Process for pre-treatment of water for direct lithium extraction

Abstract

A process for pre-treatment of a brine (containing desirable and undesirable metal ions in solution) for direct lithium extraction. The process comprises subjecting the brine to a selective biological / microbial induced carbonate precipitation process with an organic substrate comprising urea, ureolytic microorganisms comprising Sporosarcina pasteurii, and / or urease enzymes, to precipitate undesirable metals as metal carbonates. The precipitation of these undesirable metals from the brine improves the efficiency of downstream direct lithium extraction.

Description

PROCESS FOR PRE-TREATMENT OF WATER FOR DIRECT LITHIUM EXTRACTION

[0001] The present disclosure relates to processes for the pre-treatment of water, including but not limited to brine from seawater, other natural sources and industrial oil sand operations, involving the use of a biological metal precipitation process to facilitate direct lithium extraction.

[0002] The global transition away from fossil fuels is creating an enormous demand for high-performance batteries and electric vehicles. Lithium (Li) is highly conductive due to its low electron affinity, making it an excellent material for high-performance batteries. Lithium batteries are rechargeable, store energy efficiently, and are lightweight compared to other types of batteries. Lithium is recognized as a critical mineral because of its high demand and a lack of substitute materials that can perform similarly. It has been reported that almost 60% of current lithium mined is used for battery related applications and that figure could reach 90% by 2030. Demand for Li (and Li batteries) is expected to keep increasing in the coming years, especially until Li battery recycling technology improves.

[0003] Lithium is either mined directly via hard-rock mining, typically from pegmatite deposits with Li-bearing minerals (e.g., spodumene, lepidolite), or extracted from Li-bearing fluids like seawater, and natural and industrial brines. Natural brines include continental and geothermal brines and industrial brines include byproducts from desalination processes and extraction of oil and natural gas. Recovery of Li from oil sands process-affected water (OSPW) in North America is gaining interest. Seawater and brines are multi-metal, chemically complex matrices which makes selective Li extraction and purification challenging. Conventional direct lithium extraction (“DLE”) methods result in low Li yields (~30-40%) and high process costs due to the loss of lithium in the form of an insoluble component. Techniques currently used for DLE from brines include desalination, solar evaporation, electrochemistry, adsorption, and ion exchange. For any of these DLE methods, a pre-treatment step to remove interfering metal cations may be employed to improve method selectivity and Li extraction efficiency. Adsorption and electrochemical methods have been applied as pre-DLE treatments to remove interfering metal cations (e.g., Ca2+, Fe2+and Mg2+), but resulted in low efficiency / removal rates. Oil field brines also contain high levels of barium and strontium that are of concern to the environment. Traditional methods of barium and strontium removal include reverse osmosis and electrodialysis which are expensive and have slower process rates.

[0004] Disclosed herein is a process for pre-treatment of treatment water (also sometimes referred to herein as “brine”) consisting of the use of biological precipitation to produce treated water that is suitable for direct lithium extraction and that meets downstream discharge regulations. The process significantly reduces metal interferences that lead to low lithium extraction limits. The process may also recover metals of interest as metal carbonates and / or remove undesirable / environmentally toxic metals.

[0005] The present disclosure includes a process for treating treatment water or brine to remove metals (that would otherwise interfere in the downstream direct lithium extraction process) in the form of metal carbonates, by introducing bacteria that induce carbonate formation from urea.

[0006] In one aspect of the present invention, the treatment water is an aqueous composition consisting of dissolved metal and / or chlorides, and the pre-treatment process involves subjecting the aqueous composition to a biological precipitation process to produce a treated aqueous composition having no, or a reduced amount of, dissolved interfering metals.

[0007] In one aspect, the treatment water is natural seawater. In another aspect, the treatment water is concentrated or diluted brine. In a further aspect, the treatment water is processed water from oil and gas operations. In another aspect, the treatment water is drainage, tailings, or acid rock drainage, or leachate from hard rock or spodumene lithium extraction.

[0008] In one aspect, the biological process further results in precipitation of dissolved metals as metal carbonates by microbial induction, enzymatic induction or combinations thereof.

[0009] In an embodiment, the microbial induced carbonate precipitation process consists of ureolytic microorganisms and organic substrate in a nucleation vessel, mixing tank, clarifier or thickener (“vessel”), wherein the ureolytic microorganism is a bacteria and / or fungi that will be introduced into the vessel, and the organic substrate is urea and / or recycled organic matter containing urea, which will produce carbonates through urea hydrolysis and precipitate the dissolved metals out of the brine, leaving ions of dissolved lithium in solution.

[0010] In some aspects, the ureolytic microorganisms comprises bacteria such asSporosarcina pasteurii, Bacillus firmus, Bacillus subtilis, Helicobacter pylori, Acinetobacter sp, Pseudomonas, Bacillus licheniformis, Klebsiella aerogenes, Mycobacterium tuberculosis, Canavalia ensiformisor combinations thereof; and / or sulfate reducing bacteria comprisingDesulfovibrio; and / or ureolytic fungi.

[0011] In some aspects, the microorganism is able to induce carbonate precipitation through non-ureolytic means, such as denitrification, photosynthesis and CO2hydration, andincludes Alcaligenes faecalis, Pseudomonas denitrificans, Denitro bacillusra, Thiobacillus sp., Spirillum sp., Micrococcus sp., Acinetobacter johnsonii, Cupriavidus sp., Halmonas alkaliphilia, Synechococcus sp. PCC 7942, Synechococcus sp. PCC 7002, Synechococcus elongatus, Geloeocapsa sp. F-6gl, Anabaena variabilis, Anabaena PCC 7120, Synechocystis sp. ATCC 27178, andSynechocystis sp. PCC 6803 and Sulfurihydrogenibium azorense, Sulfurihydrogenibium yellowstonense, Thermovibrio ammonificans, andBacillus halodurans.

[0012] In some aspects, the treatment water is an aqueous composition comprising ions of dissolved metal and wherein at least one dissolved metal is precipitated as metal carbonate in a mixing tank, a clarifier, thickener, nucleation tank or combinations thereof. In another aspect, the metal precipitated in the nucleation vessel comprises at least one of: calcium carbonate, magnesium carbonate, barium carbonate, strontium carbonate, zinc carbonate, iron carbonate, manganese carbonate or combinations thereof. In further aspects, the process may be utilized to sequester carbon dioxide from the environment by precipitating dissolved metals from the brine in the form of carbonates or complexes thereof through urea hydrolysis. In a further aspect, dissolved metals that would otherwise interfere with direct lithium extraction processes (including but not limited to calcium, magnesium and iron) are precipitated partially as metal carbonates or complexes thereof.

[0013] In one aspect, the process comprises removing at least one dissolved interfering metal (“metal interferences”) as metal carbonate and / or as a metal or a complex thereof.

[0014] In one aspect, the process further comprises treating the treatment water with a biological induced precipitation process at pH between 7 - 9. In a further aspect, the process may include neutralizing the treatment water with microbially induced metal carbonates, if the treatment water is at a pH lower than 7.

[0015] In yet another aspect of the present invention, also disclosed herein is a process for extracting lithium from a brine, comprising any of the above disclosed processes for pre-treatment of treatment water, followed by applying any conventional process for DLE.

[0016] Other features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the disclosure, are given by way of illustration only and the scope of the claims should not be limited by these embodiments, but should rather be given the broadest interpretation consistent with the description as a whole.Brief Description of the Drawings

[0017] is a schematic diagram of a process for pre-treatment of brine / treatment water for direct lithium extraction according to one aspect of the present disclosure.

[0018] is a graph showing metal carbonate precipitation (mM) as a function of time (hours) in a mixing tank at 30°C while maintaining lithium in solution according to an aspect of the present disclosure.

[0019] is a graph showing metal carbonate precipitation (mM) as a function of time (hours) in a mixing tank at 50°C with low lithium removal rates according to an aspect of the present disclosure.

[0020] Unless otherwise indicated, the definitions and embodiments described in this and other sections are intended to be applicable to all embodiments and aspects of the disclosure herein described for which they would be understood to be suitable by a person skilled in the art.

[0021] The term “and / or” as used herein means that the listed items are present, or used, individually or in combination. In effect, this term means that “at least one of” or “one or more” of the listed items is present or used.

[0022] As used in this disclosure, the singular forms “a”, “an” and “the” include plural references unless the content clearly dictates otherwise.

[0023] As used herein, the words “comprising” (and any form thereof, such as “comprise” and “comprises”), “having” (and any form thereof, such as “have” and “has”), “including” (and any form thereof, such as “include” and “includes”) or “containing” (and any form thereof, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unrecited elements or process / method steps. As used herein, the word “consisting” and its derivatives are intended to be close-ended terms that specify the presence of the stated features, elements, components, groups, integers and / or steps, and also exclude the presence of other unstated features, elements, components, groups, integers and / or steps. The term “consisting essentially of”, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and / or steps as well as those that do not materially affect the basic and novel characteristic(s) of these features, elements, components, groups, integers and / or steps.

[0024] The term “suitable” as used herein means that the selection of the particular conditions would depend on the specific manipulation or operation to be performed, but the selection would be well within the skill of a person trained in the art. All processes described herein are to be conducted under conditions sufficient to provide the desired product.

[0025] Processes and Uses. Lithium is a crucial component in batteries for electric vehicles and other chemical applications. Lithium is found in water, including synthetic and natural brines, spent water from oil and gas operations and other recycled water streams. Lithium is conventionally extracted from such water using an ion exchange (direct lithium extraction) process wherein the lithium is adsorbed onto the ion exchange membrane. The absorbed lithium is eluted out from the membrane by washing with acid solution. The membrane adsorbing lithium comprises beads that might uptake other metals as well. Efficient lithium uptake depends on suitable pH conditions and concentrated water without metal interferences. Inefficient lithium uptake may also result due to other metals precipitating onto the membrane and clogging the membrane.

[0026] While the present invention finds application in the context of a process for pre-treatment of a brine in order to facilitate a DLE process (and is illustrated and described herein as such), it should be understood that the present invention is not limited to such, and other applications, embodiments and variations will be apparent to a person skilled in the art.

[0027] Direct lithium extraction technology can be used to remove desirable metals like lithium from treatment water or brine. The presence of undesirable or interfering metals might reduce the efficiency of the direct lithium extraction process. The removal of such undesirable metals, environmentally toxic and / or unsafe metals from the treatment water can be very challenging and time consuming. Disclosed herein are processes for separating such undesirable metals. Undesirable metals may be precipitated out of the treatment water at neutral pH.

[0028] Treatment Water. As used in the present disclosure, treatment water may refer to a natural brine, a salt flat, a salar, seawater, concentrated seawater, concentrated brine, spent water from oil sand operations, water from oil and gas operations, liquid from solar evaporation, liquid from chemical evaporation, a geothermal brine, processed water containing lithium, recycled water, water containing one or more dissolved salts, a synthetic brine, rock drainage, acid rock drainage, tailings, leachate from hard rock mining processes or combinations thereof.

[0029] In one aspect, the treatment water in the reaction vessel is at a temperature of -10 °C to 200 °C. In some aspects, the treatment water in the reaction vessel is at a temperature of -10 °C to 20 °C, 20 °C to 50 °C, 50 °C to 100 °C, 100 °C to 200 °C. In yet other aspects, the treatment water (or the treatment water in the reaction vessel) is heated or cooled down to a suitable processing temperature to facilitate removal of certain metals from the treatment water as a precipitate and / or to create suitable conditions for the ureolytic microorganisms.

[0030] In some aspects, the pH of the treatment water in the reaction vessel is adjusted to less than 0, 0 to 2, 2 to 4, 4 to 6, 6 to 7, 7 to 9, 9-10 or 10-14. In some aspects, the pH of the treatment water in the reaction vessel is adjusted to 1 to 3, 3 to 6, 7 to 9 or 9-12. In another aspect, the pH of the treatment water in the reaction vessel is adjusted to facilitate one or both of precipitation or dissolution of certain dissolved metals.

[0031] In an embodiment, the treatment water contains lithium at a concentration between 0 and 5000 mg / L. In one embodiment, the treatment water contains calcium at a concentration between 0 and 150,000 mg / L. In one embodiment, the treatment water contains magnesium at a concentration between 0 and 200,000 mg / L. In one embodiment, the treatment water contains barium at a concentration between 0 and 10,000 mg / L. In one embodiment, the treatment water contains iron at a concentration between 0 and 20,000 mg / L. In one embodiment, the treatment water contains copper at concentrations between 0 and 1000 mg / L. In one embodiment, the treatment water contains zinc at concentrations between 0 and 1000 mg / L. In one embodiment, the treatment water contains lead at concentrations between 0 and 2000 mg / L.

[0032] In an embodiment, the treatment water is processed through precipitation to remove undesirable metals and retain desirable metals such as lithium. In one embodiment, the precipitated lithium concentrations from treatment water is at a concentration between 0 to 500 mg / L. In one embodiment, the precipitated lithium concentration contains less than 1 mg / L, between 1 to 5 mg / L, between 5 to 10 mg / L, between 10 to 20 mg / L, between 20 to 50 mg / L, between 50 to 70 mg / L, between 70 to 100 mg / L, between 100 mg / L to 500 mg / L or greater than 500 mg / L.

[0033] In an embodiment, one or more metals are precipitated from the treatment water to form at least one metal carbonate precipitate. In an embodiment, the metal carbonate precipitate may be in the form of a slurry, a filter, a cake, a dry filtered cake, a dry powder, and / or a dilute precipitate containing solution. In one embodiment, the precipitates include metal sulfates, metal carbonates, metal hydroxides, sulfides, or combinations thereof.

[0034] In one embodiment, the precipitates are environmentally toxic, unsafe and / or radioactive. In one embodiment the precipitates might be desirable and recycled back into the treatment process, as a slurry. In one embodiment, the precipitate might be desirable and redissolved in acids to use in the process.

[0035] Process for Removing Undesirable and / or Environmentally Toxic Metals to Facilitate Direct Lithium Extraction Process. Processes that are used for conventional direct lithium extraction can be used to recover one or more desirable metals from treatment water. In one embodiment, desirable metals may include Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, Po, and / or other metals. In one embodiment, the treatment water or brine contains one or more undesirable metals. In one embodiment, undesirable metals and / or toxic metals may include Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, Po, and / or other metals. In one embodiment, one or more metals are undesirable for a certain process but are desirable for a different process. In one embodiment, one or more metals are environmentally toxic for a certain process but are desirable for a different process.

[0036] In a preferred embodiment, the desirable metal is lithium and the undesirable metal is one or more of calcium, magnesium, barium, strontium, manganese, iron and zinc.

[0037] In one embodiment, direct lithium extraction processes involve ion exchange process, solvent extraction, adsorption, membrane technologies and combinations thereof. In one embodiment, undesirable metals include iron, manganese, calcium and magnesium in the ion exchange process.

[0038] In one embodiment, undesirable metals are removed from the treatment water using a selective biologically induced carbonate precipitation process wherein desirable metals are retained in the treated water. In another embodiment, the metal carbonate precipitation produced from the biological precipitation process can be used to neutralize incoming water that may be present at an acidic pH. In another embodiment, the metal carbonate precipitation produced from the biological precipitation process can be used to neutralize spent water downstream of the direct lithium extraction process that may be present at an acidic pH.

[0039] The microbial induced carbonate precipitation process comprises metal precipitation as metal carbonate that is microbially induced, enzymatically induced or combinations thereof. (It is presently contemplated that microbial induction is more preferred due to economical considerations). The microorganisms for metal carbonate precipitation are any suitable microorganisms that perform urea hydrolysis (or combinations thereof), including native and engineered strains thereof. The mechanism for metal carbonate precipitation is induced through an increase in alkalinity due to ammonium formation, resulting in carbonate anions. The microorganisms undergo an ureolysis that promotes the formation of metal carbonate as a result of urease enzyme that is present in the ureolytic microorganism (e.g bacteria, fungi, etc.). In an embodiment, the metal precipitation directly occurs due to urease enzymes in cell free systems acting on the organic substrate to form carbonate anions. In one embodiment, biological precipitation of metal carbonates is understood to comprise the steps described below.

[0040] The major metabolic pathway entails urea hydrolysis by urease enzymes present intracellularly in ureolytic bacteria or present as purified enzymes in cell free systems. The major metabolic pathways entail urea hydrolysis and metal carbonate precipitation driven by urease and carbonic anhydrase. One mole of urea is hydrolysed by urease to produce one mole of ammonia and carbamate.

[0041] CO(NH2)2+ H2O → NH2COOH + NH3

[0042] Carbamate is spontaneously hydrolysed to produce one mole each of ammonia and carbonic acid.

[0043] NH2COOH + H2O → NH3+ H2CO3

[0044] Carbonic acid is converted to bicarbonate and two moles of ammonium and hydroxide are formed due to ammonia hydrolysis.

[0045] H2CO3↔ HCO3−+ H+

[0046] 2NH3+ 2H2O → 2NH4++ 2OH-

[0047] Correspondingly, pH in the cells increases leading to the conversion of HCO3-to CO32-and induces metal carbonate precipitation in the presence of dissolved metals present in water.

[0048] HCO3−+ H++ 2NH4++ 2OH-→ CO32−+ 2NH4++ 2H2O

[0049] Cells + metal cations + CO32−→ Cells + metal carbonates

[0050] Suitable microorganisms for inducing metal precipitation express active variants of urease and carbonic anhydrase. In an embodiment, active and purified enzymes of urease and carbonic anhydrase are utilized for metal carbonate precipitation. In one embodiment, suitable microorganisms for metal carbonate precipitation with active urease and carbonic anhydrase compriseSporosarcina pasteurii, Bacillus firmus, Bacillus subtilis, Helicobacter pylori, Acinetobacter sp, Pseudomonas, Bacillus licheniformis, Klebsiella aerogenes, Mycobacterium tuberculosis, Canavalia ensiformisor combinations thereof; and / or sulfate reducing bacteria comprisingDesulfovibrio; and / or ureolytic fungi or combinations thereof. In another embodiment, suitable microorganisms for metal carbonate precipitation using non-ureolytic pathways compriseAlcaligenes faecalis, Pseudomonas denitrificans, Denitro bacillusra, Thiobacillus sp., Spirillum sp., Micrococcus sp., Acinetobacter johnsonii, Cupriavidus sp., Halmonas alkaliphilia, Synechococcus sp. PCC 7942, Synechococcus sp. PCC 7002, Synechococcus elongatus, Geloeocapsa sp. F-6gl, Anabaena variabilis, Anabaena PCC 7120, Synechocystis sp. ATCC 27178, andSynechocystis sp. PCC 6803andSulfurihydrogenibium azorense, Sulfurihydrogenibium yellowstonense, Thermovibrio ammonificans, Bacillus haloduransor combinations thereof.

[0051] In one embodiment, the biological precipitation process comprises allowing treatment water with undesirable metals into a nucleation vessel. Further, urea or organic substrate including urea or combinations thereof is introduced into the vessel as organic substrate. In another embodiment, the microorganism and / or ureolytic enzymes for metal carbonate precipitation is cultured in a growth reactor and then added to the treatment water containing dissolved metals at suitable cell density for the biological metal precipitation process. In another embodiment, the process comprises carbon dioxide sequestration from the environment for carbonate production and further biological metal carbonate precipitation.

[0052] In an embodiment, the biological precipitation process is adjusted to a suitable temperature for microbial activity in the nucleation tank to 30-60°C.

[0053] In an embodiment, treatment water containing undesirable metal interferences in the direct lithium extraction process are adjusted to a pH suitable for metal precipitation in a mixing tank / reaction vessel. In an embodiment, the suitable pH for biological induced metal precipitation is 7-9. In an embodiment, the treatment water containing undesirable metals is adjusted to pH 7-9 by recycling biologically produced metal carbonates. The treatment water at an adjusted pH 7-9 with undesirable metals is precipitated out of water through microbial activity. The metal carbonate precipitation comprises of at least one or more desirable metals such as Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, Po, and / or other metals precipitated as metal carbonates.

[0054] In an embodiment, the process further comprises retaining one or more desirable metals as dissolved ions in solution following biological precipitation. The one or more desirable metal ions comprise Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, Po, and / or other metals. More specifically, it is contemplated that, besides being used as a pre-treatment process for lithium, the process may also be used / adapted as a pre-treatment process for other metals, such as gold, platinum-group metals and / or silver. In an embodiment, partial precipitation of one or more metals as metal carbonates might occur comprising Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, Po, and / or other metals.

[0055] In an embodiment, environmentally toxic and / or undesirable metals should be removed from water to be fit for discharge. Environmentally allowed metal concentrations are outlined by Maximum Authorized Concentrations of Prescribed Deleterious substances: https: / laws-lois.justice.gc.ca / eng / regulations / sor-2002-222 / page-8.html. In an embodiment, water containing environmentally unsafe and / or toxic metals downstream of direct lithium extraction process is introduced into a nucleation vessel and subjected to one or more precipitation cycles resulting in precipitation of toxic metals comprising but not limited to, one or more of: Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, and Po.

[0056] In a further embodiment, the water following precipitation of undesirable and toxic metals and retainment of desirable metals is subjected to one or more processes comprising concentration, upgrading, extraction, reverse osmosis, ion exchange and solvent extraction for direct lithium extraction. In an embodiment, lithium extracted from water is in the form of lithium carbonate, lithium hydroxide, lithium chloride or complexes thereof.

[0057] The following are non-limiting examples of the present disclosure.Examples

[0058] Example 1: Microbial induced carbonate precipitation to remove undesirable metals (including environmentally toxic metals or metals that act as metal interferences in direct lithium extraction process) while retaining lithium as dissolved metal in the treated water.

[0059] As illustrated in, 50 mL of treatment water (102) (containing metal interferences such as magnesium and calcium and toxic metals such as barium and strontium) was introduced into a nucleation vessel.Sporosarcina pasteurii, cultured overnight at 30°C in a growth bioreactor served as ureolytic bacteria containing active urease and carbonic anhydrase in this study. The ureolytic bacteria (104) was added to a suitable cell density to the nucleation vessel containing water, along with an organic substrate comprising urea (104). The setup was incubated at pH 7.5, 30°C, and 200 rpm in an incubator overnight to observe metal carbonate precipitation. Following overnight incubation, metal carbonate precipitation was observed in the underflow (106) and desirable metals were retained in the overflow (108). Dissolved metal concentration in the supernatant was measured via inductively-coupled plasma mass spectrometry (ICP-MS).

[0060] Complete substrate (urea) utilization was measured through urea colorimetric assay. ICP-MS results show high retention of desirable metals comprising lithium (13.3% mean loss) and near complete removal of toxic metals such as barium and strontium. The process also resulted in ~100% and 85% removal of metal interferences such as calcium and magnesium respectively (see).

[0061] Treatment water containing the same concentrations of metals was also studied at a higher temperature of 50°C. ICP-MS results showed consistent undesirable and toxic metal removal rates and high retainment of desirable metals comprising lithium to facilitate an efficient lithium extraction process (see).

[0062] While the disclosure has been described with reference to what are presently considered to be the preferred examples, it is to be understood that the disclosure is not limited to the disclosed examples. To the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0063] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. Where a term in the present application is found to be defined differently in a document incorporated herein by reference, the definition provided herein is to serve as the definition for the term.

Claims

A process for pre-treatment of a brine in the form of an aqueous composition, the aqueous composition containing in solution ions of one or more undesirable metals and ions of one or more desirable metals, the process comprising:subjecting the aqueous composition to a selective carbonate precipitation process comprising a microbial induced carbonate precipitation step and / or an enzymatically induced carbonate precipitation step to produce:a precipitate of the one or more of the undesirable metals, in the form of a metal carbonate or a complex thereof; anda treated water comprising the ions of the one or more desirable metals in solution;andseparating the precipitate of the one or more undesirable metals from the treated water.The process of claim 1, wherein the desirable metal is lithium.The process of claims 1 or 2, wherein the undesirable metal is an alkali metal; an alkaline earth metal; a transition metal; arsenic; barium; strontium; cesium; copper; lead; nickel; zinc and / or combinations thereof.The process of claim 2, wherein said process is used to facilitate direct lithium extraction (“DLE”), and wherein subsequent to the step of separating the precipitate of the one or more undesirable metals from the treated water, the treated water is subjected to a conventional DLE process to extract lithium from the treated water.The process of claim 2, wherein the selective carbonate precipitation process comprises:adding urea or an organic substrate containing urea; andadding a ureolytic microorganism and / or an urease enzyme.The process of claim 5, wherein the ureolytic microorganism comprises one or more of:Sporosarcina pasteurii; Bacillus firmus; Bacillus subtilis; Helicobacter pylori; Acinetobacter sp; Pseudomonas; Bacillus licheniformis; Klebsiella aerogenes; Mycobacterium tuberculosis; Canavalia ensiformis; sulfate reducing bacteria comprisingDesulfovibrio; and ureolytic fungi.The process of claim 5. wherein the step of adding a ureolytic microorganism, additionally comprises adding growth media to sustain the ureolytic microorganism.The process of claim 2, wherein the brine is seawater; a salar comprising lithium, sodium, potassium or combinations thereof; spent water from oil and gas operations; mine tailings; rock drainage; acid rock drainage; or lithium-containing hard rock leachates.The process of claim 2, wherein the selective carbonate precipitation process additionally comprises adding a base or an acid to the aqueous composition to adjust a pH of the aqueous composition.The process of claim 2, wherein the selective carbonate precipitation process additionally comprises adding MgCO3and / or H2SO4to the aqueous composition.The process of claim 2, wherein the aqueous composition has a pH of between 7-9.The process of claim 2, wherein the precipitate of the one or more undesirable metals is recycled to the selective precipitation process in order to adjust the aqueous solution to a pH of between 7-9.The process of claim 2, wherein the selective carbonate precipitation process is carried out in one or more of: a mixing tank; a thickener; a clarifier; a centrifuge; a hydrocyclone; a nucleation tank and a reactor.The process of claim 2, wherein the step of separating the precipitate of the one or more undesirable metals from the treated water involves filtration, gravity separation, centrifugal separation and / or combinations thereof.The process of claim 2, wherein the process for pre-treatment is a batch process, a semi-batch process, or a continuous process.The process of claim 2, wherein the one or more undesirable metals is environmentally toxic and / or unsafe, and includes barium, strontium and / or arsenic.A process for sequestration of carbon dioxide comprising subjecting a brine in the form of an aqueous composition, the aqueous composition containing in solution ions of one or more undesirable metals, the process comprising:subjecting the aqueous composition to a carbonate precipitation process comprising a microbial induced carbonate precipitation step and / or an enzymatically induced carbonate precipitation step to produce a precipitate of the one or more of the undesirable metals, in the form of a metal carbonate or a complex thereof,wherein the carbonate precipitation process comprises:adding urea or an organic substrate containing urea; andadding a ureolytic microorganism and / or an urease enzyme.

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