Method of producing potassium sulfate salts and carbonic acid salts from sodium sulfate byproduct

Abstract

The present invention provides carbonation methods for treating industrial byproduct streams comprising sodium sulfate with one or more carbonation reagents, including but not limited to (i) potassium bicarbonate and / or potassium carbonate; or (ii) carbon dioxide (CO2) and a potassium salt, thereby producing (i) a solid phase comprising one or more potassium sulfate salts and (ii) a liquid phase comprising carbonic acid salts in solution. The one or more potassium sulfate salts comprise potassium sulfate (K2SO4), glaserite, or other sodium potassium sulfate salts. The carbonic acid salts comprise sodium carbonate (Na2CO3) and / or sodium bicarbonate (NaHCO3). The present invention also provides processes for isolating the aforementioned salts from industrial byproduct streams. The present invention also provides cyclical processes for recovering and recycling reagents for producing the aforementioned salts from the industrial byproduct streams and from product streams containing the aforementioned salts.

Description

ATTY DOCKET NO. 1149704.094013METHOD OF PRODUCING POTASSIUM SULFATE SALTS AND CARBONIC ACID SALTS FROM SODIUM SULFATE BYPRODUCTRelated Applications

[0001] The present invention relates to and claims benefit of priority to U.S. Provisional Application Number 63 / 725,108 filed on November 26, 2024, and Finnish Application Number FI 20255154, filed on February 20, 2025, the contents of all of which are incorporated by reference in their entireties herein.

[0002] All patents, patent applications and publications cited herein are hereby incorporated by reference in their entirety. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described and claimed herein.

[0003] This patent disclosure contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves any and all copyright rights.FIELD OF THE INVENTION

[0004] The present invention relates to carbonation methods for treating industrial byproduct streams comprising sodium sulfate, thereby producing (i) potassium sulfate and salts thereof and (ii) carbonic acid salts from. The invention also relates to processes for isolating the aforementioned salts from industrial byproduct streams. The invention also relates to cyclical processes for recovering and recycling materials from the industrial byproduct streams and from product streams containing the aforementioned salts.BACKGROUND OF THE INVENTION

[0005] Sodium sulfate is a substantial byproduct derived from a variety of industrial sectors including pulp and paper, mining, textiles, and cathode active material production industries. For example, electric vehicle (EV) battery gigafactories generate substantial quantities of byproduct containing sodium sulfate (Na2SO4). To put this into perspective, circa 4.5 million tons of Na2SO4 is generated annually in the global precursor cathode active material (pCAM) production of 8 million tons.

[0006] Na2SO4 is not toxic, but high sulfate concentrations cause water salinity, harm the ecosy stem, and can be very' dangerous to ruminants like moose and cattle. As the battery plants ramp up production, byproduct streams and their content are becoming critical considerations for obtaining the legislative and social license to operate.

[0007] The main commercial Na2SO4 treatment technologies are based on Na2SO4 cry stallization or precipitation of sulfate as sparingly soluble compounds, e.g., as gypsum andATTY DOCKET NO. 1149704.094013 etringite. Crystallization is simple but its operating costs are rather high due to its high energy consumption. Precipitation requires huge amount of chemicals and handling of low- value end products. Na2SO4 can be also upcycled in caustic and acid by bipolar electrodialysis (BPED), but the required purification of the Na2SO4 feed and concentration of caustic and acid to commercial market concentration make the technology costly and complex.

[0008] Therefore, based on the foregoing, a cost-effective industrial byproduct conversion and recycling process remains a technical challenge.

[0009] The present invention addresses this technical challenge by providing carbonation methods for treating sodium sulfate byproduct with one or more carbonation reagents to produce potassium sulfate salts and carbonic acid salts.SUMMARY OF THE INVENTION

[0010] The present invention provides carbonation methods for treating industrial byproduct streams comprising sodium sulfate with one or more carbonation reagents, including but not limited to (i) potassium bicarbonate and / or potassium carbonate; or (ii) carbon dioxide (CO2) and a potassium salt, thereby producing (i) one or more potassium sulfate salts and (ii) carbonic acid salts. More particularly, the invention relates to processes for isolating the aforementioned salts from industrial byproduct streams. The invention also provides cyclical processes for recovering and recycling materials from product streams containing the aforementioned salts.

[0011] In one aspect, the present invention provides a method of producing (i) one or more potassium sulfate salts and (ii) one or more carbonic acid salts from a sodium sulfate byproduct stream, the method comprising at least steps (a)-(c) as set forth below:

[0012] (a) contacting the sodium sulfate byproduct stream with at least one carbonation reagent, thereby producing a solid stream comprising said potassium sulfate salts and a liquid stream comprising said carbonic acid salts, wherein the carbonation reagent comprises (i) potassium bicarbonate and / or potassium carbonate; or (ii) carbon dioxide (CO2) and a potassium salt; (b) isolating the solid stream comprising potassium sulfate salts; and (c) isolating the liquid stream comprising said carbonic acid salts.

[0013] In certain embodiments of the method:

[0014] (i) step (b) comprises isolating the solid stream from the liquid stream by solid-liquid separation, optionally comprising setling, centrifugation, and / or filtration to form an isolated solid: (ii) the solid stream comprises said potassium sulfate salts and optionally a residual amount of said carbonic acid salts: (iii) the liquid stream comprises said carbonic acid salts and optionally a residual amount of said potassium sulfate salts; (iv) said potassium sulfate salts comprise potassium sulfate (K2SO4); glaserite (K3Na(SO4)2): a mixture of potassium sulfate and glaserite; one or more additional potassium sodium sulfate salts of the form KnNam(SO4)2, wherein n and m are between 1 and 3; one or more additional potassiumATTY DOCKET NO. 1149704.094013 sodium sulfate salts of the form KxNay(SO4)4, wherein x and y are between 1 and 7; or any combination of the foregoing; (v) said carbonic acid salts comprise sodium carbonate, sodium bicarbonate, or a mixture thereof; (vi) when step (a) is performed at a pH ranging from 7-9, the primary carbonic acid salt comprises sodium bicarbonate; (vii) when step (a) is performed at a pH ranging from 9-12. the primary’ carbonic acid salt comprises sodium carbonate; or (viii) any combination of (i)-(vii).

[0015] In certain embodiments of the method the carbonation reagent:

[0016] (i) is formed separately or in situ with the sodium sulfate byproduct stream; (ii) is formed prior to step (a) or during step (a); (iii) is formed in a scrubber, a pipe reactor, or in any suitable vessel or process equipment related to the sodium sulfate byproduct stream; or (iv) comprises said potassium bicarbonate and / or potassium carbonate; (v) comprises said potassium bicarbonate and / or potassium carbonate, wherein the potassium bicarbonate and / or potassium carbonate is produced by reacting carbon dioxide with potassium hydroxide(KOH), potassium oxide (K2O), or a mixture thereof; (vi) comprises said CO2 and said potassium salt; (vii) comprises said CO2 and said potassium salt, wherein said potassium salt comprises potassium hydroxide (KOH), potassium oxide (K2O), or a mixture thereof; (viii) comprises said CO2 and said potassium salt, wherein the CO2 is maintained at a pressure 1-5 bar, 1-4.5 bar, 1-4 bar, 1-3.5 bar, 1-3 bar, 1-2.8 bar, 1-2.6 bar, 1-2.5 bar, 1-2.4 bar, 1-2.2 bar, preferably 1-2 bar, 1-1.8 bar, 1-1.6 bar, 1-1.4 bar, or 1-1.2 bar; or (ix) any combination of (i)-(viii).

[0017] In certain embodiments the method further comprises:

[0018] (i) prior to step (a), optionally dissolving a solid sodium sulfate byproduct to form the sodium sulfate byproduct stream or providing the sodium sulfate byproduct stream as an aqueous solution and / or slurry; (ii) prior to step (a), adjusting the sodium sulfate byproduct stream and / or the carbonation reagents to a pH ranging from greater than 7, greater than 9. or from 7-12, 7.5-11, 8-10.5, 9-10, or 9.5-10; (iii) during step (a), agitating or mixing the sodium sulfate byproduct stream with the at least one carbonation reagent; (iv) during step (a), (b), and / or (c), maintaining a temperature of 20-60 °C, 20-55 °C, 20-50 °C, 20-45 °C, 20- 40 °C, 20-35 °C, 20-30 °C, or 25-30 °C; (iv) during step (a), optionally adding a seed cry stal of glaserite and / or potassium sulfate; (vi) during step (a), contacting the sodium sulfate byproduct stream with the carbonation reagents at a pH ranging from greater than 7, greater than 9, or from 7-12, 7.5-11, 8-10.5, 9-10, or 9.5-10; (vii) during step (a), adjusting the pH to greater than 9, greater than 10, greater than 11, or from 9-12, 9-11, 9-10.5, 9-10, or 9-9.5; or (viii) any combination of (i)-(vii), wherein the pH is optionally adjusted by addition of an alkaline reagent, sodium carbonate, sodium bicarbonate, NaOH, KOH, or K2O.

[0019] In certain embodiments of the method:

[0020] (i) the reaction mixture comprises a molar ratio of K:Na of 0.5: 1 to 2: 1, 0.6: 1 to 1.8:1. 0.7: 1 to 1.6: 1, 0.7: 1 to 1.4:1, 0.7: 1 to 1.2: 1, 0.7: 1 to 1.1:1, or preferably 0.75-1.25: 1; and / or (ii) the reaction mixture comprises a molar ratio of K:SO4 of l: l to 4: l, 1.1: 1 to 3.5: l, 1.2:1 to 3: 1, 1.3: 1 to 2.5: 1. 1.4: 1 to 2: 1, or preferably 1.5-2 5: 1.ATTY DOCKET NO. 1149704.094013

[0021] In certain embodiments the method further comprises, prior to step (a), pretreating the sodium sulfate byproduct stream to remove one or more impurities comprising one or more solid impurities, transition metal hydroxides, transition metals, heavy metals, organic impurities, polymeric impurities, or any combination thereof from the sodium sulfate byproduct stream.

[0022] In certain embodiments of the method said pretreating comprises:

[0023] (i) concentrating the sodium sulfate byproduct stream; (ii) settling, screening, and / or fdtering the solid impurities from the byproduct stream; (iii) adjusting the pH of the byproduct stream to a pH of about 6 to about 8, thereby precipitating impurities that precipitate at a pH of about 6 to about 8. and filtering off the impurities; (iv) adjusting the pH of byproduct stream further to about 8 to about 10, thereby precipitating impurities that precipitate at a pH from about 8 to about 10, and filtering off the impurities; (v) allowing metals to precipitate and / or settle as one or more low soluble salts, hydroxides and / or carbonates, and filtering off the impurities;(vi) treating the byproduct stream with one or more ion exchange methods: (vii) treating the byproduct stream with an adsorption media, such as activated carbon; or (viii) any combination of (i)-(vii), wherein any or all of (a)-(g) are performed in any order prior to contacting the sodium sulfate byproduct stream with said at least one carbonation reagent according to step (a).

[0024] In certain embodiments the method further comprises, after step (c), post-treating the solid stream comprising said one or more potassium sulfate salts, wherein post-treating comprises:

[0025] (i) washing the solid stream with water, acid, base, or any combination of the foregoing, wherein the solid stream is optionally formulated as a solid, a slurry, or a solution during post-treatment; (ii) acidifying the solid stream, optionally by addition of sulfuric acid, to a pH of 1-7. 1-6, 3-6, 5-6. 2-5, or 3-4. thereby converting residual sodium carbonate and / or sodium bicarbonate impurities into CO2, wherein the solid stream is optionally formulated as a solid, a slurry , or a solution during post-treatment; (iii) converting the solid stream comprising glaserite and / or said additional potassium sodium sulfate salts to potassium sulfate by dissolving the solid stream in water and adding potassium chloride at a molar ratio of KCl:K3Na(SO4)2 of 0.5: 1 to 2: 1 at 20-40 °C, optionally at 20-30 °C, and then separating the resulting potassium sulfate solid by solid-liquid separation, settling, centrifugation, and / or fdtration; and / or by crystallizing and separating sodium chloride from the dissolved potassium sulfate; or (iv) any combination of (i)-(iii), thereby producing a product comprising potassium sulfate.

[0026] In certain embodiments the method further comprises, after step (c), post-treating the liquid stream, wherein post-treating comprises:

[0027] (i) adjusting the liquid stream to a pH of 9-12, 8-11, 8-10, or 8-9 by addition of alkaline or NaOH, concentrating the liquid stream , settling, filtration, or a combination thereof, thereby producing said carbonic acid salts as a solid or an aqueous solution; (ii) converting sodium carbonate to sodium bicarbonate in the liquid stream by adjusting theATTY DOCKET NO. 1149704.094013 liquid stream to pH 7-9, 7.5-8.5, or preferably 8-8.5, separating the formed sodium bicarbonate by a solid-liquid separation process, and optionally recycling the liquid stream comprising unreacted K2CO3, KHCO3, and / or KOH + CO2 and a lower concentration of sodium back into step (a); (iii) converting sodium bicarbonate to sodium carbonate by subjecting the liquid stream or isolated sodium bicarbonate from the liquid stream to heat, thereby producing sodium carbonate, wherein heat comprises about 80 °C to about 200 °C for 5 min to 2 h; or (iv) any combination of (i)-(iii).

[0028] In certain embodiments of the method, the sodium sulfate byproduct stream comprises a solid, an aqueous solution, and / or an aqueous slurry' comprising a sodium sulfate byproduct derived from:

[0029] (i) any industrial process; (ii) a battery manufacturing process; (iii) a precursor cathode active material (pCAM) production process; (iv) a lithium-ion battery' recycling process; and / or (v) a mining operation, a hydrometallurgical process, a forest industry' operation, a logging operation, a wood product manufacturing process, a paper manufacturing process, or a textile manufacturing process.

[0030] In certain embodiments of the method, the sodium sulfate byproduct stream comprises byproduct from a battery manufacturing process and / or byproduct from a precursor cathode active material (pCAM) production process.

[0031] In certain embodiments of the method, the sodium sulfate byproduct stream comprises:

[0032] (i) one or more transition metal impurities comprising Ni, Mn, and / or Co at a concentration of 0.0001-50 g / L, 0.001-45 g / L, 0.01-40 g / L, 0.1-35 g / L, 0.5-30 g / L, 1-25 g / L, 2-20g / L, 4-15 g / L, 6-12 g / L, or 8-10 g / L; (ii) one or more heavy metal impurities comprising Cu, Cr, Pb, and / or Zn at concentration of 0.0001-50 g / L, 0.001-45 g / L, 0.01-40 g / L, 0. 1-35 g / L, 0.5-30 g / L, 1-25 g / L, 2-20g / L, 4-15 g / L, 6-12 g / L, or 8-10 g / L; (iii) one or more organic impurities at concentration level of dissolved organic carbon (DOC) of 1-1000 mg / L, 5-950 mg / L, 10-900 mg / L, 20-850 mg / L, 30-800 mg / L, 40-750 mg / L, 50-700 mg / L, 60-650 mg / L, 70-600 mg / L, 80-550 mg / L, 90-500 mg / L, 100-450 mg / L, 150-400 mg / L, 200-350 mg / L, or 250-300 mg / L; or (iv) any combination of (a)-(c).

[0033] In certain embodiments the method further comprises using and / or recycling the produced potassium sulfate salts, glaserite, potassium sulfate, carbonic acid salts, sodium carbonate and / or sodium bicarbonate, any combination thereof, or any element or ion therefrom back into a process stream related to:

[0034] (i) said battery' manufacturing process; (ii) said precursor cathode active material (pCAM) production process; (iii) said lithium ion battery recycling process; and / or (iv) said mining operation, said hydrometallurgical process, said forest industry operation, said logging operation, said wood product manufacturing process, said paper manufacturing process, or a textile (e.g., viscose) manufacturing process.

[0035] In certain embodiments the method further comprises:ATTY DOCKET NO. 1149704.094013

[0036] (i) recycling the produced carbonic acid salts for use as an alkaline pretreatment for removal of said metal impurities (e.g., Ca2+, Mg2+, Mn at any oxidation state, and Zn at any oxidation state) from the sodium sulfate byproduct stream or as alkaline reagent for pH adjustment; (ii) recycling the produced glaserite and / or potassium sulfate as seed crystals for formation of the solid stream comprising potassium sulfate salts; (iii) recycling any unreacted carbonation reagent back into step (a); (iv) using the produced potassium sodium sulfate salts, glaserite, and / or potassium sulfate as a fertilizer; (v) recycling the CO2 formed in posttreatment of the solid stream comprising potassium sulfate salts as said carbonation reagent, (vi) production of the carbonation reagents (e.g., CO2, potassium bicarbonate, and / or potassium carbonate) by the same plant producing the sodium sulfate byproduct stream; (vii) a cyclical process wherein one or more of said at least one carbonation reactants (e.g., CO2, potassium bicarbonate, and / or potassium carbonate) are originally obtained from the sodium sulfate byproduct stream; (viii) a cyclical process wherein the produced sodium bicarbonate and / or sodium carbonate is recycled back into said process stream related to said pCAM production process for use as (i) a base for pCAM precipitation or pCAM recycling; and / or (ii) as a pH adjustment chemical for water and / or wastewater treatment; (ix) recycling part or all of CO2 isolated from the solid stream and / or the liquid stream for use as a recycled carbonation reagent; (x) recycling the potassium in the solid stream for use as said carbonation reagent by a (1) dissolving or suspending the produced potassium sulfate salts in water or an aqueous solution comprising Ca(OH)2(aq), optionally at temperature of 30-80 °C and optionally at a pH of 7-11 or 8-10; (2) reacting the dissolved or suspended potassium sulfate salts with lime (CaO and / or Ca(OH)2(aq)) to form a calcium sulfate and / or calcium carbonate precipitate and a potassium hydroxide solution; (3) separating the potassium hydroxide solution from the calcium sulfate precipitate; (4) reacting the potassium hydroxide solution with CO2 or H2CO3 to form K2CO3; and (5) recycling the formed K2CO3 for use as said carbonation reagent; or (xi) any combination of (i)-(x).

[0037] In some embodiments, post-treatment of the produced glaserite and / or potassium sulfate glaserite stream may result in formation of CO2, which is released from the stream as a product of acidification of residual carbonate impurities.

[0038] In certain embodiments of the method, the reaction mixture comprises a molar ratio of K:Na of >l: l, 1.05: 1 to 2: 1, 1.1 :1 to 2: 1, 1.2: 1 to 1.8: 1, or 1.4: 1 to 1.6: 1 and wherein the method further comprises:

[0039] (i) recycling any unreacted carbonation reagent back into step (a); and / or (ii) separating the liquid stream comprising said carbonic acid salts and said unreacted carbonation reagent and recycling all or part of the liquid stream back into step (a).

[0040] In certain embodiments of the method:

[0041] (i) said produced sodium bicarbonate and / or sodium carbonate comprises a purity in the range of 50-100%, 60-95 wt%, 70-95%, 80-95%, or 90-95%; and / or (ii) the produced potassium sulfate comprises a purity in the range of 50-100%, 60-99%, 70-99 wt%, 80-99%, 90-99%, or 95-99%.ATTY DOCKET NO. 1149704.094013

[0042] In another aspect, the present invention provides a composition comprising:

[0043] (i) sodium bicarbonate and / or sodium carbonate produced by any of the foregoing methods; (ii) potassium sulfate produced by any of the foregoing methods; and / or (iii) glaserite produced by any of the foregoing methods.BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The invention will be described in more detail with reference to appended drawings, which are non-limiting and described in detail below.FIG 1 shows sodium sulfate byproduct production metrics.FIG 2 shows an exemplary schematic of sodium sulfate byproduct flow from industrial plants into the inventive carbonation method for treating sodium sulfate byproduct to produce potassium sulfate salts and carbonic acid salts according to Examples 1 and 2.FIG 3 A shows an exemplary graph of relative abundance of carbonic acid salts in solution vs pH and FIG3B shows an exemplary graph of predicted solubility vs temperature with carbonation conditions (pH and temperature) circled for effecting the inventive carbonation method according to Examples 1 and 2.FIG 4 shows an exemplary summary schematic of the inventive carbonation method for treating sodium sulfate byproduct to produce potassium sulfate salts and carbonic acid salts according to Examples 1 and 2.FIG 5 shows an exemplary summary schematic of the inventive carbonation method for treating sodium sulfate byproduct to produce potassium sulfate salts and carbonic acid salts according to Examples 1 and 2.FIG 6 shows an exemplary schematic of pre-treatment conditions, carbonation conditions, and post-treatment conditions of the inventive carbonation method for treating sodium sulfate byproduct with K2CO3 and / or KHCO3 to produce potassium sulfate salts and carbonic acid salts according to Examples 1 and 2.FIG 7 shows an exemplary- schematic of pre-treatment conditions, carbonation conditions, and post-treatment conditions of the inventive carbonation method for treating sodium sulfate byproduct with CO2 and KOH to produce potassium sulfate salts and carbonic acid salts according to Examples 1 and 2.DETAILED DESCRIPTION OF THE INVENTION

[0045] Before describing the invention, the following definitions are provided. Unless stated otherwise all terms are to be construed as they would be by a person skilled in the art.Detailed descriptions of one or more embodiments are provided herein. It is to be understood, however, that the invention can be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims andATTY DOCKET NO. 1149704.094013 as a representative basis for teaching one skilled in the art to employ the invention in any appropriate manner.DEFINITIONS

[0046] As used herein, all technical and scientific terms have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs unless clearly indicated otherwise.

[0047] As referred to herein, all chemicals, chemical reagents, products, salts, ions, and complex ions are understood to include either or both the anhydrous and hydrated forms thereof as commonly understood by one of ordinary skill in the art.

[0048] As used herein, the singular forms “a”, “an”, and “the” may mean “one” but also include plural referents such as “one or more” and “at least one” unless the context clearly dictates otherwise. All technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary' skill in the art to which this invention belongs unless clearly indicated otherwise.

[0049] As used herein, the term “or” in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.”

[0050] As used herein the term “or combinations thereof as used herein refers to all permutations and combinations of the listed items preceding the term unless stated otherwise.BATTERY PRODUCTION AND BYPRODUCT TREATMENT

[0051] As used herein, the term “adsorption media” can refer to activated carbon, zeolite, clays, activated alumina, silica, polymeric adsorbents and other adsorption media known in the art.

[0052] As used herein, the terms “aqueous suspension”, “aqueous slurry”, or “slurry” can refer to a heterogeneous mixture of a fluid, such as an aqueous fluid, that contains insoluble or sparingly soluble solid particles. Suspensions and slurries of the present invention comprise precipitates, crystals, large particles sufficiently large to completely settle under gravity, and / or small solid particles, such as colloidal particles, which do not completely settle or take a long time to settle completely under gravity.

[0053] As used herein, the term “concentrating” or “solids concentrating” can refer to any process by which a feed stream, byproduct stream, sodium sulfate byproduct stream, solution, solid-liquid mixture, slurry-, or dispersion is treated to reduce liquid volume, thereby increasing the concentration of solutes, total suspended solids, and / or total solids in the concentrated stream. Concentration may be effected by removing all or part of the liquid, such as by gravity or centrifugal thickening, hydrocy cloning, or evaporation. In certain embodiments, concentrating can result in crystallization, precipitation, and / or agglomeration, of solid impurities, which can be subsequently removed by solid-liquid separation. In certain embodiments, concentrating can result in cry stallization, precipitation, and / or agglomeration,ATTY DOCKET NO. 1149704.094013 of one or more desired solids, such as (i) potassium sulfate salts, potassium sulfate, and / or glaserite or (ii) carbonic acid salts, sodium carbonate, and / or sodium bicarbonate, which can be subsequently isolated by solid-liquid separation.

[0054] As used herein, the term ‘‘glaserite conversion’' can refer to any process by which glaserite (KsNa(SO4)2), aphthitalite, or any potassium sodium sulfate salt is converted to potassium sulfate (K2SO4). In certain embodiments, glaserite conversion comprises converting a solid stream comprising glaserite and / or said additional potassium sodium sulfate salts to potassium sulfate by dissolving the solid stream in water and adding potassium chloride at a molar ratio of KCl:KaNa(SO4)2 of 0.5: 1 to 2:1 at 20-40 °C, optionally at 20-30 °C, and then separating the resulting potassium sulfate solid by solid-liquid separation, settling, centrifugation, and / or filtration; and / or by crystallizing and separating sodium chloride from the dissolved potassium sulfate.

[0055] As used herein, the terms “liquid stream” and “overflow” are used interchangeably and can refer to a liquid phase comprising a supernatant, filtrate, or liquid overflow from a solidliquid separation process. A liquid stream can comprise any liquid, solution, or slurry' formed from a solid-liquid separation process. A liquid stream can comprise a reduced amount of suspended solids compared to the feed stream for the solid-liquid separation process. In certain embodiments, the liquid stream contains residual particulate matter from the solid stream. In certain embodiments, the liquid stream contains dissolved or partially dissolved material that can precipitate or crystallize to form a solid material, which can then be subjected to a second solid-liquid separation process. Further as used herein, the terms “liquid stream” and “overflow-” can refer to the flow or stream of less dense material in a solid-liquid separation process. For example, the overflow' can move from one stage of a process to another and comprise less dense and / or particulate carrying liquid.

[0056] As used herein, the term “post-treating” or “post-treatment” are used interchangeably to refer to one or more methods for treating a liquid stream and / or a solid stream produced according to the inventive carbonation method. In certain embodiments, post-treatment of the liquid stream comprises precipitation or crystallization of carbonic acid salts, followed bysettling and / or filtration. In certain embodiments, post-treatment of the liquid stream comprises adjusting the liquid stream to a pH of 9-12, 8-11, 8-10, or 8-9 by addition of alkaline or NaOH, concentrating the liquid stream, settling, filtration, or a combination thereof, thereby producing said carbonic acid salts as a solid or an aqueous solution. In certain embodiments, post-treatment of the liquid stream comprises converting sodium carbonate to sodium bicarbonate in the liquid stream by adjusting the liquid stream to pH 7-9, 7.5-8.5, or preferably 8-8.5, separating the formed sodium bicarbonate by a solid-liquid separation process. In certain embodiments, post-treatment of the liquid stream comprises converting sodium bicarbonate to sodium carbonate by subjecting the liquid stream or isolated sodium bicarbonate from the liquid stream to heat, thereby producing sodium carbonate, wfierein said heat comprises about 80 °C to about 200 °C. In certain embodiments, post-treatment of the liquid stream comprises optionally concentrating and allowing a second crop of crystals or precipitate to form.ATTY DOCKET NO. 1149704.094013

[0057] As used herein, the term "precursor cathode active material’" (pC AM) can refer to cathode precursor materials used to produce a cathode active material. For example, the precursor cathode active material can be combined with lithium hydroxide to produce a cathode active material (CAM) for battery production. Byproduct from pCAM and / or battery manufacturing comprises sodium sulfate as a primary component. In certain embodiments sodium sulfate is present in the pCAM byproduct stream at 0.1-40 wt%, 0.5-30 wt%, 1-20 wt%, 2-18 wt%, 4-16 wt%, 5-15 wt%, 6-14 wt%, 8-12 wt%, or 9-10 wt%.

[0058] As used herein, the term “pre-treating’" or “pre-treatment” are used interchangeably to refer to one or more methods for treating a sodium sulfate byproduct stream prior to effecting the inventive carbonation method. In certain embodiments “pre-treatment” comprises removing one or more impurities comprising one or more solid impurities, transition metal hydroxides, transition metals, heavy metals, organic impurities, polymeric impurities, or any combination thereof from the sodium sulfate byproduct stream.

[0059] As used herein, the term “recycling” refers to (i) isolating one or more chemicals produced according to the inventive carbonation method and reusing said chemicals in a subsequent application of the inventive carbonation method, also referred to as a “circular"’ or “cyclical” process; and / or (ii) isolating one or more chemicals produced according to the inventive method and reusing said chemicals as a raw material or fertilizer in a separate process. In certain embodiments, a liquid or solid stream comprising sodium carbonate (NaiCOs) and / or sodium bicarbonate (NaHCCh) is subjected to acidification, such as by addition of H2SO4, during a post-treatment step to produce carbon dioxide (CO2), which is then captured an reused as a carbonation reagent in a subsequent application of the inventive carbonation method. CO2 can be generated and recycled in this manner from the liquid stream comprising carbonic acid salts (e.g., as the major component) or from a solid stream comprising potassium sulfate salts and carbonic acid salt impurities. In certain embodiments, carbonic acid salt products are recycled to adjust the pH of the sodium sulfate byproduct stream for removal of metal impurities during pre-treatment. In certain embodiments, glasente and / or potassium sulfate product(s) are used as seed crystals in carbonation. In certain embodiments, carbonic acid salt product are recycled back to a production plant for mining, battery , textile industry7.

[0060] As used herein, the term “seed” or “seed crystal” can refer to a small piece of crystalline material, a single crystal, or a polycrystal material from which a larger ciystal of ty pically the same material is grown. A seed crystal can be added to an industrial stream, a solution, suspension, dispersion, or a supersaturated solution to initiate, promote nucleation, or increase the rate of crystallization and / or precipitation of a desired material. In certain embodiments, a seed crystal may be added to a sodium sulfate byproduct stream or a pretreated sodium sulfate byproduct stream. In certain embodiments, the seed crystal comprises potassium sulfate (K.2SO4), glaserite, (K3Na(SO4)2), sodium carbonate (Na2COs), or sodium bicarbonate (NaHCCh) and the corresponding desired material comprises potassium sulfate (K2SO4), glaserite, (KaNa(SO4)2), sodium carbonate (NaiCO?), or sodium bicarbonate (NaHCOs). respectively. In certain embodiments, the seed crystal comprises potassiumATTY DOCKET NO. 1149704.094013 sulfate (K2SO4), glaserite, (KsNa(SO4)2), sodium carbonate (N 32603). or sodium bicarbonate (NaHCO.3) that has been isolated from or recycled from a sodium sulfate byproduct stream by treatment with one or more carbonation reagents according to the present invention.

[0061] As used herein, the term ‘‘solid-liquid separation"’ can refer to the separation of two phases, a solid phase and a liquid phase, from a suspension, slurry, or dispersion. As used herein, the liquid phase from a solid-liquid separation is referred to interchangeably as a “liquid stream”, “overflow”, or “supernatant” or “filtrate” . As used herein, the solid phase from a solid-liquid separation is referred to interchangeably as a “solid stream"’ or “underflow”, or “filter cake”. Solid-liquid separations encompass a wide range of processes, including but not limited to, screening through a screen or mesh, settling of a precipitate, crystals, or solids (i.e. , gravity settling of solids), sedimentation, filtration (i.e., gravity filtration, pressure filtration, vacuum filtration, centrifugal filtration), centrifugation, or any combination thereof. Solid-liquid separations are effected by equipment, including but not limited to, gravity settlers, e.g., clarifiers, deep thickeners, lamella separators, settling tanks, lagoons, thickeners; sedimenting centrifuges, e.g., tubular bowl, skimmer pipe, disc, scroll discharge; hydrocyclones, e.g., conical, circulating bed; classifiers, e.g., hydraulic, mechanical, screens, sieve bends; gravity filters, e.g., deep bed. Nutsche; line filters, e.g., cartridges, strainers; pressure filters, e.g., continuous pressure, diatomaceous earth, fiber bed, filter press, horizontal element, pressure Nutsche, vertical element, sand, sheet filter, tubular element; filters with compression, e.g., belt press, membrane plate and frame, screw press, variable volume filter (e.g., tube); vacuum filters, e.g., top / bottom fed drum, disc, leaf, belt, pan, table, precoat drum; filter thickeners or crossflow filters, e.g., delayed cake, dynamic or high shear microfilters, low shear microfilters / ultrafilters; filtering centrifuges, e.g., basket, pendulum, oscillating, tumbling, plough / peeler, pusher, worm screen; flotation; magnetic filters, e.g., low gradient (drum, grid or belt), high gradient, by any solid-liquid separation equipment known in the art, or any combination thereof.

[0062] As used herein, the terms “solid stream” and "‘underflow” are used interchangeably and can refer to a solid phase comprising an isolated solid, a crude solid, a solid slurry, isolated solid impurities, a settled solid, a screened solid, or a filter cake from a solid-liquid separation process. A solid stream can comprise any solid or solid slurry formed from a solidliquid separation process. A solid stream can comprise an increased amount of solids or suspended solids compared to the feed stream for the solid-liquid separation process. In certain embodiments, the solid stream contains residual material from the liquid stream. Further as used herein, the terms “solid stream” and “underflow” can refer to the flow or stream of more dense material in a solid-liquid separation process. For example, the underflow can move from one stage of a process to another and comprise more dense and / or particulate carrying liquid.

[0063] As used herein, the term “stream” can refer to a material, or a flow of material derived from or moving through a process, such as a production process, manufacturing process, and / or chemical or biochemical reaction. For example, the material can be a solution, a slurry’, a liquid, gas, solid, or any combination thereof. In certain embodiments, a stream canATTY DOCKET NO. 1149704.094013 be fed as a “feed stream” into any industrial process relating to sodium sulfate byproduct processing or any industrial process referred to herein. In certain embodiments, a stream can comprise a “byproduct stream” comprising a secondary product stream, a waste stream, or a wastewater stream from any industrial process. In certain embodiments, a stream can comprise a sodium sulfate stream, a sodium sulfate byproduct stream a sodium sulfate waste stream, or a sodium sulfate wastewater stream from any industrial process. In certain embodiments, a stream can comprise a sodium sulfate stream comprising solid sodium sulfate. In certain embodiments, the solid sodium sulfate can be collected in a warehouse, such as at a battery plant for several months, and / or trucked to an offsite location, and / or dissolved before treatment.

[0064] As used herein, the term “byproduct” can refer to any secondary product derived from any industrial process, production process, manufacturing process, and / or chemical or biochemical reaction. For example “byproduct” can refer to any aqueous solution, aqueous slurry, solid, or liquid material flows and / or streams of byproduct from its source through to recovery, recycling, and / or disposal. For example, byproduct can refer to a solid byproduct, a liquid byproduct, an aqueous byproduct, a byproduct solution, a byproduct slurry, a gaseous byproduct, a waste stream, or wastewater. For example, the source can be an industrial facility. For example, the industrial facility' can comprise a pulp and paper facility, a textile facility, a mining facility, or a battery production facility. In certain embodiments, byproduct stream refers to any solid material, liquid material, or mixture thereof produced as byproduct from any process relating to battery manufacturing and / or recycling, pulp and paper manufacturing and / or or recycling, or textile manufacturing and / or or recycling. In certain embodiments, byproduct stream refers to a sodium sulfate byproduct stream comprising a solution, suspension, or slurry that comprises sodium sulfate. In certain embodiments “byproduct” refers to an “aqueous byproduct” comprising an aqueous solution and / or slurry of a secondary product, such as sodium sulfate, and optionally further comprising other solid, liquid, or solution phase impurities. In certain embodiments, the “byproduct” comprises solid sodium sulfate, a sodium sulfate solution, or a sodium sulfate slurry'. In certain embodiments sodium sulfate is present in the sodium sulfate byproduct stream at 0. 1-40 wt%, 0.5-30 wt%, 1-20 wt%, 2-18 wt%, 4-16 wt%, 5-15 wt%, 6-14 wt%, 8-12 wt%. or 9-10 wt%.

[0065] In certain embodiments the sodium sulfate byproduct stream further comprises solid impurities, heavy metal impurities, transition metal impurities, transition metal hydroxides, polymeric impurities, organic impurities, or any combination thereof. Heavy metals and transition metals in said metal impurities may be any oxidation state known in the art, such as ranging from zero to +6 or higher.

[0066] In certain embodiments the sodium sulfate byproduct stream comprises one or more “transition metal impurities” comprising Ni. Mn, and / or Co at a concentration of 0.0001-50 g / L, 0.001-45 g / L, 0.01-40 g / L, 0.1-35 g / L, 0.5-30 g / L, 1-25 g / L, 2-20g / L, 4-15 g / L, 6-12 g / L, or 8-10 g / L. Transition metal impurities may comprise any oxidation state, salt form, or coordination state known in the art.ATTY DOCKET NO. 1149704.094013

[0067] In certain embodiments the sodium sulfate byproduct stream comprises one or more “heavy metal impurities” comprising Cu, Cr, Pb, and / or Zn at concentration of 0.0001-50 g / L, 0.001-45 g / L, 0.01-40 g / L, 0.1 -35 g / L, 0.5-30 g / L, 1 -25 g / L, 2-20g / L, 4-15 g / L, 6-12 g / L, or 8-10 g / L. Heavy metal impurities may comprise any oxidation state, salt form, or coordination state known in the art.

[0068] In certain embodiments the sodium sulfate byproduct stream comprises one or more “metal impurities” comprising one or more alkaline earth metals, one or more transition metals, and / or one or more heavy metals, including but not limited to Ca. Mg, Fe, and / or Al, at concentration of 0.0001-50 g / L, 0.001-45 g / L, 0.01-40 g / L, 0.1-35 g / L, 0.5-30 g / L, 1-25 g / L, 2-20g / L, 4-15 g / L, 6-12 g / L, or 8-10 g / L. The metal impurities may comprise any oxidation state, salt form, or coordination state known in the art.

[0069] In certain embodiments the sodium sulfate byproduct stream comprises one or more “organic impurities” at concentration of dissolved organic carbon (DOC) of 1-1000 mg / L, 5- 950 mg / L, 10-900 mg / L, 20-850 mg / L, 30-800 mg / L, 40-750 mg / L, 50-700 mg / L, 60-650 mg / L, 70-600 mg / L, 80-550 mg / L, 90-500 mg / L, 100-450 mg / L, 150-400 mg / L, 200-350 mg / L, or 250-300 mg / L. Organic impurities may comprise any organic chemical or polymeric material known the art.CARBONATION REAGENTS AND PRODUCTS

[0070] As used herein, the terms “carbonation” and “carbonate conversion” are used interchangeably to refer to treatment of a sodium sulfate byproduct stream according to the inventive carbonation method.

[0071] As used herein, the terms “carbonation conditions” and “carbonate conversion conditions” are used interchangeably to refer to carbonation reagents and reaction conditions (e.g., pH and temperature) for effecting a process by which a sodium sulfate by product stream or a pre-treated sodium sulfate byproduct stream is treated with a “carbonation reagent” to produce (i) a solid stream comprising one or more potassium sulfate salts and (ii) a liquid stream comprising one or more carbonic acid salts via a double displacement reaction. “Carbonation conditions” also refers to the specific reaction conditions (e.g., temperature and pH) under which the reaction is performed.

[0072] As used herein, the term “carbonation reagent” can refer to (i) potassium bicarbonate (KHCO3) and / or potassium carbonate (K2CO3); or (ii) carbon dioxide (CO2) and a potassium salt comprising potassium hydroxide (KOH) or potassium oxide (K2O).

[0073] Carbonation chemistry according to the present invention can be exemplified by the following equation for treating a sodium sulfate byproduct stream with (i) potassium carbonate (K2CO3) to produce potassium sulfate (K2SO4 (s)):Na2SO4 (aq) + K2CO3 (aq) —> K2SO4 (s) + Na2CO3 (aq)

[0074] Carbonation chemistry according to the present invention can be exemplified by the following equation for treating a sodium sulfate byproduct stream with (i) potassium carbonate (K2CO3) to produce glaserite (K3Na(SO4)2 (s)):ATTY DOCKET NO. 1149704.0940132Na2SO4(aq) + 2K2CO3 (aq) K3Na(SO )2(s) + Na2CC>3 (aq) + NaKCCh (aq)

[0075] Carbonation chemistry according to the present invention can be exemplified by the following equations for treating a sodium sulfate byproduct stream with (ii) carbon dioxide (CO2) and KOH to produce potassium sulfate (K2SO4(s)):CO2 (g) + H2O H2CO3 (aq)H2CO3 (aq) + 2KOH (aq) K2CO3 (aq) + 2H2ONaiSOi (aq) + K2CO3 (aq) — K2SQ4(s) + Na2CO3 (aq)CO2 (g) + 2KOH (aq) + Na2SO4(aq) K2SO4(s) + Na2CO3 (aq) + H2O

[0076] Carbonation chemistry according to the present invention can be exemplified by the following equations for treating a sodium sulfate byproduct stream with (ii) carbon dioxide (CO2) and KOH to produce glaserite (KsNa(SO4)2(s)):2CO2(g) + 2H2O 2H2CO3 (aq)2H2CO3 (aq) + 4K0H (aq) 2K2CO (aq) + 4H2O2Na2SQ4(aq) + 2K2CO3 (aq) K3Na(SQ4)2(s) + Na2CQ3(aq) + NaKCOs (aq) 2CO2(g) + 4K0H (aq) + 2Na2SO4(aq) K3Na(SO4)2(s) + Na2CO3(aq) + NaKCOs (aq) + 2H2O

[0077] As used herein, the term “carbonic acid salts” can refer to sodium carbonate (Na2COs), sodium bicarbonate (NaHCCh), or a mixture thereof.

[0078] As used herein, the term “glaserite” refers to a potassium sodium sulfate salt of the form KsNa(SO4)2 or KeNa2(SO4)4.

[0079] As used herein, the term “potassium sulfate salts” can refer to potassium sulfate (K2SO4); potassium bisulfate (KHSO4); glaserite (K3Na(SO4)2); one or more additional potassium sodium sulfate salts of the form KnNam(SO4)2, wherein n and m are between 1 and 3; one or more additional potassium sodium sulfate salts of the form KxNay(SO4)4, wherein x and y are between 1 and 7; a potassium sulfate mineral comprising aphthitalite; or any combination of the foregoing. “Potassium sulfate salts” can refer to a single salt or a mixture of salts, a purified single salt or mixture of salts, or a single salt or mixture of salts optionally containing one or more impurities.UNITS

[0080] As used herein, the term “ppm” refers to parts per million, mass fraction of a solute in a solvent, or dry mass (mg) of added material (e.g., additive, solute, and / or particle) per mass (kg) of solvent, with units of mg / kg. For aqueous solutions, ppm refers to dry' mass (mg) of added solute per volume (L) of water, with units of mg / L.

[0081] As used herein, the term “wt %” refers to dry mass of material (e.g., additive, solute, and / or particle) per mass (kg) of solvent, multiplied by 100%.DESCRIPTION OF THE INVENTION

[0082] The present invention provides carbonation methods for treating industrial byproduct streams comprising sodium sulfate with one or more carbonation reagents, including but not limited to (i) potassium bicarbonate and / or potassium carbonate; or (ii) carbon dioxide (CO2)ATTY DOCKET NO. 1149704.094013 and a potassium salt, thereby producing (i) a solid phase comprising one or more potassium sulfate salts and (ii) a liquid phase comprising carbonic acid salts in solution. The solid and liquid phases are separated by solid-liquid extraction.

[0083] The one or more potassium sulfate salts comprise potassium sulfate (K2SO4), glaserite, or other sodium potassium sulfate salts. Potassium sulfate (K2SO4) can be maximized by post-treating with one or more glaserite conversion methods. The potassium sulfate stream is purified and used as a fertilizer.

[0084] The carbonic acid salts comprise sodium carbonate (Na2COs) and / or sodium bicarbonate (NaHCCh). Na2CCh yield (instead of NaHCCh) is maximized by using pH > 9. NaHCChyield (instead of NaiCCh) is maximized by using pH < 9.The carbonic acid salts are recycled internally, e.g., are used as pH adjustment chemical, used to produce CO2, or sold elsewhere.

[0085] The present invention also provides processes for isolating the aforementioned salts from industrial byproduct streams. The present invention also provides cyclical processes for recovering and recycling reagents for producing the aforementioned salts from the industrial byproduct streams and from product streams containing the aforementioned salts.Conversion of sodium sulfate byproduct to potassium sulfate salts and carbonic acid salts

[0086] In one aspect, the present invention provides a method of producing (i) one or more potassium sulfate salts and (ii) one or more carbonic acid salts from a sodium sulfate byproduct stream, the method comprising at least steps (a)-(c) as set forth below:

[0087] (a) contacting the sodium sulfate byproduct stream with at least one carbonation reagent, thereby producing a solid stream comprising said potassium sulfate salts and a liquid stream comprising said carbonic acid salts, wherein the carbonation reagent comprises (i) potassium bicarbonate and / or potassium carbonate; or (ii) carbon dioxide (CO2) and a potassium salt; (b) isolating the solid stream comprising potassium sulfate salts; and (c) isolating the liquid stream comprising said carbonic acid salts.

[0088] In certain embodiments of the method:

[0089] (i) step (b) comprises isolating the solid stream from the liquid stream by solid-liquid separation, optionally comprising settling, centrifugation, and / or filtration to form an isolated solid: (ii) the solid stream comprises said potassium sulfate salts and optionally a residual amount of said carbonic acid salts; (iii) the liquid stream comprises said carbonic acid salts and optionally a residual amount of said potassium sulfate salts; (iv) said potassium sulfate salts comprise potassium sulfate (K2SO4); glaserite (KsNa(SO4)2); a mixture of potassium sulfate and glaserite; one or more additional potassium sodium sulfate salts of the form KnNam(SO4)2, wherein n and m are between 1 and 3; one or more additional potassium sodium sulfate salts of the form KxNay(SO4)4, wherein x and y are between 1 and 7; or any combination of the foregoing; (v) said carbonic acid salts comprise sodium carbonate, sodium bicarbonate, or a mixture thereof; (vi) when step (a) is performed at a pH ranging from aboutATTY DOCKET NO. 1149704.0940137-9, the primary carbonic acid salt comprises sodium bicarbonate; (vii) when step (a) is performed at a pH ranging from about 9-12, the primary carbonic acid salt comprises sodium carbonate; or (viii) any combination of (i)-(vii).

[0090] In some embodiments, the residual carbonic acid salts comprise at least sodium carbonate and / or sodium bicarbonate.

[0091] In some embodiments, the residual amount of said carbonic acid salts comprises 0.01-0.8-2 wt%, or 0.9-1 wt%. In some embodiments, the residual amount of said potassium sulfate salts comprises 0.01 -10 wt%, 0.1-9 wt%, 0.2-8 wt%, 0.3-7 wt%, 0.4-6 wt%, 0.5-5 wt%. 0.6-4 wt%. 0.7-3 wt%. 0.8-2 wt%, or 0.9-1 wt%.

[0092] In some embodiments, the potassium sulfate salts comprise potassium bisulfate (KHSC ), one or more additional potassium sodium sulfate salts of the form KnNamHi(SO4)2, wherein n, m, and i are between 1 and 3; one or more additional potassium sodium sulfate salts of the form KxNayHz(SO4)4, wherein x. y, and z are between 1 and 7; a mixture of potassium sulfate and any combination of the foregoing; a mixture of potassium sulfate, glaserite, and any combination of the foregoing.

[0093] In certain embodiments of the method the carbonation reagent:

[0094] (i) is formed separately or in situ with the sodium sulfate byproduct stream; (ii) is formed prior to step (a) or during step (a); (iii) is formed in a scrubber, a pipe reactor, or in any suitable vessel or process equipment related to the sodium sulfate byproduct stream; or (iv) comprises said potassium bicarbonate and / or potassium carbonate; (v) comprises said potassium bicarbonate and / or potassium carbonate, wherein the potassium bicarbonate and / or potassium carbonate is produced by reacting carbon dioxide with potassium hydroxide(KOH), potassium oxide (K2O). or a mixture thereof; (vi) comprises said CO2 and said potassium salt; (vii) comprises said CO2 and said potassium salt, wherein said potassium salt comprises potassium hydroxide (KOH), potassium oxide (K2O), or a mixture thereof; (viii) comprises said CO2 and said potassium salt, wherein the CO2 is maintained at a pressure about 1-5 bar, about 1-4.5 bar, about 1-4 bar, about 1-3.5 bar, about -3 bar, about 1- 2.8 bar, about 1-2.6 bar, about 1-2.5 bar, about 1-2.4 bar, about 1-2.2 bar, preferably about 1- 2 bar, about 1-1.8 bar, about 1-1.6 bar, about 1-1.4 bar, about 1-1.2 bar, or about 1-1.1 bar; or (ix) any combination of (i)-(viii).

[0095] In some embodiments, the carbonation reagent is formed prior separately by combining CO2 and a potassium salt, potassium hydroxide(KOH), potassium oxide (K2O), or a mixture thereof. In some embodiments, the potassium salt comprises KOH.

[0096] In certain embodiments, the sodium sulfate byproduct stream comprises a solid sodium sulfate byproduct, which can be dissolved to form a solution or a slurry' prior to step (a).

[0097] In certain embodiments the method further comprises:

[0098] (i) prior to step (a), optionally dissolving a solid sodium sulfate byproduct to form the sodium sulfate byproduct stream or providing the sodium sulfate byproduct stream as anATTY DOCKET NO. 1149704.094013 aqueous solution and / or slurry; (ii) prior to step (a), adjusting the sodium sulfate byproduct stream and / or the carbonation reagents to a pH ranging from greater than 7, greater than 9, or from about 7-12, about 7.5-1 1 , about 8-10.5, about 9-10, or about 9.5-10; (iii) during step (a), agitating or mixing the sodium sulfate byproduct stream with the at least one carbonation reagent; (iv) during step (a), (b), and / or (c), maintaining a temperature of about 20-60 °C, about 20-55 °C, about 20-50 °C, about 20-45 °C, about 20-40 °C, about 20-35 °C, about 20- 30 °C, or about 25-30 °C; (v) during step (a), optionally adding a seed crystal of glaserite and / or potassium sulfate; (vi) during step (a), contacting the sodium sulfate byproduct stream with the carbonation reagents at a pH ranging from greater than 7, greater than 9. or from about 7-12. about 7.5-11, about 8-10.5, about 9-10, or about 9.5-10; (vi) during step (a), adjusting the pH to greater than 9, greater than 10, greater than 11, or from about 9-12, about 9-11, about 9-10.5, about 9-10, or about 9-9.5; or (viii) any combination of (i)-(vii), wherein the pH is optionally adjusted by addition of an alkaline reagent, sodium carbonate, sodium bicarbonate, NaOH, KOH. or K2O.

[0099] In some embodiments, the carbonation reaction can first be run at an elevated temperature, and subsequently left to mix in the reactor at room temperature, thereby precipitating carbonic acid salts from the liquid stream. In embodiments, the elevated temperature can comprise a temperature greater than about 20 °C and room temperature can comprise about 20 °C.

[0100] In some embodiments, the seed crystal of glaserite and / or potassium sulfate is obtained from the solid stream or a previously formed solid stream.

[0101] In certain embodiments of the method:

[0102] (i) the reaction mixture comprises a molar ratio of K:Na of about 0.5: 1 to about 2:1, about 0.6: 1 to about 1.8: 1 , about 0.7: 1 to about 1.6: 1 , about 0.7: 1 to about 1.4: 1, about 0.7:1 to about 1.2: 1, about 0.7: 1 to about 1.1 : 1, or preferably about 0.75: 1 to about 1.25: 1. or about 0.75: 1 to about 0.99: 1; and / or (ii) the reaction mixture comprises a molar ratio of K:SO4 of about 1: 1 to about 4: 1, about 1.1: 1 to about 3.5: 1, about 1.2: 1 to about 3: 1, about 1.3: 1 to about 2.5: 1, about 1.4: 1 to about 2: 1, or preferably about 1.5: 1 to about 2.5: 1, or about 1.5:1 to about 1.99: 1. In some preferred embodiments, the reaction mixture comprises a molar excess of Na2SO4 compared to K2CO3, corresponding to a molar ratio of K:Na of about 0.75: 1-0.99: 1, 0.8: 1-0.99: 1, 0.9: 1-0.99: 1, or 0.95: 1-0.99: 1 and a molar ratio of KSC of about 1.5: 1-1.99:1, 1.6: 1-1.99:1, 1.7: 1-1.99:1, 1.8: 1-1.99:1, 1.9: 1-1.99:1, or 1.95: 1-1.99:1.Pre-treatment of sodium sulfate byproduct

[0103] In certain embodiments the method further comprises, prior to step (a), pretreating the sodium sulfate byproduct stream to remove one or more impurities comprising one or more solid impurities, transition metal hydroxides, transition metals, heavy metals, organic impurities, polymeric impurities, or any combination thereof from the sodium sulfate byproduct stream.

[0104] In certain embodiments of the method said pretreating comprises:ATTY DOCKET NO. 1149704.094013

[0105] (i) concentrating the sodium sulfate byproduct stream, thereby forming said solid impurities and separating the solid impurities by solid-liquid separation; (ii) settling, screening, and / or filtering the solid impurities from the byproduct stream; (iii) adjusting the pH of the byproduct stream to a pH of about 6 to about 8. thereby precipitating impurities that precipitate at a pH of about 6 to about 8. and removing the impurities by solid liquid separation; (iv) adjusting the pH of byproduct stream further to about 8 to about 10, thereby precipitating impurities that precipitate at a pH from about 8 to about 10, and removing the impurities by solid liquid separation; (v) allowing metals to precipitate and / or settle as one or more low soluble salts, hydroxides and / or carbonates, and removing the impurities by solid liquid separation;(vi) treating the byproduct stream with one or more ion exchange methods; (vii) treating the byproduct stream with an adsorption media or activated carbon; or (viii) any combination of (i)-(vii), wherein any or all of (a)-(g) are performed in any order prior to contacting the sodium sulfate byproduct stream with said at least one carbonation reagent according to step (a).

[0106] In some embodiments, the sodium sulfate byproduct stream can be concentrated before or after treatment. In some embodiments, the concentration of the compounds in the byproduct stream can be used to determine whether the byproduct stream is concentrated before or after pre-treatment. For example, if the metal concentration is less than about 10 mg / L, the byproduct stream can be concentrated before pre-treatment. In some embodiments, water hardness can be used to determine whether the byproduct stream is concentrated before or after pre-treatment. For example, if the water hardness is less than about 200 mg / L, the byproduct water can be concentrated before pretreatment. In embodiments, metal quantification in the byproduct stream can occur before pre-treatment, after pre-treatment, or both before and after pre-treatment.

[0107] In some embodiments, the solid liquid separation methods comprise filtration, settling, centrifugation, flotation, and / or screening. In some embodiments of the invention the sodium sulfate byproduct stream is pretreated before or after concentrating.

[0108] In some embodiments of the method said impurities that precipitate at a pH of about 2.4 to about 8, about 3 to about 8, about 3.5 to about 8, about 4 to about 8, about 4.5 to about 8, about 5 to about 8, about 5.5 to about 8, about 6 to about 8, about 6-8, about 6-7.5, about 6- 7, or about 6.5-7 comprise a first set of impurities selected from the group consisting of transition metal salts, transition metal oxides, transition metal hydroxides, organic material, polymeric material, and preferably one or more aluminum salts and / or iron salts or any combination thereof, wherein the aluminum salts and / or iron salts precipitate as one or more corresponding metal oxides or metal hydroxides comprising Fe(OH)2, Fe(OH)?, and / or Al(OH)3.or any combination thereof.

[0109] In some embodiments of the method said impurities that precipitate at a pH of about >6-11, >6.5-11, >7-11, about 7.5-10.5, about 8-10, about 8-9.5, about 8.5-9, or about 8-9, or about 8 to about 10 comprise a second set of impurities comprising alkaline earth metals, remaining transition metals, and / or heavy metal impurities to precipitate as one or more metalATTY DOCKET NO. 1149704.094013 hydroxides comprising Ca(OH)2, Mg(0H)2, Ni(0H)2, Mn(0H)2, Co(OH)2, Cr(Of I).< Fe(OH)s, Pb(OH)2, Zn(0H) 2, and / or Cu(0H)2); and / or (ii) allowing metals to precipitate as low soluble carbonates selected from the group consisting of CaCCh, MgCCh MgCCh-3 H2O, MnCCh, FeCOs, PbCCh. N1CO3. ZnCO or ZnCCh FbO.

[0110] In some embodiments, the pH adjustment can occur in a settler, clarifier, or thickener. For example, as a result of the pH increase, the metals in the byproduct stream can form metal hydroxides which can more easily precipitate. In embodiments, longer retention times (e.g., 1 to 2 hours) in settlers can allow small, agglomerated metal hydroxides to precipitate. In some embodiments, a flocculant can be added to increase the settling rate. Non-limiting, exemplary flocculants comprise polyacrylamides, polyacrylamide co-polymers. starches, celluloses, carboxymethyl cellulose, chitosan, or any combination thereof. In embodiments, the flocculant concentration can comprise about 0.1-1 wt% or 0.1-1000 ppm.

[0111] In some embodiments of the method said pretreating comprises: (i) concentrating the sodium sulfate byproduct stream from an initial concentration ranging from about less than 15 wt%, about less than 10 wt%, 1-15 wt%, 1-12 wt%, 1-10 wt%, 2-10 wt%. 4-10 wt%, 6-10 wt%, or 8-10 wt% to a final concentration ranging from greater than about 20 wt%, 20-50 wt%, 20-40 wt%, 20-35 wt%, 20-30 wt%, or20-25 wt%, wherein concentrating optionally comprises evaporating the sodium sulfate byproduct stream or comprises use of an evaporator: (ii) allowing one or more solid impurities to settle and / or filtering said one or more solid impurities from the sodium sulfate byproduct stream; (iii) adjusting the pH of the sodium sulfate byproduct stream from an initial pH, optionally ranging from less than about 6, 3-<6, 4-<6, or 5-<6, to a pH ranging from about 6-8, 6-7.5, 6-7, or 6.5-7 and then precipitating a first set of impurities selected from the group consisting of transition metal salts, transition metal oxides, transition metal hydroxides, organic material, polymeric material, and preferably one or more aluminum salts and / or iron salts, wherein the aluminum salts and / or iron salts precipitate as one or more corresponding metal oxides or metal hydroxides comprising Fe(OH)2, Fe(OH)3, Al(OH)s, and / or A1(OH)4; (iv) adjusting the pH of the sodium sulfate byproduct stream to a pH ranging from > about 7-11, 7.5-10.5, 8-10, 8- 9.5, 8.5-9, or 8-9 and then (i) allowing a second set of impurities comprising alkaline earth metals, remaining transition metals, and / or heavy metal impurities to precipitate as one or more metal hydroxides comprising Ca(OH)2, Mg(OH)2, Ni(OH)2, Mn(0H)2, Co(OH)2, Cr(OH)3, Fe(OH)3, Pb(OH)2, Zn(OH)2, and / or Cu(OH)2); and / or (ii) allowing metals to precipitate as low soluble carbonates selected from the group consisting of CaCOs. MgCO?. MgCOsA H2O, MnCOs, FeCOs, PbCO3, NiCOs, ZnCOs or ZnCO3-H2O; (v) optionally treating the sodium sulfate byproduct stream with one or more ion exchange methods; (vi) optionally treating the sodium sulfate byproduct stream with one or more adsorption media, such as activated carbon, zeolite, clays, activated alumina, silica, polymeric adsorbents and / or other adsorption media known in the art, followed by filtration; or (vii) any combination of (i)-(vi), wherein any or all of (i)-(vii) are performed in any order prior to contacting the sodium sulfate byproduct stream with said at least one carbonate conversion reagent according to step (a).ATTY DOCKET NO. 1149704.094013Post-treatment of solid stream and liquid stream

[0112] In certain embodiments the method further comprises, after step (c), post-treating the solid stream comprising said one or more potassium sulfate salts, wherein post-treating comprises:

[0113] (i) washing the solid stream with water, acid, base, or any combination of the foregoing, wherein the solid stream is optionally formulated as a solid, a slurry, or a solution during post-treatment; (ii) acidifying the solid stream, optionally by addition of sulfuric acid, to a pH of about 1-7, 3-6, or 5-6, or about 1-7, 1-6.5, 1-6, 2-6, 3-6, 4-6, 5-6, 2-5, or 3-4, thereby converting residual sodium carbonate and / or sodium bicarbonate impurities into CO2, wherein the solid stream is optionally formulated as a solid, a slurry, or a solution during post-treatment; (iii) converting the solid stream comprising glaserite and / or said additional potassium sodium sulfate salts to potassium sulfate by dissolving the solid stream in w ater and adding potassium chloride at a molar ratio of KCl:K3Na(SO4)2 of about 0.5: 1 to about 2: 1 at about 20-40 °C, optionally at about 20-30 °C. and then separating the resulting potassium sulfate solid by solid-liquid separation, settling, centrifugation, and / or filtration; and / or by crystallizing and separating sodium chloride from the dissolved potassium sulfate; or (iv) any combination of (i)-(iii), thereby producing a product comprising potassium sulfate.

[0114] In certain embodiments the method further comprises, after step (c), post-treating the liquid stream, wherein post-treating comprises: (i) adjusting the liquid stream to a pH of about 9-12, about 8-11, about 8-10, or about 8-9 by addition of alkaline or NaOH, concentrating the liquid stream . settling, filtration, or a combination thereof, thereby producing said carbonic acid salts as a solid or an aqueous solution; (ii) converting sodium carbonate to sodium bicarbonate in the liquid stream by adjusting the liquid stream to pH about 7-9, about 7.5-8.5, or preferably about 8-8.5, separating the formed sodium bicarbonate by a solid-liquid separation process, and optionally recycling the liquid stream comprising unreacted K2CO3, KHCO3, and / or KOH + CO2 and a lower concentration of sodium back into step (a); (iii) converting sodium bicarbonate to sodium carbonate by subjecting the liquid stream or isolated sodium bicarbonate from the liquid stream to heat, thereby producing sodium carbonate, wherein said heat comprises about 80 °C to about 200 °C; or (iv) any combination of (i)-(iii).

[0115] In some embodiments of the method: (i) said heat comprises about 85-190 °C, 90-180 °C, 100-170 °C, 110-160 °C, 120-150 °C, or 130-140 °C and / or (ii) the liquid stream or isolated sodium bicarbonate from the liquid stream is subjected to said heat for about 1 min to about 4 h, about 5 min to about 3 h, about 10 min to about 2.5 h, about 20 min to about 2 h, about 40 min to about 1.5 h, or about 50-60 min.Sodium sulfate byproduct

[0116] In some embodiments, the sodium sulfate byproduct stream can be sourced from any process and / or facility producing a byproduct stream comprising sodium sulfate. In embodiments, the process can comprise a manufacturing process.ATTY DOCKET NO. 1149704.094013

[0117] In certain embodiments of the method, the sodium sulfate byproduct stream comprises a solid, an aqueous solution, and / or an aqueous slurry comprising a sodium sulfate byproduct and / or wastewater derived from:

[0118] (i) any industrial process; (ii) a battery manufacturing process; (iii) a precursor cathode active material (pCAM) production process; (iii) a lithium-ion battery recycling process; and / or (iv) a mining operation, a hydrometal I urgi cal process, a forest industry operation, a logging operation, a wood product manufacturing process, a paper manufacturing process, or a textile manufacturing process.

[0119] In certain embodiments of the method, the sodium sulfate byproduct stream comprises:

[0120] (i) wastewater from a battery manufacturing process; (ii) wastewater from a precursor cathode active material (pCAM) production process; (iii) wastewater from a lithium-ion battery recycling process; and / or (iv) wastewater from a mining operation, a hydrometallurgical process, a forest industry operation, a logging operation, a wood product manufacturing process, a paper manufacturing process, or a textile manufacturing process.

[0121] In certain embodiments of the method, the sodium sulfate byproduct stream comprises byproducts and / or wastewater from a battery manufacturing process and / or byproducts and / or wastewater from a precursor cathode active material (pCAM) production process.

[0122] In certain embodiments of the method, the sodium sulfate byproduct stream comprises:

[0123] (i) one or more transition metal impurities comprising Ni, Mn, and / or Co at a concentration of about 0.0001-50 g / L, about 0.001-45 g / L, 0.01-40 g / L, about 0.1-35 g / L, about 0.5-30 g / L, about 1-25 g / L, about 2-20g / L, about 4-15 g / L, about 6-12 g / L, or about 8- 10 g / L; (ii) one or more heavy metal impurities comprising Cu. Cr, Pb. and / or Zn at concentration of about 0.0001-50 g / L, about 0.001-45 g / L, about 0.01-40 g / L, about 0.1-35 g / L, about 0.5-30 g / L, about 1-25 g / L, about 2-20g / L, about 4-15 g / L, about 6-12 g / L, or about 8-10 g / L; (iii) one or more organic impurities at concentration level of dissolved organic carbon (DOC) of about 1-1000 mg / L, about 5-950 mg / L, about 10-900 mg / L, about 20-850 mg / L, about 30-800 mg / L, about 40-750 mg / L, about 50-700 mg / L, about 60-650 mg / L, about 70-600 mg / L, about 80-550 mg / L, about 90-500 mg / L, about 100-450 mg / L, about 150-400 mg / L, about 200-350 mg / L, or about 250-300 mg / L; or (iv) any combination of (a)-(c).Methods for recycling

[0124] In certain embodiments the method further comprises using and / or recycling the produced potassium sulfate salts, glaserite, potassium sulfate, carbonic acid salts, sodium carbonate and / or sodium bicarbonate, any combination thereof, or any element or ion therefrom back into a process stream related to:

[0125] (i) said battery' manufacturing process; (ii) said precursor cathode active material (pCAM) production process; (iii) said lithium ion battery recycling process; and / or (iv) said mining operation, said hydrometallurgical process, said forest industry operation, saidATTY DOCKET NO. 1149704.094013 logging operation, said wood product manufacturing process, said paper manufacturing process, or a textile (e.g., viscose) manufacturing process.

[0126] In certain embodiments the method further comprises:

[0127] (i) recycling the produced carbonic acid salts for use as an alkaline pretreatment for removal of said metal impurities (e.g., Ca2+, Mg2+, Mn at any oxidation state, Zn at any oxidation state. Co at any oxidation state) from the sodium sulfate byproduct stream or as alkaline reagent for pH adjustment; (ii) recycling the produced glaserite and / or potassium sulfate as seed crystals for formation of the solid stream comprising potassium sulfate salts; (iii) recycling any unreacted carbonation reagent back into step (a); (iv) using the produced potassium sodium sulfate salts, glaserite, and / or potassium sulfate as a fertilizer; (v) recycling the CO2 formed in post-treatment of the solid stream comprising potassium sulfate salts as said carbonation reagent, (vi) production of the carbonation reagents (e g., CO2, potassium bicarbonate, and / or potassium carbonate) by the same plant producing the sodium sulfate byproduct stream; (vii) a cyclical process wherein one or more of said at least one carbonation reactants (e.g., CO2. potassium bicarbonate, and / or potassium carbonate) are originally obtained from the sodium sulfate byproduct stream; (viii) a cyclical process wherein the produced sodium bicarbonate and / or sodium carbonate is recycled back into said process stream related to said pCAM production process for use as (i) a base for pCAM precipitation or pCAM recycling; and / or (ii) as a pH adjustment chemical for water and / or wastewater treatment; (ix) recycling part or all of CO2 isolated from the solid stream and / or the liquid stream for use as a recycled carbonation reagent; (x) recycling the potassium in the solid stream for use as said carbonation reagent by a (1) dissolving or suspending the produced potassium sulfate salts in water or an aqueous solution comprising Ca(OH)2(aq), optionally at temperature of 30-80 °C. 35-80 °C, 40-80 °C, 45-80 °C. 50-80 °C, 55-80 °C, preferably at 60-80 °C and optionally at a pH of 7-11, 7.5-10.5, 8-10, 8.5-10, or preferably 8- 10; (2) reacting the dissolved or suspended potassium sulfate salts with lime (CaO and / or Ca(OH)2(aq)) to form a calcium sulfate and / or calcium carbonate precipitate and a potassium hydroxide solution; (3) separating the potassium hydroxide solution from the calcium sulfate precipitate, such as by and solid-liquid (S / L) separation process; (4) reacting the potassium hydroxide solution with CO2 or H2CO3 to form K2CO3; and (5) recycling the formed K2CO3 for use as said carbonation reagent; or (xi) any combination of (i)-(x).

[0128] In some embodiments, the calcium carbonate precipitate forms as a precipitation product arising from carbonate impurities in the solid stream comprising said potassium sulfate salts.

[0129] In some embodiments of the method, the step of recycling the potassium in the solid stream for use as said carbonation reagent can be exemplified by the following equations for recycling potassium from formed potassium carbonate (K2SO4 (s)):K2SO4 (s or aq) + Ca(OH)2 (aq) + XH2O —> 2K0H (aq) + CaSO4 XH2O (s) where (x=0, 1, 2, 3, etc.) 2K0H + CO2 K2CO3 + H2OATTY DOCKET NO. 1149704.094013

[0130] In some embodiments of the method, the step of recycling the potassium in the solid stream for use as said carbonation reagent can be exemplified by the following equations for recycling potassium from formed glaserite (K3Na(SC>4)2 (s)):KsNa(SO4)2 (s or aq) + 2Ca(OH)2 (aq) + XH2O — 3K0H (aq) + NaOH (aq) + 2CaSO4xH20 (s) where (x=0, 1, 2, 3, etc.)2 KOH (aq) + CO2 K2CO3 (aq) + H2O

[0131] In certain embodiments of the method, the reaction mixture comprises a molar ratio of K:Na of>l: l, about 1.05: 1 to about 2: 1. about 1.1: 1 to about 2: 1. about 1.2: 1 to about 1.8: 1. or about 1.4: 1 to about 1.6: 1 and wherein the method further comprises:

[0132] (i) recycling any unreacted carbonation reagent back into step (a); and / or (ii) separating the liquid stream comprising said carbonic acid salts and said unreacted carbonation reagent and recycling all or part of the liquid stream back into step (a).

[0133] In certain embodiments of the method:

[0134] (i) said produced sodium bicarbonate and / or sodium carbonate comprises a purity in the range of about 50-100%, about 60-95 wt%, about 70-95%, about 80-95%, or about 90- 95%; and / or (ii) the produced potassium sulfate comprises a purity in the range of about 50- 100%, about 60-100%, about 70-99 wt%, about 80-99%, about 90-99%, or about 95-99%.

[0135] In another aspect, the present invention provides a composition comprising:

[0136] (i) sodium bicarbonate and / or sodium carbonate produced by any of the foregoing methods; (ii) potassium sulfate produced by any of the foregoing methods; and / or (iii) glaserite produced by any of the foregoing methods.METHODSNon-Limiting, exemplary NaiSCL treatment process by carbonate conversion with potassium bicarbonate / potassium carbonate:

[0137] 1) Na2SO4 (aq) stream is optionally concentrated from < 10 wt-% concentration to > 20 wt-% in an evaporator.

[0138] 2) Na2SO4 (aq) is reacted with potassium bicarbonate and / or potassium carbonate at pH > 7. The reaction pH range is favorably adjusted to pH > 9 for reacting with potassium carbonate. The reaction temperature is favorably 20-60 °C, 20-40 °C, or more favorably 20- 30 °C.

[0139] 3) The formed first product with lower solubility (glaserite and / or K2SO4) is separated from the liquid stream by solid-liquid (S / L) separation process.

[0140] 4) The first product glaserite and / or K2SO4 is optionally purified with rinsing, filtration and / or pH adjustment, and used as fertilizer.

[0141] 5) The Na2COs in the liquid stream is optionally concentrated using evaporator.ATTY DOCKET NO. 1149704.094013

[0142] 6) The NazCOs in the liquid stream can be optionally purified with filtration, ion exchange, precipitation and / or sorption methods and the purified product is recycled back to the process and used e.g., as pH adjustment chemical, or sold elsewhere.Non-Limiting, exemplary NazSCL treatment process by carbonate conversion with CO2 and a potassium salt:

[0143] 1) Na2SC>4 (aq) stream is optionally concentrated from < 10 wt-% to > 20 wt-%.

[0144] 2) Na2SO4 is reacted with carbon dioxide and potassium containing salt, favorably potassium hydroxide.

[0145] The reaction pH range is adjusted to pH > 7, favorably to pH > 9.

[0146] The reaction temperature is favorably 20-60 °C 20-40 °C, more favorably 20-30 °C at pressure higher than 1 bar.

[0147] 3) The formed first product with lower solubility' (glaserite and / or K2SO4) is separated from the liquid stream by S / L separation process

[0148] 4) The first solid product (glaserite and / or K2SO4) is optionally purified with rinsing, filtration and / or pH adjustment and used as fertilizer.

[0149] 5) The Na2COs in the liquid stream is optionally concentrated with an evaporator

[0150] 6) The Na2CO3 in the liquid stream is optionally purified with filtration, ion exchange, precipitation and / or sorption methods and the product is recycled back to the process and used e.g., as pH adjustment chemical, or sold elsewhere.

[0151] The methods and compositions illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein and / or any element specifically disclosed herein. Exemplary embodiments of the invention and its advantages are further disclosed in the following examples.EXAMPLES

[0152] The examples provided herein are for illustrative purposes so that the invention may be more fully understood. These examples should not be construed as limiting the invention in any way.

[0153] The examples provided herein describe methods of the present invention for treating sodium sulfate byproduct with one or more carbonation reagents (e.g., (i) potassium bicarbonate and / or potassium carbonate; or (ii) carbon dioxide (CO2) and potassium hydroxide (KOH)) to obtain potassium sulfate salts (e.g., glaserite (K3Na(SO4)2), potassium sulfate (K2SO4), and / or sodium potassium sulfate salts) and carbonic acid salts (e.g., sodium bicarbonate and / or sodium carbonate) as products. During the process, glaserite is either isolated as a product or converted to potassium sulfate. The reaction products were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), ion chromatography (IC), and inductively coupled mass plasma spectrometry (ICP-MS).ATTY DOCKET NO. 1149704.094013Example 1: Treatment of a sodium sulfate solution with potassium carbonate

[0154] A sodium sulfate solution (20 wt% in water) was treated with potassium carbonate (K2CO3) using carbonation reaction conditions 1-6 according to Table 1 to produce Samples 1S-6S and 1L-6L. For conditions 1-6, sufficient potassium carbonate (K2CO3) was added to form molar ratios of K2COs:Na2SO4 of 1: 1 or 1.5: 1. Reaction temperatures were maintained at 30 °C or 40 °C. Reaction times were varied between 15 min and 180 min. Reaction mixtures were adjusted a pH of 11.8-12.2 or 9.8-10.2 by addition of 10 wt-% NaOH(aq).

[0155] During each reaction, a precipitate was formed. After reaction times elapsed, the formed precipitates were filtered using a 0.45 pm filter to produce a solid (i.e., solid stream, Samples 1S-6S) and a supernatant (liquid stream, Samples 1L-6L).

[0156] Solids were dried at 50 °C overnight and then characterized qualitatively and semi- quantitatively with XRD and XRF. From this data, the salt composition of the solid phase was determined an K / Na and K / S ratios were calculated from XRF results of weight fractions of elements in the sample; e.g., in K2CO3-IS, the K and S weight fractions were 28 wt-% and 14 wt-% and the K / S ratio was 28 / 14 = 2.

[0157] Concentrations of Na, K, and SO4 (wt%) of the liquid phase were determined by ICP- MS and IC. From these results, the wt% removal of SO4 from the original sodium sulfate solution was calculated. The SO4 fraction in the original feed samples was 13.5 wt-% (20 wt-% as sodium sulfate, 20*(32.07+4* 16) / (22.99*2+32.07+4* 16) = 13.5 wt-%. From IC, it was calculated that the liquid fraction contains 4.5 wt-% of sulfate; e.g., 100%- 4.5 / 13.5*100% = 66.7% sulfate in the solid.

[0158] Results are shown in Table 1.Example 2: Treatment of a sodium sulfate solution with potassium carbonate

[0159] Reactions were performed according to Example 1, using carbonation reaction conditions 7-10 according to Table 1 to produce Samples 7S-10S and 7L-10L, with the exception that the supernatant was left to stand in settlement tank for 24 h at room temperature (25 °C) to form a second precipitate. After settling, the mixtures were filtered a second time. The isolated solid stream was either combined with the precipitate formed from the first filtration step, or treated separately as a second solid stream (e.g., disposed, or processed further).

[0160] Isolated solids w ere dried at 50 °C overnight and then characterized qualitatively and semi-quantitatively with XRD and XRF. From this data, the salt composition of the solid phase was determined an K / Na and K / S ratios were calculated according to Example 1.

[0161] Concentrations of Na, K, and SO4 (wt%) of the liquid phase were determined by ICP- MS and IC. From these results, the wt% removal of SO4 from the original sodium sulfate solution was calculated according to Example 1.

[0162] Results are shown in Table 1.ATTY DOCKET NO. 1149704.094013Results

[0163] These results indicate that the inventive carbonation method for treating sodium sulfate byproduct with one or more carbonation reagents (e.g., K2CO3) effectively produced glaserite (KsNa(SO4)2) as a precipitate in good yields (29 g to 59 g of dried solid). % Yields ranged from 64-75% considering only tests with K / Na ratio of 1 : 1 in the feed. For excess K (1.5: 1 K:Na), higher yields of solid were achieved. Glaserite was isolated as either a pure product or as a mixture containing 4 wt% HNa3(CO3)2(H2O)2.

[0164] These results provide initial proof of concept that the inventive methods for treating sodium sulfate byproduct can be performed a pH >9 (e.g., 10-12) and at 30-40 °C to obtain adequate solid yields in as little as 15 min.ATTY DOCKET NO. 1149704.094013Table 1: Carbonation reaction conditions 1-10 and results from characterization of solid streams (1S-10S) and liquid streams (1L-10L).§ Small amount of unidentified compounds; * K / Na and K / S in glaserite: 5.1 and 1.8, respectively; ** SO4 content in yield (20 wt-% Na2S04) 13.53% - removal from feed calculated from the residual SO4 concentration in the liquid phase after treatment;55% Compositions are approximate values (±10 %)

Claims

ATTY DOCKET NO. 1149704.094013CLAIMSWhat is claimed is:

1. A method of producing (i) one or more potassium sulfate salts and (ii) one or more carbonic acid salts from a sodium sulfate byproduct stream, the method comprising:(a) contacting the sodium sulfate byproduct stream with at least one carbonation reagent, thereby producing a solid stream comprising said potassium sulfate salts and a liquid stream comprising said carbonic acid salts, wherein the carbonation reagent comprises(i) potassium bicarbonate and / or potassium carbonate; or(ii) carbon dioxide (CO2) and a potassium salt;(b) isolating the solid stream comprising potassium sulfate salts; and(c) isolating the liquid stream comprising said carbonic acid salts.

2. The method of claim 1, wherein:(i) step (b) of claim 1 comprises isolating the solid stream from the liquid stream by solid-liquid separation to form an isolated solid;(ii) the solid stream comprises said potassium sulfate salts and optionally a residual amount of said carbonic acid salts;(iii) the liquid stream comprises said carbonic acid salts and optionally a residual amount of said potassium sulfate salts;(iv) said potassium sulfate salts comprise potassium sulfate (K2SO4); glaserite (K3Na(SO4h); a mixture of potassium sulfate and glaserite; one or more additional potassium sodium sulfate salts of the form KnNam(SO4)2, wherein n and m are between 1 and 3; one or more additional potassium sodium sulfate salts of the form KxNay(SO4)4, wherein x and y are between 1 and 7; aphthitalite; or any combination of the foregoing;(v) said carbonic acid salts comprise sodium carbonate, sodium bicarbonate, or a mixture thereof;(vi) when step (a) of claim 1 is performed at a pH ranging from 7-9, the primary carbonic acid salt comprises sodium bicarbonate;(vii) when step (a) of claim 1 is performed at a pH ranging from 9-12, the primary carbonic acid salt comprises sodium carbonate; or(viii) any combination of (i)-(vii).

3. The method of claim 1 or 2, wherein the carbonation reagent:(i) is formed separately or in situ with the sodium sulfate byproduct stream;(ii) is formed prior to step (a) of claim 1 or during step (a) of claim 1;ATTY DOCKET NO. 1149704.094013(iii) is formed in a scrubber, a pipe reactor, or in any suitable vessel or process equipment related to the sodium sulfate byproduct stream; or(iv) comprises said potassium bicarbonate and / or potassium carbonate;(v) comprises said potassium bicarbonate and / or potassium carbonate, wherein the potassium bicarbonate and / or potassium carbonate is produced by reacting carbon dioxide (CO2) with potassium hydroxide(KOH), potassium oxide (K2O), or a mixture thereof;(vi) comprises said CChand said potassium salt;(vii) comprises said CChand said potassium salt, wherein said potassium salt comprises potassium hydroxide (KOH), potassium oxide (K2O), or a mixture thereof;(viii) comprises said CO2 and said potassium salt, wherein the CChis maintained at a pressure of 1-5 bar; or(ix) any combination of (i)-(viii).

4. The method of any one of the foregoing claims, further comprising:(i) prior to step (a) of claim 1, dissolving a solid sodium sulfate byproduct to form the sodium sulfate byproduct stream or providing the sodium sulfate byproduct stream as an aqueous solution and / or slurry;(ii) prior to step (a) of claim 1, adjusting the sodium sulfate byproduct stream and / or the carbonation reagents to a pH ranging from 7-12;(iii) during step (a) of claim 1, agitating or mixing the sodium sulfate byproduct stream with the at least one carbonation reagent;(iv) during step (a), (b), and / or (c) of claim 1, maintaining a temperature of 20- 60 °C;(v) during step (a) of claim 1, optionally adding a seed crystal of glaserite and / or potassium sulfate;(vi) during step (a) of claim 1, contacting the sodium sulfate byproduct stream with the carbonation reagents at a pH ranging from 7-12;(vii) during step (a) of claim 1, adjusting the pH to 9-12; or(viii) any combination of (i)-(vii), wherein the pH is optionally adjusted by addition of an alkaline reagent, sodium carbonate, sodium bicarbonate, NaOH, KOH, or K2O.

5. The method of any one of the foregoing claims, wherein:(i) the reaction mixture comprises a molar ratio of K:Na of 0.5:1 to 2:1; and / or(ii) the reaction mixture comprises a molar ratio of K:SO4 of 1:1 to 4:1.ATTY DOCKET NO. 1149704.0940136. The method of any one of the foregoing claims, further comprising prior to step (a) of claim 1 pretreating the sodium sulfate byproduct stream to remove one or more impurities comprising one or more solid impurities, transition metal hydroxides, transition metals, heavy metals, organic impurities, polymeric impurities, or any combination thereof from the sodium sulfate byproduct stream, wherein pretreating comprises:(i) concentrating the sodium sulfate byproduct stream;(ii) settling, screening, and / or filtering the solid impurities from the byproduct stream;(iii) adjusting the pH of the byproduct stream to a pH of about 6 to about 8, thereby precipitating impurities that precipitate at a pH of about 6 to about 8, and removing the impurities by solid liquid separation;(iv) adjusting the pH of byproduct stream further to about 8 to about 10, thereby precipitating impurities that precipitate at a pH from about 8 to about 10, and removing the impurities by solid liquid separation;(v) allowing metals to precipitate and / or settle as one or more low soluble salts, hydroxides and / or carbonates, and removing the impurities by solid liquid separation;(vi) treating the byproduct stream with one or more ion exchange methods;(vii) treating the byproduct stream with an adsorption media or activated carbon; or(viii) any combination of (i)-(vii), wherein any or all of (i)-(viii) are performed in any order prior to contacting the sodium sulfate byproduct stream with said at least one carbonation reagent according to step (a) of claim 1.

7. The method of any one of the foregoing claims, wherein after step (c) of claim 1 the method further comprises post-treating the solid stream comprising said one or more potassium sulfate salts, wherein post-treating comprises:(i) washing the solid stream with water, acid, base, or any combination of the foregoing, wherein the solid stream is optionally formulated as a solid, a slurry, or a solution during post-treatment;(ii) acidifying the solid stream, optionally by addition of sulfuric acid, to a pH of 1-7, 1-6, 3-6, 5-6, 2-5, or 3-4, thereby converting residual sodium carbonate and / or sodium bicarbonate impurities into CO2, wherein the solid stream is optionally formulated as a solid, a slurry, or a solution during posttreatment;(iii) converting the solid stream comprising glaserite and / or said additional potassium sodium sulfate salts to potassium sulfate by dissolving the solidATTY DOCKET NO. 1149704.094013 stream in water and adding potassium chloride at a molar ratio of KCI:K3Na(SO4)2of 0.5:1 to 2:1 at 20-40 °C, optionally at 20-30 °C, and then separating the resulting potassium sulfate solid by solid-liquid separation, settling, centrifugation, and / or filtration; and / or by crystallizing and separating sodium chloride from the dissolved potassium sulfate; or(iv) any combination of (i)-(iii), thereby producing a product comprising potassium sulfate.

8. The method of any one of the foregoing claims, wherein after step (c) of claim 1 the method further comprises post-treating the liquid stream, wherein post-treating comprises:(i) adjusting the liquid stream to a pH of 9-12, 8-11, 8-10, or 8-9 by addition of alkaline or NaOH, concentrating the liquid stream , settling, filtration, or a combination thereof, thereby producing said carbonic acid salts as a solid or an aqueous solution;(ii) converting sodium carbonate to sodium bicarbonate in the liquid stream by adjusting the liquid stream to pH 7-9, 7.5-8.5, or preferably 8-8.5, separating the formed sodium bicarbonate by a solid-liquid separation process, and optionally recycling the liquid stream comprising unreacted K2CO3, KHCO3, and / or KOH + CO2and a lower concentration of sodium back into step (a) of claim 1;(iii) converting sodium bicarbonate to sodium carbonate by subjecting the liquid stream or isolated sodium bicarbonate from the liquid stream to heat, thereby producing sodium carbonate, wherein said heat comprises about 80 °C to about 200 °C; or(iv) any combination of (i)-(iii).

9. The method of any one of the foregoing claims, wherein the sodium sulfate byproduct stream comprises a solid, an aqueous solution, and / or an aqueous slurry comprising a sodium sulfate byproduct derived from:(i) any industrial process;(ii) a battery manufacturing process;(iii) a precursor cathode active material (pCAM) production process;(iv) a lithium-ion battery recycling process; and / or(v) a mining operation, a hydrometallurgical process, a forest industry operation, a logging operation, a wood product manufacturing process, a paper manufacturing process, or a textile manufacturing process.

10. The method of any one of the foregoing claims, wherein the sodium sulfate byproduct stream comprises:(i) one or more transition metal impurities comprising Ni, Mn, and / or Co at aATTY DOCKET NO. 1149704.094013 concentration of 0.0001-50 g / L;(ii) one or more heavy metal impurities comprising Cu, Cr, Pb, and / or Zn at concentration of 0.0001-50 g / L;(iii) one or more organic impurities at concentration level of dissolved organic carbon (DOC) of 1-1000 mg / L; or(iv) any combination of (i)-(iii).

11. The method of any one of the foregoing claims, further comprising using and / or recycling the produced potassium sulfate salts, glaserite, potassium sulfate, carbonic acid salts, sodium carbonate and / or sodium bicarbonate, any combination thereof, or any element or ion therefrom into a process stream related to:(i) said battery manufacturing process;(ii) said precursor cathode active material (pCAM) production process;(iii) said lithium ion battery recycling process; and / or(iv) said mining operation, said hydrometallurgical process, said forest industry operation, said logging operation, said wood product manufacturing process, said paper manufacturing process, or a textile (e.g., viscose) manufacturing process.

12. The method of any one of the foregoing claims, further comprising:(i) recycling the produced carbonic acid salts for use as an alkaline pretreatment for removal of said metal impurities (e.g., Ca2+, Mg2+, Mn, and Zn) from the sodium sulfate byproduct stream or as alkaline reagent for pH adjustment;(ii) recycling the produced glaserite and / or potassium sulfate as seed crystals for formation of the solid stream comprising potassium sulfate salts;(iii) recycling any unreacted carbonation reagent back into step (a) of claim 1;(iv) using the produced potassium sodium sulfate salts, glaserite, and / or potassium sulfate as a fertilizer;(v) optionally recycling the CO2 formed in post-treatment of the solid stream comprising potassium sulfate salts as said carbonation reagent;(vi) production of the carbonation reagents (e.g., CO2, potassium bicarbonate, and / or potassium carbonate) by the same plant producing the sodium sulfate byproduct stream of claim 1;(vii) a cyclical process wherein one or more of said at least one carbonation reactants (e.g., CO2, potassium bicarbonate, and / or potassium carbonate) are originally obtained from the sodium sulfate byproduct stream;(viii) a cyclical process wherein the produced sodium bicarbonate and / or sodium carbonate is recycled back into said process stream related to said pCAMATTY DOCKET NO. 1149704.094013 production process for use as (i) a base for pCAM precipitation or pCAM recycling; and / or (ii) as a pH adjustment chemical for water and / or wastewater treatment;(ix) recycling part or all of CO2 isolated from the solid stream and / or the liquid stream for use as a recycled carbonation reagent;(x) recycling the potassium in the solid stream for use as said carbonation reagent by (1) dissolving or suspending the produced potassium sulfate salts in water or an aqueous solution comprising Ca(OH)2<aq), optionally at temperature of 30-80 °C, more preferably at 60-80 °C and optionally at a pH of 7-11 or 9-10; (2) reacting the dissolved or suspended potassium sulfate salts with lime (CaO and / or Ca(OH)2(aq )) to form a calcium sulfate and / or calcium carbonate precipitate and a potassium hydroxide solution; (3) separating the potassium hydroxide solution from the calcium sulfate precipitate; (4) reacting the potassium hydroxide solution with CO2 or H2CO3 to form K2CO3; and (5) recycling the formed K^CChfor use as said carbonation reagent; or(xi) any combination of (i)-(x).

13. The method of any one of the foregoing claims, wherein the reaction mixture comprises a molar ratio of K:Na of >1:1 and wherein the method further comprises:(i) recycling any unreacted carbonation reagent back into step (a) of claim 1; and / or(ii) separating the liquid stream comprising said carbonic acid salts and said unreacted carbonation reagent and recycling all or part of the liquid stream back into step (a) of claim 1.

14. The method of any one of the foregoing claims, wherein:(i) said produced sodium bicarbonate and / or sodium carbonate comprises a purity in the range of 50-100% or 60-95 wt%; and / or(ii) the produced potassium sulfate comprises a purity in the range of 50-100% or 70-99 wt%.

15. A composition comprising:(i) sodium bicarbonate and / or sodium carbonate produced by a method of any one of the foregoing claims;(ii) potassium sulfate produced by a method of any one of the foregoing claims; and / or(iii) glaserite produced by a method of any one the foregoing claims.

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