Method and apparatus for producing high purity lithium carbonate

Abstract

A method for producing lithium carbonate from aqueous solutions feedstocks includes extracting lithium from an aqueous solution with an organic phase to form a lithium loaded organic phase, stripping the lithium loaded organic phase formed from extracting lithium, de-oiling a solid lithium carbonate or a stripped aqueous lithium bicarbonate phase formed from stripping, and processing a solid formed from de-oiling the solid lithium carbonate or a liquid formed from de-oiling the liquid lithium bicarbonate to obtain a battery-grade lithium carbonate. A system for stripping loaded lithium organic phases to produce lithium carbonate includes a reaction tank, a multiphase dispersion contact reactor, a suspension recirculation system, a carbon dioxide recirculation system and a de-oiling system.

Description

METHOD AND APPARATUS FOR PRODUCING HIGH PURITY LITHIUM CARBONATEBACKGROUND

[0001] Lithium is pivotal in the global energy transition due to its integral role in lithium-ion batteries, which power electric vehicles (EVs) and serve as crucial energy storage solutions for renewable energy sources like solar and wind. These batteries enable longer driving ranges and faster charging times for EVs, while also stabilizing the grid by smoothing out fluctuations in renewable energy generation. Beyond transportation and renewable energy, lithium batteries support grid energy storage projects, improve energy efficiency in portable electronics, and drive ongoing research and development for enhanced performance and sustainability. As the world moves towards cleaner and more sustainable energy systems, lithium's versatility and efficiency in energy storage technologies continue to underpin advancements in achieving a low-carbon future.

[0002] Lithium primarily occurs in two main types of sources: brine deposits and hard rock (lithium-bearing minerals). Brine deposits, found predominantly in salt flats or salars, contain concentrated lithium-rich solutions that can be pumped to the surface and processed. These brines often coexist with other salts such as potassium and magnesium. Hard rock lithium deposits, on the other hand, include lithium-bearing minerals like spodumene and pegmatites. These minerals are mined from open pits or underground mines and then processed to extract lithium through a series of steps including crushing, grinding, and chemical treatment. Additionally, lithium recovery from secondary sources, such as recycled batteries and other lithium-containing products, is an emerging and increasingly important aspect of the lithium supply chain.

[0003] Lithium recovery from brines, hard rocks, and secondary resources often involves extracting lithium from solutions or materials with relatively low concentrations of lithium. While brines are naturally more concentrated than seawater, the lithium concentration can still vary and may range from around 0.1 g / L to 1 g / L or higher. Lithium recovery from secondary sources, such as recycled batteries, also deals with low concentration solutions of lithium. Used batteries contain lithium in various forms, but typically at concentrations much lower than those found in primarysources. The recycling process involves dismantling batteries, separating materials, and then using hydrometallurgical methods to extract and purify lithium from these low concentration solutions. During hydrometallurgical processing, the mixed cathode and anode materials are typically dissolved in an acid solution first in the presence or absence of reducing agent. Lithium concentration in the dissolved solution is also relatively low, typically in the range of 0.5 g / L to 2 g / L.

[0004] Lithium concentration and purification from low-concentration solutions are challenging and cost intensive. For instance, in the battery recycling industry, evaporation is typically employed to concentrate lithium from 0.5-2 g / L to 20-40 g / L by removing water. This concentration step is essential because it reduces the volume of solution needing further processing, thereby increasing the efficiency and effectiveness of subsequent purification steps. However, achieving these higher concentrations involves energy-intensive processes, such as heating and evaporation, which can contribute significantly to the overall cost of lithium recovery from secondary sources. Therefore, more efficient and cost-effective technologies are required for lithium concentration and purification from low-concentration solutions.

[0005] Additionally, upgrading industrial-grade lithium carbonate to battery-grade suffers from several disadvantages, such as high costs, energy intensity, and the necessity for harsh reaction conditions. The industry typically employs the carbonate refinement method for this purpose, leveraging the solubility differences between lithium and impurities in the presence of carbon dioxide. During the carbonate refinement process, a crude lithium carbonate product is dispersed in water to react with carbon dioxide under controlled conditions (temperature, pressure, pH, etc.). High temperature and high pressure are typically required during carbonate refinement, resulting in significant operating costs and carbon emissions.

[0006] Overall, there remains a need for innovative technologies to efficiently concentrate and purify lithium from aqueous solutions, especially those with low lithium concentrations, and to produce battery-grade lithium carbonate.SUMMARY

[0007] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identifykey or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0008] In one aspect, embodiments described herein are directed to a method for producing lithium carbonate from aqueous solutions feedstocks includes extracting lithium from an aqueous solution with an organic phase to form a lithium loaded organic phase, stripping the lithium loaded organic phase formed from extracting lithium, wherein the stripping is performed at a temperature ranging from 5°C to 80°C and with a solution comprising dissolved lithium carbonate or lithium bicarbonate, deoiling a solid lithium carbonate or a stripped aqueous lithium bicarbonate phase formed from stripping, and processing a solid formed from de-oiling the solid lithium carbonate or a liquid formed from de-oiling the liquid lithium bicarbonate to obtain a batterygrade lithium carbonate.

[0009] In another aspect, embodiments described herein are directed to a system for stripping loaded lithium organic phases to produce lithium carbonate includes a reaction tank, a multiphase dispersion contact reactor, a suspension recirculation system, a carbon dioxide recirculation system and a de-oiling system.

[0010] Other systems, methods, features, and advantages of the present disclosure will be apparent to those skilled in the art upon reviewing the accompanying drawings and detailed descriptions. It is understood that all such additional systems, methods, features, and advantages are encompassed by this disclosure, fall within the scope of the present invention, and are protected by the accompanying claims. Furthermore, all optional and preferred features and modifications described herein can be applied across all aspects of the invention. Moreover, the specific features of dependent claims, as well as optional and preferred features and modifications of the disclosed embodiments, can be combined and interchanged with each other.BRIEF DESCRIPTION OF THE FIGURES

[0011] FIG. l is a process flow diagram based on low aqueous to organic volume ratio (A / O) CO2 stripping to produce lithium carbonate from solutions that contain lithium in accordance with one or more embodiments.

[0012] FIG. 2 is a process flow diagram based on high A / O volume ratio stripping to produce lithium bicarbonate-rich solutions, followed by solid lithium carbonate, from solutions that contain lithium in accordance with one or more embodiments.

[0013] FIG. 3 is a system that may be used to directly produce battery-grade lithium carbonate from an organic phase loaded with lithium in accordance with one or more embodiments.

[0014] FIG. 4 is a system that may be used to produce lithium bicarbonate-rich solution, followed by solid lithium carbonate, from an organic phase loaded with lithium in accordance with one or more embodiments.

[0015] FIG. 5 is another system that may be used to produce lithium bicarbonate-rich solution, followed by solid lithium carbonate, from an organic phase loaded with lithium in accordance with one or more embodiments.DETAILED DESCRIPTION

[0016] The disclosure is not limited to particular embodiments described, and as such may, of course, vary. The terminology used herein serves the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

[0017] As those having ordinary skill in the art will appreciate, different persons may refer to the same feature by different names. This document does not intend to distinguish between features that differ in name but not function. The figures are not necessarily drawn to scale. Certain features here may be shown in somewhat schematic form and some details may not be shown in the interest of clarity and conciseness.

[0018] Those having ordinary skill in the art will appreciate that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0019] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenienceonly and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0020] Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of organic chemistry, inorganic chemistry, biology, and the like, which are within the skill of the art. Such techniques are explained fully in the literature.

[0021] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to perform the methods and use the compositions and compounds disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.), but some errors and deviations should be accounted for.

[0022] Before the embodiments of the present disclosure are described in detail, it is to be understood that, unless otherwise indicated, the present disclosure is not limited to particular materials, reagents, reaction materials, manufacturing processes, dimensions, frequency ranges, applications, or the like, as such can vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only and is not intended to be limiting. It is also possible in the present disclosure that steps can be executed in different sequence, where this is logically possible. It is also possible that the embodiments of the present disclosure can be applied to additional embodiments involving measurements beyond the examples described herein, which are not intended to be limiting. It is furthermore possible that the embodiments of the present disclosure can be combined or integrated with other measurement techniques beyond the examples described herein, which are not intended to be limiting.

[0023] As used in the discussion and the appended claims, the singular form “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. For example, reference to “a solvent extraction system,” “an oxidizing agent,” or “the black mass material” includes, but is not limited to, two or more such solvent extraction systems, oxidizing agents, or black mass materials, and the like.

[0024] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0025] It should be noted that ratios, temperatures, pH values, and other numerical data can be expressed herein in a range format. It will be further understood that the end points of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It will be also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “60” is disclosed, then “about 60” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another value. Similarly, when values are expressed as approximations, by the use of the antecedent “about”, it will be understood that the particular value forms a further aspect. For example, if the value “about 60” is disclosed, then “60” is also disclosed.

[0026] When a range is expressed, a further aspect includes from one particular value and / or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g., the phrase “x to y” includes the range from “x” to “y” as well as the ranges greater than “x” and less than “y”. In addition, the phrase “about x to y”, where “x” and “y” are numerical values, includes “about x” to “about y.”

[0027] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a concentration range of “about 0.1 percent to 0.5 percent” should be interpreted to include not only the explicitly recited concentration of about 0.1 percent to about 0.5 percent but also include individual concentrations (e.g., 1 percent, 2 percent, 3 percent, and 4 percent) and the sub-ranges (e.g., 0.5 percent, 1.1 percent, 2.2 percent, 3.3 percent, and 4.4 percent) within the indicated range. The term “about” can include traditional rounding according to significant figures of the numerical value. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ to ‘about y’”.

[0028] Furthermore, the terms “about,” “several,” “multiple,” “a number of,” “some,” “at or about,” “substantially,” “mainly,” “primarily,” and “minimal” as used hereinmean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not to be exact but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variations unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “several,” “multiple,” “a number of,” “some,” “at or about,” “substantially,” “mainly,” “primarily,” and “minimal” whether or not expressly stated to be such. It is understood that where “about” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0029] In the following discussion and in the claims, the terms “such as”, “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . ..”

[0030] As used herein, “contaminants” or “impurities” refers to undesired materials in the final products. Contaminants and impurities include, but are not limited to aluminum, copper, calcium, magnesium, titanium, silicon, zinc, sulfur, and fluoride.

[0031] As used herein, “undesired constituents” refers to contaminants, including but not limited to lithium, nickel, cobalt, manganese, iron, and phosphorus.

[0032] As used herein, “battery-grade” refers to the purity and other specifications of the products that meet the standards of being used for battery manufacturing.

[0033] As used herein, “solvent extraction” refers to metal separation and concentration by mixing two immiscible phases, typically an aqueous phase and an organic phase. During the mixing process, metal ions transfer from one phase to another.

[0034] As used herein, “aqueous phase” refers to the phase with higher density during the solvent extraction process. It is used interchangeably with “aqueous solution” and “solution” in this disclosure.

[0035] As used herein, “organic phase” refers to the phase with lower density during the solvent extraction process.

[0036] As used herein, “loaded organic phase” refers to an organic phase containing metal ions.

[0037] As used herein, “extractant” refers to the active organic compounds present in the organic phase that can selectively interact with selected types of metal ions.

[0038] As used herein, “diluent” refers to the organic chemicals used to dissolve the extractant.

[0039] As used herein, “scrubbing” refers to the removal of undesired constituents from a loaded organic phase by mixing with an appropriate aqueous solution.

[0040] As used herein, “stripping” refers to the removal of target valuables from the organic phase.

[0041] As used herein, “oil” or “organic compounds” refers to the chemicals present in the organic phase.

[0042] The present disclosure relates to methods and systems for producing batterygrade lithium carbonate from aqueous feedstocks, including leachates, natural brines, industrial wastewaters, and recycled lithium sources. The method involves solvent extraction of lithium ions from an optionally pretreated aqueous feedstock into an organic extractant phase before subsequently stripping the lithium from the loaded organic phase into an aqueous phase using carbon dioxide. Stripping is performed under a multiphase dispersion contact reaction wherein microbubbles of carbon dioxide and microdroplets of liquid phase organic extractant and aqueous stripping solution are brought into contact under high surface area-to-volume ratios, facilitating rapid and efficient precipitation of lithium carbonate either directly or through intermediate lithium bicarbonate formation. Following stripping, the invention includes steps for separating and de-oiling the solid lithium carbonate product and processing it to meet battery -grade specifications through washing and drying steps.One or more embodiments of the invention represent an integrated system combining conventional approaches with an innovative multiphase dispersion contact reaction wherein high shear forces promote gas-liquid interactions essential to rapidly and efficiently perform carbon dioxide stripping of lithium at scale. The system includes modules for carbon dioxide recirculation, suspension mixing, de-oiling, and optional decomposition of lithium bicarbonate. Configurations may employ venturi tubes, spargers, or high-pressure reactors to enhance process efficiency and selectivity.

[0043] Embodiments disclosed herein include processes and systems designed for the production of battery grade lithium carbonate. These processes all include extracting lithium from a lithium-containing solution using solvent extraction to obtain a lithium- containing organic phase, but either, in the case of the low A / O volume ratio method (FIG. 1), stripping lithium from the organic phase to directly produce solid lithium carbonate or, in the case of the high A / O volume ratio method (FIG. 2), forming a lithium bicarbonate rich solution, and finally producing solid lithium carbonate from that solution. The solubility of lithium carbonate determines whether a low A / O CO2 stripping or high A / O CO2 stripping description is appropriate. As described herein, if the lithium concentration is under approximately 9 g / L under ambient conditions, then lithium bicarbonate remains in solution and a high A / O CO2 stripping scenario will occur. When aqueous lithium concentrations are above approximately 9 g / L, then the solution is saturated and the additional lithium precipitates out as lithium carbonate as described in the low A / O CO2 stripping condition. In such embodiments, the maximum lithium concentration in the loaded organic phase is taken to be 3 g / L and the aqueous phase is taken to be deionized water. Therefore, a “low A / O” regime as described herein is lower than 3: 1, and a “high A / O” regime as described herein is greater than or equal to 3 : 1.

[0044] Referring to FIG. 1, a process flow diagram in accordance with embodiments disclosed herein is shown. This process may be used to recover lithium from a solution, with the production of lithium carbonate through an essential step named low aqueous to organic volume ratio (A / O) CO2 stripping.

[0045] Embodiments disclosed herein are directed to a process that can be used to extract and purify lithium from a solution that contains lithium, with the production of battery -grade lithium carbonate through simple steps.

[0046] The solution that contains lithium is referred to as an aqueous phase (A) 100 in the process flow diagram FIG. 1. Those having ordinary skill in the art will appreciate that the lithium solution may originate from different sources, such as leachates of primary and secondary sources (e.g., spodumene, clays, lithium-ion batteries, ceramic glass), natural liquid lithium sources (e.g., salt lake brines, geotherm brines, produced water, acid mine drainage), wastewater (e.g., industrial wastewater, municipal waste water), combinations of these sources, and lithium-containing streams from lithium recovery processes.

[0047] The aqueous phase (A) 100 may first undergo a pretreatment step 102 to remove undesired constituents for downstream processing. The specific undesired constituents may depend on a number of factors, such as the operating parameters and flowsheet design of the downstream processing. The undesired constituents may typically include, but are not limited to, iron, aluminum, copper, calcium, magnesium, and titanium. The undesired constituents may be removed through a single method or a combination of different methods. The methods that may be used include, but are not limited to, selective precipitation by adding a precipitant or adjusting the redox potential of the solution, selective adsorption by reacting with an efficient adsorbent, solvent extraction using extractants showing high affinity towards the undesired constituents.

[0048] An organic phase (O) 104 may be prepared by mixing a diluent and an extractant. The diluent serves as a solvent for the extractant and may include, but is not limited to, kerosene, n-hexane, and heptane. The extractant exhibits a higher affinity for lithium ions compared to contaminants. Those having ordinary skill in the art will appreciate that different types of extractant are available for the extraction of lithium, which can be classified into acidic extractants (e.g., di-(2-ethylhexyl) phosphoric acid (D2EHPA)), neutral extractants (e.g., tri-n-butyl phosphate (TBP)), amines and quaternary ammonium compounds (e.g., tricaprylmethylammonium chloride (Aliquat 336)), ionic liquids, and synergistic solvent extraction systems. Those having ordinary skill in the art will also appreciate that in addition to the diluent and extractant, some other chemicals, such as phase modifiers, stabilizers, surfactants, and / or anti-foaming agents, may be added to the organic phase to enhance its performance of lithium extraction.

[0049] The organic phase 104 may require pretreatment 106 to make it suitable for lithium extraction, with the specific pretreatment method depending on the extractant utilized. For instance, when an acidic extractant is used, the organic phase may react with a sodium hydroxide (NaOH) or an ammonia solution to neutralize the extractant. During the reaction process, hydrogen ions (H+) in the acidic functional groups of the extractant are replaced with sodium ions (Na+). Na+ions in the neutralized extractant are more easily replaced by lithium ions (Li+) than H+. Consequently, Li+in the aqueous phase can be more easily extracted into the organic phase.

[0050] Following the pretreatment of both the aqueous phase 102 and the organic phase106, they are combined in a reactor to facilitate the extraction 108 of lithium ions from the aqueous phase into the organic phase. To achieve the desired purity and extraction efficiency, the extraction process may involve multiple extraction stages, and the extraction flowsheet may be configured in various ways, such as counter-current, cocurrent, and a combination of both. Those having ordinary skill in the art will appreciate that different types of reactors, such as mixer-settlers and centrifugal extractors, can be utilized for this step. After extraction, an organic phase loaded with lithium and possibly some impurities, as well as an aqueous phase depleted in lithium, are obtained. The aqueous phase depleted in lithium is referred to as raffinate 110 in the process flow diagram shown in FIG. 1.

[0051] The loaded organic phase obtained from the extraction step 108 may contain some impurities, such as sodium and potassium ions. These impurities may report to the final lithium carbonate product, reducing its quality. Consequently, the loaded organic phase may undergo a scrubbing step 112 to eliminate these undesired constituents. In this step, a scrubbing solution 114, such as deionized water, a weak acid solution, or a weak base solution, is mixed with the loaded organic phase in a reactor. To achieve the desired purity and scrubbing efficiency, the scrubbing process may involve multiple scrubbing stages, and the scrubbing flowsheet may be configured in various ways, such as counter-current, co-current, and a combination of both. Those having ordinary skill in the art will appreciate that different types of reactors, such as mixer- settlers and centrifugal extractors, can be utilized for this step. Those having ordinary skill in the art will also appreciate that the scrubbing step is optional and is contingent upon the concentration and type of impurities present in theloaded organic phase. After scrubbing, an organic phase 116 loaded with lithium but containing minimal impurities may be obtained, which will be further processed as discussed next.

[0052] Embodiments disclosed herein are directed to a method, low A / O CO2 stripping 118 using a multiphase dispersion contact reaction, for directly producing battery - grade lithium carbonate from the loaded organic phase after extraction 108 and / or scrubbing 112, using carbon dioxide (CO2) as a cost-effective and green reagent. In one aspect, the method disclosed herein comprises mixing the loaded organic phase with an aqueous solution at a relatively low aqueous to organic phase (A / O) volume ratio. A / O represents the volumetric ratio of the aqueous phase to the organic phase. Higher A / O ratios represent more aqueous phase, while lower A / O ratios represent less aqueous phase.

[0053] Assuming lithium concentration in the organic phase is fixed, the concentration of lithium in the aqueous phase after stripping is determined by A / O ratio. Higher A / O ratios represent lower lithium concentrations, while lower A / O ratios represent higher lithium concentrations. Whether lithium carbonate precipitates form in the aqueous phase is dependent on the concentration of lithium in the aqueous phase. If the lithium concentration is below 9 g / L, lithium exists as lithium bicarbonate in the aqueous phase. When the concentration rises beyond 9 g / L, the excessive lithium carbonate will become oversaturated, leading to the formation of lithium carbonate until lithium concentration in the aqueous phase drops below 9 g / L.

[0054] The aqueous solution may include, but is not limited to, deionized water and an under-saturated or saturated lithium carbonate solution. In one or more embodiments, CO2 gas in the form of microbubbles on the order of 100 pm in diameter may be injected into a liquid stream of loaded organic liquid phase and aqueous stripping solution. The shearing forces encountered furthermore divide the liquid stream into microdroplets on the order of 100 pm in diameter. The large interfacial contact area between the CO2 and liquid phase significantly accelerates the stripping reaction compared to conventional stirred reactors. A multiphase dispersion contact reactor can be operated at ambient temperature and pressure to accelerate reaction times to around the 1 -minute scale. In another aspect, during the mixing of the loaded organic phase and the aqueous solution, CO2 is injected into the mixture from a CO2 source,which includes, but is not limited to, a pressurized CO2 cylinder, a CO2 generator, air, or a gaseous mixture containing CO2. In the further aspect, the mixing may occur under controlled conditions, such as temperature in the range of 5-70 °C, pressure in the range of 0-40 bar, reaction duration in the range of 1 minute to 6 h.

[0055] After low A / O CO2 stripping 118 using a multiphase dispersion contact reaction, lithium ions in the loaded organic phase precipitate out as lithium carbonate. The resulting suspension may undergo solid / liquid separation to separate liquids from solids. Any solid / liquid separation methods, such as filter press, vacuum filter, or belt filter, may be used for this purpose. The resulting solid is subjected to further processing as discussed next, while the liquid is sent to A / O phase separation 122 to separate the organic phase and the aqueous solution. Those having ordinary skill in the art will appreciate that different types of reactors, such as mixer-settlers and centrifugal extractors, can be utilized for this step. Those having ordinary skill in the art will also appreciate that any equipment and containers capable of phase separation based on density differences can be used for this step.

[0056] The solid lithium carbonate product obtained from solid / liquid separation 120 may contain a certain amount of organic compounds, referred to as oil in the following disclosure and claims. The oil may originate from the organic phase during low A / O CO2 stripping 118 using a multiphase dispersion contact reaction, due to the inefficiency of solid / liquid separation 120 in removing surface liquid and liquid entrapped within solid particles. The presence of oil in the lithium carbonate product may prevent it from meeting battery-grade standards. Therefore, the solid lithium carbonate undergoes a solid de-oiling step 124 to remove the oil. Embodiments disclosed herein are directed to various methods that may be used to achieve the objective. In one aspect, the lithium carbonate may be washed with a volatile solvent capable of solvating the oil, which includes, but is not limited to, alcohol, heptane, and acetone. After several washes, any remaining solvent in the lithium carbonate can be removed using an appropriate approach, such as thermal drying or low temperature drying. In another aspect, the remaining solvent may be used by contacting the solid with a supercritical fluid, such as supercritical CO2 or supercritical water. Those having ordinary skill in the art will appreciate that various other methods for removing organic compounds from solid particles could potentially be employed in this step.

[0057] After the solid de-oiling step 124, the lithium carbonate may be dried, depending on the specific solid de-oiling method used, leading to a final battery-grade lithium carbonate product 126. Those having ordinary skill in the art will appreciate that various drying equipment can be used to achieve this objective, such as rotary dryers, fluidized bed dryers, vacuum dryers, and drum dryers.

[0058] Referring to FIG. 2, a process flow diagram in accordance with embodiments disclosed herein is shown. This process may be used to recover lithium from a solution, starting with the production of dissolved lithium bicarbonate followed by lithium carbonate.

[0059] Embodiments disclosed herein are directed to a process that can be used to extract and purify lithium from a solution that contains lithium, with the production of dissolved lithium bicarbonate first followed by lithium carbonate.

[0060] The solution that contains lithium is referred to as an aqueous phase (A) 200 in the process flow diagram FIG. 2. Those having ordinary skill in the art will appreciate that the lithium solution may originate from different sources, such as leachates of primary and secondary sources (e.g., spodumene, clays, lithium-ion batteries, ceramics glass), natural liquid lithium sources (e.g., salt lake brines, geotherm brines, produced water, acid mine drainage), wastewater (e.g., industrial wastewater, municipal waste water), combinations of these sources, and lithium-containing streams from lithium recovery processes.

[0061] The aqueous phase (A) 200 may first undergo a pretreatment step 202 to remove undesired constituents for downstream processing. The specific undesired constituents may depend on a number of factors, such as the operating parameters and flowsheet design of the downstream processing. The undesired constituents may typically include, but are not limited to, iron, aluminum, copper, calcium, magnesium, and titanium. The undesired constituents may be removed through a single method or a combination of different methods. The methods that may be used include, but are not limited to, selective precipitation by adding a precipitant or adjusting the redox potential of the solution, selective adsorption by reacting with an efficient adsorbent, solvent extraction using extractants showing high affinity towards the undesired constituents.

[0062] An organic phase (O) 204 may be prepared by mixing a diluent and an extractant. The diluent serves as a solvent for the extractant and may include, but is not limited to, kerosene, n-hexane, and heptane. The extractant exhibits a higher affinity for lithium ions compared to contaminants. Those having ordinary skill in the art will appreciate that different types of extractant are available for the extraction of lithium, which can be classified into acidic extractants (e.g., di-(2-ethylhexyl) phosphoric acid (D2EHPA)), neutral extractants (e.g., tri-n-butyl phosphate (TBP)), amines and quaternary ammonium compounds (e.g., tricaprylmethylammonium chloride (Aliquat 336)), ionic liquids, and synergistic solvent extraction systems. Those having ordinary skill in the art will also appreciate that in addition to the diluent and extractant, some other chemicals, such as phase modifiers, stabilizers, surfactants, and anti-foaming agents, may be added to the organic phase to enhance its performance of lithium extraction.

[0063] Following the pretreatment of both the aqueous phase 202 and the organic phase 206, they are combined in a reactor to facilitate the extraction 208 of lithium ions from the aqueous phase into the organic phase. To achieve the desired purity and extraction efficiency, the extraction process may involve multiple extraction stages, and the extraction flowsheet may be configured in various ways, such as counter-current, cocurrent, and a combination of both. Those having ordinary skill in the art will appreciate that different types of reactors, such as mixer-settlers and centrifugal extractors, can be utilized for this step. After extraction, an organic phase loaded with lithium and possibly some impurities, as well as an aqueous phase depleted in lithium, are obtained. The aqueous phase depleted in lithium is referred to as raffinate 210 in the process flow diagram shown in FIG. 2.

[0064] The loaded organic phase obtained from the extraction step 208 may contain some impurities, such as sodium and potassium ions. These impurities may report to the final lithium carbonate product, reducing its quality. Consequently, the loaded organic phase may undergo a scrubbing step 212 to eliminate these undesired constituents. In this step, a scrubbing solution 214, such as deionized water, a weak acid solution, or a weak base solution, is mixed with the loaded organic phase in a reactor. To achieve the desired purity and scrubbing efficiency, the scrubbing process may involve multiple scrubbing stages, and the scrubbing flowsheet may beconfigured in various ways, such as counter-current, co-current, and a combination of both. Those having ordinary skill in the art will appreciate that different types of reactors, such as mixer- settlers and centrifugal extractors, can be utilized for this step. Those having ordinary skill in the art will also appreciate that the scrubbing step is optional and is contingent upon the concentration and type of impurities present in the loaded organic phase. After scrubbing, an organic phase 216 loaded with lithium but containing minimal impurities may be obtained, which will be further processed as discussed next.

[0065] Embodiments disclosed herein are directed to a method, high A / O CO2 stripping 218, for transferring lithium from the loaded organic phase after extraction 208 and / or scrubbing 212 to an aqueous solution by forming soluble lithium bicarbonate. Carbon dioxide (CO2) is used in this step as a cost-effective and green reagent to facilitate the transfer of lithium and the formation of lithium bicarbonate. In one aspect, the method disclosed herein comprises mixing the loaded organic phase with an aqueous solution at a relatively high aqueous to organic (A / O) phase volume ratio. The aqueous solution may include, but is not limited to, deionized water and an under- saturated or saturated lithium bicarbonate solution. In another aspect, during the mixing of the loaded organic phase and the aqueous solution, CO2 is injected into the mixture from a CO2 source, which includes, but is not limited to, a pressurized CO2 cylinder, a CO2 generator, air, or a gaseous mixture containing CO2. In the further aspect, the mixing may occur under controlled conditions, such as temperature in the range of 5-80 °C, pressure in the range of 0-200 bar, reaction duration in the range of 1 minute to 6h.

[0066] After the high A / O CO2 stripping 218, the aqueous solution and the organic phase may subject to phase separation 220 to separate them. Those having ordinary skill in the art will appreciate that different types of reactors, such as mixer-settlers and centrifugal extractors, can be utilized for this step. Those having ordinary skill in the art will also appreciate that any equipment and containers capable of phase separation based on density differences can be used for this step. After phase separation, the organic phase may be reused for extraction 208, while the aqueous solution may be further processed as discussed next.

[0067] The aqueous phase after phase separation 220 may retain some oil due to the inefficiency of the phase separation and / or the presence of water-soluble oil.Consequently, a liquid de-oiling step 222 may be conducted to remove any remaining oil from the aqueous solution. Otherwise, the remaining oil may end up in the final lithium carbonate product and compromise its quality. To achieve the target removal efficiency, this step can be completed through a single approach or a combination of different approaches. In one aspect, adsorption with a highly efficient adsorbent, such as activated carbon, may be utilized to process the aqueous phase for oil removal. Those having ordinary skill in the art will appreciate that any oil removal approaches, such as flocculation, membrane filtration, and / or electrocoagulation, may be used to achieve the objective in this step. Importantly, the selected de-oiling approach should not introduce any contaminants into the aqueous phase.

[0068] After the liquid de-oiling step 222, the contaminants in the aqueous solution are effectively eliminated, leading to a high-purity lithium bicarbonate solution. The solution is then fed to mechanical vapor recompression (MVR) 224 to evaporate water and form lithium carbonate precipitate 226. Alternatively, the lithium bicarbonate solution may be reacted with CaO and other bases of similar properties to convert lithium bicarbonate into lithium hydroxide and solid precipitates of the base metal (e.g., CaCCh if CaO) is used. Then, MVR may be used to obtain lithium hydroxide precipitate from the lithium hydroxide solution. The precipitate meets the batterygrade standards. Those having ordinary skill in the art will appreciate that any other methods used for water evaporation and salt crystallization, such as thermal vapor compression, multiple effect evaporation, membrane distillation, vacuum evaporation, and / or solar evaporation, may be used in this step to produce batterygrade lithium carbonate.

[0069] Referring to FIG. 3, a schematic diagram for producing lithium carbonate from an organic phase loaded with lithium after solvent extraction is shown.

[0070] Embodiments disclosed herein are directed to a system that can be used to produce lithium carbonate solid product from an organic phase loaded with lithium. The system is based on the low A / O stripping technology and may be used to complete the processing steps after the solvent extraction step as depicted in the process flow diagram in FIG. 1. It offers the advantages of low carbon dioxide consumption and rapid lithium precipitation kinetics through the use of a suspension recirculation unit and a carbon dioxide recirculation unit.

[0071] As shown in FIG. 3, an organic phase loaded with lithium 300 is introduced into a tank reactor 302, which is equipped with a recirculating unit driven by a recirculating pump 304. A multiphase dispersion contact reactor 306, operating with a mechanism similar to a Venturi tube, is installed in the recirculating circuit. The recirculating pump 304 moves the suspension, including the organic phase 300 and an aqueous solution 308 in the tank, through the recirculating circuit at a high flow velocity. In one or more embodiments, this causes pressure changes in the multiphase dispersion contact reactor 306, creating high-pressure and low-pressure zones. A gas line 310 introduces carbon dioxide to multiphase dispersion contact reactor 306. The pressure changes and extensive shearing in multiphase dispersion contact reactor 306 generate gaseous microbubbles and liquid microdroplets with diameters in the range of 10 nm to 1000 pm, such as a lower limit of any of 10 nm, 50 nm, 100 nm, 500 nm, 1 pm, 10 pm, 50, pm, or 100 pm to an upper limit of any of 100 pm, 250 pm, 500 pm, 750 pm, or 1000 pm, significantly increasing the interfacial area between the liquid and gaseous phases and greatly enhancing the mass transfer rate. Additionally, in one or more embodiments the turbulent flow in multiphase dispersion contact reactor 306 further enhances the mass transfer rate. In the presence of carbon dioxide and the aqueous solution, and facilitated by the high mass transfer rate, lithium in the organic phase precipitates as solid lithium carbonate.

[0072] In one or more embodiments, the method and systems disclosed herein include a multiphase dispersion contact reactor fluidly connected to the reaction tank that includes a gas-phase input stream pressurized using one or more of the following systems: mechanical compression, including positive displacement compressors (piston, reciprocating, rotary screw, rotary vane, scroll), centrifugal compressors, axial compressors, and diaphragm compressors; dynamic flow mechanisms such as venturi nozzles or jet injectors (steam or air); liquid displacement or piston-based systems, including hydraulic pressurization, syringe pumps, or piston pumps; thermal methods, including heating of confined gases or phase-change vapor compression; external confinement or pressure sources, such as overburden compression, hydrostatic pressure, or membrane-based compression; inertial or shock compression, including shock wave or isentropic (adiabatic) compression; confined-space chemical or biological gas generation, including sealed-volume generation or electrochemicalproduction; process-specific mechanisms, including valve backpressure, vacuum systems, cascade compression, or supercritical fluid compression, where the flow rate of said gas-phase stream is regulated accordingly; the liquid-phase input stream is pressurized using one or more of the following systems: mechanical pumps, including positive displacement pumps (piston, plunger, diaphragm, gear, screw, peristaltic), centrifugal, axial flow, or rotary vane pumps; hydraulic amplification, including hydraulic intensifiers and gas-charged accumulators; gas-over-liquid systems, including pressurized vessels with gas headspace or gas-driven syringe pumps; external mechanical force on a liquid-containing chamber, such as membrane compression or flexible bladders; thermal expansion within a confined liquid volume; gravitational pressure (e.g., elevation-driven head pressure); dynamic or inertial effects, such as water hammer, centrifugal acceleration, or shock-induced pressure; backpressure or flow restriction mechanisms; capillary or interfacial tension-driven systems, including osmotic effects; natural or geologic pressurization, including deep- sea or hydrothermal systems, wherein the flow rate of said liquid-phase stream is similarly regulated; shear forces are generated within the reactor via one or more of mechanical shear (e.g., impellers, high-shear mixers, colloid mills, high-pressure homogenizers); hydrodynamic shear (e.g., venturi tubes, orifice nozzles, static mixers, junctions, coaxial injectors); acoustic or ultrasonic shear (e.g., ultrasonic horns, acoustic cavitation); electric field-induced shear (e.g., electrospray, dielectric barrier discharge); thermally induced interfacial shear (e.g., Marangoni effect); constrictionbased shear (e.g., membrane emulsification, microfluidic devices, porous media); turbulence-induced shear (e.g., jet breakup, vortex shear); wall or boundary layer effects; said shear forces disperse the gas-phase stream into microbubbles and the liquid-phase stream into microdroplets, each ranging in size from approximately 10 nm to 1000 pm; and the reactor is configured to maintain contact between said dispersed gas and liquid phases in a mixing zone, enabling physical, chemical, and physicochemical interactions, including but not limited to: gas dissolution, redox reactions, acid-base neutralization, or interfacial catalysis; mass transfer, coalescence, impaction, differential settling or rising, and shear-induced effects; interfacial adsorption, surface tension modulation, solute partitioning, reactive transport, and charge-based interactions; wherein a product of said interactions is discharged through one or more outlet ports.

[0073] Carbon dioxide is also recirculated in the system. As shown in FIG.3, carbon dioxide exiting the tank reactor 302 is collected through a carbon dioxide off-gas line 312. Using a compressor 314, the carbon dioxide is re-pressurized and stored in a buffering tank 316, which is also connected to a liquid carbon dioxide cylinder 318. When the carbon dioxide level is insufficient for the reaction in the tank reactor 302, carbon dioxide from the cylinder 318 is introduced into the buffering tank 316 through a line and regulated by high-pressure (HP) and low-pressure (LP) regulators 320. The carbon dioxide storage tank 316 is connected to the multiphase dispersion contact reactor 306 in the suspension recirculating unit through line 310, with the flow adjusted by a regulator 322.

[0074] After reaction in the tank reactor 302, the suspension at the bottom is introduced to a filter press 324 for solid / liquid separation, resulting in a solid and a liquid that contains the aqueous solution and the organic phase. The liquid is then directed to a phase separator 326 for phase separation. After that, the organic phase is regarded as a regenerated organic phase 328 and can be reused for solvent extraction, while the aqueous phase 308 contains low lithium concentration and is redirected to the tank reactor 302 to serve as an aqueous medium for the reaction in the tank. The solid is directed to solid de-oil 330 to remove any remaining oil. Finally, this process culminates in the production of a high-quality battery-grade lithium carbonate product 332.

[0075] Referring to FIG. 4, another schematic diagram for producing lithium carbonate from an organic phase loaded with lithium after solvent extraction is shown.

[0076] Embodiments disclosed herein are directed to another system that can be used to produce lithium carbonate product from an organic phase loaded with lithium 400. The system is based on the high A / O stripping technical and may be used to complete the processing steps after the solvent extraction step as depicted in the process flow diagram in FIG. 2. Unlike the system depicted in FIG. 3, the system shown in FIG. 4 first transfers lithium from the organic phase 400 to an aqueous solution as soluble lithium bicarbonate, rather than directly precipitating it as solid lithium carbonate. Therefore, the initial part of the system shown in FIG. 4 is similar to that of the system shown in FIG. 3, but the latter part differs.

[0077] Similar to the system shown in FIG. 3, the initial part of the system shown in FIG. 4 includes a tank reactor 402 equipped with a suspension recirculation unit that includes pump 404 and multiphase dispersion contact reactor 406 and a carbon dioxide recirculating unit 412-422. Notably, the suspension recirculation unit in FIG. 4, like the one in FIG. 3, includes a multiphase dispersion contact reactor 406 that operates similarly to a Venturi tube. This multiphase dispersion contact reactor generates carbon dioxide microbubbles and liquid microdroplets with diameters in the range of 10 nm to 1000 pm, such as a lower limit of any of 10 nm, 50 nm, 100 nm, 500 nm, 1 pm, 10 pm, 50, pm, or 100 pm to an upper limit of any of 100 pm, 250 pm, 500 pm, 750 pm, or 1000 pm, which undergo strong turbulent flows, thereby enhancing the mass transfer rate. By controlling the operating conditions in the multiphase dispersion contact reactor 406, such as the A / O ratio, lithium loaded in the organic phase is transferred to the aqueous phase by forming soluble lithium bicarbonate.

[0078] After reaction in the tank reactor 402, the suspension at the bottom is directed to a phase separator to separate the organic and aqueous phases. The resulting organic phase 426 can be reused for solvent extraction. The resulting lithium bicarbonate solution is directed to a solution de-oiling step 428 to remove any residual oil. Following de-oiling, the lithium bicarbonate solution proceeds to a lithium bicarbonate decomposition reactor 430, where it decomposes into solid lithium carbonate and carbon dioxide off gas. The off gas is collected and re-pressurized through compressor 414, while the resulting suspension is fed to a filter press 432 to separate solids from liquids. The resulting solid is the final battery-grade lithium carbonate product 434, while the liquid 408 is reused as an aqueous solution medium for the reaction in the tank reactor 402.

[0079] Referring to FIG. 5, a further schematic diagram for producing lithium carbonate from an organic phase loaded with lithium after solvent extraction is shown.

[0080] Embodiments disclosed herein are directed to a further system that can be used to produce lithium carbonate product from an organic phase loaded with lithium. The system is based on the high A / O stripping technical and may be used to complete the processing steps after the solvent extraction step as depicted in the process flowdiagram in FIG. 2. Unlike the system depicted in FIG. 3, the system shown in FIG. 5 first transfers lithium from the organic phase to an aqueous solution as soluble lithium bicarbonate, rather than directly precipitating it as solid lithium carbonate. Additionally, unlike the system depicted in FIG. 4, the system shown in FIG. 5 uses a high-pressure reactor with a mixing system to accelerate the mass transfer rate. Therefore, the system shown in FIG. 5 is similar to that in FIG. 4 except the part for transferring lithium from the organic phase to an aqueous solution.

[0081] As shown in FIG. 5, a lithium-loaded organic phase 500 and an aqueous solution 528 with low lithium content, coming from the end part of the system, are directed into a solution compressor 502. The compressed solution is then directed into a high- pressure reactor 504. Carbon dioxide, regulated by a regulator 506, is also directed into the reactor from a buffering tank 508. The reactor 504 may be equipped with a mixing mechanism to ensure adequate contact among the three phases: the organic phase, the aqueous solution, and the carbon dioxide.

[0082] After reaction in the reactor 504, the organic / aqueous mixed solution is directed to a phase separator 512 through a solution pressure relief 510. After phase separation, the organic phase 514 can be reused for solvent extraction, while the aqueous solution 516 is directed to a solution de-oiling step 518 to remove any residual oil. Following this, the aqueous solution is directed into a reactor 520, where the lithium bicarbonate in the solution is decomposed into solid lithium carbonate and carbon dioxide off gas. The off gas is collected and re-pressurized through compressor 522, while the resulting suspension is fed to a filter press 524 to separate solids from liquids. The resulting solid is the final battery-grade lithium carbonate product 526, while the liquid 528 is reused as an aqueous solution medium for the reaction in the tank reactor 504. In addition to the recycled carbon dioxide from the decomposition reactor 520, carbon dioxide may also come from another source 530 regulated by high-pressure and low-pressure regulators 532.

[0083] Table 1. Example chemical compositions of the Li2CO3 product produced using the disclosed technology.

[0084] In accordance with the purpose(s) of the disclosure, as embodied and broadly described herein, the disclosure relates to two processing routes and three processing diagrams for producing battery-grade lithium carbonate from lithium-containing solutions.

[0085] In some aspects, the techniques described herein relate to a process for producing lithium carbonate from aqueous solutions feedstocks, including: pretreating an aqueous solution containing lithium to remove undesired impurities for downstream processing; pretreating an organic phase to improve its efficiency in lithium extraction; extracting lithium from the pretreated aqueous solution to the pretreated organic phase by mixing the two phases, resulting in a lithium-loaded organic phase; scrubbing the lithium-loaded organic phase to remove co-extracted contaminants, yielding a high-purity lithium-loaded organic phase; conducting low A / O CO2 stripping on the high-purity lithium-loaded organic phase by mixing with carbon dioxide and another aqueous solution to produce solid lithium carbonate; performing solid / liquid separation on the resulting suspension to separate the solid from the liquid; directing the solid to a solid de-oiling step to remove any residual oil and obtain battery-grade lithium carbonate; directing the liquid to a phase separator to separate the organic phase from the aqueous solution.

[0086] In some aspects, the techniques described herein relate to a method, wherein the aqueous solution may come from different sources, which include, but are not limited to leachates of primary and secondary sources, natural liquid lithium sources, wastewater, and lithium-containing streams from lithium recovery processes.

[0087] In some aspects, the techniques described herein relate to a method, wherein various methods, such as selective precipitation, pH adjustment, selective adsorption, and solvent extraction, may be used individually or in combination to remove undesired contaminants from the aqueous solution.

[0088] In some aspects, the techniques described herein relate to a method, wherein the organic phase may be pretreated by reacting with acids or bases.

[0089] In some aspects, the techniques described herein relate to a method, wherein mixing of the aqueous solution and the organic phase can occur in various stages, which may be configured in various ways, such as counter-current, co-current, and a combination of both.

[0090] In some aspects, the techniques described herein relate to a method, wherein the use of scrubbing to remove co-extracted contaminants from the lithium-loaded organic phase is optional.

[0091] In some aspects, the techniques described herein relate to a method, wherein the low A / O CO2 stripping may occur under certain conditions.

[0092] In some aspects, the techniques described herein relate to a method, wherein the carbon dioxide may come from different sources, such as a pressurized CO2 cylinder, a CO2 generator, air, or a gaseous mixture containing CO2.

[0093] In some aspects, the techniques described herein relate to a method, wherein various methods, such as washing with a volatile solvent and treating with supercritical fluids, may be used individually or in combination to remove oil.

[0094] In some aspects, the techniques described herein relate to another process for producing lithium carbonate from aqueous solutions feedstocks, including: pretreating an aqueous solution containing lithium to remove undesired impurities for downstream processing; pretreating an organic phase to improve its efficiency in lithium extraction; extracting lithium from the pretreated aqueous solution to the pretreated organic phase by mixing the two phases, resulting in a lithium-loaded organic phase; scrubbing the lithium-loaded organic phase to remove co-extracted contaminants, yielding a high-purity lithium-loaded organic phase; conducting high A / O CO2 stripping on the high-purity lithium-loaded organic phase by mixing with carbon dioxide and another aqueous solution; directing the resulting mixed solution to a phase separator to separate the organic phase from the aqueous solution; directing the aqueous solution to a liquid de-oiling step to remove any residual oil; processingthe aqueous solution after de-oiling through mechanical vapor recompression (MVR) to obtain battery -grade lithium carbonate.

[0095] In some aspects, the techniques described herein relate to a method, wherein the high A / O CO2 stripping may occur under certain conditions.

[0096] In some aspects, the techniques described herein relate to a system for directly producing solid lithium carbonate from a lithium-loaded organic phase, including: a reactor equipped with a suspension recirculation system to enhance the mass transfer rate for the reaction; a carbon dioxide recirculation system to enhance carbon dioxide utilization; solid / liquid separators to separate the solid from the liquid; phase separators to separate the organic phase and the aqueous phase; a solid de-oiling system to remove oil from the solid lithium carbonate; auxiliary parts, such as regulators, pipes, and pumps, for material transfer and flow.

[0097] In some aspects, the techniques described herein relate to a system, wherein the multiphase dispersion contact reactor may take the form of venturi tubes or similar apparatuses installed in the recirculation system to enhance the reaction efficiency.

[0098] In some aspects, the techniques described herein relate to a system for producing a lithium bicarbonate-rich solution, followed by solid lithium carbonate, from a lithium-loaded organic phase, including: a reactor equipped with a suspension recirculation system to enhance the mass transfer rate for the reaction; a carbon dioxide recirculation system to enhance carbon dioxide utilization; phase separators to separate the organic phase and the aqueous phase; a liquid de-oiling system to remove oil from the aqueous solution; a decomposition reactor to decompose lithium bicarbonate in the solution into solid lithium bicarbonate and gaseous carbon dioxide; solid / liquid separators to separate the solid from the liquid; auxiliary parts, such as regulators, pipes, and pumps, for material transfer and flow.

[0099] In some aspects, the techniques described herein relate to a system, wherein the reactor equipped with a suspension recirculation system may be replaced by a high- pressure reactor equipped with pressurization and depressurization systems.

Claims

CLAIMSWhat is claimed is:

1. A method for producing lithium carbonate from aqueous solutions feedstocks, comprising: extracting lithium from an aqueous solution with an organic phase to form a lithium loaded organic phase; stripping the lithium loaded organic phase formed from extracting lithium, wherein the stripping is performed at a temperature ranging from 5°C to 80°C and with a solution comprising dissolved lithium carbonate or lithium bicarbonate; de-oiling a solid lithium carbonate or a stripped aqueous lithium bicarbonate phase formed from stripping; and processing a solid formed from de-oiling the solid lithium carbonate or a liquid formed from de-oiling the liquid lithium bicarbonate to obtain a battery -grade lithium carbonate.

2. The method of claim 1, wherein before extracting lithium from an aqueous solution, the method further comprises: pretreating the aqueous solution to remove impurities; and pretreating an organic phase to improve its efficiency in lithium extraction.

3. The method of claim 1 or 2, wherein the extracting lithium from an aqueous solution comprises: mixing the aqueous solution with the organic phase; and scrubbing the lithium loaded organic phase from mixing the aqueous solution with the organic phase, with a scrubbing solution to remove co-extracted contaminants.

4. The method of any one of claims 1 to 3, wherein the stripping the lithium-loaded organic phase formed from extracting lithium comprises: mixing the lithium loaded organic phase with the solution comprising dissolved lithium carbonate to form a solution; injecting the solution with carbon dioxide to form a suspension; and filtering the suspension to form the solid lithium carbonate.

5. The method of claim 4, further comprising: directing a liquid from the filtering the suspension to a phase separator to separate the liquid into an organic phase and an aqueous solution.

6. The method of any one of the preceding claims, wherein the processing the solid formed from de-oiling comprises: washing the solid with a solvent capable of solvating oil; and subsequently drying the solid to provide the battery-grade lithium carbonate.

7. The method of any one of claims 1 to 3, wherein the stripping the lithium-loaded organic phase from extracting lithium comprises: mixing the loaded organic phase with the solution comprising dissolved lithium bicarbonate to form a solution; injecting the solution with carbon dioxide to form a solution comprising a stripped organic phase and a stripped aqueous lithium bicarbonate phase; and separating the stripped organic phase from the stripped aqueous lithium bicarbonate phase.

8. The method of claim 7, wherein after the de-oiling the lithium bicarbonate, the method further comprises: concentrating a high-purity lithium bicarbonate formed from de-oiling the stripped aqueous lithium bicarbonate phase; and precipitating the battery-grade lithium carbonate.

9. The method of any one of the preceding claims, wherein the aqueous solution is derived from leachates of primary and secondary sources, natural liquid lithium sources, wastewater, and lithium-containing streams from lithium recovery processes or combinations thereof.

10. The method of any one of the preceding claims, wherein the extracting lithium from the aqueous solution occurs in multiple stages, and comprises counter-current flows, co-current flows, or a combination of both.

11. The method of any one of the preceding claims, wherein the carbon dioxide is provided from a pressurized CO2 cylinder, a CO2 generator, air, a gaseous mixture containing CO2, or combinations thereof.

12. A system for stripping loaded lithium organic phases to produce lithium carbonate, the system comprising: a reaction tank configured to i) receive a lithium loaded organic stream from a solvent extraction system and a solution comprising dissolved lithium carbonate or lithium bicarbonate to form a combined liquid-phase stream and ii) discharge carbon dioxide off gas; a multiphase dispersion contact reactor fluidly connected to the reaction tank; a suspension recirculation system configured to flow the combined liquid-phase stream from the reactor to the multiphase dispersion contact reactor; a carbon dioxide recirculation system configured i) to introduce a gas-phase stream comprising carbon dioxide to the multiphase dispersion contact reactor and ii) receive carbon dioxide off gas; and a de-oiling system to remove oil from a solid lithium carbonate or a stripped aqueous bicarbonate phase formed from stripping.

13. The system of claim 12, further comprising solid / liquid separators and / or liquid phase separators to separate the suspension formed in the reactor and to form the solid lithium carbonate or the stripped aqueous lithium bicarbonate phase.

14. The system of claim 12 or 13, further comprising a decomposition reactor to decompose lithium bicarbonate in the solution into solid lithium bicarbonate and gaseous.

15. The system of any one of claims 12 to 14, wherein the multiphase dispersion contact reactor comprises Venturi tubes.

16. The system of any one of claims 12 to 15, wherein the reactor is a high-pressure reactor equipped with pressurization and depressurization systems.

17. The system of any one of claims 12 to 16, wherein the stripped aqueous bicarbonate phase comprises lithium or sodium.

8. The system of any one of claims 12 to 17, wherein the multiphase dispersion contact reactor is configured to: 1) pressurize each of the gas-phase stream and the combined liquid-phase stream, 2) generate shear forces therein such that the shear forces disperse the gas-phase stream into microbubbles and the liquid-phase stream into microdroplets, and 3) maintain contact between the dispersed microbubbles and microdroplets in a mixing zone to enable physical, chemical, and / or physicochemical interactions therebetween, wherein a product of the interactions is discharged through one or more outlet ports in the multiphase dispersion contact reactor.

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