Process and product

Abstract

A process for preparing a lithium manganese oxide sorbent, the process comprising: providing a solid / solid mixture of a source of manganese and a source of lithium, and heating the mixture to produce a lithium manganese oxide sorbent. Wherein at least one of the source of manganese and the source of lithium is a carbonate. Also described is a lithium manganese oxide sorbent prepared by a process thereof, and a lithium manganese oxide sorbent having a lithium equilibrium capacity of at least about 10 mg / g and superior chemical stability for re- use in lithium extraction process, e.g., for at least 100 cycles.

Description

[0001] PROCESS AND PRODUCT

[0002] TECHNICAL FIELD

[0003] [1] This disclosure relates to a process for preparing a lithium manganese oxide sorbent and a lithium manganese oxide sorbent prepared by the process. This disclosure also relates to a process improvement to the manufacturing of a lithium manganese oxide sorbent at large scale resulting in an improved lithium equilibrium capacity and chemical stability for use in the lithium extraction from lithium solutions. This disclosure also relates to a lithium manganese oxide sorbent having ion exchange properties with a Li / Mn about 0.75 and formula ranging from Lii.3-i.sMni.8-2O4.

[0004] BACKGROUND ART

[0005] [2] Lithium is present naturally in many rocks (such as pegmatites), ocean water, brines, mineral springs and ground waters. Lithium solutions can also be a side product from lithium processing facilities, battery recycling plants, oil well brines, formation waters or other waste or process streams. However, these sources may only contain low concentrations of lithium, for example sea water contains less than 1 ppm of lithium or specific impurities that make the incumbent processes for extracting lithium such as evaporation not viable. Therefore, to be extracted for use, the lithium must be concentrated and / or converted into a useful chemical form.

[0006] [3] Lithium has many uses, but one of the most dominant is the manufacture of batteries, which has high demand due to the growing use of electronics, electric vehicles and storage of renewable energy such as solar power.

[0007] [4] Lithium can be extracted from solution (for example brines) using a sorbent. For example, JPS61247618A describes a method for recovering lithium from geothermal hot water using a lithium manganese oxide sorbent.

[0008] [5] US4,665,049 describes a method for preparation of an absorbent for lithium in an aqueous medium.

[0009] [6] JPS61171535A describes a lithium adsorbent, a method for producing the same, and a method for recovering lithium from a dilute solution using the same.

[0010] [7] However, in order to extract lithium from sources with low concentrations of lithium or in order to make the process commercially useful, the sorbent needs to have a high capacity to absorb lithium. Further, scaling up the production of the sorbent can have negative effects on the lithium equilibrium capacity and stability for re-use in multiple lithium adsorption and desorption cycles in the Direct Lithium Extraction processes (DLE).

[0011] [8] In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

[0012] [9] It is an object of this disclosure to provide a process for preparing a lithium sorbent and / or a lithium sorbent which goes at least some way towards overcoming one or more of the abovementioned problems or difficulties, or to at least provide the industry / public with a useful choice.

[0013] SUMMARY OF THE INVENTION

[0014]

[0010] In a first aspect, the invention provides a process for preparing a lithium manganese oxide sorbent, the process comprising:

[0015] (i) providing a precursor mixture comprising a source of manganese and a source of lithium; and

[0016]

[0011] heating the precursor mixture to produce a lithium manganese oxide sorbent, wherein the precursor mixture is heated at about 300 to 1000°C for about 30 minutes to 48 hours; and wherein at least one of the source of manganese and / or the source of lithium is a carbonate.

[0017]

[0011] In a second aspect, the invention provides a lithium manganese oxide sorbent made by the process of the first aspect.

[0018]

[0012] In a third aspect, the invention provides a lithium manganese oxide sorbent made by the process of the first aspect having a lithium equilibrium capacity of at least about 10 mg / g. In some embodiments, the lithium manganese oxide sorbent made by the process of the first aspect has a lithium equilibrium capacity of at least about 20 mg / g. In some embodiments, the lithium manganese oxide sorbent made by the process of the first aspect has a lithium equilibrium capacity of about 20 to 35 mg / g.

[0019]

[0013] In some embodiments, at least about 40% of the manganese in the lithium manganese oxide sorbent is oxidized to an oxidation state of 4+. In some embodiments, at least about 45%, about 50%, about 55%, about 60%, about 65% or about 70% of the manganese is oxidized to an oxidation state of 4+. In some embodiments, at least about 95% of the manganese in the lithium manganese oxide sorbent is oxidized to an oxidation state of 4+. In some embodiments, about 100% of the manganese in the lithium manganese oxide sorbent is oxidized to an oxidation state of 4+.

[0020]

[0014] In some embodiments, the lithium manganese oxide sorbent comprises manganese with an average oxidation state greater than 3+. In some embodiments, the lithium manganese oxide sorbent comprises manganese with an average oxidation state greater than about 3.1, greater than about 3.2, greater than about 3.3, greater than about 3.4, or greater than about 3.5, greater than about 3.8, greater than about 3.9. In some embodiments, the lithium manganese oxide sorbent comprises manganese with an average oxidation state of about 4.

[0021]

[0015] In some embodiments, the lithium manganese oxide increases in weight by 0 to 9% during the heating as a result of oxygen gain. In some embodiments, the lithium manganese oxide increases in weight by 0.1 to 9% during the heating as a result of oxygen gain. In some embodiments, the oxidation of the lithium manganese oxide sorbent in the calcination is derived from the carbonate precursors.

[0022]

[0016] In some embodiments, the source of lithium is selected from the group consisting of lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide and a combination of any two or more thereof. Preferably, the source of lithium is lithium carbonate.

[0023]

[0017] In some embodiments, the source of manganese is selected from the group consisting of a carbonate, a hydroxide, a nitrate, an oxide and a combination of any two or more thereof. In some embodiments, the source of manganese is manganese carbonate. Preferably, the source of manganese is manganese oxide.

[0024]

[0018] In some embodiments, the source of manganese is selected from the group consisting of MnsC , MnzOs, MnCOs, MnO, Mn(NOs)2, MnOz, Mn(OH)2 and a combination of any two or more thereof.

[0025]

[0019] In some embodiments, the source of manganese is MnsC and the source of lithium is IJ2CO3.

[0026]

[0020] In some embodiments, the source of manganese is a manganese carbonate and the source of lithium is a lithium carbonate.

[0027]

[0021] In some embodiments, the source of lithium is heated with the source of manganese in a lithium : manganese mol ratio of about 0.30 to 1, about 0.40 to 0.95, about 0.50 to 0.90, about 0.60 to 0.85, or about 0.70 to 0.80, or about 0.75. In some embodiments, the source of lithium is heated with the source of manganese in a lithium : manganese mol ratio of about 0.75.

[0028]

[0022] In some embodiments, the source of manganese is a solid.

[0029]

[0023] In some embodiments, the source of manganese is a powder.

[0030]

[0024] In some embodiments, the source of manganese is a loose powder.

[0031]

[0025] In some embodiments, the source of lithium is a solid.

[0032]

[0026] In some embodiments, the source of lithium is a powder.

[0033]

[0027] In some embodiments, the source of lithium is a loose powder.

[0034]

[0028] In some embodiments, the source of manganese and the source of lithium are milled together prior to heating.

[0035]

[0029] In some embodiments, the precursor mixture is heated in a furnace. In some embodiments, the precursor mixture is heated in a static furnace. In some embodiments, the precursor mixture is heated in a furnace in a batch calcination process. In some embodiments, the precursor mixture is heated in a conveyer furnace in a continuous calcination process. In some embodiments, the precursor mixture is heated in a furnace in single calcination process. In some embodiments, the precursor mixture is heated in a furnace in multi step calcination process.

[0030] In some embodiments, the process is a large scale process for preparing a lithium manganese oxide sorbent. In some embodiments, the process is a large scale process for preparing a lithium manganese oxide sorbent, wherein the precursor mixture is heated in an amount of at least about 30 kg. In some embodiments, the precursor mixture is heated in an amount of at least about 50, 60, 70, 80, 90 or 100 kg. In some embodiments, the precursor mixture is heated in an amount of at least about 30 to 2000 kg. In some embodiments, the precursor mixture is heated in an amount of at least about 50 to 1500 kg or about 100 to 1000 kg

[0036]

[0031] In some embodiments, the precursor mixture is heated in a batch process. In some embodiments, the precursor mixture is heated in a batch of at least about 30 kg. In some embodiments, the batch is at least about 50, 60, 70, 80, 90 or 100 kg. In some embodiments, the batch is about 30 to 2000 kg. In some embodiments, the batch is about 50 to 1500 kg or about 100 to 1000 kg. In some embodiments, the batch has a thickness of about 1 to 10 cm. In some embodiments, the batch has a thickness of about 1 to 9 cm, about 2 to 8 cm, about 2 to 7 cm, about 2 to 6 cm or about 3 to 5 cm. In some embodiments, the batch has a thickness of about 3 cm. In some embodiments, the process is carried out with multiple batches at the same time, e.g., multiple trays of the mixture in a single furnace.

[0037]

[0032] In some embodiments, the precursor mixture is heated in a continuous process. In some embodiments, during heating step (ii) in the continuous process, the precursor mixture has a thickness of about 1 to 10 cm. In some embodiments, during heating step (ii) in the continuous process, the precursor mixture has a thickness of about 1 to 9 cm, 2 to 8 cm, 2 to 7 cm, 2 to 6 cm or 3 to 5 cm. In some embodiments, during heating step (ii) in the continuous process, the precursor mixture has a thickness of about 3 cm. In some embodiments, the process is carried out with the precursor mixture placed in a single furnace with a continuous feed and predetermined residence time.

[0038]

[0033] In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 to 20 kg / m2. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 to 15 kg / m2. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 10 to 15 kg / m2. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 kg / m2. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 kg / cm2. In some embodiments, the precursor mixture is heated at a loading capacity of about 10 kg / m2. In some embodiments, precursor the mixture is heated at a loading capacity of about 12 kg / m2. In some embodiments, precursor the mixture is heated at a loading capacity of about 15 kg / m2. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of at least about 5 kg / m2, e.g., at least about 6 kg / m2, 7 kg / m2, 8 kg / m2, 9 kg / m2, 10 kg / m2, 11 kg / m2, 12 kg / m2, 13 kg / m2, 14 kg / m2, 15 kg / m2, 16 kg / m2, 17 kg / m2, 18 kg / m2, 19 kg / m2, 20 kg / m2. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of at least about 10 kg / m2.

[0039]

[0034] In some embodiments, the precursor mixture is heated in a continuous calcination process for a residence time of about 5 to 20 hours. In some embodiments, the precursor mixture is heated in a continuous calcination process for a residence time of about 10 to 15 hours. In some embodiments, the precursor mixture is heated in a continuous calcination process for a residence time of about 5 to 19 hours, 5 to 18 hours, 6 to 17, 6 to 16, 7 to 15, 7 to 14 hours, 8 to 13 hours or 8 to 12 hours. In some embodiments, the precursor mixture is heated in a continuous calcination process for a residence time of about 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 hours.

[0040]

[0035] In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 to 20 kg / m2for a residence time of about 5 to 20 hours. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 10 to 20 kg / m2for a residence time of about 5 to 15 hours. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 to 20 kg / m2for a residence time of about 5 to 20 hours. In some embodiments, the precursor mixture is heated in a continuous calcination process at a loading capacity of at least about 5 kg / m2, e.g., at least about 6 kg / m2, 7 kg / m2, 8 kg / m2, 9 kg / m2, 10 kg / m2, 11 kg / m2, 12 kg / m2, 13 kg / m2, 14 kg / m2, 15 kg / m2, 16 kg / m2, 17 kg / m2, 18 kg / m2, 19 kg / m2, 20 kg / m2for a residence time of about 5 to 15 hours, e.g., about 5 to 19 hours, 5 to 18 hours, 6 to 17, 6 to 16, 7 to 15, 7 to 14 hours, 8 to 13 hours or 8 to 12 hours.

[0041]

[0036] In some embodiments, the process described herein is a process improvement for the calcination of the lithium manganese oxide sorbent, where at least one carbonate-based precursor enables the calcination process to be carried out with no active supply of air.

[0042]

[0037] In some embodiments, the precursor mixture is heated at about 400 to 800°C.

[0043]

[0038] In some embodiments, the precursor mixture is heated at about 450 to 700°C. In some embodiments, the precursor mixture is heated at about 450 to 600°C or about 450 to

[0044] 550°C

[0045]

[0039] In some embodiments, the precursor mixture heated at about 500°C.

[0046]

[0040] In some embodiments, MnsC is heated at about 400 to 800°C with the lithium carbonate.

[0047]

[0041] In some embodiments, the precursor mixture is heated at about 400 to 800°C for about 4 to 12 hours. In some embodiments, the precursor mixture is heated at about 500°C for about 10 hours.

[0042] In some embodiments, manganese oxide is heated at about 450 to 700°C with the source of lithium.

[0048]

[0043] In some embodiments, MnsC is heated at about 450 to 700°C for about 4 to 12 hours with the lithium carbonate.

[0049]

[0044] In some embodiments, MnsC is heated at about 450 to 700°C for about 4 to 8 hours with the lithium carbonate.

[0050]

[0045] In some embodiments, the precursor mixture is heated for about 2 to 24 hours. In some embodiments, the precursor mixture is heated for about 4 to 12 hours.

[0051]

[0046] In some embodiments, the precursor mixture is heated at about 450 to 700°C for about 5 hours.

[0052]

[0047] In some embodiments, MnsC is heated at about 450 to 700°C for about 5 hours with the lithium carbonate.

[0053]

[0048] In some embodiments, step (ii) is performed in a closed vessel. In some embodiments, step (ii) is performed in a static kiln, a fluidized bed or other combustion kiln. In some embodiments, step (ii) is performed in a static kiln. In some embodiments, step (ii) is performed in a continuous kiln. In some embodiments, step (ii) is performed in a conveyer furnace.

[0054]

[0049] In some embodiments, oxygen (e.g. in the form of air, O2 or a mixture of both) is not supplied to the precursor mixture during heating. In some embodiments, oxygen is not actively supplied to the precursor mixture during heating. In some embodiments, oxygen is not passively supplied to the mixture.

[0055]

[0050] In some embodiments the sorbent's capacity and stability in the lithium extraction process is improved when at least one of the source of manganese and the source of lithium is a carbonate-based precursor as compared to a process where a carbonate-based precursor is not used.

[0056]

[0051] In some embodiments, the precursor mixture is heated in a furnace at about 400 to 800 °C. In some embodiments, the precursor mixture is heated in a furnace at about 450 to 700 °C, 450 to 600 °C or 450 to 550 °C. In some embodiments, the precursor mixture is heated in a furnace at about 500 °C.

[0057]

[0052] In some embodiments, the precursor mixture is heated in a furnace for at least about 30 minutes. In some embodiments, the precursor mixture is heated in a furnace for at least about 60 minutes. In some embodiments, the precursor mixture is heated in a furnace for at least about 80 minutes. In some embodiments, step (ii) comprises heating the precursor mixture is heated in a furnace for about 5 to 20 hours, 6 to 19 hours, 6 to 18 hours, 7 to 17 hours, 7 to 16 hours, 8 to 15 hours, 8 to 14 hours, 9 to 13 hours or 9 to 12 hours. In some embodiments, the furnace comprises a continuous kiln with different heating zones. In some embodiments, the furnace comprises a batch kiln with different heating zones. In some embodiments, the furnace comprises a batch kiln with different heating temperature ramps. In some embodiments, the furnace comprises of a conveyor furnace with different heating zones.

[0058]

[0053] In some embodiments, the process provides at least about 80% conversion of the precursor mixture to the lithium manganese oxide sorbent. In some embodiments, the process provides at least about 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90% conversion of the precursor mixture to the lithium manganese oxide sorbent.

[0059]

[0054] In some embodiments, the lithium manganese oxide sorbent comprises a spinel phase. In some embodiments, the lithium manganese oxide sorbent comprises substantially a spinel phase. In some embodiments, the lithium manganese oxide sorbent consists of a spinel phase. In some embodiments, the lithium manganese oxide sorbent consists essentially of a spinel phase.

[0060]

[0055] In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least about 10 mg / g after acid leaching. In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least about 16 mg / g after acid leaching.

[0061]

[0056] In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of about 10 to 50 mg / g after acid leaching.

[0062]

[0057] In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least 10 mg / g once the lithium in the lithium manganese oxide has been leached out. In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least 16 mg / g once the lithium in the lithium manganese oxide has leached out. In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least 10 mg / g, 11 mg / g, 12 mg / g, 13 mg / g, 14 mg / g, 15 mg / g, 16 mg / g, 17 mg / g, 18 mg / g, 19 mg / g, 20 mg / g, 21 mg / g, 22 mg / g, 23 mg / g, 24 mg / g, 25 mg / g, 26 mg / g, 27 mg / g, 28 mg / g, 29 mg / g, 30 mg / g, 31 mg / g, 32 mg / g, 33 mg / g, 34 mg / g or 50 mg / g once the lithium in the lithium manganese oxide has been leached out / activated with acid.

[0063]

[0058] In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of about 10 to 35 mg / g once the lithium in the lithium manganese oxide has leached out.

[0064]

[0059] In some embodiments, the lithium manganese oxide sorbent is in the form of a powder, a pellet or a bead.

[0065]

[0060] In some embodiments, the lithium manganese oxide sorbent is a powder.

[0066]

[0061] In some embodiments, the lithium manganese oxide is in a compacted powder form. In some embodiments the lithium manganese oxide is a loose powder.

[0067]

[0062] In some embodiments, the process further comprises milling the lithium manganese oxide sorbent.

[0063] In some embodiments, the milling step is performed with a ball mill, a ring mill, a bead mill, pulverizer, cement mixer, paddle blender, ribbon blender, and / or any other device able to mix the solid / solid precursor mixture and reduce aggregated particles and / or particle size.

[0068]

[0064] In some embodiments, the lithium manganese oxide sorbent is a powder having an average particle size of less than about 100 microns.

[0069]

[0065] In some embodiments, the source of lithium and the source of manganese are milled separately before being mixed at different mol ratios.

[0070]

[0066] In some embodiments, the precursor mixture is agitated in step (i) to obtain a homogeneous solid-solid mixture of the precursors. In some embodiments, the precursor mixture is optionally agitated at least once during the step (ii) to maintain a homogeneous mixture of the solid-solid mixture of the precursors. In some embodiments, the precursor mixture is milled in step (i) to obtain a homogeneous solid-solid mixture of the precursors. In some embodiments, the precursor mixture is optionally milled at least once during step (ii) to maintain the homogeneous mixture of the solid-solid mixture of the precursors. In some embodiments, the precursor mixture is not agitated while the solids are heated. In some embodiments, the calcination is resumed after the precursor mixture is agitated in step (ii). In some embodiments, the calcination is resumed after the precursor mixture is milled in step (ii).

[0071]

[0067] In some embodiments, the precursor mixture is optionally calcined with more than one calcination steps, where the calcination is resumed after the mixture is agitated at least once during the heating process. In some embodiments, the precursor mixture is not mixed during the calcination step. In some embodiments, the precursor mixture is calcined in one single calcination step. In some embodiments, the precursor mixture is calcined in multiple calcination steps.

[0072]

[0068] In some embodiments, the precursor mixture is heated in a continuous process and is not substantially agitated during heating.

[0073]

[0069] In some embodiments, step (ii) is performed in a furnace, wherein the furnace is optionally opened once during step (ii) and the mixture of the source of manganese and the source of lithium and / or the lithium manganese oxide sorbent are agitated. In some embodiments, step (ii) is performed in a furnace, wherein the furnace is opened twice during step (ii) and the mixture of the source of manganese and the source of lithium and / or the lithium manganese oxide sorbent are agitated. In some embodiments, step (ii) is performed in a furnace, wherein the furnace is opened three times during step (ii) and the precursor mixture and / or the lithium manganese oxide sorbent are agitated. In some embodiments, step (ii) is performed in a furnace, wherein the furnace is not opened during step (ii). In some embodiments, step (ii) is performed in a furnace, wherein the furnace is not opened during step (ii) when at least one of the precursors is a carbonate.

[0070] In some embodiments, the powder having an average particle size of less than about 100 microns is obtained by milling the lithium manganese oxide sorbent. In some embodiments, the lithium manganese oxide sorbent is a powder having an average particle size of less than about 10 microns. In some embodiments, the lithium manganese oxide sorbent is a powder having an average particle size of less than about 1 micron. In some embodiments, the lithium manganese oxide sorbent is a powder having an average particle size of less than about 0.1 microns.

[0074]

[0071] In some embodiments, the lithium manganese oxide sorbent has a lithium / manganese mol ratio of about 0.30 to 1, about 0.40 to 0.95, about 0.50 to 0.90, about 0.60 to 0.85, or about 0.70 to 0.75. In some embodiments, the lithium manganese oxide sorbent has a lithium / manganese mol ratio of about 0.75.

[0075]

[0072] In some embodiments, the process further comprises leaching lithium out of the lithium manganese oxide sorbent.

[0076]

[0073] In some embodiments, the process further comprises leaching lithium out of the lithium manganese oxide sorbent with an acid. In some embodiments, the acid is a mineral acid, such as HCI and / or H2SO4, or weaker acids such as phosphoric or other weak acids. In some embodiments, the sorbent is not substantially dissolved in the process of leaching lithium out of the lithium manganese oxide sorbent.

[0077]

[0074] In some embodiments, the sorbent is not substantially dissolved when leaching lithium out of the lithium manganese oxide sorbent with an acid, e.g, a mineral acid, such as HCI and / or H2SO4, or weaker acids such as phosphoric or other weak acids.

[0078]

[0075] Any of the aforementioned features or embodiments or aspects may be combined with one or more of the other features or embodiments or aspects as described herein.

[0079]

[0076] The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

[0080]

[0077] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[0081]

[0078] As used herein the term "and / or" means "and" or "or", or both.

[0079] As used herein "(s)" following a noun means the plural and / or singular forms of the noun.

[0082]

[0080] The term "lithium : manganese mol ratio" as used in this specification means the ratio of lithium to manganese expressed as a decimal. For example, a lithium : manganese mol ratio of 0.8 equates to a mol ratio of 0.8 mol lithium to 1 mol manganese.

[0083]

[0081] The term "agitating" encompasses processes such as mixing and / or milling. These processes are generally for the purpose of homogenizing a mixture, exposing surface area of a mixture (or its components), reducing aggregated particles of a mixture (or its components) and / or reducing the particle size of a mixture (or its components). Those persons skilled in the art will appreciate other processes may be suitable for such purposes and are encompassed by the term "agitating". Related terms such as "agitated" or "agitation" are to be interpreted in the same manner.

[0084]

[0082] To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

[0085]

[0083] The disclosure consists in the foregoing and also envisages constructions of which the following gives examples only. Features disclosed herein may be combined into new embodiments of compatible components addressing the same or related inventive concepts.

[0086] BRIEF DESCRIPTION OF THE FIGURES

[0087]

[0084] Preferred embodiments of the disclosure will be described by way of example only and with reference to the following drawings.

[0088]

[0085] Figure 1. Lithium adsorption capacity kinetics for sorbent samples prepared using LizCCh / MnsC with a fixed Li / Mn mol ratio of 0.75 with a total calcination time of lOh at different temperatures.

[0089]

[0086] Figure 2. Lithium adsorption capacity kinetics for sorbent samples prepared using LiOH / MnsC with a fixed Li / Mn mol ratio of 0.75 with a total calcination time of lOh at different temperatures.

[0090]

[0087] Figure 3. Lithium adsorption capacity kinetics for sorbent samples prepared using LizCOs / MnCOs with a fixed Li / Mn mol ratio of 0.75 with a total calcination time of lOh at different temperatures.

[0091]

[0088] Figure 4. Lithium adsorption capacity kinetics for sorbent samples prepared using LiOH / MnCCh with a fixed Li / Mn mol ratio of 0.75 with a total calcination time of lOh at different temperatures.

[0092]

[0089] Figure 5. Particle size analysis of sorbent samples calcined in a small batch scale of 100 g and a large batch scale of 30 kg.

[0090] Figure 6. XRD analysis of the calcined sorbent (a) samples 1 and (b) sample 3.

[0093]

[0091] Figure 7. TGA analysis of acid activated sorbent sample 1.

[0094]

[0092] Figure 8. TGA analysis of acid activated sorbent sample 2.

[0095]

[0093] Figure 9. Sorbent recycling test showing the sorbent capacity and chemical stability with its re-use.

[0096]

[0094] Figure 10. Process design of a batch kiln calciner.

[0097]

[0095] Figure 11. Process design of a conveyor kiln calciner.

[0098] DETAILED DESCRIPTION OF THE INVENTION

[0099]

[0096] Described herein is a process for preparing a lithium manganese oxide sorbent, the process comprising heating a precursor mixture of a source of manganese with a source of lithium, wherein at least one of the source of manganese and the source of lithium is a carbonate. Surprisingly, the inventors have discovered that a precursor mixture comprising a manganese carbonate and / or a lithium carbonate is self-oxidizing and, consequently, does not require a source of oxygen during calcination. Therefore, this invention discloses an improved process of preparing lithium manganese oxide sorbent for use in the DLE process. This feature is particularly beneficial for the calcination of the sorbent at large scale (e.g. >30 kg or continuous process with the solids calcined at 5-20 kg / m2). Further, this invention discloses a process of preparing lithium manganese sorbent with improved lithium equilibrium capacity and chemical stability for use in DLE as compared to a process where non-carbonate-based precursors are used. Advantageously, the sorbent calcined in large scale still maintains chemical stability over repeated DLE cycles, e.g., over 100 cycles.

[0100]

[0097] Lithium sorbents may be used to remove lithium from an aqueous medium. The sorbent works by adsorption (upload) of lithium onto the external and / or internal surface of the bulk sorbent. The adsorbed lithium replaces hydrogen in the sorbent, thereby binding the lithium by an ion exchange mechanism.

[0101]

[0098] The solid sorbent can then be separated from the aqueous medium the lithium has been adsorbed from (e.g., a geothermal lithium brine) leaving behind other components (e.g., other salts) as the lithium depleted brine. Lithium can then be recovered by desorption from the sorbent. Desorption (elute or elution), replaces the lithium on / in the sorbent with hydrogen, thereby releasing lithium ions. Desorption may be achieved with an acid wash. The sorbent can then be recovered and re-used for multiple lithium extraction cycles.

[0102]

[0099] A precursor mixture of a source of manganese and a source of lithium is heated to produce the lithium manganese oxide sorbent.

[0103]

[0100] It has also been found that oxygen is required during heating to produce the stable spinel phase LiMnzC , as per example in equation 1. This can be achieved by supplying oxygen to the manganese / lithium mixture during heating, e.g. by active air flow into the reaction vessel. However, actively supplying oxygen to the mixture has practical limitations, particularly for commercial manufacture of the lithium manganese oxide sorbent. For example, the mixture must be sufficiently mixed to ensure all surfaces of the mixture are exposed to oxygen, which can be costly or impractical, particularly for large scale calcination processes (e.g. batches of 30 kg or greater and / or continuous process with the solids calcined at 5-10 kg / cm2). When the solid precursor mixture is agitated, the precursor components may separate due to the difference in density of the precursors (e.g. Mn has a density of 7.5 g / cm3and Li is 0.5 g / cm3), and as a result reduce surface area contact between the source of manganese and the source of lithium. Reduced surface area contact between the components may reduce the efficiency of the calcination process. Additionally, evenly dispersing oxygen within a continuous process, using a conveyer furnace or equivalent, is impractical.

[0104]

[0101] The inventors have discovered that an oxygen supply is not required during heating to produce the stable spinel phase LiMnzC when at least one of the precursors in the mixture comprises a carbonate-based precursor. Preferably, the carbonate precursor is U2CO3. Without wishing to be bound by theory, it is believed this can be explained by a selfoxidizing mechanism, as per equation 2. Advantageously, the use of one or more carbonate precursors removes the need to supply oxygen to the mixture during the calcination. Further the self-oxidizing mechanism, provided by at least one carbonate precursor, requires no or less mixing of the solid mixture compared to precursors that require oxygen. The process improvement described herein is particularly relevant for the calcination of lithium manganese oxide at scale for commercial applications.

[0105] Equation 1 12LiOH + SMn304+ 5O2-> 12LiMn204+ 6H2O Equation 2 Li2CO3+ 4MnC03-> 2LiMn204+ 2CO2+ 3CO

[0106]

[0102] The oxidation state of the lithium sorbent can significantly affect the lithium adsorption-desorption mechanism. Therefore, the calcination condition is a determining step to produce lithium sorbent with high chemical stability and capacity for multiple cycle usage in the process. In equations 3 and 4 are given some examples of the lithium adsorptiondesorption reactions. In equation 3 is shown a sorbent that was not fully oxidized during the calcination as example, resulting in Mn3+ / Mn4+in its chemical structure. For instance, the presence of Mn3+can lead to a surface disproportionation reaction during lithium desorption with acid resulting in a partial dissolution of the sorbent as Mn2+in solution. This indicates a sorbent with poor chemical stability. The square symbol ( □ ) in equation 3 represents vacancy in the chemical structure of the sorbent due to the dissolution of manganese. This phenomenon can be more significantly observed with the sorbent re-use in multiple lithium adsorption and desorption cycles, limiting its application on a commercial scale. (Introduction of manganese based lithium-ion Sieve-A review. In equation 4 is another example with a sorbent calcined where the manganese is fully oxidized to Mn4+, resulting in a sorbent with improved chemical stability and representing an ion exchange mechanism. The sorbent with ion exchange mechanism can be applied in multiple lithium adsorption and desorption cycles, with maintained stability and capacity to extract lithium ions.

[0107] Equation 3

[0108] Equation 4

[0109]

[0103] Therefore, determining the optimum heating conditions and selecting the precursors is crucial to produce a Lithium Manganese Oxide sorbent with superior chemical stability and capacity to adsorb lithium ions from fluids.

[0110]

[0104] Accordingly, in one aspect, the invention provides a process for preparing a lithium manganese oxide sorbent, the process comprising:

[0111] (i) providing a precursor mixture comprising a source of manganese and a source of lithium; and

[0112] (ii) heating the precursor mixture to produce a lithium manganese oxide sorbent, wherein the precursor mixture is heated at about 300 to 1000°C for about 30 minutes to 48 hours; and wherein the precursor mixture is self-oxidizing.

[0113]

[0105] Preferably, the source of lithium and / or the lithium manganese oxide sorbent are agitated as a preparation step prior to calcination. The precursor mixture may be optionally agitated once during heating steps and / or the source of manganese, the source of lithium and / or the lithium manganese oxide sorbent may be agitated during heating steps. Advantageously, the precursor mixture may be heated in one single calcination step and / or the source of manganese, the source of lithium and / or the lithium manganese oxide sorbent may be heated in one single calcination step when at least one of the precursors is a carbonate.

[0114]

[0106] During heating at high temperatures in a closed container, e.g., in a furnace or kiln, oxygen can become diminished. It has been found that allowing oxygen into the heating container may improve the capacity of the resulting sorbent. During heating at high temperatures in a closed container, e.g., in a furnace, oxygen can become diminished. It has been found that actively supplying oxygen into the heating container is not required to improve the capacity and stability of the resulting sorbent when a carbonate precursor is used as explained by a self-oxidizing precursor mixture. This feature is more evident when large calcination batches are calcined (>30 kg, and / or 5-20 kg / m2), whereas the calcination using at least one carbonate-based precursor has shown to significantly improve the sorbent's properties as compared to non-carbonate-based precursors.

[0107] The lithium manganese oxide sorbent prepared according to the invention preferably has a lithium equilibrium capacity of at least about 10 mg / g, more preferably at least about 16 mg / g at ambient temperature. In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of about 10 to 35 mg / g.

[0115]

[0108] In some embodiments, the source of lithium and the source of manganese are heated in a fluidized bed. In some embodiments, the source of lithium and the source of manganese are heated in a static kiln. In some embodiments, the source of lithium and the source of manganese are heated in a continuous kiln. In some embodiments, the source of lithium and the source of manganese are heated in a conveyor kiln. Other suitable apparatus will also be apparent to a person skilled in the art.

[0116]

[0109] Preferably they are both in a solid form, such as a powder, a pellet or a bead. The pellet may be prepared cementing the sorbent particles together with another metal oxide, such as ZrO2 or AI(OH)s, or with an organic polymer, such as polyvinyl chloride (PVC), polyether sulfone (PESU).

[0117] [HO] The source of manganese may be heated, e.g., in a furnace, with the source of lithium at about 300 to l,000°C. For example, the source of manganese may be heated with the source of lithium at about 400 to 800°C, about 450 to 700°C, about 450 to 600°C, about 450 to 550°C, or about 500°C. The source of manganese may be heated with the source of lithium for about 30 minutes to about 48 hours. For example, the source of manganese may be heated with the source of lithium for about 4 to 8 hours, about 4.5 to 7 hours, or about 5 to 6 hours, e.g. for about 5 hours. In some embodiments, the source of manganese is heated at about 450 to 700°C for about 4 to 8 hours, preferably for about 10 hours.

[0118]

[0111] The source of lithium may be, for example but not limited to, lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide or a combination of any two or more thereof. Preferably, the lithium source is lithium carbonate.

[0119]

[0112] The source of manganese may be, for example but not limited to, a carbonate, a hydroxide, a nitrate, an oxide or a combination of any two or more thereof, (i.e. a compound comprising manganese with oxygen alone or with other elements, for example carbon, nitrogen and / or hydrogen). Preferably, the manganese oxide is MnsC .

[0120]

[0113] In some embodiments, the source of manganese is manganese carbonate.

[0121]

[0114] In some embodiments, the source of manganese is selected from the group consisting of MnsC , MnzOs, MnCOs, MnO, Mn(NOs)2, MnC , Mn(OH)2, a Mn organic / inorganic salt with a relatively low thermal decomposition temperature, and a combination of any two or more thereof. Preferably, the source of manganese comprises MnsC and / or is MnCOs.

[0122]

[0115] Preferably, the source of manganese is MnsC and / or is MnCOs and the source of lithium is IJ2CO3. More preferably, the source of manganese is MnsC and the source of lithium is IJ2CO3.

[0116] The source of lithium is heated with the source of manganese preferably in a mol ratio of about 0.30 to 1, about 0.40 to 0.95, about 0.50 to 0.90, about 0.60 to 0.85, or about 0.70 to 0.80. For example, the source of lithium is heated with the source of manganese in a mol ratio of about 0.75 lithium to manganese (i.e., a mol ratio of 0.75 Li to 1 Mn).

[0123]

[0117] The process according to the invention does not require oxygen to be supplied or mixing of the precursors during calcination and, therefore, is particularly advantageous at larger calcination scales. For example, the mixture of the source of manganese and the source of lithium may be heated in a batch of at least about 30 kg. Alternatively, the mixture of the source of manganese and the source of lithium may be heated in a continuous calcination process of at least about 5 kg / cm2. The inventors have also found that the thickness layer of the solids in the calcination is an important aspect of this invention to maintain a homogeneous heat distribution. Those persons skilled in the art will appreciate the improvements of the invention that may be even more beneficial at larger scales, e.g., for batches of at least about 50, 60, 70, 80, 90 or 100 kg. In some embodiments, the batch is about 30 to 2000 kg, about 50 to 1500 kg or about 100 to 1000 kg. In some embodiments, process comprises continuous calcination with the solid precursor mixture using a conveyor at a loading capacity of at least 5 kg / m2,e.g., 5-20 kg / m2preferably at least 10 kg / m2. kg / m2. Advantageously, the process of the present invention enables the use of a continuous process with the precursor mixture at a higher loading capacity than a process without a self-oxidizing precursor mixture.

[0124]

[0118] Accordingly, in another aspect, the invention provides a process for preparing a lithium manganese oxide sorbent on a large scale, the process comprising:

[0125]

[0119] (i) providing a precursor mixture of a source of manganese and a source of lithium; and

[0126]

[0120] (ii) heating the precursor mixture to produce a lithium manganese oxide sorbent, wherein the precursor mixture is heated at about 300 to 1000°C for about 30 minutes to 48 hours; and

[0127]

[0121] wherein at least one of the source of manganese and the source of lithium is a carbonate.

[0128]

[0122] The mixture of the source of manganese and the source of lithium may be heated in a layer, e.g., by heating the mixture in a tray. In these embodiments, preferably, the solids have a thickness of about 1 to 10 cm. In some embodiments, the solids have a thickness of about 1 to 9 cm, about 2 to 8 cm, about 2 to 7 cm, about 2 to 6 cm or about 3 to 5 cm. In some embodiments, the solids have a thickness of about 3 cm. The process may also be carried out with multiple batches at the same time, e.g., multiple trays of the mixture in a single furnace. In some embodiments, the process is carried out with the solid mixture placed in a single furnace with a continuous feed and predetermined residence time. Advantageously, performing the heating step in layers may increase the amount of exposed surface and, consequently, further reduce the need for agitation to expose the solids to heat.

[0129]

[0123] In some embodiments, the precursor mixture and / or the lithium manganese oxide sorbent are not substantially agitated during heating step (ii). For example, preferably the continuous process is carried out without substantial agitation of the precursor mixture and / or the lithium manganese oxide sorbent during heating. Avoiding agitation can be beneficial to reduce or prevent phase separation. When the solid precursor mixture is agitated, the precursor components may separate, e.g. by density, and as a result reduce surface area contact between the source of manganese and the source of lithium. Reduced surface area contact between the components may reduce the efficiency of the calcination process.

[0130]

[0124] The lithium manganese oxide sorbent once formed may be stored in an airtight container, or washed (e.g., with water) and may be dried.

[0131]

[0125] The lithium manganese oxide sorbent produced in the process may optionally be washed with an acid to produce a hydrogen manganese oxide sorbent ready for use (i.e. to exchange the lithium in the sorbent with hydrogen so that it is ready for the lithium upload step, e.g. to activate the sorbent). This is useful when a process for extracting lithium from an aqueous solution containing lithium is first started. Advantageously, the sorbent prepared according to the present invention is not substantially dissolved when contacted with an acid. Therefore, the sorbent is not substantially dissolved during the leaching process.

[0132]

[0126] The source of manganese and the source of lithium may be milled together prior to heating, during heating at multiple steps and / or after heating. For example, the source of manganese and the source of lithium may be milled for about 5 minutes to about 10 hours.

[0133]

[0127] The lithium manganese oxide sorbent may be used to extract lithium from an aqueous solution containing lithium. The aqueous solution containing lithium may be obtained from a range of sources, e.g., geothermal brine, salar brine, sea water, formation water, produced water, concentrates from processing seawater, a waste stream from a lithium processing facility, a waste or process stream from a battery recycling plant, oil well brines, or other ground water. For example, geothermal brine may be used which has been processed by a silica extraction plant to remove or reduce silica.

[0134]

[0128] The lithium manganese sorbent will selectively adsorb lithium from an aqueous solution containing lithium. Other undesirable minerals, such as Ca, Fe, Mn, Mg as well as other components such as hydrocarbons may be adsorbed by the sorbent. These undesirable minerals and components are impurities that can be carried over with the sorbent. Nevertheless, the impurity levels can be controlled by the process of the lithium adsorption-desorption.

[0129] The following non-limiting examples are provided to illustrate the present invention and in no way limit the scope thereof.

[0135] EXAMPLES

[0136] Example 1: Sorbent synthesis and characterization

[0137] Experimental:

[0138]

[0130] The sorbent samples were prepared using different precursor materials with a fixed Li / Mn mol ratio of 0.75 with a total calcination time of lOh. The samples were ground in mortar and pestle until a fine powder mixture was obtained and then placed into a furnace in a closed crucible with the temperature tested from 500 to 700 °C.

[0139]

[0131] Lithium adsorption capacity (mg / g) was investigated using a synthetic solution buffered at pH 8 with 50 mg / L of lithium in DI water. The sorbent was dosed at 1 g / L and the tests were performed at ambient temperature. Lithium adsorption was analyzed using ICP-OES.

[0140]

[0132] X-Ray Diffraction (XRD) analysis was carried out to investigate the sorbent's crystal phase on the calcined samples. Laser diffraction analysis was performed to investigate the sorbent's particle size distribution.

[0141]

[0133] Thermogravimetric analysis (TGA) of sorbent samples was carried out to investigate the weight changes upon increasing the temperature. The heating rate was 10°C / min from ambient temperature to 900°C.

[0142]

[0134] A titration method was carried out as described by Freeman and Chapman (An Improved Oxalate Method for the Determination of Active Oxygen in Manganese Dioxide) to determine the sorbent chemical formula and manganese oxidation state. 180 mg of sorbent was digested in 25 mL of 0.10 M Na2C2O4 + 12.5 mL of 4.0 M H2SO4 at 80 °C until complete dissolution was reached. The digestions were then back-titrated using 0.010 M KMnO4 to a faint pink endpoint in order to determine the moles of oxalate which reacted, and therefore the moles of manganese in the sorbent that reacted with Na2C2C>4. Mass percentages of Mn and Li in each sorbent were determined by digesting 0.1 g of sorbent in 5 mL of 70% HNO3 + 40 mL DI water + 5 mL of 30% H2O2 at 60 °C for 1 h. Samples were then analyzed for Mn and Li concentrations using inductively coupled plasma optical emission spectrometry (ICP-OES); subsequently, the total moles of Mn in the sorbent used in the oxalate digestion was determined. The sorbent chemical formula was determined based on the mols of Mn obtained by the titration test and with the Li / Mn mol ratio obtained for the digested sample. The Mn average oxidation state (AOS) was then calculated using the sorbent formula in the form of LixMny04. Results:

[0143]

[0135] The sorbent samples were prepared using different precursor materials with a fixed Li / Mn mol ratio of 0.75 with a total calcination time of lOh. The samples were ground in mortar and pestle until a fine powder mixture was obtained and then placed into a furnace in a closed crucible to simulate the calcination with no active supply of oxygen. During the sorbent calcination trials the calcination temperature was tested from 500 to 700 °C. A summary of the test results is shown in Table 1 and Figures 1-4.

[0144] Table 1: Summary of the optimum test conditions for the samples calcined for a total of 10 hours, (capacity is shown as dry sorbent). Note: NM = not measured; mg / g = milligrams of lithium / grams of sorbent; Mn AOS = Manganese Average oxidation state.

[0145] *Li / Mn mol ratio obtained in the sorbent activation with acid.

[0146]

[0136] It was observed that calcination temperature of 500 °C resulted in improved sorbent capacity for most of the precursor mixtures tested, except the LiOH / Mn3O4 mixture where the optimum temperature was 600 °C. The examples are provided in Figures 1, 2, 3 and 4. Calcination at higher temperatures (e.g. 700 °C) may negatively affect the sorbent's capacity, possibly due to oxygen loss from the sorbent's structure.

[0147]

[0137] In Figure 1 and Table 1 the precursor mixture of LizCOs / MnsC (sample 1) is shown as an example of a carbonate-based precursor. The precursors were provided as a fine powder, and the grinding of the solids were facilitated as compared to the granular LiOH precursor. In this case, the sorbent's capacity was 22.97 mg / g calcined at 500 °C, and significantly higher than that of the sample calcined with a non-carbonate-based precursor. Consequently, a self-oxidizing mechanism is provided by the carbonate precursor mixture, as exemplified in equation 2, resulting in an increase in the oxidation state of the manganese in the resulting Lithium Manganese Oxide sorbent. This example supports that the air flow is not required during calcination using U2CO3 as the carbonate-based precursor, which facilitates the commercial scale calcination of the sorbent.

[0148]

[0138] In Figure 2 and Table 1 the precursor mixture of LiOH / Mn3O4 (sample 2) is shown as an example of an oxide and hydroxide-based precursor mixture. The LiOH was provided as granular particles, and the grinding of the precursor mixture was carried out until a homogeneous solid-solid mixture was obtained. The sorbent capacity was 9.41 mg / g in a total of 24 h upload time for the calcination at 600 °C. The calcination of the LiOH / MnsC mixture follows the mechanism as described in equation 1, therefore an active supply of air flow is a limiting step on the calcination of LiOH / MnsC precursor mixture. In this case, an active supply of air or O2 during calcination is required to manufacture a sorbent that can be used in multiple cycles in the DLE process.

[0149]

[0139] In Figure 3 and Table 1 the precursor mixture of LizCOs / MnCOs (sample 4) is shown using both carbonate-based precursors. The sorbent showed a maximum capacity of 9.97 mg / g for the calcination at 500 °C. The self-oxidizing precursor mixture can also be applied for the calcination of the LizCOs / MnCOs precursors; however the sorbent capacity was not as high as the sorbent calcined using LizCCh / MnsC .

[0150]

[0140] In Figure 4 and Table 1 the precursor mixture of LiOH / MnCOs (sample 5) is shown. The LiOH was provided as granular particles, and the grinding of the precursor mixture was carried out until a homogeneous solid-solid mixture was obtained. The maximum sorbent capacity was 9.91 mg / g for the calcination at 500 °C, which indicates that this precursor mixture was only partially self-oxidized in the calcination with no air flow.

[0151]

[0141] The optimum calcination conditions were found using the LizCCh / MnsC precursors calcined at 500 °C with no air flow, in a single calcination step for a total of lOh. The sorbent samples were tested comparing the calcination on a small scale - sample 1 (up to 100 grams) versus a larger scale - sample 3 (up to 50 kg) as a proof of concept that the calcination process works at scale. The large-scale calcination was tested with a total of 50 kg of the mixture of LizCCh / MnsC precursors placed into a batch kiln at 12 kg / cm2with no air or oxygen flow supplied. The sorbent obtained from the large-scale calcination has shown similar properties as the sorbent calcined at 0.1 kg scale in a laboratory furnace. These results are the supporting evidence that the calcination of the LizCCh / MnsC follows a self-oxidizing precursor mixture mechanism which facilitates the scaling up calcination of the Lithium Manganese Oxide sorbent for use in the DLE process.

[0152]

[0142] The sorbent properties were investigated using XRD, laser diffraction and TGA. The test methods are described in more detail in the experimental part.

[0153]

[0143] Particle size analysis of the calcined sorbent samples in a small (sample 1) and large scale (sample 3). The samples showed similar particle distribution with an average particle of 3.3 pm and 3.5 pm (represented as Dx50) for the small and large calcination scales respectively (Figure 5). This indicates that scaling the calcination batch effectively produced materials with very similar particle size distributions.

[0154]

[0144] X-Ray Diffraction (XRD) analysis was carried out to investigate the sorbent's crystal phases comparing samples 1 and 3 as shown in Figure 6, as examples of sorbent samples prepared using LizCCh / MnsC as the precursors. The samples tested have shown the main diffraction patterns attributed to a cubic spinel structure with the space group of Fd-3m, confirming the efficacy of calcining the sorbent at large scales.

[0155]

[0145] Thermogravimetric analysis (TGA) of sorbent samples was carried out to investigate the weight changes upon increasing the temperature. It has been reported in literature that the ion exchange sites can be identified in TGA analysis of acid activated sorbent samples (HMO form). As described by Seip the mass loss between 150 and 400°C can be assigned to structural water loss from condensation of lattice hydroxyl groups, which are formed during ion exchange with lithium, within the spinel structure of the sorbent. Therefore, the concentration of ion exchange sites can be indirectly determined from the weight loss in that region. The ion exchange sites can be calculated based on the sorbent chemical formula. In equation 5 an example is shown with a corresponding theoretical weight loss of about 9.4%, assuming fully oxidation in calcination where manganese on the sorbent is as Mn4+. The test results are shown in Figures 7-8.

[0156] Equation 5 5 H16Mn1604-> 8 MnO2+ 4 H2O

[0157]

[0146] The sorbent composition was further investigated by a titration method to determine the sorbent chemical formula and manganese average oxidation state (Mn AOS). In Table 1 is shown a summary of the calcination conditions and sorbent properties. Based on the TGA and Mn AOS results, the sorbent sample 1, calcined with the Li2CO3 / Mn3O4 precursors, resulted in Mn AOS of 3.3 and about 3.8% IX sites with the calculated chemical formula Lii,5Mn2O4. Whereas the sorbent sample 2, calcined with a non-carbonate-based precursor, have resulted in only about 2.4% IX sites.

[0158]

[0147] These results demonstrate that the calcination conditions can strongly affect sorbent's properties. Improved chemical stability and lithium equilibrium capacity can be achieved by using at least one carbonate-based precursor in the calcination of the lithium manganese oxide sorbent. The requirement for an active supply of air or O2 in calcination has been observed to be dependent on the precursor mixture, whereas a carbonate precursor mixture enables a self-oxidizing mechanism as described in equation 2.

[0159]

[0148] For commercial applications the calcination of the lithium manganese oxide sorbent was optimized to one single calcination step with no air flow and no milling steps for a batch of 50 kg, as shown in Table 1 (sample 3). The precursors to sample 3 were calcined with a total of 12 kg / cm2resulting in a thickness layer of about 3 cm, which allowed the solids to be evenly exposed to the heat during the calcination with a resulting capacity similar to the sample calcined at 0.1 kg scale. The results from the different calcination scales (from 0.1 to 50 kg) have shown that the milling process is not required with the optimum solids thickness layer of 3 cm or below to achieve even heat distribution from the surface to the bulk of the solids.

[0160]

[0149] The results presented in this example indicate that preferred conditions for the sorbent calcination include at least one carbonate-based precursor, a calcination temperature of 500 °C and a solids thickness layer in the calcination to achieve the complete conversion to the spinel lithium manganese oxide phase. It was also observed that the precursors mixture of LizCCh / MnsC provided the optimum sorbent properties for use in the DLE process with the sorbent showing the higher capacity to lithium ions. A similar selfoxidizing precursor mixture mechanism should be expected for at least one carbonate-based precursor. However, the manganese oxidation state in the MnsC is already at Mn2+ / Mn3+(often written as MnO-Mn2Os), whereas in the MnCOs it is at Mn2+, and therefore the complete oxidation to Mn4+is more difficult using MnCOs, especially in the large-scale calcination of the sorbent. Therefore, the use of MnsC is preferred over MnCOs for the calcination of the Lithium Manganese Oxide sorbent.

[0161] Example 2: Lithium adsorption capacity and chemical stability cycling test

[0162]

[0150] The lithium adsorption and desorption were performed in a multicycle test recycling the same sorbent, as shown in Figure 9. Lithium adsorption capacity (mg / g) was investigated using a natural lithium brine with lithium concentration of 100 mg / l for a total of 200 cycles using a 100 L tank. The sorbent sample 4 prepared in a large calcination batch was selected for this sorbent recycling trial. The tests were performed at 40 °C. The chemical stability of the sorbent was tested by measuring the amount of Mn2+in solution after each lithium desorption with acid for a total of 200 cycles. The concentration of manganese in solution was measured by ICP-OES and the sorbent's chemical stability in % was calculated based on the sorbent mass lost per cycle divided by the initial sorbent mass. The sorbent was regenerated after every lithium adsorption and desorption cycles.

[0163]

[0151] As shown in Figure 9, the sorbent performed well during the total of 200 cycles of lithium adsorption and desorption, with maintained capacity and chemical stability. On average, the sorbent's capacity was 9.95 mg / g for an average upload time of 20 minutes with an average of 0.06 wt% chemical damage to the sorbent during the trial. The multicycle trial result has shown that the lithium adsorption and desorption can be characterized as an ion exchange mechanism. The sorbent sample 3, which has been calcined in large calcination batch, has shown high chemical stability and no active supply of air or O2 was required. This sample demonstrates a sorbent with proven chemical stability as shown in the lithium extraction process for over 200 cycles with its re-use. Re-using the same sorbent for over 200 cycles can significantly reduce process costs for industrial application. Example 3: Sorbent calcination process using a batch kiln

[0164]

[0152] In Figure 10 is shown the schematic of a batch kiln calciner that has been used to manufacture a total of 50 kg of the precursors to the lithium manganese oxide sorbent placed in multiple trays. The sorbent calcination was carried out at a single calcination step, with a temperature ramp of 100 °C / h and holding time of lOh at 500 °C. The solids were placed into the trays at 12 kg / cm2. The kiln door was closed and there was no active supply of oxygen or air during the single calcination step. The cooling temperature ramp was 100 °C / h. The solids in each tray after the calcination was completed were mixed in a grinder and combined into one batch and bagged for storage in an airtight container.

[0165] Example 4: Sorbent calcination process using a conveyor kiln

[0166]

[0153] In Figure 11 an example is shown of a conveyor kiln calcination process where the precursors to the lithium manganese oxide sorbent are added continuously into trays in an automated conveyor at a rate of 12 kg / cm2. The conveyor kiln comprises a furnace with different heating zones, with the conveyor speed adjusted to achieve a total residence time of the solids of lOh at 500 °C, with no active supply of oxygen or air. The solids at the end of the conveyor are transferred into a grinder and bagged for storage in an airtight container.

[0167]

[0154] Where, in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

[0168]

[0155] Although the present disclosure has been described in terms of certain embodiments, other embodiments apparent to those of ordinary skill in the art also are within the scope of this disclosure. Thus, various changes and modifications may be made without departing from the spirit and scope of the disclosure. For instance, various components may be repositioned as desired. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present disclosure. Accordingly, the scope of the present disclosure is intended to be defined only by the claims that follow.

Claims

CLAIMS1. A process for preparing a lithium manganese oxide sorbent, the process comprising:(i) providing a precursor mixture of a source of manganese and a source of lithium; and(ii) heating the precursor mixture to produce a lithium manganese oxide sorbent, wherein the mixture is heated at about 300 to 1000°C for about 30 minutes to 48 hours; and wherein the source of lithium is lithium carbonate.

2. The process of claim 1, wherein at least about 40% of the manganese in the lithium manganese oxide sorbent is oxidized to an oxidation state of 4+, e.g., at least about 45%, about 50%, about 55%, about 60%, about 65% or about 70% of the manganese is oxidized to an oxidation state of 4+, e.g., at least about 95% of the manganese in the lithium manganese oxide sorbent is oxidized to an oxidation state of 4+, e.g., about 100% of the manganese in the lithium manganese oxide sorbent is oxidized to an oxidation state of 4+.

3. The process of claim 1, wherein the lithium manganese oxide sorbent comprises manganese with an average oxidation state greater than 3, e.g., greater than about 3.1, greater than about 3.2, greater than about 3.3, greater than about 3.4, or greater than about 3.5, greater than about 3.8, greater than about 3.9, e.g., the lithium manganese oxide sorbent comprises manganese with an average oxidation state of about 4.

4. The process of any one of claims 1 to 3, wherein the lithium manganese oxide increases in weight, after its initial loss of ignition, by 0.1 to 9% during the heating as a result of the increase in the oxidation state of the manganese provided by a self-oxidation of the precursor mixture.

5. The process of any one of claims 1 to 4, wherein the source of manganese is selected from the group consisting of a carbonate, a hydroxide, a nitrate, an oxide and a combination of any two or more thereof, e.g., wherein the source of manganese is selected from the group consisting of MnsC , MnzOs, MnCOs, MnO, Mn(NOs)2, MnOz, Mn(OH)2 and a combination of any two or more thereof; preferably, wherein, the source of manganese is manganese carbonate or manganese oxide.

6. The process of any one of claims 1 to 5, wherein the source of manganese is manganese oxide.

7. The process of any one of claims 1 to 6, wherein the source of lithium is heated with the source of manganese in a lithium : manganese mol ratio of about 0.30 to 1, about 0.40 to 0.95, about 0.50 to 0.90, about 0.60 to 0.85, or about 0.70 to 0.80, or about 0.75.

8. The process of any one of claims 1 to 7, wherein the source of manganese is a solid, a powder or a loose powder and / or the source of lithium is a solid, a powder or a loose powder.

9. The process of any one of claims 1 to 8, wherein the source of manganese and the source of lithium are milled together prior to heating.

10. The process of claim 9, wherein the milling step is performed with a ball mill, a ring mill, a bead mill, pulverizer, cement mixer, paddle blender, ribbon blender, and / or any other device able to mix the solid / solid precursor mixture and reduce aggregated particles and / or particle size.

11. The process of any one of claims 1 to 10, wherein the precursor mixture is heated in a furnace, e.g., in a static furnace or a conveyer furnace; optionally in a batch calcination process or a continuous calcination process; optionally in single calcination process or a multi step calcination process.

12. The process of claim 11, wherein the furnace comprises a continuous kiln with different heating zones or a batch kiln with different heating zones or a batch kiln with different heating temperature ramps or a conveyor furnace with different heating zones.

13. The process of any one of claims 1 to 12, wherein the precursor mixture is heated in a batch; optionally wherein the batch is at least about 30, 50, 60, 70, 80, 90 or 100 kg, e.g., wherein the batch is about 30 to 2000 kg, 50 to 1500 kg or about 100 to 1000 kg; optionally, wherein the process is carried out with multiple batches at the same time, e.g., multiple trays of the mixture in a single furnace.

14. The process of any one of claims 1 to 11, wherein the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 to 20 kg / m2, about 5 to 15 kg / m2or about 10 to 15 kg / m2.

15. The process of any one of claims 1 to 11, wherein the precursor mixture is heated in a continuous calcination process at a loading capacity of at least about 5 kg / m2, e.g., at least about 6 kg / m2, 7 kg / m2, 8 kg / m2, 9 kg / m2, 10 kg / m2, 11 kg / m2, 12 kg / m2, 13 kg / m2, 14 kg / m2, 15 kg / m2, 16 kg / m2, 17 kg / m2, 18 kg / m2, 19 kg / m2, 20 kg / m2, preferably at least about 10 kg / m2.

16. The process of any one of claims 11, 14 and 15 wherein the precursor mixture is heated in a continuous calcination process for a residence time of about 5 to 20 hours, e.g., about 5 to 19 hours, 5 to 18 hours, 6 to 17, 6 to 16, 7 to 15, 7 to 14 hours, 8 to 13 hours or 8 to 12 hours.

17. The process of any one of claims 1 to 11, wherein the precursor mixture is heated in a continuous calcination process at a loading capacity of about 5 to 20 kg / m2for a residence time of about 5 to 20 hours.

18. The process of any one of claims 13 to 17, wherein the precursor mixture has a thickness of about 1 to 10 cm during step (ii).

19. The process of any one of claims 1 to 18, wherein the precursor mixture is not substantially agitated during heating step (ii).20.. The process of any one of claims 1 to 19, wherein the precursor mixture is heated at about 400 to 800°C, e.g., about 450 to 700°C, about 450 to 600°C or about 450 to 550°C.

21. The process of any one of claims 1 to 15, wherein the precursor mixture is heated for about 2 to 24 hours, e.g., about 4 to 12 hours.

22. The process of any one of claims 1 to 21, wherein step (ii) is performed in a closed vessel.

23. The process of any one of claims 1 to 22, wherein the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least 10 mg / g once the lithium in the lithium manganese oxide has been leached out.

24. The process of any one of claims 1 to 23, wherein the lithium manganese oxide sorbent is a powder having an average particle size of less than about 100 microns.

25. The process of any one of claims 1 to 24, wherein the source of lithium and the source of manganese are milled separately before being mixed at different mol ratios.

26. The process of any one of claims 1 to 25, wherein the process further comprises leaching lithium out of the lithium manganese oxide sorbent, e.g., leaching lithium out of the lithium manganese oxide sorbent with an acid, e.g, a mineral acid, such as HCI and / or H2SO4, or weaker acids such as phosphoric or other weak acids.

27. The process of claim 26, wherein the sorbent is not substantially dissolved in the process of leaching lithium out of the lithium manganese oxide sorbent.

28. A lithium manganese oxide sorbent made by the process of any one of claims 1 to 27.

29. A lithium manganese oxide sorbent having a lithium equilibrium capacity of at least about 10 mg / g. In some embodiments, the lithium manganese oxide sorbent has a lithium equilibrium capacity of at least about 20 mg / g, e.g., about 20 to 35 mg / g.

30. The lithium manganese oxide sorbent of claim 28 or 29, wherein the lithium manganese oxide sorbent comprises a spinel phase.

31. The lithium manganese oxide sorbent of any one of claims 28 to 30, wherein the sorbent is not substantially dissolved when leaching lithium out of the lithium manganese oxide sorbent, e.g., leaching lithium out of the lithium manganese oxide sorbent with an acid, e.g, a mineral acid, such as HCI and / or H2SO4, or weaker acids such as phosphoric or other weak acids.

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