PROCESSO PARA A SEPARAÇÃO DE ÍONS DE LI E NA E DISPOSITIVO PARA EFETUAR DITO PROCESSO

Abstract

The invention relates to a method for separating Li ions and Na ions from sulfate-containing solutions, and to a device for carrying out the method.

Description

1 / 8 PROCESS FOR SEPARATING Li AND Na IONS AND DEVICE FOR CARRYING OUT SAID PROCESS FIELD OF THE INVENTION

[001] The present invention relates to a process for separating Li and Na ions from solutions containing sulfate, and to a device for carrying out the process. FUNDAMENTALS OF THE INVENTION

[002] Electric vehicles powered by electricity from low-emission sources are considered to have the greatest potential for climate protection among land transport technologies as seen through their life cycle.

[003] Therefore, electromobility is considered a key component of a sustainable and climate-friendly traffic system based on renewable energies.

[004] The focus is on lithium-ion / polymer batteries as a promising storage system as the basis for electric propulsion, which, however, have only a limited lifespan. In this respect, the desired degree of electrification can only be achieved in combination with a sustainable recycling concept. In particular, the planned ban on sales of new cars with internal combustion engines necessitates a holistic recovery of the precious metals contained in spent batteries, such as cobalt, nickel and manganese, but also lithium, which is obtainable only through lengthy processes.

[005] The previous technique describes a number of processes dealing with the recovery of precious metals from spent lithium-ion / polymer batteries.

[006] U.S. Patent Application 2017 / 0077564A1 relates to a process for recycling lithium-ion batteries, comprising: (i) identifying a molar ratio for cathode materials for a new battery; Petition 870250079841, dated 05 / 09 / 2025, page 9 / 72 2 / 8 (ii) forming a leaching solution by combining comminuted battery material from a lithium battery recycling stream with an acidic leaching agent and hydrogen peroxide (H2O2) to separate cathode materials from undissolved materials; (iii) filtering the undissolved materials from the leaching solution formed so that the dissolved salts of the cathode materials remain in the leaching solution; (iv) determining a composition of said leaching solution by identifying a molar ratio of the cathode material salts dissolved therein; (v) adding Ni, Co, Mn or Al salts in the form of sulfates (xSO4) based on the determined composition in order to adjust the molar ratio of the cathode material salts dissolved in the leaching solution to match the identified molar ratio for the recycled battery, including the addition of an aluminum sulfate solution and a chelating agent;(vi) increase the pH of the leaching solution to at least 10 to precipitate and separate by filtration the metal ions from the cathode materials in order to form a pCAM precursor for the actual active CAM cathode material, in which the Ni, Co, Mn and Al salts remaining in solution are present in the form of hydroxide (OH)2 or carbonate (CO3) combined with the desired molar ratio for the new CAM. Subsequently, the precursor is carefully mixed with LiOH*H2O or Li2CO3, and reacted with the active cathode material at temperatures >800°C.;

[007] US patent application 2013 / 0302226A1 describes a process for recycling batteries in which a solution of battery aggregate materials is produced from spent cells, impurities are precipitated from the produced solution, a predetermined ratio of desired materials is adjusted to the solution, and the desired material is precipitated and further processed into a cathode material for new batteries.

[008] However, the materials described in the prior art have the disadvantage that, due to the nature of the process management, the lithium to be recovered is present in the form of Li2SO4 in solution along with Na2SO4, so that it can be recovered as moderately saturated Li2CO3. Petition 870250079841, dated 05 / 09 / 2025, page 10 / 72 3 / 8 is soluble only near the end of the process chain. Due to the solubility relationships of U2CO3 and Na2CO3, as well as Na2SO4 and U2SO4, the separation of Na and Li ions is very complicated in detail, and makes the actual quantitative recovery of lithium virtually impossible from an economic standpoint.

[009] Thus, in order to achieve sustainable and fully usable recycling of spent lithium-ion / polymer batteries, there is still a need for a process that enables improved recovery of lithium from sodium-containing sulfate solutions. Thus, the object of the present invention was to satisfy this need. SUMMARY OF THE INVENTION

[010] Within the scope of the present invention, it has been surprisingly found that the low separability of Li and Na ions from solutions containing sulfate can be overcome by a conversion of the corresponding hydroxides. BRIEF DESCRIPTION OF THE DRAWINGS

[011] Figure 1 shows schematically the concept of the process according to the invention.

[012] Figure 2a shows schematically how solution A is obtained from a suspension Y.

[013] Figure 2b shows how solution X can be further treated with H2SO4 to obtain the transition metal in the form of its sulfate.

[014] Figure 3 shows the schematic procedure of the process according to the invention. DETAILED DESCRIPTION OF PREFERRED MODALITIES

[015] Therefore, the present invention primarily relates to a process for the separation of Na and Li ions, in which an aqueous solution A containing Na2SO4 and Li2SO4 is subjected to electrolysis to obtain a solution B, and the resulting solution B is treated with a carbonate source to form Li2CO3. Experts are aware of the fact that the compounds Na2SO4, Li2SO4, Na2CO3, Li2CO3 and all other salts are in the form of their ions. Petition 870250079841, dated 05 / 09 / 2025, page 11 / 72 4 / 8 in a solution. Therefore, unless otherwise indicated, they are used interchangeably with the corresponding ions, and explicit mention of them is omitted.

[016] Surprisingly, it was found that the greater differences in solubility between U2CO3 and Na2CO3 compared to the solubilities of Na2SO4 and Li2SO4 can be used advantageously in order to achieve a more effective separation. Although the solubilities of Na2SO4 and Li2SO4 differ only by a factor of 2, Li2CO3 is distinctly more moderately soluble than Na2CO3, which allows for a more effective separation of the two metals. Therefore, in a preferred embodiment of the inventive process, Li2CO3 is separated to obtain a filtrate containing Na2CO3.

[017] Within the scope of the process according to the invention, a number of compounds can be employed as a carbonate source. Preferably, the carbonate source is selected from the group consisting of Na2CO3, CO2, NaHCO3, (NH4)2CO3, (NH4)HCO3, and mixtures thereof. The use of CO2 as a carbonate source has proven to be particularly advantageous and therefore preferable. It can be recovered, for example, from exhaust gases from other processes and thus directed towards sustainable use, so that CO2 emissions can be reduced.

[018] The process according to the invention provides that a solution of Na and Li sulfate salts is subjected to hydrolysis, whereby the sulfate salts are considered to be converted into the corresponding hydroxides, which can be separated more easily. In this respect, membrane electrolysis is preferred, particularly electrodialysis with bipolar membranes. Particularly preferred is multicompartment electrolysis with a cation exchange membrane and an anion exchange membrane.

[019] Within the scope of the process according to the invention, lithium is recovered as Li2CO3, which can be removed from the solution in the form of a solid in a subsequent step. Preferably, the Li2CO3 is separated by at least one process selected from the group consisting of Petition 870250079841, dated 05 / 09 / 2025, page 12 / 72 5 / 8 sedimentation, filtration and centrifugation. The separation may include a quick washing process, in which the washing liquors can be recycled to the general process at suitable points.

[020] The process according to the invention allows for an effective separation of Na and Li. If the degree of purity of the U2CO3 obtained is considered insufficient, the Li2CO3 can be subjected to additional purification steps. In a preferred embodiment, the Li2CO3 obtained is converted into soluble LiHCO3 in a subsequent step by treatment with CO2. High-purity Li2CO3 can be obtained from this solution by heating the solution containing LiHCO3. Therefore, an embodiment is preferred in which the solution containing LiHCO3 is heated to form Li2CO3. The purification step offers the advantage that the mother liquor obtained in the separation of Li2CO3 and the CO2 obtained in the formation of Li2CO3 and routed out of the reaction mixture can be recycled to the process to form a sustainable cycle.

[021] The starting solution A of the process according to the invention can be obtained by a number of processes such as those applied in recycling processes. The aqueous solution A containing sulfate is preferably obtained by treating a solution X, wherein said solution X includes Li2SO4 and at least one compound MSO4 in which M is a transition metal, preferably selected from the group consisting of Ni, Co, Mn, Al and mixtures thereof. For example, this treatment can be carried out using NaOH and optionally supplementary additions of H2SO4. It is considered that the metal M is converted into its hydroxide by treating solution X with NaOH to form Na2SO4 as a byproduct.Alternatively, the metal can be transferred to the organic phase initially by reactive extraction in the presence of an organic extraction agent, and subsequently extracted from the organic phase in the form of MSO4 back into the aqueous phase with sulfuric acid, and thus recycled to the subsequent cycle with added value.

[022] Preferably, within the scope of the process according to the invention, solution X is obtained by treating a suspension Y, which includes Petition 870250079841, dated 05 / 09 / 2025, page 13 / 72 6 / 8 at least one LIM₂ compound, with H₂SO₄ and a reducing agent, where M is a transition metal, preferably selected from the group consisting of Ni, Co, Mn, Al and their mixtures. Preferably, the reducing agent is selected from the group consisting of H₂O₂ and SO₂.

[023] The process according to the invention aims, in particular, at the recovery of Li from lithium-ion / polymer batteries. Therefore, an embodiment is preferred in which the suspension including LiMO2 is obtained from spent lithium-ion batteries and / or production rejects from their production.

[024] Thus, the process according to the invention provides a comprehensive recycling cycle that allows for the efficient recovery of lithium contained in lithium-ion / polymer batteries, and thus is a valuable contribution to the success of the pursued electromobility concept.

[025] Within the scope of the comprehensive recycling approach, the transition metal hydroxide obtained from the treatment of solution X can also be further processed, for example, for further use as an active cathode material in new batteries. Therefore, in a preferred embodiment of the process according to the invention, the treatment of solution X is carried out in such a way that a mixed transition metal hydroxide NixCoyMnz(OH)2 is further obtained by adjusting the stoichiometry of the transition metals and precipitation with NaOH. This stoichiometry adjustment can be carried out, for example, by selective separation or selective addition of one or more of the components of said mixed transition metal hydroxide. In this way, the desired Ni:Co:Mn ratio in the subsequent cathode material can be adjusted already in the mixed transition metal hydroxide.

[026] Within the scope of current lead times for nickel-enriched active cathode materials, stoichiometry adjustment by selective separation of one or more of the components of the mixed transition metal hydroxide is preferred. In a preferred embodiment, the Ni:Co:Mn ratio Petition 870250079841, dated 05 / 09 / 2025, p. 14 / 72 7 / 8 in mixed transition metal hydroxide is 1:1:1, alternatively preferably 8:1:1.

[027] In addition to recovering the materials used, especially precious metals, another aspect of a sustainable recycling strategy is the environmentally sound treatment of resources. Among other things, this means that, if possible, the reagents required for the recycling process are also recovered or recirculated. In the present process, this applies in particular to sulfuric acid, which is necessary to obtain solution X. Therefore, a preferred embodiment of the process according to the invention is one in which the sulfuric acid obtained by electrolysis is used at least in part to prepare solution X.

[028] The present invention further relates to a device for carrying out the process according to the invention. The device includes at least one electrolytic unit having at least one provision for introducing solution A and at least one drain for draining solution B.

[029] The present invention is further explained by means of the following Examples, which should in no way be understood as limiting the idea of ​​the invention.

[030] Figure 1 schematically shows the process concept according to the invention, whereby a solution A obtained during the recycling of lithium-ion / polymer batteries and containing Li2SO4 and Na2SO4 is subjected to electrolysis, whereby the sulfates are converted into the corresponding hydroxides, and the Li is separated in the form of Li2CO3 by treatment with CO2 as a carbonate source, while Na2CO3 remains in solution.

[031] Figure 2a shows schematically how solution A is obtained from a suspension Y obtained during the processing of lithium-ion / polymer batteries containing Li in the form of a lithium oxide / transition metal LiMO2. The lithium oxide / transition metal is converted to Li2SO4 and the corresponding transition metal sulfate MSO4 (solution X) by treatment with H2SO4 and a reducing agent, preferably H2O2 or SO2. The Petition 870250079841, dated 05 / 09 / 2025, page 15 / 72 8 / 8 Transition metal sulfate can be converted into the corresponding hydroxide M(OH)2 by treating solution X with NaOH and separating it, whereby a solution containing Na2SO4 and Li2SO4 is obtained and serves as starting solution A for the process according to the invention.

[032] According to the scheme shown in Figure 2b, solution X can be further treated with H2SO4 to obtain the transition metal in the form of its sulfate.

[033] Figure 3 shows the schematic procedure of the process according to the invention, in which a solution A of Li2SO4 and Na2SO4 is subjected to hydrolysis to obtain solution B, from which Li2CO3 can then be separated by treatment with a carbonate source. In this way, an effective separation of the two ions can be achieved. Petition 870250079841, dated 05 / 09 / 2025, page 16 / 72

Claims

1 / 2 CLAIMS 1. Process for the separation of Li and Na ions, characterized in that a solution A containing Na2SO4 and Li2SO4 is subjected to electrolysis to obtain a solution B, and the solution B obtained is treated with a carbonate source to form U2CO3.

2. Process according to claim 1, characterized in that the carbonate source is selected from the group consisting of Na2CO3, CO2, NaHCO3, (NH4)2CO3, (NH4)HCO3, and mixtures thereof.

3. A process according to at least one of the preceding claims, characterized in that said electrolysis is a multicompartment electrolysis with a cation exchange membrane and an anion exchange membrane, especially electrodialysis, preferably electrodialysis with bipolar membranes.

4. A process according to at least one of the preceding claims, characterized in that the Li2CO3 formed is separated by at least one process selected from the group of sedimentation, filtration and centrifugation.

5. A process according to at least one of the preceding claims, characterized in that the Li2CO3 obtained is converted into soluble LiHCO3 in a subsequent step by treatment with CO2.

6. Process according to at least one of the preceding claims, characterized in that aqueous solution A is obtained by treating solution X, wherein said solution X includes Li2SO4 and at least one MSO4 compound, in which M is a transition metal, preferably selected from the group consisting of Ni, Co, Mn, Al, and mixtures thereof.

7. Process according to claim 6, characterized in that solution X is obtained by treating a suspension Y, which includes at least one LiMO2 compound, with H2SO4 and a reducing agent, wherein M is a transition metal, preferably a metal selected from the Ni, Co, Mn, Al group, and mixtures thereof.

8. Process according to claim 7, characterized in that the compound including LiMO2 is obtained from spent lithium-ion / polymer batteries and / or production waste from battery production.

9. Process according to at least one of claims 6 to 8, characterized in that a mixed transition metal hydroxide NixMnyCoz(OH)2 is additionally obtained when solution X is treated, by adjusting the stoichiometry of the transition metal and precipitating with aqueous sodium hydroxide.

10. Process according to claim 9, characterized in that said adjustment of the transition metal stoichiometry is effected by selective separation or addition of one or more of the components of the mixed transition metal hydroxide.

11. Process according to at least one of the preceding claims, characterized in that the sulfuric acid obtained in the electrolysis is used at least in part to prepare solution X.

12. Device for carrying out the process according to at least one of the preceding claims, characterized by comprising an electrolytic unit provided with at least one provision for introducing solution A and at least one drain for draining solution B. Petition 870250079841, dated 05 / 09 / 2025, page 18 / 72

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