Liquid-phase lithium extraction

Abstract

It is hereby proposed a liquid-phase lithium extractor, comprising at least one membrane, including a lithium adsorbent material, and a plurality of conduits formed by the at least one membrane and each configured for a liquid flow to pass through the conduit and contact the adsorbent material. Such an extractor forms an improved solution for lithium extraction.

Description

[0001] LIQUID-PHASE LITHIUM EXTRACTION

[0002] TECHNICAL FIELD

[0003] The disclosure relates to a liquid-phase extractor. The disclosure also relates to a method for extracting lithium from a liquid flow, using the extractor.

[0004] BACKGROUND

[0005] Adsorptive extraction is a technique that involves separation of a component from a multi-component liquid mixture through the adsorption of the component onto an adsorbent material. For such adsorptive extraction, packed bed columns have been widely used. Such a column is usually packed with a solid adsorbent material which has a high affinity for the target component in the mixture.

[0006] Exemplary applications can include separation of a metal, such as lithium, calcium or sodium, from a multi-component liquid mixture, such as produced water from an oil or gas field, geothermal water, deep groundwater or seawater.

[0007] For example, document WO 2019 / 000095 Al discloses a method of recovering lithium from energy process water, using a reactor column containing a titanium oxide molecular sieve that adsorbs lithium ions.

[0008] However, such packed bed columns present certain challenges that affect the efficiency of the separation of the target component. One such challenge is a pressure drop in the column caused by the resistance to flow due to the presence of the packing material. Other challenges include a limited contact surface between the media (packing material) and the feed comprising the target component, and the fluidization of the media (in a bed form) in the column.

[0009] Within this context, there is a need for improved solutions notably for adsorptive separation, particularly of lithium.

[0010] SUMMARY

[0011] It is therefore provided a liquid-phase lithium extractor, comprising at least one membrane including a lithium adsorbent material, and a plurality of conduits formed by the at least one membrane and each configured for a liquid flow to pass through the conduit and contact the adsorbent material.

[0012] The extractor may comprise any one or more of the following: the lithium adsorbent material comprises an ion exchange adsorbent; the ion exchange adsorbent comprises a metal oxide, preferably selected from titanium oxide, manganese oxide, and aluminium oxide hydroxide; the at least one membrane comprises at least one of carbon fibers, glass fibers, metal, and a polymer; the at least one membrane comprises a support layer coated with the adsorbent material, the support layer being made of at least one of carbon fibers, glass fibers, metal, and a polymer; the at least one membrane comprises a binding material fixing the adsorbent material; the ratio of the conduit length to the conduit height is 100 to 10,000; and the ratio of the conduit width to the conduit height is 50 to 10,000; the permeability of the extractor is from 1,000 to 40,000 Darcy under laminar flow conditions; the at least one membrane comprises a stack of membrane layers; the stack of membrane layers consists of a stack of planar and / or parallel membrane layers; the plurality of conduits comprises a respective conduit between each pair of adjacent membrane layers; the extractor further comprises a plurality of separators, each fixed to the at least one membrane; the distance between two adjacent separators is in the range of 10 to 90 times the conduit height; the separator occupancy of the at least one membrane ranges from 1 % to 20% with respect to the total surface area of the membrane; the flow resistance of the extractor caused by the separators is equal to or less than 20% with respect to the total flow resistance of the extractor; the separators vary in size and / or shape; each of the separators has an elongated shape having an aspect ratio of 2 to 6; the at least one membrane comprises a stack of membrane layers, and the separators of one membrane layer of the stack are aligned with the separators of another membrane layer of the stack by at least 10%; the at least one membrane comprises a plurality of separator occupancies; the separator occupancy at one section of the at least one membrane can be 20% to 200% greater than the separator occupancy of a different section of the membrane; the extractor comprises at least 10 membranes; the conduit height distribution has a coefficient of variance in the range of from 1 % to 15%; and / or the extractor further comprises at least two different conduit heights, wherein the difference in the conduit height is in the range of from 10% to 70%.

[0013] It is further provided a method for extracting lithium from a liquid flow, comprising providing the above-described extractor; passing the liquid flow into the extractor; recovering a flow depleted in lithium from the extractor; passing a desorbing solution into the extractor; and recovering a stream enriched in lithium from the extractor.

[0014] The method may comprise one or more of the following: the method further comprises orienting the extractor horizontally; the lithium adsorbent material comprises an ion exchange adsorbent; the ion exchange adsorbent comprises a metal oxide, preferably selected from titanium oxide, manganese oxide, and aluminium oxide hydroxide; the desorbing solution is an acidic solution; and / or the method further comprises rinsing the extractor with water.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Non-limiting examples will now be described in reference to the accompanying drawings, where:

[0017] Fig. 1 illustrates a perspective view of an example of the liquid-phase extractor; Fig. 2 illustrates a side view of an example of the liquid-phase extractor;

[0018] Fig. 3a and Fig. 3b illustrate a top view of a membrane and separators of an example of liquid-phase extractor;

[0019] Fig. 4 illustrates a side view of a stack of membranes of an example of the liquid-phase extractor; and

[0020] Fig. 5 illustrates an example of the liquid-phase extractor; and Fig. 6 shows a flowchart of one example of the method.

[0021] DETAILED DESCRIPTION

[0022] Liquid-phase lithium extractor

[0023] It is hereby proposed a liquid-phase lithium extractor comprising at least one membrane including a lithium adsorbent material.

[0024] The extractor further comprises a plurality of conduits formed by the at least one membrane and each configured for a liquid flow to pass through the conduit and contact the adsorbent material.

[0025] Such a liquid-phase extractor forms an improved solution for separating lithium from a liquid flow (i.e., feed) because the extractor avoids or at least reduces the pressure drop, which has been a problem of the conventional packed bed column. The extractor further provides reduced media loss and a larger contact surface area (surface area for the contact between the liquid flow and the adsorbent material) than the packing material (for example, packed pellets) of the conventional packed bed column, at least for a given quantity of adsorbing material. Concerns about fluidization of the media (e.g., problems such as controlling the fluid-like behavior of the media) are also mitigated.

[0026] The lithium adsorbent material may be any adsorbent configured to adsorb lithium.

[0027] The terms "sorbent", "adsorbent" and "absorbent" may be used interchangeably herein.

[0028] For example, the lithium adsorbent material may comprise at least one of an ion exchange adsorbent, metal-based sorbent (e.g., Al-based, Mn-based and Ti- based), Li-AI layered double hydroxide (LiAI-LDH), antimonate lithium, organic hybrid lithium adsorbents, crown ether, inorganic adsorbents such as such as poly(glycidyl methacrylate (PGMA), hydrogel, polymer polysulfone (PSF)-graft-4'-aminobenzo-15- crown-5-ether (PSF-g-AB15C5), activated carbon, graphite, carbon molecular sieve, activated alumina, clay, silicotitanate, zeolite, ion exchanged zeolite, hydrophilic zeolite, hydrophobic zeolite, modified zeolite, natural zeolites, unipolar resin, bipolar resin, methacrylic ester copolymer, carbon fibers, nano-materials, metal salt adsorbent, silica, alkaline resins, metal organic framework (MOF), UiO-66, HKUST-1 and ZIF-8, a doped activated carbon, a doped graphene, an alkali-doped inorganic adsorbent and a composite adsorbent thereof.

[0029] As an example, the lithium adsorbent material may be an ion exchange adsorbent.

[0030] The ion exchange adsorbent may comprise a metal oxide.

[0031] The metal oxide may be selected from titanium oxide, manganese oxide, and aluminum oxide hydroxide.

[0032] More specifically, the lithium adsorbent material may be lithium titanium oxide, lithium manganese oxide, or LiCI / AI(O H)s.

[0033] The use of such metal oxides as an adsorbent material allows for a higher adsorption capacity, better selectivity, higher stability of the material during the lithium recovery process and an ecofriendly property compared to other lithium extraction technology (such as DLE (Direct Lithium Extraction) process).

[0034] The extractor may further comprise an entry at one end of the membrane(s) along the direction of the liquid flow (i.e., one end of the membrane(s) where the liquid flow enters) and an exit at the other end of the membrane(s) along the direction of the liquid flow (i.e., the other end of the membrane(s) where the liquid flow exits). The "entry" and "exit" as used herein do not limit the orientation or direction of the liquid flow. Indeed, the extractor may be used either way (i.e., the roles of entry and exit can be interchanged), allowing the liquid flow to pass through the extractor in two directions.

[0035] The membranes may each optionally comprise one or more additional adsorbent materials, for example one or more other metal (non-lithium) adsorbent materials, such as a magnesium adsorbent material and / or an iron adsorbent material.

[0036] The extractor comprises a plurality of conduits (or passages / channels for liquid flow).

[0037] The conduits may each be straight, with a constant and uniform cross-sectional area (in other words, there is inside each conduit no change of direction, for example, without any curves, bends, or obstacles). Such a conduit configuration provides reduced resistance (thus reduced pressure drop), consistent performance, and ease of installation. The at least one membrane may optionally comprises a stack of membrane layers (i.e., a piling of membrane layers, which will be explained in detail below). In such a case, the plurality of conduits may comprise a respective conduit between each pair of adjacent membrane layers. In other words, each conduit (or passage) is formed between two adjacent membranes, as the spacing, gap or passage left for liquid flow between the two adjacent membranes. Optionally, each "two adjacent membranes" (i.e., each pair of adjacent membranes) may form therebetween a respective conduit.

[0038] Each conduit of the extractor may be defined by a conduit length, a conduit height, and a conduit width.

[0039] The conduit length as used herein refers to the dimension of the conduit which is parallel to the direction of the liquid flow. In other words, the conduit length corresponds to the distance between the entry of the extractor and the exit of the extractor. The conduit height as used herein refers to the dimension of the conduit between two surfaces of the membrane(s). When the extractor comprises two membranes or two membrane layers, the conduit height refers to the length between the two membranes (between the surface of one membrane and the surface of another membrane) or two membrane layers (between the surface of one membrane layer and the surface of another membrane layer). When the extractor comprises a tubular membrane (which will be explained below), the conduit height refers to the length between two opposite surfaces of the membrane (for example, diameter). The conduit width as used herein refers to the dimension of the conduit in a direction perpendicular to the direction of the conduit length and to the direction of the conduit height.

[0040] The ratio of the conduit length to the conduit height and / or the ratio of the conduit width to the conduit height may be determined to optimize the contact time and the surface are between the feed and the extractor while minimizing the pressure drop between the entry and the exit of the extractor. Such ratio(s) may be determined based on the type of liquid to flow in the extractor.

[0041] The extractor may have a ratio of the conduit length to the conduit height of between 100 and 15,000, for example, between 100 and 5,000, between 5,000 and 10,000, and between 10,000 and 15,000.

[0042] Additionally, the extractor may have a ratio of the conduit width to the conduit height of between 50 and 10,000, for example, between 50 and 1,000, between 1,000 and 5,000, and between 5,000 and 10,000.

[0043] The extractor comprises at least one membrane.

[0044] By "membrane" is meant a thin layer of material, which is thinner, for example, at least ten times thinner, than its other two dimensions (length and width).

[0045] The (e.g., each) membrane may be in a flexible material. The (e.g., each) membrane may be put under tension in the extractor.

[0046] The (e.g., each) membrane may have a tensile strength of greaterthan 1 N / mm, for example, 2 N / mm or more, and 4 N / mm or more.

[0047] The (e.g., each) membrane may have a thickness of 1 mm or less. Specifically, the thickness may range from 0.1 to 1 mm, such as 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm.

[0048] The (e.g., each) membrane may have a planar, rectangular and / or tubular shape.

[0049] The at least one (e.g., each) membrane may comprise a stack of membrane layers.

[0050] By "the stack of membrane layers" is meant a configuration in which a plurality of membranes or portions of membranes are layered or piled on top of another to form a composite structure. For example, a single membrane may be arranged, for example via folding, to form a stack of individual portions (layers) within the membrane, thereby forming a stack of membrane layers and a plurality of conduits between each pair of adjacent membrane layers. Alternatively or additionally, the extractor may comprise membranes (in other words, layers of membranes), forming a stack of membrane layers. Thus, the term "membrane layer" may encompass an individual membrane and a portion of an individual membrane.

[0051] The stack of membrane layers may comprise identical membrane layers within the stack, or may comprise different membrane layers (for example, membrane layers having variations in thickness, spacing, material composition, etc.).

[0052] When membranes form a stack, the membranes may optionally be planar and / or rectangular, and all be parallel one to the other.

[0053] The stack of membrane layers may consist of a stack of planar and / or parallel membrane layers. In such a case, the conduits are also layered and parallel one to the other.

[0054] The configuration of the stack of planar and parallel membrane layers with each other provides reduced resistance (thus reduced pressure drop), consistent performance, and ease of installation. Furthermore, such a structure provides a simplified assembly and ease of installation, thus simplifying the manufacturing process.

[0055] Below, the term 'membrane' may refer to a membrane layer, i.e. an individual and integrally formed piece of membrane material or alternatively a portion of a larger piece of membrane material forming a membrane layer.

[0056] The membranes (e.g., membrane layers) may be stacked (i.e., piled up) in a uniform and / or periodic pattern. By "uniform pattern" is meant that the membranes are positioned with a consistent orientation and a consistent spacing (i.e., consistent conduit height) between each other. This means that each membrane is aligned in the same direction (e.g., in parallel with each other), in which the conduit height between adjacent membranes remains the same throughout the stack. Such a uniform pattern facilitates the control of the flow distribution of the liquid. By "periodic pattern" is meant that a distinct arrangement of the membrane stacking pattern repeats at regular intervals. Such an arrangement allows the conduit height to be substantially constant. The conduit height distribution has a coefficient of variance in the range of from 1 % to 15%. This distribution affects how the liquid flow is distributed within the stack and the overall saturation level of the adsorbent material at the end of the adsorption process. This is particularly well-adapted for applications that demand high recovery rates. The extractor, optionally having such an arrangement, may be used in an application achieving capture efficiency greater than 90%.

[0057] When the membrane has a tubular shape, each tubular membrane may be also stacked (i.e., piled up), forming a stack of membrane layers. Such a configuration allows for efficient space utilization and increased contact surface between the liquid flow and the adsorbent material. The tubular membrane may be stacked so as to form a row. The row of the tubular membrane may be further stacked so as to form an array, comprising rows and columns of membrane. Within the stack of membrane layers, each tubular membrane may be all identical or different (varying, for example, in the conduit height and / or the membrane material).

[0058] All conduits of the extractor may present the same (thus unique / constant) conduit height. Alternatively, the extractor may comprise at least two different conduit heights. The difference in the conduit heights may be in the range of from 10% to 70%. In this case, the different conduit heights may be alternated.

[0059] Such a periodic and alternate stacking of membrane layers having, for example, two different heights can reduce the overall void fraction (empty space) of the extractor while preserving permeability or increase permeability at a constant void fraction.

[0060] Each conduit height of the extractor may retain 96% or greater of its height under a load of 5 kPa applied perpendicularly to the extractor.

[0061] For example, the conduit height can be in the range from of 0.1 mm to 2.0 mm; for example, 0.5 mm, 1 mm, 1.5 mm.

[0062] The conduit length can be in the range of from 50 mm to 2000 mm.

[0063] The ratio of the conduit volume to the total volume of the extractor (membrane layers) may be in the range of from 15% to 70%. The ratio of the surface area of each membrane (two sides of each membrane) to its volume can be in the range of from 1000 m2 / m3to 8000 m2 / m3.

[0064] The membrane(s) may each comprise at least one of carbon fibers, glass fibers, metal, and a polymer. The carbon fibers may be reinforced fibers (a composite material made of carbon fibers embedded in a polymer matrix). The carbon fibers may be woven or non-woven fibers. The glass fibers may be reinforced fibers (a composite material made of glass fibers embedded in a polymer matrix). The glass fibers may be woven or non-woven fibers. The metal may be for example aluminum or steel, in the form of wire mesh or a foil). The polymer may be for example, polyvinylidene fluoride (PVDF), graphene oxide / polyvinylidene fluoride (GO / PVDF), polyethersulfone (PES), polyvinylidene fluoride-polydopamine (PVDF-PDA), polydimethylsiloxane-polydopamine (PDMS-PDA), polyether sulfone membrane (PM), composite polymeric membrane, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), (sulfonated reduced) GO, vermiculite,

[0065] For example, the membrane may each comprise PVDF. The use of PVDF allows for a better stability and rigidity of the extractor.

[0066] Each membrane may comprise a support layer coated with the adsorbent material, the support layer being made of at least one of carbon fibers, glass fibers, metal, and a polymer. The carbon fibers, glass fibers, metal and the polymer are as defined above. The support layer is a layer that thus carries the adsorbent material, by way of being coated with said adsorbent material.

[0067] The support layer may be coated with the adsorbent material according to a conventional coating process known in the field, for example, dip-coating, spraying, impregnation, surface grafting, solvent evaporation, electrodeposition, in situ polymerization, electrochemical polymerization, post-polymerization, click chemistry, electrospray deposition, chemical vapor deposition . A suitable coating process may be selected depending on the type of the adsorbent material and / or of each membrane. As an example, the support layer may be treated on its surface by, for example, chemical treatment, plasma treatment, or physical deposition techniques, to introduce reactive groups or functional moieties, and then the adsorbent material may be grafted on the modified surface. As another example, the (e.g., each) membrane may be impregnated with an adsorbent material suspended in a liquid or a slurry of the adsorbent material. Excessive liquid or slurry may be removed by known methods and the impregnated membrane is dried using conventional means.

[0068] The extractor may comprise three membranes forming two conduits. Alternatively, the extractor may comprise five membranes forming four conduits.

[0069] The extractor may comprise at least 10 membranes.

[0070] The extractor may comprise several stacks of the membrane layers. For example, several stacks can be stacked on top of one another to create an assembly of different shapes. In such an assembly, it is not necessary to precisely control the positioning of separators (which will be explained more in detail below) between the stacks because any irregularities or variations in the alignment of the separators between the stacks only affect a small portion of the conduits within the complete assembly.

[0071] The membrane(s) may further each comprise a binding material fixing the adsorbent material onto / into the remainder of the membrane(s) (for example, the support layer of each membrane). The binding material may be a polymer or adhesive material that is compatible with both the adsorbent material and the remainder of the membrane(s) (for example, the support layer of each membrane). For example, the binding material may be at least one of a methacrylate polymer, a crown ether, organophosphate, an organic carboxylic acid, a beta diketone, a calixarene derivative, a cyclodextrin, acrylic acid, methacrylic acid, methyl methacrylate, acrylamide, 2- vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, tetraethoxysilane, a self-synthetic monomer such as ethylenediamine-tetra- / V-3-pyrrole-lyl) propylacetamide, tymine- 3-isocyanatopropyl-triethoxysilane, and 2,4-dioxopenthan-3-yl-methacrylate, orthoboric acid.

[0072] The use of the methacrylate polymer as a binding material with each membrane comprising PVDF and including a metal oxide adsorbent material allows for better fixation of the adsorbent material due to the good compatibility between the binding material and the membrane. The extractor may further comprise a support, to which the membrane(s) is / are adhered, for example, using an adhesive or by way of interlocking design, or mechanical fastening.

[0073] The support may be a casing, a frame, or one or more rods.

[0074] A casing as used herein refers to a structure that serves as a physical boundary to contain the membrane(s), such as a box, a bin, a housing, or a container. Any suitable casing may be selected as long as it comprises two openings (for example, forming the entry and the exit of the extractor, as defined above) that allow the liquid flow to pass through the extractor. The size of the openings of the casing may be adjusted to cover (span and encompass) the entire height and width of the extractor, thereby allowing forthe unrestricted flow and uniform entry of liquid throughout the entire extractor. A frame may comprise a rigid material like metal (e.g., stainless steel) or polymer. As another example, the membrane(s) each may be adhered to rods comprising a rigid material like metal (e.g., stainless steel) or polymer.

[0075] Alternatively or additionally, the membrane(s) may each be put under tension (i.e., stretched or subjected to a pulling force to create a state of tension in the membrane(s)). The extractor may further comprise a structure arranged and configured for applying and / or maintaining such tension to the membrane(s) in a direction parallel to the direction of the liquid flow. For example, the extractor may comprise clamps and / or tensioning devices holding the membrane(s) under tension. Such a configuration facilitates further the maintenance of spacing for the conduit height while increasing the rigidity and the stability of the extractor.

[0076] Alternatively or additionally, the extractor may further comprise one or more separators between membranes (or membrane layers), each respective separator being fixed to each membrane.

[0077] The respective separator may be fixed to one surface (e.g., one side) of each membrane or two surfaces (i.e., two surfaces of each membrane).

[0078] The presence of separators facilitates further the maintenance of spacing for the conduit height while increasing the rigidity and the stability of the extractor.

[0079] The respective separator may be fixed to each membrane by, for example, adhesive bonding. Alternatively, one or more respective separators may be printed on each membrane, for example using a stencil and separator ink, which can be cured through thermal or UV treatment.

[0080] The distance between two adjacent separators (the distance between each of the separators) may be in the range of 10 to 90 times the conduit height. The distance between two adjacent separators refers to the distance between the geometric center of a separator to the geometric center of another separator in a direction parallel to the plane of the membrane(s).

[0081] For example, the distance between two adjacent separators may be at least 10 mm, for example, about 10, 15, 18, or 20 mm.

[0082] In respective conduit, one or more separators may occupy up to 8% of the volume of the conduit. In other words, with respective to the total volume of the conduit, at least 92% of the volume of the conduit may be unblocked and available (free) for the flow of the liquid flow through the conduit.

[0083] The separators may be present (e.g., adhered or printed) on at least a portion of one surface of each membrane. The separator occupancy of each membrane may range from 1% to 20% with respect to the total surface area of each membrane. The separator occupancy as used herein refers to an area of the surface of a membrane occupied by the separators, with respect to the total surface area of the membrane.

[0084] The distribution of separators on each membrane can be uniform throughout the same membrane or varied in different sections of the membrane.

[0085] The homogenous distribution of separators over the entire membrane allows for a better stability of the extractor and a uniform flow of the liquid flow.

[0086] Each membrane may comprise a plurality of separator occupancies, i.e., the separator occupancy may differ among the sections of the membrane.

[0087] The separator occupancy at one section of one membrane may be 20% to 200% greater than the separator occupancy of a different section of the membrane. For example, the separator occupancy near the entry, the exit, and the sides of the extractor of the membrane may be 20% to 200% higher compared to the separator occupancy in the center of the extractor.

[0088] The separators may be substantially aligned between different membranes (e.g., different membrane layers) (i.e., the separators of one membrane (layer) may be positioned in a way that they overlap or are in close proximity to the separators of another membrane (layer)) along the direction of the conduit height. This alignment ensures that, when a mechanical load is applied perpendicularly to the membranes, the extractor may transfer the load evenly throughout the entire membranes. In addition, such an alignment may avoid or at least reduce the risk of partial collapse of the conduits under pressure.

[0089] The separators of different membranes may be aligned by at least 10%. In other words, the separators of one membrane may be aligned with the separators of another membrane by at least 10%, for example, 30%, 50%, 70%, 90% or 100%.

[0090] When the separators of different membranes are aligned vertically, the vertical alignment of the membranes may be indicated by a vertical column of separators that can be seen from the edge of the membranes.

[0091] The separators may be distinct solid objects at the millimeter scale.

[0092] The separators may vary in size and / or shape for controlling the spacing of respective conduits between the membranes (e.g., membrane layers) and providing resistance against compressive loads applied to the extractor.

[0093] For example, the extractor may comprise a first separator having a first size and a first shape, and a second separator having a second size and a second shape, and the first size and / or the first shape differ from the second size and the second shape, respectively.

[0094] The first size may be smaller than the second size.

[0095] Smaller separators of one membrane (e.g., one membrane layer) do not need to be precisely aligned from one membrane to another membrane (e.g., another membrane layer), as long as larger separators, which bearthe compressive load, have a significant overlap (i.e., are aligned by, for example, 50%, 70%, 90% or 100%) among different membranes (e.g., membrane layers).

[0096] The separators may each have any suitable shape, for example, cylindrical, rectangular, square, or elongated or oblong shape.

[0097] As another example, the separators may have an oblong or elongated shape having an aspect ratio of 2 to 6. The aspect ratio herein is defined as the ratio of its long axis to the width axis, which is perpendicular to the long axis. The separators may each comprise a polymer (such as polypropylene or polyethylene), metal (such as stainless steel or aluminum), silica-filled polymer, ceramic, glass, or silica. As an example, the separators may each comprise a silica- filled epoxy resin that is thermally cured.

[0098] The separators may be periodically arranged. By "periodically" is meant that the separators are arranged in a regular and repetitive pattern on the (e.g., each) membrane. The separators may be placed at fixed intervals (in other words, the distance between two adjacent separators is identical throughout).

[0099] For example, the separators may be arranged in a regular grid pattern, in staggered rows (where the separators in one row are offset from the separators in the adjacent rows), or in an alternating pattern (such as a checkerboard or zigzag pattern).

[0100] Alternatively, the separators may be arranged in a random pattern.

[0101] The separators may be arranged in different patterns on a membrane (e.g., each membrane) . For example, the (e.g., each) membrane may comprise separators fixed in a random pattern in one section of the membrane, and separators fixed periodically in another section of the membrane.

[0102] Each separator may further comprise a bonding material applied to the top and / or the bottom surface of the separator. This can further improve the overall mechanical stiffness of the membrane(s) and make the extractor more resistant to deformation in any direction. For example, the bonding material may be applied to more than 20% of the separators.

[0103] The extractor may comprise at least one of the support (such as a casing, a frame or a rod), the structure arranged and configured for applying and / maintaining tension to the membrane(s) (such as a clamp or a tensioning device) and separators. When the extractor comprises two or three of them in combination, this allows a better control of the mechanical stiffness of the extractor based on the stress applied in different sections of the membrane. The edges of the extractor (i.e., sections around the entry, the exit and the sides of the extractor) can be more prone to crack as a result of uneven liquid velocity distributions than the center of the extractor. Thus, for example, when the membrane(s) is / are adhered to a frame along its perimeter, or when the membrane(s) is / are hold under tension, the edges of each membrane are more resistant against cracks.

[0104] The extractor may further comprises a connector (pipe or tube, for example) for its connection to a different system, such as a reactor.

[0105] The extractor is explained above to accommodate a configuration of the longitudinal flow (in other words, the direction of the liquid fluid goes along the length the extractor, i.e., along the direction of the conduit length).

[0106] Mechanical properties of the extractor

[0107] The permeability of the extractor may be in the range of from 1,000 to 40,000 Darcy under laminar flow conditions, as measured by the following formula:

[0108] B = pQL / AAp

[0109] In the formula, p corresponds to a function of viscosity (dynamic viscosity) of the liquid flow, Q. corresponds to the volumetric liquid flow rate through the extractor, L corresponds to the length of the flow path, A corresponds to the area of the flow, and Ap corresponds to the pressure drop.

[0110] The laminar flow refers to the smooth and orderly movement of fluid particles in parallel layers or streamlines, with little to no mixing or turbulence between the layers.

[0111] When the permeability is modified to higher than 1 Darcy, the permeability of extractor may be fixed higher than 0,003*10-7cm2 / s.

[0112] The flow resistance may be fixed higher than 100 LMH (liters per square meter per hour).

[0113] The permselectivity factor ( ) of the extractor may be measured by the following formula :

[0114] P = PK / Ca / Mg / Pu-

[0115] In the formula, P refers to the permeability coefficient (cm2s-1), and can be calculated as follows:

[0116] P = Jid / (CFi- Ri), in which i = Li+, K+, Ca2+, Mg2+.

[0117] In the formula, d (cm) corresponds to the effective membrane thickness; and (CH-CRi) corresponds to the concentration difference (mg / L) between the feeding solution (feed at the entry) and the receiving solution (feed at the exit), and J refers to the permeation flux (mg / cm2 / h), which can be calculated as follows:

[0118] Ji = ACjV / At where V (mL) and A (cm2) are the volume of the receiving solution and the effective membrane area, respectively, and Aci / At is the change of the concentration in the receiving solution.

[0119] The permselectivity factor PK / U, Pca / u, PMg / u of more than 1 indicates that the membrane has higher permeability for K, Ca or Mg ions compared to Li ions while the permselectivity factor PK / U, Pca / u, Mg / u of less than 1 indicates a lower permeability for K, Ca or Mg ions compared to Li ions. The permselectivity may be appropriately adjusted depending on the configuration of the extractor (for example, longitudinal flow or tangential flow).

[0120] The Reynolds number of the extractor may be 1,000 or less or have a Reynolds numbers below 1,000, as calculated by the following formula :

[0121] Rep= pVsDp / (p(l-e))

[0122] In the formula, p corresponds to the liquid density, Vscorresponds to the superficial velocity, Dpcorresponds to the equivalent diameter, p corresponds to a function of viscosity (dynamic viscosity) of the liquid flow, and e corresponds to the void fraction.

[0123] The height of each separator may be chosen to achieve the desired kinetics for adsorption and ensure high permeability within the specified range. For example, when the separators have a smaller contact area with the liquid flow, the flow resistance of the extractor caused by the separators is equal to or less than 20%, for example less than 10%, with respect to the total flow resistance of the extractor.

[0124] The extractor is further discussed below by way of examples referring to the Figures.

[0125] Fig. 1 illustrates an example of the extractor 1, comprising a stack of membranes 2 (corresponding to a stack of membrane layers) including a lithium adsorbent material 3 and respective conduits 5 between each pair of adjacent membranes.

[0126] The extractor 1 may comprise a casing 6 to which the membranes 2 are adhered

[0127] (in Fig. 1, the stack of the membranes 2 in the casing is visible for clear view). The casing 6 may comprise four walls (two side lateral walls 61 and a top wall 60 and bottom wall 62) and two openings for the entry and exit of the liquid flow (longitudinal flow which is represented by two solid arrows 7). Each membrane 2 may be adhered to the two side lateral walls 61 of the casing 6.

[0128] Fig. 1 illustrates an example of a casing, but it is understood that, in a variant, the membranes may alternatively be adhered to a frame or a rod. For example, membranes are adhered to, along its perimeter, a frame comprising a rigid material like metal (e.g., stainless steel) or polymer. As another example, the membranes may be adhered to rods. For example, in the case of rectangular membranes, the membranes may be adhered to four rods at their four corners.

[0129] Fig. 1 also illustrates separators 4, but it is understood that Fig. 1 is a simple example, and it is possible that the separators are not present in a variant, and their function of holding the stack together and ensuring the presence of the conduits (i.e., passages) may be replaced by alternative structures, such as a support (e.g., casing, frame or rod) or a structure arranged and configured for applying and / maintaining tension to the membranes.

[0130] As shown in Fig. 1, separators 4 may have a cylindrical shapes, and arranged periodically on each membrane 2 such that the separators 4 are aligned vertically on top of one another with the membrane 2 in between. When the separators of different membranes are aligned vertically, the vertical alignment of the membranes may be indicated by a vertical column of the separators that can be seen from the side of the stack, as shown in in Fig. 2.

[0131] Fig. 2 illustrates the membranes 2 of the example, where the figure shows that each membrane 2 comprises a support layer 2' coated with the adsorbent material 3, thus carrying the adsorbent material 3. In Fig. 2, the separators 4 are fixed on each membrane 2 (in other words, the support layer 2' is coated with the adsorbent material 3, forming a membrane 2, and then the separators are disposed (by printing or adhesion) on the membrane 2. In a variant, the separators 4 may be fixed in each membrane 2, in other words, the separators 4 are first disposed (by printing or adhesion) on the support layer 2', and then the support layer 2' is coated with the adsorbent material 3 to form a membrane 2. Fig. 3a illustrates a variant in which the extractor comprises elongated separators. The separators 40 may be oriented in a different direction on the same membrane 20 (the separators are not aligned along the same axis). For example, as shown in Fig. 3a, each separator is oriented orthogonally to each other. The separators with different orientations may be arranged (e.g., adhered or printed) in a periodic pattern, which allows for the construction of the stack with a single pattern.

[0132] As another example, the extractor may comprise one or more first membranes having elongated separators, and one or more second membranes having elongated separators, where the first membranes and the second membranes are adjacent to each other. The separators of the first membranes may be arranged periodically and oriented orthogonally to each other, as shown in Fig. 3a. The separators of the second membranes may be arranged periodically and oriented orthogonally to each other, as shown in Fig. 3a. Fig. 3b illustrates that the position of the separators 40 of the first membrane may partially overlap (partially coincides or aligns) with the position of the separators 40' of the second membrane (for clear view, Fig. 3b does not illustrate the second membrane, which is present between the separators 40 and the separators 40'). Such an arrangement can minimize or at least reduce the likelihood of the membranes shifting in relation to each other, by creating an interlocking feature when pressure is applied to the stack in a direction perpendicularto the plane of the membranes.

[0133] Referring back to Fig. 1, the membranes 2 are stacked (i.e., piled up) in a uniform pattern, thus in parallel with each other, forming a constant conduit height in the stack.

[0134] In another variant, as shown in Fig. 4, the conduits or passages of the extractor may comprise two conduits 5 and 5' of different conduit heights. The different conduit heights may be alternated in a regular pattern. For example, as shown in Fig. 4, three adjacent membranes 2 separated by a smaller conduit height 5 can be defined as a group of membranes 20, 21, and two groups 20 and 21 of the adjacent membranes 2 can be separated by a conduit 5' of larger height. This pattern of stacking (i.e., two groups 20 and 21 of the adjacent membranes 2 separated by a conduit 5' of larger height) may be repeated, thereby forming a periodic pattern. In such a configuration, the conduits having a larger conduit height can handle a larger portion of the liquid flow (for example, carrying 2 to 50 times more liquid flow compared to the conduits having a smaller conduit height), and the conduits having a smaller conduit height can enhance the uniform distribution of the adsorbent material and improve the adsorption and desorption kinetics.

[0135] Fig. 5 illustrates a variant of the extractor with numeral reference 101 in which the membranes 102 have a tubular shape (the membranes are each rolled around a central axis). The conduits 105 are formed as the cylindrical space inside each tubular membrane 102. Although only one row of membranes 102 is shown on the figure, the extractor 101 may optionally comprise several rows stacked one on another. In such a case, conduits may also be formed as the spacing between different membranes.

[0136] Method for extracting lithium from a liquid flow

[0137] The extractor as presented above may be used in a method for extracting lithium from a liquid flow (feed).

[0138] Referring to Fig. 6, the method comprises providing S10 an extractor as defined above.

[0139] The method may further comprise orienting S20 the extractor horizontally. By "horizontally" is meant that orientation of the extractor (along the direction of the liquid flow) is perpendicular to the gravity axis. Such a horizontal orientation can minimize or at least reduce the charge loss, which has been a problem of the conventional packed bed column due to its vertical orientation of the column.

[0140] The method then comprises passing S30 the liquid flow into the extractor.

[0141] The method may further comprise bringing the liquid flow in contact with the lithium adsorbent material of the extractor, thereby adsorbing at least a portion of lithium contained in the liquid flow in and / or onto the adsorbent material.

[0142] The liquid flow may be water produced during an industrial process (such as extracting oil and / or gas), or water from a brine lake, seawater, an aquifer, or a geothermal brine. The liquid flow may comprise at least one of lithium, silica, calcium, magnesium, sodium, potassium and other alkaline earth.

[0143] The method then comprises recovering S40 a flow depleted in lithium from the extractor.

[0144] The term "flow depleted in lithium" refers to a flow which has a lower concentration of lithium compared to the feed liquid flow (i.e., the liquid flow which has entered the extractor). In other words, the term "depleted in lithium" does not mean that the flow is completely free of lithium, and thus the flow depleted in lithium may contain residual lithium.

[0145] The method may optionally comprise recirculating S40' the flow depleted in lithium into the extractor. The recirculation of the flow depleted in lithium into the extractor for lithium extraction increases the recovery rate of lithium and decreases the water footprint (for example, the water consumption during the rinsing S70, which will be explained below).

[0146] The remaining components not adsorbed in and / or onto to adsorbent material may flow within said liquid through and exit the extractor.

[0147] The method then comprises passing S50 a desorbing solution into the extractor.

[0148] The desorbing solution may be selected suitably depending on the adsorbent material of the extractor. For example, the desorbing solution may be an acidic solution such as hydrochloric acid, sulfuric acid, phosphoric acid. When the method comprises recirculating S40' the flow depleted in lithium into the extractor, an alkaline solution such as sodium hydroxide, ammonium hydroxide or potassium hydroxide may be also used as a desorbing solution for desorbing, for example, impurities.

[0149] As an example, when the adsorbent material is an ion exchange adsorbent comprising a metal oxide, the desorbing solution may be an acidic solution.

[0150] The method comprising providing the extractor comprising a metal oxide adsorbent as the adsorbent material and passing an acidic solution as the desorbing solution allows for more efficient elution / regeneration (desorption) of the lithium, thereby resulting in an improved extraction capacity. The passing S50 of the desorbing solution into the extractor allows lithium to be eluted (desorbed) from the adsorbent material. Thus, the method comprises recovering S60 a stream enriched in lithium from the extractor.

[0151] The method may further comprise optionally rinsing S70 the extractor with water. For example, the method may comprise rinsing the extractor with water after the passing of the desorbing solution and recovering of the stream enriched in lithium from the extractor. The rinsing with water may effectively remove remaining traces of the desorbing solution used during the desorption, thereby restoring the efficiency of the adsorbent material. The method may comprise optionally repeating at least one of the passing S30 of the liquid flow into the extractor; recovering S40 of the flow depleted in lithium from the extractor; passing S50 of the desorbing solution into the extractor; and recovering S60 of the stream enriched in lithium from the extractor; and optionally rinsing S70 the extractor with water, in a continuous or batch mode. This increases the contact time between the liquid flow and the extractor, allowing for improved lithium recovery.

Claims

CLAIMS1. A liquid-phase lithium extractor (1), comprising: at least one membrane (2) including a lithium adsorbent material (3), and a plurality of conduits (5) formed by the at least one membrane and each configured for a liquid flow to pass through the conduit and contact the adsorbent material.

2. The extractor of claim 1, wherein the lithium adsorbent material comprises an ion exchange adsorbent.

3. The extractor of claim 1 or 2, wherein the ion exchange adsorbent comprises a metal oxide, preferably selected from titanium oxide, manganese oxide, and aluminium oxide hydroxide.

4. The extractor of any one of claims 1 to 3, wherein the at least one membrane comprises at least one of carbon fibers, glass fibers, metal, and a polymer.

5. The extractor of any one of claims 1 to 4, wherein the at least one membrane comprises a support layer coated with the adsorbent material, the support layer being made of at least one of carbon fibers, glass fibers, metal, and a polymer.

6. The extractor of any one of claims 1 to 5, wherein the at least one membrane comprises a binding material fixing the adsorbent material.

7. The extractor of any one of claims 1 to 6, wherein : the ratio of the conduit length to the conduit height is 100 to 10,000; and the ratio of the conduit width to the conduit height is 50 to 10,000.

8. The extractor of any one of claims 1 to 7, wherein the permeability of the extractor is from 1,000 to 40,000 Darcy under laminar flow conditions.

9. The extractor of any one of claims 1 to 8, wherein the at least one membrane comprises a stack of membrane layers.

10. The extractor of claim 9, wherein the stack of membrane layers consists of a stack of planar and / or parallel membrane layers.

11. The extractor of claims 9 or 10, wherein the plurality of conduits comprises a respective conduit between each pair of adjacent membrane layers.

12. The extractor of any one of claims 1 to 11, further comprising a plurality of separators (4), each fixed to the at least one membrane.

13. The extractor of claim 12, wherein the distance between two adjacent separators is in the range of 10 to 90 times the conduit height.

14. The extractor of claim 12 or 13, wherein the separator occupancy of the at least one membrane ranges from 1 % to 20% with respect to the total surface area of the membrane.

15. The extractor of any one of claims 12 to 14, wherein the flow resistance of the extractor caused by the separators is equal to or less than 20% with respect to the total flow resistance of the extractor.

16. The extractor of any one of claims 12 to 15, wherein the separators vary in size and / or shape.

17. The extractor of any one of claims 12 to 16, wherein each of the separators has an elongated shape having an aspect ratio of 2 to 6.

18. The extractor of any one of claims 12 to 17, wherein the at least one membrane comprises a stack of membrane layers, and the separators of one membrane layer ofthe stack are aligned with the separators of another membrane layer of the stack by at least 10%.

19. The extractor of any one of claims 12 to 18, wherein the at least one membrane comprises a plurality of separator occupancies.

20. The extractor of claim 19, wherein the separator occupancy at one section of the at least one membrane can be 20% to 200% greater than the separator occupancy of a different section of the membrane.

21. The extractor of any one of claims 1 to 20, comprising at least 10 membranes.

22. The extractor of any one of claims 1 to 21, wherein the conduit height distribution has a coefficient of variance in the range of from 1 % to 15%.

23. The extractor of any one of claims 1 to 22, further comprising at least two different conduit heights, wherein the difference in the conduit height is in the range of from 10% to 70%.

24. A method for extracting lithium from a liquid flow, comprising: providing (S10) the extractor of any one of claims 1 to 23; passing (S30) the liquid flow into the extractor; recovering (S40) a flow depleted in lithium from the extractor; passing (S50) a desorbing solution into the extractor; and recovering (S60) a stream enriched in lithium from the extractor.

25. The method of claim 24, further comprising orienting (S50) the extractor horizontally.

26. The method of claim 24 or 25, wherein the lithium adsorbent material comprises an ion exchange adsorbent.

1. The method of claim 26, wherein the ion exchange adsorbent comprises a metal oxide, preferably selected from titanium oxide, manganese oxide, and aluminium oxide hydroxide.

28. The method of any one of claims 24 to 27 , wherein the desorbing solution is an acidic solution.

29. The method of any one of claims 24 to 28, further comprising rinsing (S70) the extractor with water.

Images