Continuous process and production plant for recovering metals from acidic aqueous solutions

Abstract

The present disclosure relates to a continuous process and a production plant for recovering metal salts from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations.

Description

[0001] Continuous process and production plant for recovering metals from acidic 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 continuous process and a production plant for recovering metal salts from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations.

[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 materials.

[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] 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.

[0010] 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.

[0011] Summary of the invention

[0012] The present disclosure provides a continuous process for recovering metal salts from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. The process involves removing impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution by precipitation, followed by solvent extraction of manganese cations and any impurity cations of the group consisting of Ca, Cu, Zn, and Cd from the solution, recovering cobalt cations from the aqueous solution depleted of manganese cations and impurity cations by solvent extraction, recovering nickel cations from the aqueous solution depleted of cobalt cations by solvent extraction, precipitating magnesium hydroxide from the aqueous solution depleted of nickel cations and recovering solid magnesium hydroxide, and recovering lithium cations from the aqueous solution depleted of magnesium cations by solvent extraction.

[0013] The present disclosure also provides a production plant suitable for performing the continuous process of the present disclosure.

[0014] Brief description of the drawings

[0015] Fig. 1 is a schematic diagram of an exemplary production plant of the present disclosure.

[0016] Fig. 2 is a schematic diagram of a section of another exemplary production plant of the present disclosure.

[0017] Detailed description

[0018] The present disclosure provides a continuous process for recovering metal salts from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. 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 comprising phosphorus, fluoride, silicon, and or aluminum.

[0019] The continuous process of the present disclosure comprises the steps of a) optionally, adjusting the pH value of the solution to a value in the range of from 1.5 to 2.5 and recovering copper from the solution by solvent extraction or by precipitation of copper sulfide, followed by solid / liquid separation, b) adjusting the pH of the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations to be in the range of from 3.0 to 4.0 by addition of sodium carbonate, and subsequently precipitating impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution from the solution, c) removing solids from the mixture obtained in step b), d) adjusting the pH of the acidic aqueous solution obtained in step c) to be in the range of from 4.5 to 5.0 by addition of sodium carbonate, and subsequently precipitating impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution from the solution, e) removing solids from the mixture obtained in step d), f) adjusting the pH of the acidic aqueous solution obtained in step e) to be in the range of from 2 to 4, and subsequently removing manganese cations and any residual impurity cations of the group consisting of Ca, Cu, Zn, and Cd cations 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, g) adjusting the pH of the aqueous solution depleted of manganese cations and impurity cations obtained in step f) 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, h) adjusting the pH of the aqueous solution depleted of cobalt cations obtained in step g) 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, i) adding sodium hydroxide to the aqueous solution depleted of nickel cations obtained in step h), adjusting the pH of to be in the range of from 10 to 12.5, and precipitating magnesium hydroxide from the solution, j) removing solids from the mixture obtained in step i), k) adjusting the pH of the aqueous solution obtained in step j) 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.

[0020] Solvent extraction (SX) is a useful method for separating and purifying metal cations from an aqueous solution or leachate. This can be difficult when purifying metal cations present in a hydrated form in an aqueous solution, since it is difficult to move the cations to an organic solvent layer having a low polarity. In order to move hydrated metal cations to the organic phase, the metal cations should be in a form of an uncharged complex and the metal cations should be able to remove water molecules from the hydrated complex.

[0021] A solvent extracting agent allows the metal cations to form a non-charged complex and remove water molecules. The extraction efficiency depends on, e.g., the type of solvent extracting agent, the equilibrium pH, and the metal cations in the aqueous solution. The extraction efficiency may also be affected by, e.g., the concentration of the solvent extracting agent, the ratio of the solvent extracting agent to the aqueous solution, and the composition and concentration of the stripping solution.

[0022] In some embodiments, solvent extraction is a two-step process (or even a three-step process if impurities need to be scrubbed before the stripping). The scrubbing step (step 2), if necessary, is carried out in-between the extraction of the target species into the organic phase (step 1 ) and the stripping (step 3).

[0023] In a first step, a solvent extracting agent (a non-polar weak acid) is dissolved in an organic liquid (diluent), such as kerosene. This mixture forms the extracting agent solution. This solution is brought into contact / mixed with the acidic aqueous solution, from which the extracting agent extracts metal cations. Depending on the extracting agent selected, different metal cations can be extracted from the acidic aqueous solution.

[0024] In a second optional step, impurities are removed from the organic phase (the extracting agent solution) by scrubbing. In some embodiments of the process, scrubbing is conducted by treatment with fresh scrub solution (aqueous phase), which contains chemicals to remove impurity metals from the organic phase, selectively reversing the reaction. The spent scrub solution is normally combined with the SX Feed. The scrubbed organic phase containing the metal of interest is separated from the aqueous phase, and is advanced to stripping. In some embodiments, diluted sulfuric acid is used for scrubbing. In some embodiments, a solution comprising the same metal cations as those extracted from the acidic aqueous solution is used for scrubbing. In some embodiments, the aqueous solution comprising metal cations obtained after stripping of the organic phase, i.e. , the product of the solvent extraction procedure, is used for scrubbing.

[0025] Subsequently, the extracting agent solution, which now comprises metal cations, is brought into contact with an acid solution (strong acid), which causes the metal cations to be replaced by H+. In return, the metal cations transfer into the acidic aqueous solution. This solution is then called loaded stripping solution. The process of transferring the metal cations back into an aqueous phase is called stripping.

[0026] In an optional first step a) of the process of the present disclosure, copper is recovered by a first solvent extraction from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. In some embodiments of the process, the solvent extracting agent is LIX984N, a 1 :1 mixture of 5-nonyl salicylaldoxime and 2-hydroxy-5-nonyl acetophenone.

[0027] In some embodiments, the first solvent extraction comprises

[0028] • adding an alkaline solution to the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations to adjust the pH value of the solution to a value in the range of from 1 .5 to 2.5;

[0029] • adding a solvent extracting agent to the acidic aqueous solution,

[0030] • homogenizing the mixture of acidic aqueous solution and solvent extracting agent,

[0031] • allowing the mixture to separate into a layer of an acidic aqueous solution depleted of Cu and a layer of solvent extracting agent comprising Cu,

[0032] • separating the layer of solvent extracting agent comprising Cu from the layer of acidic aqueous solution depleted of Cu,

[0033] • mixing the separated solvent extracting agent comprising Cu with a second aqueous acidic solution,

[0034] • homogenizing the mixture,

[0035] • allowing the mixture to separate into a layer of a second aqueous solution comprising copper and a layer of solvent extracting agent, and

[0036] • separating the aqueous solution comprising Cu from the layer of solvent extracting agent.

[0037] In some embodiments, the first solvent extraction is a two-step process (or even a three-step process if impurities need to be scrubbed before the stripping). The optional step of scrubbing (step 2), if necessary, is carried out in-between the extraction of the target species into the organic phase (step 1 ) and the stripping (step 3).

[0038] In a first step, a solvent extracting agent (a non-polar weak acid) is dissolved in an organic liquid (diluent), such as kerosene. This mixture forms the extracting agent solution. This solution is brought into contact / mixed with the acidic aqueous solution, from which the extracting agent selectively extracts copper cations.

[0039] In a second optional step, impurities are removed from the organic phase (the extracting agent solution) by scrubbing.

[0040] Subsequently, the extracting agent solution, which now comprises copper cations, is brought into contact with an acid solution (strong acid), which causes the copper cations to be replaced by H+. In return, the copper cations transfer into the acidic aqueous solution. This solution is then called loaded stripping solution. The process of transferring the copper cations back into an aqueous phase is called stripping.

[0041] In some embodiments, copper is recovered by precipitation followed by solid / liquid separation. In some embodiments, the copper ions are removed by precipitation of copper sulfide. To precipitate copper sulfide, sulfide, hydrogen sulfide, or thiosulfate ions are added to the solution. In some embodiments, Na2SO3 is added to the solution to precipitate copper sulfide. The precipitate is separated from the aqueous solution depleted of copper cations by solid / liquid separation, for instance, by filtration.

[0042] The acidic aqueous solution depleted of Cu obtained after the first solvent extraction, or after precipitation of copper sulfide, followed by solid / liquid separation, is further processed in step b).

[0043] In step b) of the process of the present disclosure, impurities are precipitated from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. The precipitation involves the addition of sodium carbonate or calcium carbonate. Impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution are precipitated from the solution as salts. The impurities comprise one or more selected from iron, aluminum, magnesium, calcium, titanium, manganese, residual copper, fluoride, silicate, and phosphate. The precipitation involves the addition of a sodium carbonate solution or calcium carbonate 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, magnesium, titanium, and copper 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 c) by solid-liquid separation, e.g., filtration.

[0044] The mother liquor is further processed in a second precipitation step d). The precipitation involves the addition of a sodium carbonate solution or calcium carbonate to the mother liquor obtained in step c), thereby adjusting the pH value of the solution to a value in the range of from 4.5 to 5.0. Impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution are precipitated from the solution. Iron, aluminum, magnesium, titanium, and copper 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 e) by solid-liquid separation, e.g., filtration. In some embodiments of the process, some manganese also is precipitated as manganese carbonate. As the precipitate obtained in step e) may contain significant amounts of value metals, in particular, nickel, it can be recycled into a leaching step and used for generating an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations.

[0045] Using the two-stage precipitation and separation process of steps b) through e) maximizes precipitation of Al, Fe, F and thus the removal of impurities from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations, and it minimizes co-precipitation of value metals, and thus minimizes losses of nickel, cobalt, manganese, and lithium. The process further comprises f) adjusting the pH of the mother liquor obtained in step e) to be in the range of from 2 to 4, and subsequently removing manganese cations and any residual 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.

[0046] The process further comprises g) adjusting the pH of the aqueous solution depleted of manganese cations and impurity cations obtained in step f) 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 of the process, diluted loaded strip liquor is used for scrubbing.

[0047] The process further comprises h) adjusting the pH of the aqueous solution depleted of cobalt cations obtained in step g) 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. In some embodiments of the process, diluted loaded strip liquor is used for scrubbing.

[0048] The process further comprises i) adding sodium hydroxide to the aqueous solution depleted of nickel cations obtained in step h), adjusting the pH of to be in the range of from 10 to 12.5, and precipitating magnesium hydroxide from the solution. This step is essential for the subsequent recovery of lithium cations by solvent extraction. It has been found that magnesium cations hamper the phase separation of the organic phase from the aqueous phase in solvent extraction of lithium-containing solutions. Without prior removal of magnesium cations from the solution, solvent extraction of lithium cations does not work properly.

[0049] The process further comprises j) removing solids from the mixture obtained in step i).

[0050] The process further comprises k) adjusting the pH of the aqueous solution obtained in step j) 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. As the aqueous solution obtained in step j) also contains high concentrations of sodium cations, recovery of lithium cations from the solution by solvent extraction offers advantages over the precipitation of lithium salts like lithium carbonate, as contamination of the acidic aqueous solution comprising lithium cations by sodium cations, and consequently, the sodium content of lithium salts recovered from the acidic aqueous solution comprising lithium cations is minimized.

[0051] In some embodiments, the process further comprises I) adjusting the pH of the acidic aqueous solution comprising manganese cations and impurity cations obtained in step f) to be in the range of from 6.8 to 8.5 (for instance, from 7.3 to 8) by addition of sodium carbonate, and precipitating manganese carbonate from the solution. In other embodiments, the process further comprises I) adjusting the pH of the acidic aqueous solution comprising manganese cations and impurity cations obtained in step f) to be in the range of from 6.8 to 8.5 (for instance, from 7.3 to 8) by addition of sodium hydroxide, and precipitating manganese hydroxide from the solution. Step I) is followed by m) removing solids from the mixture obtained in step I). In some embodiments, the process further comprises n) adding sodium hydroxide to the aqueous solution obtained in step m), adjusting the pH of the solution to be in the range of from 10 to 12.5, and precipitating metal hydroxides from the solution.

[0052] In some embodiments, the process further comprises o) removing solids from the mixture obtained in step n).

[0053] In some embodiments, the process further comprises p) crystallizing cobalt sulfate from the acidic aqueous solution comprising cobalt cations obtained in step g).

[0054] In some embodiments, the process further comprises q) crystallizing nickel sulfate from the acidic aqueous solution comprising cobalt cations obtained in step h).

[0055] In some embodiments, the process further comprises r) crystallizing lithium sulfate from the acidic aqueous solution comprising cobalt cations obtained in step k).

[0056] In some embodiments, the process additionally comprises s) adjusting the pH of the aqueous solution obtained in step e) to be in the range of from 7 to 8.5, and precipitating a mixed metal hydroxide and / or carbonate (MHP) from the solution, t) performing a solid / liquid separation of the mixture obtained in step s) to obtain solid MHP and a mother liquor, u) dissolving the solid MHP in sulfuric acid, v) removing residual solids from the solution obtained in step u), w) feeding the solution obtained in step v) into step f), and x) feeding the mother liquor obtained in step t) into step i). The mother liquor obtained in step t) comprises lithium, sodium, and magnesium cations which can be recovered from the mother liquor.

[0057] In some embodiments, the process additionally comprises y) performing solvent extraction of the mother liquor obtained after crystallizing nickel sulfate in step q) to obtain an aqueous solution depleted of nickel cations and a solvent comprising nickel cations; and feeding the solvent comprising nickel cations into step g).

[0058] Solvent extraction is performed in step f) using an organic solvent suitable for extracting manganese cations and impurity cations of the group consisting of Ca, Cu, Zn, and Cd from an aqueous solution. In some embodiments, the solvent used in step a) is a solution of 40 vol% bis(2-ethylhexyl)phosphate (D2EHPA) in dearomatized hydrocarbon fluid, e.g., kerosene such as Exxsol™ D80 or Escaid™ 110.

[0059] Solvent extraction is performed in step g) 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 b) 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).

[0060] Solvent extraction is performed in step h) using an organic solvent suitable for extracting nickel cations from an aqueous solution. In some embodiments, the organic solvent used in step c) is a solution of 30 vol% neodecanoic acid (Versatic™ 10) in dearomatized hydrocarbon fluid (Escaid™ 110) containing 1 g / L butylhydroxytoluene (BHT).

[0061] Solvent extraction is performed in step k) using an organic solvent suitable for extracting lithium cations from an aqueous solution. Examples of suitable organic solvents include synergistic extractant mixtures comprising a betadiketone and a neutral extractant, e.g. an organic phosphate, as disclosed in J Chem Technol Biotechnol 2016; 91 : 2549-2562 (table 3); Hydrometallurgy 154 (2015) 33-39; and Hydrometallurgy 175 (2018) 35-42. Further 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 OPR1R2R3, 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 k) comprises benzoyltrifluoroacetone (HBTA) and tri-n-octylphosphine oxide (TOPO). In some embodiments, the solvent used in step k) comprises thenoyltrifluoroacetone (TTA) and tri-n-octylphosphine oxide (TOPO). In some embodiments, the solvent used in step k) is a solution of 27 vol% Cyanex® 936P in dearomatized hydrocarbon fluid (Escaid™ 110).

[0062] The present disclosure also provides a production plant suitable for performing the process of the present disclosure. In some embodiments, 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 contacted 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.

[0063] The production plant comprises at least one first continuous stirred-tank reactor (CSTR) configured to receive an aqueous effluent of the extraction module of the first SX unit, if a first SX unit is present, or, in the alternative, to receive an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations. If a first SX unit is present, the first CSTR is located downstream of the first SX unit. The at least one first CSTR comprises a dosing device for liquids, heating / cooling means, and gas injection means. Suitable continuous stirred- tank reactors are known in the art.

[0064] 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.

[0065] The production plant also comprises at least one second continuous stirred-tank reactor (CSTR) configured to receive an aqueous effluent of the at least one first solid / liquid separation device. The second CSTR thus is located downstream of the first solid / liquid separation device. The first CSTR comprises a dosing device for liquids and heating / cooling means. Suitable continuous stirred-tank reactors are known in the art.

[0066] 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 first solid / liquid separation device comprises a filter press.

[0067] The production plant further comprises a second solvent extraction (SX) unit configured to receive an aqueous effluent of the at least one second solid / liquid separation device. The second 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.

[0068] 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 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.

[0069] The production plant further comprises a fourth solvent extraction (SX) unit configured to receive an aqueous effluent of the extraction module of the third SX unit. The fourth 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.

[0070] The production plant also comprises at least one third continuous stirred-tank reactor (CSTR) configured to receive an aqueous effluent of the extraction module of the fourth SX unit. The third CSTR thus is located downstream of the fourth SX unit. The third CSTR comprises a dosing device for liquids and heating / cooling means. Suitable continuous stirred-tank reactors are known in the art. The production plant further comprises at least one third solid / liquid separation device configured to receive an effluent of the third CSTR. The at least one third solid / liquid separation device thus is located downstream of the third CSTR. In some embodiments, the third solid / liquid separation device comprises a filter press.

[0071] The production plant further comprises a fifth solvent extraction (SX) unit configured to receive an aqueous effluent of the third solid / liquid separation device. The fifth 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.

[0072] The production plant further comprises at least one fourth continuous stirred- tank reactor (CSTR) configured to receive an aqueous effluent of the scrubbing and stripping module of the second SX unit. The fourth CSTR thus is located downstream of the second SX unit. The fourth CSTR comprises a dosing device for liquids and heating / cooling means. Suitable continuous stirred-tank reactors are known in the art.

[0073] The production plant further comprises at least one fourth solid / liquid separation device configured to receive an effluent of the fourth CSTR. The at least one fourth solid / liquid separation device thus is located downstream of the fourth CSTR. In some embodiments, the fourth solid / liquid separation device comprises a filter press.

[0074] The production plant further comprises at least one fifth continuous stirred-tank reactor (CSTR) configured to receive an aqueous effluent of the fourth solid / liquid separation device. The fifth CSTR thus is located downstream of the fourth solid / liquid separation device. The fifth CSTR comprises a dosing device for liquids and heating / cooling means. Suitable continuous stirred-tank reactors are known in the art.

[0075] The production plant further comprises at least one fifth solid / liquid separation device configured to receive an effluent of the fifth CSTR. The at least one fifth solid / liquid separation device thus is located downstream of the fifth CSTR. In some embodiments, the third solid / liquid separation device comprises a filter press.

[0076] The production plant further comprises a first crystallizer configured to receive an aqueous effluent of the scrubbing and stripping module of the third SX unit and to produce crystals of a first metal salt. Suitable crystallizers are known in the art.

[0077] The production plant further comprises a second crystallizer configured to receive an aqueous effluent of the scrubbing and stripping module of the fourth SX unit and to produce crystals of a second metal salt. Suitable crystallizers are known in the art.

[0078] The production plant further comprises a third crystallizer configured to receive an aqueous effluent of the scrubbing and stripping module of the fifth SX unit and to produce crystals of a third metal salt. Suitable crystallizers are known in the art.

[0079] In some embodiments of the production plant, the first solid / liquid separation device, the second solid / liquid separation device, the third solid / liquid separation device, the fourth solid / liquid separation device, and the fifth solid / liquid separation device each comprise a filter press.

[0080] In some embodiments, the production plant additionally comprises a sixth continuous stirred-tank reactor (CSTR) configured to receive an aqueous effluent of the second solid / liquid separation device. The sixth CSTR thus is located downstream of the second solid / liquid separation device. The sixth CSTR comprises a dosing device for liquids, heating / cooling means, and gas injection means. Suitable continuous stirred-tank reactors are known in the art.

[0081] In these embodiments, the production plant further comprises at least one sixth solid / liquid separation device configured to receive an effluent of the sixth CSTR. The at least one sixth solid / liquid separation device thus is located downstream of the sixth CSTR. In some embodiments, the sixth solid / liquid separation device comprises a filter press.

[0082] In these embodiments, the production plant additionally comprises a seventh continuous stirred-tank reactor (CSTR) configured to receive solids from the sixth solid / liquid separation device. The seventh CSTR thus is located downstream of the sixth solid / liquid separation device. The seventh CSTR comprises a dosing device for liquids, heating / cooling means, and gas injection means. Suitable continuous stirred-tank reactors are known in the art.

[0083] In these embodiments, the production plant further comprises at least one seventh solid / liquid separation device configured to receive an effluent of the seventh CSTR and configured to transfer the mother liquor produced to an inlet of the second SX unit. The at least one seventh solid / liquid separation device thus is located downstream of the seventh CSTR and upstream of the second SX unit. In some embodiments, the seventh solid / liquid separation device comprises a filter press.

[0084] In some embodiments, the production plant additionally comprises a sixth solvent extraction (SX) unit configured to receive an aqueous effluent of the second crystallizer. The sixth SX unit comprises an extraction module configured to deliver a stream of an organic solvent loaded with metal cations to an organic solvent circuit of the third SX unit, and to deliver an aqueous effluent stream to the third CSTR. 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 an organic solvent circuit of the third SX unit. The aqueous phase depleted of metal cations is delivered to the third CSTR. Suitable solvent extraction (SX) units are known in the art.

[0085] Detailed description of the drawings

[0086] A schematic diagram of an exemplary production plant of the present disclosure is shown in Fig. 1 .

[0087] 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 1001. 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 1002. In an exemplary process, copper cations are extracted from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations 1000 first solvent extraction (SX) unit 10 and transferred to the aqueous effluent 1002. Metallic copper can be recovered from the aqueous effluent 1002, e.g., by electrowinning.

[0088] The production plant further comprises a first continuous stirred-tank reactor (CSTR) 70 which is configured to receive an aqueous effluent 1001 of the extraction module 11 of the first SX unit 10. The CSTR 70 comprises a dosing device for liquids, heating / cooling means, and gas injection means. In the CSTR 70, a solution comprising sodium carbonate is added to precipitate impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution. Air is injected into the mixture to oxidize any Fe(ll) present to Fe(lll) and to maximize precipitation of iron from the liquid phase.

[0089] The production plant further comprises at least one first solid / liquid separation device 140 which is configured to receive an effluent 7001 of the first CSTR 70. In the at least one first solid / liquid separation device 140, metal salts 14002 of the impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution are recovered from the effluent of the first CSTR 70 by solid / liquid separation, e.g., filtration. The solids 14002 usually are discarded.

[0090] The production plant further comprises a second continuous stirred-tank reactor (CSTR) 80 which is configured to receive an aqueous effluent 14001 of the first solid / liquid separation device 140. The CSTR 80 comprises a dosing device for liquids and heating / cooling means. In the CSTR 80, a solution comprising sodium carbonate is added to precipitate further impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution from the solution.

[0091] The production plant further comprises at least one second solid / liquid separation device 150 which is configured to receive an effluent 8001 of the second CSTR 80. In the at least one second solid / liquid separation device 150, metal salts 15002 of impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, or Si present in the solution are recovered from the effluent of the second CSTR 80 by solid / liquid separation, e.g., filtration. As the solids 15002 may contain significant amounts of value metals like nickel and cobalt, they can be recycled into a leaching step for generating an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations 1000.

[0092] The production plant further comprises a second solvent extraction (SX) unit 20 which is configured to receive an aqueous effluent 15001 of the second solid / liquid separation device 150. The second SX unit 20 comprises an extraction module 21 and a scrubbing and stripping module 22. The aqueous effluent 15001 entering the second SX unit 20 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.

[0093] The production plant further comprises a third solvent extraction (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 30 comprises an extraction module 31 and a scrubbing and stripping module 32. The aqueous effluent 2001 entering the third SX unit 30 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.

[0094] The production plant further comprises a fourth solvent extraction (SX) unit 40 which is configured to receive an aqueous effluent 3001 of the extraction module 31 of the third SX unit 30. The fourth SX unit 40 comprises an extraction module 41 and a scrubbing and stripping module 42. The aqueous effluent 3001 entering the fourth SX unit 40 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.

[0095] The production plant further comprises a third continuous stirred-tank reactor (CSTR) 90 which is configured to receive an aqueous effluent 4001 of the extraction module 41 of the fourth SX unit 40. The CSTR 90 comprises a dosing device for liquids and heating / cooling means. In the CSTR 90, a solution comprising sodium hydroxide is added to precipitate magnesium hydroxide.

[0096] The production plant further comprises at least one third solid / liquid separation device 160 which is configured to receive an effluent 9001 of the third CSTR 90. In the at least one third solid / liquid separation device 160, magnesium hydroxide 16002 is recovered from the effluent of the third CSTR 90 by solid / liquid separation, e.g., filtration.

[0097] The production plant further comprises a fifth solvent extraction (SX) unit 50 which is configured to receive an aqueous effluent 16001 of the third solid / liquid separation device 160. The fifth SX unit 50 comprises an extraction module 51 and a scrubbing and stripping module 52. The aqueous effluent 16001 entering the fifth SX unit 50 is extracted with an organic solvent in the extraction module 51. The extracted aqueous phase leaves the extraction module 51 as an aqueous effluent 5001. The loaded organic phase is transferred to the scrubbing and stripping module 52, 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 51 , and the acidic aqueous solution comprising the metal cations from the organic phase leaves the scrubbing and stripping module 52 as an aqueous effluent 5002. The production plant further comprises a fourth CSTR 100 which is configured to receive an aqueous effluent 2002 from the scrubbing and stripping module 22 of the second SX unit 20. The fourth CSTR 100 comprises a dosing device for liquids, heating / cooling means, and gas injection means. In the fourth CSTR 100, an alkaline solution is added to precipitate manganese carbonate and / or manganese hydroxide.

[0098] The production plant further comprises at least one fourth solid / liquid separation device 170 which is configured to receive an effluent 10001 of the fourth CSTR 100. In the at least one fourth solid / liquid separation device 170, manganese carbonate and / or manganese hydroxide 17002 is recovered from the effluent 10001 of the fourth CSTR 100 by solid / liquid separation, e.g., filtration.

[0099] The production plant further comprises a fifth CSTR 110 which is configured to receive an aqueous effluent 17001 from the fourth solid / liquid separation device 170. The fifth CSTR 110 comprises a dosing device for liquids and heating / cooling means. In the fifth CSTR 110, an alkaline solution is added to precipitate metal hydroxides.

[0100] The production plant further comprises at least one fifth solid / liquid separation device 180 which is configured to receive an effluent 11001 of the fifth CSTR 110. In the at least one fifth solid / liquid separation device 180, metal hydroxides 18002 are recovered from the effluent 11001 of the fifth CSTR 110 by solid / liquid separation, e.g., filtration.

[0101] The production plant further comprises a first crystallizer 210 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 first metal salt, e.g., cobalt sulfate.

[0102] The production plant further comprises a second crystallizer 220 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 second metal salt, e.g., nickel sulfate.

[0103] The production plant further comprises a third crystallizer 230 configured to receive an aqueous effluent 5002 of the scrubbing and stripping module 52 of the fifth SX unit 50 and to produce crystals of a third metal salt, e.g., lithium sulfate.

[0104] The production plant further comprises a sixth SX unit 60 which is configured to receive an aqueous effluent 4003 of the second crystallizer 220. The sixth SX unit 60 comprises an extraction module 61 configured to deliver a stream of an organic solvent loaded with metal cations 6002 to an organic solvent circuit of the third SX unit 30 and to deliver an aqueous effluent stream 6001 to the third CSTR 90. The aqueous effluent 4003 from the second crystallizer 220 is extracted with an organic solvent in the extraction module 61. The extracted aqueous phase leaves the extraction module 61 as an aqueous effluent 6001 and is transferred to the third CSTR 90. The loaded organic phase leaves the extraction module 61 as an organic effluent 6002 and is recycled to an organic solvent circuit of the third SX unit 30.

[0105] Fig. 2 shows a section of another exemplary production plant of the present disclosure. In this embodiment of the production plant, the section shown in Fig. 2 has been added to the production plant shown in Fig. 1. The dotted lines in Fig. 2 indicate the interfaces of the section with the production plant shown in Fig. 1.

[0106] In this embodiment, the production plant further comprises a sixth CSTR 120 which is configured to receive an aqueous effluent 15001 of the second solid / liquid separation device 150. The sixth CSTR 120 comprises a dosing device for liquids, heating / cooling means, and gas injection means. In the sixth CSTR 120, an alkaline solution is added to precipitate a mixed metal hydroxide (MHP). The production plant further comprises at least one sixth solid / liquid separation device 190 which is configured to receive an effluent 12001 of the sixth CSTR 120. In the at least one sixth solid / liquid separation device 190, a mixed metal hydroxide 19002 is recovered from the effluent 12001 of the sixth CSTR 120 by solid / liquid separation, e.g., filtration. The mother liquor 19001 which comprises lithium, sodium, and magnesium cations can be fed to the third CSTR 90.

[0107] The production plant further comprises a seventh CSTR 130 which is configured to receive a solid 19002 from the at least one sixth solid / liquid separation device 190. The seventh CSTR 130 comprises a dosing device for liquids, heating / cooling means, and gas injection means. In the seventh CSTR 130, sulfuric acid is added to dissolve the mixed metal hydroxide 19002.

[0108] The production plant further comprises at least one seventh solid / liquid separation device 200 which is configured to receive an effluent 13001 of the seventh CSTR 130. In the at least one seventh solid / liquid separation device 200, any solids remaining in the effluent 13001 of the seventh CSTR 130 are removed by solid / liquid separation, e.g., filtration. The aqueous effluent 20001 of the at least one seventh solid / liquid separation device 200 is transferred to an inlet of the extraction module 21 of the second SX unit 20.

[0109] Examples

[0110] Example 1 Two-stage impurity precipitation

[0111] A pregnant leach solution (PLS) having the composition as shown in Table 1 (Feed solution) was fed to a first CSTR and its pH was adjusted to a value of

[0112] 3.1 to 3.4 at 80°C by addition of an alkaline solution comprising 250 g / l Na2CO3. The precipitate formed was filtered off in a subsequent filter unit and the filtrate was fed to a second CSTR and its pH was adjusted to a value of 4.5 to 4.8 at 80°C by addition of an alkaline solution comprising 250 g / l Na2CO3. The precipitate formed was filtered off in a subsequent filter unit and recycled into the first CSTR. The filtrate obtained had the composition shown in Table 1 (Final solution). Metal losses observed in the first precipitation step (pH = 3.4) were: Ni 3.3 %, Li 1 .5 %, Co 0.3% and Mn 0% Table 1 Example 2 Solvent extraction a) Cu SX

[0113] A feed solution comprising 3.535 g / l Cu, 5.596 g / l Li, 9.942 g / l Mn, 7.433 g / l Co, and 32.075 g / l Ni was fed to a first SX unit. Copper cations were extracted using 25 wt% LIX984 in Exxsol D80 as extractant. The ratio of organic phase to aqueous phase (O:A) was 1.1 :1. The aqueous feed had a pH of 1.5 and a temperature of 40°C. Li loss was smaller than the detection limit, i.e. <1 mg / kg. Extraction efficiency for copper was 99.2%. The organic phase was scrubbed with a CuSC solution comprising 3.4 g / L Cu and having a pH of 0.8 at an O:A of 30-50:1. Stripping of the organic phase was performed using an aqueous feed solution containing 27 g / L Cu in 190 g / L ^SC and having a pH of <0 at an O:A ratio of 2: 1. Stripping efficiency was 90%; overall Li losses amounted to 2 mg / L (0.04%). b) Mn I impurity SX

[0114] The aqueous effluent of the first SX unit was fed into the impurity precipitation. The resulting filtrate comprising 5.918 g / l Li, 11.513 g / l Mn, 8.555 g / l Co, and 32.343 g / l Ni was fed to a second SX unit. Impurity cations were extracted using 40 wt% DE2HPA in Exxsol D80 as extractant. The ratio of organic phase to aqueous phase (O:A) was 1.85-2:1. Saponification degree of the organic extractant was 50%. The aqueous feed had a pH of 3.5 and a temperature of 40°C. Li loss was 310 mg / kg (5.24%), and extraction efficiency for manganese was >99%. The organic phase was scrubbed with 90 - 200 g / L H2SO4 at a pH of 1 .6-2.0 and at an O:A ratio of 30-50:1. Scrubbing efficiencies were 99.6% for Co, 97% for Li, 94.8% for Mn, 97% for Na, and 100% for Ni. Stripping of the organic phase was performed using an aqueous feed solution containing 50 g / L H2SO4 and having a pH of 0.8 at an O:A ratio of 1.3-2:1. Stripping efficiency was 100%; overall Li losses amounted to 9 mg / L (0.15%). c) Co SX

[0115] The aqueous effluent of the second SX unit comprising 5.014 g / l Li, 6.796 g / l

[0116] Co, and 27.979 g / l Ni was fed to a third SX unit. Cobalt cations were extracted using 17.5-22.5 wt% Cyanex 272 in Exxsol D80 as extractant. The ratio of organic phase to aqueous phase (O:A) was 1.4-2.0:1. Saponification degree of the organic extractant was 30%. The aqueous feed had a pH of 4.2-6 and a temperature of 48-53°C. Li loss was 323 mg / kg (6.44%), and extraction efficiency for cobalt was 99.7%. The organic phase was scrubbed with an acidic aqueous solution having a pH of 3.7 and at an O:A ratio of 30:1 . Stripping of the organic phase was performed using an aqueous feed solution containing 165 g / L H2SO4 at a pH of 1.5 and at an O:A ratio of 18.5:1. Stripping efficiency was >99.5%, overall Li losses amounted to < 1 ppm. d) Ni SX

[0117] The aqueous effluent of the third SX unit comprising 5.045 g / l Li, and 26.926 g / l Ni was fed to a fourth SX unit. Nickel cations were extracted using 27-33 wt% Versatic 10 in Exxsol D80 as extractant. The ratio of organic phase to aqueous phase (O:A) was 2:1 . Saponification degree of the organic extractant was in the range of from 10 to 47%. The aqueous feed had a pH of 6.7 and a temperature of 40-55°C. Extraction efficiency for nickel was 99.9%. The organic phase was scrubbed with diluted sulfuric acid at a pH of 5.3 and at an O:A of 1 :1. Scrubbing efficiency was 99.6% for Li. Stripping of the organic phase was performed using an aqueous feed solution containing 20% H2SO4 at a pH of 1.8. Overall Li losses amounted to 2 mg / kg (0,43%). e) Li SX

[0118] The aqueous effluent of the fourth SX unit was fed to a fifth SX unit. Lithium cations were extracted using 40 wt% Cyanex 936P in Exxsol D80 as extractant. The ratio of organic phase to aqueous phase (O:A) was 0.75:1. The aqueous feed had a pH of 12-13 and a temperature of 30-35°C. The organic phase was scrubbed at an O:A of 20:1 . Stripping of the organic phase was performed using diluted H2SO4 at a pH of 2.5. Example 3 Data of exemplary production plant

[0119] For an exemplary production plant, Table 2 shows the feed composition for producing an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations from lithium ion battery materials. Both the mass fraction of the individual elements in the feed and the total mass per year fed to the production plant are listed. Table 3 lists the yearly amounts of several products obtained from the production plant. Table 4 shows the composition of the liquid effluent from the impurity precipitation stage of the production plant. 483.39 to / day of liquid effluent are produced. Table 5 shows the composition of the filter cake from the Mg precipitation stage of the production plant. 0.51 to / day of solids are produced. Table 6 shows the composition of liquid effluent from the Li solvent extraction stage of the production plant. 2040.08 to / day of liquid effluent are produced. Table 2 Table 3

[0120] Table 4

[0121] Table 5

[0122] Table 6

[0123] List of reference numerals

[0124] 10 First SX unit

[0125] 11 Extraction module of first SX unit

[0126] 12 Scrubbing and stripping module of first SX unit

[0127] 20 Second SX unit

[0128] 21 Extraction module of second SX unit

[0129] 22 Scrubbing and stripping module of second SX unit

[0130] 30 Third SX unit

[0131] 31 Extraction module of third SX unit

[0132] 32 Scrubbing and stripping module of third SX unit

[0133] 40 Fourth SX unit

[0134] 41 Extraction module of fourth SX unit

[0135] 42 Scrubbing and stripping module of fourth SX unit

[0136] 50 Fifth SX unit

[0137] 51 Extraction module of fifth SX unit

[0138] 52 Scrubbing and stripping module of fifth SX unit

[0139] 60 Sixth SX unit

[0140] 61 Extraction module of sixth SX unit

[0141] 70 First CSTR

[0142] 80 Second CSTR

[0143] 90 Third CSTR

[0144] 100 Fourth CSTR

[0145] 110 Fifth CSTR

[0146] 120 Sixth CSTR

[0147] 130 Seventh CSTR

[0148] 140 First solid / liquid separation unit

[0149] 150 Second solid / liquid separation unit

[0150] 160 Third solid / liquid separation unit

[0151] 170 Fourth solid / liquid separation unit

[0152] 180 Fifth solid / liquid separation unit

[0153] 190 Sixth solid / liquid separation unit

[0154] 200 Seventh solid / liquid separation unit

[0155] 210 First crystallizer 220 Second crystallizer

[0156] 230 Third crystallizer

[0157] 1000 Acidic aqueous solution comprising Ni, Co, Mn, and Li cations

[0158] 1001 Aqueous effluent of extraction module of first SX unit

[0159] 1002 Aqueous effluent of scrubbing and stripping module of first SX unit (Cu)

[0160] 2001 Aqueous effluent of extraction module of second SX unit

[0161] 2002 Aqueous effluent of scrubbing and stripping module of second SX unit

[0162] 3001 Aqueous effluent of extraction module of third SX unit

[0163] 3002 Aqueous effluent of scrubbing and stripping module of third SX unit

[0164] 4001 Aqueous effluent of extraction module of fourth SX unit

[0165] 4002 Aqueous effluent of scrubbing and stripping module of fourth SX unit

[0166] 4003 Aqueous effluent of second crystallizer

[0167] 5001 Aqueous effluent of extraction module of fifth SX unit

[0168] 5002 Aqueous effluent of scrubbing and stripping module of fifth SX unit

[0169] 6001 Aqueous effluent of extraction module of sixth SX unit

[0170] 6002 Organic effluent of extraction module of sixth SX unit

[0171] 7001 Effluent of first CSTR

[0172] 8001 Effluent of second CSTR

[0173] 9001 Effluent of third CSTR

[0174] 10001 Effluent of fourth CSTR

[0175] 11001 Effluent of fifth CSTR

[0176] 12001 Effluent of sixth CSTR

[0177] 13001 Effluent of seventh CSTR

[0178] 14001 Aqueous effluent of first solid / liquid separation unit

[0179] 14002 Solids (impurity salts)

[0180] 15001 Aqueous effluent of second solid / liquid separation unit

[0181] 15002 Solids (impurity salts)

[0182] 16001 Aqueous effluent of third solid / liquid separation unit

[0183] 16002 Solids (magnesium hydroxide)

[0184] 17001 Aqueous effluent of fourth solid / liquid separation unit

[0185] 17002 Solids (manganese hydroxide and / or carbonate)

[0186] 18001 Aqueous effluent of fifth solid / liquid separation unit 18002 Solids (metal hydroxides)

[0187] 19001 Aqueous effluent of sixth solid / liquid separation unit

[0188] 19002 Solids (MHP)

[0189] 20001 Aqueous effluent of seventh solid / liquid separation unit 20002 Solids (insoluble residue)

Claims

Claims1 . A continuous process for recovering metal salts from an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations, the process comprising a) optionally, adjusting the pH value of the solution to a value in the range of from 1.5 to 2.5 and recovering copper from the solution by solvent extraction, or by precipitation of copper sulfide, followed by solid / liquid separation, b) adjusting the pH of the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations to be in the range of from 3.0 to 4.0 by addition of sodium carbonate, and subsequently precipitating impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, Al, and / or Si present in the solution from the solution, c) removing solids from the mixture obtained in step b), d) adjusting the pH of the acidic aqueous solution obtained in step c) to be in the range of from 4.5 to 5.0 by addition of sodium carbonate, and subsequently precipitating impurity cations of the group consisting of Al and Fe cations and impurity anions comprising P, F, Al, and / or Si present in the solution from the solution, e) removing solids from the mixture obtained in step d), f) adjusting the pH of the acidic aqueous solution obtained in step e) to be in the range of from 2 to 4, and subsequently removing manganese cations and any residual impurity cations of the group consisting of Ca, Cu, Zn, and Cd cations 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 andstripping the solvent comprising manganese cations and impurity cations with sulfuric acid to obtain an acidic aqueous solution comprising manganese cations and impurity cations, g) adjusting the pH of the aqueous solution depleted of manganese cations and impurity cations obtained in step f) 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, h) adjusting the pH of the aqueous solution depleted of cobalt cations obtained in step g) 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, i) adding sodium hydroxide to the aqueous solution depleted of nickel cations obtained in step h), adjusting the pH of to be in the range of from 10 to 12.5, and precipitating magnesium hydroxide from the solution, j) removing solids from the mixture obtained in step i), k) adjusting the pH of the aqueous solution obtained in step j) 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 l) adjusting the pH of the acidic aqueous solution comprising manganese cations and impurity cations obtained in step f) to be in the range of from 6.8 to 8.5, and precipitating manganese carbonate and / or manganese hydroxide from the solution, m) removing solids from the mixture obtained in step I), n) optionally, adjusting the pH of the solution obtained in step I) to be in the range of from 10 to 12.5, and precipitating metal hydroxides from the solution, o) optionally, removing solids from the mixture obtained in step n).

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

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

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

6. The process of any one of claims 1 to 5, additionally comprising s) adjusting the pH of the aqueous solution obtained in step e) to be in the range of from 7 to 8.5, and precipitating a mixed metal hydroxide and / or mixed metal carbonate from the solution, t) performing a solid / liquid separation of the mixture obtained in step s) to obtain solid mixed metal hydroxide and / or mixed metal carbonate and a mother liquor, u) dissolving the solid mixed metal hydroxide and / or mixed metal carbonate obtained in step t) in sulfuric acid, v) removing residual solids from the solution obtained in step u), w) feeding the solution obtained in step v) into step f),x) feeding the mother liquor obtained in step t) into step i).

7. The process of any one of claims 4 to 6, additionally comprising y) performing solvent extraction of the mother liquor obtained after crystalizing nickel sulfate in step q) to obtain an aqueous solution depleted of nickel cations and a solvent comprising nickel cations; and feeding the solvent comprising nickel cations into step g).

8. The process of any one of claims 1 to 7, wherein the solvent used in step f) is a solution of 40 vol% bis(2-ethylhexyl)phosphate in dearomatized hydrocarbon fluid.

9. The process of any one of claims 1 to 8, wherein the solvent used in step g)is a solution of 20 vol% bis-(2,4,4-trimethylpentyl) phosphinic acid in dearomatized hydrocarbon fluid containing 1 g / L butylhydroxytoluene.

10. The process of any one of claims 1 to 9, wherein the solvent used in step h) is a solution of 30 vol% neodecanoic acid in dearomatized hydrocarbon fluid containing 1 g / L butylhydroxytoluene.

11. A production plant comprising(1 ) a first solvent extraction (SX) unit (10) configured to receive an acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations (1000), the first SX unit (10) comprising i. an extraction module (11 ), ii. a scrubbing and stripping module (12),(2) at least one first continuous stirred-tank reactor (CSTR) (70) configured to receive an aqueous effluent (1001 ) of the extraction module (11 ) of the first SX unit (10), the first CSTR (70) comprising i. a dosing device for liquids, ii. heating / cooling means, iii. gas injection means,(3) at least one first solid / liquid separation device (140) configured to receive an effluent (7001) of the first CSTR (70),(4) at least one second continuous stirred-tank reactor (CSTR) (80) configured to receive an effluent (14001) of the first solid / liquid separation device (140), the second CSTR (80) comprising i. a dosing device for liquids, ii. heating / cooling means,(5) at least one second solid / liquid separation device (150) configured to receive an effluent (8001) of the second CSTR (80),(6) a second solvent extraction (SX) unit (20) configured to receive an aqueous effluent (15001) of the second solid / liquid separation device (150), the second SX unit (20) comprising i. an extraction module (21 ), ii. a scrubbing and stripping module (22),(7) a third solvent extraction (SX) unit (30) configured to receive an aqueous effluent (2001 ) of the extraction module (21 ) of the second SX unit (20), the third SX unit (30) comprising i. an extraction module (31 ), ii. a scrubbing and stripping module (32),(8) a fourth solvent extraction (SX) unit (40) configured to receive an aqueous effluent (3001) of the extraction module (31 ) of the third SX unit (30), the fourth SX unit (40) comprising i. an extraction module (41 ), ii. a scrubbing and stripping module (42),(9) at least one third continuous stirred-tank reactor (CSTR) (90) configured to receive an aqueous effluent (4001 ) of the extraction module (41 ) of the fourth SX unit (40), the third CSTR (90) comprising i. a dosing device for liquids, ii. heating / cooling means,(10) at least one third solid / liquid separation device (160) configured to receive an effluent (9001) of the third CSTR (90),(11 ) a fifth solvent extraction (SX) unit (50) configured to receive an aqueous effluent (16001 ) of the third solid / liquid separation device (160), the fifth SX unit (50) comprising i. an extraction module (51 ), ii. a scrubbing and stripping module (52),(12) at least one fourth continuous stirred-tank reactor (CSTR) (100) configured to receive an aqueous effluent (2002) of the scrubbing and stripping module (22) of the second SX unit (20), the second CSTR (100) comprising i. a dosing device for liquids, ii. heating / cooling means, iii. gas injection means,(13) at least one fourth solid / liquid separation device (170) configured to receive an effluent (10001 ) of the fourth CSTR (100),(14) at least one fifth continuous stirred-tank reactor (CSTR) (110) configured to receive an effluent (17001 ) of the fourth solid / liquid separation device (170), the fifth CSTR (110) comprising i. a dosing device for liquids, ii. heating / cooling means,(15) at least one fifth solid / liquid separation device (180) configured to receive an effluent (11001 ) of the fifth CSTR (110),(16) a first crystallizer (210) 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 first metal salt,(17) a second crystallizer (220) 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 second metal salt,(18) a third crystallizer (230) configured to receive an aqueous effluent (5002) of the scrubbing and stripping module (52) of the fifth SX unit (50) and to produce crystals of a third metal salt.

12. The production plant of claim 11 , wherein the first solid / liquid separation device (140), the second solid / liquid separation device (150), the thirdsolid / liquid separation device (160), the fourth solid / liquid separation device (170), and the fifth solid / liquid separation device (180) each comprise a filter press.

13. The production plant of claim 11 or 12, additionally comprising(19) at least one sixth continuous stirred-tank reactor (CSTR) (120) configured to receive an aqueous effluent (15001) of the second solid / liquid separation device (150), the sixth CSTR (120) comprising i. a dosing device for liquids, ii. heating / cooling means, iii. gas injection means,(20) at least one sixth solid / liquid separation device (190) configured to receive an effluent (12001 ) of the sixth CSTR (120),(21 ) at least one seventh continuous stirred-tank reactor (CSTR) (130) configured to receive solids (19002) from the sixth solid / liquid separation device (190), the seventh CSTR (130) comprising i. a dosing device for liquids, ii. heating / cooling means, iii. gas injection means,(22) at least one seventh solid / liquid separation device (200) configured to receive an effluent (13001) of the seventh CSTR (130) and configured to transfer the mother liquor (20001 ) produced to an inlet of the extraction module (21) of the second SX unit (20).

14. The production plant of any one of claims 11 to 13, additionally comprising(23) a sixth solvent extraction (SX) unit (60) configured to receive an aqueous effluent (4003) of the second crystallizer (220), the sixth SX unit (60) comprising an extraction module (61 ) configured to deliver a stream of a organic solvent loaded with metal cations (6002) to a solvent circuit of the third SX unit (30), and to deliver an aqueous effluent stream (6001 ) to the third CSTR (90).

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