Recovering value metal from aqueous solutions

Abstract

The present disclosure relates to a process for recovering valuable materials from lithium ion battery material, and to a plant for recycling lithium ion battery materials, e.g., spent lithium ion batteries.

Description

[0001] Recovering value metal from aqueous solutions

[0002] The project leading to this application has received funding from Bundesministerium fur Wirtschaft und Klimaschutz and State of Brandenburg (DE; FKZ:16BZF101A / B); the applicant bears responsibility for all disclosures herein.

[0003] Field of the invention

[0004] The present disclosure relates to a process for recovering valuable materials from lithium ion battery material, and to a plant for recycling lithium ion battery materials, e.g., spent lithium ion batteries.

[0005] Background

[0006] Lithium ion battery materials are complex mixtures of various elements and compounds. For example, many lithium ion battery materials contain valuable metals such as lithium, aluminum, copper, nickel, cobalt, and / or manganese. It may be desirable to recover various elements and compounds from lithium ion battery materials. For example, it may be advantageous to recover lithium, aluminum, copper, nickel, cobalt, and / or manganese. Accordingly, there is a need for devices and processes for recycling lithium ion battery material.

[0007] WO 20231054621 A1 discloses a method for recovering valuable metals from waste lithium ion batteries comprising a dissolution step for dissolving an active material powder obtained by pre-treating the waste lithium-ion batteries in a mineral acid to obtain an acid solution; and a solvent extraction step for separating manganese, cobalt, and nickel, among metals contained in the active material powder, from the acid solution through solvent extraction to obtain a first lithium salt aqueous solution as a residual liquid of the solvent extraction.

[0008] WO 2020 / 124130 A1 discloses a method for the recovery of metals from a feed stream containing one or more value metals and lithium. The method comprises subjecting the feed stream to a sulfuric acid leach to form a slurry comprising a pregnant leach solution of soluble metal salts and a solid residue; separating the pregnant leach solution and the solid residue; subjecting the pregnant leach solution to one or more separate solvent extraction steps, wherein each solvent extraction step recovers one or more value metals from the pregnant leach solution, the remaining pregnant leach solution comprising lithium; and recovery of lithium from the pregnant leach solution.

[0009] KR 2021 0120669 A discloses a method for recovering manganese compounds from a waste positive electrode active material in the form of manganese sulfate, manganese carbonate and manganese oxide by leaching nickel (Ni), cobalt (Co) and lithium (Li), except manganese, selectively from waste positive electrode active material powder containing nickel (Ni), cobalt (Co), manganese (Mn) and lithium (Li), and subjecting manganese contained in the leached residue to an acid leaching process, solvent extraction process and a heat treatment process.

[0010] US 2022 / 320619 A1 discloses a method for recycling lithium batteries containing the steps: (a) digesting comminuted material, which contains comminuted components of electrodes of lithium batteries, using concentrated sulfuric acid at a digestion temperature (TA) of at least 100° C, so that waste gas and a digestion material are produced, (b) discharging the waste gas and (c) wet chemical extraction of at least one metallic component of the digestion material.

[0011] US 2022 / 205064 A1 discloses hydrometallurgical solvent extraction processes for recovering value metal ion species such as any of manganese, cobalt, nickel, and / or lithium from solutions derived from recycled electronics and / or batteries and containing mixed-metal ions by separating the value metal ions using selective stripping techniques.

[0012] It is an object of the present disclosure to provide an improved recycling plant for lithium ion battery materials and an improved recycling process for lithium ion battery materials.

[0013] Summary of the invention

[0014] The present disclosure provides a continuous process for recovering manganese carbonate from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. The process involves solvent extraction of the acidic aqueous solution with a suitable organic solvent to obtain a solvent phase comprising manganese cations; scrubbing and stripping the solvent phase comprising manganese cations with sulfuric acid to obtain an acidic aqueous solution comprising manganese cations, precipitating manganese carbonate from the acidic aqueous solution comprising manganese cations, and recovering manganese carbonate by solid / liquid separation.

[0015] The present disclosure also provides a production plant suitable for performing the continuous process of the present disclosure.

[0016] Brief description of the drawing

[0017] Fig. 1 is a schematic diagram of an exemplary production plant of the present disclosure.

[0018] Detailed description

[0019] The present disclosure provides a continuous process for recovering manganese carbonate from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations.

[0020] In some embodiments, the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations has been obtained by leaching lithium ion battery materials with sulfuric acid. Examples of suitable lithium ion battery materials for preparing the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations include black mass, cathode active materials, and mixed metal hydroxides (MHP). The acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations may additionally contain cations of other metals like copper, iron, aluminum, magnesium, calcium, and / or titanium; as well as anions like fluoride and / or phosphate.

[0021] In some embodiments of the process of the present disclosure, impurities are precipitated from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations prior to step a). The precipitation involves the addition of sodium carbonate. In other embodiments, precipitation involves the addition of calcium hydroxide or calcium carbonate instead of sodium carbonate. This offers the advantage of reducing sodium concentration in the mother liquor.

[0022] The impurities comprise one or more selected from iron, aluminum, magnesium, calcium, titanium, manganese, residual copper, fluoride, and phosphate. The precipitation involves the addition of a sodium carbonate solution to the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations, thereby adjusting the pH value of the solution to a value in the range of from 3.0 to 4.0. In some embodiments of the process, air is injected into the solution to oxidize any Fe(ll) present to Fe(lll). Iron, aluminum, and titanium precipitate from the solution as hydroxides and / or oxide-hydroxides and / or carbonates, fluorides and / or phosphates, and are removed from the mother liquor in a subsequent step by solid-liquid separation, e.g., filtration.

[0023] The mother liquor is further processed in a second precipitation step. The precipitation involves the addition of a sodium carbonate solution to the mother liquor obtained in the previous separation step, thereby adjusting the pH value of the solution to a value in the range of from 4.5 to 5.0. Iron, aluminum, and titanium precipitate from the solution as hydroxides and / or oxide-hydroxides and / or carbonates, fluorides and / or phosphates, and are removed from the mother liquor in a subsequent step by solid-liquid separation, e.g., filtration. The process of the present disclosure comprises a) adjusting the pH of the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations to be in the range of from 2 to 4, and removing manganese cations and any impurity cations of the group consisting of Ca, Cu, Zn, and Cd present in the solution by solvent extraction to obtain an aqueous solution depleted of manganese cations and impurity cations and a solvent comprising manganese cations and impurity cations, and scrubbing and stripping the solvent comprising manganese cations and impurity cations with sulfuric acid to obtain an acidic aqueous solution comprising manganese cations and impurity cations.

[0024] Solvent extraction is performed in step a) using an organic solvent suitable for extracting manganese cations from an aqueous solution. Examples of suitable organic solvents include bis(2-ethylhexyl)phosphate (D2EHPA). In some embodiments, the solvent used in step a) is a solution of 40 vol% bis(2- ethylhexyl)phosphate (D2EHPA) in dearomatized hydrocarbon fluid (Escaid™ 110).

[0025] The process also comprises b) adding carbonate anions to the acidic aqueous solution comprising manganese cations and impurity cations obtained in step a), adjusting the pH of the solution to be in the range of from 6.8 to 8.5, e.g., from 7.3 to 8.0, and precipitating manganese carbonate from the solution. In some embodiments of the process, sodium carbonate and / or lithium carbonate is added in step b).

[0026] In an embodiment of the process, the pH of the solution is b1 ) adjusted to be in the range of from 6.8 to 7.5 and a first precipitate containing manganese carbonate is precipitated from the solution and subsequently recovered by solid / liquid separation. Then, the pH of the solution obtained in step b1 ) is b2) adjusted to be in the range of from 7.5 to 8 and a second precipitate containing manganese carbonate is precipitated from the solution. The process further comprises c) recovering manganese carbonate from the mixture obtained in step b) by solid / liquid separation.

[0027] The process further comprises d) adjusting the pH of the aqueous solution depleted of manganese ions and impurity cations obtained in step a) to be in the range of from 3 to 6, and subsequently removing cobalt cations from the solution by solvent extraction to obtain an aqueous solution depleted of cobalt cations and a solvent comprising cobalt cations, and scrubbing and stripping the solvent comprising cobalt cations with sulfuric acid to obtain an acidic aqueous solution comprising cobalt cations. In some embodiments, the pH of the solution is adjusted in step d) to be in the range of from 4.3 to 5.8. In some embodiments, the process further comprises crystalizing cobalt sulfate from the acidic aqueous solution comprising cobalt cations obtained in step d).

[0028] Solvent extraction is performed in step d) using an organic solvent suitable for extracting cobalt cations from an aqueous solution. Examples of suitable organic solvents include phosphinic acid derivatives, e.g., bis-(2,4,4-trimethyl- pentyl) phosphinic acid (Cyanex® 272). In some embodiments, the solvent used in step d) is a solution of 20 vol% bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex® 272) in dearomatized hydrocarbon fluid (Escaid™ 110) containing 1 g / L butylhydroxytoluene (BHT).

[0029] The process further comprises e) adjusting the pH of the aqueous solution depleted of cobalt cations obtained in step d) to be in the range of from 5 to 7.5, e.g., from 6.1 to 7.1 , and subsequently removing nickel cations from the solution by solvent extraction to obtain an aqueous solution depleted of nickel cations and a solvent comprising nickel cations, and scrubbing and stripping the solvent comprising nickel cations with sulfuric acid to obtain an acidic aqueous solution comprising nickel cations. In some embodiments, the process further comprises crystalizing nickel sulfate from the acidic aqueous solution comprising nickel cations obtained in step e). Solvent extraction is performed in step e) using an organic solvent suitable for extracting nickel cations from an aqueous solution. Examples of suitable organic solvents include long chain carbonic acids, e.g., neodecanoic acid. In some embodiments, the solvent used in step e) is a solution of 30 vol% neodecanoic acid (Versatic™ 10) in dearomatized hydrocarbon fluid (Escaid™ 110) containing 1 g / L butylhydroxytoluene (BHT).

[0030] The process further comprises f) adjusting the pH of the aqueous solution depleted of nickel cations obtained in step e) to be in the range of from 10 to 12.5, e.g., from 10 to 10.5, and precipitating magnesium hydroxide from the solution.

[0031] The process further comprises g) removing solids from the mixture obtained in step f).

[0032] The process further comprises h) adjusting the pH of the aqueous solution obtained in step f) to be in the range of from 8 to 12, e.g., from 8 to 10, for instance, from 8 to 9, and subsequently removing lithium cations from the solution by solvent extraction to obtain an aqueous solution depleted of lithium cations and a solvent comprising lithium cations; and scrubbing and stripping the solvent comprising lithium cations with sulfuric acid to obtain an acidic aqueous solution comprising lithium cations. In some embodiments, the process further comprises crystalizing lithium sulfate from the acidic aqueous solution comprising lithium cations obtained in step h).

[0033] Solvent extraction is performed in step h) using an organic solvent suitable for extracting lithium cations from an aqueous solution. Examples of suitable organic solvents include organic solutions comprising an organic diluent, at least one phosphine oxide and at least one proton donating agent, as disclosed in WO 2013 / 065050 A1 . In some embodiments, the phosphine oxide corresponds to the general formula O=PRI R2R3, wherein each of Ri, R2and R3is independently selected from straight or branched C1-C10 alkyl, straight or branched C2-C10 alkenyl, straight or branched C2-C10 alkynyl, optionally substituted C5-C12 aryl, optionally substituted C4 -C12 heteroaryl; the at least one proton donating agent is selected from the group consisting of straight or branched C1-C10 alcohol, C1-C10 ketone, C1-C10 aldehyde, C3-C20 fatty acid, and any combination thereof; and the molar ratio between said phosphine oxide and an organic acid in said extracting organic solution is in the range of between about 5:1 to about 1 :5. In some embodiments, the solvent used in step h) is a solution of 27 vol% Cyanex® 936P in in dearomatized hydrocarbon fluid (Escaid™ 110).

[0034] The present disclosure also provides a production plant suitable for performing the process of the present disclosure. The production plant comprises a first solvent extraction (SX) unit configured to receive an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. The first SX unit comprises an extraction module and a scrubbing and stripping module. In the extraction module of the SX unit, an aqueous solution is extracted with an organic solvent, an aqueous phase and an organic phase being formed in the process. The organic phase is separated from the aqueous phase and transferred to the scrubbing and stripping module, where it is extracted with an aqueous acid. After scrubbing and stripping, the organic phase is cycled back to the extraction module. Suitable solvent extraction (SX) units are known in the art.

[0035] The production plant also comprises a first continuously stirred tank reactor (CSTR) configured to receive an aqueous effluent of the scrubbing and stripping module of the first SX unit. The first CSTR thus is located downstream of the first SX unit. The first CSTR comprises a dosing device for liquids, heating / cooling means, and gas injection means. Suitable continuously stirred tank reactors are known in the art.

[0036] The production plant further comprises at least one first solid / liquid separation device configured to receive an effluent of the first CSTR. The at least one first solid / liquid separation device thus is located downstream of the first CSTR. In some embodiments, the first solid / liquid separation device comprises a filter press.

[0037] The production plant of the present disclosure additionally comprises further SX units, further CSTRs, and further solid / liquid separation devices.

[0038] The production plant comprises a second solvent extraction (SX) unit configured to receive an aqueous effluent of the extraction module of the first SX unit. The second SX unit thus is located downstream of the first SX unit. The second SX unit comprises an extraction module and a scrubbing and stripping module. Suitable solvent extraction (SX) units are known in the art.

[0039] The production plant further comprises a third solvent extraction (SX) unit configured to receive an aqueous effluent of the extraction module of the second SX unit. The third SX unit thus is located downstream of the second SX unit. The third SX unit comprises an extraction module and a scrubbing and stripping module. Suitable solvent extraction (SX) units are known in the art.

[0040] The production plant further comprises a second continuously stirred tank reactor (CSTR) configured to receive an aqueous effluent of the extraction module of the third SX unit. The second CSTR thus is located downstream of the third SX unit. The second CSTR comprises a dosing device for liquids and heating / cooling means. Suitable continuously stirred tank reactors are known in the art.

[0041] The production plant further comprises at least one second solid / liquid separation device configured to receive an effluent of the second CSTR. The at least one second solid / liquid separation device thus is located downstream of the second CSTR. In some embodiments, the second solid / liquid separation device comprises a filter press.

[0042] The production plant further comprises a fourth solvent extraction (SX) unit configured to receive an aqueous effluent of the second solid / liquid separation device. The fourth SX unit thus is located downstream of the second solid / liquid separation device. The fourth SX unit comprises an extraction module and a scrubbing and stripping module. Suitable solvent extraction (SX) units are known in the art.

[0043] In further embodiments, the production plant additionally comprises crystallizers for producing a crystalline metal salt from aqueous solutions of the metal salt. Suitable crystallizers are known in the art.

[0044] In a particular embodiment, the production plant comprises three crystallizers. The production plant comprises a first crystallizer configured to receive an aqueous effluent of the scrubbing and stripping module of the second SX unit of the production plant and to produce crystals of a first metal salt, a second crystallizer configured to receive an aqueous effluent of the scrubbing and stripping module of the third SX unit of the production plant and to produce crystals of a second metal salt, and a third crystallizer configured to receive an aqueous effluent of the scrubbing and stripping module of the fourth SX unit of the production plant and to produce crystals of a third metal salt.

[0045] Detailed description of the drawing

[0046] A schematic diagram of an exemplary production plant of the present disclosure is shown in Fig. 1 .

[0047] The production plant comprises a first solvent extraction (SX) unit 10 which is configured to receive an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations 1000. The first SX unit 10 comprises an extraction module 11 and a scrubbing and stripping module 12. The acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations entering the first SX unit 10 is extracted with an organic solvent in the extraction module 11 . The extracted aqueous phase leaves the extraction module 11 as an aqueous effluent 1002. The loaded organic phase is transferred to the scrubbing and stripping module 12, where it is scrubbed and stripped of metal cations with sulfuric acid to produce an acidic aqueous solution comprising the metal cations from the organic phase. The organic phase is recycled to the extraction module 11 , and the acidic aqueous solution comprising the metal cations from the organic phase leaves the scrubbing and stripping module 12 as an aqueous effluent 1001.

[0048] The production plant further comprises a first continuously stirred tank reactor (CSTR) 50 which is configured to receive an aqueous effluent 1001 of the scrubbing and stripping module 12 of the first SX unit 10. The CSTR 50 comprises a dosing device for liquids, heating / cooling means, and gas injection means. In the CSTR 50, a solution comprising carbonate anions is added to precipitate manganese carbonate from the solution.

[0049] The production plant further comprises at least one first solid / liquid separation device 70 which is configured to receive an effluent 1003 of the first CSTR 50. In the at least one first solid / liquid separation device 70, manganese carbonate 1004 is recovered from the effluent of the first CSTR 50 by solid / liquid separation, e.g., filtration.

[0050] The production plant further comprises a second SX unit 20 which is configured to receive an aqueous effluent 1002 of the extraction module 11 of the first SX unit 10. The second SX unit 20 comprises an extraction module 21 and a scrubbing and stripping module 22. The aqueous effluent 1002 from the extraction module 11 of the first SX unit 10 is extracted with an organic solvent in the extraction module 21 . The extracted aqueous phase leaves the extraction module 21 as an aqueous effluent 2001. The loaded organic phase is transferred to the scrubbing and stripping module 22, where it is scrubbed and stripped of metal cations with sulfuric acid to produce an acidic aqueous solution comprising the metal cations from the organic phase. The organic phase is recycled to the extraction module 21 , and the acidic aqueous solution comprising the metal cations from the organic phase leaves the scrubbing and stripping module 22 as an aqueous effluent 2002. The production plant further comprises a third SX unit 30 which is configured to receive an aqueous effluent 2001 of the extraction module 21 of the second SX unit 20. The third SX unit comprises an extraction module 31 and a scrubbing and stripping module 32. The aqueous effluent 2001 from the extraction module 21 of the second SX unit 20 is extracted with an organic solvent in the extraction module 31. The extracted aqueous phase leaves the extraction module 31 as an aqueous effluent 3001. The loaded organic phase is transferred to the scrubbing and stripping module 32, where it is scrubbed and stripped of metal cations with sulfuric acid to produce an acidic aqueous solution comprising the metal cations from the organic phase. The organic phase is recycled to the extraction module 31 , and the acidic aqueous solution comprising the metal cations from the organic phase leaves the scrubbing and stripping module 32 as an aqueous effluent 3002.

[0051] The production plant further comprises a second CSTR 60 which is configured to receive an aqueous effluent 3001 of the extraction module 31 of the third SX unit 30. The second CSTR 60 comprises a dosing device for liquids and heating / cooling means. In the second CSTR 60, an alkaline solution is added to precipitate magnesium hydroxide from the solution.

[0052] The production plant further comprises at least one second solid / liquid separation device 80 which is configured to receive an effluent 3003 of the second CSTR 60. In the at least one second solid / liquid separation device 80, magnesium hydroxide3004 is recovered from the effluent 3003 of the second CSTR 60 by solid / liquid separation, e.g., filtration.

[0053] The production plant further comprises a fourth SX unit 40 which is configured to receive an aqueous effluent 3005 of the at least one second solid / liquid separation device 80. The fourth SX unit 40 comprises an extraction module 41 and a scrubbing and stripping module 42. The aqueous effluent 3005 from the at least one second solid / liquid separation device 80 is extracted with an organic solvent in the extraction module 41. The extracted aqueous phase leaves the extraction module 41 as an aqueous effluent 4001. The loaded organic phase is transferred to the scrubbing and stripping module 42, where it is scrubbed and stripped of metal cations with sulfuric acid to produce an acidic aqueous solution comprising the metal cations from the organic phase. The organic phase is recycled to the extraction module 41 , and the acidic aqueous solution comprising the metal cations from the organic phase leaves the scrubbing and stripping module 42 as an aqueous effluent 4002.

[0054] The production plant further comprises a first crystallizer 90 configured to receive an aqueous effluent 2002 of the scrubbing and stripping module 22 of the second SX unit 20 and to produce crystals of a first metal salt, e.g., cobalt sulfate.

[0055] The production plant further comprises a second crystallizer 100 configured to receive an aqueous effluent 3002 of the scrubbing and stripping module 32 of the third SX unit 30 and to produce crystals of a second metal salt, e.g., nickel sulfate.

[0056] The production plant further comprises a third crystallizer 110 configured to receive an aqueous effluent 4002 of the scrubbing and stripping module 42 of the fourth SX unit 40 and to produce crystals of a third metal salt, e.g., lithium sulfate.

[0057] Analytical methods

[0058] Residual moisture

[0059] Residual moisture was determined by a gravimetric method. The initial weight mtot of the sample was measured, then the sample was completely dried overnight in an oven at 70°C and 110 mbar pressure and subsequently the dry weight mdry was determined. Residual moisture was calculated as 1-(mdry / rntot)-

[0060] Particle Size Distribution

[0061] Particle size distribution was measured by dispersing a sample of the material in water comprising a non-ionic surfactant and measuring the dispersion in a laser diffraction particle size analyzer (Mastersizer® 3000, Malvern Panalytical GmbH, 34123 Kassel, Germany) coupled to an automated dispersion unit (Hydro MV, Malvern Panalytical GmbH, 34123 Kassel, Germany). The sample was dispersed in 120 ml water comprising 1-2 ml of a polyethylene glycol ether (0.5 wt.-% solution of Lutensol® XL 80, BASF SE), stirring at 3,500 rpm and using 2 min of ultrasound sonification.

[0062] Metal content

[0063] Elemental analysis of solids was performed using a combination of acid dissolution and alkaline-borate fusion digestion with analysis by inductively coupled plasma optical emission spectrometry (ICP-OES) on an inductively coupled plasma optical emission spectrometer (e.g., Agilent 5110 ICP-OES, Agilent Technologies Germany GmbH & Co. KG, 76337 Waldbronn, Germany).

[0064] An aliquot (e.g., about 0.2 g) of the sample material was weighed into a volumetric flask and dissolved under slight heating with 30 ml HCI. After cooling down, the insoluble residue was filtered out and incinerated together with the filter paper in a Pt crucible above an open flame. Subsequently, the residue was calcinated at about 600 °C in a muffle furnace and then mixed with 1.0 g of a K2CO3-Na2CO3 / Na2B4O7 flux mixture (4:1 ) and melted above an open flame until a clear melt was obtained. After cooling down, the melt cake was dissolved in deionized (DI) water under slight heating and 12 ml of HCI were added. Finally, the solution was joined to the initial filtered solution in the volumetric flask and topped up to its final volume with DI water. Each sample was prepared in triplicate. A blank sample was prepared in an analogous manner.

[0065] The digestion solution was analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES), using external calibration. For some samples, the digestion solution may be diluted before analysis, e.g., adapted to the concentration and calibration range of the respective analyte. Examples

[0066] Unless indicated otherwise, all percentages given refer to weight percent (wt.%)

[0067] Example 1

[0068] 200 g of a solution with a pH of 2 (feed composition 1 ) containing Mn, Ca and Zn in the ratio of 48.3 to 1.7 to 1 by weight and other trace elements typically found in battery waste streams (e.g. Ni and Co) was heated to 60°C. The mixture was subsequently treated with a Na2CO3-solution until a pH value of 8.8 was reached, during which precipitation of a colorless to pale pinkish solid occurred. After a total reaction time of 130 min, the suspension was filtered off and the solid was washed. A moist solid residue and filtrate could be obtained with a yield of 8.3 and 227.5 g, respectively. Residual moisture and particle size distribution of the solid were determined to be 27.5% and D(50) = 15.7 pm, respectively. The Mn:Ca:Zn-ratio in the solid remained mostly unchanged (47.8 to 1.78 to 1 ), meaning no reduction of one element over the other could be observed. The final Mn yield amounted to 100% (2.8 g). The solid contained 1.71 % of the Na introduced through Na2CO3.

[0069] Example 2

[0070] 200.7 g of a solution with a pH of 2 (feed composition 1 ) containing Mn, Ca and Zn in the ratio of 48.3 to 1.7 to 1 by weight and other trace elements typically found in battery waste streams (e.g. Ni and Co) was heated to 60°C. The mixture was subsequently treated with a Na2CO3-solution until a pH value of 7.8 was reached, during which precipitation of a colorless to pale pinkish solid occurred. After a total reaction time of 130 min, the suspension was filtered off and the solid was washed. A moist solid residue and filtrate could be obtained with a yield of 8.0 and 251 .1 g, respectively. Residual moisture and particle size distribution of the solid were determined to be 27.5% and D(50) = 13.7 pm, respectively. A Mn:Ca:Zn-ratio of 45.3:1.2:1 in the final product shows that the Ca-content could be reduced by 28.5%. The final Mn-yield amounted to 100% (2.7 g). The solid contained 1.24% of the Na introduced through Na2CO3. Example 3

[0071] 200 g of a solution with a pH of 2 (feed composition 1 ) containing Mn, Ca and Zn in the ratio of 48.3 to 1.7 to 1 by weight and other trace elements typically found in battery waste streams (e.g. Ni and Co) was heated to 60°C. The mixture was subsequently treated with a Na2CO3-solution until a pH value of 7.3 was reached, during which precipitation of a colorless to pale pinkish solid occurred. After a total reaction time of 80 min, the suspension was filtered off and the solid was washed. A moist solid residue and filtrate could be obtained with a yield of 6.6 and 181.2 g, respectively. Residual moisture and particle size distribution of the solid were determined to be 20.00% and D(50) = 18.0 pm, respectively. A Mn:Ca:Zn-ratio of 93.5:1 :2.4 in the final product shows that the Ca-content could be reduced by 74.1 %. The final Mn-yield amounted to 87.9% (2.4 g). The solid contained 0.93% of the Na introduced through Na2CO3.

[0072] Example 4

[0073] 600 g of a solution with a pH of 1 .7 (feed composition 2) containing Mn, Ca and Zn in the ratio of 46 to 1.5 to 1 by weight and other trace elements typically found in battery waste streams (e.g. Ni and Co) was heated to 43°C. The mixture was subsequently treated with a Na2CO3-solution until a pH value of 5.7 was reached, during which precipitation of a colorless to pale pinkish solid occurred. After a total reaction time of 80 min, the suspension was filtered off and the solid was washed. A moist solid residue and filtrate could be obtained with a yield of 18.8 and 676 g, respectively. Residual moisture and particle size distribution of the solid were determined to be 20.00% and D(50) = 18.0 pm, respectively. A Mn:Ca:Zn-ratio of 82.7:1 :2.3 in the final product shows that the Ca-content could be reduced by 72.6%. The final Mn-yield amounted to 76.1 % (5.9 g). The solid contained 1.26% of the Na introduced through Na2CO3.

[0074] Example 5

[0075] 78.0 kg of a solution with a pH of 1.7 (feed composition 2) containing Mn, Ca and Zn in the ratio of 46 to 1 .5 to 1 by weight and other trace elements typically found in battery waste streams (e.g. Ni and Co) was heated to 43°C. The mixture was subsequently treated with a Na2CO3-solution until a pH value of 7.3 was reached, during which precipitation of a colorless to pale pinkish solid occurred. The reaction was performed in a continuous setup and after filtration 2.65 kg of a moist solid residue and 95.1 kg filtrate could be obtained in total. Residual moisture and particle size distribution of the solid were determined to be 16.00% and D(50) = 25.0 pm, respectively. A Mn:Ca:Zn-ratio of 50:1 :1.2 in the final product shows that the Ca-content could be reduced by 51 %. The final Mn-yield amounted to 88.0% (981 g).

[0076] The metal content of the feed solutions, as determined by ICP-OES, are summarized in Table 1. The results of the elemental analyses of the solids obtained in Examples 1-5, as determined by ICP-OES, are given in Table 2.

[0077] Table 1 Metal content of the feed solutions (determined by ICP-OES)

[0078] Feed Mn Ca Zn Ni Co

[0079] 1 1.40% 0.05% 0.029% 0.005% 0.004%

[0080] 2 1.38% 0.046% 0.030% 0.006% 0.004%

[0081] Table 2 Metal content of the solids obtained in Examples 1-5 (determined by ICP-OES)

[0082] Solid Mn Ca Zn Ni Co Na

[0083] I 42% 1.60% 0.90% 0.14% 0.12% 0.79%

[0084] II 43% 1.10% 0.95% 0.13% 0.12% 0.48%

[0085] III 43% 0.46% 1.10% 0.08% 0.12% 0.34%

[0086] IV 43% 0.52% 1.20% 0.05% 0.09% 0.57%

[0087] V 42% 0.86% 1.00 0.06% 0.10% 0.64%

[0088] Example 6

[0089] 63.0 kg of a solution containing Mn, Ca, Zn, Mg, Ni, Co, and Li was heated to 45°C. The mixture was subsequently treated with a Na2CO3-solution until a pH value of 7.5 was reached, during which precipitation of a solid occurred. In total, 18 kg of 17 wt.% sodium carbonate solution were added. The reaction was performed in a continuous setup and after filtration 2.1 kg of a moist solid residue could be obtained from 81 kg slurry in total. Residual moisture of the solid was determined to be 11 %.

[0090] The metal content of the feed solution, the solids, and the filtrate, respectively, as determined by ICP-OES, are summarized in Table 3.

[0091] Table 3 Metal content of feed, solids, and filtrate (determined by ICP-OES)

[0092] Mn Ca Zn Mg Ni Co Li

[0093] Feed 0.70% 0.004% < 0.001 % 0.007% 0.01 % 0.12% 0.03%

[0094] Solids 29.90% 0.18% 0.005% 0.12% 0.44% 5.90% 0.18%

[0095] Filtrate < 0.001 % < 0.001 % < 0.001 % 0.004% 0.002% 0.001 % 0.03%

[0096] Determination of Metal Yields

[0097] Metal yields were determined using elemental contents determined by ICP- OES. If not stated otherwise, metal yields were determined using the elemental content determined in the dry solids

[0098] The following formulas were utilized: m Epc)=EICP-FC * n(F C) ( 2 ) wherein

[0099] E denotes a given element,

[0100] FC denotes the dry solid,

[0101] EICP-FC is the determined percentage-based content in the dry solid, m(FC) is the mass of the dry solid, m(EFc) is the weight content of the element in the dry solid, m(EMax) is the total amount of an element found in all product fractions, and

[0102] MYEis the metal yield of the respective element.

[0103] List of reference numerals

[0104] 10 First SX unit

[0105] 11 Extraction module of first SX unit

[0106] 12 Scrubbing and stripping module of first SX unit

[0107] 20 Second SX unit

[0108] 21 Extraction module of second SX unit

[0109] 22 Scrubbing and stripping module of second SX unit

[0110] 30 Third SX unit

[0111] 31 Extraction module of third SX unit

[0112] 32 Scrubbing and stripping module of third SX unit

[0113] 40 Fourth SX unit

[0114] 41 Extraction module of fourth SX unit

[0115] 42 Scrubbing and stripping module of fourth SX unit

[0116] 50 First CSTR

[0117] 60 Second CSTR

[0118] 70 First solid / liquid separation unit

[0119] 80 Second solid / liquid separation unit

[0120] 90 First crystallizer

[0121] 100 Second crystallizer

[0122] 110 Third crystallizer

[0123] 1000 Acidic aqueous solution comprising Ni, Co, Mn, and Li cations

[0124] 1001 Aqueous effluent of scrubbing and stripping module of first SX unit

[0125] 1002 Aqueous effluent of extraction module of first SX unit

[0126] 1003 Effluent of first CSTR

[0127] 1004 Solids (manganese carbonate)

[0128] 1005 Aqueous effluent of first solid / liquid separation unit

[0129] 2001 Aqueous effluent of scrubbing and stripping module of second SX unit 2002 Aqueous effluent of extraction module of second SX unit

[0130] 3001 Aqueous effluent of scrubbing and stripping module of third SX unit

[0131] 3002 Aqueous effluent of extraction module of third SX unit

[0132] 3003 Effluent of second CSTR 3004 Solids (magnesium hydroxide)

[0133] 3005 Aqueous effluent of second solid / liquid separation unit

[0134] 4001 Aqueous effluent of scrubbing and stripping module of fourth SX unit

[0135] 4002 Aqueous effluent of extraction module of fourth SX unit

Claims

Claims1 . A continuous process for recovering manganese carbonate from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations, the process comprising a) adjusting the pH of the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations to be in the range of from 2 to 4, and removing manganese cations and any impurity cations of the group consisting of Ca, Cu, Zn, and Cd present in the solution by solvent extraction to obtain an aqueous solution depleted of manganese cations and impurity cations and a solvent comprising manganese cations and impurity cations, and scrubbing and stripping the solvent comprising manganese cations and impurity cations with sulfuric acid to obtain an acidic aqueous solution comprising manganese cations and impurity cations, b) adding carbonate anions to the acidic aqueous solution comprising manganese cations and impurity cations obtained in step a), adjusting the pH of the solution to be in the range of from 6.8 to 8.5, and precipitating manganese carbonate from the solution, c) recovering manganese carbonate from the mixture obtained in step b) by solid / liquid separation, d) adjusting the pH of the aqueous solution depleted of manganese ions and impurity cations obtained in step a) to be in the range of from 3 to 6, and subsequently removing cobalt cations from the solution by solvent extraction to obtain an aqueous solutiondepleted of cobalt cations and a solvent comprising cobalt cations, and scrubbing and stripping the solvent comprising cobalt cations with sulfuric acid to obtain an acidic aqueous solution comprising cobalt cations, e) adjusting the pH of the aqueous solution depleted of cobalt cations obtained in step d) to be in the range of from 5 to 7.5, and subsequently removing nickel cations from the solution by solvent extraction to obtain an aqueous solution depleted of nickel cations and a solvent comprising nickel cations, and scrubbing and stripping the solvent comprising nickel cations with sulfuric acid to obtain an acidic aqueous solution comprising nickel cations, f) adjusting the pH of the aqueous solution depleted of nickel cations obtained in step e) to be in the range of from 10 to 12.5, and precipitating magnesium hydroxide from the solution, g) removing solids from the mixture obtained in step f), h) adjusting the pH of the aqueous solution obtained in step f) to be in the range of from 8 to 12, and subsequently removing lithium cations from the solution by solvent extraction to obtain an aqueous solution depleted of lithium cations and a solvent comprising lithium cations; and scrubbing and stripping the solvent comprising lithium cations with sulfuric acid to obtain an acidic aqueous solution comprising lithium cations.

2. The process of claim 1 , further comprising d1 ) crystalizing cobalt sulfate from the acidic aqueous solution comprising cobalt cations obtained in step d).

3. The process of claim 1 or 2, further comprising e1 ) crystalizing nickel sulfate from the acidic aqueous solution comprising nickel cations obtained in step e).

4. The process of any one of claims 1 to 3, further comprising f1 ) crystalizing lithium sulfate from the acidic aqueous solution comprising lithium cations obtained in step h).

5. The process of any one of claims 1 to 4, wherein sodium carbonate and / or lithium carbonate is added in step b).

6. The process of any one of claims 1 to 5, wherein the solvent used in step a) is a solution of 40 vol% bis(2-ethylhexyl)phosphate in dearomatized hydrocarbon fluid.

7. The process of any one of claims 1 to 6, wherein the solvent used in step d) is a solution of 20 vol% bis-(2,4,4-trimethylpentyl) phosphinic acid in dearomatized hydrocarbon fluid containing 1 g / L butylhydroxytoluene.

8. The process of any one of claims 1 to 7, wherein the solvent used in step e) is a solution of 30 vol% neodecanoic acid in dearomatized hydrocarbon fluid containing 1 g / L butylhydroxytoluene .

9. The process of any one of claims 1 to 8, wherein the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations has been obtained by leaching lithium ion battery materials with sulfuric acid.

10. The process of claim 9, wherein the lithium ion battery materials are selected from the group consisting of black mass, cathode active materials, and mixed metal hydroxide precipitates.

11. The process of any one of claims 1 to 10, wherein impurities comprising one or more selected from iron, aluminum, magnesium, calcium, titanium, manganese, copper, fluoride, and phosphate are precipitated from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations prior to step a) by addition of sodium carbonate and / or calcium hydroxide and / or calcium carbonate to the acidic aqueous solutioncomprising nickel, cobalt, manganese, and lithium cations, thereby adjusting the pH value of the solution to a value in the range of from 3.0 to 4.0, and removing the precipitate from the mother liquor in a subsequent step by solid-liquid separation.

12. The process of claim 11 , wherein the mother liquor is further processed in a second precipitation step involving the addition of a sodium carbonate solution to the mother liquor obtained in the previous separation step, thereby adjusting the pH value of the solution to a value in the range of from 4.5 to 5.0, and removing the precipitate from the mother liquor in a subsequent step by solid-liquid separation.

13. A production plant comprising1 ) a first solvent extraction (SX) unit (10) configured to receive an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations, the first SX unit (10) comprising i. an extraction module (11 ), ii. a scrubbing and stripping module (12),2) a first continuous stirred-tank reactor (CSTR) (50) configured to receive an aqueous effluent of the scrubbing and stripping module (12) of the first SX unit (10), the CSTR (50) comprising i. a dosing device for liquids, ii. heating / cooling means, iii. gas injection means,3) at least one first solid / liquid separation device (70) configured to receive an effluent of the first CSTR (50),4) a second solvent extraction (SX) unit (20) configured to receive an aqueous effluent of the extraction module (11 ) of the first SX unit (10), the second SX unit (20) comprising i. an extraction module (21 ), ii. a scrubbing and stripping module (22),5) a third solvent extraction (SX) unit (30) configured to receive an aqueous effluent of the extraction module (21 ) of the second SX unit (20), the third SX unit comprising i. an extraction module (31 ), ii. a scrubbing and stripping module (32),6) a second continuous stirred-tank reactor (CSTR) (60) configured to receive an aqueous effluent of the extraction module (31 ) of the third SX unit (30), the second CSTR (60) comprising i. a dosing device for liquids, ii. heating / cooling means,7) at least one second solid / liquid separation device (80) configured to receive an effluent of the second CSTR (60),8) a fourth solvent extraction (SX) unit (40) configured to receive an aqueous effluent of the second solid / liquid separation device (80), the fourth SX unit (40) comprising i. an extraction module (41 ), ii. a scrubbing and stripping module (42).

14. The production plant of claim 13, additionally comprising9) a first crystallizer (90) configured to receive an aqueous effluent of the scrubbing and stripping module (22) of the second SX unit (20) and to produce crystals of a first metal salt,10) a second crystallizer (100) configured to receive an aqueous effluent of the scrubbing and stripping module (32) of the third SX unit (30) and to produce crystals of a second metal salt,11 ) a third crystallizer (110) configured to receive an aqueous effluent of the scrubbing and stripping module (42) of the fourth SX unit (40) and to produce crystals of a third metal salt.

15. The production plant of claim 13 or 14, wherein the first solid / liquid separation device (70) comprises a filter press.

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