Process for producing battery-grade lithium hydroxide monohydrate with low carbonate content

Abstract

A process for producing battery-grade lithium hydroxide monohydrate with a low carbonate content, comprising: forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate from a lithium feed containing impurities; removing at least some lithium carbonate from the solution; crystallizing the lithium hydroxide monohydrate; and separating the crystallized lithium hydroxide monohydrate from the solution.

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 581,920, filed on 11 September 2023, which is incorporated herein by reference in its entirety.

[0002] This invention relates to a process for producing battery-grade lithium hydroxide monohydrate with a low carbonate content. [Background technology]

[0003] Lithium-ion batteries are rechargeable batteries commonly used in a wide range of electronic devices, from smartphones and laptops to electric vehicles and renewable energy storage systems. In lithium-ion batteries, lithium ions move between the positive and negative electrodes (cathode and anode) during the charging and discharging process. Lithium hydroxide can be used as the cathode active material (CAM). The movement of lithium ions between the positive and negative electrodes is facilitated by the electrolyte. One type of electrolyte used is solid lithium sulfide. For lithium sulfide production (solid), it is preferable that the carbonate content in lithium hydroxide is as low as possible.

[0004] The presence of carbonates in lithium hydroxide can be harmful. Lower carbonate content can improve battery performance, safety, cycle life, efficiency, energy density, and manufacturing consistency. These factors can be crucial for the successful development and deployment of high-performance lithium-ion batteries in various applications.

[0005] Therefore, a process for efficiently producing lithium hydroxide monohydrate with a low carbonate content may be desirable. [Overview of the project]

[0006] Exemplary embodiments of a process for producing battery-grade lithium hydroxide monohydrate with a low carbonate content can substantially avoid one or more of the problems caused by the limitations and drawbacks of the relevant technology.

[0007] Additional features and advantages of the process described herein are described below, some of which may become apparent from the description or may be acquired through the implementation of this process. The objectives and other advantages of this process will be realized and achieved by the specification and claims described herein, as well as the structures specifically indicated in the accompanying drawings.

[0008] In some examples, a process for producing lithium hydroxide monohydrate may be provided, comprising: forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate; removing at least some lithium carbonate from the concentrated lithium hydroxide solution via a first solid-liquid separation step; crystallizing the lithium hydroxide monohydrate in the concentrated lithium hydroxide solution; and separating the crystallized lithium hydroxide monohydrate from the concentrated lithium hydroxide solution via a second solid-liquid separation step.

[0009] In some examples, forming a concentrated lithium hydroxide solution may involve supplying a lithium-containing feedstock.

[0010] In some examples, providing a lithium-containing supply may include providing a lithium hydroxide solution, which may be crude lithium hydroxide, technical grade lithium hydroxide, industrial grade lithium hydroxide, battery grade lithium hydroxide, primary grade lithium hydroxide, lithium hydroxide containing impurities, or any combination thereof.

[0011] In some examples, providing a lithium-containing supply may include providing lithium carbonate, which may be crude lithium carbonate, technical grade lithium carbonate, industrial grade lithium carbonate, primary grade lithium carbonate, battery grade lithium carbonate, impurity-containing lithium carbonate, or any combination thereof.

[0012] In some examples, this process may involve dissolving lithium carbonate to obtain a lithium hydroxide solution. In some examples, the dissolution may involve reacting lithium carbonate with an acid or alkaline earth hydroxide.

[0013] In some cases, the dissolution of lithium carbonate may involve reacting lithium carbonate with an acid, which may be sulfuric acid, thereby producing a lithium sulfate solution.

[0014] In some examples, the process may involve reacting a lithium sulfate solution with a hydroxide to form a lithium hydroxide solution. In some examples, the hydroxide may include sodium hydroxide, and the process may involve generating an aqueous sodium sulfate solution, performing cooling crystallization to crystallize the aqueous sodium sulfate solution to obtain Glauber's salt, and separating Glauber's salt from the lithium hydroxide solution via a third solid-liquid separation step to obtain a purified lithium hydroxide solution. In some examples, forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate may involve concentrating the purified lithium hydroxide solution. In some examples, concentrating the purified lithium hydroxide solution may involve an evaporation step.

[0015] In some examples, the hydroxide may include barium hydroxide, and the process may include producing solid barium sulfate and separating the solid barium sulfate from the lithium hydroxide solution via a second solid-liquid separation step to obtain a purified lithium hydroxide solution. In some examples, forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate may include concentrating the purified lithium hydroxide solution obtained from one or more of the above steps. In some examples, concentrating the purified lithium hydroxide solution may include an evaporation step.

[0016] In some examples, the dissolution of lithium carbonate may involve reacting lithium carbonate with an alkaline earth hydroxide to form a lithium hydroxide solution. In some examples, the alkaline earth hydroxide may include calcium hydroxide, and this process may involve reacting calcium hydroxide in the lithium hydroxide solution to form solid calcium carbonate and removing the solid calcium carbonate via a third solid-liquid separation. In some examples, this process may involve ion-exchange treatment of the previously provided or formed lithium hydroxide solution to obtain a purified lithium hydroxide solution. In some examples, forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate may involve concentrating the purified lithium hydroxide solution by an evaporation step.

[0017] In some examples, ion exchange to obtain a purified lithium hydroxide solution may involve contacting the lithium hydroxide solution with a first resin capable of removing carbonates, sulfates, or both, and then optionally contacting the lithium hydroxide solution with a second resin capable of removing calcium, magnesium, polyvalent cations, or a combination thereof.

[0018] In some examples, before crystallizing lithium hydroxide monohydrate, the process may include purifying the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate by removing at least some lithium carbonate by ion exchange, and then contacting the solution with a third resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof.

[0019] In some examples, the ion exchange for obtaining a purified lithium hydroxide solution may comprise a first ion exchange treatment that may include contacting the lithium hydroxide solution with a first resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof. In some examples, the present process may comprise concentrating the purified lithium hydroxide solution, contacting the concentrated lithium hydroxide solution with calcium hydroxide to react with the lithium carbonate present, forming calcium carbonate solids and an additional aqueous lithium hydroxide solution, and removing at least a portion of the formed calcium carbonate and residual lithium carbonate by a fourth solid-liquid separation. In some examples, the present process may comprise further purifying the lithium hydroxide solution by a second ion exchange treatment after the fourth solid-liquid separation, wherein the second ion exchange treatment comprises contacting the lithium hydroxide solution with a second resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof to obtain a purified lithium hydroxide solution, and concentrating the lithium hydroxide solution after this second ion exchange treatment by an evaporation step to form a concentrated lithium hydroxide solution that is saturated or nearly saturated with lithium hydroxide monohydrate.

[0020] In some examples, providing a lithium-containing feed may include providing a lithium sulfate solution. In some examples, the process may include reacting the lithium sulfate solution with a hydroxide. In some examples, the hydroxide may be sodium hydroxide, and the process may include producing an aqueous sodium sulfate solution, performing a cooling crystallization step to crystallize the aqueous sodium sulfate solution to obtain Glauber's salt, and separating Glauber's salt from the lithium hydroxide solution via a third solid-liquid separation step to obtain a purified lithium hydroxide solution. In some examples, the hydroxide may include barium hydroxide, and the process may include producing solid barium sulfate, and separating solid barium sulfate from the lithium hydroxide solution via a second solid-liquid separation step to obtain a purified lithium hydroxide solution. In some examples, forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate may include concentrating the purified lithium hydroxide solution. In some examples, concentrating the lithium hydroxide solution may include an evaporation step.

[0021] In some examples, providing a lithium-containing feed may include providing lithium chloride, which may include crude lithium chloride, technical grade lithium chloride, industrial grade lithium chloride, primary grade lithium chloride, battery grade lithium chloride, lithium chloride containing impurities, or any combination thereof. In some examples, the present process may include contacting the lithium-containing feed with hydrochloric acid to raise the temperature of the solution and obtain a lithium chloride solution. In some examples, providing the lithium-containing feed may include dissolving lithium carbonate, and this dissolution may include reacting lithium carbonate with an acid that may include hydrochloric acid to form a lithium chloride solution. In some examples, the present process may include contacting the lithium chloride solution with a hydroxide. In some examples, the hydroxide may be selected from sodium hydroxide or calcium hydroxide. In some examples, the present process may include removing precipitates from the lithium chloride solution after contact with the hydroxide through a third solid-liquid separation step. In some examples, the present process may include purifying the lithium chloride solution after the third solid-liquid separation step to obtain a purified lithium chloride solution.

[0022] In some examples, the purification of a lithium chloride solution may include a first purification by first ion exchange, which may include contacting the lithium chloride solution with a first resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof; and a second purification, which may include contacting the lithium chloride solution after the first purification with a second resin capable of removing carbonates, sulfates, or both. In some examples, the process may include concentrating the purified lithium chloride solution to obtain a concentrated lithium chloride solution. In some examples, the concentration of the purified lithium chloride solution may include reverse osmosis, evaporation, or both. In some examples, the process may include converting the concentrated lithium chloride solution into a concentrated lithium hydroxide solution by electrolysis, electrodialysis, or both. In some examples, forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate may include concentrating the concentrated lithium hydroxide solution formed by electrolysis, electrodialysis, or both.

[0023] In some cases, crystallizing lithium hydroxide monohydrate may involve concentrating a concentrated lithium hydroxide solution by evaporation.

[0024] In some examples, crystallizing lithium hydroxide monohydrate may involve cold crystallization. In some examples, forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate may involve performing an evaporation step. In some examples, this process may involve employing a heat pump arranged to provide cooling for cold crystallization and heating for the evaporation step.

[0025] In some cases, this process may involve one or more purifications of the crystallized lithium hydroxide monohydrate separated from the concentrated lithium hydroxide solution.

[0026] In some examples, the process may include drying and packaging the crystallized lithium hydroxide monohydrate separated from the concentrated lithium hydroxide solution.

[0027] In some examples, the process may involve separating the crystallized lithium hydroxide monohydrate and then recirculating the concentrated lithium hydroxide solution to produce further lithium hydroxide monohydrate.

[0028] In some examples, lithium hydroxide monohydrate formed by any of the above processes is provided, which may contain less than 2000 ppm of lithium carbonate.

[0029] Any combination of the features listed above may be implemented without deviating from the intent or scope of this disclosure, as will be further described in the detailed description below. Please understand that both the general description above and the detailed description below are typical and explanatory, and are intended to provide further explanation of the requested disclosure.

[0030] The accompanying drawings are included to provide a further understanding of the present invention, are incorporated herein and constitute part thereof, illustrate embodiments of the present invention, and are useful in illustrating the principles of the present invention together with the description. [Brief explanation of the drawing]

[0031] [Figure 1] This is a flowchart illustrating an example of a process for producing battery-grade lithium hydroxide monohydrate with a low lithium carbonate content. [Figure 2A] This is a flowchart illustrating an example of a process for producing battery-grade lithium hydroxide monohydrate with a low lithium carbonate content. [Figure 2B] This is a flowchart illustrating an example of a process for producing battery-grade lithium hydroxide monohydrate with a low lithium carbonate content. [Figure 3A]This is a flowchart illustrating an example of a process for producing battery-grade lithium hydroxide monohydrate with a low lithium carbonate content. [Figure 3B] This is a flowchart illustrating an example of a process for producing battery-grade lithium hydroxide monohydrate with a low lithium carbonate content. [Figure 4] This is a flowchart illustrating an example of a process for producing battery-grade lithium hydroxide monohydrate with a low lithium carbonate content. [Modes for carrying out the invention]

[0032] As previously mentioned, lithium hydroxide with a low carbonate content may be desirable for the manufacture of lithium batteries. In some examples, processes for producing battery-grade lithium hydroxide monohydrate are described herein. In some examples, the produced battery-grade lithium hydroxide monohydrate may have a low carbonate content.

[0033] In some examples, the processes described may include one or more of the following: lithium treatment, lithium refining and purification, production of lithium hydroxide monohydrate, evaporation and crystallization, softening, and ion exchange.

[0034] In some examples, a process for producing battery-grade lithium hydroxide monohydrate, which may contain a low carbonate content, is disclosed. In some examples, the process may include one or more of the following steps from a crude feed: leaching, purification, concentration, and crystallization.

[0035] In some cases, a low carbonate content refers to a carbonate content of less than 2000 ppm based on the total weight of the lithium hydroxide monohydrate material. In some cases, a lithium hydroxide monohydrate with a low carbonate content means a lithium hydroxide monohydrate in which the carbonate content is less than 2000 ppm. For example, the carbonate content of lithium hydroxide monohydrate having a low carbonate content that can be achieved by the processes described herein may be less than 2000 ppm, less than 1500 ppm, less than 1000 ppm, less than 500 ppm, or less than 100 ppm. This is distinguishable from typical battery-grade lithium hydroxide monohydrate, which can contain up to approximately 4700 ppm of carbonate.

[0036] In some cases, a low carbonate content may be desirable for the conversion from lithium hydroxide monohydrate to lithium sulfide.

[0037] The processes disclosed herein may yield low-carbonate products that can be used in any application where carbonates are undesirable.

[0038] In some examples, the processes described herein may involve crystallizing lithium hydroxide monohydrate from a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate and containing a low level of lithium carbonate. In some examples, the concentrated lithium hydroxide solution may be formed to contain a low concentration of lithium carbonate. In some examples, the concentrated lithium hydroxide solution may be purged of lithium carbonate before the crystallization of lithium hydroxide monohydrate. In some examples, the processes described herein may involve crystallizing lithium hydroxide monohydrate from a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate and containing Li2CO3 at concentrations of 2000 ppm or 0.2 wt%, for example, 1500 ppm or 0.15 wt%, for example, 1000 ppm or 0.1 wt%, for example, 500 ppm or 0.05 wt%, for example, 100 ppm or 0.01 wt%. For the purposes of this description, when a solution is described as “saturated” with lithium hydroxide monohydrate, it means that the solution is 100% saturated with lithium hydroxide monohydrate. For the purposes of this description, when a solution is described as “approximately saturated” with lithium hydroxide monohydrate, it means that the level of saturation of lithium hydroxide monohydrate in the solution is at least 80% saturated, at least 85% saturated, at least 90% saturated, at least 95% saturated, at least 97% saturated, or at least 99% saturated.

[0039] In some examples, the process described herein may include the removal of carbonate at or just before saturation of lithium hydroxide monohydrate from a lithium hydroxide solution. In some examples, the process described herein may obtain lithium hydroxide monohydrate from a lithium hydroxide solution by a concentration step, such as evaporation. In some examples, the lithium hydroxide solution may be heated to evaporate water from the solution. In some examples, the solution may be monitored for lithium carbonate formation during concentration. In some examples, when the lithium hydroxide monohydrate from lithium hydroxide is saturated by concentration, or just before saturation is reached, the process described herein may include the extraction of the formed lithium carbonate. In some examples, the extraction of lithium carbonate may be carried out by a solid-liquid separation step or other suitable filtration.

[0040] In some cases, lithium hydroxide monohydrate can then be obtained by concentrating a concentrated lithium hydroxide solution with a low carbonate content, which is saturated or nearly saturated with lithium hydroxide monohydrate, by an evaporation step and / or a cooling crystallization step.

[0041] For the purposes of this description, when referring to the stopping point for removing lithium carbonate from a concentrated LiOH solution, "just before saturation" is used to refer to the state in which at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or at least 99% saturation of lithium hydroxide monohydrate is achieved in the concentrated solution. For the purposes of this description, when referring to the stopping point for removing lithium carbonate from a concentrated LiOH solution, "at saturation" is used to refer to the state in which 100% saturation of lithium hydroxide monohydrate is achieved in the concentrated solution.

[0042] In some cases, lithium hydroxide monohydrate obtained by continuing evaporation and / or cooling crystallization after separating lithium carbonate will have fewer carbonate impurities than lithium hydroxide monohydrate obtained by conventional processes. In some cases, the cooling crystallization step can reduce the carbonate content in lithium hydroxide monohydrate compared to continuing evaporation.

[0043] In some examples, the processes described herein may involve obtaining a lithium hydroxide solution that can be used to obtain lithium hydroxide monohydrate. In some examples, the lithium hydroxide solution may be obtained from a crude feed or other raw materials containing impurities.

[0044] In some examples, the starting material may include lithium carbonate, such as crude lithium carbonate. In some examples, the process described herein may include the dissolution of crude lithium carbonate. In some examples, the dissolution of crude lithium carbonate may be carried out using an acid and / or alkaline earth hydroxide.

[0045] In some cases, a lithium carbonate feed can be used to form a lithium hydroxide feed, from which a lithium hydroxide monohydrate can be obtained. In some cases, a lithium hydroxide solution can be obtained by first reacting the lithium carbonate feed with an acid to form a lithium salt, and then reacting that salt with a metal hydroxide. In some cases, the acid is hydrochloric acid (HCl) or sulfuric acid (H2SO4). In some cases, a lithium hydroxide solution can be obtained from a lithium carbonate feed by a direct reaction with an alkaline earth hydroxide. In some cases, the alkaline earth hydroxide may be calcium hydroxide (Ca(OH)2).

[0046] In some examples, the starting material may already contain a lithium hydroxide solution. In some examples, the starting lithium hydroxide solution may contain any level of impurities. In some examples, the lithium hydroxide solution may contain lithium hydroxide monohydrate, lithium hydroxide anhydrous, or both. In some examples, the starting hydroxide solution may be a crude lithium hydroxide solution, a technical grade lithium hydroxide solution, an industrial grade lithium hydroxide solution, a primary grade lithium hydroxide solution, a battery grade lithium hydroxide solution as can be produced by other processes, or any mixture thereof.

[0047] In some cases, this process may include ion exchange treatment. In some cases, ion exchange may be performed when dissolving crude lithium carbonate with an acid and / or alkaline earth hydroxide. In some cases, ion exchange may be employed to remove carbonates and sulfates, and / or cations such as calcium, magnesium, and other polyvalent cations.

[0048] Herein, we will refer in detail to embodiments of the present disclosure, which are illustrated in the attached drawings.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this disclosure belongs. All patents, patent applications, published applications and publications, websites and other public materials referenced throughout this disclosure are incorporated by reference throughout unless otherwise noted. If a term has multiple definitions in this disclosure, the definition in this section shall prevail. Where a URL or other such identifier or address is referenced, it is understood that such identifiers may change, and information on the Internet may be added or removed, although equivalent information may be found by searching the Internet. By referring to such information, it is acknowledged that it is available and publicly distributed.

[0050] As used herein, the singular forms "a," "an," and "the" refer to multiple objects unless the context clearly indicates otherwise.

[0051] The terms "first," "second," "third," etc., as used herein, can describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections are not limited by these terms. These terms may be used solely to distinguish one element, component, region, layer, or section from another region, layer, or section. The terms "first," "second," etc., and other numerical terms, as used herein, do not imply order or sequence unless clearly indicated by the context. Thus, the first element, component, region, layer, or section described below may be referred to as the second element, component, region, layer, or section without departing from the teaching of the exemplary embodiments.

[0052] As used herein, ranges and quantities may be expressed as “approximately” a particular value or range. “Approximately” also includes exact quantities. Thus, “approximately 5 percent” means approximately 5 percent in addition to 5 percent. The term “approximately” means within the range of typical experimental error for the intended use or purpose.

[0053] As used herein, "and / or" includes all possible combinations of one or more of the related list items.

[0054] As used herein, “combination” refers to any association between two or more items. This association may be spatial, or it may refer to the use of two or more items for a common purpose.

[0055] As used herein, the terms “comprising” and “comprises” should be interpreted as “including but not limited to” and “includes but not limited to,” respectively.

[0056] As used herein, “optional” or “optional” means whether or not the events or situations described herein may or may not occur, and the descriptions include both cases in which the events or situations may and may not occur. For example, “optional components in the system” means that the components may or may not exist in the system.

[0057] As used herein, “substantially” means “mostly but not entirely” of what is specified.

[0058] Figure 1 is a flow chart of an example of process 100 for producing low-carbonate battery grade lithium hydroxide monohydrate.

[0059] In some cases, as shown in Figure 1, low-carbonate battery grade lithium hydroxide monohydrate can be obtained by removing at least some lithium carbonate from a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate before the crystallization of lithium hydroxide monohydrate.

[0060] In some examples, this process may involve forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate, with a low level of lithium carbonate. In some examples, at least a portion of the lithium carbonate is removed from the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate.

[0061] In some examples, a LiOH solution may be provided, as shown in 102, or a LiOH solution may be produced, as will be described in more detail later. In some examples, the LiOH solution may be a LiOH solution of any impurity concentration. In some examples, a LiOH solution may be produced. In some examples, the LiOH solution may be produced from a lithium feedstock. In some of the examples described later, the lithium feedstock may contain lithium carbonate and / or lithium sulfate. In some examples, a LiOH solution may be provided. In some examples, the provided LiOH solution may be a crude LiOH solution, a technical grade LiOH solution, an industrial grade LiOH solution, a primary grade LiOH solution, a battery grade LiOH solution, or any mixture thereof.

[0062] In some examples, the process may involve concentrating the LiOH solution in 104. In some examples, the concentration of the LiOH solution may be by evaporation. In some examples, the LiOH solution may be heated to its boiling point and evaporated until saturation or near-complete saturation of lithium hydroxide monohydrate is reached. In some examples, evaporation may be carried out under atmospheric pressure at a temperature range of 110–120°C. In some examples, the concentration step may involve multiple stages of evaporation. In some examples involving multiple stages of evaporation or under vacuum, the process may be carried out at a temperature range of 30–120°C.

[0063] In some cases, the accumulation of impurities during the process can be controlled by stopping the concentration (e.g., evaporation) when the lithium hydroxide monohydrate is saturated or just before it reaches saturation, and by removing the impurities precipitated during the concentration process before the crystallization of the lithium hydroxide monohydrate can proceed. In some cases, the concentration process can be carried out until at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 99%, or 100% saturation of the lithium hydroxide monohydrate in the solution is achieved, after which the impurities can be removed.

[0064] In some cases, solid impurities may precipitate as a result of the concentration process at 104. In some cases, the precipitated solid impurities may include Li2CO3. Other metallic impurities may also precipitate. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…)+yOH - (aqueous solution)→ M x OH y (Solid) or SiO2 (Solid) Li2CO3 (aqueous solution) → Li2CO3 (solid)

[0065] In some cases, the precipitated impurities, including precipitated carbonates, may be removed following the concentration step. In some cases, solid-liquid separation may be performed after concentration. Solid-liquid separation may be performed by any preferred method. Non-limiting examples of solid-liquid separation may include the use of one or more filters, thickeners, or a combination of different solid-liquid separation techniques.

[0066] In some cases, the separated solid can be discarded, further processed, or recycled to generate additional lithium hydroxide solution.

[0067] In some examples, a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate in 108, from which at least some lithium carbonate has been removed from 106, may be further concentrated or cooled and crystallized to obtain a lithium hydroxide monohydrate salt. In some examples, further concentration may be achieved by further evaporation. By performing further evaporation and / or cooled and crystallized, it may be possible to crystallize the saturated lithium hydroxide monohydrate in the solution. LiOH (aqueous solution) + H2O → LiOH*H2O (solid)

[0068] In some cases, cooling crystallization can result in a lower carbonate content than crystallization by additional evaporation. This is because additional evaporation can lead to the formation of more Li2CO3. In some cases, cooling crystallization is carried out at a sufficiently low temperature that Li2CO3 remains soluble. As a result, a precipitate consisting mostly of lithium hydroxide monohydrate is obtained. In some cases where lithium hydroxide monohydrate is obtained by cooling crystallization, the final cooling temperature is approximately 23–40°C.

[0069] In some cases, cold crystallization may be advantageous from the standpoint of energy consumption processes because it does not require additional heating. In some cases, cold crystallization may be advantageous because it avoids the need to pass the solution through a heat exchanger that requires cleaning. In some cases, cold crystallization may enable energy integration via a heat pump. In some cases, cold crystallization will be carried out at a temperature lower than the temperature at which the LiOH solution is first concentrated by evaporation. Therefore, in some cases, a heat pump may be provided to heat the solution during the concentration process by evaporation and to cool the solution during cold crystallization. Thus, using a heat pump for energy integration between the concentration evaporation process and cold crystallization may lead to a reduction in energy consumption. Cold crystallization may also be advantageous in that it may yield crystallized lithium hydroxide monohydrate with a lower water content compared to crystallized lithium hydroxide monohydrate obtained by evaporation.

[0070] In some cases, removing Li2CO3 before crystallizing lithium hydroxide monohydrate makes it possible to obtain battery-grade lithium hydroxide monohydrate with carbonate content of less than 2000 ppm, less than 1500 ppm, less than 1000 ppm, less than 500 ppm, or less than 100 ppm.

[0071] In some cases, crystallized lithium hydroxide monohydrate can be separated from the solution, washed and / or purified, dried, and packaged.

[0072] In some cases, the crystallized lithium hydroxide monohydrate salt can be removed from the solution via any suitable solid-liquid separation. In some cases, the solid-liquid separation can be carried out using one or more hydrocyclos in combination with one or more centrifuges. In some cases, the solid-liquid separation may include washing the resulting filtration cake. In some cases, the remaining solution after filtration of the crystallized lithium hydroxide monohydrate can be recycled in the process to recover the remaining lithium.

[0073] In some examples, the purification of the crystallized lithium hydroxide monohydrate may be carried out by one or more redissolution and recrystallization steps, and / or one or more reslurrying and solid-liquid separation steps, until the product meets the specifications of the desired battery grade. In some examples, redissolution may be carried out with pure water that is free of or nearly free of CO2.

[0074] In some cases, the concentrated lithium hydroxide solution formed in 102, from which lithium hydroxide monohydrate is ultimately obtained, can be formed or produced from a lithium feedstock. In some cases, the lithium feedstock may contain lithium hydroxide. In some cases, the lithium feedstock may contain lithium carbonate. In some cases, the lithium feedstock may contain lithium sulfate. In some cases, the lithium feedstock may contain lithium chloride.

[0075] In some cases, combining the production of concentrated lithium hydroxide solution with the formation of lithium hydroxide monohydrate with a low carbonate content, as described above, may be advantageous because it can provide a means of more easily transporting the raw materials. For example, lithium carbonate and / or lithium sulfate can be transported more easily than lithium hydroxide solution, lithium hydroxide monohydrate, or lithium hydroxide anhydrous.

[0076] In some cases, lithium feedstock starting materials may contain impurities of any concentration. In some cases, lithium feedstocks may be crude feedstocks, technical grade feedstocks, industrial grade feedstocks, battery grade feedstocks, primary grade feedstocks, or any mixture thereof. For example, if the lithium feedstock is a lithium hydroxide solution, it may be crude lithium hydroxide, technical grade lithium hydroxide, industrial grade lithium hydroxide, battery grade lithium hydroxide, primary grade lithium hydroxide, or any mixture thereof. For example, if the lithium feedstock is lithium carbonate, it may be crude lithium carbonate, technical grade lithium carbonate, industrial grade lithium carbonate, battery grade lithium carbonate, primary grade lithium carbonate, or any mixture thereof. For example, if the lithium feedstock is lithium sulfate, it may be crude lithium sulfate, technical grade lithium sulfate, industrial grade lithium sulfate, battery grade lithium sulfate, primary grade lithium sulfate, or any mixture thereof. For example, if the lithium feedstock is lithium chloride, it may be crude lithium chloride, technical grade lithium chloride, industrial grade lithium chloride, battery grade lithium chloride, primary grade lithium chloride, or a mixture thereof.

[0077] In some cases, lithium hydroxide solutions can be obtained by dissolving lithium-supplying materials such as lithium carbonate or lithium sulfate. In some cases, the dissolution of lithium-supplying materials can be carried out via an acid or using alkaline earth hydroxides.

[0078] Figures 2A and 2B show example process flow diagrams for producing lithium hydroxide monohydrate, starting from lithium feedstocks of lithium carbonate and / or lithium sulfate. In some examples, when starting with lithium carbonate, as illustrated, the dissolution of crude lithium carbonate may be carried out using an acid such as sulfuric acid. In some examples, this process may be carried out as shown in Figures 2A and 2B.

[0079] Figure 2A shows an example of process 200. In some examples, in process 200, the crude lithium carbonate may be dissolved by contact with 0-10% excess sulfuric acid at atmospheric pressure and a temperature in the range of 70°C-90°C. In some examples, this process can be carried out in any suitable apparatus, such as a continuous stirred tank reactor. Carrying this step at a high temperature can be improved and ensured that the solubility of CO2 in the solution can be kept as low as possible. The reaction mechanism is shown by the following equation. Li2CO3 (solid) + H2SO4 (aqueous solution) → Li2SO4 (aqueous solution) + CO2 (gas) + H2O

[0080] In some cases, the reaction produces Li2SO4. In some cases, the reaction is carried out to achieve a concentration of Li2SO4 that avoids or limits the crystallization of Li2SO4*H2O. In some cases, the maximum concentration of Li2SO4 can be approximately 250 g / kgH2O.

[0081] In some cases, if the starting lithium feed in process 200 is already a Li2SO4 solution instead of lithium carbonate, the dissolution in 202 may be omitted. The solution containing the dissolved Li2SO4 may be available as an intermediate product of lithium leaching from hard rocks such as spodumene. In some cases, additional Li2SO4 solution may be optionally added to the Li2SO4 solution produced in 202 in 206 or immediately before that.

[0082] In some cases, a solution containing dissolved Li2SO4 can be caustrated with a hydroxide to obtain a LiOH solution. In some cases, the hydroxide can be any suitable material that can react with lithium sulfate to produce a LiOH solution. In some cases, the hydroxide can be NaOH or Ba(OH)2.

[0083] Figure 2A shows a process in which sodium hydroxide (NaOH) is used as the hydroxide. 。In some cases, sodium hydroxide can be added to a lithium sulfate solution in 206 to obtain a sodium sulfate and LiOH solution as shown in the following formula. In some cases, the reaction can be carried out under atmospheric pressure at a temperature in the range of 70°C to 90°C. In some cases, the addition of excess sodium hydroxide may be unnecessary. Li2SO4(aqueous solution)+2NaOH(aqueous solution)→ Na2SO4(aqueous solution)+2LiOH(aqueous solution)

[0084] In some examples, in 204, an ion exchange treatment using one or more resins may be performed to remove carbonates and purify the sodium hydroxide solution before it is used in the caustication step in 206. In some examples, the ion exchange treatment may involve the use of any suitable resin, and in some examples, the resin may include a styrene resin as a polystyrene-divinylbenzene resin.

[0085] In some cases, it may also be possible to introduce one or more recirculated solutions generated in 218, 222, and / or 226, as described below, into 206.

[0086] In some cases, the caustic yield at 206 was approximately 288 g / kg H2O for aqueous sodium sulfate (Na2SO4(aqueous solution)) and approximately 172 g / kg H2O の It may include a stream containing concentrated LiOH (aqueous solution).

[0087] In some examples, at 208 and 210, the product effluent from 206 may be treated to remove at least a portion of the Na2SO4. In some examples, the aqueous Na2SO4 solution may be removed by precipitating Glauber's salt (Na2SO4.10H2O) at 208, and then removing the precipitate at 210 via any suitable solid-liquid separation. In some examples, the precipitation of Glauber's salt may be induced by cooling crystallization at temperatures in the range of about 0°C to 7°C. Na2SO4(aqueous solution)+10H2O→Na2SO4*10H2O(solid)

[0088] In some examples, after crystallization, the Na2SO remaining in the solution 4( (aqueous solution) content may be in the range of about 106 to 142 g / kg H2O (depending on the final temperature). The concentration of LiOH (aqueous solution) in the resulting solution may be as high as 200 g / kg H2O.

[0089] In some examples, at 210, solid-liquid separation of Glauber's salt may be performed to remove Glauber's salt from the solution. Any suitable solid-liquid separation may be applied. In some examples, the solid-liquid separation may be a filtration process. In some examples, filtration may be performed using a centrifuge. In some examples, the residual moisture in the Glauber's salt cake removed from the solution after solid-liquid separation may be in the range of about 3 to 10% based on the total mass of the separated cake.

[0090] In some examples, the LiOH solution after removing Glauber's salt can be used to produce lithium hydroxide monohydrate, as previously described with reference to Figure 1. In some examples, at 212, the LiOH solution may be concentrated. As previously described, in some examples, concentration may be achieved by evaporation. In some examples, evaporation may be performed at a temperature in the range of about 110 to 120°C. In some examples, concentration may be performed at atmospheric pressure using any suitable equipment. In some examples involving multi-stage evaporation or under vacuum, the temperature range may be from about 30 to about 120°C. In some examples, the evaporation may include heating the LiOH solution produced after separation of Glauber's salt at 210 to its boiling point, and evaporating until saturation of lithium hydroxide monohydrate in the concentrated solution is reached, or just before saturation is reached, as previously described. As a result of this concentration step, solid impurities including Li2CO3 may precipitate through the following mechanism. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…) + yOH - (aqueous solution)→ M x OH y(Solid) or SiO2 (Solid) Li2CO3 (aqueous solution) → Li2CO3 (solid)

[0091] In some examples, solid-liquid separation may be performed in 214 after concentration is complete in 212. As previously mentioned, solid-liquid separation may be performed by any suitable means. In some examples, solid-liquid separation may involve using one or more filters, thickeners, centrifuges, or any combination of different solid-liquid separation techniques. In some examples, the solid separated from 214 may be recycled to 202 so that the precipitated Li2CO3 can dissolve again to produce more LiOH. In some examples, this recycling may facilitate the recovery of lithium during the process. In some examples, the accumulation of recycled impurities during the process may be controlled by stopping evaporation when lithium hydroxide monohydrate is saturated or just before it reaches saturation, and removing the formed impurities before the crystallization of lithium hydroxide monohydrate can proceed. Other methods may also be employed.

[0092] In 216, the saturated lithium hydroxide monohydrate in the concentrated solution can crystallize. In some cases, crystallization can be achieved by restarting the concentration process and continuing evaporation, as described above, or by cooling crystallization. When using cooling crystallization, the final cooling temperature can be approximately 23°C to 40°C. In some cases, crystallization follows the following mechanism. LiOH (aqueous solution) + H2O → LiOH*H2O (solid)

[0093] In some cases, after the crystallization of lithium hydroxide monohydrate, the remaining solution may contain Na2SO4 (aqueous solution) at a maximum concentration of approximately 288 g / kg H2O and LiOH (aqueous solution) at a maximum concentration of approximately 168-210 g / kg H2O, depending on the final temperature and the concentration of Na2SO4.

[0094] In step 218, the crystallized lithium hydroxide monohydrate salt can be removed from the solution by any suitable solid-liquid separation. In some examples, the solid-liquid separation may be carried out using one or more hydrocyclones in combination with one or more centrifuges. In some examples, in step 218, the solid-liquid separation may include washing the resulting filter cake. In some examples, the residual water content in the lithium hydroxide monohydrate after solid-liquid separation may be in the range of about 1-5% based on the total mass of the cake. In some examples, the resulting lithium hydroxide monohydrate is a lithium hydroxide monohydrate with a low carbonate content.

[0095] In some cases, the remaining LiOH solution after removing lithium hydroxide monohydrate salt in 218 can be recycled to 206. Recirculating this residue can reduce lithium loss in process 200. In some cases, a portion of the liquid can be purged to prevent the accumulation of impurity concentrations within the process.

[0096] In some cases, the lithium hydroxide monohydrate salt or cake collected in 218 may be further processed through one or more optional reslurrying and separation steps to remove impurities and achieve the desired purity level to obtain the final purified lithium hydroxide monohydrate salt. If the purity of the lithium hydroxide monohydrate salt collected in 218 exceeds the desired threshold, the reslurrying and separation steps are not necessary, and the salt from 218 may be used as the final purified lithium hydroxide monohydrate salt.

[0097] In some examples, the lithium hydroxide monohydrate salt or cake collected in 218 may be treated in a first reslurrying step 220. In some examples, in 220, in reslurrying step 1, the lithium hydroxide monohydrate collected in 218 may be reslurried with high-purity water in a stirred tank to obtain a first reslurrying solution. In this way, soluble impurities present in the lithium hydroxide monohydrate solid may migrate to the added water, thereby further reducing the level of impurities that may be present in the lithium hydroxide monohydrate. In some examples, reslurrying step 1 in 220 may be performed in addition to any washing steps that may be performed in 218 as part of solid-liquid separation.

[0098] In some cases, the reslurrying step 1 at 220 may be carried out at atmospheric pressure and a temperature of approximately 30°C to 40°C. Any suitable equipment may be used for reslurrying. In some cases, the solid-liquid ratio of the first slurrying solution, i.e., the solid-liquid ratio in the reslurrying step 1 at 220, may be 1 to 3, depending on the levels of impurities and moisture present in the resulting solid or cake. It should be noted that during the reslurrying step 1, some of the lithium hydroxide monohydrate may dissolve and be lost into the solution.

[0099] In some examples, at 222, lithium hydroxide monohydrate can be separated from the first reslurried solution of reslurried step 1 at 220 via a first solid-liquid separation, i.e., solid-liquid separation step 1. In some examples, solid-liquid separation step 1 at 220 can be carried out by any preferred process. In some examples, solid-liquid separation step 1 at 220 can be carried out using a centrifuge and / or filter. In some examples, the remaining solution after removing the reslurried lithium hydroxide monohydrate of the first step can be recycled to 206. Recirculating this residue can reduce lithium loss in process 200. In some examples, a portion of the remaining solution can be purged to prevent impurities from concentrating and accumulating in the process. In some examples, at 222, the residual water content in the lithium hydroxide monohydrate salt after solid-liquid separation can be in the range of approximately 3-10%.

[0100] In some examples, at 224, process 200 may optionally include a second reslurrying step, reslurrying step 2. In some examples, at 224, the solid cake of lithium hydroxide monohydrate reslurried in the first step from 222 may be reslurried a second time with high-purity water in a stirred tank. In some examples, reslurrying step 2 at 224 may be carried out at atmospheric pressure and a temperature of approximately 30°C to 40°C. In some examples, in this process, soluble impurities present in the solid lithium hydroxide monohydrate may migrate to the added water, thereby reducing the level of impurities present in the solid lithium hydroxide monohydrate. In some examples, the solid-liquid ratio of the second repulping solution, i.e., the solid-liquid ratio in reslurrying step 2 at 224, may be 1 to 3 depending on the level of impurities and moisture present in the resulting solid or cake. Note that during reslurrying step 2, some of the lithium hydroxide monohydrate may dissolve and be lost into the solution.

[0101] In some examples, at 226, lithium hydroxide monohydrate can be separated from the second reslurried solution of reslurried step 2 at 222 via a second solid-liquid separation, solid-liquid separation step 2. In some examples, solid-liquid separation step 2 at 226 can be carried out by any suitable process. In some examples, solid-liquid separation step 2 at 226 can be carried out using a centrifuge and / or filter. In some examples, the remaining solution after removing the reslurried lithium hydroxide monohydrate of the second step can be recycled to 206. Recirculating this residue can reduce lithium loss in process 200. In some examples, a portion of the remaining solution can be purged to prevent impurities from concentrating and accumulating in the process. In some examples, at 226, the residual water content after solid-liquid separation can be in the range of approximately 3-10%.

[0102] In some examples, in step 228, further purification of the crystallized lithium hydroxide monohydrate may be optionally performed by one or more redissolution and recrystallization steps, and / or one or more additional reslurrying and filtration steps, until the product meets the specifications of the desired battery grade. In some examples where the optional second reslurrying step is omitted, step 228 may follow immediately after 222.

[0103] In some cases, the final purified lithium hydroxide monohydrate salt or cake may be battery grade. In some cases, the final purified lithium hydroxide monohydrate salt or cake may have a low carbonate content of less than 2000 ppm, less than 1500 ppm, less than 1000 ppm, less than 500 ppm, or less than 100 ppm.

[0104] In some cases, at 229, the final purified lithium hydroxide monohydrate battery-grade salt or cake may be sent to one or more drying and packaging stages.

[0105] In some examples, process 200 and each of its steps may be carried out in an atmosphere that is free of or contains little to no CO2. An atmosphere that is free of or contains little to no CO2 can keep CO2 absorption from the air as low as possible. In some examples, the drying of lithium hydroxide monohydrate may be carried out in high-temperature, CO2-free air.

[0106] Figure 2B shows process 230, which is similar to that described with reference to Figure 2A, except that the hydroxide used in step 236 is barium hydroxide (Ba(OH)2) instead of sodium hydroxide.

[0107] In some cases, step 232 is the same as step 202 described above. In some cases, if the starting lithium feed in step 230 is a solution that already contains dissolved Li2SO4 instead of lithium carbonate, the dissolution in 232 may be omitted. In some cases, an additional Li2SO4 solution is added to the Li2SO4 solution produced in 232 in 236, or immediately before 236. It may be added at will. Also, in some examples, in 234, an ion exchange treatment of the carbonate, as described earlier with reference to 204, may be used to purify the barium hydroxide solution before use in the caustic process in 236.

[0108] In some examples, barium hydroxide is added to the lithium sulfate solution produced in 232 at 236, and a solution of barium sulfate (BaSO4) and LiOH can be obtained as shown by the following formula.

[0109] In some cases, it may be possible to introduce one or more recirculated solutions generated in 248, 252 and / or 256, described below, into 236.

[0110] In some cases, the reaction can be carried out under atmospheric pressure at temperatures ranging from 70°C to 90°C. In some cases, the addition of excess barium hydroxide may be unnecessary. In some cases, the resulting solution may contain LiOH in concentrations ranging from 3 wt% to saturation. In some cases, the solution may contain a LiOH concentration of approximately 7.2 wt%. Li2SO4 (aqueous solution) + Ba(OH)2 (solid) → BaSO4 (solid) + 2LiOH (aqueous solution)

[0111] In step 240, barium sulfate can be removed from the LiOH solution via a solid-liquid separation step. Note that since barium sulfate has lower solubility than sodium sulfate, it can be removed by solid-liquid separation without first requiring the cooling crystallization step 208 described with reference to Figure 2A when removing sodium sulfate. Thus, when barium hydroxide is used as the hydroxide instead of sodium hydroxide, step 208 can be omitted. In some examples, any suitable solid-liquid separation can be applied. In some examples, solid-liquid separation can be performed by filtration. In some examples, filtration can be performed using a centrifuge. In some examples, the residual water content in the solution after solid-liquid separation can be in the range of approximately 30-60%. In some examples, solid-liquid separation may include one or more washing steps of the filtered solid or cake to reduce lithium loss.

[0112] In some cases, the LiOH solution after removing barium sulfate in 240 can be used to produce lithium hydroxide monohydrate, as previously described with reference to Figure 1. In some cases, the LiOH solution can be concentrated in 242, as similarly described in 212 with reference to process 200. As previously described, in some cases, concentration can be achieved by evaporation. In some cases, evaporation can be carried out at temperatures in the range of about 110–120°C. In some cases, concentration can be carried out under atmospheric pressure using any suitable equipment. In some cases involving multiple stages of evaporation or under vacuum, the temperature range can be in the range of about 30–120°C. In some cases, the evaporation may involve heating the LiOH solution produced after the separation of barium sulfate in 240 to its boiling point and evaporating it until saturation of lithium hydroxide monohydrate in the concentrated solution is reached, or just before saturation is reached, as previously described. As a result of this concentration step, solid impurities containing Li2CO3 may precipitate by the following mechanism. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…)+yOH - (aqueous solution)→ M x OHy (Solid) or SiO2 (Solid) Li2CO3 (aqueous solution) → Li2CO3 (solid)

[0113] In some examples, solid-liquid separation may be performed in 244 after the concentration is complete, as previously described with reference to process 200 in 214. As previously stated, solid-liquid separation may be performed by any suitable means. In some examples, solid-liquid separation may involve using one or more filters, thickeners, centrifuges, or any combination of different solid-liquid separation techniques. In some examples, the solid separated from 244 may be recycled to 232 so that the precipitated Li2CO3 can dissolve again to produce more LiOH. In some examples, this recycling may facilitate the recovery of lithium in the process. In some examples, the accumulation of recycled impurities in the process may be controlled by stopping evaporation when lithium hydroxide monohydrate is saturated or just before it reaches saturation, and removing the formed impurities before the crystallization of lithium hydroxide monohydrate can proceed. Other methods may also be employed.

[0114] In 246, saturated lithium hydroxide monohydrate in the concentrated solution may be crystallized, as similarly described in 216 with reference to process 200. In some examples, crystallization may be achieved by restarting the concentration process and continuing evaporation, as previously stated, or by cold crystallization. When using cold crystallization, the final cooling temperature may be approximately 23°C to 40°C. In some examples, crystallization follows the following mechanism. LiOH (aqueous solution) + H2O → LiOH*H2O (solid)

[0115] In 248, the crystallized lithium hydroxide monohydrate salt can be removed from the solution by any suitable solid-liquid separation, as similarly described in 218 with reference to process 200. In some examples, the solid-liquid separation may be carried out using one or more hydrocyclones in combination with one or more centrifuges. In some examples, in 248, the solid-liquid separation may include washing the resulting filter cake. In some examples, the residual water content in the lithium hydroxide monohydrate after solid-liquid separation may be in the range of about 1-5% based on the total mass of the cake. In some examples, the lithium hydroxide monohydrate produced is a lithium hydroxide monohydrate with a low carbonate content.

[0116] In some cases, the remaining LiOH solution after removing lithium hydroxide monohydrate salt in 248 can be recycled to 236. Recycling this residue can reduce lithium loss in process 230. In some cases, a portion of the liquid can be purged to prevent the accumulation of impurity concentrations within the process.

[0117] In some cases, the lithium hydroxide monohydrate salt or cake collected in 248 may be further processed through one or more optional reslurrying and separation steps 250-256, as previously described with reference to process 200 in 220-226, to remove impurities and achieve the desired purity level to obtain the final purified lithium hydroxide monohydrate salt. If the purity of the lithium hydroxide monohydrate salt collected in 248 is below the desired threshold, the reslurrying and separation steps are not necessary, and the salt from 248 may be used as the final purified lithium hydroxide monohydrate salt.

[0118] In some cases, as described above, in 258, further purification of the crystallized lithium hydroxide monohydrate may be optionally carried out by one or more redissolution and recrystallization steps, and / or one or more additional reslurrying and filtration steps, until the product meets the specifications of the desired battery grade.

[0119] In some cases, the final purified lithium hydroxide monohydrate salt or cake may be battery grade. In some cases, the final purified lithium hydroxide monohydrate salt or cake may have a low carbonate content of less than 2000 ppm, less than 1500 ppm, less than 1000 ppm, less than 500 ppm, or less than 100 ppm.

[0120] In some cases, at 260°C, the final purified lithium hydroxide monohydrate battery-grade salt or cake may be sent to one or more drying and packaging stages.

[0121] In some examples, process 230 and each of its steps may be carried out in an atmosphere that is free of or contains little to no CO2. An atmosphere that is free of or contains little to no CO2 can keep CO2 absorption from the air as low as possible. In some examples, the drying of lithium hydroxide monohydrate may be carried out in high-temperature, CO2-free air.

[0122] Figures 3A and 3B show example process flow diagrams for producing lithium hydroxide monohydrate, starting from a lithium feed of lithium carbonate, which is dissolved using an alkaline earth hydroxide. In some examples, as described with reference to Figures 3A and 3B, the alkaline earth hydroxide may include calcium hydroxide (Ca(OH)2). In some examples, the process may include one or more softening and ion exchange treatments to remove unwanted carbonates and sulfates, as well as / or unwanted calcium, magnesium, and other polyvalent cations. In some examples, this process may be carried out as shown in Figures 3A and 3B.

[0123] Figure 3A shows an example of process 300. In some examples, in 302, the supply of lithium carbonate, for example, a supply of crude lithium carbonate, may be brought into contact with calcium hydroxide. In some examples, lithium carbonate may dissolve upon contact with calcium hydroxide. In some examples, calcium hydroxide may be supplied in excess, ranging from 0 to 50%. In some examples, the dissolution of lithium carbonate may be carried out in a continuously stirred reactor under atmospheric pressure.

[0124] In some examples, the reaction mechanism for dissolution at 302 is shown by the following equation. Li2CO3 (solid) + H2O → Li2CO3 (aqueous solution) Ca(OH)2 (solid) + H2O → Ca(OH)2 (aqueous solution) Li2CO3 (aqueous solution) + Ca(OH)2 (aqueous solution)→ CaCO3 (solid) + 2LiOH (aqueous solution) + H2O

[0125] In some cases, as shown in the above formula, dissolving lithium carbonate with an alkaline earth hydroxide such as calcium hydroxide can yield a LiOH solution containing solid calcium carbonate.

[0126] In some cases, the dissolution of lithium carbonate using alkaline earth hydroxides such as calcium hydroxide is carried out at room temperature, i.e., in the range of approximately 25°C to 90°C. It has been found that dissolution below room temperature results in a low conversion rate at such low temperatures, potentially making it impossible to obtain an acceptable LiOH solution. Furthermore, it has been found that dissolution at temperatures above 90°C does not form solid calcium carbonate crystals with the size and morphological characteristics that make separation from the LiOH solution difficult, resulting in high residual water content and increased lithium loss during solid-liquid separation.

[0127] In 304, solid calcium carbonate can be separated from the LiOH solution formed by the dissolution of lithium carbonate in 302. In some examples, the separation of calcium carbonate can be carried out via a solid-liquid separation step. In some examples, the solid-liquid separation step can be carried out by any suitable means. In some examples, this process can be carried out using a pressure filter. In some examples, the residual moisture content of the calcium carbonate cake or solid separated from the LiOH solution may be in the range of 40-70%.

[0128] In some examples, if a LiOH solution is provided as the starting lithium feed instead of lithium carbonate in process 300, the dissolution and separation in 302 and 304 may be omitted. Any LiOH solution can be used as the starting material. In some examples, the provided LiOH solution may be a crude LiOH solution, a technical grade LiOH solution, an industrial grade LiOH solution, a primary grade LiOH solution, a battery grade LiOH solution, or any mixture thereof. In some examples, an additional LiOH solution may be added to the LiOH solution produced in 304 in 306, or immediately before 306. It can be added at will.

[0129] In some cases, the LiOH solution produced in 304, i.e., the LiOH solution after solid-liquid separation of calcium carbonate, can be purified in 306. In some cases, the purification may involve softening the LiOH solution. In some cases, the purification of the LiOH solution in 306 may involve ion exchange treatment. In some cases, the ion exchange treatment may be carried out at a temperature of about 50°C. In some cases, the ion exchange treatment may involve the use of any suitable resin, and in some cases, the resin may include a styrene resin as a polystyrene-divinylbenzene resin. In some cases, the ion exchange treatment may involve the use of one or more resins that can be used to remove carbonates and sulfates from the LiOH solution.

[0130] In some examples, in 308, depending on the concentrations of calcium, magnesium, and other polyvalent cations, a second ion exchange treatment may be used to remove and further purify the calcium, magnesium, and other polyvalent cations using one or more resins. Any suitable resin for the removal of divalent ions may be employed in the ion exchange treatment 308 for the removal of calcium, magnesium, and other polyvalent cations. In some examples, the ion exchange treatment 308 may include, but is not limited to, the use of a weakly acidic cationic resin, such as a resin having carboxyl functional groups, like a polyacrylate microporous resin. By the ion exchange treatments 306 and 308, a purified LiOH solution can be obtained in this manner.

[0131] In some cases, the purified LiOH solution may be treated to obtain lithium hydroxide monohydrate with a low carbonate content, as previously described with reference to Figure 1.

[0132] In some cases, the purified LiOH solution can be concentrated at 310. As previously described, in some cases, concentration can be achieved by evaporation. In some cases, evaporation can be carried out at temperatures in the range of approximately 110–120°C. In some cases, concentration can be carried out under atmospheric pressure using any suitable equipment. In some cases involving multiple evaporation steps or under vacuum, the temperature range can be in the range of approximately 30–120°C. In some cases, evaporation may involve heating the purified LiOH solution produced at 308 to its boiling point and evaporating it until saturation of lithium hydroxide monohydrate in the concentrated solution is reached, or just before saturation is reached, as previously described. As a result of this concentration step, solid impurities containing Li2CO3 may precipitate by the following mechanism. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…)+yOH - (aqueous solution)→ M x OH y (Solid) or SiO2 (Solid) Li2CO3 (aqueous solution) → Li2CO3 (solid)

[0133] In some examples, solid-liquid separation may be performed in 312 after concentration is complete in 310. As previously described, solid-liquid separation may be performed by any suitable means. In some examples, solid-liquid separation may involve using one or more filters, thickeners, centrifuges, or any combination of different solid-liquid separation techniques. In some examples, the solid separated from 310 may be recycled to 302 so that the precipitated Li2CO3 can dissolve again to produce more LiOH. In some examples, this recycling may facilitate the recovery of lithium during the process. In some examples, the accumulation of recycled impurities during the process may be controlled by stopping evaporation when lithium hydroxide monohydrate is saturated or just before it reaches saturation, and removing the formed impurities before the crystallization of lithium hydroxide monohydrate can proceed. Other methods may also be employed.

[0134] In some cases, some calcium hydroxide may remain in the concentrated LiOH solution. In some cases, calcium hydroxide can be removed by employing an ion exchange treatment in 314 before solid-liquid separation of the crystallized lithium hydroxide monohydrate. In some cases, the ion exchange treatment may involve the use of one or more resins to convert calcium hydroxide in the solution to calcium chloride (CaCl2). Any suitable resin for the removal of divalent ions can be employed in the ion exchange treatment 314. In some cases, the ion exchange treatment 314 may include, but is not limited to, the use of a weakly acidic cationic resin, such as a resin having a carboxyl functional group, like a polyacrylate microporous resin. Due to the high solubility of calcium chloride in water, in some cases, calcium chloride can be removed during solid-liquid separation of the crystallized lithium hydroxide monohydrate by employing a step of washing the filtered lithium hydroxide monohydrate solid or cake with pure water.

[0135] In 316, after the ion exchange treatment in 314, the saturated lithium hydroxide monohydrate in the concentrated solution may crystallize. In some examples, crystallization can be achieved by restarting the concentration process and continuing evaporation, as described above, or by cooling crystallization. When using cooling crystallization, the final cooling temperature can be approximately 23°C to 40°C. In some examples, crystallization follows the following mechanism. LiOH (aqueous solution) + H2O → LiOH*H2O (solid)

[0136] In 318, the crystallized lithium hydroxide monohydrate salt can be removed from the solution by any suitable solid-liquid separation. In some examples, the solid-liquid separation may be carried out using one or more hydrocyclones in combination with one or more centrifuges. In some examples, in 318, the solid-liquid separation may include washing the resulting filter cake. In some examples, as described above, the washing step may be carried out using pure water to remove calcium chloride formed during the ion exchange treatment in 314. In some examples, the residual water content in the lithium hydroxide monohydrate after solid-liquid separation may be in the range of about 1-5% based on the total mass of the cake. In some examples, the resulting lithium hydroxide monohydrate is lithium hydroxide monohydrate with a low carbonate content.

[0137] In some cases, the remaining LiOH solution after removing lithium hydroxide monohydrate salt in 318 can be recycled to 310. Recirculating this residue can reduce lithium loss in process 300. In some cases, a portion of the liquid can be purged to prevent the accumulation of impurity concentrations in the process.

[0138] In some examples, at 320, optional purification of the crystallized lithium hydroxide monohydrate may be carried out by one or more redissolution and recrystallization steps, and / or one or more additional reslurrying and filtration steps, until the product meets the specifications of the desired battery grade.

[0139] In some cases, once the final purified lithium hydroxide monohydrate salt is obtained, it may be sent to one or more drying and packaging steps in 322.

[0140] In some cases, process 300 may be carried out in an atmosphere that contains little to no CO2 in order to keep CO2 absorption from the air as low as possible.

[0141] Figure 3B shows a process 330 similar to that described with reference to Figure 3A, except that the carbonate is removed by caustic treatment, which involves adding calcium hydroxide before solid-liquid separation of the crystallized lithium hydroxide monohydrate, instead of ion exchange treatment before concentration of the LiOH solution.

[0142] In some examples, in steps 332 and 334, crude lithium carbonate may be dissolved by a leaching process using calcium hydroxide, followed by a similar solid-liquid separation in steps 302 and 304 with reference to process 300, to obtain a LiOH solution with residual water content in the range of 40–70% after solid-liquid separation. In some examples, if a LiOH solution is provided as the starting lithium feed instead of lithium carbonate in process 330, the dissolution and separation in steps 332 and 334 may be omitted. Any LiOH solution may be used as the starting material. In some examples, the provided LiOH solution may be a crude LiOH solution, a technical grade LiOH solution, an industrial grade LiOH solution, a primary grade LiOH solution, a battery grade LiOH solution, or any mixture thereof. In some examples, additional LiOH solution may be optionally added to the LiOH solution produced in step 334 in step 336, or immediately before step 336.

[0143] In some examples, in 336, the LiOH solution obtained in 334 may be subjected to ion exchange to remove calcium, magnesium, and other polyvalent cations in a manner similar to that described earlier with reference to process 300 in 308. In some examples, the LiOH solution produced in 334 may be purified in 336 using this ion exchange treatment which uses a resin capable of removing or configured to remove calcium, magnesium, and other polyvalent cations.

[0144] In some examples, the purified LiOH solution in 338 may be optionally concentrated. In some examples, concentration may be by evaporation. In some examples, evaporation may be performed to remove a desired amount of water from the solution before achieving saturation or near-saturation of lithium hydroxide monohydrate. In some examples, the LiOH solution in 338 may be concentrated by removing up to one-third of the water from the solution, up to one-half of the water from the solution, or in the range of one-third to one-half of the water from the solution.

[0145] In some examples, after reaching the desired concentration level at 338, the concentrated LiOH solution may be optionally caustized at 340 by the addition of calcium hydroxide. In some examples, caustization may be carried out by adding an excess amount of calcium hydroxide, e.g., 10-30%, to promote the precipitation of calcium carbonate by increasing the calcium concentration in the solution. In some examples, the temperature may be kept constant throughout this process. This process may make it possible to remove or reduce the lithium carbonate present in the concentrated LiOH solution. In some examples, a solid calcium carbonate and an additional aqueous lithium hydroxide solution may be formed in this process. Ca(OH)2(solid)+Li2CO3(aqueous solution)= CaCO3 (solid) + 2LIOH (aqueous solution)

[0146] In some cases, calcium carbonate solids may precipitate from the solution. In some cases, an aqueous lithium hydroxide solution may increase the concentration of the solution.

[0147] In some examples, at 342, the causticated LiOH solution may be optionally separated into solid and liquid to remove any remaining lithium carbonate and calcium carbonate formed at 340. In some examples, at 342, this process may also precipitate metallic impurities introduced by the addition of Ca(OH)2, as well as any excess Ca(OH)2 and some silica that may be present in the solution. In some examples, solid and liquid separation may be carried out by any suitable means. In some examples, solid and liquid separation may involve using one or more filters, thickeners, centrifuges, or any combination of different solid and liquid separation techniques. In some examples, the solid separated from 342 may be recycled back into 332 so that the precipitated Li2CO3 can dissolve again to produce more LiOH. In some examples, this recycling may facilitate the recovery of lithium during the process.

[0148] In some cases, the solid calcium carbonate cake separated from the caustic LiOH solution may have residual moisture ranging from 40 to 70% based on the total mass of the cake.

[0149] In some examples, the LiOH solution produced in 342 may be optionally further purified in 344. In some examples, the purification may be a softening process. In some examples, the purification may include an ion exchange treatment using one or more resins capable of removing calcium, magnesium, and other polyvalent cations. In some examples, the LiOH solution produced in 342 may be ion-exchanged in 344 to remove calcium, magnesium, and other polyvalent cations in a manner similar to that described earlier in 308 with reference to process 300.

[0150] In some cases, the further purified LiOH provided in 344 may be used to form low-carbonate, battery-grade lithium hydroxide monohydrate, as previously described with reference to Figure 1.

[0151] In some examples, the purified LiOH solution produced in 344 may be used further, or if steps 338 to 344 are not performed, the purified LiOH solution produced in 336 may be used to form lithium hydroxide monohydrate. In some examples, the LiOH solution from 336 or 344 may be concentrated in 346. As previously described, in some examples, concentration may be achieved by evaporation. In some examples, evaporation may be carried out at a temperature in the range of about 110–120°C. In some examples, concentration may be carried out under atmospheric pressure using any suitable equipment. In some examples involving multiple evaporation steps or under vacuum, the temperature range may be in the range of about 30–120°C. In some examples, the evaporation may include heating the LiOH solution produced in 336 or 344 to its boiling point and evaporating it until the lithium hydroxide monohydrate in the concentrated solution is saturated, or just before saturation, as previously described. As a result of this concentration step, solid impurities containing Li2CO3 may precipitate by the following mechanism. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…)+yOH - (aqueous solution)→ M x OH y (Solid) or SiO2 (Solid) Li2CO3 (aqueous solution) → Li2CO3 (solid)

[0152] In some examples, solid-liquid separation may be performed in 348 after concentration is complete in 346. As previously mentioned, solid-liquid separation may be performed by any suitable means. In some examples, solid-liquid separation may involve using one or more filters, thickeners, centrifuges, or any combination of different solid-liquid separation techniques. In some examples, the solid separated from 346 may be recycled to 332 so that the precipitated Li2CO3 can dissolve again to produce more LiOH. In some examples, this recycling may facilitate the recovery of lithium during the process. In some examples, the accumulation of recycled impurities during the process may be controlled by stopping evaporation when lithium hydroxide monohydrate is saturated or just before it reaches saturation, and removing the formed impurities before the crystallization of lithium hydroxide monohydrate can proceed. Other methods may also be employed.

[0153] In 350, the saturated lithium hydroxide monohydrate in the concentrated solution may crystallize. In some cases, as described above, crystallization can be achieved by restarting the concentration process and continuing evaporation, or by cooling crystallization. When using cooling crystallization, the final cooling temperature can be approximately 23°C to 40°C. In some cases, crystallization follows the following mechanism. LiOH (aqueous solution) + H2O → LiOH*H2O (solid)

[0154] In 352, the crystallized lithium hydroxide monohydrate salt can be removed from the solution by any suitable solid-liquid separation. In some examples, the solid-liquid separation can be carried out using one or more hydrocyclones in combination with one or more centrifuges. In some examples, the residual water content in the lithium hydroxide monohydrate after solid-liquid separation can be in the range of about 1-5%. In some examples, the lithium hydroxide monohydrate produced is a lithium hydroxide monohydrate with a low carbonate content.

[0155] In some cases, the remaining LiOH solution after removing lithium hydroxide monohydrate salt in 352 can be recycled to 342. Recirculating this residue can reduce lithium loss in process 330. In some cases, a portion of the liquid can be purged to prevent the accumulation of impurity concentrations within the process.

[0156] In some examples, in 354, optional purification of the crystallized lithium hydroxide monohydrate may be carried out by one or more redissolution and recrystallization steps, and / or one or more additional reslurrying and filtration steps, until the product meets the specifications of the desired battery grade.

[0157] In some cases, once the final purified lithium hydroxide monohydrate salt is obtained, it may be sent to one or more drying and packaging steps in 356.

[0158] In some cases, process 330 may be carried out in an atmosphere that contains little to no CO2 in order to keep CO2 absorption from the air as low as possible.

[0159] In some examples, processes 300 and 330, as described with reference to Figures 3A and 3B, can be modified by starting with supplying a LiOH solution instead of a lithium carbonate feed. In some examples, if a LiOH solution is provided, it is not necessary to produce a LiOH solution from a lithium carbonate feed. In some examples, processes 300 and 330 can be carried out in the same manner as described above, except that the dissolution of lithium carbonate with an alkaline earth hydroxide such as calcium hydroxide and the separation of precipitated alkaline earth carbonates such as calcium carbonate at the start of each process (i.e., steps 302 and 304 of process 300 and steps 332 and 334 of process 330) are omitted, respectively.

[0160] Figure 4 shows an example process flow diagram for producing battery-grade low-carbonate lithium hydroxide monohydrate, starting from a lithium feedstock of either lithium carbonate or an aqueous lithium chloride solution. In some examples where the lithium feedstock is lithium carbonate, the process may involve dissolving the lithium carbonate using an acid. In some examples, the acid used may be hydrochloric acid (HCl). In some examples where the lithium feedstock is an aqueous lithium chloride solution, the process may involve adding an acid such as hydrochloric acid to lower the pH of the solution, and then heating the solution to remove the carbonate as CO2, as described below. In some examples, regardless of the starting lithium feedstock, the process may involve generating a LiOH solution by an electrolysis / electrodialysis step.

[0161] In some examples, process 400 shown in Figure 4 may include providing a lithium feedstock in 402.

[0162] In some examples, the lithium feed may include lithium carbonate, such as a feed of crude lithium carbonate. In this case, in 402, the dissolution of crude lithium carbonate may be carried out by contacting the lithium carbonate with an excess of HCl. In some examples, the excess amount of HCl can be provided in the range of approximately 0-10%. In some examples, this dissolution may be carried out in a continuous stirred-tank reactor. In some examples, this dissolution may be carried out under atmospheric pressure. In some examples, the dissolution may be carried out at a temperature in the range of 70°C to 90°C. In some examples, the dissolution mechanism may follow the following equation. Li2CO3 (solid) + 2HCl (aqueous solution) → 2LiCl (aqueous solution) + CO2 (gas) + H2O

[0163] In some cases, an aqueous solution of LiCl is obtained by a dissolution process. It has been found that the solubility of CO2 is kept low depending on the temperature at which the solution is maintained during this dissolution process.

[0164] In some examples, the lithium feed supplied in process 400 may be an aqueous lithium chloride solution instead of a lithium carbonate feed. In some examples, the lithium feed may include crude lithium chloride, technical grade lithium chloride, industrial grade lithium chloride, primary grade lithium chloride, battery grade lithium chloride, lithium chloride with impurities, or any combination thereof. In some examples where an aqueous lithium chloride solution is supplied as the lithium feed, the process may proceed to 404 instead of 402. In some examples, in 402, hydrochloric acid may be added to the aqueous lithium chloride solution to lower the pH, and the resulting solution may then be heated to about 70-90°C to remove, reduce, and / or reduce the carbonate as CO2. Thus, the solution obtained in 404 is obtained in 402 It can be similar to what is obtained by dissolving crude Li2CO3.

[0165] In some cases, a lithium chloride solution obtained by dissolving lithium carbonate in 402, or by heating and pH adjustment in 404, can be purified. In some cases, impurities in the lithium chloride solution can be precipitated in 406 by adding hydroxide. In some cases, the hydroxide may be NaOH or Ca(OH)2. In some cases, the hydroxide may react with the impurities according to the following formula. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…)+yOH - (aqueous solution)→ M x OH y (Solid) or SiO2 (Solid)

[0166] In some examples, prior to introduction at 406, the sodium hydroxide solution at 408 may be optionally purified using an ion exchange resin capable of removing carbonates or configured to remove carbonates.

[0167] In some cases, a purified lithium chloride solution can be obtained by removing the solid precipitated when hydroxide is added to the lithium chloride solution in 410 and 406. In some cases, the solid can be removed by solid-liquid separation. In some cases, any suitable solid-liquid separation method can be used. In some cases, solid-liquid separation can be performed by filtration and / or centrifugation.

[0168] In some cases, the purified lithium chloride solution from 410 may undergo further purification to remove calcium, magnesium, and other polyvalent cations, as well as / or carbonates and / or sulfates.

[0169] In some examples, at 412, a purified lithium chloride solution from 410 may be subjected to ion exchange treatment using a resin capable of removing, or configured to remove, calcium, magnesium, and other polyvalent cations. In some examples, the ion exchange treatment at 412 may include, but is not limited to, the use of a weakly acidic cationic resin, such as a resin having carboxyl functional groups, like a polyacrylate microporous resin.

[0170] In some examples, in 414, a further purified lithium chloride solution from 412 may be treated by ion exchange using a resin capable of removing or configured to remove carbonates and / or sulfates. In some examples, the ion exchange treatment in 414 may involve the use of any suitable resin, in some examples the resin may include a styrene resin as a polystyrene-divinylbenzene resin.

[0171] Once the lithium chloride solution is sufficiently purified by one or more steps of 410, 412, and 414, it can be used to form lithium hydroxide monohydrate.

[0172] In some cases, the purified lithium chloride solution can be concentrated at 416. In some cases, the concentrated solution may have a lithium chloride concentration ranging from approximately 4 wt% to approximately 13 wt%. In some cases, the concentration step may include reverse osmosis (RO). In some cases, the concentration step may include evaporation. In some cases, RO can be performed at room temperature under osmotic pressure. The concentration achieved may depend on the applied osmotic pressure. In some cases, evaporation can be used to concentrate the solution to saturation over a variable temperature range. In some cases, evaporation may provide greater control over the concentration step.

[0173] In some cases, at 418, a concentrated lithium chloride solution can be converted to a lithium hydroxide solution via an electrolysis / electrodialysis process. In this way, a concentrated LiOH solution can be obtained at 418.

[0174] In some cases, at 420, the LiOH solution may be further concentrated to obtain a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate. As previously described, in some cases, concentration may be achieved by evaporation. In some cases, evaporation may be carried out at temperatures in the range of about 110–120°C. In some cases, concentration may be carried out under atmospheric pressure using any suitable equipment. In some cases involving multiple stages of evaporation or under vacuum, the temperature range may be in the range of about 30–120°C. In some cases, the evaporation may involve heating the concentrated LiOH solution produced at 418 to its boiling point and evaporating it until saturation of lithium hydroxide monohydrate in the concentrated solution is reached, or just before saturation is reached, as previously described. As a result of this concentration step, solid impurities containing Li2CO3 may precipitate by the following mechanism. x(M=Fe,Al,Co,Cu,Ni,Mn,Zn,As,…)+yOH - (aqueous solution)→ M x OH y (Solid) or SiO2 (Solid) Li2CO3 (aqueous solution) → Li2CO3 (solid)

[0175] In some examples, solid-liquid separation may be performed in 422 after concentration is complete in 420. As previously mentioned, solid-liquid separation may be performed by any suitable means. In some examples, solid-liquid separation may involve using one or more filters, thickeners, centrifuges, or any combination of different solid-liquid separation techniques. In some examples, the solid separated from 422 may be recycled to 402 so that the precipitated Li2CO3 can be redissolved to produce more LiCl and ultimately more LiOH. In some examples, this recycling may facilitate the recovery of lithium during the process. In some examples, the accumulation of recycled impurities during the process may be controlled by stopping evaporation when lithium hydroxide monohydrate is saturated or just before saturation is reached and removing the formed impurities before the crystallization of lithium hydroxide monohydrate can proceed. Other methods may also be employed.

[0176] In some cases, in 424, saturated lithium hydroxide monohydrate in a concentrated LiOH solution can crystallize. In some cases, as described above, crystallization can be achieved by a concentration evaporation process or by cold crystallization. When using cold crystallization, the final cooling temperature can be approximately 23°C to 40°C. In some cases, crystallization follows the following mechanism. LiOH (aqueous solution) + H2O → LiOH*H2O (solid)

[0177] In 426, the crystallized lithium hydroxide monohydrate salt can be removed from the solution by any suitable solid-liquid separation. In some examples, the solid-liquid separation can be carried out using one or more hydrocyclones in combination with one or more centrifuges. In some examples, the residual water content in the lithium hydroxide monohydrate cake after solid-liquid separation can be in the range of about 1-5% based on the total mass of the cake. In some examples, the lithium hydroxide monohydrate produced is lithium hydroxide monohydrate with a low carbonate content.

[0178] In some cases, the remaining LiOH solution after removing lithium hydroxide monohydrate salt in 424 can be recycled to the concentration step in 416. Recirculating this residue can reduce lithium loss in process 400. In some cases, a portion of the liquid can be purged to prevent the accumulation of impurity concentrations within the process.

[0179] In some examples, in 428, optional purification of the crystallized lithium hydroxide monohydrate may be carried out by one or more redissolution and recrystallization steps, and / or one or more additional reslurrying and filtration steps, until the product meets the specifications of the desired battery grade.

[0180] In some cases, once the final purified lithium hydroxide monohydrate salt is obtained, it may be sent to one or more drying and packaging stages at 430°C.

[0181] In some cases, process 400 may be carried out in an atmosphere that contains little to no CO2 in order to keep CO2 absorption from the air as low as possible.

[0182] One or more of the purification steps in process 400 described above can be omitted depending on the level of impurities in the system and the concentration of the lithium chloride solution.

[0183] In some examples, as described above with reference to Figures 1-4, the liquid generated during any of the solid-liquid separations described can be recycled back into the respective processes.

[0184] In some examples, the systems described herein may include one or more control systems, sensors, and other standard components that enable their control and operation.

[0185] In some examples, although not illustrated, the systems described herein may include one or more sensors commonly used in the art. In some examples, the sensors may be used to monitor the operation of the described systems. Non-limiting examples of one or more sensors may include temperature sensors, pressure sensors, flow meters, pH meters, and other similar sensors.

[0186] In some examples, though not shown, one or more control systems may include one or more controllers and / or other suitable computing devices to control one or more parts of the systems described herein. A controller may include one or more processors and memory coupled to communicate with one another. In the illustrated examples, memory may be used to store logical instructions for operating and / or controlling and / or monitoring the operation of the described processes. In some examples, a controller may include or be coupled to input / output devices such as a monitor, keyboard, speaker, microphone, and computer mouse. In some examples, one or more controllers may also include one or more communication components, or similar structures, such as transceivers, to enable wired and / or wireless communication. In some examples, this enables remote operation of one or more systems described herein.

[0187] In some examples, memory associated with one or more controllers and / or other suitable computing devices may be non-temporary computer-readable media. The memory may store an operating system and one or more software applications, instructions, programs, and / or data in order to implement the functions attributed to the methods described herein and various systems. In some embodiments, the memory may be implemented using any suitable memory technology, such as static random-access memory (SRAM), synchronous dynamic RAM (SDRAM), non-volatile / flash memory, or any other type of memory capable of storing information. The control system may include any number of logical components, program components, and physical components.

[0188] A logical instruction may contain one or more software modules and / or other sufficient information for autonomous driving, safety procedures, and routine maintenance processes. Any operation of the described system may be implemented in hardware, software, or a combination thereof. In the context of software, an operation represents a computer-executable instruction stored on one or more computer-readable storage media, which, when executed by one or more processors, performs the operation described. Generally, computer-executable instructions may include routines, programs, objects, components, data structures, etc., that perform one or more functions or implement a particular abstract data type.

[0189] It will be apparent to those skilled in the art that various modifications and changes can be made to this disclosure without departing from the spirit or scope of this disclosure. Accordingly, this disclosure is intended to include modifications and changes to this disclosure insofar as they remain within the scope of the appended claims and their equivalents.

Claims

1. A process for producing lithium hydroxide monohydrate, Forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate, From the concentrated lithium hydroxide solution, at least a portion of the lithium carbonate is removed through a first solid-liquid separation step. To crystallize the lithium hydroxide monohydrate in the concentrated lithium hydroxide solution, The crystallized lithium hydroxide monohydrate is separated from the concentrated lithium hydroxide solution in a second solid-liquid separation step. A process that includes this.

2. The process according to claim 1, further comprising forming the concentrated lithium hydroxide solution and providing a lithium-containing feedstock.

3. The process according to claim 2, wherein the provision of the lithium-containing feed comprises providing a lithium hydroxide solution, the lithium hydroxide solution comprising crude lithium hydroxide, technical grade lithium hydroxide, industrial grade lithium hydroxide, battery grade lithium hydroxide, primary grade lithium hydroxide, lithium hydroxide containing impurities, or any combination thereof.

4. The process according to claim 2, wherein providing the lithium-containing feed comprises providing lithium carbonate, wherein the lithium carbonate includes crude lithium carbonate, technical grade lithium carbonate, industrial grade lithium carbonate, primary grade lithium carbonate, battery grade lithium carbonate, impurity-containing lithium carbonate, or any combination thereof.

5. A process according to claim 4, further comprising dissolving the lithium carbonate to obtain a lithium hydroxide solution.

6. The process according to claim 5, wherein the dissolution comprises reacting the lithium carbonate with an acid or an alkaline earth hydroxide.

7. The process according to claim 6, wherein the dissolution includes reacting the lithium carbonate with an acid containing sulfuric acid to produce a lithium sulfate solution.

8. A process according to claim 7, further comprising reacting the lithium sulfate solution with a hydroxide to form a lithium hydroxide solution.

9. The process according to claim 8, wherein the hydroxide comprises sodium hydroxide, and the process is To produce an aqueous sodium sulfate solution, The process involves performing cooling crystallization to crystallize the aqueous sodium sulfate solution and obtain Glauber's salt. The Glauber salt is separated from the lithium hydroxide solution via a third solid-liquid separation step to obtain a purified lithium hydroxide solution. A process that further includes this.

10. A process according to claim 9, wherein forming a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate is a process of concentrating the purified lithium hydroxide solution.

11. A process according to claim 10, wherein the process of concentrating the purified lithium hydroxide solution includes an evaporation step.

12. The process according to claim 8, wherein the hydroxide comprises barium hydroxide, and the process is To produce solid barium sulfate, A process further comprising separating the solid barium sulfate from the lithium hydroxide solution via a second solid-liquid separation step to obtain a purified lithium hydroxide solution.

13. A process according to claim 10 or 12, wherein forming the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate is a process of concentrating the purified lithium hydroxide solution.

14. A process according to claim 13, wherein the process of concentrating the purified lithium hydroxide solution includes an evaporation step.

15. The process according to claim 6, wherein the dissolution includes reacting the lithium carbonate with an alkaline earth hydroxide to form a lithium hydroxide solution.

16. The process according to claim 15, wherein the alkaline earth hydroxide comprises calcium hydroxide, and the process is The process involves reacting the calcium hydroxide in the lithium hydroxide solution to form solid calcium carbonate, A process comprising removing the solid calcium carbonate via a third solid-liquid separation.

17. The process according to claims 3 to 16, A process further comprising ion exchange treatment of the lithium hydroxide solution to obtain a purified lithium hydroxide solution.

18. The process according to claim 17, wherein the ion exchange is A process comprising contacting the lithium hydroxide solution with a first resin capable of removing carbonates, sulfates, or both; and then optionally contacting the lithium hydroxide solution with a second resin capable of removing calcium, magnesium, polyvalent cations, or a combination thereof.

19. A process according to claim 20, wherein forming the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate is a process of concentrating the purified lithium hydroxide solution.

20. A process according to claim 19, further comprising: removing at least a portion of lithium carbonate by ion exchange before crystallizing the lithium hydroxide monohydrate; and then purifying the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate by contacting the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate with a third resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof.

21. A process according to claim 17, comprising a first ion exchange treatment, which includes contacting the lithium hydroxide solution with a first resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof.

22. The process according to claim 21, Concentrating the purified lithium hydroxide solution, The concentrated lithium hydroxide solution is brought into contact with calcium hydroxide and reacted with the present lithium carbonate to form a calcium carbonate solid and an additional aqueous lithium hydroxide solution. The formation of calcium carbonate and at least a portion of the remaining lithium carbonate are removed by a fourth solid-liquid separation, A process that further includes this.

23. The process according to claim 22, further comprising purifying the lithium hydroxide solution by a second ion exchange treatment after the fourth solid-liquid separation, wherein the second ion exchange treatment comprises contacting the lithium hydroxide solution with a second resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof to obtain a purified lithium hydroxide solution. A process comprising concentrating the lithium hydroxide solution after the second ion exchange treatment by an evaporation step to form the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate.

24. The process according to claim 21, wherein the concentrated lithium hydroxide solution is saturated or nearly saturated with lithium hydroxide monohydrate, A process comprising concentrating the purified lithium hydroxide solution by an evaporation step.

25. The process according to claim 2, wherein the provision of the lithium-containing feed comprises providing a lithium sulfate solution.

26. A process according to claim 25, further comprising reacting the lithium sulfate solution with a hydroxide.

27. The process according to claim 26, wherein the hydroxide is sodium hydroxide, To produce an aqueous sodium sulfate solution, The cooling and crystallization process is performed to crystallize the aqueous sodium sulfate solution and obtain Glauber's salt. The Glauber salt is separated from the lithium hydroxide solution via a third solid-liquid separation step to obtain a purified lithium hydroxide solution. A process that further includes this.

28. The process according to claim 26, wherein the hydroxide comprises barium hydroxide, The production of solid barium sulfate, The solid barium sulfate is separated from the lithium hydroxide solution via a second solid-liquid separation step to obtain a purified lithium hydroxide solution. A process that further includes this.

29. A process according to claim 27 or 28, wherein forming the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate is a process of concentrating the purified lithium hydroxide solution.

30. A process according to claim 29, wherein the process of concentrating the lithium hydroxide solution includes an evaporation step.

31. The process according to claim 2, wherein the provision of the lithium-containing feed comprises providing lithium chloride, wherein the lithium chloride includes crude lithium chloride, technical grade lithium chloride, industrial grade lithium chloride, primary grade lithium chloride, battery grade lithium chloride, lithium chloride containing impurities, or any combination thereof.

32. A process according to claim 31, further comprising contacting the lithium-containing feed with hydrochloric acid to raise the temperature of the solution to obtain a lithium chloride solution.

33. The process according to claim 6, wherein the dissolution includes reacting the lithium carbonate with an acid containing hydrochloric acid to form a lithium chloride solution.

34. A process according to claim 32 or 33, further comprising contacting the lithium chloride solution with a hydroxide.

35. The process according to claim 34, wherein the hydroxide is selected from sodium hydroxide or calcium hydroxide.

36. A process according to claim 35, further comprising removing precipitates from the lithium chloride solution after contact with the hydroxide by a third solid-liquid separation step.

37. A process according to claim 36, further comprising purifying the lithium chloride solution after the third solid-liquid separation step to obtain a purified lithium chloride solution.

38. The process according to claim 37, wherein the lithium chloride solution is purified A first purification by first ion exchange, which includes contacting the lithium chloride solution with a first resin capable of removing calcium, magnesium, polyvalent cations, or combinations thereof, A process comprising: a second purification including a second ion exchange, which involves contacting the first purified lithium chloride solution with a second resin capable of removing carbonates, sulfates, or both.

39. A process according to claim 37, further comprising concentrating the purified lithium chloride solution to obtain a concentrated lithium chloride solution.

40. A process according to claim 39, wherein concentrating the purified lithium chloride solution comprises reverse osmosis, evaporation, or both.

41. The process according to claim 39, further comprising converting the concentrated lithium chloride solution into the concentrated lithium hydroxide solution by electrolysis, electrodialysis, or both, A process comprising forming the concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate, and further concentrating the concentrated lithium hydroxide solution formed by electrolysis, electrodialysis, or both.

42. A process according to claim 1, wherein crystallizing the lithium hydroxide monohydrate includes further concentrating the concentrated lithium hydroxide solution by evaporation.

43. A process according to claim 1, wherein the crystallization of the lithium hydroxide monohydrate includes cooling crystallization.

44. A process according to claim 43, comprising performing an evaporation step to form a concentrated lithium hydroxide solution saturated or nearly saturated with lithium hydroxide monohydrate.

45. A process according to claim 44, further comprising using a heat pump arranged to provide cooling for the cooling crystallization and heating for the evaporation step.

46. The process according to claim 1, further comprising one or more purifications of the crystallized lithium hydroxide monohydrate separated from the concentrated lithium hydroxide solution.

47. A process according to claim 1, further comprising drying and packaging the crystallized lithium hydroxide monohydrate separated from the concentrated lithium hydroxide solution.

48. A process according to claim 1, further comprising separating the crystallized lithium hydroxide monohydrate and then recirculating the concentrated lithium hydroxide solution to produce further lithium hydroxide monohydrate.

49. Lithium hydroxide monohydrate formed by the process described in any one of claims 1 to 48, wherein the lithium hydroxide monohydrate contains less than 2000 ppm of lithium carbonate.

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