PROCESSING HARD ROCK LITHIUM MINERALS OR OTHER MATERIALS TO PRODUCE LITHIUM MATERIALS AND BYPRODUCTS CONVERTED FROM A SODIUM SULFATE INTERMEDIATE PRODUCT

Abstract

Methods are provided for processing a lithium-containing material (e.g., a mineral like spodumene) whereby a lithium sulfate solution derived from the material is reacted with a primary reagent (e.g., Na.sub.2CO.sub.3 or NaOH) to produce a mixed solution of primary lithium product (e.g., Li.sub.2CO.sub.3 or LiOH) and Na.sub.2SO.sub.4. In addition to primary lithium product, a separated Na.sub.2SO.sub.4 solution is produced and converted to a byproduct (e.g., CaSO.sub.4, NaNO.sub.3, NaOH, H.sub.2SO.sub.4) by reaction with a salt chemical (e.g., Ca(NO.sub.3).sub.2) or alkali chemical (e.g., Ca(OH).sub.2), or by electrolysis or electrodialysis. Byproducts are re-used to reduce reagent inputs. Residual lithium in an output solution is reacted with a secondary reagent (e.g., CO.sub.2 from flue gas, or H.sub.3PO.sub.4) to produce secondary lithium products (e.g., Li.sub.2CO.sub.3 or Li.sub.3PO.sub.4), which may be re-used to reduce reagent inputs and increase lithium recovery.

Claims

1. A method of processing an aqueous feed solution comprising lithium sulfate to produce a primary lithium product and a byproduct, the method comprising the steps of: (a) reacting the aqueous feed solution with a primary reagent to produce a mixed solution comprising the primary lithium product and sodium sulfate, wherein either: (i) the primary reagent comprises sodium carbonate and the primary lithium product comprises lithium carbonate; or (ii) the primary reagent comprises sodium hydroxide and the primary lithium product comprises lithium hydroxide; (b) separating the primary lithium product from the mixed solution, and producing a separated sodium sulfate solution from the mixed solution, wherein: (i) if the primary lithium product comprises lithium carbonate, then: (A) separating the primary lithium product from the mixed solution comprises crystallizing the lithium carbonate from the mixed solution; and (B) the separated sodium sulfate solution comprises a solution remaining after step (b)(i)(A); or (ii) if the primary lithium product comprises lithium hydroxide, then: (A) producing the separated sodium sulfate solution from the mixed solution comprises separating decahydrate of sodium sulfate from the mixed solution, and dissolving the separated decahydrate of sodium sulfate in water; and (B) separating the primary lithium product from the mixed solution comprises crystallizing the lithium hydroxide from a solution remaining after step (b)(ii)(A); and (c) performing a conversion process on the separated sodium sulfate solution to produce to produce sodium hydroxide and sulfuric acid, the conversion process comprising removing multivalent ion impurities from the separated sodium sulfate solution and: (i) providing the separated sodium sulfate solution to a three-compartment electrolysis cell comprising at least an anion exchange membrane and a cation exchange membrane and configured to operate below 70 C.; or (ii) providing the separated sodium sulfate solution to a three-compartment electrodialysis cell comprising at least an anion exchange membrane, a cation exchange membrane and a bi-polar membrane and configured to operate below 50 C.; and (d) recovering an output stream comprising the sodium hydroxide and an output stream comprising the sulfuric acid, wherein the output streams are substantially free of sodium sulfate.

2. The method of claim 1, further comprising, before step (a), preparing the aqueous feed solution by reacting a lithium-containing material with sulfuric acid.

3. The method of claim 2, wherein the lithium-containing material comprises a mineral.

4. The method of claim 3, wherein before step (a), the method comprises a step of subjecting the mineral to a calcination process for phase conversion of the mineral.

5. The method of claim 3, wherein the mineral comprises spodumene.

6. The method of claim 3 wherein the mineral comprises petalite, lepidolite, zinnwaldite, amblygonite, eucryptite, hectorite, a lithium clay, or jadarite.

7. The method of claim 2, wherein the lithium-containing material comprises lithium carbonate.

8. The method of claim 2, wherein the lithium-containing material comprises material from a used battery.

9. The method of claim 1, wherein the primary reagent comprises sodium carbonate and the primary lithium product comprises lithium carbonate.

10. The method of claim 1, wherein the primary reagent comprises sodium hydroxide and the primary lithium product comprises lithium hydroxide.

11. A method of processing an aqueous feed solution comprising lithium sulfate to produce a primary lithium product and a byproduct, the method comprising the steps of: (a) reacting the aqueous feed solution with a primary reagent to produce a mixed solution comprising the primary lithium product and sodium sulfate, wherein either: (i) the primary reagent comprises sodium carbonate and the primary lithium product comprises lithium carbonate; or (ii) the primary reagent comprises sodium hydroxide and the primary lithium product comprises lithium hydroxide; (b) separating the primary lithium product from the mixed solution, and producing a separated sodium sulfate solution from the mixed solution, wherein: (i) if the primary lithium product comprises lithium carbonate, then: (A) separating the primary lithium product from the mixed solution comprises crystallizing the lithium carbonate from the mixed solution; and (B) the separated sodium sulfate solution comprises a solution remaining after step (b)(i)(A); or (ii) if the primary lithium product comprises lithium hydroxide, then: (A) producing the separated sodium sulfate solution from the mixed solution comprises separating decahydrate of sodium sulfate from the mixed solution, and dissolving the separated decahydrate of sodium sulfate in water; and (B) separating the primary lithium product from the mixed solution comprises crystallizing the lithium hydroxide from a solution remaining after step (b)(ii)(A); and (c) performing a conversion process on the separated sodium sulfate solution to produce the byproduct, the conversion process comprising: reacting the separated sodium sulfate solution with a salt chemical, wherein: the salt chemical comprises calcium nitrate, and the byproduct comprises calcium sulfate and sodium nitrate; the salt chemical comprises barium chloride and the byproduct comprises barium sulfate and sodium chloride; the salt chemical comprises calcium chloride and the byproduct comprises calcium sulfate and sodium chloride; the salt chemical comprises copper nitrate and the byproduct comprises copper sulfate and sodium nitrate; the salt chemical comprises nickel chloride and the byproduct comprises nickel sulfate and sodium chloride; the salt chemical comprises nickel nitrate and the byproduct comprises nickel sulfate and sodium nitrate; or the salt chemical comprises potassium carbonate, and the byproduct comprises potassium sulfate and sodium carbonate; and (d) recovering residual lithium, wherein a solution resulting from step (c) comprises lithium ions, the recovering comprising providing, to the solution resulting from step (c), a secondary reagent comprising phosphoric acid, thereby reacting the lithium ions to produce a secondary lithium product comprising lithium phosphate.

12. The method of claim 11, further comprising, before step (a), preparing the aqueous feed solution by reacting a lithium-containing material with sulfuric acid.

13. The method of claim 12, wherein the lithium-containing material comprises spodumene.

14. The method of claim 12, wherein the lithium-containing material comprises petalite, lepidolite, zinnwaldite, amblygonite, eucryptite, hectorite, a lithium clay, or jadarite.

15. The method of claim 12, wherein the lithium-containing material comprises material from a used battery.

16. A method of processing an aqueous feed solution comprising lithium sulfate to produce a primary lithium product and a byproduct, the method comprising the steps of: (a) reacting the aqueous feed solution with a primary reagent to produce a mixed solution comprising the primary lithium product and sodium sulfate, wherein either: (i) the primary reagent comprises sodium carbonate and the primary lithium product comprises lithium carbonate; or (ii) the primary reagent comprises sodium hydroxide and the primary lithium product comprises lithium hydroxide; (b) separating the primary lithium product from the mixed solution, and producing a separated sodium sulfate solution from the mixed solution, wherein: (i) if the primary lithium product comprises lithium carbonate, then: (A) separating the primary lithium product from the mixed solution comprises crystallizing the lithium carbonate from the mixed solution; and (B) the separated sodium sulfate solution comprises a solution remaining after step (b)(i)(A); or (ii) if the primary lithium product comprises lithium hydroxide, then: (A) producing the separated sodium sulfate solution from the mixed solution comprises separating decahydrate of sodium sulfate from the mixed solution, and dissolving the separated decahydrate of sodium sulfate in water; and (B) separating the primary lithium product from the mixed solution comprises crystallizing the lithium hydroxide from a solution remaining after step (b)(ii)(A); and (c) performing a conversion process on the separated sodium sulfate solution to produce the byproduct, the conversion process comprising reacting the separated sodium sulfate solution with an alkali chemical, wherein: the alkali chemical comprises calcium hydroxide, and the byproduct comprises calcium sulfate and sodium hydroxide; the alkali chemical comprises ammonium hydroxide, and the byproduct comprises ammonium sulfate and sodium hydroxide; the alkali chemical comprises barium hydroxide, and the byproduct comprises barium sulfate and sodium hydroxide; or the alkali chemical comprises potassium hydroxide, and the byproduct comprises potassium sulfate and sodium hydroxide; and (d) recovering residual lithium, wherein a solution resulting from step (c) comprises lithium ions, the recovering comprising providing, to the solution resulting from step (c), a secondary reagent comprising phosphoric acid, thereby reacting the lithium ions to produce a secondary lithium product comprising lithium phosphate.

17. The method of claim 16, further comprising, before step (a), preparing the aqueous feed solution by reacting a lithium-containing material with sulfuric acid.

18. The method of claim 17, wherein the lithium-containing material comprises spodumene.

19. The method of claim 17, wherein the lithium-containing material comprises petalite, lepidolite, zinnwaldite, amblygonite, eucryptite, hectorite, a lithium clay, or jadarite.

20. The method of claim 17, wherein the lithium-containing material comprises material from a used battery.

21-53. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the drawings, like elements may be assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention.

[0025] Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

[0026] FIG. 1 is a flow chart of a method for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 lithium product, and Na.sub.2SO.sub.4 byproduct known in the prior art.

[0027] FIG. 2 is a flow chart of a method for processing -spodumene concentrate to produce a LiOHH.sub.2O lithium product, and Na.sub.2SO.sub.4 byproduct, known in the prior art.

[0028] FIG. 3 is a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 primary lithium product, CaSO.sub.4 and NaNO.sub.3 byproducts by reaction of a Na.sub.2SO.sub.4 intermediate product with a salt chemical, and Li.sub.3PO.sub.4 secondary lithium products.

[0029] FIG. 4 is a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a LiOHH.sub.2O primary lithium product, CaSO.sub.4 and NaNO.sub.3 byproducts by reaction of a Na.sub.2SO.sub.4 intermediate product with a salt chemical, and optionally Li.sub.3PO.sub.4 secondary lithium products.

[0030] FIG. 5 is a flow chart for an embodiment of a method of the invention for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 primary lithium product, CaSO.sub.4 and NaOH byproducts by reaction of a Na.sub.2SO.sub.4 intermediate product with an alkali chemical, and optionally Li.sub.2CO.sub.3 or Li.sub.3PO.sub.4 secondary lithium products.

[0031] FIG. 6 is a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a LiOHH.sub.2O primary lithium product, CaSO.sub.4 and NaOH byproducts by the reaction of a Na.sub.2SO.sub.4 intermediate product with an alkali chemical, and optionally Li.sub.2CO.sub.3 or Li.sub.3PO.sub.4 secondary lithium products.

[0032] FIG. 7 is a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 primary lithium product, and NaOH and H.sub.2SO.sub.4 byproducts by electrolysis or electrodialysis of a Na.sub.2SO.sub.4 intermediate product.

[0033] FIG. 8 is a schematic diagram illustrating Na.sub.2SO.sub.4 conversion to NaOH and H.sub.2SO.sub.4 with an embodiment of an electrolysis process that may be used according to the method illustrated in FIG. 7 or FIG. 10.

[0034] FIG. 9 is a schematic diagram illustrating Na.sub.2SO.sub.4 conversion to NaOH and H.sub.2SO.sub.4 with an embodiment of a bipolar membrane electrodialysis (BMED) method that may be used according to the method illustrated in FIG. 7 or FIG. 10.

[0035] FIG. 10 is a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a LiOHH.sub.2O primary lithium product, NaOH and H.sub.2SO.sub.4 byproducts by electrolysis or electrodialysis of a Na.sub.2SO.sub.4 intermediate product.

DETAILED DESCRIPTION OF EMBODIMENTS

Overview

[0036] Example methods and systems are described herein. It should be understood that the words example and exemplary are used herein to mean serving as an example, instance, or illustration. Any embodiment or feature described herein as being an example or exemplary is not necessarily to be construed as preferred or advantageous over other embodiments or features. The example embodiments described herein are not meant to be limiting. It will be readily understood that certain aspects of the disclosed systems and methods can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0037] The present disclosure relates to processing a material containing lithium, such as hard rock comprising lithium to produce either lithium carbonate (Li.sub.2CO.sub.3) or lithium hydroxide monohydrate (LiOHH.sub.2O), or both of them. Any term or expression not expressly defined herein shall have its commonly accepted definition understood by a person skilled in the art.

[0038] In a broad aspect, in embodiments, the present disclosure provides a method of processing a material containing lithium, such as hard rock lithium minerals like -spodumene to produce a primary lithium product comprising either lithium carbonate (Li.sub.2CO.sub.3) or lithium hydroxide monohydrate (LiOHH.sub.2O), and a byproduct by conversion of a sodium sulfate (Na.sub.2SO.sub.4) intermediate product. In general, the method comprises the steps of: (a) preparing an aqueous feed solution comprising lithium sulfate by reacting the lithium-containing material with sulfuric acid; (b) reacting the feed solution with a primary reagent to produce a mixed solution of the primary lithium product and a sodium sulfate solution; (c) separating the primary lithium product from the mixed solution, and producing a separated sodium sulfate solution (e.g., either as a result of separating the primary lithium product from the mixed solution by precipitation, or by separating decahydrate of sodium sulfate from the mixed solution and dissolving the separated decahydrate of sodium sulfate in water); and (d) performing a conversion process on the separated sodium sulfate solution to produce the byproduct.

EXAMPLES

[0039] The following examples provide embodiments of the methods of the present disclosure, as applied to processing -spodumene concentrate. The following example are not limitative in nature.

[0040] In the following examples, a feed solution of aqueous solution comprising Li.sub.2SO.sub.4 may be produced by leaching of material produced by acid-roasting of -spodumene, which is produced by calcination of -spodumene concentrate. It will be understood that this is a non-limiting embodiment of how this feed solution may be produced, and that the present disclosure may be applied to such solutions formed by other processes, as described below.

[0041] In an embodiment, a Li.sub.2SO.sub.4 feed solution may be derived from low grade lithium carbonate product, which can be obtained from the brine lithium industry. The low grade lithium carbonate may be reacted with H.sub.2SO.sub.4 to produce the Li.sub.2SO.sub.4 feed solution.

[0042] In another embodiment, the Li.sub.2SO.sub.4 feed solution may be derived from used battery materials, which may be obtained from the battery recycling industry. The used battery materials may be reacted with H.sub.2SO.sub.4 and be leached to produce Li.sub.2SO.sub.4 feed solution.

[0043] In another embodiment, the Li.sub.2SO.sub.4 feed solution may be derived from lithium extracted from hard rock minerals, other than spodumene, such as petalite, lepidolite, zinnwaldite, amblygonite, and eucryptite, and non-hard rock minerals such as hectorite, lithium clays, jadarite and so on. Lithium can be extracted from these minerals using a H.sub.2SO.sub.4 process similar to extracting lithium from spodumene to produce the Li.sub.2SO.sub.4 feed solution. Depending on the mineral, calcination, i.e. phase conversion, and/or acid roasting of the mineral may or may not be required.

[0044] It will be understood that the methods may be performed on a batch basis (i.e., the steps are performed once in sequence for a batch of -spodumene concentrate), or on a continuous basis (e.g., the steps are performed continuously and simultaneously as further -spodumene concentrate is continuously processed to continuously produce further feed solution, to continuously produce further primary lithium product).

[0045] FIGS. 3 to 7 and 10, as described below, are flow charts showing steps of embodiments of the methods of the present disclosure. With the benefit of such flow charts, the person skilled in the art will be able to carry out processes of the described methods using equipment known in the art, such as rotary kiln, various reactors, tanks, thickener, centrifuge, various filters, various driers, ion exchange, water treatment equipment, crystallizer, and other separation equipment, heating equipment, electrolytic cells, electrodialysis cells, and so forth, as may be needed.

Example No. 1: Production of Li.SUB.2.CO.SUB.3 .Primary Lithium Product, and CaSO.SUB.4 .and NaNO.SUB.3 .Byproducts by Reaction of Na.SUB.2.SO.SUB.4 .with a Salt Chemical

[0046] FIG. 3 represents a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 primary lithium product, CaSO.sub.4 and NaNO.sub.3 byproducts, and Li.sub.3PO.sub.4 secondary lithium products. In this example, the CaSO.sub.4 and NaNO.sub.3 byproducts are produced by reaction of a sodium sulfate (Na.sub.2SO.sub.4) intermediate product with a salt chemical of calcium nitrate (Ca(NO.sub.3).sub.2).

[0047] Although Ca(NO.sub.3).sub.2 is used as the salt chemical in this example, it will be understood that other salt chemicals of the group consisting of barium chloride (BaCl.sub.2), calcium chloride (CaCl.sub.2)), copper nitrate (Cu(NO.sub.3).sub.2), nickel chloride (NiCl.sub.2), nickel nitrate (Ni(NO.sub.3).sub.2), potassium carbonate (K.sub.2CO.sub.3), and mixtures thereof, may be used instead of Ca(NO.sub.3).sub.2.

[0048] The reaction of these other salt chemicals with Na.sub.2SO.sub.4 will produce different byproducts, as noted in Table 1 below. These other salt chemicals and byproducts are within the scope of the invention.

TABLE-US-00001 TABLE 1 Salt chemical Byproducts from reaction with Na.sub.2SO.sub.4 barium chloride (BaCl.sub.2) barium sulfate (BaSO.sub.4) and sodium chloride (NaCl) calcium chloride (CaCl.sub.2) calcium sulfate (CaSO.sub.4) and sodium chloride (NaCl) calcium nitrate Ca(NO.sub.3).sub.2 calcium sulfate (CaSO.sub.4) and sodium nitrate (NaNO.sub.3) copper nitrate (Cu(NO.sub.3).sub.2) copper sulfate (CuSO.sub.4) and sodium nitrate (NaNO.sub.3) nickel chloride (NiCl.sub.2) nickel sulfate (NiSO.sub.4) and sodium chloride (NaCl) nickel nitrate (Ni(NO.sub.3).sub.2) nickel sulfate (NiSO.sub.4) and sodium nitrate (NaNO.sub.3) potassium carbonate (K.sub.2CO.sub.3) potassium sulfate (K.sub.2SO.sub.4) and sodium carbonate (Na.sub.2CO.sub.3)

[0049] At step 300, solid -spodumene concentrate may be converted to -spodumene by calcination in a rotary kiln. Calcination is typically performed at temperatures of above 900 C. to convert -spodumene to -spodumene, but the present invention is not limited by a particular temperature.

[0050] At step 302, the produced -spodumene is mixed with sulfuric acid (H.sub.2SO.sub.4) and subjected to acid roasting. Roasting is typically performed at temperatures of about 250 C. to form water soluble lithium sulfate (Li.sub.2SO.sub.4), but the present invention is not limited by a particular temperature.

[0051] In steps 300 and 302, the heat required by kiln calcination and acid roasting is produced by combustion of fossil fuels in the current lithium extraction industry. This produces flue gases, including CO.sub.2 gas, which may be diverted for use in the process as described below, rather than emitted into the atmosphere.

[0052] At step 304, the acid-roasted material is mixed with water in leaching tanks where lithium and other metal impurities are leached into solution. For solution purification, generally, limestone powder (CaCO.sub.3), lime (CaO) or hydrated lime (Ca(OH).sub.2), NaOH, Na.sub.2CO.sub.3 or any other reagent which can precipitate impurities is or are added into the solution to change the pH and remove impurities and the overdosed SO.sub.4.sup.2 in acid roasting. By solid/liquid (S/L) separation, leaching residue and impurity residue may be separated and PLS (pregnant leach solution) solution is obtained. If necessary, an ion exchange (IX) circuit may be further used to remove Ca and Mg impurities. By this purification, clean PLS solution comprising Li.sub.2SO.sub.4 is obtained. Step 304 results in the production of aqueous solution comprising lithium sulfate (Li.sub.2SO.sub.4), which is considered to be an example of a feed solution in the present invention.

[0053] At step 306, sodium carbonate (Na.sub.2CO.sub.3) solution may be added to the PLS solution comprising Li.sub.2SO.sub.4. The Li.sub.2SO.sub.4 PLS reacts with Na.sub.2CO.sub.3 to precipitate lithium carbonate (Li.sub.2CO.sub.3) in a Na.sub.2SO.sub.4 solution. The produced Li.sub.2CO.sub.3 can be separated from the sodium sulfate solution by precipitation at a temperature, for example being about 95 C. (The solubility of Li.sub.2CO.sub.3 decreases as the temperature of the solution increases.) The precipitated Li.sub.2CO.sub.3 may be separated from a mother liquor and dried as Li.sub.2CO.sub.3 product. The Na.sub.2CO.sub.3 may be considered to be an example of a primary reagent in the present invention, and the Li.sub.2CO.sub.3 may be considered to be an example of a primary lithium product in the present invention.

[0054] If battery-grade product is desired, then the wet Li.sub.2CO.sub.3 cake obtained may be re-dissolved and, at step 308, further purified by a CO.sub.2 method, known in the prior art. In general, the aforementioned CO.sub.2 method involves reacting Li.sub.2CO.sub.3 product with CO.sub.2 to produce soluble LiHCO.sub.3. Insoluble impurities, such as iron, magnesium, and calcium may be removed from the solution. The CO.sub.2 may be then removed, such as by increasing the temperature of the solution, to precipitate pure Li.sub.2CO.sub.3. The wet Li.sub.2CO.sub.3 obtained after filtration is dried to produce a final battery-grade Li.sub.2CO.sub.3 product. Magnetic impurity removal in some parts of process and micronizing steps to reduce the Li.sub.2CO.sub.3 product to a desired particle size before final packing may be performed on the Li.sub.2CO.sub.3 product.

[0055] The mother liquor that was separated from the precipitated Li.sub.2CO.sub.3 at step 306 comprises Na.sub.2SO.sub.4.

[0056] At step 310, the mother liquor may be mixed with calcium nitrate (Ca(NO.sub.3).sub.2) so that the Na.sub.2SO.sub.4 of the mother liquor and the Ca(NO.sub.3).sub.2 react to convert the Na.sub.2SO.sub.4 to calcium sulfate (CaSO.sub.4) and sodium nitrate (NaNO.sub.3, which may be represented by the following equation:

[00001]$\begin{array}{cc}{\mathrm{Na}}_2{\mathrm{SO}}_{4\left(\mathrm{aq}\right)}+C{a\left(N{O}_3\right)}_2.fwdarw.{\mathrm{CaSO}}_{4\left(s\right)}+2\mathrm{NaN}{O}_{3\left(\mathrm{aq}\right)}& \left(\mathrm{Eqn}.1\right)\end{array}$

[0057] The CaSO.sub.4 and NaNO.sub.3 may be considered to be an example of a byproduct in the present invention. This reaction of Eqn. 1 may take place at a variety of combinations of pressure and temperature, including at atmospheric pressure and room temperature (i.e., about 20 C.). In embodiments, Ca(NO.sub.3).sub.2 may be introduced into the vessel in solid form. In other embodiments, Ca(NO.sub.3).sub.2 may be introduced into the vessel in aqueous solution, as Ca(NO.sub.3).sub.2 has relatively high solubility in water. The CaSO.sub.4 precipitates as a solid, as it has relatively low solubility in water at room temperature. The NaNO.sub.3 remains in solution, as it has relatively high solubility in water at room temperature.

[0058] For the Na.sub.2SO.sub.4 conversion reaction, the Na.sub.2SO.sub.4 concentration in the solution or slurry may be 5 to 35 wt %, and the Ca(NO.sub.3).sub.2/Na.sub.2SO.sub.4 molar ration may be 0.8 to 2, and the resulted conversion rate may be in 70% to 99%. Preferably, the Na.sub.2SO.sub.4 concentration in the solution or slurry may be between 10 to 30 wt %, and the Ca(NO.sub.3).sub.2/Na.sub.2SO.sub.4 molar ration may be between 1 to 1.6, and the resulted conversion rate may be between 85 to 99%. Most preferably, the Na.sub.2SO.sub.4 concentration in the solution or slurry may be between 15 to 25 wt %, and the Ca(NO.sub.3).sub.2/Na.sub.2SO.sub.4 molar ration may be between 1 to 1.1, and the resulted conversion rate may be between 90 to 97%. The precipitated CaSO.sub.4 may be separated from NaNO.sub.3 solution with regular, low cost equipment, with non-limiting examples including clarifiers, thickeners for gravity settling, or mechanical filters. In embodiments, the NaNO.sub.3 may be left to remain in solution.

[0059] In embodiments, if NaNO.sub.3 in solid form is desired, the NaNO.sub.3 may be crystallized by evaporation using a crystallization circuit, and condensed water produced from the crystallization circuit can be re-used in the process at step 304.

[0060] In comparison with the prior art process shown in FIG. 1, a person skilled in the art would appreciate that the method shown in FIG. 3 may be advantageous as follows. First, a crystallization circuit for treating the Na.sub.2SO.sub.4 may be avoided or at least be reduced in capacity, thus reducing its associated capital and operating cost. Second, in comparison with Na.sub.2SO.sub.4, CaSO.sub.4 and NaNO.sub.3 typically have a higher market value and different industrial applications. For example, CaSO.sub.4 may be used as construction material, or as a feed material for cement production. NaNO.sub.3 may be used as fertilizer in agriculture or as explosive in mining industries and construction industries. Third, NaNO.sub.3 may also be kept in a solution form for sale to market. As illustrated, the embodiment according to the instant disclosure can significantly reduce the energy consumption of the overall process by avoiding the need for evaporation.

[0061] The solution resulting from step 310 may contain residual lithium. In step 312, the residual lithium may be recycled to produce a lithium material that is additional to the Li.sub.2CO.sub.3 produced in step 308. This increases the total recovery of lithium produced by the instant method.

[0062] In embodiments, at step 312, phosphoric acid (H.sub.3PO.sub.4) may be added to the solution resulting from step 310. The phosphate ions, PO.sub.4.sup.3 will react with the lithium ions Lit in the solution to form lithium phosphate (Li.sub.3PO.sub.4), as follows.

[00002]$\begin{array}{cc}3{\mathrm{Li}}_{\left(\mathrm{aq}\right)}^{+}+{\mathrm{PO}}_{4\left(\mathrm{aq}\right)}^{3-}.fwdarw.{\mathrm{Li}}_{3}P{O}_{4\left(s\right)}& \left(\mathrm{Eqn}.2\right)\end{array}$

[0063] The H.sub.3PO.sub.4 may be considered to be an example of a secondary reagent in the present invention, and the Li.sub.3PO.sub.4 may be considered to be an example of a secondary lithium product in the present invention. Li.sub.3PO.sub.4 has poor solubility in water at room temperature, and will precipitate as a solid. Li.sub.3PO.sub.4 is another important feed material for production of lithium batteries.

[0064] In embodiments, and as illustrated in FIG. 3, step 312 is shown as being performed after step 310. In other embodiments, step 312 may be performed directly on the mother liquor resulting from step 306, before performing step 310. It will be appreciated that this alternative embodiment is within the scope of the present invention.

Example No. 2: Production of LiOHH.SUB.2.O Primary Lithium Product, and CaSO.SUB.4 .and NaNO.SUB.3 .Byproducts by Reaction of Na.SUB.2.SO.SUB.4 .with a Salt Chemical

[0065] FIG. 4 represents a flow chart of an embodiment of the present invention, there is provided a method for processing -spodumene concentrate to produce a LiOHH.sub.2O primary lithium product, and CaSO.sub.4 solid and NaNO.sub.3 solution byproducts, and optionally Li.sub.3PO.sub.4 secondary lithium products. In this example, the CaSO.sub.4 and NaNO.sub.3 byproducts are produced by reaction of a sodium sulfate (Na.sub.2SO.sub.4) intermediate product with a salt chemical of Ca(NO.sub.3).sub.2. As noted above in respect to the method of FIG. 3, although Ca(NO.sub.3).sub.2 is used as the salt chemical in this example, it will be understood that other salt chemicals may be used to produce other byproducts. Some of the salt chemicals are summarized in the Table 1, above.

[0066] In the method of FIG. 4, steps 300, 302, 304 are analogous to the same numbered steps of the method illustrate in FIG. 3. As such, the description of those steps applies to the respective analogous step in the method of FIG. 4, with the necessary adjustments.

[0067] As to step 406 of FIG. 4, NaOH may be added to the PLS solution comprising Li.sub.2SO.sub.4. The Li.sub.2SO.sub.4 PLS reacts with NaOH to form a solution of a mixture of LiOH and Na.sub.2SO.sub.4, as shown below. The NaOH may be considered to be an example of a primary reagent in the present invention, and the LiOH or LiOHH.sub.2O may be considered to be an example of a primary lithium product in the present invention, this Na.sub.2SO.sub.4 solution may be referred to as an intermediate solution in the present invention, to distinguish it from the feed solution.

[00003]$\begin{array}{cc}L{i}_2{\mathrm{SO}}_{4\left(aq\right)}+2{\mathrm{NaOH}}_{\left(aq\right)}.fwdarw.{\mathrm{Na}}_2{\mathrm{SO}}_{4\left(aq\right)}+2{\mathrm{LiOH}}_{\left(aq\right)}& \left(\mathrm{Eqn}.3\right)\end{array}$

[0068] At step 408 of FIG. 4, the solution resulting from step 406 may be subjected to freezing treatment by lowering its temperature. The solubility of LiOH at freezing temperatures is greater than the solubility of Na.sub.2SO.sub.4 at freezing temperatures in the rage between 0 C. and 15 C. Thus, as a result of the freezing treatment, Na.sub.2SO.sub.4 may be separated from solution in the form of the decahydrate of sodium sulfate (Na.sub.2SO.sub.4-10H.sub.2O), which is known as Glauber's salt.

[0069] At step 410 of FIG. 4, the Na.sub.2SO.sub.4-removed LiOH PLS solution resulting from step 408 may be subjected to crystallization to produce a wet LiOH cake.

[0070] The wet LiOH cake may be dried to produce a final LiOHH.sub.2O product. If battery-grade product is desired, the produced wet LiOH cake may be re-dissolved and subjected to secondary or tertiary crystallization, as required. Usually, magnetic impurity removal in some parts of process and micronizing before packaging may be performed for battery grade product.

[0071] At step 412 of FIG. 4, the Glauber's salt that is produced from the freezing separation process of step 408 may be re-dissolved in water to produce a solution of Na.sub.2SO.sub.4.

[0072] At step 414 of FIG. 4, the solution of Na.sub.2SO.sub.4 resulting from step 412 may be mixed with Ca(NO.sub.3).sub.2 so that the Na.sub.2SO.sub.4 and the Ca(NO.sub.3).sub.2 react to convert the Na.sub.2SO.sub.4 to CaSO.sub.4 and NaNO.sub.3 (see Eqn. 1). This reaction is analogous to the reaction described above in step 310 of the method as illustrated in FIG. 3. As such, it will be understood that such description applies in the context of step 414 of FIG. 4. The CaSO.sub.4 and NaNO.sub.3 may be considered to be an example of a byproduct in the present invention.

[0073] The solution resulting from step 414 may contain residual lithium. In step 416, this residual lithium may be recycled to produce lithium materials that are additional to the LiOH produced in step 410. This increases the total recovery of lithium produced by the method as illustrated in FIG. 4.

[0074] In an embodiment and as illustrated in step 416 of FIG. 4, phosphoric acid (H.sub.3PO.sub.4) may be added to the solution resulting from step 414 to yield Li.sub.3PO.sub.4. These reactions are analogous to the reactions described above in step 312 of the method illustrated in FIG. 3. As such, it will be understood that such description applies in the context of step 416 of FIG. 4.

[0075] In an embodiment illustrated in FIG. 4, step 416 may be performed after step 414. In other embodiments, step 416 may be performed directly on the solution resulting from step 412, and before performing 414. This alternative embodiment is within the scope of the present invention.

Example No. 3: Production of Li.SUB.2.CO.SUB.3 .Lithium Product, and CaSO.SUB.4 .and NaOH Byproducts by Reaction of Na.SUB.2.SO.SUB.4 .with an Alkali Chemical

[0076] FIG. 5 represents a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 primary lithium product, CaSO.sub.4 and NaOH byproducts, and optionally Li.sub.2CO.sub.3 or Li.sub.3PO.sub.4 secondary lithium products. In this example, the CaSO.sub.4 and NaOH byproducts may be produced by reaction of a sodium sulfate (Na.sub.2SO.sub.4) intermediate product with an alkali chemical of calcium hydroxide (Ca(OH).sub.2).

[0077] Although Ca(OH).sub.2 is used as the alkali chemical in this example and as illustrated in FIG. 5, it will be understood that other alkali chemicals selected from the group consisting of ammonium hydroxide (NH.sub.4OH), barium hydroxide (Ba(OH).sub.2), potassium hydroxide (KOH), and mixtures of any of the foregoing, may be used instead of Ca(OH).sub.2. The reaction of these other alkali chemicals with Na.sub.2SO.sub.4 may produce different byproducts, as noted in Table 2 below.

TABLE-US-00002 TABLE 2 Alkali chemical Byproducts from reaction with Na.sub.2SO.sub.4 ammonium hydroxide (NH.sub.4OH) ammonium sulfate ((NH.sub.4).sub.2SO.sub.4) and sodium hydroxide (NaOH) barium hydroxide (Ba(OH).sub.2) barium sulfate (BaSO.sub.4) and sodium hydroxide (NaOH) calcium hydroxide Ca(OH).sub.2 calcium sulfate (CaSO.sub.4) and sodium hydroxide (NaOH) potassium hydroxide (KOH) potassium sulfate (K.sub.2SO.sub.4) and sodium hydroxide (NaOH)

[0078] In the method as illustrated in FIG. 5, steps 300, 302, 304, 306, 308 are analogous to the same numbered steps of the method as illustrated FIG. 3. As such, it will be understood that description of those steps applies to the respective analogous step in the method of FIG. 5.

[0079] The mother liquor that was separated from the precipitated Li.sub.2CO.sub.3 at step 306 comprises Na.sub.2SO.sub.4. At step 500, the mother liquor may be mixed with Ca(OH).sub.2 so that the Na.sub.2SO.sub.4 of the mother liquor and the Ca(OH).sub.2 react to convert the Na.sub.2SO.sub.4 to CaSO.sub.4 solid and NaOH solution as follows.

[00004]$\begin{array}{cc}{\mathrm{Na}}_2{\mathrm{SO}}_{4\left(\mathrm{aq}\right)}+\mathrm{Ca}{\left(\mathrm{OH}\right)}_{2\left(\mathrm{aq}\right)}.fwdarw.{\mathrm{CaSO}}_{4\left(s\right)}+2{\mathrm{NaOH}}_{\left(\mathrm{aq}\right)}& \left(\mathrm{Eqn}.4\right)\end{array}$

[0080] The CaSO.sub.4 and NaOH may be considered to be an example of a byproduct in the present invention. This reaction may take place at a variety of combinations of pressure and temperature, including at atmospheric pressure and room temperature (i.e., about 20 C.). The CaSO.sub.4 precipitates as a solid since it has relatively low solubility in water at room temperature. The NaOH remains in solution as it has relatively high solubility in water at room temperature. For the Na.sub.2SO.sub.4 conversion reaction, the Na.sub.2SO.sub.4 concentration in the solution or slurry can be 5 to 35 wt %, and the Ca(OH).sub.2/Na.sub.2SO.sub.4 molar ration can be 0.7 to 2.5, and the resulted conversion rate can be in 60% to 98% Preferably, the Na.sub.2SO.sub.4 concentration in the solution or slurry may be between 10 to 30 wt %, and the Ca(OH).sub.2/Na.sub.2SO.sub.4 molar ration may be between 0.9 to 2, and the resulted conversion rate may be between 70 to 96%. Most preferably, the Na.sub.2SO.sub.4 concentration in the solution or slurry may be between 15 to 25 wt %, and the Ca(OH).sub.2/Na.sub.2SO.sub.4 molar ration may be between 1 to 1.5, and the resulted conversion rate may be between 85 to 95%. The precipitated CaSO.sub.4 may be separated from NaOH solution with regular, low cost equipment, with non-limiting examples including clarifiers or thickeners for gravity settling, or mechanical filters. In embodiments, the NaOH may be left to remain in solution. In other embodiments, if NaOH in solid form is desired, the NaOH may be crystallized by evaporation using a crystallization circuit, and condensed water produced from the crystallization circuit can be re-used in the process at step 304.

[0081] In comparison with the prior art process shown in FIG. 1, the same relative advantages noted in respect to the method of FIG. 3 apply equally to the method of FIG. 5, albeit substituting the NaOH solution product in the method of FIG. 5 for NaNO.sub.3 product in the method of FIG. 3. NaOH typically has higher market value than the feeding Na.sub.2SO.sub.4 and the Ca(OH).sub.2 used to produce the NaOH. In addition, NaOH can optionally be re-introduced to the process upstream of the PLS purification process in step 304 to reduce reagent cost.

[0082] The solution resulting from step 500 may contain residual lithium. At step 502, the residual lithium may be used to produce lithium materials that are additional to the Li.sub.2CO.sub.3 produced in step 308. In one embodiment of step 502, CO.sub.2 gas is reacted with lithium in the solution resulting from step 500 in accordance with Eqn. 5, to yield Li.sub.2CO.sub.3.

[00005]$\begin{array}{cc}2{\mathrm{LiOH}}_{\left(\mathrm{aq}\right)}+{\mathrm{CO}}_{2\left(g\right)}.fwdarw.{\mathrm{Li}}_{2}C{O}_{3\left(s\right)}+H_2{O}_{\left(aq\right)}& \left(\mathrm{Eqn}.5\right)\end{array}$

[0083] In embodiments as illustrated at step 502 of FIG. 5, phosphoric acid (H.sub.3PO.sub.4) may be added to the solution resulting from step 500 to yield Li.sub.3PO.sub.4. This reaction is analogous to the reactions described above in step 312 of the method of FIG. 3 and in step 416 of the method of FIG. 4. As such, it will be understood that such description applies in the context of step 502 of FIG. 5.

[0084] The CO.sub.2 used in step 502 may be obtained from a variety of sources. In one embodiment, the CO.sub.2 may be separated from a flue gas of an industrial process, which may be of the same lithium plant. In another embodiment, the flue gas may result from the combustion of fossil fuels to produce heat for calcination of the -spodumene concentrate in step 300 of the method, and/or for acid roasting of the -spodumene in step 302 of the method, and/or for steam generation by a boiler in a utilities area of the plant. The generated steam may be used throughout the process, as known in the prior art. If so, then CO.sub.2 emissions from the lithium plant can be reduced. In a further embodiment, the CO.sub.2 may be obtained from open air, which will reduce the CO.sub.2 number in a global way. Suitable equipment and processes are known in the prior art for separation of CO.sub.2 gas from flue gas. Non-limiting examples include physical or chemical absorption-based methods (e.g., using monoethanolamine (MEA) solvent, caustic, ammonia solution), physical or chemical adsorption-based methods (e.g. using molecular sieves. activated carbon, metallic oxides), cryogenic methods, and membrane-based methods that rely on gas separation, or gas absorption phenomena, as known in the prior art. Non-CO.sub.2 components of the flue gas may optionally be treated before being emitted to the atmosphere, sequestered, or otherwise treated in some manner.

[0085] Further, it will be understood that a portion or all of the Li.sub.2CO.sub.3 produced by step 502 may be separated and sold to market as a product.

[0086] In embodiments as illustrated in FIG. 5, step 502 is shown as being performed after step 500. In other embodiments, step 502 may be performed directly on the mother liquor resulting from step 306, and before performing step 500. This alternative embodiment is within the scope of the present invention.

Example No. 4: Production of LiOHH.SUB.2.O Primary Lithium Product, and CaSO.SUB.4 .and NaOH Byproducts by Reaction of Na.SUB.2.SO.SUB.4 .with an Alkali Chemical

[0087] FIG. 6 represents a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce LiOHH.sub.2O, and converting a Na.sub.2SO.sub.4 intermediate product to a byproduct of solid CaSO.sub.4 and a solution of NaOH, using an alkali chemical of Ca(OH).sub.2. As noted above in respect to the method of FIG. 5, other alkali chemicals (e.g., NH.sub.4OH, Ba(OH).sub.2, KOH) or mixtures of them, may be used instead to produce different byproducts as summarized in Table 2.

[0088] In embodiments, as illustrated in FIG. 6, steps 300, 302, 304, are analogous to the same numbered steps of the method illustrated in FIG. 3, and steps 406, 408, 410, and 412 are analogous to same numbered steps of the method illustrated in FIG. 4. As such, it will be understood that description of those steps may apply to the respective analogous step in the method illustrated in FIG. 6.

[0089] At step 412 of FIG. 6, the Glauber's salt that is produced from the freezing separation process of step 408 may be re-dissolved in water to produce a solution of Na.sub.2SO.sub.4.

[0090] At step 600 of FIG. 6, the solution of Na.sub.2SO.sub.4 resulting from step 412 may be mixed with Ca(OH).sub.2 so that the dissolved Na.sub.2SO.sub.4 and the Ca(OH).sub.2 react to convert the Na.sub.2SO.sub.4 to CaSO.sub.4 and NaOH. This reaction is analogous to the reaction described above in step 500 of the method illustrated in FIG. 5. As such, it will be understood that such description may apply in the context of step 600 of FIG. 6. A portion or all of the NaOH may be sold to market as a product. In addition or in alternative, a portion or all of the NaOH may optionally be re-introduced to the process for use in the PLS purification process of step 304. In addition or in alternative, a portion or all of the NaOH may optionally be re-introduced to the process for use in the LiOH conversion process of step 406.

[0091] The solution resulting from step 600 may contain residual lithium. This residual lithium may be used to produce lithium materials that are additional to the LiOH produced in step 410. In embodiments as illustrated in FIG. 6 at step 602, CO.sub.2 gas may react with lithium in the solution resulting from step 600 to yield Li.sub.2CO.sub.3. In embodiments as illustrated in FIG. 6 at step 602, phosphoric acid (H.sub.3PO.sub.4) may be added to the solution resulting from step 600 to yield Li.sub.3PO.sub.4. These reactions are analogous to the reactions described above in step 502 of the method illustrated in FIG. 5. As such, it will be understood that such description applies in the context of step 602 of FIG. 6. In embodiments as illustrated in FIG. 6, step 602 is shown as being performed after step 600. In alternative embodiments, step 602 may be performed directly on the solution resulting from step 412, before performing step 600. This alternative embodiment is within the scope of the present invention.

Example No. 5: Production of Li.SUB.2.CO.SUB.3 .Primary Lithium Product, and NaOH and H.SUB.2.SO.SUB.4 .Byproducts by Electrolysis or Electrodialysis of Na.SUB.2.SO.SUB.4

[0092] FIG. 7 represents a flow chart of an embodiment of a method of the present invention for processing -spodumene concentrate to produce a Li.sub.2CO.sub.3 primary lithium product, and NaOH and H.sub.2SO.sub.4 byproducts. In this example, the NaOH and H.sub.2SO.sub.4 byproducts are produced by electrolysis or electrodialysis of a Na.sub.2SO.sub.4 intermediate product, which is being used as the electrolyte.

[0093] In embodiments as illustrated in FIG. 7, steps 300, 302, 304, 306, 308, are analogous to same numbered steps of the method of FIG. 3. As such, it will be understood that description of those steps may also apply to the respective analogous step in the method of FIG. 7.

[0094] The mother liquor that was separated from the precipitated Li.sub.2CO.sub.3 at step 306 comprises Na.sub.2SO.sub.4. As illustrated in FIG. 7, at step 700, the mother liquor may be subjected to either electrolysis, or electrodialysis, or both of them, so that the Na.sub.2SO.sub.4, used as the electrolyte, may be converted to separate streams of NaOH solution and H.sub.2SO.sub.4 solution, as follows.

[0095] The NaOH and H.sub.2SO.sub.4 streams may be separated automatically as a result of electrolysis or electrodialysis, without need for further separating processing.

[00006]$\begin{array}{cc}{\mathrm{Na}}_2{\mathrm{SO}}_4+2H_{2}O\stackrel{\mathrm{Electrolysis}}{.Math.}2\mathrm{NaOH}+H_2{\mathrm{SO}}_4& \left(\mathrm{Eqn}.6a\right)\end{array}$$\begin{array}{cc}{\mathrm{Na}}_2{\mathrm{SO}}_4+2H_{2}O\stackrel{\mathrm{Electrodialysis}}{.Math.}2\mathrm{NaOH}+H_2{\mathrm{SO}}_4& \left(\mathrm{Eqn}.6b\right)\end{array}$

[0096] The principles of electrolysis or electrodialysis are well understood to the person of ordinary skill in the art, and as such, they are not described in detail herein. For completeness, FIG. 8 represents a schematic diagram illustrating Na.sub.2SO.sub.4 conversion to NaOH and H.sub.2SO.sub.4 with an embodiment of an electrolysis process. FIG. 9 represents a schematic diagram illustrating Na.sub.2SO.sub.4 conversion to NaOH and H.sub.2SO.sub.4 with an embodiment of a bipolar membrane electrodialysis (BMED) method. Electrolysis or electrodialysis have their respective advantages, but both may be used to realize the Na.sub.2SO.sub.4 conversion as desired.

[0097] The difference between electrolysis and electrodialysis is as follows. Electrolysis uses one or more electrolysis cells with each cell having a positive electrode and a negative electrode. In contrast, electrodialysis uses one or more electrodialysis chambers combined together, but having only one positive electrode and negative electrode at two ends of the combined stack.

[0098] In comparison with the prior art process shown in FIG. 1, step 700 as illustrated in FIG. 7 may be advantageous at least in the following respects. First, a crystallization circuit for treating the Na.sub.2SO.sub.4 may be avoided or at least be reduced in capacity, to reduce its associated capital and operating cost.

[0099] Second, NaOH and H.sub.2SO.sub.4 typically have higher value and better marketability potential than the Na.sub.2SO.sub.4. As such, a portion or all of the NaOH stream and H.sub.2SO.sub.4 stream may be sold directly on market.

[0100] Third, in addition or in the alternative, a portion or all of the NaOH stream may be re-used in the process to reduce the reagent cost of the method herein disclosed. Further, by doing so, any lithium that is contained in the NaOH stream may be kept in the process, which may improve the total lithium recovery in the method disclosed herein, in comparison to the conventional process of FIG. 1.

[0101] A portion or all of the NaOH stream resulting from step 700 may be re-used to the PLS purification process of step 304 of the method disclosed herein.

[0102] Fourth, a portion or all of the H.sub.2SO.sub.4 stream resulting from step 700 may be re-used in the acid roasting process of step 302 to reduce the reagent cost of the method. Further, by doing so, any lithium that is contained in the H.sub.2SO.sub.4 stream may be kept in the process, which may improve the total lithium recovery in the method, in comparison to the conventional process of FIG. 1.

[0103] Step 700 as illustrated in FIG. 7 may also result in the production of a bleed liquori.e., the Na.sub.2SO.sub.4 electrolyte stream that is not converted to H.sub.2SO.sub.4 or NaOH and flows out from the electrolytic cell or electrolytic chamber, and has a lower Na.sub.2SO.sub.4 concentration than the electrolyte stream that flows into the electrolytic cell or electrolytic chamber. The bleed liquor may be directed to upstream of the leaching process of step 304 to make slurry from the acid-roasted spodumene.

Example No. 6: Production of LiOHH.SUB.2.O Primary Lithium Product, and NaOH and H.SUB.2.SO.SUB.4 .Byproducts by Electrolysis or Electrodialysis of Na.SUB.2.SO.SUB.4

[0104] FIG. 10 represents a flow chart for an embodiment of a method of the present invention for processing -spodumene concentrate to produce a LiOHH.sub.2O primary lithium product, NaOH and H.sub.2SO.sub.4 byproducts. In this example, the NaOH and H.sub.2SO.sub.4 byproducts may be produced by electrolysis or electrodialysis of a Na.sub.2SO.sub.4 intermediate product, being used as the electrolyte, as illustrated in FIGS. 8, 9 and 10.

[0105] In embodiments, steps 300, 302, and 304 of the method illustrated in FIG. 10 are analogous to same numbered steps of the method illustrated in FIG. 3, and steps 406, 408, 410 and 412, are analogous to same numbered steps of the method of FIG. 4. As such, it will be understood that description of those steps may also apply to the respective analogous steps in the method illustrated in FIG. 10.

[0106] At step 412 of FIG. 10, the Glauber's salt that is produced from the freezing separation process of step 408 may be re-dissolved in water to produce a solution of Na.sub.2SO.sub.4. At step 1000, the solution of Na.sub.2SO.sub.4 resulting from step 412 may be subjected to either electrolysis, or electrodialysis, or both of them, so that the dissolved Na.sub.2SO.sub.4, used as the electrolyte, may be converted to separate streams of NaOH solution and H.sub.2SO.sub.4 solution. This reaction is analogous to the reaction described above in step 700 of the method illustrated in FIG. 7. As such, it will be understood that such description applies in the context of step 1000 of FIG. 10, with the necessary adaptations.

[0107] A portion or all of the NaOH stream and H.sub.2SO.sub.4 stream may be sold directly on market. In addition or in the alternative, a portion or all of the NaOH stream may be re-used in the process to reduce the reagent cost of the method. Further, by doing so, any residual lithium that is contained in the NaOH stream will thereby be kept in the process, which may improve the total lithium recovery in the method, as compared with the conventional process of FIG. 2.

[0108] A portion or all of the NaOH stream resulting from step 1000 may be re-used in the process in one or all of the following ways. A portion or all of the NaOH stream may be re-used in the PLS purification process of step 304 of the method. In addition or in the alternative, a portion or all of the NaOH stream may optionally be re-used in the LiOH conversion process of step 406 of the method illustrated in FIG. 10.

[0109] A portion or all of the H.sub.2SO.sub.4 stream resulting from step 1000 may be re-used in the acid roasting process of step 302 to reduce the reagent cost of the method. Further, by doing so, any lithium that is contained in the H.sub.2SO.sub.4 stream may be kept in the process, which may improve the total lithium recovery in the method, as compared with the conventional process of FIG. 2, known in the prior art.

[0110] Step 1000 may also result in the production of a bleed liquori.e., the Na.sub.2SO.sub.4 electrolyte stream that is not converted to H.sub.2SO.sub.4 or NaOH and flows out from the electrolytic cell or electrolytic chamber, and has a lower Na.sub.2SO.sub.4 concentration than the electrolyte stream that flows into the electrolytic cell or electrolytic chamber. The bleed liquor may be directed to upstream of the leaching process of step 304 to make slurry from the acid-roasted spodumene.

Definitions

[0111] References in the specification to one embodiment, an embodiment, etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.

[0112] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as solely, only, and the like, in connection with the recitation of claim elements or use of a negative limitation. The terms preferably, preferred, prefer, optionally, may, and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[0113] Alkali chemical, as used herein, refers to a chemical selected from the group consisting of calcium hydroxide (Ca(OH).sub.2), ammonium hydroxide (NH.sub.4OH), barium hydroxide (Ba(OH).sub.2), potassium hydroxide (KOH), and mixtures of any of the foregoing.

[0114] Flue gas, as used herein, refers to a gas comprising CO.sub.2 gas produced as an emission from the combustion of a fossil fuel. As non-limiting examples, flue gas may be CO.sub.2 gas mixed with non-CO.sub.2 gases such as water vapor, oxygen, carbon monoxide, nitrogen oxides, and sulfur oxide.

[0115] Salt chemical, as used herein, refers to a chemical selected from the group consisting of barium chloride (BaCl), calcium chloride (CaCl.sub.2)), calcium nitrate (Ca(NO.sub.3).sub.2), copper nitrate (Cu(NO.sub.3).sub.2), nickel chloride (NiCl.sub.2), nickel nitrate (Ni(NO.sub.3).sub.2), potassium carbonate (K.sub.2CO.sub.3), and any mixtures of the foregoing.

[0116] The singular forms a, an, and the include the plural reference unless the context clearly dictates otherwise. The term and/or means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase one or more is readily understood by one of skill in the art, particularly when read in context of its usage.

[0117] The term about can refer to a variation of 5%, 10%, 20%, or 25% of the value specified. For example, about 50 percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term about can include one or two integers greater than and/or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term about is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[0118] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

[0119] As used herein, the term comprising is intended to mean that the list of elements following the word comprising are required or mandatory but that other elements are optional and may or may not be present. As used in this specification and claim(s), the words comprising (and any form of comprising, such as comprise and comprises), having (and any form of having, such as have and has), including (and any form of including, such as include and includes) or containing (and any form of containing, such as contain and contains), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0120] As used herein, the term consisting of is intended to mean including and limited to whatever follows the phrase consisting of. Thus, the phrase consisting of indicates that the listed elements are required or mandatory and that no other elements may be present.

[0121] It is noted that terms like preferably, commonly, generally, and typically are not utilized herein to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that can or cannot be utilized in a particular embodiment of the present invention.

[0122] For the purposes of describing and defining the present invention it is noted that the term substantially is utilized herein to represent the inherent degree of uncertainty that can be attributed to any quantitative comparison, value, measurement, or other representation. The term substantially is also utilized herein to represent the degree by which a quantitative representation can vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0123] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges recited herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof, as well as the individual values making up the range, particularly integer values. A recited range includes each specific value, integer, decimal, or identity within the range. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc.

[0124] As will also be understood by one skilled in the art, all language such as up to, at least, greater than, less than, more than, or more, and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

[0125] Features and advantages of the subject matter hereof will become more apparent in light of the following detailed description of selected embodiments, as illustrated in the accompanying figures. As will be realized, the subject matter disclosed and claimed is capable of modifications in various respects, all without departing from the scope of the claims. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive and the full scope of the subject matter is set forth in the claims.