wherein X is a halogen; and wherein the resin beads are characterized by two or more of the following properties: the resin beads contain polymer having 0.5 to 3 equivalents of amine pendant groups per liter of the particulate composition; wherein the resin beads have average pore diameter of 5 to 100 nm; wherein the collection of resin beads has harmonic mean particle diameter of 200 to 1000 micrometers; wherein the collection of resin beads has surface area of 20 to 150 m2 / g; and wherein aluminum is present in an amount of 14.5% percent or higher, by weight of aluminum atoms based on the total weight of the particulate composition.

[0047] In still more preferred embodiments, the resin beads possess all of these properties.

[0048] Lithium adsorption and desorption

[0049] The lithium adsorption is conducted by passing the lithium containing brine source through the lithium adsorbent bed, which comprises the lithium adsorbent media. The lithium adsorption may be conducted at a temperature below 40°C, for example 35°C or below, 30°C or below, 27°C or below, 25°C or below, or at ambient temperatures. The lithium ion is adsorbed onto the solid based adsorbent, and the aqueous liquid leaves from the adsorbent bed with reduced lithium ion concentration. The lithium adsorbent can adsorb the lithium ion from lithium brine source with any lithium concentration, and the preferred lithium concentration in the brine source is above 10 ppm. A higher lithium concentration in the brine solution will result in a higher lithium ion load in the adsorbent.

[0050] The lithium adsorbent may be loaded in a fixed bed or a packed bed, or in a continuous ion exchange apparatus, such as for example a continuous countercurrent ion exchange (CCIX) apparatus, or continuous adsorption / desorption, or another suitable design. When the lithium ions in the lithium rich effluent break through the adsorbent bed, the adsorption process is stopped and the desorption step is prepared. Lithium ions may be detected in the fluid passing through the adsorption bed by conventional means, such as ICP, for example. Alternatively, the lithium concentration of the lithium source and the lithium ion capacity of the adsorbent bed may be determined. With this information, the adsorption may be discontinued when a volume of the lithium source that contains the lithium ion capacity of the adsorbent bed has been flowed through the bed. If the flow rate of the lithium source is also known, the adsorption may be discontinued after a fixed adsorption time.

[0051] The lithium desorption step is conducted by passing the desorption media into the adsorbent bed after the lithium adsorption step. The temperature of desorption media is between 40 to 100°C, and preferably at 60 to 80°C. The higher the temperature of the desorption media, the higher the lithium desorption efficiency, and the higher the lithium concentration in the adsorption effluent. Significantly, however, there is a temperature above which no benefit to desorption is obtained. At these excessively high temperatures, heat is dissipated to the atmosphere. Therefore, the maximum desorption temperature is set according to the engineering environment and heat loss rate. Moreover, the higher the desorption temperature, the higher the temperature for the fluid entering the semipermeable membrane system. As a result, at these higher temperatures the entire lithium extraction plant has a higher temperature gradient between the processing fluid and the ambient environment, and thus the heat loss rate is higher. Advantageously, however, in the processes described herein, which are carried out at temperatures between 40 to 100°C, and preferably at 60 to 80°C, there is no need to waste energy by raising the temperature of the desorption media prior to eluting the lithium from the adsorbent bed, or by reducing the temperature of the lithium enriched eluent prior to the reverse osmosis / nanofiltration processes. There is also no need to waste energy by raising the temperature of the lithium concentrated stream after semi permeable system and before lithium precipitation steps.

[0052] The desorption media can be deionized water or a dilute aqueous salt solution, for example a dilute lithium solution. A small quantity of lithium ion in the desorption media may be beneficial for higher desorption efficiency. The lithium ion concentration in desorption media may be below 1000 ppm, and preferably between 50 and 500 ppm. It is noteworthy that the whole of the system described herein, including the desorption of lithium from the adsorbent bed and the semi permeable membrane system, is operating at high temperature, that is, at or above 40°C. The reverse osmosis membrane has higher ion permeability at high temperature than room temperature, however, and therefore the reverse osmosis permeate stream from the semipermeable membrane system is expected to contain a small quantity of lithium ion. In fact, there is no need for the reverse osmosis permeate to be very purified or deionized water. The amount of lithium ion in the reverse osmosis permeate may be below 1000 ppm, and preferably between 50 and 500 ppm, for the permeate to perform effectively as the desorption media.

[0053] The lithium enriched eluent after adsorbent desorption is collected for the next step processing. Preferably, its lithium concentration after desorption is between 100 or 200 to 10000 ppm, and more preferably between 200 or 500 ppm to 2000 or 3000 ppm.

[0054] Lithium separation and concentration

[0055] The high quality final lithium product is generally used as a raw material for lithium battery making, or as a raw material for another industrial use such as glass, ceramics, lubricants or organic synthetic materials, for example. Such high quality lithium product may require downstream processing steps after elution from the lithium adsorbent to remove any residual impurities and to further increase the lithium concentration. The impurities present in the lithium-rich eluent before downstream processing may include one or more of Ca2+, Mg2+, dissolved silicates, and boron, and the like. The concentration of divalent cationic impurities after downstream processing should be as low as possible, preferably less than 1 ppm, or more preferably, less than 0.1 or 0.02 ppm. The concentration of boron after downstream processing should be less than 10 ppm, or preferably, less than 5 ppm. The lithium ion concentration after downstream processing should be increased from hundreds or thousands of ppm of lithium to higher than 10000 ppm (wt lithium), or preferably, higher than 20000 or 25000 ppm (wt lithium).

[0056] The process described herein for the lithium separation and concentration of the lithium rich effluent is accomplished by an integrated process that combines but is not limited to nanofiltration and reverse osmosis, and optionally hardness / boron removal ion exchange resin, thermal evaporator, and lithium precipitation, etc. All the steps described above are operated at a temperature or temperatures above 40°C. The purpose of downstream processing is to obtain high purity lithium product, while at the same time minimizing the processing operational cost, such as, for example, raw material cost, energy consumption, and production yield loss. Semi permeable membrane

[0057] As used herein, the term "semi permeable membrane" includes reverse osmosis membrane and nanofiltration membrane. While various membrane configurations may be used, (e.g. hollow fiber, tubular, plate and frame), spiral wound modules, referred to interchangeably herein as "spiral-wound elements," are preferred. Reverse osmosis membranes are relatively impermeable to virtually all dissolved salts and typically reject more than about 95% of salts having monovalent ions such as sodium chloride. Reverse osmosis membranes also typically reject more than about 95% of inorganic molecules as well as organic molecules with molecular weights greater than approximately 100 Daltons. Nanofiltration membranes are more permeable than reverse osmosis membranes and typically reject less than about 95% of salts having monovalent ions while rejecting more than about 35% (and often more than 50%, sometimes even more than 90%) of salts having divalent ions— depending upon the species of divalent ion, feed stream conditions such as temperature, pH, etc. These percentages are weight percentages, based on the total weight of dissolved salts in the liquid that is fed to the semi permeable membrane. Nanofiltration membranes also typically reject particles in the nanometer range as well as organic molecules having molecular weights greater than approximately 200 to 500 Daltons.

[0058] Spiral wound module construction has been described in detail elsewhere (see, for example, U.S. Pat. Nos. 6,881,336; 8,142,588; and 8,496,825). Spiral wound membrane modules may be formed by winding one or more membrane envelopes and optional feed channel spacer sheet(s) ("feed spacers") about a permeate collection tube. Each membrane envelope preferably comprises two substantially rectangular membrane sheets surrounding a permeate channel spacer sheet ("permeate spacer"). This sandwich-type structure is secured together, e.g. by sealant, along three edges while the fourth edge abuts the permeate collection tube. The permeate spacer is in fluid contact with openings passing through the permeate collection tube. An outer housing of the element may be constructed from a variety of materials including stainless steel, tape, PVC, fiber glass and epoxy material. Additional details regarding various components and construction of spiral wound elements are provided in the literature; see for example: U.S. Pat. No. 5,538,642, which describes a technique for attaching a permeate spacer to a permeate collection tube; U.S. Pat. No. 7,951,295, which describes trimming operations and the use of a UV adhesive for forming an insertion point seal; and U.S. Pat. No. 7,875,177, which describes an applicable leaf packet.

[0059] The membrane sheet is not particularly limited and a wide variety of materials may be used, e.g. cellulose acetate materials, polysulfone, polyether sulfone, polyamides, polyvinylidene fluoride, etc. A preferred membrane sheet is a composite structure having a discriminating layer formed by interfacial polymerization. A typical composite hyperfiltration membrane includes a backing layer (back side) of a nonwoven backing web (e.g. a non-woven fabric such as polyester fiber fabric available from Awa Paper Company of Tokushima, Japan), a middle layer comprising a porous support having a typical thickness of about 25-125 pm, and a top discriminating layer (front side) comprising a thin film polyamide layer having a thickness typically less than about 1 micron, e.g. from 0.01 micron to 1 micron but more commonly from about 0.01 to 0.1 pm. The backing layer is not particularly limited but preferably comprises a non-woven fabric or fibrous web mat including fibers which may optionally be oriented. Alternatively, a woven fabric such as sail cloth may be used. Representative examples are described in U.S. Pat.

[0060] Nos. 4,214,994; 4,795,559; 5,435,957; 5,919,026; 6,156,680; U.S. 2008 / 0295951 and U.S. Pat. No. 7,048,855. The porous support is typically a polymeric material having pore sizes which are of sufficient size to permit essentially unrestricted passage of permeate but not large enough so as to interfere with the bridging over of a thin film polyamide layer formed thereon. For example, the pore size of the support preferably ranges from about 0.001 to 0.5 pm. Nonlimiting examples of porous supports include those made of: polysulfone, polyether sulfone, polyimide, polyamide, polyetherimide, polyacrylonitrile, poly(methyl methacrylate), polyethylene, polypropylene, and various halogenated polymers such as polyvinylidene fluoride. The discriminating layer is preferably formed by an interfacial polycondensation reaction between a polyfunctional amine monomer and a polyfunctional acyl halide monomer upon the surface of the microporous polymer layer as described in U.S. Pat. Nos. 4,277,344 and 6,878,278, for example.

[0061] While modules are available in a variety of sizes, one common industrial reverse osmosis module is available with a standard 8 inch (20.3 cm) diameter and 40 inch (101.6 cm) length. For a typical 8 inch diameter module, 20 to 30 individual membrane envelopes are wound around the permeate collection tube (i.e. for permeate collection tubes having an outer diameter of from about 1.5 to 1.9 inches (3.8 cm-4.8 cm)). One or more modules are arranged within a pressure vessel. The pressure vessels used in the present invention are not particularly limited but preferably include a solid structure capable of withstanding pressures associated with operating conditions. The vessel structure preferably includes a chamber having an inner periphery corresponding to that of the outer periphery of the spiral wound modules to be housed therein. The length of the chamber preferably corresponds to the combined length of the elements to be sequentially (axially) loaded, e.g. 1 to 8 elements, see U.S. 2007 / 0272628. The pressure vessel may also include one or more end plates that seal the chamber once loaded with modules. The vessel further includes at least one fluid inlet and outlet preferably located at opposite ends of the chamber. The orientation of the pressure vessel is not particularly limited, e.g. both horizontal and vertical orientations may be used. Examples of applicable pressure vessels, module arrangements and loading are described in: U.S. Pat. Nos. 6,074,595; 6,165,303; 6,299,772; and U.S. 2008 / 0308504. Manufacturers of pressure vessels include Pentair of Minneapolis, Minn., Bekaert of Vista, Calif., and ROPV of Harbin, China.

[0062] An individual pressure vessel or a group of vessels working together, each equipped with one or more modules, is commonly referred to as a "unit", a "skid", a "train", or a "pass." The vessel(s) within the pass may be arranged in one or more stages, wherein each stage contains one or more vessels operating in parallel with respect to a feed fluid. Multiple stages are arranged in series, whereby the concentrate fluid from an upstream stage is used as feed fluid for the downstream stage, while the permeate from each stage may be collected without further reprocessing within the pass. Multi-pass hyperfiltration systems are constructed by interconnecting individual passes along a fluid path way as described in: U.S. Pat.

[0063] Nos. 4,156,645; 6,187,200; and 7,144,511, for example.

[0064] The semi permeable membrane system, including nanofiltration and reverse osmosis membrane units, could be designed by connecting these units in series or in parallel. It means that the concentrate stream and permeate stream of each reverse osmosis or nanofiltration train could be connected with another reverse osmosis or nanofiltration train, so as to purify the lithium stream or concentrate the lithium stream. Suitable train connection schemes include but are not limited to the options depicted in Figures 1 and 2. Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to Figure 1, there is illustrated a system that is suitable for the practice of the processes described herein. The components depicted in the Figures are listed below:

[0065] (A) water or another desorption media from pure water tank (PW) is passed through a line (TCO) to a heat exchanger (HE) and then via the desorbent stream (DS) through the lithium adsorbent bed (LA) to produce the lithium rich eluent (TCI), which is connected with the feed side of a nanofiltration membrane (NF1), to separate the divalent and monovalent ions, producing a concentrate stream comprising concentrated divalent ions and reduced monovalent ions (TC3) and a permeate stream comprising reduced divalent ion and monovalent ion with higher purity (TC7); the adsorbent bed (LA) is further equipped with a line (LSI) for bringing a lithium source such as a brine into the adsorbent bed (LA) and a line (LS2) for returning brine to the lithium source, for example brine that has exited the adsorbent bed (LA) after the lithium ion in brine has been adsorbed by adsorbent bed (LA);

[0066] (B) the lithium rich eluent (TCI) is also connected with the feed inlet (TC2) of a reverse osmosis membrane (RO1), to reject ions, producing a second concentrate stream comprising concentrated ions (TC11) and a second permeate stream comprising a reduced ion concentration (TC15) ;

[0067] (C) the concentrate stream (TC3) of the first nanofiltration membrane (NF1) is connected to a second nanofiltration membrane (NF2) via line (TC4) to further separate divalent and monovalent ion (via permeate line TC18 and retentate line TC19); or a second reverse osmosis membrane (RO2) via line (TC5) to further increase ion concentration (via permeate line (TC20) and retentate line (TC21)); or via line (TC6) to a waste stream outlet for wastewater disposal or discharge; in addition, the permeate stream (TC7) of the first nanofiltration membrane (NF1) is connected via line (TC8) to a third nanofiltration membrane (NF3) to further separate divalent and monovalent ion via permeate line (TC22) and retentate line (TC23); or via line (TC9) to a third reverse osmosis membrane (RO3) to further increase ion concentration (via permeate line (TC24) and retentate line (TC25)); alternatively, the lithium rich stream may be transported to the next step in lithium processing via line (TC10); (D) the concentrate stream (TC11) of the first reverse osmosis membrane (RO1) is connected to a fourth nanofiltration membrane (NF4) via line (TC12) to further separate divalent and monovalent ion (via permeate line (TC26) and retentate line (TC27)); or to a fourth reverse osmosis membrane (RO4) via line (TC13) to further increase ion concentration (via permeate line (TC28) and retentate line (TC29)); alternatively, the lithium rich stream may be transported to the next step in lithium processing via line (TC14). The permeate stream (TC15) of the first reverse osmosis membrane (RO1) is connected via a line (TC16) to a fifth reverse osmosis membrane (ROS) to further deionize the water stream (via permeate line (TC30) and retentate line (TC31)), or to the ion removed water stream for desorption preparation (TC17);

[0068] (E) one or more of the concentrate streams (TC19, or TC23, or TC27) of the second, third, or fourth nanofiltration membrane (NF2, NF3, NF4) is connected to a fifth nanofiltration membrane (not shown) to further separate divalent and monovalent ion; or to a sixth reverse osmosis membrane (not shown) to further increase ion concentration; or to a waste stream outlet (via line TC6, TC10, or TC14) for wastewater disposal or discharge; alternatively, one or more of the concentrate streams (TC19, or TC23, or TC27) may be fully recycled or partially recycled back to the upper stream membrane (via one or more of FT1, FT10, FT2, FT3, FT4, FT5, FT6, FT7, and FT8). One or more of the permeate streams (TC18, or TC22, or TC26) of the second, third, or fourth nanofiltration membrane (NF2, NF3, NF4) is connected to a seventh reverse osmosis membrane ((RO7), see Fig. 2A) to further increase ion concentration; or to the lithium rich stream for next step lithium processing (connection not pictured); alternatively, one or more of the permeate streams may be fully recycled or partially recycled back to the feed line of semi permeable membrane (via one or more of FT1, FT1O, FT2, FT3, FT4, FT5, FT6, FT7, and FT8);

[0069] (F) the concentrate stream (TC21, TC25, TC29, or TC31) of the second , third, fourth, or fifth reverse osmosis membrane (RO2, RO3, RO4, RO5) is connected to a sixth nanofiltration membrane (see Fig. 2B) to further separate divalent and monovalent ion; or to an eighth reverse osmosis membrane (see Fig. 2B) to further increase ion concentration; or to the lithium rich stream for next step lithium processing. The permeate stream (TC20, or TC24, or TC28, or TC30) of the second or third reverse osmosis membrane is connected to a ninth reverse osmosis membrane (not shown) to further reduce ion concentration; or other polishing treatment, or preparation step as desorption media; alternatively, one or more of the permeate streams may be fully recycled or partially recycled back to the upper stream membrane (via one or more of FT1, FT1O, FT2, FT3, FT4, FT5, FT6, FT7, and FT8). Deionized water is especially helpful to enhance the monovalent ion / multi-valent ion separation efficiency of nanofiltration membrane, which is reported elsewhere (Journal of Membrane Science, 2024, 711, 123173; Separation and Purification Technology, 2020, 247, 116965);

[0070] (G) the sequence from (A) to (F) in its entirety or in one or more subsets could repeat with multiple rounds, for example by routing one or more of the lines (TC18, TC19, TC20, TC21, TC22, TC23, TC24, TC25, TC26, TC27, TC28, TC29, TC30, TC31) to the feed line of downstream membrane. For example, routing TC18 to RO7 in Fig 2 (A), routing TC20 to RO8 and routing TC21 to NF6 in Fig2 (B), routing TC27 to NF7 in Fig 3(C), so as to increase the divalent / monovalent ion separation efficiency, lithium recovery, and concentrate to higher targeted ion (e.g., lithium) concentration;

[0071] (H) in addition, the stream(s) that enter into the nanofiltration or reverse osmosis membrane(s) (e.g. mentioned but not limited to TCI, TC2, TC4, TC5, TC8, TC9, TC12, TC13, TC16) could be mixed with another stream from the nanofiltration or reverse osmosis membrane outlets, wherein the outlet is a concentrate outlet or a permeate outlet. In this connection, dashed arrows FT1, FT2, FT3, FT4, FT5, FT6, FT7, FT8, FT9, and FT10 illustrate points at which fluid from another train or pass may enter the system depicted in Fig. 1.

[0072] Referring now to Fig. 2A, another system that is suitable for the practice of the processes described herein is depicted. In this system, the method includes the feature that the permeate of the RO and NF membranes is transported through line (TC35)and added to the tank (PW) to be recycled into desorption media that passes through the lithium adsorption bed (LA).

[0073] Alternatively, line (TC35) may lead to a next reverse osmosis pass or to another polishing step (not shown), either before or as an alternative to depositing the permeate in the tank (PW). In addition, the semi permeable membrane system includes two nanofiltration units (NF1, NF2) in series, and these two NF units are connected in series with two reverse osmosis units (RO7, RO7A) which in turn are connected in series. Stated alternatively, the four hyperfiltration membranes depicted in Fig. 2A are connected in series. Further depicted is a dashed arrow for line (TC19), showing that the retentate of nanofiltration units (NF2) may optionally be combined with lithium rich eluent (TCI) for reprocessing through the nanofiltration units (NF1 and NF2). Similarly, line (TC34) shows that the retentate of reverse osmosis unit (RO7A) may be combined with the line (TC18) of permeate from the nanofiltration unit (NF2) for reprocessing through the reverse osmosis units (RO7 and RO7A). Finally, the retentate stream (TC7) of the first nanofiltration membrane (NF1) may be discharged as a depleted brine or processed through another nanofiltration membrane (not shown). Likewise, the retentate stream (TC33) produced by reverse osmosis membrane (RO7) may be connected with another nanofiltration membrane (not shown) to further separate divalent and monovalent ion; or to another reverse osmosis membrane (not shown) to further increase ion concentration; or to the lithium rich stream for next step lithium processing.

[0074] Referring now to Fig. 2B, yet another system that is suitable for the practice of the processes described herein is depicted. In this system, the method includes the feature that the permeate of the RO and NF membranes is transported through line (TC38) and added to the tank (PW) to be recycled into desorption media that passes through the lithium adsorption bed (LA).

[0075] Alternatively, line (TC38) may lead to a next reverse osmosis pass or to another polishing step (not shown), either before or as an alternative to depositing the permeate in the tank (PW). The lithium enriched eluent passes through line (TCI) to nanofiltration unit (NF1). The retentate stream (TC7) of the first nanofiltration membrane (NF1) may be discharged as a depleted brine or processed through another nanofiltration membrane, and the permeate line (TC3) is also the inlet line (TC5) for reverse osmosis unit (RO2). Retentate line (TC21) of reverse osmosis unit (RO2) is also the inlet of nanofiltration unit (NF6), and permeate line (TC20) of reverse osmosis unit (RO2) is the inlet line of reverse osmosis unit (RO8). Permeate line (TC38) is recycled to tank (PW), and the retentate line (TC37) of reverse osmosis unit (RO8) is combined with the inlet feed line (TC5) of reverse osmosis unit (RO2). A portion of retentate line (TC39) of nanofiltration unit (NF6) may be processed through another nanofiltration membrane (not shown); another portion, indicated by dashed arrows (TC39) may be combined with the fluids in one or more of lines (TCI), (TC3), or (TC5). The permeate of nanofiltration unit (NF6) is connected through line (TC40); It may be connected with another nanofiltration membrane (not shown) to further separate divalent and monovalent ion; or to another reverse osmosis membrane (not shown) to further increase ion concentration; or to the lithium rich stream for next step lithium processing.

[0076] Referring now to Fig. 2C, yet another system that is suitable for the practice of the processes described herein is depicted. In this system, the method includes the feature that the permeate of the reverse osmosis membrane (RO5) is transported through line (TC30) and added to the tank (PW) to be recycled into desorption media that passes through the lithium adsorption bed (LA). Alternatively, permeate line (TC30) may lead to a next reverse osmosis pass or to another polishing step (not shown), either before or as an alternative to depositing the permeate in the tank (PW). In Fig. 2C, the lithium rich eluent is fed through line (TC2) to a first reverse osmosis unit (RO1). The permeate of reverse osmosis unit (RO1) is fed through lines (TC15, TC16) to another reverse osmosis unit (RO5), and the retentate is fed through lines (TC11, TC12) to a nanofiltration unit (NF4). The retentate of nanofiltration unit (NF4) may be passed through line (TC26) to be discharged as a depleted brine or processed through another nanofiltration membrane (not shown). The permeate of nanofiltration unit (NF4) may be passed through line (TC27) to become the inlet feed of nanofiltration unit (NF7). The retentate of nanofiltration unit (NF7) is routed through line (TC41) to combine with the inlet feed of nanofiltration unit (NF4) in lines (TC11, TC12). The lithium-rich permeate of nanofiltration unit (NF7) is discharged through line (TC42); it may be connected with another nanofiltration membrane (not shown) to further separate divalent and monovalent ion; or to another reverse osmosis membrane (not shown) to further increase ion concentration; or to the lithium rich stream for next step lithium processing. Finally, the retentate of reverse osmosis unit (RO5) is routed through line (TC31) to combine with the inlet feed of reverse osmosis unit (RO1) in line (TC2).

[0077] The terms "feed side" and "feed inlet" are synonymous and used interchangeably herein. The terms "permeate side" and "permeate outlet" are synonymous and used interchangeably herein. The terms "concentrate side" and "concentrate outlet" are synonymous and used interchangeably herein.

[0078] Significantly, in the processes described herein, a majority of the lithium ions, water, or both lithium ions and water of the lithium rich eluent passes through one nanofiltration membrane at least twice or through two or more nanofiltration membranes to produce a permeate that is enriched in lithium and a brine that is depleted in lithium and depleted in divalent ions.

[0079] Also significantly, each of the nanofiltration and reverse osmosis units has a feed inlet, a concentrate outlet, and a permeate outlet. Preferably, the concentrate outlet volumetric flow is less than 70%, 60%, 50%, 40% or less than 30% of feed inlet volumetric flow, and the permeate outlet volumetric flow is more than 30%, 40%, 50%, 60%, or more than 70% of feed inlet volumetric flow.

[0080] In a preferred embodiment, the nanofiltration membrane includes one or more piperazine- based membranes. Suitable membranes include several FilmTec™ products, for example Fortilife™ XC-N, and FilmTec™ LiNE-XD or LiNE-XD HP elements. In the same preferred embodiment, or in other preferred embodiments, the reverse osmosis membrane includes one or more membranes based on aromatic polyamides, such as MPD (meta-phenylene diamine). Suitable membranes include several FilmTec™ products, for example FilmTec™ BW30-400, FilmTec™ BW30XFR-400 / 34i, SW30XHR-400, SW30HRLE-370 / 34i, Fortilife™ CR100, Fortilife™ XC70, or Seamaxx™ elements. These nanofiltration and reverse osmosis elements are available commercially through DuPont de Nemours, Inc. of Wilmington, DE (hereinafter "DuPont"). The nanofiltration or reverse osmosis elements may be serially connected or connected in parallel in a common pressure vessel, with the proviso that at least two reverse osmosis elements or at least two nanofiltration elements are connected in series, or with the alternate proviso that the lithium rich eluent passes through one nanofiltration membrane at least twice. Stated alternatively, the lithium ions preferably pass through at least two nanofiltration membranes, or through a single nanofiltration membrane at least twice. In addition, the water preferably passes through at least one reverse osmosis membrane, or through a reverse osmosis membrane at least once. The pressure vessels may be connected using standard pipes, valves, junctions, etc.

[0081] The lithium enriched concentrate stream or brine leaving the semi permeate membrane system contains lower levels of impurities and a higher concentration of lithium ion. Its temperature is above 40°C, preferably between 60 and 80°C. The lithium ion concentration of the lithium- enriched concentrate stream may be higher than 5000 ppm (wt lithium), or preferably, higher than 10000 ppm (wt lithium).

[0082] The permeate stream leaving the semi permeable membrane system is the stream that passed most recently through a reverse osmosis membrane, and its temperature is above 40°C, or preferably between 60 and 80°C. This stream comprises mostly water molecules, and more than 80% of the ions including Ca2+, Mg2+, Na+, Li+, SO42', and Cl' are removed, based on the concentrations of these ions in the lithium-rich eluent. For the divalent ions Ca2+, Mg2+, and SO42', the ion removal rate is preferably more than 85%, more preferably more than 90%, also based on the concentrations of these ions in the lithium-rich eluent.

[0083] For the Li+ion, it is preferred to leave dilute lithium ion in the reverse osmosis permeate water for facilitating the lithium adsorbent desorption process, when this permeate is used as at least a portion of the desorption media. The lithium ion concentration in desorption media is below 1000 ppm, and preferably between 50 and 500 ppm. In some preferred methods, the reverse osmosis permeate has a lithium ion concentration below 50 ppm. It may then be dosed with concentrated dissolved lithium solution in an appropriate amount such that a suitable lithium concentration is achieved for improving or maximizing lithium adsorbent desorption efficiency. In addition, the reverse osmosis permeate water, after deionization, may be reused for other purposes including without limitation boiler feed, raw material dissolving, and various process aids such as liquids for flushing or cleaning.

[0084] It is well-known that the feed solution pH can impact the semi permeable membrane system performance. Accordingly, it may be necessary to adjust the pH of the lithium rich effluent before processing it through the reverse osmosis / nanofiltration membranes. The pH adjustment could be done by dosing the effluent with acid or caustic in liquid or solid form before it enters into the semi permeable membrane train, for example via lines TCI and TC2, as depicted in Fig. 1. For a nanofiltration membrane that aims to separate monovalent and divalent cations in the methods described herein, the operation pH is ranged between pH 1.0 and 6.0, or preferably between 2.0 and 5.0, or more preferably between 2.5 and 4.0. Low pH is beneficial to increase the divalent cation rejection and maintain the monovalent cation passage. For the reverse osmosis system, the operation pH is ranged between pH 1.0 and 14.0 for the removal of ionic species in general. Preferably, if the reverse osmosis membrane is intended to reject boron species, the pH will be adjusted to above 8.0, or more preferably to above 9.5. Preferably, if the reverse osmosis is aimed to reject other ions such as Ca2+, Mg2+, Na+, Li+, dissolved silicates, etc., and to allow boron to pass through the membrane, the pH will be adjusted to less than 8.0, preferably less than 5.0.

[0085] Residual hardness removal

[0086] The residual hardness in the lithium enriched concentrate stream or brine after processing through the semi permeable membrane system, including Ca2+or Mg2+, may be removed by a chelating ion exchange resin at temperature above 40°C, or preferably between 60 and 80°C. The lithium containing stream passes through a resin bed that is filled with chelating ion exchange resin, in a fixed bed or packed bed, in a continuous ion exchange process, such as for example a continuous countercurrent ion exchange (CCIX) apparatus, or in another suitable design. In a preferred embodiment, the chelating ion exchange resin is Amberlite™ IRC747, which is commercially available from DuPont. Amberlite™ IRC 747 is a macroreticular styrene / divinylbenzene resin bead which contains alkylaminophosphonic groups.

[0087] Post brine concentration

[0088] The devices employed in the post brine concentration process are not specifically limited, provided that they can operate to evaporate or electrodialyze a solution at high temperatures, such as T > 40°C. For example, suitable apparatus for an evaporation includes one or more pieces of equipment selected from a mechanical vapor recompression MVR) evaporator, a single-effect evaporator, a multiple-effect evaporator, and a flash evaporator. Preferably, the evaporation is conducted via an MVR evaporation device. The MVR evaporator may include an MVR falling film evaporator or an MVR forced circulation type, or both. The electrodialysis unit may include a cathode and an anode. Between the cathode and the anode is a cation transfer membrane and an anion-transfer membrane. This forms two concentrate compartments and a center product compartment.

[0089] The stream that enters the post brine concentration system may have a lithium ion concentration higher than 0.5% (wt lithium), or preferably, higher than 1% (wt lithium). The stream that leaves post brine concentration system contains lithium ion concentration could be higher than 1.5 or 2% (wt lithium), or preferably, higher than 2 or 2.5% (wt lithium). The weight percentages of lithium ions are based on the total weight of the respective stream.

[0090] Boron removal

[0091] Boron, for example in the form of boric acid or borates or both, is one of the contaminants that needs to be removed during downstream processing steps of the lithium-enriched concentrate stream, after reverse osmosis / nanofiltration processing, to achieve final lithium product quality. In addition to using semi permeable membrane at specific pH to reject or pass boron, another method to remove boron from the lithium enriched concentrate stream is to use a boron selective chelating ion exchange resin at a temperature above 40°C, or preferably between 60 and 80°C to reduce the concentration of boron-containing species. The lithium containing concentrate stream passes through a resin bed that is filled with boron removal ion exchange resin, in a fixed bed or a packed bed, or in a continuous ion exchange process, such as for example a continuous countercurrent ion exchange (CCIX) design or another suitable design. In a preferred embodiment, the boron removal ion exchange resin is Amberlite™ IRC743, which is commercially available from DuPont. Amberlite™ IRC 743 is a polyol macroreticular resin based on a styrene / divinylbenzene copolymer which is aminated using N-methyl-glucamine.

[0092] Precipitation

[0093] In some preferred embodiments, the product of the lithium extraction process described herein is a solid. Preferred solid lithium products include, without limitation, lithium salts, for example lithium carbonate. The solid lithium product may be prepared by dosing reactant into the lithium enriched permeate solution, preferably at temperature above 40°C, or more preferably between 60 and 80°C. Suitable reactants include but are not limited to sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, other soluble carbonate and bicarbonate salts, and the like. After reaction and precipitation, the solid lithium product may be separated from the supernatant solution by technologies including sedimentation, filtration, centrifugation, etc. The solid lithium product may be washed with deionized water or another washing liquid that does not contain impurities that may impact product quality. The washed solid lithium product may be dried in one or more appropriate drying devices. The dried solid lithium product may be ground or granulated by conventional means to obtain a suitable particle size range, as required by the product's application and the specifications for its end use.

[0094] The following examples are provided to describe the invention in further detail. These examples, which set forth specific embodiments and a preferred mode presently contemplated for carrying out the invention, are intended to illustrate and not to limit the invention.

[0095] EXAMPLES

[0096] Example 1 -Lithium adsorbent making

[0097] A lithium adsorbent was synthesized according to the methods described by U.S. Pat. No. 11371118. In brief, 1 liter of resin was covered with water to make total volume of 1200 mL. 200 mL of concentrated HCI was added; the mixture was stirred and allowed to stand overnight. Fluid was drained from the mixture using vacuum filtration, and the resin was repeatedly rinsed with water. Resin was mixed with 1.5 L 30 wt% AICU solution and stirred. Resin was drained using vacuum filtration. 1 L of aqueous 30% by weight ammonia solution was added to the resin and stirred, then drained using vacuum filtration, followed by washing with water. 1 L of 0.1N ammonium chloride was added to the resin and stirred, and the pH of the supernatant liquid was adjusted to 10.5 to 11 with aqueous IN NaOH, followed by washing with water. 25 mL of IN NaOH and water were added, to give total volume of 1.6 L. The mixture was allowed to stand for 16 to 24 hours and then the resin was washed with water. Then 2NaAIO?-NaOH was added in six successive lots of 167 g each. An aqueous solution of 36 wt% HCI was added continuously. The resin was then washed with water. The resin was washed with 1.5 L aqueous 26% by weight solution of NaCI then stored in a reactor. Then 250 g LiCI was added; the mixture was stirred and then placed in an oven at 95° C. for 16 hours. At this point salt (a) was deposited onto the resin. Salt (a) is LiX-2AI(OH)3-nH2O, where X is a halogen ion, and n is the number of water molecules of hydration, wherein 0 n 10. The number n may be an average value over multiple molecules of salt (a). Then aqueous 26% by weight NaCI was added to make total volume of 2.2 L. The mixture was heated to 70° C and 60 g of solid NH4CI was added. The resin was titrated with aqueous 36% HCI followed by IN HCI to pH 5, then isolated by filtration to provide the lithium adsorbent used in the Examples below.

[0098] Example 2 -Lithium adsorption and desorption

[0099] Adsorption: 30 ml lithium adsorbent was loaded into a column. The Li-containing brine was a water solution containing the following solutes: 1.27 g / L LiCI, 92.58 g / L NaCI, 35.56 g / L MgCL, 7.55 g / L CaCL, 3.87 g / L K2SO4 and 2.44 g / L H3BO3. This brine was injected from the top of the column and passed through the column at a rate of 6 BV / hr at 400C. After 30 bed volume (BV) of brine passed through the column, the liquid was drained out of the column, leaving liquid level of 1 cm over the resin top surface.

[0100] Desorption: The resin was rinsed with 2 BV of DI water at 12 BV / hr at 25 ° C. Then the resin in the column was heated to 40, 50, 60, 70 and 80° C. An aqueous solution of LiCI having 100 ppm by weight lithium was also heated to 40, 50, 60, 70 and 80° C. At each column temperature, the aqueous LiCI solution of the same temperature was loaded onto top of the column and passed through the column at 2 BV / hr for 5 BV. Desorption samples were collected every 0.2 BV and analyzed for lithium content.

[0101] Example 3 -NF membrane separation on Li / Mg solution

[0102] A commercially available piperazine-based nanofiltration membrane (Made in FILMTEC, Edina, Minnesota; available from DuPont de Nemours, Inc., of Wilmington, DE (hereinafter "DuPont")) was rolled into 1812 size element for performance test. The 1812 element had a 3-envelope design. Each flat sheet was cut into 500 mm x 255 mm size. After glue application the active flat sheet area of the full element was 0.55 m2. The mixed salt feed solution was prepared with 3000 ppm LiCI and 15000 ppm MgCI2at various temperature and pH values, as shown in the table below. The permeate flow was maintained at 190 to 210 ml / min, which was equal to a permeate flux rate of 20-23 L / m2-h. The element recovery was 10%, which means the permeate flow was 10% of feed flow in this experiment, which mimicked the operation of an industrial nanofiltration system.

[0103]

[0104] The Li / Mg separation results are shown in the below table. As the temperature increased, both the Mg passage and Li passage increased. As the pH decreased, the Mg passage decreased and Li passage increased. Comparing with conventional operation (Experiment 1# as control group at 25 °C and pH 7), the permeate / feed ("P / F") Li / Mg ratio increased from 4.06 in Experiment 1# to 14.24 in experiment 12# at 55 °C and pH 3. It is also demonstrated that the Li passage was enhanced from 134.2% to 186.2%, and the Mg passage was reduced from 33% to 13.1%, from experiment lit to experiment 12#. The commercially available nanofiltration membrane FILMTEC™ LiNE-XD 4040 (Made in FILMTEC, Edina, Minnesota; available from DuPont) was used for separation of monovalent ions and divalent ions. The mixed salt feed solution was prepared with 1800 ppm LiCI and 25000 ppm MgCL at various temperatures and pH levels, as shown in the table below. The permeate flow was maintained at 2.6 L / min, which corresponded to 20-21 L / m2-h permeate flux rate. The element recovery was 17-18%, which means the permeate flow was 17-18% of feed flow in this experiment, which mimicked the operation of an industrial nanofiltration system. The Li / Mg separation results are shown in the below table. As the temperature increased, both the Mg passage and Li passage increased. As the pH decreased, the Mg passage was reduced and Li passage increased. Comparing with conventional operation (Experiment l# as control group at 25 °C and pH 7), the permeate / feed ("P / F") Li / Mg ratio increased from 52.7 in Experiment 1# to 92.4, in experiment 12# at 55 °C and pH 3. These results also demonstrate that the Li passage was maintained and was not significantly reduced at 155% to 154%, and that the Mg passage was reduced from 2.95% to 1.67%, from experiment 1# to experiment 12#.

[0105] Example 4 - Multiple passes nanofiltration ("NF") separation

[0106] A commercially available piperazine-based nanofiltration membrane (Made in FILMTEC, Edina, Minnesota; available from DuPont) was rolled into 1812 size element for performance testing. The 1812 element had a 3-envelope design. Each flat sheet was cut into 500 mm x 255 mm size, after glue application the active flat sheet area of the full element was 0.55 m2. The mixed salt feed solution was prepared with LiCI and MgCL to mimic the composition of the desorption stream. The permeate flow was maintained at 190 to 210 ml / min, which is equal to a permeate flux rate of 20 to 23 L / m2-h. The element recovery was 10%, which means the permeate flow was 10% of feed flow in this experiment, to mimic the operation of an industrial nanofiltration system.

[0107] For the "2 passes NF" experiment, the permeate composition of the first pass was analyzed and re-formulated as the feed composition of the second pass NF. The permeate flux of second pass NF was 260 ml / min, and element recovery was 10%, to mimic the operation of an industrial nanofiltration system.

[0108] In the conventional design at 25 °C, the single pass NF Li / Mg selection ratio was 30.38. Although at higher temperature the divalent ion rejection declined (as shown in Example 3), the 2 passes NF design successfully further rejected magnesium ion and passed lithium ion through the NF membrane. The 2 passes NF had an even higher Li / Mg selection ratio with 174.8 at 55 °C, higher than 25 °C with single pass design, but lower than 25 °C, two passes design.

[0109] Example 5 -Mg removal by Amberlite™ IRC747UPS resin 20 ml chelate resin of Amberlite™ IRC747UPS with amino-phosphonic groups (available from

[0110] DuPont) was loaded into a column. A brine feed with 110 ppm Mg2+and 2000 ppm Li+was injected from the top of the column and passed through the column at a rate of 20 BV / hr at 40 ° C and 60 ° C respectively. Treated solution was collected every 4.5 BV and analyzed for Mg content. After 120 BV of brine passed through the column, the liquid was drained out of the column, leaving liquid level of 1 cm over the resin top surface. The results are shown in the table below. The Mg2+breakthrough was set at O.lppm. Chelate resin exhibited higher Mg2+removal service throughput at 60 ° C than that at 40° C.

[0111] Table 1. Mg removal at 40 ° C and 60 ° C with feed containing 110 ppm Mg and 2000 ppm Li. Example 6 -Boron removal by Amberlite™ IRA743 resin

[0112] 30 ml chelate resin of Amberlite™ IRA743 with N-methylglucamine groups (available from DuPont) was loaded into a column. A feed with 220 ppm B3+as boric acid and borate salts and 28000 ppm Li+was injected from the top of the column and passed through the column at a rate of 4 BV / hr at 40 ° C and 60 ° C respectively. Treated solution was collected every 2 BV and analyzed for B3+content. After 24 BV of brine passed through the column, the liquid was drained out of the column, leaving liquid level of 1 cm over the resin top surface. The results are shown in Table 2. The B3+breakthrough was set at 10 ppm. Operation temperature shows no significant impact on service throughput for B3+removal according to obtained results.

[0113] Table 2. Mg removal at 40 ° C and 60 ° C with feed containing 220 ppm Mg and 28000 ppm Li.

[0114] While certain of the preferred embodiments of the present invention have been described and specifically exemplified above, it is not intended that the invention be limited to such embodiments. Rather, it is to be understood that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

WHAT IS CLAIMED IS:

1. A process for extracting lithium from a source of dissolved lithium, said process comprising the steps of:(A) providing a lithium source that comprises dissolved lithium ions and one or more impurities;(B) passing the lithium source through an adsorbent bed, said adsorbent bed comprising an adsorbent matrix, at a temperature of 40°C or lower to extract the lithium from the lithium source onto the adsorbent matrix;(C) passing a desorption media through the adsorbent bed at a temperature above 40°C, wherein the desorption media comprises pure water or a dilute aqueous solution of a lithium salt, to obtain a lithium rich eluent;(D) adjusting the pH of the lithium rich eluent to below 6.0;(E) processing the lithium rich eluent through a pressurized semi permeable membrane system at temperature above 40°C, said membrane system comprising at least one nanofiltration membrane and at least one reverse osmosis membrane, wherein a majority of the lithium ions or water of the lithium rich eluent passes through one nanofiltration membrane at least twice or through two or more nanofiltration membranes, to produce a permeate that is depleted in lithium and a brine that is enriched in lithium and depleted in divalent ions; and(F) including at least a portion of the permeate at a temperature above 40°C in the desorption media.

2. The process of claim 1, wherein the impurities comprise one or more of Na+, Ca2+, Mg2+, silica and boron.

3. The process of claim 1 or claim 2 wherein the adsorbent bed is selected from the group consisting of a fixed bed, a packed bed, a continuous countercurrent ion exchange (CCIX), a continuous ion exchange (CIE), and a continuous adsorption / desorption (CAD) apparatus.

4. The process of any of claims 1, 2, or 3, wherein the semi permeable membrane system is configured by connecting two or more of the nanofiltration membrane units or reverse osmosis membrane units in series; or wherein the semi permeable membrane system is configured by connecting two or more of the nanofiltration membrane units or reverse osmosis membrane units in parallel.

5. The process of any preceding claim, wherein the brine is treated by a chelating ion exchange resin bed at temperature above 40°C to reduce the concentration of divalent cations.

6. The process of any preceding claim, wherein the brine is passed through a bed of boron selective ion exchange resin at temperature above 40°C, to reduce the concentration of boron-containing species.

7. The process of any preceding claim, wherein the brine is further concentrated at a temperature above 40°C using one or more of a thermal multiple effect evaporator, a mechanical vapor compressor, or electrodialysis.

8. The process of any preceding claim, wherein one or more lithium salts are precipitated from the brine at temperature above 40°C.

9. The process of claim 8, wherein the precipitation is effected by dosing the brine with a carbonate salt.

10. The process of claim 8 or claim 9, wherein the precipitation is effected by dosing the brine with a carbonate salt to obtain precipitated lithium carbonate.

11. The process of any of any preceding claim, or of any of claims 1 through 8, wherein the lithium salt in the brine is converted by electrodialysis to lithium hydroxide, and solid lithium hydroxide is isolated from the brine by crystallization.

12. The process of any preceding claim, wherein said adsorbent comprises one or more of aluminum / lithium intercalate, manganese, and titanium.

13. The process of any preceding claim, wherein said adsorbent further comprises a polymer matrix, and said polymer matrix comprises one or more polymers selected from the group consisting of polystyrene, polyacrylic acid, and polyvinyl chloride.

14. The process of any preceding claim, wherein at least 50% of the lithium in the lithium source is extracted into the adsorbent.

15. The process of any preceding claim, wherein said desorption media comprises a dilute lithium halide solution.

16. The process of any preceding claim, wherein the desorption media has a lithium chloride concentration below 1000 ppm and a temperature above 40°C.

17. The process of any preceding claim, wherein said lithium rich eluent has a lithium concentration in the range of about 200 ppm to about 10000 ppm.

18. The process of any preceding claim, wherein said lithium rich eluent comprises divalent cations M2+ in solution, in a weight ratio of dissolved M2+:Li+ in the range of about 0.1:1 to 100:1 wt / wt, wherein M2+ comprises calcium ions, magnesium cations, or calcium ions and magnesium cations.

19. The process of any preceding claim, wherein the nanofiltration membrane(s), the reverse osmosis membrane(s), or both the nanofiltration membrane(s) and the reverse osmosis membrane(s) comprise polypiperazine or polyamide.

20. The process of any preceding claim, wherein the semi permeable membrane system is composed by nanofiltration and reverse osmosis units, each of which has a feed inlet, a concentrate outlet, and a permeate outlet, and wherein the concentrate outlet volumetric flow is less than 70% of the feed inlet volumetric flow, and the permeate outlet volumetric flow is more than 30% of the feed inlet volumetric flow.

21. The process of any preceding claim, wherein the desorption media is prepared by the permeate stream of the reverse osmosis units; the permeate stream for the desorption media preparation contains dilute lithium halide, with the concentration of lithium halide less than 1000 ppm; and wherein the temperature of permeate stream and desorption media preparation is above 40°C.

22. A process for extracting lithium from a source of dissolved lithium, said process comprising the steps of:(A) providing a lithium source comprising the dissolved lithium ion or a lithium- containing molecule and one or more impurities, such as, without limitation, Na+, Ca2+, Mg2+, dissolved silicates, or boron;(B) passing the lithium source through a bed of adsorbent at the ambient temperature of the lithium source, for example an adsorbent comprising an aluminum / lithium element, or manganese, or titanium, to extract lithium ion from the lithium source onto the adsorbent;(C) rinsing the adsorbent bed with desorption media at temperature above 40°C, wherein the desorption media comprises pure water or a dilute aqueous salt solution, for example a dilute lithium halide solution, to obtain a lithium rich eluent;(D) adjusting the pH of the lithium rich eluent to below 6.0;(E) subjecting the lithium rich eluent from step (D) to a pressurized semi permeable membrane system at a temperature above 40°C, wherein the membrane system includes a nanofiltration membrane and a reverse osmosis membrane, to selectively remove divalent ions and to increase the lithium concentration of the solute;(F) optionally passing the solute through at least one nanofiltration membrane that rejects divalent ions, for example the nanofiltration membrane of step (E), wherein a majority of the lithium ions and water of the lithium rich eluent passes through one nanofiltration membrane at least two times or through two or more nanofiltration membranes;(G) optionally passing the solute through at least one reverse osmosis membrane that rejects soluble ions and neutral organic molecules, for example the reverse osmosis membrane of step ( E ), wherein a majority of the water molecule passes through one reverse osmosis membrane at least one time or through one or more reverse osmosis membranes;(H) using the permeate stream generated by the reverse osmosis membrane in the semipermeable membrane system at a temperature above 40°C as at least a portion of the desorption media for lithium adsorbent bed desorption in step (D).

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