Abstract
A method for extracting lithium from brine, said method comprising the steps of: providing a brine containing lithium; processing the brine to remove contaminants; submitting the brine to an electrochemical extraction of lithium; disposing of the lithium-depleted brine; adding water to the extracted lithium to create a lithium solution; performing an electrolytic alkylation on the lithium solution; exposing the lithium solution to crystallization and evaporation; and recovering the lithium salt resulting therefrom.
Claims
1. A method for extracting lithium from brine, said method comprising the steps of: providing a brine containing lithium; processing the brine to remove contaminants; submitting the brine to an electrochemical extraction of lithium; disposing of the lithium-depleted brine; recovery of the extracted lithium to produce a lithium solution; performing an electrolytic alkalization on the lithium solution; exposing the lithium solution to crystallization and evaporation; and recovering the lithium salt resulting therefrom.
2. The method of claim 1, wherein the electrochemical extraction of lithium is performed by exposing said brine to an appropriate lithium-intercalating electrode material under appropriate conditions for a period of time sufficient to selectively capture lithium ions present in the brine.
3. The method of claim 2, where the lithium ions extracted from the brine are released into a solution suitable for precipitation of a lithium salt product.
4. The method according to claim 2, where the lithium-intercalating electrode material is selected from the group consisting of: iron phosphate; manganese oxide; cobalt oxide; nickel manganese oxide; nickel manganese cobalt oxide; molybdenum disulfide; silicon; graphitic carbon, a suitable compound nanostructured or other lithium intercalating materials.
5. The method according to claim 2, where said precipitation can be induced and optimized through physical, chemical and/or electrochemical mechanisms in either the same unit operation or in a subsequent unit operation.
6. The method according to claim 2, where the concentrated lithium solution produced by electrode de-intercalation is subjected to one or more polishing steps to further condition the solution chemistry.
7. The method according to claim 2, where the electrochemical lithium intercalation and/or de-intercalation reaction is coupled to another electrochemical reaction which is oxidizing or reducing a component of the brine, resulting in an additional side product stream.
8. The method according to claim 2, where the electrochemical lithium intercalation and/or de-intercalation reaction is conducted using a roll to roll technique for manipulating electrode rolls.
9. The method according to claim 2, where the electrochemical lithium intercalation and/or de-intercalation reaction using suitable electrode active materials is facilitated by electrochemical pH alteration using alternate electrodes incorporated into the same process.
10. A process for managing a lithium-containing brine resource, wherein said process comprises a step of: pre-processing inlet fluids to remove contaminants; removing of lithium from said inlet fluid; and pumping said lithium-depleted brine into an appropriate formation for disposal.
11. The process for managing a lithium-containing brine resource according to claim 10, wherein said lithium-depleted brine is re-injected back into the resource for pressure support.
12. The process for managing a lithium-containing brine resource according to claim 10, further comprising a processing step to produce other elements from the lithium-depleted brine.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0044] Features and advantages of embodiments of the present application will become apparent from the following detailed description and the appended drawing, in which:
[0045] FIG. 1 is a diagram exemplifying a preferred embodiment of the process flow diagram described herein for extracting and processing lithium from brine;
[0046] FIG. 2 is a diagram exemplifying another preferred embodiment of the process flow diagram detailed herein for extracting and processing lithium from brine;
[0047] FIG. 3 is a diagram exemplifying another a preferred embodiment of the process flow diagram detailed herein for extracting and processing lithium from brine;
[0048] FIGS. 4 A-B are diagrams showing an example of the lithium extraction and salt precipitation process described herein, as well as some preferred embodiments of how multiple electrodes are incorporated together into a potential electrochemical system embodiment;
[0049] FIG. 5 depicts a potential embodiment of the process described herein whereby lithium extraction and lithium salt product precipitation are integrated into the same unit operation;
[0050] FIG. 6 demonstrates one potential embodiment of the process described herein whereby lithium extraction and recovery are integrated into the same unit operation using the roll to roll method without the need to cycle between brine and dilute electrolytes;
[0051] FIG. 7 illustrates one potential embodiment of the process described herein whereby the roll to roll electrochemical extraction and recovery method described herein in scaled up;
[0052] FIG. 8 is a diagram displaying one potential embodiment of the lithium extraction and concentration process whereby intercalating material on a conductive film roll is operated such that it can move from one side of the unit operation to another with a cleaning step to mitigate contamination;
[0053] FIGS. 9 A-D are some potential embodiments of the roll to roll lithium extraction and recovery process described herein;
[0054] FIGS. 10 A-B illustrate some potential embodiments of how the extraction of lithium using rolls of intercalating material can be scaled up;
[0055] FIGS. 11 A-D illustrate some potential embodiments of process described herein whereby a granular or similar form of the lithium-intercalating material is contacted with a conductive support or similar electrical connection for the electrochemical extraction and recovery steps;
[0056] FIG. 12 depicts preferred embodiments of process described herein whereby a granular or similar form of the lithium-intercalating material used to pack a process vessel on conductive porous trays is integrated with an electrochemical pH manipulation system built into the vessel walls;
[0057] FIG. 13 is a preferred embodiment whereby electrochemical lithium extraction, recovery and product salt precipitation are integrated into the same unit operation;
[0058] FIG. 14 illustrates a preferred embodiment for the lithium salt production process whereby brine is processed on site with modular unit operations and lithium saturated electrode rolls are used to produce salts at a central processing facility; and
[0059] FIGS. 15 A-B show the cathodic brine intercalation and anodic lithium de-intercalation unit operations respectively of a potential process embodiment whereby the roll to roll method and electrochemically induced precipitation are incorporated into the same unit operation.
[0060] Exemplary embodiments of the present invention will now be described below.
DETAILED DESCRIPTION
[0061] Throughout the following description, specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. The following description of examples of the invention is not intended to be exhaustive or to limit the invention of the precise forms of any exemplary embodiment. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
[0062] The present description relates to the extraction of lithium from brines to produce a lithium salt product.
[0063] FIG. 1 presents an exemplary process flow diagram illustrating a potential embodiment of the general flows of material and energy essential to the process proposed herein, where lithium-containing brines (10) are first pre-processed (12) to remove potential contaminants (13) of the electrochemical system including hydrocarbons, precipitating salts and reservoir gases amongst other possibilities, then subjected to an electrochemical extraction (14) process whereby lithium ions are selectively removed from the brine and released into a fresh, dilute solution. In the particular embodiment shown, formation of lithium hydroxide is achieved by an electrochemical alkalization (16) of the dilute solution by cathodic water electrolysis coupled with an appropriate anodic counter-reaction, which can be chosen and incorporated into the system by a number of potential embodiments and design parameters discussed in this document. Crystallization (18) can be conducted entirely or partially in the electrolytic alkalization chamber in embodiments which are designed to better handle solids, discussed herein, or can include subsequent processing operations to further condition or complete the precipitation of lithium hydroxide from the dilute solution produced by electronic de-intercalation in the electrochemical extraction step. Subsequent evaporation, spray drying, cyclone drying, and related unit operations will generally also be necessary to produce a high quality dry lithium salt product (19).
[0064] FIG. 2 depicts another exemplary process flow diagram whereby the ability to manipulate solution pH electrochemically is used to its full extent to enhance operational performance at each applicable step. After pre-processing (22) of the brine (20) to remove contaminants (23), potentially including hardness and other compounds which can precipitate at high pH, the brine can then undergo electrochemical alkalinisation (24). This can take many possible forms, but two potentialities of note include the use of a hydrogen generating, water splitting electrode operating at cathodic voltages to consume protons from the brine, or the use of alternative electrode materials such as graphite, nickel, and others to reduce and/or oxidize components in the brine depending on its composition such that the brine pH increases as the electrochemical reaction progresses. Such an increase in brine pH can facilitate the intercalation of lithium into particular electrode active materials such as manganese oxide, nickel manganese oxide and others. With multiple electrodes incorporated into the same unit operation and these electrodes operation managed by a central electrochemical control system, an additional electrode can be built into the same unit operation able to electrochemically lower the pH and de-intercalate the lithium from the active material, effectively recovering it to form a relatively pure aqueous lithium solution. Electrolytic hydrogen splitting (26) into protons is an electrochemical reaction able to lower the pH of an aqueous solution while not introducing any new ions into the system which would contaminate the purity of the final lithium salt product. In such an embodiment, due to the nature of the lithium-intercalating active material the final salt precipitation step by electrolytic alkalinisation (27) must be conducted in a separate unit operation from the electrochemical extraction (25) so as to avoid re-intercalation of the lithium into said active material. Again, water splitting is an electrochemical reaction able to modify aqueous pH without changing solution composition and consequently amenable to lithium salt precipitation with only energetic input and the potential of a hydrogen gas product which can be consumed in the electrochemical acidification step (26). Finally, a dry, saleable lithium product is produced by final crystallization, evaporation (29), spray drying and similar methods.
[0065] FIG. 3 shows a potential embodiment of the process described herein whereby a lithium-intercalating step utilizing a lithium-intercalating supercapacitor (33) material is used to provide an initial lithium concentration step before a subsequent lithium extraction (35) step accomplished by the electrochemical extraction techniques described herein. Supercapacitor materials include compounds such as graphite, molybdenum disulfide, silicon, and others as well as nanostructured derivatives of such materials and in general have faster lithium intercalation kinetics but potentially are less selective towards lithium versus other brine components often at hypersaline concentration. Therefore, it may be advantageous to combine an initial supercapacitor intercalation step which may be less selective but will result in a concentrated lithium concentration relative to the feed brine and may enhance overall throughput of the electrochemical extraction and recovery process which would then proceed as described herein.
[0066] FIG. 4A illustrates the general principles behind the selective electrochemical extraction of lithium from brines combined with an electrolytic alkalization process to generate lithium hydroxide. In the first step (41), a cathodic voltage or current is applied to an appropriate lithium-intercalating electrode material (47) which selectively absorbs lithium from the lithium-containing brine. In the second step (42), lithium is released back (48) into a dilute solution through the application of an anodic voltage or current which causes the lithium to de-intercalate from the electrode material. In the third step (43), an appropriate electrolytic electrode then activates under an applied cathodic voltage or current which drives an electrolytic reaction (45), such as hydrogen evolution, which increases the pH of the dilute lithium-containing solution. The fourth step (44) results from the first three as the dilute lithium-containing solution can then be driven to precipitate lithium hydroxide (46) at a sufficiently high pH. It is preferable that this entire process must be managed by an Electrochemical Control System (ECS) (40) which acts as an interface between the Distributed Control System (DCS) for the whole process and the electrochemical system. In order to apply currents and/or voltages the ECS must incorporate some galvanostatic and/or potentiostatic circuitry and equipment respectively.
[0067] FIG. 4B demonstrates some potential embodiments for how the lithium-intercalating and electrolytic electrodes can be incorporated into the same unit operation to operate in sequential fashion. Arrangement 405 depicts the case in which lithium-intercalating and electrolytic electrodes exist in the same vessel, unit operation or electrolyte container on separate trays, plates or similar structural supports which incorporate a current collector and provide electrical connections to the ECS. Arrangement 406 and 407 depict the case where lithium-intercalating and electrolytic electrodes are incorporated onto the same structural support, both with their own unique current collectors and electrical connections to facilitate separate operation of each by the ECS. Arrangement 408 illustrates a potential embodiment whereby both electrodes are incorporated into a radial arrangement such they have separated electrical connections in a structural hoop or similar which allows integration with the ECS. Such an embodiment may be able to be stacked concentrically, potentially interspaced with appropriate anodic electrodes/anolyte chambers, to create a radial tower or similarly scaled up cylindrical embodiment for the electrochemical extraction unit operation.
[0068] FIG. 5 depicts a preferred embodiment of the electrochemical lithium extraction and recovery process described herein integrated with electrolytic pH modifying electrodes in the same unit operation. In this particular embodiment, brine (51) and a dilute aqueous solution (52) are cycled between the two chambers (53 and 54) appropriately as otherwise described in this patent, while the multiple electrode system (55 and 55.sup.1) exists as a stack of modular trays holding lithium-intercalating and hydrogen generating, water splitting electrodes respectively. Therefore in this embodiment, after the lithium depleted brine has been drained the electrochemical control system can receive a signal from the distributed control system to initiate the lithium recovery procedure by applying an oxidative current to the lithium-intercalating electrode coupled with a cathodic, proton consuming electrochemical reaction at the electrolytic electrode which is kept electrically separate from the lithium-intercalating electrode with no connection other than through the electrochemical control system (56). The embodiment depicted herein has been modified to better conduct the precipitation of the lithium salt product in said unit vessel by incorporation of sloped sides leading to an outlet at the vessel base. Such embodiments can include other modifications to further facilitate the effective conveyance of slurries and granular materials such as augers, gate valves and similar techniques in standard practice. Lithium intercalation from brine can occur simultaneously with lithium de-intercalation and precipitation in the same unit operation in this particular embodiment, with operating changing sides during each cycle.
[0069] FIG. 6 disclose a preferred embodiment for the electrochemical system (611) which will remove lithium from the produced brine by absorbing those ions into cathodic electrode material. In this embodiment, the lithium-intercalating material exists on a current collector backing which is in a roll on a spindle and/or incorporated into a suitable cartridge such as the anodic feed roll (61) which can be loaded into the unit operation and fed into the electrochemical system with assistance of a spool with a gear, such as the anodic feed spool (62), which can assist the electrode tape stay in alignment as it feeds with the gear teeth gripping perforations in the electrode tape edge, similar to photographic film. The electrode tape then feeds into the anolyte chamber through the anodic rollers (63) before contacting the anodic current collector (64) at which time the lithium is de-intercalated into the dilute aqueous solution, after which this electrode tape is then fed out of the anolyte chamber by the anodic output spool (65) onto the anodic output roll (66). A parallel operation is occurring on the side of the catholyte chamber, which in this case contains the lithium-containing brine, whereby the cathodic feed roll (67) is fed into the brine tank and passes over a cathodic current collector (68), during which time it undergoes an applied cathodic current or voltage such that it is able to electrochemically intercalate lithium from the brine before being fed onto the cathodic output roll (69). In this embodiment, separating the anodic and cathodic containers is a membrane such as an anion exchange membrane which can help maintain relatively constant pH during the electrochemical process to preserve electrode stability. The application of current and/or voltage to the anodic and cathodic current collectors is conducted by the electrochemical control system, which incorporates potentiostatic and/or galvanostatic elements while also integrating with the overall distributed process control system.
[0070] FIG. 7 illustrates a preferred embodiment whereby the cathodic intercalation and anodic de-intercalation chambers are assembled in such a way as to resemble a convention cell stack. Contrary to conventional electrochemical cell designs however, in this embodiment the electrode material has been attached to a current collector sheet able to exist as a roll and the electrode roll (71 and 77) is fed into the cathodic intercalation or anodic de-intercalation chamber respectively depending on whether lithium is being selectively extracted from the brine (blue electrode rolls undergoing reduction) or is being stripped from the electrode into a dilute or deionized solution (red electrode rolls undergoing oxidation). Current is being supplied to the electrode tape as it passes through the system by contact with a current collector plate, connected to the electrochemical control system (ECS) (711), which specifies the applied voltage, current, or any combination of electrochemical parameters the system can potentially measure and respond towards to optimize operation. In this preferred embodiment, an additional chamber has been included as a means to post-process the electrode tape as it leaves the respective electrolytic chambers, particularly the brine containing intercalation chamber as contaminants may exist as a film on the surface of the cathodic electrode tape or sheet such as sodium or bromine which are undesirable. However, it may also be beneficial for quality control to also clean the anodic electrode tape before it enters the de-intercalation chamber to minimize introduction of dust or other contaminants which the electrode roll may come in contact with outside of the electrochemical system and may be unwanted in the de-intercalation solution which should be nearly pure lithium ions and water. Therefore, a processing chamber can potentially be introduced which cleans the electrode tapes, possibly using many mechanisms of cleaning action such as electrostatic force, chemical treatment, mechanical agitation or brushing, contact with nanostructured surfaces or materials, and many others which achieve the desired outcome of removing contaminants from the electrode as it enters or exits one or both of the intercalation and de-intercalation chambers. One advantage of this system is that the total lithium intercalation capacity of the process is dictated by the size and loading of the electrode sheet rolls rather than the total quantity of absorbent that can be packed into a tower or vessel, which is the conventional process of selective lithium extraction by a lithium-intercalating sorbent. Once either fully saturated with or depleted of lithium the rolls can then be interchanged from the anodic de-intercalation spindle to the cathodic intercalation spindle or vice versa with human, mechanical or robotic assistance depending on the spindle system design. Not shown in this potential embodiment is the piping and surrounding system designed to manage the influx and draining of brine and dilute or deionized solution into and out of the cathodic intercalation and anodic de-intercalation chambers respectively.
[0071] FIG. 8 discloses a potential embodiment of an electrochemical system designed to selectively extract lithium from brine, whereby the lithium-intercalating electrode exists on a tape or roll (801) on a spool or spindle. This electrode tape (801) is fed into the electrochemical system through rollers (802) with the assistance of a feed gear (803), which helps to maintain the electrode tapes alignment in the electrochemical system as the transit of the electrode tape is primarily driven by a motor powering revolution of the electrode product roll spindle (811). In this exemplary embodiment, the electrode tape passes over rollers with a current collector covering (804) over some or all of the spool surface. This current collector surface (404) is connected to the electrochemical control system (ECS) (812) which determines the current, voltage and/or potentially other electrochemical parameters of the connected current collectors. The electrode tape then passes through a membrane or physical barrier (805) using rollers (806) built into the electrochemical system structure to facilitate the electrode tapes transit without pulling on or otherwise interfering with the membrane or physical barrier. Use of a membrane allows transportation of cations or anions across the barrier during electrochemical operation which helps to minimize changes to anolyte/catholyte pH as the charge balances of the two chambers can be better equilibrated. However, in this potential embodiment a cleaning chamber has been incorporated between the two chambers to minimize contamination of brine into the dilute or deionized de-intercalation solution with the assistance of a mechanical brush (807) and potentially other cleaning mechanisms described herein, in which situation an impermeable physical barrier may be more appropriate, and pH will have to be managed with other chemical, electrochemical or other methods. The electrode tape then passes through another set of rollers (808) into the brine intercalation chamber to pass over another set of current collector rods (809), to be fed by the product roll gear (810) onto the electrode product roll spindle (811). Using the convention of FIG. 4 whereby blue electrode tapes are undergoing reduction and red electrode tapes oxidation, in this exemplary diagram the current collectors on the left hand, de-intercalation side (804) are turned off by the ECS while the right-hand side current collectors (809) in the brine intercalation will be turned on for the specific roll. The opposite case is then to be expected from the complementary system (814). Mixing of the catholyte and anolyte solutions by an agitator (813) or using a similar method improves the electrochemical kinetics happening at the electrode surfaces by reducing boundary layer effects. The advantage of the system illustrated is that once the electrode tapes have been fully fed through the system, they are immediately in a position to be fed back through the system the way they came, but the ECS will have reversed the current or voltage from performing a reductive intercalation to oxidative de-intercalation or vice versa, pulling lithium from the brine or stripping it back out of the electrode again cyclically. Not shown in this potential embodiment is the piping and surrounding system designed to manage the influx and draining of brine and dilute or deionized solution into and out of the cathodic intercalation and anodic de-intercalation chambers respectively.
[0072] FIG. 9A depicts a preferred embodiment of an electrochemical lithium extracting system using the methods described herein whereby the cathodic and anodic rolls are kept separate to the cathodic and anodic chambers respectively. In such an embodiment, the rolls can be physically moved from one side to another after they're totally filled/stripped, or the brine chamber can be refilled with dilute solution and vice versa between cycles.
[0073] FIG. 9B shows a preferred embodiment of the methods described herein whereby the anodic and cathodic electrode tapes are fed through to their respective sides during operation, such that they can be fed back through the opposite direction under the alternate applied voltage and/or current to intercalate or de-intercalate lithium from the electrodes during each cycle.
[0074] FIG. 9C illustrates a preferred embodiment of an electrochemical lithium extracting system using the methods described herein whereby the cathodic and anodic rolls are kept separate to the cathodic and anodic chambers respectively. In this embodiment, the smaller current collector spindles have been replaced by a single, large cylindrical current collector spindle over which the electrode tapes pass. Such a design might increase the amount of surface area actively conducting electrons and consequently facilitating the electrode reaction, thereby increasing the rate at which an electrode roll can be filled or depleted of lithium.
[0075] FIG. 9D demonstrates a preferred embodiment of an electrochemical lithium extracting system using the methods described herein whereby the cathodic and anodic rolls are kept separate to the cathodic and anodic chambers respectively and the current collector spindles have been replaced by a single, large elliptical current collector spindle over which the electrode tapes pass. Such a design might even further increase the electrode surface area participating in the electrode reaction at a given moment. In such a system, the tensile force on the electrode tape will have to be considered along with its bending stress as it passes over the sharper elliptical corners in order to minimize mechanical breakage of the electrode tape, particularly after many multiple cycles.
[0076] FIG. 10A disclosed herein is a preferred embodiment whereby the electrochemical intercalation and/or de-intercalation of lithium into electrode tapes from brine or into a dilute or deionized de-intercalation solution can be scaled up vertically in a tower design (1020). Electrode rolls (1005 can be stacked on one another in the form of cartridges, spools or spindles and fed into a large anolyte/catholyte tower depicted as the dotted cylindrical line. This tower can include a central current collector structure which the electrode tapes contact as they pass through the system. The current and/or voltage on these current collectors will be dictated by the electrochemical control system (ECS) (1010). Such a design may allow larger volumes of brine to be processed at once with a high surface area of electrode in contact with solution at any given time. In such a design, it may also be possible to collect the filled or depleted electrode rolls at the bottom once complete with fresh rolls fed into the top.
[0077] FIG. 10B demonstrates a preferred embodiment of the methods described in FIG. 10A but where cathodic intercalating rolls and anodic de-intercalating rolls (1005, 1005, 1005) can be incorporated into the same system to pass lithium from one another, likely with the conveyance of a dilute or largely deionized electrolyte solution filling the tower (1020). Such a system may be advantageous for subsequent polishing steps depending on the extent to which sodium or other contaminants may be picked up by the electrode surfaces or incorporate into the electrodes via competitive intercalation.
[0078] FIG. 11A presents a preferred embodiment of the methods described herein whereby the electrode material exists as a granular solid (1110) resting on a current collector (1112), over and/or through which the brine and de-intercalation solution (1100) pass alternately. Such an embodiment could exist as trays in a vessel through which fluid flows and lithium is extracted or released depending on the current and/or voltage applied to the current collector plate. Such an embodiment is an electrochemical extrapolation of conventional sorbent unit operations and methods. The vessel would likely require a layer of insulation between the packing and the metallic structure to prevent electrical shorts, losses or other safety and operational issues.
[0079] FIG. 11B illustrates a preferred embodiment of the methods described herein whereby the embodiment of FIG. 11A is modified to restrict the granular electrode sorbent and fluid flow (1100) to tortuous channels (1120) designed to increase the fluid's residence time in contact with the electrode material to further improve the processes efficacy. As with FIG. 11A, the current collector at the bottom of the channels will have an applied current and/or voltage in connection with an electrochemical control system as described above.
[0080] FIG. 11C shows a preferred embodiment of the methods described herein whereby the electrode material exists as a granular solid (1110) in contact with a mesh-like current collector (1130) to facilitate fluid flow (1100) through a vessel packed bed. In this and other potential embodiments it may be necessary to use an electrode material which has a higher fraction of conductive additives to address the additional current and mass transfer resistances present in the granular case in comparison to when the electrode material is calendared onto a current collecting sheet, tape or similar.
[0081] FIG. 11D depicts a preferred embodiment of the methods described herein whereby the electrode material is added as a surface coating onto a granular current collecting substrate for incorporation into a packed bed (1140) or similar vessel. Such a system would also require electrical connection to an electrochemical control system and electrical conduction through the packed bed would depend on the packing structure of the granular electrode-covered particles and how well they're connected in terms of contacting surface area. Such a design is advantageous in its simplicity as it is the electrochemical extension of the convention sorbent process but the electrical transport resistance in the packed bed may discourage such an operating paradigm.
[0082] FIG. 12 illustrates a preferred embodiment for the methods described herein whereby a packed bed or similar vessel (1204) is filled with a granular material (1206) incorporating lithium-intercalating electrode material on conductive porous trays (1208) incorporates electrochemical pH manipulation for enhanced operational performance. In such an embodiment, lithium-containing brine (1210) can be pumped into a process tower (1215), vessel or similar filled with a granular material (1206) somehow incorporating a lithium-intercalating active material, be it as part of a simple mixture with conductive material, as a surface coating on a conductive substrate, as part of a nanostructured material or other, sitting on or incorporated into a porous, conductive packing structure such as mesh trays or similar. This conductive bed (1213) must be connected to the electrochemical control system (1220) which manages the timing, voltage, current and other aspects of the electrode's electrical behaviour such that it can conduct reductive currents while in contact with brine to achieve effective intercalation and conduct oxidative currents to de-intercalate the lithium from the electrode into dilute aqueous solution. Incorporation of an additional electrode built into the unit operation structure, in this example the vessel wall, necessarily placed in a non-conductive fitting able to prevent short circuits or electrical connection to the packed bed, which is able to increase the brine pH, potentially by splitting water to convert protons into hydrogen, thereby facilitating enhanced lithium intercalation into particular active electrode materials. Not shown is the subsequent step, coordinated by the process control system, which involves completing drainage of lithium depleted brine (1230) followed by re-filling of the unit operation with dilute solution and lithium recovery by de-intercalation, which can also potentially be enhanced by electrolytic acidification using additional electrodes also incorporated into the unit operation.
[0083] FIG. 13 is an example of a preferred embodiment whereby the electrochemical lithium extraction, recovery and salt precipitation methods described herein are integrated together into modular unit operations able to generate a near saleable lithium salt product with only lithium-containing brine and electricity as inputs. In this embodiment, multiple electrodes (1301, 1303) are incorporated into a non-conductive radial structure (1317), within which conductive wires run to connect the two types of electrodes separately to the electrochemical control system (1310). Multiple such electrode wheels can be nested within each other's luminal space to fill the whole cylindrical volume and maximize active material surface area in contact with solution while the cylindrical tower design with conical bottom outlet (1319) can be particularly conducive to the conveyance of precipitated solids (1321), especially if additional modifications are included such as gate valves to manage the salt outlet stream. As with other embodiments in this patent, these unit operations would cycle between filling with lithium-containing brine and cathodic lithium intercalation activated by the electrochemical control system followed by draining of the lithium depleted brine, refilling of the vessel with a dilute aqueous solution followed by anodic de-intercalation of the lithium coupled with electrolytic alkalinisation to precipitate a lithium salt product. Both unit operations are depicted together to show how operation can be cycled between them.
[0084] FIG. 14 illustrates a preferred embodiment for the lithium production process described herein whereby lithium extraction from the brine (1404) is achieved by intercalation into electrode rolls (1406) in modular unit operations at the resource site, facilitated by the consumption of hydrogen gas (1408) which provides the anodic counter reaction to the cathodic lithium intercalation reaction. In this embodiment, once electrode rolls have become fully saturated with lithium they are transported to a central processing facility (1414) to undergo the reverse operation and yield a lithium salt product (1420), simultaneously producing hydrogen via electrolytic alkalinisation through water splitting which can then be transported back to the well sites with a small pipeline, by canisters or other vessels, or through other methods of gas transport to effectively provide an energetic input for the intercalation reaction. Pumping liquids is one of the main expenses of any lithium extraction operation and the modular design depicted in this embodiment may be able to reduce pumping costs by transporting electrode rolls (1425) instead, which can potentially replace hundreds of cubic metres of brine equivalent. Such an embodiment necessitates that hydrogen gas and lithium depleted electrode rolls are then sent back to field sites to continue the production cycle.
[0085] FIGS. 15A and 15B show two potential embodiments for the methods described herein whereby multiple electrode systems and the roll to roll method are incorporated into the same unit operation, with their function coordinated by the electrochemical and process control systems in concert. FIG. 15A depicts an embodiment where an electrode roll (1506) that does not contain lithium is fed into a brine containing chamber (1508) and subjected to a cathodic current by the electrochemical control system (1510) to achieve the selective interpolation of lithium into the electrode roll as it passes over the conducting rollers (1512), potentially made from a conductive material relatively suitable for electrochemical operation in saline fluids such as copper. In this embodiment, the cathodic intercalation reaction is coupled with an anodic hydrogen consuming reaction using an appropriate electrode material such as carbon, nickel, platinum, nanostructure materials or any one of many potential options, with hydrogen gas for the reaction supplied through an inlet incorporated into the unit operation. It is worthy of note that the active electrode material on the roll in this embodiment should not be the same active material used in embodiments depicted herein that use changes in pH to achieve intercalation/de-intercalation as the hydrogen consuming reaction will decrease the brine pH and consequently would shift the thermodynamic equilibrium of some active materials towards de-intercalation, inhibiting effective operation. Following depletion of lithium from the brine it can be drained (1525) from the vessel and potentially reinjected back into the formation or further processed to meet legal standards for disposal water compositions.
[0086] FIG. 15B illustrates a potential embodiment whereby the roll to roll method is coupled with an electrolytic hydrogen generating reaction to precipitate a lithium salt product (1530) while simultaneously recovering it from the electrode material absorbent used to extract it from the brine. This can be achieved by combining the anodic lithium de-intercalation reaction from an electrode roll while generating hydrogen using a cathodic reaction at a suitable counter electrode to increase the pH of the aqueous electrolyte. Such a system may require the addition of input energy from the electrochemical control system (1510.sup.1) but has the advantage of retaining product purity and resulting in the production of a potentially useful hydrogen gas product. The resulting lithium salt (1530) can then be conveyed out of an appropriately designed bottom outlet (1535) before further processing to result in a dry, saleable salt product.
[0087] While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be appreciated by those skilled in the relevant arts, once they have been made familiar with this disclosure that various changes in form and detail can be made without departing from the true scope of tie invention in the appended claims.
