Method and device for direct lithium extraction by adsorption in a simulated moving bed

Abstract

Method and device for a simulated moving bed extraction of lithium by adsorption using / comprising an extraction column (7) supplied with a feed (6) comprising lithium and a desorbent (9) for withdrawing an extract (10) and a raffinate (8), the column comprising an adsorbent solid (Ai) and being configured to operate in a closed loop, the feed and withdrawal points of the column being shifted over time by a value corresponding to a predetermined quantity of adsorbent solid with a permutation period and determining a plurality of operating zones of the column; according to the method, the extract is sent directly to an evaporation section (17) suitable for separating water (18) and producing a concentrate (19).

Description

[0001] Method and apparatus for direct extraction by adsorption of lithium in a simulated moving bed

[0002] technical field

[0003] The present invention relates to the field of lithium adsorption extraction in a simulated moving bed.

[0004] Previous technique

[0005] Demand for lithium has increased sharply in recent years, largely due to the rise of electric vehicles. To meet this demand, improving existing lithium extraction processes is essential. Lithium can be extracted from rocks or brines. In the case of brines, traditional processes are based on open-air evaporation, a slow and low-yield method. Adsorption processes have recently been developed and offer promising prospects.

[0006] Figure 1 shows a reference lithium adsorption extraction process. In an optional step A, a brine 1 is sent to a pretreatment section 2.

[0007] In a step B, the pretreated brine 6 (hereafter referred to as the feed) resulting from step A is sent to an extraction column 7 comprising a fixed bed of adsorbent on which lithium is adsorbed to produce a raffinate 8. The adsorbed lithium is then desorbed using an eluent (desorbent) 9, e.g., with water, to form an extract 10. Patent FR3053264A1 describes the preparation of such an adsorbent, of formula (LiCl)x.2Al(OH)3,nH2O with n being between 0.01 and 10, x being between 0.4 and 1, used in a process for extracting lithium from saline solutions. This type of adsorbent is generally used in cyclic adsorption and elution processes where brine flows through a column on which lithium is captured. The column is then fed with an eluent to desorb the desired lithium. The operating temperature is typically between 15 and 30°C.

[0008] In an optional step C, the extract 10 from step B is directed to a nanofiltration section 11 to increase the lithium content and separate a solution of unwanted salts 12.

[0009] In an optional step D, the filtered extract 13 from step C is directed to a reverse osmosis section 14 which will allow the separation of water 15 and the production of a lithium solution 16.

[0010] The concentration of the lithium 16 solution is increased in an optional step E in which the lithium 16 solution from step D is sent to an evaporation section 17 adapted to separate water 18. At the end of this step E, a concentrate 19 is obtained. The water 15 and / or 18 can optionally be recycled to the extraction column 7. In an optional step F, the concentrate 19 from this step E is sent to a purification section 20 adapted to separate at least a washing solution 21 and a purified concentrate 22.

[0011] In a step G, the purified concentrate 22 (or the extract 10 when none of the steps C to F are used) is sent to a precipitation section 25 in which lithium 26 is separated from a precipitation mother water 27 by precipitation.

[0012] Finally, part of the unwanted salt solution 12 and / or the wash solution 21 and / or the precipitation mother water 27 can be recycled to the pretreatment section 2.

[0013] It should be noted that depending on the composition of brine 1 (e.g. types of compounds present, salt contents), each of the steps A, C, D, E and F is optional.

[0014] It should be noted that step B, lithium adsorption, is the core of the process, which can be implemented in several ways. For example, patent FR3131225B1 proposes the use of a simulated moving bed to extract lithium while simultaneously purifying it and delivering a more concentrated flow, thus reducing the energy requirements of the downstream water evaporation steps.

[0015] However, the extraction by adsorption of lithium in a simulated moving bed can be improved.

[0016] Summary of the invention

[0017] In the context described above, a first object of the present invention is to overcome the problems of the prior art and to provide a method and device for lithium adsorption extraction in a simulated moving bed, enabling increased lithium concentration, thereby simplifying the extraction device equipment and resulting in significant energy savings. In particular, the method and device according to the invention eliminate the membrane operations considered essential in reference methods and devices.

[0018] According to a first aspect, the aforementioned objects, as well as other advantages, are obtained by a simulated moving bed lithium adsorption extraction process comprising the following step: at least one simulated moving bed lithium adsorption extraction column is fed with at least one charge comprising lithium and a desorbent, and at least one extract and at least one raffinate are withdrawn from at least one extraction column, at least one extraction column comprising an adsorbent solid, at least one extraction column being interconnected in a closed loop, the feeding and withdrawal points of the extraction column being shifted over time by a value corresponding to a predetermined quantity of adsorbent solid with a permutation period and determining a plurality of operating zones of at least one extraction column,and in particular the following main zones designated by definition by a number: a lithium desorption zone I comprising between a desorbent injection point and an extract withdrawal point; a zone II for the desorption of alkali metals other than lithium and / or alkaline earth metals comprising between the extract withdrawal point and a feed injection point; a lithium adsorption zone III comprising between the feed injection point and a raffinate withdrawal point; and a zone IV comprising between the raffinate withdrawal point and the desorbent injection point, a process in which the extract is sent directly (i.e., without an intermediate step) to an evaporation section adapted to separate water and produce a concentrate.

[0019] Advantageously, the present invention makes it possible to meet the current growth in electric mobility needs by providing a process for producing high-purity lithium, by extraction by simulated moving bed (SMB) lithium adsorption, simplifying downstream equipment requirements and providing significant energy savings.

[0020] Advantageously, the simulated moving bed lithium adsorption production process according to the invention makes it possible to produce a high quality lithium extract (purity >99.9%) meeting the specifications for battery production.

[0021] Advantageously, the Applicant has identified that the process according to the invention makes it possible to produce an extract particularly rich in lithium, notably with concentrations exceeding 5 g / l, or even 6 g / l. At such concentrations, the Applicant has also identified that it is possible to eliminate the nanofiltration and reverse osmosis sections of the reference schemes, thereby simplifying its downstream equipment requirements and resulting in energy savings.

[0022] According to one or more embodiments, a brine is sent into a pretreatment section for treatment (e.g. oxygenation and / or acidification) with an acidic compound, for example with sulfuric acid, in order to extract (e.g. by degassing, precipitation, filtration) any unwanted compounds, such as carbon dioxide and / or carbonate salts, and produce the feedstock.

[0023] In one or more embodiments, the evaporation section is adapted to separate water using forced vacuum evaporation or equivalent technology. In one or more embodiments, the concentrate has a lithium content of at least 15 g / L, preferably at least 25 g / L, and most preferably at least 35 g / L.

[0024] According to one or more embodiments, the water is recycled at least in part to the extraction column.

[0025] In one or more embodiments, the concentrate is sent to a suitable purification section to separate at least one washing solution and produce a purified concentrate. In one or more embodiments, boron is separated from the concentrate by solvent extraction, for example with a primary alcohol having six or more carbon atoms. In one or more embodiments, calcium and / or magnesium are separated from the concentrate by passing through an ion-exchange resin and elution with water.

[0026] In one or more embodiments, the purified concentrate is sent to a precipitation section in which lithium is separated from a precipitation mother liquor by precipitation, for example in the form of lithium carbonate, preferably of a quality suitable for battery use. In one or more embodiments, the precipitation section is fed with carbonates and optionally with water, e.g., Na₂CO₃.

[0027] According to one or more embodiments, part of the washing solution and / or the precipitation mother water is recycled to the pretreatment section.

[0028] According to one or more embodiments, at least one extraction column comprises a plurality of columns or adsorbers interconnected in a closed loop, the supply and withdrawal points of the columns or adsorbers being shifted over time by a value corresponding to one column or adsorber.

[0029] According to one or more embodiments, the plurality of columns or adsorbers comprises at least 4 columns or adsorbers, preferably between 4 and 24 columns or adsorbers, preferably between 8 and 21 columns or adsorbers, for example between 12 and 15 columns or adsorbers.

[0030] According to one or more embodiments, the adsorbent solid is distributed in zones I to IV according to configurations of type a / b / c / d, that is to say that the distribution of the adsorbent solid, in relation to the total quantity of adsorbent solid, is as follows: a is the quantity of adsorbent solid in zone I; b is the quantity of adsorbent solid in zone II; c is the quantity of adsorbent solid in zone III; and d is the quantity of adsorbent solid in zone IV, and: a = 43% ± 9%; b = 29% ± 6%; c = 14% ± 3%; and d = 14% ± 3%.

[0031] According to one or more embodiments, the at least one extraction column comprises a plurality of interconnected beds of solid adsorbent separated by trays, the feeding and withdrawal points in the trays of the extraction column being offset over time by a value corresponding to one bed of adsorbent.

[0032] According to one or more embodiments, at least one extraction column comprises at least 4 beds of adsorbent solid, preferably between 4 and 24 beds of adsorbent solid, preferably between 8 and 21 beds of adsorbent solid, for example between 12 and 15 beds of adsorbent solid.

[0033] According to one or more embodiments, the beds of solid adsorbent are distributed in zones I to IV according to configurations of type a / b / c / d, that is to say that the distribution of the beds of solid adsorbent is as follows: a is the number of beds in zone I; b is the number of beds in zone II; c is the number of beds in zone III; and d is the number of beds in zone IV, and: a = (t * 0.43) * (1 ± 0.20); b = (t * 0.29) * (1 ± 0.20); c = (t * 0.14) * (1 ± 0.20); and d = (t * 0.14) * (1 ± 0.20), t (the number of beds) being a natural integer between 4 and 24, preferably between 8 and 21, for example between 12 and 15 beds of solid adsorbent.

[0034] According to one or more embodiments, the adsorbent solid comprises at least one lithiaated aluminium oxyhydroxide Al0(OH) and / or at least one lithiaated aluminium hydroxide Al(OH)a.

[0035] In one or more embodiments, the adsorbent solid comprises, and preferably consists of, lithium bayerite and / or lithium boehmite. In one or more embodiments, the adsorbent solid comprises between 0.1% by weight and 5% by weight of lithium element, preferably in the form of LiCl, relative to the total weight of the adsorbent solid.

[0036] According to one or more embodiments, the adsorbent solid comprises and preferably consists of a solid material of formula (LiCl) x .2Al(OH)3,nH2O, where n is between 0.01 and 10, and x is between 0.4 and 1.

[0037] According to one or more embodiments, the desorbent is chosen from the group consisting of water, lithia water, brine, preferably water.

[0038] According to one or more embodiments, the desorbent comprises between 0 g / L and 1 g / L of lithium element, preferably in the form of LiCl, relative to the total weight of the desorbent.

[0039] According to one or more embodiments, the charge comprises at least 0.05 g / L weight of lithium element, preferably in the form of LiCl, relative to the total weight of the charge.

[0040] According to one or more embodiments, the steps of the process are carried out at a temperature (e.g. temperature in the adsorbent solid) between 0°C and 160°C, preferably between 0°C and 120°C and preferably between 5°C and 100°C, particularly preferably between 15°C and 80°C, very preferably between 40°C and 80°C, in particular to promote mass transfer.

[0041] Advantageously, the process steps are carried out at a controlled pressure (e.g., pressure in the adsorbent solid) so that the liquid phase remains constant throughout the process according to the invention. According to one or more embodiments, the pressure in the adsorbent solid beds is between 0.09 MPa and 5 MPa, preferably between 0.095 MPa and 3.5 MPa, and preferably between 0.1 MPa and 2.5 MPa.

[0042] According to one or more embodiments, the cycle duration is at least 20 minutes, preferably at least 40 minutes, such that it is between 1 hour and 10 hours. Preferably, the cycle duration is between 2 hours and 8 hours.

[0043] According to one or more embodiments, the ratio of the volumetric flow rate of the desorbent to the volumetric flow rate of the charge is less than 1, preferably less than 0.5, preferably less than 0.2, very preferably less than 0.1.

[0044] According to one or more embodiments, the ratio of the volumetric flow rate of the desorbent to the volumetric flow rate of the feed is between 0.01 and 1.0, preferably between 0.02 and 0.5, and most preferably between 0.06 and 0.1. According to a second aspect, the aforementioned objects, as well as other advantages, are obtained by a simulated moving bed lithium adsorption extraction device comprising the following elements: at least one simulated moving bed lithium adsorption extraction column adapted to be fed with at least one feed comprising lithium and a desorbent, and adapted to be withdrawn of at least one extract and at least one raffinate; at least one extraction column comprising a solid adsorbent; at least one extraction column being interconnected in a closed loop.the feed and withdrawal points of at least one extraction column being shifted over time by a value corresponding to a predetermined quantity of adsorbent solid with a permutation period and determining a plurality of operating zones of at least one extraction column, and in particular the following main zones designated by definition by a number: a lithium desorption zone I between a desorbent injection point and an extract withdrawal point; a zone II for the desorption of alkali metals other than lithium and / or alkaline earth metals between the extract withdrawal point and a feed injection point; a lithium adsorption zone III between the feed injection point and a raffinate withdrawal point; and a zone IV between the raffinate withdrawal point and the desorbent injection point.and an evaporation section adapted to receive the extract directly from at least one extraction column and produce water and a concentrate.

[0045] Other features and advantages of the invention, according to the aforementioned aspects, will become apparent from the following description and non-limiting examples of implementation, with reference to the figures attached and described below.

[0046] List of figures

[0047] Figure 1 represents a reference lithium extraction process.

[0048] Figure 2 represents a simulated moving bed lithium adsorption extraction process according to the invention.

[0049] Figure 3 represents a simulated moving bed lithium adsorption extraction process according to the invention, illustrating charge purification steps.

[0050] Figure 4 illustrates a simulated moving bed lithium adsorption extraction process according to the invention, using a plurality of simulated moving bed extraction columns. Figure 5 shows a simulated moving bed extraction column comprising a precipitation mother water recycling line.

[0051] Description of the implementation methods

[0052] Embodiments of the process and device according to the aforementioned aspects will now be described in detail. In the following detailed description, numerous specific details are presented to provide a more thorough understanding of the process and device. However, it will be apparent to those skilled in the art that the process and device can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0053] In this application, the term "include" is synonymous with (means the same as) "include" and "contain," and is inclusive or open-ended, not excluding other unstated elements. It is understood that the term "include" includes the exclusive and closed term "consist." Furthermore, in this description, the terms "essentially" or "substantially" correspond to an approximation of ±10%, preferably ±5%.

[0054] The present invention relates to a lithium adsorption extraction process employing a simulated countercurrent chromatography or simulated moving bed separation process, which we will hereafter collectively refer to as the "LMS" process. The lithium adsorption extraction process by simulated countercurrent chromatography or simulated moving bed described in this application may employ synchronous movement of the inlet / outlet lines, but may also employ asynchronous movement of the inlet / outlet valves in a multicolumn system, the latter being also known as VARICOL. In particular, the sequencing of injection and collection points takes place over one operating cycle of the device. Hereafter, the cycle time refers to the time it takes for the injection and collection points to be sequenced until they return to their initial positions within the device.At the end of a cycle, the device returns to its initial configuration. According to one or more embodiments, a cycle comprises as many periods as there are extraction columns or beds of adsorbent solid in the separation loop. For example, a cycle of an "LMS" process according to the invention comprising 8 extraction columns or 8 beds of adsorbent solid comprises 8 periods.

[0055] With reference to Figure 2, the process according to the invention proposes the implementation of a simulated moving bed lithium adsorption column 7, as well as the elimination of the nanofiltration 11 and reverse osmosis 14 sections of the reference design (see Figure 1). The use of a simulated moving bed for lithium extraction is already described in patent FR3131225A1. This invention advantageously utilizes this implementation to optimize the lithium extraction process as a whole. Indeed, we have identified that the implementation of a simulated moving bed adsorption column 7 makes it possible to achieve improved lithium concentrations and to eliminate the need for these membrane operations. These operations represent a significant investment cost and are prone to fouling. Furthermore, the membranes do not withstand temperatures above 50°C well, thus limiting the overall operation of the process.In addition, the removal of these membranes allows the process to be operated at temperatures between 40 and 80°C, improving the performance of lithium extraction (better mass transfer) and the evaporation stage (reduction of the vacuum level).

[0056] In particular, Figure 2 shows a lithium extraction process by adsorption. In an optional step I called pretreatment, a brine 1 is sent into a pretreatment section 2 for treatment (e.g. oxygenation and / or acidification), for example with an acidic compound 3, for example with sulfuric acid, in order to extract (e.g. by degassing, precipitation, filtration) any undesirable compounds, such as carbon dioxide 4 and / or carbonate salts 5, and produce the feed 6.

[0057] In a step II called extraction, the pretreated brine 6 (hereafter referred to as feed) resulting from step I is sent to an extraction column 7 comprising a fixed bed of adsorbent on which lithium is adsorbed to produce a raffinate 8. The adsorbed lithium is then desorbed using an eluent (desorbent) 9, e.g. with water, to form an extract 10. Patent FR3053264A1 describes the preparation of such an adsorbent, of formula (LiCl)x.2Al(OH)3,nH2O with n being between 0.01 and 10, x being between 0.4 and 1, used in a process for extracting lithium from saline solutions. This type of adsorbent is generally used in cyclic adsorption and elution processes where brine flows through a column on which lithium is captured. The column is then fed with an eluent to desorb the desired lithium. The operating temperature is typically between 15 and 30°C.

[0058] According to the invention, the concentration of the extract is increased in step III, the so-called concentration step, in which the extract 10 from step II is sent directly (i.e., without an intermediate step) to an evaporation section 17 adapted to separate water 18, for example, by forced vacuum evaporation technology, or equivalent, and produce a concentrate 19 preferably having a lithium content of at least 15 g / L, preferably at least 25 g / L, and most preferably at least 35 g / L. At the end of this step III, a concentrate 19 is obtained. The water 18 can optionally be recycled to the extraction column 7. Thus, according to the invention, there is no nanofiltration or reverse osmosis section between the extraction column 7 and the evaporation section 17.

[0059] In an optional purification step IV, the concentrate 19 from step III is sent to a purification section 20 adapted to separate at least one washing solution 21 and a purified concentrate 22. According to one or more embodiments, boron is separated from the concentrate 19 by solvent extraction 23, for example with a primary alcohol having 6 or more carbon atoms. According to one or more embodiments, calcium and / or magnesium are separated from the concentrate 19 by passing over an ion-exchange resin and elution with water 24. At least a portion of the washing solution 21 can be recycled to the pretreatment section 2. According to one or more embodiments, at least a portion of the washing solution 21 is purged, for example, to prevent the accumulation of impurities potentially present in the washing solution 21.

[0060] With reference to Figure 3, it should be noted that, according to the invention, step IV can be carried out at least partially between steps I and II. Thus, according to one or more embodiments, the feed 6 is sent to a pre-purification section 30 adapted to separate into a washing effluent 31 comprising: boron by solvent extraction 32; and / or calcium and / or magnesium by passing over an ion-exchange resin and elution with water 33, to produce a purified feed 34 directed to the extraction column 7. When step IV is carried out entirely between steps I and II, the concentrate 19 can be sent directly to the precipitation section 25 without further purification. At least part of the washing effluent 31 can be recycled to the pretreatment section 2.Preferably, at least part of the wash effluent 31 is removed from the process (see purge line 35), for example, to avoid the accumulation of impurities potentially present in the wash effluent 31.

[0061] In an optional concentration step V, the purified concentrate 22 (or concentrate 19) is sent to a precipitation section 25 where lithium 26 is separated from a precipitation mother liquor 27 by precipitation, for example, as lithium carbonate, preferably of a quality suitable for battery use. According to one or more embodiments, the precipitation section 25 is fed with carbonates 28 and optionally with water 29, e.g., Na2CO3. At least a portion of the precipitation mother liquor 27 can be recycled to the pretreatment section 2.

[0062] It should be noted that depending on the composition of brine 1 (e.g. types of compounds present, salt contents), each of steps I, IV and V is optional.

[0063] According to one or more embodiments, the LMS process and apparatus uses / includes at least one extraction column (or adsorbers), the column(s) arranged in series implementing a flow of fluids in a solid particle medium, called the adsorbent solid or granular medium, in a flow direction of the fluid(s) implemented in the column(s). The fluid passing through the column(s) successively is called the main fluid to distinguish it from other secondary fluids that may be added to the main fluid via a distribution and collection device (e.g., valve systems external to the column(s)), generally located at the column inlet or outlet, for example, between two successive columns.

[0064] With reference to Figure 4, according to one or more embodiments, the method and device according to the invention uses / comprising a plurality n of extraction columns 7 denoted \ (i.e., from column 7i to column 7) n separated by N dispensing devices (for the charge 6 and the desorbent 9) and collection devices (for the extract 10 and the raffinate 8). Preferably, the number n of columns and the number N of dispensing and collection devices are identical. In one or more embodiments, n is greater than or equal to 4. In one or more embodiments, n is between 4 and 24, preferably between 8 and 21, e.g., between 12 and 15. In one or more embodiments, N is greater than or equal to 4. In one or more embodiments, N is between 4 and 24, preferably between 8 and 21, e.g., between 12 and 15.

[0065] Referring to Figure 5, the LMS process and apparatus uses / includes an extraction column 7 implementing the flow of fluids through a plurality of beds of adsorbent solid Ai arranged in series according to the flow direction of the fluid(s) implemented in the column. The fluid successively passing through the beds of adsorbent solid Ai is called the main fluid to distinguish it from secondary fluids that can be added to the main fluid via a distribution and collection device, also called a tray Pi, generally located between two successive beds of adsorbent solid Ai.

[0066] A Pi tray includes at least one collection zone and a valve system for collecting the main fluid and / or injecting secondary fluids and mixing these secondary fluids with the main fluid. A tray also includes at least one distribution zone for distributing the fluid resulting from the mixing of the main fluid and secondary fluids onto the granular bed located immediately downstream, in the direction of the main fluid flow.

[0067] Referring to Figure 5, a column is divided into a plurality of trays Pi and adsorbent beds Ai, with tray Pi positioned directly upstream of the adsorbent bed Ai, in the direction of the main fluid flow. Furthermore, the term adsorbent bed Ai+1 refers to the next adsorbent bed located downstream of the adsorbent bed Ai, in the direction of the main fluid flow. Similarly, tray Pi+1 refers to the next tray located downstream of tray Pi, in the direction of the main fluid flow.

[0068] According to one or more embodiments, the method and device according to the invention use / comprising at least one column divided into n beds of adsorbent solid Ai separated by N trays (defining interbed zones), each tray being itself divisible into several sectors or regions, called panels. Preferably, the number n of beds of adsorbent solid Ai and the number N of trays Pj are identical. According to one or more embodiments, n is greater than or equal to 4. According to one or more embodiments, n is between 4 and 24, preferably between 8 and 21, e.g., between 12 and 15. According to one or more embodiments, N is between 4 and 24, preferably between 8 and 21, e.g., between 12 and 15.

[0069] In the following text, the term "step" refers to an operation or group of similar operations performed on a given flow at a specific point in the process. The process is described in its various steps, taken in the order in which the flows or products occur.

[0070] With reference to Figure 4, the simulated moving bed lithium adsorption extraction process according to the invention comprises the following step: one or more column(s) \ are fed with at least one charge 6 comprising lithium, denoted element A in Figure 4, and at least one alkali metal other than lithium and / or at least one alkaline earth metal, denoted element B in Figure 4; one or more column(s) \ are fed with a desorbent 9; at least one extract 10 is withdrawn from column \; at least one raffinate 8 is withdrawn from column 7j, the column(s) \ comprising an adsorbent solid.

[0071] With reference to figure 4, according to one or more embodiments, the solid adsorbent is distributed in the plurality of columns \ (eg adsorbers).

[0072] With reference to Figure 5, according to one or more embodiments, the adsorbent solid is distributed in the adsorbent solid beds Ai of at least one column 7, the adsorbent solid beds Ai being separated by trays Pi.

[0073] According to the invention, column 7 or columns 7j is / are interconnected in a closed loop, the supply and withdrawal points of the column(s) being offset over time (for example by a value corresponding to a column (e.g.adsorber) or an adsorbent bed of a column) with a permutation period and determining a plurality of operating zones of the column(s), and in particular the following main zones designated by definition by a number: a lithium desorption zone I between a desorbent injection point 9 and an extract withdrawal point 10; a non-lithium alkali metal desorption zone II and / or alkaline earth metal desorption zone between the extract withdrawal point 10 and a feed 6 injection point containing lithium; a lithium adsorption zone III between the feed 6 injection point and a raffinate withdrawal point 8, zone III being fed by the feed 6 as shown in Figure 4; and a zone IV between the raffinate withdrawal point 8 and the desorbent injection point 9;.

[0074] With reference to figure 4, according to one or more embodiments, the supply and withdrawal points of the columns \ are shifted over time by a value corresponding to a column \ (e.g. an adsorber).

[0075] With reference to Figure 5, according to one or more embodiments, the feed and withdrawal points of at least one column 7 are shifted over time by a value corresponding to an adsorbent bed Ai.

[0076] Advantageously, the process according to the invention allows the separation of lithium from alkali metals, preferably sodium (Na) and potassium (K), and from alkaline earth metals, preferably magnesium (Mg), calcium (Ca), and strontium (Sr), which are generally present in significant quantities in the saline solutions treated in said extraction process. The process according to the invention also allows the selective separation of lithium from other compounds such as boron and sulfates.

[0077] In one or more embodiments, the method / device implements / includes a plurality of interconnected columns or adsorbers in a closed loop. In one or more embodiments, the inlet and outlet points of the columns or adsorbers are offset over time by a value corresponding to one column or adsorber. In one or more embodiments, the method / device implements / includes at least 4 columns or adsorbers, preferably between 4 and 24 columns or adsorbers, preferably between 8 and 21 columns or adsorbers, e.g., between 12 and 15 columns or adsorbers.

[0078] According to one or more embodiments, the adsorbent solid is distributed in zones I to IV according to configurations of type a / b / c / d, that is to say that the distribution of the adsorbent solid, in relation to the total quantity of adsorbent solid, is as follows: a is the quantity of adsorbent solid in zone I; b is the quantity of adsorbent solid in zone II; c is the quantity of adsorbent solid in zone III; and d is the quantity of adsorbent solid in zone IV, with: a = 43% ± 9%, preferably ± 6%, very preferably ± 3%; b = 29% ± 6%, preferably ± 4%, very preferably ± 2%; c = 14% ± 3%, preferably ± 2%, very preferably ± 1%; and d = 14% ± 3, preferably ± 2%, most preferably ± 1%.

[0079] In one or more embodiments, the column or columns comprise a plurality of beds of solid adsorbent Ai interconnected in a closed loop and separated by trays Pj, the feed and withdrawal points in the trays Pj of the column being offset over time by a value corresponding to one bed of adsorbent. In one or more embodiments, at least one column comprises between 4 and 24 beds of solid adsorbent Ai, preferably between 8 and 21 beds of solid adsorbent Ai.

[0080] According to one or more embodiments, the beds of solid adsorbent Ai are distributed in zones I to IV according to configurations of type a / b / c / d, that is to say that the distribution of the beds of solid adsorbent Ai is as follows: a is the number of beds in zone I; b is the number of beds in zone II; c is the number of beds in zone III; and d is the number of beds in zone IV, with: a = (t * 0.43) * (1 ± 0.20, preferably 1 ± 0.10, most preferably 1 ± 0.05); b = (t * 0.29) * (1 ± 0.20, preferably 1 ± 0.10, most preferably 1 ± 0.05); c = (t * 0.14) * (1 ± 0.20, preferably 1 ± 0.10, most preferably 1 ± 0.05); and d = (t * 0.14) * (1 ± 0.20, preferably 1 ± 0.10, most preferably 1 ± 0.05), a method in which t is a natural integer between 4 and 24, preferably between 8 and 21, such that between 12 and 15.

[0081] According to one or more embodiments, the temperature is set so that the temperature in the adsorbent solid remains between 0°C and 160°C, preferably between 0°C and 120°C and preferably between 5°C and 100°C, particularly preferably between 15°C and 80°C, most preferably between 40°C and 80°C, in particular to promote accelerated perforation of the adsorbent solid.

[0082] Advantageously, the pressure is regulated so that the liquid phase remains constant throughout the process according to the invention. According to one or more embodiments, the pressure in the adsorbent solid is between 0.09 MPa and 5 MPa, preferably between 0.095 MPa and 3.5 MPa, preferably between 0.1 MPa and 2.5 MPa.

[0083] According to one or more embodiments, the cycle duration is at least 20 minutes, preferably at least 40 minutes, such that it is between 1 and 10 hours. Preferably, the cycle duration used is between 2 and 8 hours. The cycle duration corresponds to the permutation period ST (period between two successive permutations of feeds / extractions) multiplied by the total number of injection / withdrawal points, such as the total number of columns used (see example in Figure 4) or of adsorbent solid beds Ai used (see example in Figure 5).

[0084] According to one or more embodiments, the average recycling rate (i.e., ratio of the average recycling flow rate (average of zone flow rates weighted by the number of columns or beds of adsorbent solid per zone) to the charging flow rate) is between 2 and 12, preferably between 3 and 9, very preferably between 5 and 8.

[0085] According to one or more embodiments, the ratio of the volumetric flow rate of the desorbent to the volumetric flow rate of the filler is less than 1, preferably less than 0.5, preferably less than 0.2, most preferably less than 0.1. According to one or more embodiments, the ratio of the volumetric flow rate of the desorbent to the volumetric flow rate of the filler is between 0.01 and 1.0, preferably between 0.02 and 0.5, most preferably between 0.06 and 0.1.

[0086] According to one or more embodiments, the supply and withdrawal points of at least one column are offset synchronously.

[0087] According to one or more embodiments, the feed and withdrawal points of at least one column are shifted asynchronously. In this case, the cycle time refers to the time it takes for the injection and collection points to be sequenced until they return to their initial positions in the device. The amount of adsorbent solid contained in each of zones I, II, III, and IV, as defined above, is then calculated as the average amount of adsorbent solid contained in each zone over the cycle time. Similarly, the number of beds in each of zones I, II, III, and IV, as defined above, is calculated as the average number of adsorbent beds contained in each zone over the cycle time; this value may be a non-integer.

[0088] According to one or more embodiments, the charge comprises and preferably consists of a (saline) solution containing lithium and which may or may not be saturated with salts, such as a brine.

[0089] According to one or more embodiments, the charge comprises at least one of the following elements B: Na, K, Rb, Cs, Mg, Ca, Sr, Ba, F, Cl, Br, I, SO4, CO3, NO3, B, and HCO3. Said charge may be any natural saline solution, concentrated or obtained from a lithium extraction or processing method. For example, said saline solution used in the extraction method according to the invention may advantageously be chosen from brines of salt lakes or geothermal springs, brines subjected to evaporation to obtain concentrated lithium brines, seawater, effluents from lithium chloride or lithium hydroxide production plants, and effluents from lithium extraction processes from minerals.

[0090] In one or more embodiments, the charge comprises at least 0.05 g / L by weight of lithium element, preferably in the form of LiCl, relative to the total weight of the charge. In one or more embodiments, the charge comprises between 0.1 g / L and 1 g / L of lithium element, preferably in the form of LiCl, relative to the total weight of the charge.

[0091] In one or more embodiments, the desorbent is selected from the group consisting of water, lithium water, brine, and preferably water. In one or more embodiments, the desorbent comprises between 0 g / L and 1 g / L of lithium, preferably in the form of LiCl, relative to the total weight of the desorbent. In one or more embodiments, the desorbent comprises less than 0.05 g / L of lithium, preferably less than 0.01 g / L of lithium, relative to the total weight of the desorbent.

[0092] In one or more embodiments, the adsorbent solid comprises at least one lithiased aluminum oxyhydroxide Al₂O(OH)₃ and / or at least one lithiased aluminum hydroxide Al₂O(OH)₃. In one or more embodiments, the at least one lithiased aluminum oxyhydroxide Al₂O(OH)₃ comprises lithiased boehmite. In one or more embodiments, the at least one lithiased aluminum oxyhydroxide Al₂O(OH)₃ comprises at least 60% by weight, preferably at least 80% by weight, of lithiased boehmite, relative to the total weight of the at least one lithiased aluminum oxyhydroxide Al₂O(OH)₃. In one or more embodiments, the at least one lithiased aluminum oxyhydroxide Al₂O(OH)₃ consists of lithiased boehmite.

[0093] In one or more embodiments, the at least one lithiased aluminum hydroxide Al(OH)3 comprises lithiased bayerite. In one or more embodiments, the at least one lithiased aluminum hydroxide Al(OH)3 comprises at least 60% by weight, preferably at least 80% by weight, of lithiased bayerite, relative to the total weight of the at least one lithiased aluminum hydroxide Al(OH)3. In one or more embodiments, the at least one lithiased aluminum hydroxide Al(OH)3 consists of lithiased bayerite.

[0094] In one or more embodiments, the adsorbent solid comprises at least 0.1% by weight of lithium (preferably in the form of LiCl), preferably at least 1% by weight, and most preferably at least 1.5% by weight, relative to the total weight of the adsorbent solid. In one or more embodiments, the adsorbent solid comprises between 0.1% by weight and 5% by weight of lithium (preferably in the form of LiCl), preferably between 1% by weight and 4% by weight, and most preferably between 1.5% by weight and 3% by weight, relative to the total weight of the adsorbent solid.

[0095] According to one or more embodiments, the adsorbent solid comprises and preferably consists of a solid material of formula (UCI) x .2Al(OH)3,nH2O, in which n is between 0.01 and 10, and x is between 0.4 and 1. According to one or more embodiments, n is between 0.1 and 5, preferably between 0.1 and 1, most preferably between 0.1 and 0.5.

[0096] According to one or more embodiments, the adsorbent solid has a specific surface area characterized by nitrogen adsorption according to the BET method, between 1 m 2 / g and 30 m 2 / g, preferably between 1 m 2 / g and 20 m 2 / g.

[0097] In one or more embodiments, the adsorbent solid is in the form of beads or extrudates of cylindrical, hollow cylinder, wheel-shaped, trilobed, or multilobed shape, or any other geometric shape understood by those skilled in the art. In one or more embodiments, the adsorbent solid is in the form of beads with an average diameter of between 0.1 mm and 1.5 mm, preferably between 0.1 mm and 1 mm, and more preferably between 0.3 mm and 0.8 mm. In one or more embodiments, the adsorbent solid is in the form of extrudates with a diameter of between 0.15 mm and 5 mm, preferably between 0.2 mm and 3 mm, and more preferably between 0.5 mm and 1.0 mm.

[0098] The solid adsorbent material is characterized using the following techniques: nitrogen adsorption for determining the specific surface area according to the BET method (e.g., ASTM D 3663-7); and X-ray fluorescence for elemental analysis. The average diameter of the extrudates is measured optically on at least 10 extrudates, preferably at least 50. For example, when the solid adsorbent is in the form of beads, the number-average diameter of the adsorbent is estimated by analyzing the particle size distribution of a sample of at least 50 adsorbent beads using imaging according to ISO 13322-2:2006, with a conveyor belt allowing the sample to pass in front of the camera lens. The number-average diameter is then calculated from the particle size distribution by applying ISO 9276-2:2001.

[0099] Examples

[0100] The process according to the invention is applied for the purification and separation of a lithium brine containing 0.4 g / L of element lithium, 110 g / L of element chlorine and 70 g / L of element sodium.

[0101] In process A (reference), the feed, after pretreatment, is sent to a simulated moving bed comprising two injections (feed and desorbent) and two withdrawals (extract and raffinate) in a 9 / 6 / 3 / 3 configuration. The adsorbent used is lithium-rich Bayerite at 20 °C. The lithium-rich extract is sent to a nanofiltration stage followed by reverse osmosis before evaporation. A precipitation stage then reforms lithium carbonate. The mother liquors resulting from this last stage are recycled back to the feed at the process inlet.

[0102] In Process B (the invention), the nanofiltration and reverse osmosis membrane steps are eliminated; the rest of the process is identical to the reference process. Process B produces lithium of the same quality as Process A. Maintenance downtime is also reduced compared to Process A. This is because the membranes in Process A become easily fouled and must be changed several times a year.

Claims

1. Demands 1. A simulated moving bed lithium adsorption extraction process comprising the following step: at least one column (Ci) is fed with at least one charge (6) comprising lithium and a desorbent (9), and at least one extract (10) and at least one raffinate (8) are withdrawn from the column (Ci), the at least one column (Ci) comprising a sorbent solid, the at least one column (Ci) being interconnected in a closed loop, the feed and withdrawal points of the at least one column (Ci) being shifted over time by a value corresponding to a predetermined quantity of absorbent solid with a permutation period and determining a plurality of operating zones of the column (Ci), and in particular the following principal zones designated by definition by a number: a lithium desorption zone I comprising a desorbent injection point (9) and an extract withdrawal point (10);a zone II for the desorption of alkali metals other than lithium and / or alkaline earth metals comprising between the point of withdrawal of the extract (10) and a point of injection of the feed (6) comprising lithium; a zone III for the adsorption of lithium comprising between the point of injection of the feed (6) and a point of withdrawal of the raffinate (8); and a zone IV is comprised between the point of withdrawal of the raffinate (8) and the point of injection of the desorbent (9), a process in which the extract (10) is sent directly into an evaporation section (17) adapted to separate water (18) and produce a concentrate (19).

2. A method according to claim 1, wherein at least one column (Ci) comprises a plurality of columns (Ci) or adsorbers interconnected in a closed loop, the supply and withdrawal points of the columns (Ci) or adsorbers being shifted over time by a value corresponding to one column (Ci) or one adsorber.

3. Method according to claim 1 or claim 2, wherein the plurality of columns (Ci) or adsorbers comprises at least 4 columns or adsorbers.

4. A method according to any one of the preceding claims, wherein the absorbent solid is distributed in zones I to IV according to configurations of type a / b / c / d, that is to say that the distribution of the absorbent solid, with respect to the total quantity of absorbent solid, is as follows: a is the quantity of absorbent solid in zone I; b is the quantity of absorbent solid in zone II; c is the quantity of adsorbent solid in zone III; and d is the quantity of adsorbent solid in zone IV, process in which: a = 43% ± 9%; b = 29% ± 6%; c = 14% ± 3%; and d = 14% ± 3%.

5. Method according to claim 1, the at least one column (Ci) comprises a plurality of beds of solid adsorbent (Ai) interconnected in a closed loop and separated by trays (Pi), the feeding and withdrawal points in the trays (Pi) of the column (Ci) being shifted over time by a value corresponding to one bed of adsorbent.

6. Method according to claim 5, wherein at least one column (Ci) comprises between 4 and 24 beds of solid adsorbent (Ai).

7. A method according to claim 5 or claim 6, wherein the beds of solid adsorbent (Ai) are distributed in zones I to IV according to configurations of type a / b / c / d, that is to say that the distribution of the beds of solid adsorbent (Ai) is as follows: a is the number of beds in zone I; b is the number of beds in zone II; c is the number of beds in zone III; and d is the number of beds in zone IV, a method in which: a = (t * 0.43) * (1 ± 0.20); b = (t * 0.29) * (1 ± 0.20); c = (t * 0.14) * (1 ± 0.20); and d = (t * 0.14) * (1 ± 0.20), a method in which t is a natural number between 4 and 24.

8. A process according to any one of the preceding claims, wherein the adsorbent solid comprises at least one lithium aluminum oxyhydroxide Al₂O(OH)₃ and / or at least one lithium aluminum hydroxide Al₂O(OH)₃.

9. A method according to any one of the preceding claims, wherein the adsorbent solid comprises lithium bayerite and / or lithium boehmite.

10. A method according to any one of the preceding claims, wherein the adsorbent solid comprises between 0.1 wt% and 5 wt% of lithium element, relative to the total wt% of the adsorbent solid.

11. A method according to any one of the preceding claims, wherein the adsorbent solid comprises a solid material of formula (LiCl) x .2Al(OH)3,nH2O, where n is between 0.01 and 10, and x is between 0.4 and 1.

12. A method according to any one of the preceding claims, wherein the charge (6) comprises at least 0.05 g / L weight of lithium element, relative to the total weight of the charge.

13. A process according to any one of the preceding claims, wherein the steps of the process are carried out at a temperature between 0°C and 160°C.

14. A method according to any one of the preceding claims, wherein the ratio of the volumetric flow rate of the desorbent (9) to the volumetric flow rate of the charge (6) is less than 1.

15. Simulated moving bed lithium adsorption extraction device comprising the following elements: at least one simulated moving bed lithium adsorption extraction column (7) adapted to be fed with at least one charge (6) comprising lithium and a desorbent (9), and adapted to be withdrawn of at least one extract (10) and at least one raffinate (8), the extraction column (7) comprising an adsorbent solid, the extraction column (7) being interconnected in a closed loop, the feed and withdrawal points of the extraction column (7) being offset over time by a value corresponding to a predetermined quantity of adsorbent solid with a permutation period and determining a plurality of operating zones of the extraction column (7),and in particular the following main zones designated by definition by a number: a lithium desorption zone I comprising between a desorbent injection point (9) and an extract withdrawal point (10); a lithium alkali metal desorption zone II comprising between the extract withdrawal point (10) and a feed injection point (6); a lithium adsorption zone III comprising between the feed injection point (6) and a raffinate withdrawal point (8); and a zone IV comprising between the raffinate withdrawal point (8) and the desorbent injection point (9), and an evaporation section (17) adapted to receive the extract directly from the extraction column (7) and produce water (18) and a concentrate (19).

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