Lithium extraction methods

Abstract

A method and apparatus for lithium-ion extraction are provided. The method includes passing a lithium-containing brine solution through a lithium adsorbent, followed by passing a desorption medium through the lithium adsorbent at a temperature above 40°C to produce a lithium-rich 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. This method is energy efficient because it is carried out entirely at temperatures above 40°C. Therefore, it is not necessary to lower the temperature of the lithium-rich eluent before passing it through the nanofiltration membrane and the reverse osmosis membrane. Furthermore, it is not necessary to raise the temperature of the nanofiltration / reverse osmosis permeate as a desorption medium before passing it through the lithium adsorbent, nor is it necessary to raise the temperature of the lithium-rich stream before lithium precipitation.

Description

Cross-reference to related applications

[0001] This application is based on 35 USC 365(c) claims priority to International Application No. PCT / CN23 / 140173, filed on 20 December 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This article provides a method for selectively extracting lithium from natural or industrial brine reservoirs. More specifically, the method extracts lithium from natural or industrial brine by contacting an aqueous brine solution with an adsorbent, membrane, ion exchange resin, etc. Background Technology

[0003] This specification references several patents, patent applications, and publications to provide a more comprehensive description of the prior art to which this invention relates. The full disclosure of each of these patents, patent applications, and publications is incorporated herein by reference.

[0004] 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. Global demand for lithium is expected to increase in the foreseeable future. Currently, industrial-scale Li extraction technologies employ chemical processing followed by evaporation-based processes to recover lithium from various natural and recycled sources. This is a time-consuming and space-consuming operation. Furthermore, significant amounts of water are required for Li recovery, and most natural Li sources are located in arid regions with limited clean water supplies. To accelerate the evaporation process and recover water, engineered processes such as thermal evaporation followed by condensation have been applied, but these remain energy-inefficient.

[0005] Various membrane-based methods for recovering lithium from natural and recycled sources have been described. U.S. Patent No. 10,450,633 ('633) describes a membrane-based method for recovering Li from an acidic solution. The processing steps described in '633 involve passing an acidic lithium solution through a nanofiltration membrane unit, wherein a portion of the acid and lithium solution permeates through the nanofiltration membrane. U.S. Patent No. 6,004,464 describes a method for recovering brine from a water softening resin unit, comprising acidifying a chloride-containing brine to a pH range of 0.5-6 and then adding a salt having a monovalent cation and a polyvalent anion (e.g., Na₂SO₄) to the pH-adjusted brine. CN 112,850,851 describes a method for separating Li from Na₂SO₄-type brine from a salt lake, involving adding a chloride (Cl⁻) salt to the brine and pumping it through a nanofiltration system in a pH range of 7.5-11.0 to obtain excellent Li. + / Mg2+ Separation. CN 108,063,295 describes a method for extracting Li and other heavy metals from a battery source using hydrochloric acid, wherein Li₂SO₄ is added to the acidic feed to react under stirring for about 30 minutes to generate LiCl and CaSO₄, which are then further separated using a nanofiltration membrane. US Patent No. 10,604,414 describes a method for recovering lithium from geothermal brine using ion exchange and reverse osmosis methods. International Patent Application Publication No. WO 2023 / 058548 describes a method for recovering monovalent metal ions from a solution containing monovalent and polyvalent metal ions using a nanofiltration membrane unit and a reverse osmosis membrane unit. US Patent No. 10,648,061 describes introducing and removing a lithium source into a bed of adsorbent composed of hydrated alumina intercalated with lithium halides; washing the adsorbent bed to obtain a lithium eluent with an increased lithium concentration; and treating the eluent by nanofiltration and forward osmosis. U.S. Patent Application Publication No. 2022 / 0380223 describes liquid solution concentration methods and related systems involving permeation units and energy recovery. These methods and systems may include features such as balancing streams, recirculating streams, and / or regulating valves, which, individually or in combination, can provide improved energy efficiency and / or system performance. U.S. Patent Application Publication No. 2022 / 00055910 describes a method for separating lithium as lithium hydroxide or lithium carbonate via adsorption / desorption and other purification methods. Various streams (including some lithium-containing streams) are recycled to the adsorption / desorption process.

[0006] In many known lithium extraction methods (including several described in the publications cited above), permeate from 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 lower; however, it is usually heated to a temperature between 40°C and 70°C before eluting lithium from the adsorbent. The temperature of the eluted stream is then typically lowered to 35°C or lower before further purification via reverse osmosis. These temperature adjustments result in unnecessary energy waste in lithium extraction methods. For example, Nilsson et al. found that retention rates of nanofiltration membranes typically decrease with increasing temperature. (“The influence of pH, salt and temperature on nanofiltration performance,” Journal of Membrane Science 312 (2008) 97–106).

[0007] Clearly, there is still a need for more efficient lithium extraction methods, especially those that offer good yields and excellent energy efficiency. Summary of the Invention

[0008] Therefore, this paper provides a method for extracting lithium from a feed brine solution, or "lithium source." This method incorporates a combination of separation techniques to extract lithium from the feed brine solution with higher efficiency, lower energy consumption, and higher returns based on water and energy utilization. This method can produce lithium salt aqueous solutions or lithium salt solids with high purity and high extraction yield.

[0009] The brine solution can be natural brine, synthetic industrial brine, or a combination thereof, such as continental brine, geothermal brine, salt lake brine, oilfield brine, brine from hard rock lithium deposits, brine extracted from lithium-containing materials (such as recycle lithium-containing equipment), or a combination of two or more thereof.

[0010] This method may include the following steps: removing impurities from an aqueous brine solution and concentrating lithium in the brine solution using a lithium adsorbent, eluting lithium from the adsorbent to produce a lithium-rich stream, and then recovering lithium from the lithium-rich stream. In some cases, the enrichment level may be such that the lithium-rich stream is considered purified.

[0011] The method may also include the following steps: removing divalent impurities from a lithium-rich stream by using a nanofiltration membrane to form a lithium-purified stream and a divalent-concentrated stream with less lithium.

[0012] The method may also include the following steps: concentrating lithium and dehydrating the lithium-rich 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.

[0013] Lithium adsorbents can be designed with fixed beds, packed beds, or continuous ion exchange processes (such as continuous countercurrent ion exchange (CCIX)) or other suitable designs. Lithium adsorbents can include any material known for adsorbing lithium or lithium ions, such as lithium aluminum intercalators prepared from hydrated aluminum, lithium aluminum layered double hydroxide chlorides, layered double hydroxide-modified activated alumina, layered double hydroxide-embedded ion exchange resins or copolymers or molecular sieves or zeolites, layered aluminate polymer blends, lithium manganese oxides, titanium oxides, immobilized crown ethers, or combinations of two or more thereof.

[0014] More specifically, the method described herein includes the following steps:

[0015] (A) Provide a lithium source comprising dissolved lithium ions or lithium-containing molecules and one or more impurities, such as, but not limited to, Na. + Ca 2+ Mg 2+ Dissolved silicates or boron;

[0016] (B) Passing the lithium source through an adsorbent, such as a bed of adsorbents containing aluminum / lithium or manganese or titanium, at the ambient temperature of the lithium source, to extract lithium ions from the lithium source onto the adsorbent.

[0017] (C) The adsorbent bed is flushed with a desorption medium at a temperature above 40°C, wherein the desorption medium includes pure water or a dilute salt solution, such as a dilute lithium halide solution, to obtain a lithium-rich eluent.

[0018] (D) Adjust the pH of the lithium-rich eluent to below 6.0;

[0019] (E) subject the lithium-rich eluent from step (D) to a pressurized semi-permeable membrane system at a temperature above 40°C, wherein the membrane system comprises a nanofiltration membrane and a reverse osmosis membrane to selectively remove divalent ions and increase the lithium concentration.

[0020] (F) Optionally, the solute is passed through at least one nanofiltration membrane that retains divalent ions, such as the nanofiltration membrane of step (E), wherein most of the lithium ions and water of the lithium-rich eluent pass through a nanofiltration membrane at least twice or through two or more nanofiltration membranes.

[0021] (G) Optionally, the solute is passed through at least one reverse osmosis membrane that rejects soluble ions and neutral organic molecules, such as the reverse osmosis membrane of step (E), wherein most water molecules pass through a reverse osmosis membrane at least once or through one or more reverse osmosis membranes; and

[0022] (H) Using the permeate stream generated by the reverse osmosis membrane in the semi-permeable membrane system at a temperature above 40°C as at least a portion of the desorption medium for the desorption of the lithium adsorbent bed in step (D).

[0023] The above method is typically used for primary lithium extraction from an aqueous brine solution containing at least 10 ppm of lithium ions. This method may further include one or more of the following optional steps (OS):

[0024] (OS1) Following step (E), the purified lithium-containing stream is treated at a temperature above 40°C through an ion exchange resin bed, preferably a chelating resin, to remove residual divalent cations, such as Ca. 2+ or Mg 2 + ;

[0025] (OS2) After step (E), the purified lithium-containing stream is treated with an ion exchange resin bed at a temperature above 40°C, which is preferably a chelating resin, to selectively remove boron substances, such as boric acid or borate.

[0026] (OS3) After step (E), the purified lithium-containing stream undergoes a concentration step at a temperature above 40°C to increase the lithium ion concentration in the solution, for example, using one or more of a thermal multi-effect evaporator, a mechanical vapor compressor, or electrodialysis.

[0027] (OS4) Following step (E), the purified lithium-containing stream is precipitated at a temperature above 40°C by adding an anion of carbonate or another lithium salt with lower solubility to convert the dissolved lithium ions into a solid form, for example, by metering the addition of sodium carbonate to obtain a lithium carbonate precipitate; and

[0028] (OS5) Following step (E), the purified lithium-containing stream is treated by electrodialysis to produce lithium hydroxide. Solid lithium hydroxide can then be obtained, for example, by crystallization or by a combination of techniques such as concentration and crystallization.

[0029] A first optional step (OS1) can be performed to remove divalent impurities from the lithium-rich stream at the outlet of the semipermeable membrane system. Before OS1, the amount of divalent impurities in the lithium-rich stream at the outlet of the semipermeable membrane system can be in the range of 10 ppm to 5000 ppm. After the OS1 step, the amount of divalent impurities is reduced to less than 1 ppm, and preferably less than 0.1 ppm or 0.02 ppm.

[0030] A second optional step (OS2) can be performed to remove boron impurities from the lithium-rich stream at the outlet of the semipermeable membrane system. Prior to OS2, the amount of boron in the lithium-rich stream at the outlet of the semipermeable membrane system can be in the range of 10 ppm to 5000 ppm, as measured by inductively coupled plasma (ICP) as elemental boron. After the OS2 step, the amount of boron is reduced to less than 10 ppm, and preferably less than 5 ppm or less than 1 ppm, as again measured by ICP as elemental boron.

[0031] A third optional step (OS3) can be performed to dehydrate the lithium-rich solution, thereby increasing the lithium concentration. This increase in lithium concentration is beneficial if the final product is expected to require such a high concentration solution, or if a fourth optional step (OS4) chemical precipitation method is used to obtain a solid form of lithium product. A semi-permeable membrane can increase the lithium concentration from 100 or 5000 ppm to 10000 or 15000 ppm (wt lithium). The OS3 step can further concentrate the concentration to 20000 ppm, 30000 ppm, or 35000 ppm (wt lithium).

[0032] A fourth optional step (OS4) can be performed to convert dissolved lithium ions into a solid salt, such as solid lithium carbonate, by metering the addition of a carbonate, such as sodium carbonate, so that lithium carbonate will precipitate.

[0033] A fifth optional step (OS5) can be performed to produce lithium hydroxide. Lithium hydroxide (LiOH) is the primary lithium salt used in the production of nickel-rich cathode materials. Electrodialysis is a promising method for producing lithium hydroxide from lithium-rich solutions, and this has been widely 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; its link is to https: / / doi.org / 10.1021 / ie404334s Solid lithium hydroxide can be obtained from a lithium hydroxide solution produced by electrodialysis (e.g., by crystallization).

[0034] The advantages and features characterizing the novelty of the invention are specifically pointed out in the appended claims and form a part of the claims. However, for a better understanding of the invention, its advantages, and the purposes achievable through its use, reference should be made to the accompanying drawings, which form another part of the invention, and to the accompanying descriptive text, in which one or more preferred embodiments of the invention are shown and described. Attached Figure Description

[0035] The invention will now be described with reference to the accompanying drawings, in which:

[0036] Figure 1 This is a schematic diagram of a first apparatus suitable for practicing the method of the present invention.

[0037] Figure 2A , Figure 2B and Figure 2C This is a schematic diagram of another apparatus suitable for practicing the method of the present invention. Detailed Implementation

[0038] lithium adsorbent

[0039] Any lithium adsorbent known in the art is suitable for use in the methods described herein. Some suitable adsorbents and methods for synthesizing adsorbents are described, for example, in U.S. Patent Nos. 11,371,118 and 4,348,296. These patents describe a method for manufacturing aluminum / lithium complexes based on organic or inorganic matrices. Alternatively, suitable aluminum / lithium complexes can be made from aluminum sources such as gibbsite, diaspore, gibbsite, bauxite, or other aluminum-containing minerals.

[0040] In a more preferred embodiment, the lithium adsorption medium comprises a particulate composition, which further comprises an aggregate of resin beads and LiX·2Al(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 a polymer having 0.5 to 3 equivalents of amine side groups per liter of particulate composition; wherein the resin beads have an average pore size of 5 to 100 nm; wherein the aggregate of resin beads has a harmonized average particle size of 200 to 1000 micrometers; wherein the aggregate of resin beads has a particle size of 20 to 150 μm. 2 / g surface area; and wherein aluminum is present in an amount of 14.5% by weight or higher of aluminum atoms based on the total weight of the particulate composition. In a more preferred embodiment, the resin beads have all of these properties.

[0041] Lithium adsorption and desorption

[0042] Lithium adsorption is carried out by passing a lithium-containing brine source through a bed of lithium adsorbent containing a lithium adsorption medium. Lithium adsorption can be performed at temperatures below 40°C, such as 35°C or below, 30°C or below, 27°C or below, 25°C or below, or at ambient temperature. Lithium ions are adsorbed onto the solid-based adsorbent, and the aqueous liquid exits the adsorbent bed with a reduced lithium ion concentration. The lithium adsorbent can adsorb lithium ions from a lithium-containing brine source with any lithium concentration, with a preferred lithium concentration in the brine source being higher than 10 ppm. Higher lithium concentrations in the brine solution will result in a higher lithium ion loading in the adsorbent.

[0043] Lithium adsorbents can be loaded into fixed or packed beds, or into continuous ion exchange units (such as continuous countercurrent ion exchange (CCIX) units), continuous adsorption / desorption, or other suitable designs. The adsorption process is stopped and the desorption step is prepared when lithium ions in the lithium-rich effluent permeate the adsorbent bed. Lithium ions in the fluid passing through the adsorbent bed can be detected using conventional methods (such as ICP). Alternatively, the lithium concentration of the lithium source and the lithium-ion capacity of the adsorbent bed can be determined. Using this information, adsorption can be stopped when a certain volume of lithium source containing the lithium-ion capacity of the adsorbent bed flows through the bed. If the flow rate of the lithium source is also known, adsorption can be stopped after a fixed adsorption time.

[0044] The lithium desorption step is carried out by introducing the desorption medium into the adsorbent bed after the lithium adsorption step. The temperature of the desorption medium is between 40°C and 100°C, and preferably between 60°C and 80°C. The higher the temperature of the desorption medium, the higher the lithium desorption efficiency and the higher the lithium concentration in the adsorbate. However, there is a significant temperature above which no benefit to desorption is obtained. At these excessively high temperatures, heat is dissipated into the atmosphere. Therefore, the maximum desorption temperature is set based on the engineering environment and the heat loss rate. Furthermore, the higher the desorption temperature, the higher the temperature of the fluid entering the semi-permeable membrane system. Therefore, at these higher temperatures, the entire lithium extraction apparatus has a high temperature gradient between the processing fluid and the surrounding environment, and thus a high heat loss rate. However, advantageously, in the method described herein, carried out at a temperature between 40°C and 100°C, and preferably between 60°C and 80°C, it is not necessary to waste energy by raising the temperature of the desorption medium before eluting lithium from the adsorbent bed or by lowering the temperature of the lithium-rich eluent before the reverse osmosis / nanofiltration process. There is no need to waste energy by raising the temperature of the lithium concentrate stream after the semi-permeable system and before the lithium precipitation step.

[0045] The desorption medium can be deionized water or a dilute salt solution, such as a dilute lithium solution. A small amount of lithium ions in the desorption medium may be beneficial for higher desorption efficiency. The lithium ion concentration in the desorption medium can be below 1000 ppm, and preferably between 50 and 500 ppm. It is worth noting that the entire system described herein (including the desorption of lithium from the adsorbent bed and the semi-permeable membrane system) operates at high temperatures, i.e., at 40°C or above. However, reverse osmosis membranes have higher ion permeability at high temperatures than at room temperature, and therefore it is expected that the reverse osmosis permeate from the semi-permeable membrane system will contain a small amount of lithium ions. In fact, it is not necessary for the reverse osmosis permeate to be very purified water or deionized water. The amount of lithium ions in the reverse osmosis permeate can be below 1000 ppm, and preferably between 50 and 500 ppm, to allow the permeate to function effectively as a desorption medium.

[0046] The lithium-rich eluent after desorption of the adsorbent is collected for use in the next processing step. Preferably, the lithium concentration after desorption is between 100 or 200 and 10,000 ppm, and more preferably between 200 or 500 ppm and 2,000 or 3,000 ppm.

[0047] Lithium separation and concentration

[0048] High-quality final lithium products are typically used as feedstock in lithium-ion battery manufacturing or for other industrial applications, such as glass, ceramics, lubricants, or organic synthetic materials. Such high-quality lithium products may require downstream processing steps after elution from lithium adsorbents to remove any residual impurities and further increase the lithium concentration. Impurities present in the lithium-rich eluent prior to downstream processing may include Ca. 2+ Mg 2+ One or more of dissolved silicates and boron, etc. The concentration of divalent cation 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 increase from hundreds or thousands of ppm to more than 10,000 ppm (wt lithium), or preferably more than 20,000 or 25,000 ppm (wt lithium).

[0049] The methods described herein for lithium separation and concentration of lithium-rich effluents are accomplished through an integrated approach combining, but not limited to, nanofiltration and reverse osmosis, and optionally hardness / boron removal ion exchange resins, thermal evaporators, and lithium precipitation. All steps described above are operated at one or more temperatures above 40°C. The goal of downstream processing is to obtain high-purity lithium products while minimizing processing costs such as raw material costs, energy consumption, and production loss.

[0050] semipermeable membrane

[0051] As used herein, the term "semi-permeable membrane" includes both reverse osmosis membranes and nanofiltration membranes. While various membrane configurations (e.g., hollow fiber, tubular, plate, and frame types) can be used, helical wound modules (which are interchangeably referred to herein as "helical wound elements") are preferred. Reverse osmosis membranes are relatively impermeable to almost all dissolved salts and typically retain more than about 95% of salts containing monovalent ions (such as sodium chloride). Reverse osmosis membranes also typically retain more than about 95% of inorganic molecules and organic molecules with molecular weights greater than about 100 Daltons. Nanofiltration membranes are more permeable than reverse osmosis membranes and typically retain less than about 95% of salts containing monovalent ions, while retaining more than about 35% (and often more than 50%, sometimes even more than 90%) of salts containing divalent ions, depending on the type of divalent ion and feed flow conditions such as temperature, pH, etc. These percentages are based on the weight percentage of the total weight of dissolved salts in the liquid fed to the semi-permeable membrane. Nanofiltration membranes typically also trap particles in the nanometer range as well as organic molecules with molecular weights greater than approximately 200 to 500 Daltons.

[0052] The construction of a spiral-wound module has been described in detail elsewhere (see, for example, U.S. Patent Nos. 6,881,336; 8,142,588; and 8,496,825). A spiral-wound membrane module can be formed by winding one or more membrane envelopes and optionally one or more feed channel spacers (“feed spacers”) around a permeate collection tube. Each membrane envelope preferably comprises two generally rectangular membrane sheets surrounding a permeate channel spacer (“permeate spacer”). This sandwich structure is secured together, for example, by a sealant along three edges, with a fourth edge abutting the permeate collection tube. The permeate spacer is in fluid contact with an opening in the permeate collection tube. The outer housing of the element can be constructed from a variety of materials, including stainless steel, tape, PVC, fiberglass, and epoxy resin. Additional details regarding the various components and constructions of helical wound elements are provided in the literature; see, for example: U.S. Patent No. 5,538,642, which describes a technique for attaching a permeate spacer to a permeate collection tube; U.S. Patent No. 7,951,295, which describes trimming operations and the use of UV adhesive for forming an insertion point seal; and U.S. Patent No. 7,875,177, which describes a suitable leaf-shaped package.

[0053] The membrane is not particularly limited and can be made of a variety of materials, such as cellulose acetate, polysulfone, polyethersulfone, polyamide, polyvinylidene fluoride, etc. Preferred membranes are composite structures having a discriminating layer formed by interfacial polymerization. A typical composite ultrafiltration membrane includes a backing layer (back side) of a nonwoven backing mesh (e.g., a nonwoven fabric, such as polyester fiber cloth available from Awa Paper Company in Tokushima Prefecture, Japan), an intermediate layer of a porous support having a typical thickness of about 25-125 µm, and a top discriminating layer (front side) of a thin-film polyamide layer having a thickness typically less than about 1 micrometer (e.g., 0.01 to 1 micrometer, but more commonly about 0.01 to 0.1 µm). The backing layer is not particularly limited, but preferably includes a nonwoven fabric or fiber mat containing fibers that may optionally be oriented. Alternatively, woven fabrics such as canvas can be used. Representative examples are described in U.S. Patent Nos. 4,214,994; 4,795,559; 5,435,957; 5,919,026; 6,156,680; US 2008 / 0295951 and U.S. Patent No. 7,048,855. Porous supports are typically polymeric materials with pore sizes sufficient to allow permeates to pass through substantially unrestricted but not large enough to interfere with the bridging of the thin-film polyamide layer formed thereon. For example, the pore size of the support preferably ranges from about 0.001 to 0.5 µm. Non-limiting examples of porous supports include those made from polysulfone, polyethersulfone, polyimide, polyamide, polyetherimide, polyacrylonitrile, poly(methyl methacrylate), polyethylene, polypropylene, and various halogenated polymers, such as polyvinylidene fluoride. Preferably, the separation layer is formed by interfacial polycondensation between polyfunctional amine monomers and polyfunctional acyl halide monomers on the surface of the microporous polymer layer, as described, for example, in U.S. Patent Nos. 4,277,344 and 6,878,278.

[0054] While modules are available in a variety of sizes, a common industrial reverse osmosis module has a standard 8-inch (20.3 cm) diameter and a 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 a permeate collection tube with an outer diameter of approximately 1.5 to 1.9 inches (3.8 cm–4.8 cm)).

[0055] One or more modules are arranged within a pressure vessel. The pressure vessel used in this invention is not particularly limited, but preferably comprises a solid structure capable of withstanding pressures associated with operating conditions. The vessel structure preferably includes a chamber having an inner periphery corresponding to the outer periphery of the helical module to be housed therein. The length of the chamber preferably corresponds to the combined length of elements (e.g., 1 to 8 elements) to be sequentially (axially) loaded, see US 2007 / 0272628. The pressure vessel may also include one or more end plates that seal the chamber once the module is loaded. 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; for example, both horizontal and vertical orientations can be used. Examples of suitable pressure vessels, module arrangements, and loading are described in: US Patent Nos. 6,074,595; 6,165,303; 6,299,772; and US 2008 / 0308504. Manufacturers of pressure vessels include Pentair of Minneapolis, Minnesota; Bekaert of Vista, California; and ROPV of Harbin, China.

[0056] Individual pressure vessels or a group of vessels working together (each equipped with one or more modules) are generally referred to as “units,” “skids,” “trains,” or “passes.” One or more vessels within a pass can be arranged in one or more stages, with each stage containing one or more vessels operating in parallel with respect to the feed fluid. Multiple stages are arranged in series, whereby the concentrated stream from an upstream stage is used as the feed fluid for a downstream stage, and the permeate from each stage can be collected without further reprocessing within the pass. Multi-stage ultrafiltration systems are constructed by interconnecting the individual stages along a fluid path, as described, for example, in U.S. Patent Nos. 4,156,645; 6,187,200; and 7,144,511.

[0057] Semi-permeable membrane systems (including nanofiltration and reverse osmosis membrane units) can be designed by connecting these units in series or parallel. This means that the concentrated and permeate streams from each reverse osmosis or nanofiltration column can be connected to another reverse osmosis or nanofiltration column to purify or concentrate a lithium stream. Suitable column connection schemes include, but are not limited to, those mentioned above. Figure 1 And the options depicted in Figure 2.

[0058] Referring now to the accompanying drawings, which are shown throughout the views, the same reference numerals denote corresponding structures, and particularly to... Figure 1 This demonstrates a system suitable for implementing the methods described herein. The components depicted in the accompanying figures are listed below:

[0059] (A) Water or another desorption medium from a pure water storage tank (PW) is delivered to a heat exchanger (HE) via a pipeline (TC0) and then passed through a lithium adsorbent bed (LA) via a desorbent stream (DS) to produce a lithium-rich eluent (TC1), which is connected to the feed side of a nanofiltration membrane (NF1) to separate divalent and monovalent ions, thereby producing a concentrated stream (TC3) containing concentrated divalent ions and reduced monovalent ions and a permeate stream (TC7) containing reduced divalent ions and monovalent ions with higher purity; the adsorbent bed (LA) is further equipped with a pipeline (LS1) for bringing a lithium source, such as brine, into the adsorbent bed (LA) and a pipeline (LS2) for returning brine (e.g., brine in which lithium ions have been adsorbed by the adsorbent bed (LA) and then leaving the adsorbent bed (LA)) to the lithium source.

[0060] (B) The lithium-rich eluent (TC1) is also connected to the feed inlet (TC2) of the reverse osmosis membrane (RO1) to retain ions, thereby producing a second concentrated stream (TC11) containing concentrated ions and a second permeate stream (TC15) containing reduced ion concentration.

[0061] (C) The concentrated stream (TC3) from the first nanofiltration membrane (NF1) is connected via line (TC4) to the second nanofiltration membrane (NF2) for further separation of divalent and monovalent ions (via permeate line TC18 and residue line TC19); or via line (TC5) to the second reverse osmosis membrane (RO2) to further increase the ion concentration (via permeate line (TC20) and residue line (TC21)); or via line (TC6) to the waste outlet for wastewater treatment or discharge; in addition, The permeate stream (TC7) of the first nanofiltration membrane (NF1) is connected via line (TC8) to the third nanofiltration membrane (NF3) for further separation of divalent and monovalent ions via permeate line (TC22) and residue line (TC23); or via line (TC9) to the third reverse osmosis membrane (RO3) to further increase the ion concentration (via permeate line (TC24) and residue line (TC25)); alternatively, the lithium-rich stream can be delivered via line (TC10) to the next step in lithium processing;

[0062] (D) The concentrated stream (TC11) from the first reverse osmosis membrane (RO1) is connected via line (TC12) to the fourth nanofiltration membrane (NF4) for further separation of divalent and monovalent ions (via permeate line (TC26) and residue line (TC27)); or via line (TC13) to the fourth reverse osmosis membrane (RO4) for further increasing the ion concentration (via permeate line (TC28) and residue line (TC29)); alternatively, the lithium-rich stream can be delivered via line (TC14) to the next step in lithium processing. The permeate stream (TC15) from the first reverse osmosis membrane (RO1) is connected via line (TC16) to the fifth reverse osmosis membrane (RO5) for further deionization of the water stream (via permeate line (TC30) and residue line (TC31)), or connected to the deionized water stream for desorption preparation (TC17).

[0063] (E) Connect one or more of the concentrated streams (TC19, TC23, or TC27) from the second, third, or fourth nanofiltration membranes (NF2, NF3, NF4) to a fifth nanofiltration membrane (not shown) for further separation of divalent and monovalent ions; or connect to a sixth reverse osmosis membrane (not shown) for further increase of ion concentration; or connect to a waste outlet (via line TC6, TC10, or TC14) for wastewater treatment or discharge; alternatively, one or more of the concentrated streams (TC19, TC23, or TC27) may be fully or partially recycled back to the upstream membrane (via one or more of FT1, FT10, FT2, FT3, FT4, FT5, FT6, FT7, and FT8). Connect one or more of the permeate streams (TC18, TC22, or TC26) from the second, third, or fourth nanofiltration membranes (NF2, NF3, NF4) to a seventh reverse osmosis membrane (RO7, see [link]). Figure 2A To further increase the ion concentration; or to be connected to a lithium-rich stream for further lithium processing (connection not shown); alternatively, one or more of the permeate streams can be fully or partially recycled back to the feed line of the semipermeable membrane (via one or more of FT1, FT10, FT2, FT3, FT4, FT5, FT6, FT7 and FT8).

[0064] (F) Connect the concentrated stream (TC21, TC25, TC29, or TC31) from the second, third, fourth, or fifth reverse osmosis membranes (RO2, RO3, RO4, RO5) to the sixth nanofiltration membrane (see [link to product]). Figure 2B To further separate divalent and monovalent ions; or to connect to the eighth reverse osmosis membrane (see Figure 2BTo further increase the ion concentration; or to connect to a lithium-rich stream for further lithium processing. The permeate stream from the second or third reverse osmosis membrane (TC20, or TC24, or TC28, or TC30) can be connected to a ninth reverse osmosis membrane (not shown) to further reduce the ion concentration; or for other purification treatments, or as a preparation step for the desorption medium; alternatively, one or more of the permeate streams can be fully or partially recycled back to the upstream membrane (via one or more of FT1, FT10, FT2, FT3, FT4, FT5, FT6, FT7, and FT8). Deionized water is particularly helpful in improving the monovalent / multivalent ion separation efficiency of nanofiltration membranes, as reported elsewhere (Journal of Membrane Science, 2024, 711, 123173; Separation and Purification Technology, 2020, 247, 116965).

[0065] (G) The sequence from (A) to (F) can be repeated multiple times, either as a whole or in one or more subsets, 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 the downstream membrane. For example, in Figure 2 (A), TC18 is routed to RO7; in Figure 2 (B), TC20 is routed to RO8 and TC21 is routed to NF6; and in Figure 3 (C), TC27 is routed to NF7, in order to improve the efficiency of divalent / monovalent ion separation, lithium recovery, and concentration to a higher target ion (e.g., lithium) concentration.

[0066] (H) Furthermore, one or more streams entering one or more nanofiltration or reverse osmosis membranes (e.g., referring to, but not limited to, TC1, TC2, TC4, TC5, TC8, TC9, TC12, TC13, TC16) may be mixed with another stream from the nanofiltration or reverse osmosis membrane outlet, where the outlet is a concentrate outlet or a permeate outlet. In this respect, dashed arrows FT1, FT2, FT3, FT4, FT5, FT6, FT7, FT8, FT9, and FT10 illustrate that fluid from another column or segment may enter. Figure 1 The points of the system described in the text.

[0067] For reference Figure 2AThis paper describes another system suitable for practicing the method described herein. In this system, the method includes the following features: conveying permeate from the RO and NF membranes through a line (TC35) and adding it to a storage tank (PW) for recycling to the desorption medium through a lithium adsorption bed (LA). Alternatively, the line (TC35) may lead to the next reverse osmosis section or another purification step (not shown) before or as an alternative to depositing the permeate in the storage tank (PW). Furthermore, the semi-permeable membrane system includes two nanofiltration units (NF1, NF2) connected in series, and these two NF units are connected in series with two reverse osmosis units (RO7, RO7A), which are in turn connected in series. In other words, Figure 2A The four ultrafiltration membranes depicted are connected in series. A dashed arrow further illustrates the line (TC19), indicating that the permeate from the nanofiltration unit (NF2) can optionally be combined with the lithium-rich eluent (TC1) for reprocessing through the nanofiltration units (NF1 and NF2). Similarly, line (TC34) shows that the permeate from the reverse osmosis unit (RO7A) can be combined with the permeate from the nanofiltration unit (NF2) via line (TC18) for reprocessing through the reverse osmosis units (RO7 and RO7A). Finally, the permeate stream (TC7) from the first nanofiltration membrane (NF1) can be discharged as lean brine or processed through another nanofiltration membrane (not shown). Likewise, the permeate stream (TC33) from the reverse osmosis membrane (RO7) can be connected to another nanofiltration membrane (not shown) for further separation of divalent and monovalent ions; or connected to another reverse osmosis membrane (not shown) to further increase the ion concentration; or connected to the lithium-rich stream for subsequent lithium processing.

[0068] For reference Figure 2BThis paper describes yet another system suitable for practicing the methods described herein. In this system, the method includes the following features: permeate from the RO and NF membranes is delivered through a line (TC38) and added to a storage tank (PW) for recycling to the desorption medium passing through a lithium adsorption bed (LA). Alternatively, the line (TC38) may lead to the next reverse osmosis section or another purification step (not shown) before or as an alternative to depositing the permeate in the storage tank (PW). The lithium-rich eluent reaches the nanofiltration unit (NF1) through a line (TC1). The residual stream (TC7) from the first nanofiltration membrane (NF1) may be discharged as lean brine or processed through another nanofiltration membrane, and the permeate line (TC3) is also the inlet line (TC5) to the reverse osmosis unit (RO2). The permeate line (TC21) of the reverse osmosis unit (RO2) is also the inlet of the nanofiltration unit (NF6), and the permeate line (TC20) of the reverse osmosis unit (RO2) is the inlet line of the reverse osmosis unit (RO8). The permeate line (TC38) is recirculated to the storage tank (PW), and the permeate line (TC37) of the reverse osmosis unit (RO8) is merged with the inlet feed line (TC5) of the reverse osmosis unit (RO2). A portion of the permeate line (TC39) of the nanofiltration unit (NF6) can be processed by another nanofiltration membrane (not shown); another portion (TC39), indicated by the dashed arrow, can be merged with fluid from one or more of the lines (TC1), (TC3), or (TC5). The permeate from the nanofiltration unit (NF6) is connected via a line (TC40); it can be connected to another nanofiltration membrane (not shown) for further separation of divalent and monovalent ions; or connected to another reverse osmosis membrane (not shown) for further increase of ion concentration; or connected to a lithium-rich stream for further lithium processing.

[0069] For reference Figure 2C This describes yet another system suitable for practicing the method described herein. In this system, the method includes the following features: conveying permeate from a reverse osmosis membrane (RO5) through a line (TC30) and adding it to a storage tank (PW) for recycling to the desorption medium passing through a lithium adsorption bed (LA). Alternatively, the permeate line (TC30) may lead to the next reverse osmosis section or another purification step (not shown) before or as an alternative to depositing the permeate in the storage tank (PW). Figure 2CIn this process, lithium-rich eluent is fed to the first reverse osmosis unit (RO1) via line (TC2). The permeate from RO1 is fed to another reverse osmosis unit (RO5) via lines (TC15, TC16), and the residue is fed to the nanofiltration unit (NF4) via lines (TC11, TC12). The residue from the nanofiltration unit (NF4) can be discharged as lean brine via line (TC26) or processed through another nanofiltration membrane (not shown). The permeate from the nanofiltration unit (NF4) can be used as the inlet feed for the nanofiltration unit (NF7) via line (TC27). The residue from the nanofiltration unit (NF7) is routed through line (TC41) to be combined with the inlet feed of the nanofiltration unit (NF4) in lines (TC11, TC12). The lithium-rich permeate from the nanofiltration unit (NF7) is discharged through line (TC42); it can be connected to another nanofiltration membrane (not shown) for further separation of divalent and monovalent ions; or connected to another reverse osmosis membrane (not shown) for further increase of ion concentration; or connected to a lithium-rich stream for further lithium processing. Finally, the residue from the reverse osmosis unit (RO5) is routed through line (TC31) to be combined with the inlet feed of the reverse osmosis unit (RO1) in line (TC2).

[0070] The terms "feed side" and "feed inlet" are synonymous and interchangeable herein. The terms "permeate side" and "permeate outlet" are synonymous and interchangeable herein. The terms "concentrate side" and "concentrate outlet" are synonymous and interchangeable herein.

[0071] Significantly, in the method described herein, most of the lithium ions, water, or both lithium ions and water in the lithium-rich eluent are passed through a nanofiltration membrane at least twice or through two or more nanofiltration membranes to produce a lithium-rich permeate and a lithium-poor and divalent-poor brine.

[0072] Similarly, 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 rate is less than 70%, 60%, 50%, 40%, or less than 30% of the feed inlet volumetric flow rate, and the permeate outlet volumetric flow rate is greater than 30%, 40%, 50%, 60%, or greater than 70% of the feed inlet volumetric flow rate.

[0073] In a preferred embodiment, the nanofiltration membrane comprises one or more piperazine-based membranes. Suitable membranes include several FilmTec™ products, such as 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 comprises one or more aromatic polyamide-based membranes, such as MPD (m-phenylenediamine). Suitable membranes include several FilmTec™ products, such as 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 commercially available from DuPont de Nemours, Inc. (hereinafter “DuPont”) of Wilmington, Delaware. Nanofiltration or reverse osmosis elements can be connected in series or in parallel within a shared pressure vessel, provided that at least two reverse osmosis elements or at least two nanofiltration elements are connected in series, or alternatively, that the lithium-rich eluent passes through a nanofiltration membrane at least twice. In other words, lithium ions preferably pass through at least two nanofiltration membranes, or through a single nanofiltration membrane at least twice. Furthermore, water preferably passes through at least one reverse osmosis membrane, or through a reverse osmosis membrane at least once. The pressure vessel can be connected using standard pipes, valves, fittings, etc.

[0074] The lithium-rich concentrate or brine stream exiting the semi-permeable membrane system contains low levels of impurities and a high concentration of lithium ions. Its temperature is above 40°C, preferably between 60°C and 80°C. The lithium ion concentration of the lithium-rich concentrate stream can be above 5000 ppm (wt lithium), or preferably above 10000 ppm (wt lithium).

[0075] The permeate stream exiting the semipermeable membrane system is the stream that most recently passed through the reverse osmosis membrane, and its temperature is above 40°C, or preferably between 60°C and 80°C. This stream mainly contains water molecules, and based on the concentration of these ions in the lithium-rich eluent, more than 80% of ions, including Ca2+, have been removed. 2+ Mg 2+ Na + Li + SO4 2- and Cl - For divalent ions Ca 2+ Mg 2+ and SO4 2- Also based on the concentration of these ions in the lithium-rich eluent, the ion removal rate is preferably greater than 85%, more preferably greater than 90%.

[0076] For Li + When the permeate is used as at least a portion of the desorption medium, it is preferable to retain dilute lithium ions in the reverse osmosis permeate water to facilitate the desorption process of the lithium adsorbent. The lithium ion concentration in the desorption medium is below 1000 ppm, and preferably between 50 and 500 ppm. In some preferred methods, the reverse osmosis permeate has a lithium ion concentration of below 50 ppm. An appropriate amount of concentrated dissolved lithium solution can then be metered into the reverse osmosis permeate to achieve a suitable lithium concentration to improve or maximize the desorption efficiency of the lithium adsorbent. Furthermore, the reverse osmosis permeate water can be reused for other purposes after deionization, including but not limited to boiler feed, feedstock dissolution, and various processing aids such as liquids for rinsing or cleaning.

[0077] It is well known that the pH of the feed solution can affect the performance of a semipermeable membrane system. Therefore, it may be necessary to adjust the pH of the lithium-rich effluent before processing it through a reverse osmosis / nanofiltration membrane. pH adjustment can be achieved by adjusting the pH before the effluent enters the semipermeable membrane column (e.g., via lines TC1 and TC2, such as...). Figure 1 This is accomplished by metering the addition of an acid or caustic alkali in liquid or solid form to the effluent (as described herein). For nanofiltration membranes used in the methods described herein to separate monovalent and divalent cations, the operating pH range is between pH 1.0 and 6.0, or preferably between 2.0 and 5.0, or more preferably between 2.5 and 4.0. Lower pH is beneficial for increasing the rejection rate of divalent cations and maintaining the permeability of monovalent cations. For reverse osmosis systems, the operating pH range is between pH 1.0 and 14.0 for the removal of common ionic substances. Preferably, if the reverse osmosis membrane is intended to reject boron, the pH will be adjusted to above 8.0, or more preferably above 9.5. Preferably, if the reverse osmosis membrane is intended to reject other ions such as Ca... 2+ Mg 2+ Na + Li + If dissolved silicates, etc., are allowed to pass through the membrane, the pH will be adjusted to less than 8.0, preferably less than 5.0.

[0078] Residual hardness removal

[0079] Residual hardness (including Ca) in lithium-rich concentrate streams or brine after processing through a semi-permeable membrane system 2+ or Mg 2+Lithium-containing streams can be removed at temperatures above 40°C, or preferably between 60°C and 80°C, by chelating ion exchange resins. The lithium-containing stream passes through a fixed or packed bed, in a continuous ion exchange process (e.g., a continuous countercurrent ion exchange (CCIX) unit), or in another suitable design through a resin bed filled with chelating ion exchange resin. In a preferred embodiment, the chelating ion exchange resin is Amberlite™ IRC747, which is commercially available from DuPont. Amberlite™ IRC 747 is a macroporous styrene / divinylbenzene resin bead containing alkylaminophosphonic acid groups.

[0080] Brine Concentration

[0081] The apparatus used in the post-concentration process of brine is not specifically limited, provided that it can operate to evaporate or electrodialyze the solution at high temperatures (e.g., T > 40°C). Suitable apparatus for evaporation, for example, includes one or more devices selected from mechanical vapor recompression (MVR) evaporators, single-effect evaporators, multi-effect evaporators, and flash evaporators. Preferably, evaporation is carried out via an MVR evaporation unit. 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 anode are cation transfer membranes and anion transfer membranes. This forms two concentrate compartments and a central product compartment.

[0082] The stream entering the brine concentration system can have a lithium ion concentration greater than 0.5% (wt lithium), or preferably greater than 1% (wt lithium). The stream leaving the brine concentration system contains a lithium ion concentration greater than 1.5% or 2% (wt lithium), or preferably greater than 2% or 2.5% (wt lithium). The weight percentage of lithium ions is based on the total weight of the respective stream.

[0083] Boron removal

[0084] Boron (e.g., 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-rich concentrate stream after reverse osmosis / nanofiltration to achieve the quality of the final lithium product. Besides using a semi-permeable membrane at a specific pH to trap or pass boron, another method for removing boron from the lithium-rich concentrate stream is to use a boron-selective chelating ion exchange resin at temperatures above 40°C, or preferably between 60°C and 80°C, to reduce the concentration of boron-containing substances. The lithium-containing concentrate stream is passed through a resin bed filled with boron removal ion exchange resin in a fixed bed or packed bed, or in a continuous ion exchange process (e.g., 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 macroporous resin based on a styrene / divinylbenzene copolymer, aminated with N-methylglucosamine.

[0085] precipitation

[0086] In some preferred embodiments, the product of the lithium extraction method described herein is a solid. Preferred solid lithium products include, but are not limited to, lithium salts, such as lithium carbonate. Solid lithium products can be prepared by metering reactants into a lithium-rich permeate solution, preferably at a temperature above 40°C, or more preferably between 60°C and 80°C. Suitable reactants include, but are not limited to, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, other soluble carbonates and bicarbonates, etc. After reaction and precipitation, the solid lithium product can be separated from the supernatant solution by techniques including sedimentation, filtration, centrifugation, etc. The solid lithium product can be washed with deionized water or another washing solution free of impurities that may affect product quality. The washed solid lithium product can be dried in one or more suitable drying devices. The dried solid lithium product can be ground or granulated by conventional means to obtain a suitable particle size range, as required by the application and end-use specifications of the product.

[0087] The following examples are provided to further describe the invention in detail. These examples, which illustrate specific embodiments and preferred modes of carrying out the invention as currently considered, are intended to be illustrative and not limiting. Example

[0088] Example 1 - Lithium Adsorbent Manufacturing

[0089] The lithium adsorbent is synthesized according to the method described in US Patent No. 11371118.

[0090] In short, cover 1 liter of resin with water to bring the total volume to 1200 mL. Add 200 mL of concentrated HCl; stir the mixture and let it stand overnight. Drain the fluid from the mixture using vacuum filtration and rinse the resin repeatedly with water. Mix the resin with 1.5 L of 30 wt% AlCl3 solution and stir. Drain the resin using vacuum filtration. Add 1 L of 30 wt% ammonia solution to the resin and stir, then drain using vacuum filtration and wash with water. Add 1 L of 0.1 N ammonium chloride to the resin and stir, and adjust the pH of the supernatant to 10.5 to 11 with 1 N aqueous NaOH, then wash with water. Add 25 mL of 1 N NaOH and water to give a total volume of 1.6 L. Let the mixture stand for 16 to 24 hours and then wash the resin with water. Then add 2NaAlO2·NaOH in six consecutive batches of 167 g each. Add 36 wt% HCl aqueous solution consecutively. Then wash the resin with water. The resin was washed with 1.5 L of a 26 wt% NaCl aqueous solution and then stored in a reactor. 250 g of LiCl was then added; the mixture was stirred and then placed in an oven at 95°C for 16 hours. At this time, salt(a) was deposited onto the resin. Salt(a) was LiX·2Al(OH)3·nH2O, where X is a halide ion and n is the number of hydrated water molecules, where 0 ≦ n ≦ 10. The number n can be the average of multiple salt(a) molecules. 26 wt% aqueous NaCl was then added to bring the total volume to 2.2 L. The mixture was heated to 70°C and 60 g of solid NH4Cl was added. The resin was titrated with 36% aqueous HCl, followed by titration with 1 N HCl to pH 5, and then separated by filtration to provide the lithium adsorbent used in the following examples.

[0091] Example 2 - Lithium Adsorption and Desorption

[0092] Adsorption: 30 ml of lithium adsorbent was loaded into the column. The Li-containing brine was an aqueous solution containing the following solutes: 1.27 g / L LiCl, 92.58 g / L NaCl, 35.56 g / L MgCl2, 7.55 g / L CaCl2, 3.87 g / L K2SO4, and 2.44 g / L H3BO3. The brine was injected from the top of the column and passed through the column at 6 BV / hr at 40°C. After 30 bed volumes (BV) of brine had passed through the column, the liquid was drained from the column, leaving a 1 cm liquid surface on the top surface of the resin.

[0093] Desorption: The resin was washed at 25°C with 2 BV of DI water at 12 BV / hr. The resin in the column was then heated to 40°C, 50°C, 60°C, 70°C, and 80°C. An aqueous LiCl solution containing 100 ppm lithium by weight was also heated to 40°C, 50°C, 60°C, 70°C, and 80°C. At each column temperature, an aqueous LiCl solution at the same temperature was loaded onto the top of the column and passed through the column at 2 BV / hr for 5 BV. Desorbed samples were collected every 0.2 BV and their lithium content was analyzed.

[0094]

[0095] Example 3 - NF membrane separation of Li / Mg solution

[0096] Commercially available piperazine-based nanofiltration membranes (manufactured by FILMTEC, Edina, Minnesota; available from Nemur DuPont, Wilmington, Delaware (hereinafter “DuPont”)) were rolled into 1812-size elements for performance testing. The 1812 elements featured a 3-coating design. Each flat sheet was cut to a size of 500 mm × 255 mm. After adhesive application, the total active flat sheet area of ​​the entire element was 0.55 m². 2 Mixed salt feed solutions were prepared using 3000 ppm LiCl and 15000 ppm MgCl2 at different temperatures and pH values ​​as shown in the table below. The permeate flow rate was maintained at 190–210 ml / min, which is equivalent to 20–23 L / m³. 2 The permeate flux rate is h. The element recovery rate is 10%, which means that the permeate flow rate in this experiment is 10% of the feed flow rate, simulating the operation of an industrial nanofiltration system.

[0097]

[0098] The Li / Mg separation results are shown in the table below. Both Mg and Li throughput increased with increasing temperature. Mg throughput decreased and Li throughput increased with decreasing pH. Compared to conventional operation (Experiment 1# as a control 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 shown that from Experiment 1# to Experiment 12#, Li throughput increased from 134.2% to 186.2%, while Mg throughput decreased from 33% to 13.1%.

[0099]

[0100] A commercially available nanofiltration membrane, FILMTEC™ LiNE-XD 4040 (manufactured by FILMTEC Corporation, Edina, Minnesota; available from DuPont), was used to separate monovalent and divalent ions. A mixed salt feed solution was prepared with 1800 ppm LiCl and 25000 ppm MgCl2 at different temperature and pH levels as shown in the table below. The permeate flow rate was maintained at 2.6 L / min, corresponding to 20–21 L / m³. 2 • h Permeate flux rate. The element recovery rate is 17%-18%, which means that the permeate flow rate in this experiment is 17%-18% of the feed flow rate, simulating the operation of an industrial nanofiltration system.

[0101]

[0102] The Li / Mg separation results are shown in the table below. Both Mg and Li throughput increased with increasing temperature. Mg throughput decreased and Li throughput increased with decreasing pH. Compared to conventional operation (Experiment 1# as a control 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 indicate that Li throughput remained stable from Experiment 1# to Experiment 12# without significant decrease (between 155% and 154%), while Mg throughput decreased from 2.95% to 1.67%.

[0103]

[0104] Example 4 - Multi-stage nanofiltration (“NF”) separation

[0105] Commercially available piperazine-based nanofiltration membranes (manufactured by FILMTEC, Edena, Minnesota; available from DuPont) were rolled into 1812-size elements for performance testing. The 1812 elements featured a 3-coating design. Each flat sheet was cut to 500 mm × 255 mm dimensions, resulting in an active flat sheet area of ​​0.55 m² for the entire element after adhesive application. 2 A mixed salt feed solution of LiCl and MgCl2 was prepared to simulate the composition of the desorption flow. The permeate flow rate was maintained at 190 to 210 ml / min, which is equivalent to 20 to 23 L / m³. 2 The permeate flux rate is h. The element recovery rate is 10%, which means that the permeate flow rate in this experiment is 10% of the feed flow rate to simulate the operation of an industrial nanofiltration system.

[0106] For the "two-stage nanofiltration (NF) experiment," the permeate composition of the first stage was analyzed and used as the feed composition for the second stage NF. The permeate flux of the second stage NF was 260 ml / min, and the elemental recovery rate was 10%, to simulate the operation of an industrial nanofiltration system.

[0107] In the conventional design at 25°C, the Li / Mg selectivity of the single-stage NF is 30.38. Although the divalent ion rejection decreases at higher temperatures (as shown in Example 3), the two-stage NF design successfully further rejects magnesium ions and allows lithium ions to pass through the NF membrane. The two-stage NF has an even higher Li / Mg selectivity of 174.8 at 55°C, which is higher than the single-stage design at 25°C but lower than the two-stage design at 25°C.

[0108]

[0109] Example 5 - via Amberlite TM IRC747UPS resin removes Mg

[0110] Add 20 ml of Amberlite containing amino-phosphonic acid groups. TM IRC747UPS chelating resin (available from DuPont) was loaded into the column. A solution of 110 ppm Mg was injected from the top of the column. 2+ and 2000 ppm Li + The brine was fed into the column and passed through it at 20 BV / hr at 40°C and 60°C, respectively. The treated solution was collected every 4.5 BV and its Mg content was analyzed. After 120 BV of brine passed through the column, the liquid was drained, leaving a 1 cm liquid surface on the top of the resin. The results are shown in the table below. Mg 2+ The breakthrough point was set at 0.1 ppm. The chelating resin exhibited higher Mg content at 60°C than at 40°C. 2+ Remove workload.

[0111] Table 1. Mg removal at 40°C and 60°C with feeds containing 110 ppm Mg and 2000 ppm Li.

[0112]

[0113] Example 6 - via Amberlite TM IRA743 resin for boron removal

[0114] Add 30 ml of Amberlite containing N-methylglucosamine groups. TMIRA743 chelating resin (available from DuPont) is loaded into the column. A solution with 220 ppm B is injected from the top of the column. 3+ (as boric acid and borates) and 28,000 ppm Li + The feed was passed through the column at 4 BV / hr at 40°C and 60°C, respectively. The treated solution was collected every 2 BV and its B content was analyzed. 3+ Content. After passing 24 BV of brine through the column, the liquid was drained from the column, leaving a 1 cm liquid surface on the top of the resin. The results are shown in Table 2. B 3+ The penetration point was set at 10 ppm. Based on the results obtained, the operating temperature indicates the effect on B. 3+ The removal process had no significant impact on workload.

[0115] Table 2. Mg removal at 40°C and 60°C with feeds containing 220 ppm Mg and 28000 ppm Li.

[0116]

[0117] While certain preferred embodiments of the invention have been described and specifically illustrated above, the invention is not intended to be limited to such embodiments. Rather, it should be understood that although many features and advantages of the invention have been set forth in the foregoing description, along with details of the invention's structure and function, this disclosure is merely illustrative and may be made in detail, particularly in terms of the shape, size, and arrangement of the parts, to the full extent indicated by the broad, general meaning of the terms in the appended claims, within the principles of the invention.

Claims

1. A method for extracting lithium from a dissolved lithium source, the method comprising the following steps: (A) Provide a lithium source containing dissolved lithium ions and one or more impurities; (B) Passing the lithium source through an adsorbent bed containing an adsorbent matrix at a temperature of 40°C or lower to extract lithium from the lithium source onto the adsorbent matrix. (C) Passing the desorption medium through the adsorbent bed at a temperature above 40°C, wherein the desorption medium comprises pure water or a dilute aqueous solution of lithium salt, to obtain a lithium-rich eluent. (D) Adjust the pH of the lithium-rich eluent to below 6.0; (E) The lithium-rich eluent is processed at a temperature above 40°C by a pressurized semi-permeable membrane system comprising at least one nanofiltration membrane and at least one reverse osmosis membrane, wherein a majority of the lithium ions or water in the lithium-rich eluent passes through one nanofiltration membrane at least twice or through two or more nanofiltration membranes to produce a lithium-poor permeate and a lithium-rich and divalent-poor brine. as well as (F) The desorption medium contains at least a portion of the permeate at a temperature above 40°C.

2. The method as described in claim 1, wherein, The impurity contains Na + Ca 2+ Mg 2+ One or more of silicon dioxide and boron.

3. The method as claimed in claim 1 or claim 2, wherein, The adsorbent bed is selected from the group consisting of: fixed bed, packed bed, continuous countercurrent ion exchange (CCIX), continuous ion exchange (CIE), and continuous adsorption / desorption (CAD) devices.

4. The method as described in any one of claims 1, 2, or 3, wherein, The semipermeable membrane system is configured by connecting two or more of the nanofiltration membrane units or reverse osmosis membrane units in series; or the semipermeable membrane system is configured by connecting two or more of the nanofiltration membrane units or reverse osmosis membrane units in parallel.

5. The method as claimed in any of the preceding claims, wherein, The brine was treated with a chelating ion exchange resin bed at a temperature above 40°C to reduce the concentration of divalent cations.

6. The method as claimed in any of the preceding claims, wherein, The brine is passed through a bed of boron-selective ion exchange resin at a temperature above 40°C to reduce the concentration of boron-containing substances.

7. The method as claimed in any of the preceding claims, wherein, The brine is further concentrated at a temperature above 40°C using one or more of a thermal multi-effect evaporator, a mechanical vapor compressor, or electrodialysis.

8. The method as claimed in any of the preceding claims, wherein, One or more lithium salts are precipitated from the brine at temperatures above 40°C.

9. The method of claim 8, wherein, The precipitation is achieved by metering in carbonates to the brine.

10. The method of claim 8 or claim 9, wherein, The precipitation is achieved by metering the addition of carbonate to the brine to obtain precipitated lithium carbonate.

11. The method as described in any of the preceding claims, or the method as described in any of claims 1 to 8, wherein, The lithium salt in the brine is converted into lithium hydroxide by electrodialysis, and the solid lithium hydroxide is separated from the brine by crystallization.

12. The method as claimed in any of the preceding claims, wherein, The adsorbent comprises one or more of aluminum / lithium intercalators, manganese, and titanium.

13. The method as claimed in any of the preceding claims, wherein, The adsorbent further comprises a polymer matrix, and the polymer matrix comprises one or more polymers selected from the group consisting of polystyrene, polyacrylic acid and polyvinyl chloride.

14. The method as claimed in any of the preceding claims, wherein, At least 50% of the lithium in the lithium source is extracted into the adsorbent.

15. The method as claimed in any of the preceding claims, wherein, The desorption medium includes a dilute lithium halide solution.

16. The method as claimed in any of the preceding claims, wherein, The desorption medium has a lithium chloride concentration of less than 1000 ppm and a temperature of more than 40°C.

17. The method as claimed in any of the preceding claims, wherein, The lithium-rich eluent has a lithium concentration in the range of about 200 ppm to about 10,000 ppm.

18. The method as claimed in any of the preceding claims, wherein, The lithium-rich eluent contains divalent cations M2+ in solution, with a dissolved M2+:Li+ weight ratio in the range of about 0.1:1 to 100:1 wt / wt, wherein M2+ includes calcium ions, magnesium cations, or calcium ions and magnesium cations.

19. The method as claimed in any of the preceding claims, wherein, The one or more nanofiltration membranes, the one or more reverse osmosis membranes, or both the one or more nanofiltration membranes and the one or more reverse osmosis membranes comprise polypiperazine or polyamide.

20. The method as claimed in any of the preceding claims, wherein, The semi-permeable membrane system consists of a nanofiltration unit and a reverse osmosis unit, each of which has a feed inlet, a concentrate outlet, and a permeate outlet, wherein the volumetric flow rate of the concentrate outlet is less than 70% of the volumetric flow rate of the feed inlet, and the volumetric flow rate of the permeate outlet is greater than 30% of the volumetric flow rate of the feed inlet.

21. The method as claimed in any of the preceding claims, wherein, The desorption medium is prepared from the permeate stream of the reverse osmosis unit; the permeate stream used to prepare the desorption medium contains dilute lithium halides, wherein the concentration of lithium halides is less than 1000 ppm; and wherein the permeate stream and the desorption medium are prepared at a temperature higher than 40°C.

22. A method for extracting lithium from a dissolved lithium source, the method comprising the steps of: (A) Providing a lithium source, said lithium source comprising dissolved lithium ions or lithium-containing molecules and one or more impurities, such as, but not limited to, Na. + Ca 2+ Mg 2+ Dissolved silicates or boron; (B) Passing the lithium source through a bed of adsorbent, such as an adsorbent containing aluminum / lithium, manganese, or titanium, at the ambient temperature of the lithium source, to extract lithium ions from the lithium source onto the adsorbent. (C) The adsorbent bed is flushed with a desorption medium at a temperature above 40°C, wherein the desorption medium includes pure water or a dilute salt solution, such as a dilute lithium halide solution, to obtain a lithium-rich eluent. (D) Adjust the pH of the lithium-rich eluent to below 6.0; (E) subject the lithium-rich eluent from step (D) to a pressurized semi-permeable membrane system at a temperature above 40°C, wherein the membrane system comprises a nanofiltration membrane and a reverse osmosis membrane to selectively remove divalent ions and increase the lithium concentration of the solute. (F) Optionally, the solute is passed through at least one nanofiltration membrane that retains divalent ions, such as the nanofiltration membrane of step (E), wherein most of the lithium ions and water in the lithium-rich eluent are passed through a nanofiltration membrane at least twice or through two or more nanofiltration membranes. (G) Optionally, the solute is passed through at least one reverse osmosis membrane that retains soluble ions and neutral organic molecules, such as the reverse osmosis membrane of step (E), wherein most water molecules pass through a reverse osmosis membrane at least once or through one or more reverse osmosis membranes. (H) Using the permeate stream generated by the reverse osmosis membrane in the semi-permeable membrane system at a temperature above 40°C as at least a portion of the desorption medium for desorption of the lithium adsorbent bed in step (D).

Images