WO2025132849A1

WO2025132849A1 - Mixed metal hydroxides battery material precursor from battery recycling feeds

Info

Publication number: WO2025132849A1
Application number: PCT/EP2024/087489
Authority: WO
Inventors: Vincent Smith; Bernard Muller; Tomi Oja; Joop Enno FRERICHS; Kathrin Michel; Rafael Benjamin BERK; Regina Vogelsang; Kerstin Schierle-Arndt; Wolfram WILK; Maximilian RANG; Anne-Marie Caroline ZIESCHANG; Wolfgang Rohde; Fabian Seeler
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2023-12-19
Filing date: 2024-12-19
Publication date: 2025-06-26
Anticipated expiration: 2026-06-19

Abstract

The present disclosure relates to a continuous process and a production plant for producing a mixed metal hydroxide battery material precursor from battery recycling feeds comprising nickel, cobalt, manganese, and lithium cations.

Description

Mixed metal hydroxides battery material precursor from battery recycling feeds

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.

Field of the invention

Background

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.

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. 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.

CN 111 455 171 A discloses a method of extracting valuable metal from a seabed polymetallic nodule resource, in particular to a method of using the seabed polymetallic nodule resource as a raw material to produce copper sulfate, manganese sulfate, titanium dioxide, a lithium battery ternary cathode material precursor and a titanium-doped cathode material through a whole wet method process. The seabed polymetallic nodule resource is subjected to sulfuric acid high-pressure leaching operation, copper, nickel, cobalt and manganese in leachate are subjected to chemical precipitation, extraction separation and purification, a nickel cobalt manganese sulfate solution which is obtained through combined extraction is subjected to chemical precipitation to produce the lithium battery ternary cathode material precursor, and the precursor is subjected to lithiation, titanium doping and calcination operation, so that the titanium-doped ternary cathode material is obtained.

The hydrometallurgical process of battery recycling to obtain battery grade Ni, Mn and Co sulfates includes various recovery and purification steps, like solvent extraction. Combining this hydrometallurgical process with the precipitation of a cathode material precursor, the first step in the production of cathode active materials for lithium-ion batteries, would offer the opportunity to skip purification steps and save costs. A prerequisite to precipitate the precursor is a sufficiently high metal concentration of about 80 g/l nickel. In the hydrometallurgical recycling process, bases like NaOH or Na₂CO3 are commonly used for pH adjustment in all process steps after acid leaching, leading to Na₂S0₄ formation. This leads to high Na load and prohibits achieving sufficient nickel concentration by evaporation of a recycling feed (e.g., before Ni solvent extraction), as a NiNa(SO₄)₂ double salt is formed and the minimum nickel concentration cannot be achieved.

It is an object of the present disclosure to provide an improved recycling plant an improved recycling process for lithium ion battery materials which allows for producing a mixed metal hydroxides battery material precursor.

Summary of the invention

The process of the present disclosure improves the prior art hydrometallurgical recycling process either by replacing NaOH by alternative bases like CaO, Ca(OH)₂ or MHP (commercial mixed metal hydroxide precipitate from mining) in some of the recycling process steps.

The present disclosure provides a continuous process for producing a mixed metal battery material precursor. The process involves providing an aqueous acidic solution comprising nickel, cobalt, manganese, and lithium cations, which has been obtained by acid leaching of a lithium-ion battery material, removing manganese cations and 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 by precipitation, followed by solvent extraction of manganese and impurity cations, solvent extraction of cobalt cations, adding CoSO₄ and MnSO₄ to the aqueous solution depleted of cobalt cations, adding sodium hydroxide and ammonia to the solution and precipitating and recovering a precursor of an cathode active material for lithium-ion batteries.

The present disclosure also provides a production plant suitable for performing the continuous process of the present disclosure. Brief description of the drawings

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

Detailed description

The present disclosure provides a continuous process for producing a mixed metal battery material precursor 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, manganese, iron, aluminum, magnesium, calcium, and/or titanium; as well as anions like fluoride and/or phosphate.

The continuous process of the present disclosure comprises the steps of a) optionally, adjusting the pH 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 calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, and/or MHP, 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 calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, and/or MHP, 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 acidic 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 an organic solvent comprising cobalt cations, and scrubbing and stripping the organic solvent comprising cobalt cations with sulfuric acid to obtain an acidic aqueous solution comprising cobalt cations, h) removing water from the aqueous solution depleted of cobalt cations obtained in step g) to obtain an aqueous solution having a nickel concentration of at least 80 g/l, i) adding cobalt sulfate and manganese sulfate to the solution to obtain a solution comprising nickel, cobalt, and manganese in a predetermined molar ratio, j) adding a base and a complexing agent to the solution obtained in step i) and precipitating a mixed metal battery material precursor from the solution, k) performing a solid/liquid separation of the mixture obtained in step j) to obtain a solid mixed metal battery material precursor and a mother liquor.

In some embodiments, the process further comprises the steps of l) adjusting the pH of the aqueous solution obtained in step k) 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 an organic solvent comprising lithium cations; and scrubbing and stripping the organic solvent comprising lithium cations with sulfuric acid to obtain an acidic aqueous solution comprising lithium cations.

In an optional first step a), copper is recovered by a first solvent extraction from the acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations.

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

A solvent extracting agent allows the metal ions 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 ions 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. 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.

In some embodiments, the first solvent extraction comprises

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

• adding a solvent extracting agent to the acidic aqueous solution, • homogenizing the mixture of acidic aqueous solution and solvent extracting agent,

• 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,

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

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

• homogenizing the mixture,

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

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

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).

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.

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

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.

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.

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).

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 calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, and/or MHP.

In the present disclosure, the term MHP (mixed hydroxide precipitate) means a mixture of metal hydroxides, hydroxycarbonates, and/or carbonates comprising nickel hydroxide, cobalt hydroxide and other metals, e.g., manganese. In some embodiments, the MHP is obtained by precipitating metal hydroxides from a metal salt solution. MHP typically comprises from 0 to 2 wt.% Li, from 10 to 50 wt.% Ni, from 0.1 to 20 wt.% Co, from 0.01 to 15 wt.% Mn. Moisture content generally is in the range of from 20 to 60 wt.%, relative to the total weight of MHP. A typical range for D(50) is from 1 to 150 pm. In some embodiments, the MHP is an intermediate nickel product produced from laterite nickel ore, which contains both nickel and a small percentage of cobalt. MHP is typically produced using a high-pressure acid leaching (HPAL) process. The mixed hydroxide precipitate (MHP) mostly consists of nickel hydroxide, but also contains valuable cobalt hydroxides and various other impurities, the main one being manganese. Ni content typically is 34-55 wt.%, Co content typically 1- 4.5 wt.%.

In some embodiments of the process, calcium oxide, calcium hydroxide, and/or calcium carbonate are added to generate a precipitate. In other embodiments of the process, barium oxide, barium hydroxide, and/or barium carbonate are added to generate a precipitate. In still other embodiments of the process, MHP is added to generate a precipitate.

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 calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, and/or MHP 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 oxidehydroxides 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. In some embodiments of the process, calcium oxide, calcium hydroxide, and/or calcium carbonate are added to generate a precipitate. In other embodiments of the process, barium oxide, barium hydroxide, and/or barium carbonate are added to generate a precipitate. In still other embodiments of the process, MHP is added to generate a precipitate.

The mother liquor is further processed in a second precipitation step d). The precipitation involves the addition of calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate and/or MHP 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. Iron, aluminum, magnesium, titanium, and copper precipitate from the solution as hydroxides and/or oxidehydroxides 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. In some embodiments of the process, calcium oxide, calcium hydroxide, and/or calcium carbonate are added to generate a precipitate. In other embodiments of the process, barium oxide, barium hydroxide, and/or barium carbonate are added to generate a precipitate. In still other embodiments of the process, MHP is added to generate a precipitate.

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 acidic aqueous solution comprising nickel, cobalt, manganese, and lithium cations to be in the range of from 2 to 4 by addition of calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, and/or MHP, and subsequently removing manganese cations and any impurity cations of the group consisting of Ca, Cu, Zn, and Cd present in the solution from the solution by solvent extraction to obtain an aqueous solution depleted of manganese cations and impurity cations and an organic solvent comprising manganese cations and impurity cations, and scrubbing and stripping the organic solvent comprising manganese cations and impurity cations with sulfuric acid to obtain an acidic aqueous solution comprising manganese cations and impurity cations. In some embodiments of the process, calcium oxide, calcium hydroxide, and/or calcium carbonate are added to adjust the pH. In other embodiments of the process, barium oxide, barium hydroxide, and/or barium carbonate are added to adjust the pH. In still other embodiments of the process, MHP is added to adjust the pH.

Solvent extraction is performed in step f) 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 f) is a solution of 40 vol% bis(2- ethylhexyljphosphate (D2EHPA) in dearomatized hydrocarbon fluid (Escaid™ 110).

The process further comprises g) adjusting the pH of the acidic 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 an organic solvent comprising cobalt cations, and scrubbing and stripping the organic solvent comprising cobalt cations with sulfuric acid to obtain an acidic aqueous solution comprising cobalt cations. In some embodiments of the process, the pH value is adjusted by addition of calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, and/or MHP. In some embodiments of the process, calcium oxide, calcium hydroxide, and/or calcium carbonate are added to adjust the pH. In other embodiments of the process, barium oxide, barium hydroxide, and/or barium carbonate are added to adjust the pH. In still other embodiments of the process, MHP is added to adjust the pH.

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 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). The process further comprises h) removing water from the aqueous solution depleted of cobalt cations obtained in step g) to obtain an aqueous solution having a nickel concentration of at least 80 g/l.

The process further comprises i) adding cobalt sulfate and manganese sulfate to the solution obtained in step h) to obtain a solution comprising nickel, cobalt, and manganese in a predetermined molar ratio. The molar ratio of Ni:Co:Mn = a:b:c in the solution is adjusted according to the values required for the desired battery material precursor, with a + b + c = 1 , a being in the range of from 0.6 to 0.95, b being in the range of from 0.025 to 0.2, c being in the range of from zero to 0.2. In an exemplary embodiment, the molar ratio of Ni:Co:Mn is 0.91 :0.045:0.045.

The process further comprises j) adding a base and a complexing agent to the solution obtained in step i) and precipitating a mixed metal battery material precursor from the solution. In step j), the pH value of the solution is adjusted to be in the range of from 10.0 to 13.5, e.g., from 10.0 to 12.7.

In some embodiments of the process, the base is selected from alkali metal hydroxides and/or carbonates. In some embodiments, hydroxides of sodium, potassium and/or lithium are used as base. In one embodiment, sodium hydroxide is used as base. In another embodiment, potassium hydroxide is used as base. In still another embodiment, lithium hydroxide is used as base. In other embodiments, a combination of alkali hydroxides is used as base. In some embodiments, the hydroxide concentration in the solution is in the range of from 0.1 to 12 mol/l, for instance, from 6 to 10 mol/l.

In some embodiments of the process, the complexing agent is ammonia and/or an organic acid or its alkali or ammonium salts, wherein said organic acid bears at least two functional groups per molecule and at least one of the functional groups is a carboxylate group. Examples of suitable organic acids bearing two identical functional groups are adipic acid, oxalic acid, succinic acid and glutaric acid. An example of organic acids bearing three identical functional groups is citric acid. In some embodiments of the process, the organic acid is selected from malic acid, tartaric acid, citric acid, and glycine. In one embodiment, ammonia is used as complexing agent.

In some embodiments of the process, the concentration of complexing agent(s) in the solution is in the range of from 1 to 30% by weight. When the complexing agent is ammonia, its concentration preferably is in the range of from 10 to 30% by weight. When the complexing agent(s) is or are selected from organic acids or their alkali or ammonium salts, the concentration of said complexing agent in the solution preferably is in the range of from 0.2 to 10% by weight.

The process further comprises k) performing a solid/liquid separation of the mixture obtained in step j) to obtain a solid mixed metal battery material precursor and a mother liquor. The mixed metal battery material precursors are (oxy)hydroxides or oxides comprising nickel and at least one transition metal selected from Co and Mn and optionally, at least one further element selected from Ti, Zr, Ca, Si, Mo, W, Al, Mg, Nb, and Ta.

The mixed metal battery material precursors of the present disclosure have an average particle diameter (D50) in the range of from 3 to 20 pm, e.g., from 5 to 15 pm, for instance, from 6 to 12 pm, determined by dynamic light scattering.

In one embodiment, the mixed metal battery material precursors are comprised of secondary particles comprising asymmetric plate-like shaped primary particles that have a thickness of 20 to 200 nm and a length of 50 to 500 nm.

In one embodiment, the primary particles are essentially radially aligned. The portion of radially aligned primary particles may be determined, e.g., by SEM (Scanning Electron Microscopy) of a cross-section of at least arbitrarily selected 5 secondary particles. “Essentially radially alignment” does not require a perfect radial orientation but includes that in an SEM analysis, a deviation to a perfectly radial orientation is at most 5 degrees.

The process further comprises I) adjusting the pH of the aqueous solution obtained in step k) 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 an organic solvent comprising lithium cations; and scrubbing and stripping the organic solvent comprising lithium cations with sulfuric acid to obtain an acidic aqueous solution comprising lithium cations.

Solvent extraction is performed in step I) 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 O=PRI R2R3, wherein each of Ri, R₂ and R₃ is 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 I) comprises benzoyltrifluoroacetone (HBTA) and tri-n-octylphosphine oxide (TOPO). In some embodiments, the solvent used in step I) comprises thenoyltrifluoroacetone (TTA) and tri-n-octylphosphine oxide (TOPO). In some embodiments, the solvent used in step I) is a solution of 27 vol% Cyanex® 936P in in dearomatized hydrocarbon fluid (Escaid™ 110).

In some embodiments, the process further comprises m) 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, and precipitating manganese carbonate and/or manganese hydroxide from the solution, n) removing solids from the mixture obtained in step m), o) optionally, adjusting the pH of the solution obtained in step n) to be in the range of from 10 to 12.5, and precipitating metal hydroxides from the solution, and p) optionally, removing solids from the mixture obtained in step o).

In some embodiments, the process further comprises q) crystalizing cobalt sulfate from the acidic aqueous solution comprising cobalt cations obtained in step g).

In some embodiments, the process further comprises r) crystalizing lithium sulfate from the acidic aqueous solution comprising lithium cations obtained in step I).

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 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. 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.

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.

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.

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.

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.

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.

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.

The production plant also comprises at least one third continuously stirred tank reactor (CSTR) configured to receive an aqueous effluent of the extraction module of the third SX unit. The third CSTR thus is located downstream of the third SX unit. The third CSTR comprises a dosing device for liquids and heating/cooling means. Suitable continuously 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.

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

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 third metal salt. Suitable crystallizers are known in the art.

The production plant further comprises at least one fourth continuously 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 dosing devices for liquids and heating/cooling means. Suitable continuously stirred tank reactors are known in the art.

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. The production plant further comprises at least one fifth continuously 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 continuously stirred tank reactors are known in the art.

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 fifth solid/liquid separation device comprises a filter press.

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.

Detailed description of the drawing

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

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.

The production plant further comprises at least one first continuously stirred tank reactor (CSTR) 50 which is configured to receive an aqueous effluent 1001 of the extraction module 11 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 sodium carbonate is added to precipitate impurities from the solution. The impurities comprise one or more selected from iron, aluminum, magnesium, calcium, titanium, manganese, residual copper, fluoride, and phosphate. Air is injected into the solution to oxidize any Fe(ll) present to Fe(lll). Iron, aluminum, titanium, and copper precipitate from the solution as hydroxides and/or oxide-hydroxides and/or carbonates, fluorides and/or phosphates,

The production plant further comprises at least one first solid/liquid separation device 100 which is configured to receive an effluent 5001 of the first CSTR 50. In the at least one first solid/liquid separation device 100, the precipitated impurities 10002 are removed from the effluent of the first CSTR 50 by solid/liquid separation, e.g., filtration.

The production plant further comprises at least one second CSTR 60 which is configured to receive an aqueous effluent 10001 from the first solid/liquid separation device 100. The second CSTR 60 comprises a dosing device for liquids and heating/cooling means. In the second CSTR 60, a solution comprising sodium carbonate is added to precipitate residual impurities from the solution.

The production plant further comprises at least one second solid/liquid separation device 110 which is configured to receive an effluent 6001 of the second CSTR 60. In the at least one second solid/liquid separation device 110, solids 11002 are recovered from the effluent 6001 of the second CSTR 60 by solid/liquid separation, e.g., filtration.

The production plant further comprises a second SX unit 20 which is configured to receive an aqueous effluent 11001 of the at least one second solid/liquid separation device 110. The second SX unit 20 comprises an extraction module 21 and a scrubbing and stripping module 22. The aqueous effluent 12001 of the at least one second solid/liquid separation device 120 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 30 comprises an extraction module 31 and a scrubbing and stripping module 32. The aqueous effluent 2001 of 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.

The production plant further comprises a first crystallizer 150 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.

The production plant further comprises at least one third continuously stirred tank reactor (CSTR) 70 which is configured to receive an aqueous effluent 3001 of the extraction module 31 of the third SX unit 30. The CSTR 70 comprises a dosing device for liquids, and heating/cooling means. In the CSTR 70, water removed from the aqueous effluent 3001 , cobalt sulfate and manganese sulfate are added, and subsequently, sodium hydroxide and ammonia are added to precipitate a mixed metal battery material precursor.

The production plant further comprises at least one third solid/liquid separation device 120 which is configured to receive an effluent 7001 of the third CSTR 70. In the at least one third solid/liquid separation device 120, a mixed metal battery material precursor 12002 is recovered from the effluent 7001 of the third CSTR 70 by solid/liquid separation, e.g., filtration.

The production plant further comprises a forth SX unit 40 which is configured to receive an aqueous effluent 12001 of the at least one third solid/liquid separation device 120. The fourth SX unit 40 comprises an extraction module 41 and a scrubbing and stripping module 42. The aqueous effluent 12001 from the third solid/liquid separation device 120 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.

The production plant further comprises a second crystallizer 160 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., lithium sulfate.

The production plant further comprises at least one fourth CSTR 80 which is configured to receive an aqueous effluent 2002 of the scrubbing and stripping module 22 of the second SX unit 20. The fourth CSTR 80 comprises a dosing device for liquids, gas injection means, and heating/cooling means. In the fourth CSTR 80, alkaline solution is added to precipitate manganese carbonate and/or hydroxide.

The production plant further comprises at least one fourth solid/liquid separation device 130 which is configured to receive an effluent 8001 of the fourth CSTR 80. In the at least one fourth solid/liquid separation device 130, manganese carbonate and/or hydroxide 13002 is recovered from the effluent 8001 of the fourth CSTR 80 by solid/liquid separation, e.g., filtration.

The production plant further comprises at least one fifth CSTR 90 which is configured to receive an aqueous effluent 13001 of the at least one fourth solid/liquid separation device 130. The fifth CSTR 90 comprises a dosing device for liquids and heating/cooling means. In the fifth CSTR 90, alkaline solution is added to precipitate metal hydroxides.

The production plant further comprises at least one fifth solid/liquid separation device 140 which is configured to receive an effluent 9001 of the fifth CSTR 90. In the at least one fifth solid/liquid separation device 140, metal hydroxides 14002 are recovered from the effluent 9001 of the fifth CSTR 90 by solid/liquid separation, e.g., filtration.

Examples

Element concentrations in the examples were measured using ICP-OES.

Example 1 (comparative)

An aqueous acid solution obtained from leaching lithium ion battery materials and containing, Ni, Co, Mn, and Li was processed according to the present disclosure, except that sodium hydroxide or sodium carbonate instead of calcium oxide, calcium hydroxide or calcium carbonate was used to adjust the pH in the individual process steps. After solvent extraction of cobalt cations, a solution comprising 27 g/l nickel and 29 g/l sodium was obtained. Water was removed from the solution by evaporation in order to increase nickel concentration in the solution to 96 g/l. However, when nickel concentration reached 51 g/l, precipitation of Na₂Ni(SO4)2 from the solution occurred.

Example 2

Example 1 was repeated using calcium oxide, calcium hydroxide or calcium carbonate to adjust the pH in the individual process steps. After solvent extraction of cobalt cations, water was removed from the solution by evaporation to increase nickel concentration in the solution to 96 g/l. The concentrated solution contained 37.3 g/l sodium.

Table 1 summarizes the composition of the solution of Example 1 before water removal, the hypothetical composition of a concentrate if no precipitation of Na₂Ni(SO4)2 had occurred, and the composition of the concentrated solution obtained in Example 2.

Table 1

Example 3

Solution a.1 : To the concentrated solution obtained in Example 2, commercially available COSO4 and MnSC (both battery grade) dissolved in deionized water were added to obtain a solution containing Ni, Co, and Mn in a molar ratio of 91 :4.5:4.5. Total transition metal concentration in solution a.1 was 1.45 mol/kg. The compositions of the concentrated solution obtained in Example 2 and solution a.1 are listed in Table 2.

Solution [3.1 : 25wt% NaOH dissolved in deionized water.

Solution y.1 : 25wt% ammonia in deionized water.

Synthesis of a mixed metal battery material precursor P-CAM.1

A 3.2 I stirred vessel equipped with baffles and a cross-arm stirrer, and three dosing tubes, one for an aqueous solution (a.1 ), one for solution ([3.1 ) and one for solution (y.1 ), was charged with 3.2 I of deionized water and the temperature of the vessel was set to 45°C. The vessel had a constant nitrogen overflow during all reactions.

The stirrer element was operated at 1100 rpm. Aqueous solution (a.1 ), ([3.1 ) and (y.1 ) were simultaneously introduced into the vessel through the corresponding tubes. The molar ratio of ammonia to transition metal was adjusted to 0.25. Initially, the sum of volume flows was set to adjust the residence time to 10.0 hours. The flow rate of solution ([3.1 ) was adjusted by a pH regulation circuit to keep the pH value in the stirred vessel at a constant value of 12.5 for 1 min of reaction time and thereafter was lowered to 11 .4 for the remaining time of the precipitation reaction.

After 28 h of reaction time, the particle growth was ended by stopping the feed dosing. The slurry obtained was collected and had an average particle diameter (D50) of 3.46 pm and (D90-D10)/D50 of 0.674. A fraction of the slurry was transferred into another 3.2 I stirred tank reactor, which was equipped as described above. The slurry inside the reactor was combined with a solution ([3.1 ) and (y.1 ) at pH-value of 11.4, and an ammonia concentration of 0.5 wt.%. The temperature inside the vessel was set to 55 °C, the stirrer element was operated at 950 rpm and the aqueous solution (a.1 ), ([3.1 ) and (y.1 ) were simultaneously introduced into the vessel through the corresponding tubes and the particles were grown until a particle diameter of 10.6 pm was reached.

The resulting slurry was filtered, washed with deionized water and an aqueous solution of sodium hydroxide (1kg of 25 wt.% aqueous sodium hydroxide solution per kg of solid hydroxide and dried at 120 °C for 12 hours to obtain the precursor P-CAM.1. P-CAM.1 had an average particle diameter (D50) of 10.3 pm, a value of (D90-D10)/D50 of 0.36, a BET surface of 12.6 m²/g, and a lithium-content of 200 ppm. The composition of the precursor P-CAM 1 is shown in Table 3.

Table 2

Table 3

List of reference numerals

10 First SX unit

11 Extraction module of first SX unit

12 Scrubbing and stripping module of first SX unit

20 Second SX unit

21 Extraction module of second SX unit

22 Scrubbing and stripping module of second SX unit

30 Third SX unit

31 Extraction module of third SX unit

32 Scrubbing and stripping module of third SX unit

40 Fourth SX unit

41 Extraction module of fourth SX unit

42 Scrubbing and stripping module of fourth SX unit

50 First CSTR

60 Second CSTR

70 Third CSTR

80 Fourth CSTR 90 Fifth CSTR

100 First solid/liquid separation unit

110 Second solid/liquid separation unit

120 Third solid/liquid separation unit

130 Fourth solid/liquid separation unit

140 Fifth solid/liquid separation unit

150 First crystallizer

160 Second crystallizer

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

1001 Aqueous effluent of extraction module of first SX unit

1002 Aqueous effluent of scrubbing and stripping module of first SX unit

2001 Aqueous effluent of extraction module of second SX unit

2002 Aqueous effluent of scrubbing and stripping module of second SX unit

3001 Aqueous effluent of extraction module of third SX unit

3002 Aqueous effluent of scrubbing and stripping module of third SX unit

4001 Aqueous effluent of extraction module of fourth SX unit

4002 Aqueous effluent of scrubbing and stripping module of fourth SX unit

5001 Effluent of first CSTR

6001 Effluent of second CSTR

7001 Effluent of third CSTR

8001 Effluent of fourth CSTR

9001 Effluent of fifth CSTR

10001 Aqueous effluent of first solid/liquid separation unit

10002 Solids (First impurity precipitate)

11001 Aqueous effluent of second solid/liquid separation unit

11002 Solids (Second impurity precipitate)

12001 Aqueous effluent of third solid/liquid separation unit

12002 Solids (mixed metal battery material precursor)

13001 Aqueous effluent of fourth solid/liquid separation unit

14002 Solids (Manganese hydroxide and/or carbonate)

15001 Aqueous effluent of fifth solid/liquid separation unit

15002 Solids (Metal hydroxides)

Claims

1. A continuous process for for producing a mixed metal battery material precursor 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 calcium carbonate, calcium oxide, calcium hydroxide, barium carbonate, barium oxide, barium hydroxide, and/or MHP, 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 calcium carbonate, calcium oxide, calcium hydroxide, barium carbonate, barium oxide, barium hydroxide, and/or MHP, 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 acidic 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 an organic solvent comprising cobalt cations, and scrubbing and stripping the organic solvent comprising cobalt cations with sulfuric acid to obtain an acidic aqueous solution comprising cobalt cations, h) removing water from the aqueous solution depleted of cobalt cations obtained in step g) to obtain an aqueous solution having a nickel concentration of at least 80 g/l, i) adding cobalt sulfate and manganese sulfate to the solution to obtain a solution comprising nickel, cobalt, and manganese in a predetermined molar ratio, j) adding base and a complexing agent to the solution obtained in step i) and precipitating a mixed metal battery material precursor from the solution, and k) performing a solid/liquid separation of the mixture obtained in step j) to obtain a solid mixed metal battery material precursor and a mother liquor.

2. The process of claim 1 , further comprising l) adjusting the pH of the aqueous solution obtained in step k) 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 an organic solvent comprising lithium cations; and scrubbing and stripping the organic solvent comprising lithium cations with sulfuric acid to obtain an acidic aqueous solution comprising lithium cations.

3. The process of claim 1 or 2, further comprising m) 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, n) removing solids from the mixture obtained in step m), o) optionally, adjusting the pH of the solution obtained in step n) to be in the range of from 10 to 12.5, and precipitating metal hydroxides from the solution, p) optionally, removing solids from the mixture obtained in step o).

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

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

6. The process of any one of claims 1 to 5, wherein copper is recovered from the solution in step a) by solvent extraction and the organic solvent used in solvent extraction is a solution of a 1 :1 mixture of 5-nonyl salicylaldoxime and 2-hydroxy-5-nonyl acetophenone.

7. The process of any one of claims 1 to 5, wherein copper is recovered from the solution in step a) by precipitation of copper sulfide, followed by solid/liquid separation.

8. The process of claim 7, wherein sodium thiosulfate is added in step a) to precipitate copper sulfide.

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

10. The process of any one of claims 1 to 9, wherein the organic 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.

11 . The process of any one of claims 1 to 10, wherein the base used in step j) is at least one alkali hydroxide selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide.

12. The process of any one of claims 1 to 11 , wherein the complexing agent used in step j) is ammonia.

13. 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) (50) configured to receive an aqueous effluent (1001 ) of the extraction module (11 ) of the first SX unit (10), the first 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 (100) configured to receive an effluent (5001) of the first CSTR (50),

(4) at least one second continuous stirred-tank reactor (CSTR) (60) configured to receive an effluent (10001) of the first solid/liquid separation device (100), the second CSTR (60) comprising i. a dosing device for liquids, ii. heating/cooling means,

(5) at least one second solid/liquid separation device (110) configured to receive an effluent (6001) of the second CSTR (60),

(6) a second solvent extraction (SX) unit (20) configured to receive an aqueous effluent (11001) of the second solid/liquid separation device (110), 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 scrubbing and stripping module (22) 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 first crystallizer (150) 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,

(9) at least one third continuous stirred-tank reactor (CSTR) (70) configured to receive an aqueous effluent (3001 ) of the extraction module (31 ) of the third SX unit (30), the third CSTR (70) comprising i. a dosing device for liquids, ii. heating/cooling means,

(10) at least one third solid/liquid separation device (120) configured to receive an effluent (7001) of the third CSTR (70),

(11 ) a fourth solvent extraction (SX) unit (40) configured to receive an aqueous effluent (12001) of the at least one third solid/liquid separation device (120), the fourth SX unit (40) comprising i. an extraction module (41 ), ii. a scrubbing and stripping module (42),

(12) a second crystallizer (160) 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, (13) at least one fourth continuous stirred-tank reactor (CSTR) (80) configured to receive an effluent (2002) of the scrubbing and stripping module (22) of the second SX unit (20), the fifth CSTR (80) comprising i. a dosing device for liquids, ii. heating/cooling means,

(14) at least one fourth solid/liquid separation device (130) configured to receive an effluent (8001) of the fourth CSTR (80),

(15) at least one fifth continuous stirred-tank reactor (CSTR) (90) configured to receive an effluent (13001) of the fourth solid/liquid separation device (130), the fifth CSTR (90) comprising i. a dosing device for liquids, ii. heating/cooling means,

(16) at least one fifth solid/liquid separation device (140) configured to receive an effluent (9001 ) of the fifth CSTR (90).

14. The production plant of claim 13, wherein the first solid/liquid separation device (100), the second solid/liquid separation device (110), the third solid/liquid separation device (120), the fourth solid/liquid separation device (130), and the fifth solid/liquid separation device (140) each comprise a filter press.