Use of organophosphorus compounds for selectively extracting or recovering manganese from an acidic aqueous solution

Abstract

The invention relates to the use of organophosphorus compounds for selectively extracting or recovering manganese from an acidic aqueous solution. These organophosphorus compounds correspond to the following formula (I): (I) wherein R1 is a C4 to C12 linear or branched alkyl group, R2 is a C1 to C8 linear or branched alkyl group and R3 is H or a C1 to C12 linear or branched alkyl group. The invention also relates to the organophosphorus compounds themselves. Uses: recycling of waste from electrical and electronic equipment (WEEE), in particular waste from spent lithium-ion electrochemical batteries with a view to reclaiming the manganese contained in this waste; recovering manganese from natural sources of manganese.

Description

[0001] USE OF ORGANOPHOSPHORUS COMPOUNDS FOR SELECTIVELY EXTRACTING OR RECOVERING MANGANESE FROM AN ACID AQUEOUS SOLUTION

[0002] DESCRIPTION

[0003] TECHNICAL FIELD

[0004] The invention relates to the field of extraction and recovery of manganese present in aqueous acid solutions.

[0005] More specifically, the invention relates to the use of organophosphorus compounds for selectively extracting manganese from an acidic aqueous solution which may comprise, in addition to manganese, other metals such as cobalt, nickel and / or lithium.

[0006] The invention also relates to a process for selectively recovering manganese from such an acidic aqueous solution and using these organophosphorus compounds.

[0007] It also relates to organophosphorus compounds themselves.

[0008] The invention finds particular application in the recycling of waste electrical and electronic equipment (also called "WEEE"), in particular waste from used lithium-ion electrochemical accumulators (more commonly called batteries) with a view to recovering the manganese present in these batteries.

[0009] However, it can also be used to recover manganese from natural manganese sources such as pyrolusite, haussmannite and braunite rocks, and marine manganese nodules.

[0010] STATE OF THE PRIOR ART

[0011] Lithium batteries have become an essential part of our daily lives, as they are used in most everyday portable electronic devices, such as phones and computers. These batteries are also used in electric vehicles, the demand for which has been increasing significantly in recent years, particularly for environmental reasons.

[0012] There are different types of lithium batteries such as lithium-polymer, lithium-iron-phosphate, lithium-manganese, lithium-sulfur or even lithium-ion batteries which are those most commonly used in “consumer” electronic devices.

[0013] Lithium-ion batteries have the advantages of having a high energy density, low self-discharge (i.e. they do not discharge quickly when not in use), a longer lifespan compared to other types of batteries and, finally, requiring little maintenance.

[0014] However, their manufacturing cost remains high, particularly due to the metals of interest contained in the positive electrode materials of these batteries.

[0015] The recycling of used lithium-ion batteries in general, and of the positive electrode materials of these batteries in particular, is therefore a current issue both for the recovery of the metals of interest that they contain and for the protection of the environment.

[0016] The recycling processes for positive electrode materials from used lithium-ion batteries that have been proposed to date are based on two technologies: pyrometallurgy and hydrometallurgy. Pyrometallurgical technology is currently the most widely used, but future processes will primarily use hydrometallurgy, particularly because it is less energy-intensive and better suited to the processing of polymetallic resources.

[0017] Typically, processes based on hydrometallurgy first include a step of producing a concentrate in the form of a powder, called "blackmass", obtained by grinding the positive electrodes of the batteries, a concentrate which, in the case of a lithium-ion battery of the NMC type (for Nickel-Manganese-Cobalt) for example, includes manganese, cobalt, nickel and lithium as metals of interest.

[0018] Then, the blackmass is leached, typically by an acid such as sulfuric acid, and the aqueous solution resulting from this leaching, also called leach juice, is subjected to a series of extractions and back-extractions by liquid-liquid extraction (LLI) to extract and recover the metals of interest.

[0019] ELL is a relatively simple technique to implement, which consists of placing the aqueous medium in which the elements to be extracted are located in contact with an organic solution (or solvent) immiscible with water and comprising one or more extractants in an organic diluent to obtain a transfer of said elements from the aqueous medium to the organic solution. However, the choice of extractant is crucial if the extraction is to have a high yield and be selective with respect to undesirable elements.

[0020] It is known that D2EHPA, or di-2-ethylhexylphosphoric acid, can be used as an extractant to extract manganese and cobalt present in an acid leach juice as described in application WO-A-2022 / 154316 (hereinafter referenced [1]) or in application WO-A-2022 / 147291 (hereinafter referenced [2]).

[0021] It has also been proposed, in application KR-A-10-2324910 (hereinafter referenced [3]) and in application EP-A-4 112 557 (hereinafter referenced [4]), to use 2-ethylhexyl-2-ethylhexylphosphonic acid, known under the trade reference lonquest™ 801, as an extractant for extracting manganese and cobalt from a leach liquor.

[0022] However, the use of these extractants is not entirely satisfactory. In particular, a selective extraction of manganese with respect to cobalt is difficult to achieve with D2EHPA due to the similarity of the pH at which these metals can be extracted with this extractant, which leads to an inevitable loss of cobalt.

[0023] The inventors therefore set themselves the goal of providing extractants which make it possible to very efficiently extract manganese from an acidic aqueous solution and, if this solution includes other metals such as cobalt, nickel and lithium, to extract it selectively with respect to these other metals.

[0024] STATEMENT OF THE INVENTION

[0025] The invention therefore relates, firstly, to the use of an organophosphorus compound of formula (I) below: in which R 1 represents a linear or branched alkyl group, comprising from 4 to 12 carbon atoms, R2 represents a linear or branched alkyl group, comprising from 1 to 8 carbon atoms and R 3 represents a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 12 carbon atoms, as an extractant for extracting manganese from an acidic aqueous solution Al.

[0026] In the above and the following, the term “linear or branched alkyl group, comprising from 4 to 12 carbon atoms”, means any alkyl group (i.e. of formula Cnhbn+i) comprising 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms and the chain of which may be linear or comprise one or more branches.

[0027] By analogy, the term “linear or branched alkyl group, comprising from 1 to 8 carbon atoms”, means any alkyl group comprising 1, 2, 3, 4, 5, 6, 7 or 8 carbon atoms and the chain of which may, here too, be linear or comprise one or more branches.

[0028] Similarly, the term “linear or branched alkyl group, comprising from 1 to 12 carbon atoms”, means any alkyl group comprising 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms and the chain of which may, again, be linear or comprise one or more branches.

[0029] Furthermore, in the above and the following, the expressions "from .... to ...." and "between .... and ...." are equivalent and are intended to mean that the limits are included.

[0030] Similarly, the terms “solution” and “phase” are equivalent and interchangeable.

[0031] In formula (I) above, the linear or branched alkyl group represented by R 1 advantageously comprises from 4 to 10 carbon atoms, preferably from 6 to 9 carbon atoms and, more preferably, 6, 7 or 8 carbon atoms. The linear or branched alkyl group represented by R 2advantageously comprises 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms and, better still, 2, 3 or 4 carbon atoms.

[0032] As for the linear or branched alkyl group represented by R 3 , it advantageously comprises from 1 to 8 carbon atoms.

[0033] Furthermore and independently of the number of carbon atoms included in the alkyl groups represented by R 1 and R 2 , it is preferred that the alkyl group represented by R 1 is a branched group, with one or more branches, and / or that the alkyl group represented by R 2 be a linear group.

[0034] R 3 , for its part, preferably represents a hydrogen atom.

[0035] Examples of organophosphorus compounds meeting these criteria include:

[0036] - the compound of formula (I) in which R 1represents a 2-methyl-4-dimethylpentyl group while R 2 represents an n-butyl group and R 3 represents a hydrogen atom, hereinafter referred to as compound (la),

[0037] - the compound of formula (I) in which R 1 represents a 1-ethyl-pentyl group while R 2 represents an n-butyl group and R 3 represents a hydrogen atom, hereinafter referred to as compound (Ib),

[0038] - the compound of formula (I) in which R 1 represents a 1-ethyl-pentyl group while R 2 represents an ethyl group and R 3 represents a hydrogen atom, hereinafter referred to as compound (the), and

[0039] - the compound of formula (I) in which R 1 represents a 2-methyl-4-dimethylpentyl group while R 2 represents an ethyl group and R 3 represents a hydrogen atom, hereinafter referred to as compound (Id).

[0040] Among these, preference is given to compounds (Ia) and (Ib).

[0041] According to the invention, the manganese is preferably extracted from the Al solution by liquid-liquid extraction, in which case the extraction of the manganese comprises at least one contacting of the Al solution with a water-immiscible organic solution, which comprises the compound in an organic diluent, then a separation of the Al solution from the organic solution. However, it goes without saying that it is also possible to extract the manganese from the Al solution by solid-liquid extraction, in which case this extraction may in particular comprise a contacting of the Al solution with a water-insoluble solid material previously impregnated with a water-immiscible organic solution, comprising the compound in an organic diluent, then a separation of the Al solution from the solid material.

[0042] In any event, the organic solution advantageously comprises from 0.1 mol / L to 1 mol / L, preferably from 0.2 mol / L to 0.5 mol / L and, more preferably, 0.2 mol / L of the compound.

[0043] The diluent of the organic solution is preferably an aliphatic kerosene.

[0044] However, other hydrocarbon-based diluents, preferably aliphatic ones such as n-dodecane, hydrogenated tetrapropylene (TPH) or isoparaffinic diluents of the type marketed by TotalEnergies under the references Isane™ IP-185 and Isane™ IP-175, are also likely to be suitable.

[0045] The Al solution advantageously comprises from 0.1 mol / L to 0.5 mol / L and preferably from 0.2 mol / L to 0.4 mol / L of a strong acid such as sulfuric acid or hydrochloric acid.

[0046] Furthermore, the Al solution and the organic solution are brought into contact in an organic / aqueous volume ratio, or O / Al ratio, which is advantageously between 1 and 5, preferably between 1 and 2.

[0047] Preferably, the pH of the Al solution is adjusted, before and / or during its contact with the organic solution, to a value between 2 and 5, preferably between 2 and 3, for example by adding a base such as sodium hydroxide.

[0048] The invention also relates to a process for recovering manganese present in an acidic aqueous solution Al, the process comprising at least the following successive steps: a) extraction of manganese from the solution Al, the extraction comprising at least one contacting of the solution Al with a water-immiscible organic solution, which comprises an organophosphorus compound of formula (I) above, then a separation of the solution Al from the organic solution; and b) back-extraction of the manganese present in the organic solution obtained at the end of step a), the back-extraction comprising at least one contacting of the organic solution with an acidic aqueous solution A2, then a separation of the organic solution from the solution A2.

[0049] In this process, the Al solution, the organic solution and the O / Al ratio used in step a) are advantageously as previously defined. Furthermore, as previously indicated, the pH of the Al solution can advantageously be adjusted, before and / or during its contact with the organic solution, to a value between 2 and 5, preferably between 2 and 3.

[0050] Solution A2 is a solution which advantageously comprises from 0.1 mol / L to 1.5 mol / L and preferably from 0.3 mol / L to 1.5 mol / L of a strong acid such as sulfuric acid.

[0051] As for the organic / aqueous volume ratio in which the organic solution obtained at the end of step a) and the solution A2 are brought into contact with each other, or O / A2 ratio, it is advantageously between 0.5 and 3 and, preferably, between 0.5 and 1.

[0052] According to the invention, the process may further comprise the treatment of the aqueous solution obtained at the end of step b) to convert the manganese into a salt, for example a sulfate, or into an oxide, for example MnO2.

[0053] To obtain a salt, this treatment may in particular comprise a crystallization step by cooling the aqueous solution so as to reduce the solubility of the manganese and to control the size of the particles of the manganese salt, while, to obtain an oxide, this treatment comprises, for example, an oxidative precipitation in the presence of hydrogen peroxide, permanganate or ammonium persulfate.

[0054] In addition to extracting manganese very efficiently from an acidic aqueous solution, the compounds of formula (I) have been shown to allow excellent separation of manganese from the metals likely to be present in this solution and, in particular, from cobalt, nickel and lithium.

[0055] Also, the use and the recovery process as described above are advantageously implemented to extract / recover the manganese present in an acidic aqueous solution which comprises, in addition to this manganese, cobalt, nickel and / or lithium.

[0056] This acidic aqueous solution may in particular be a solution resulting from an acid leaching of a powder, or blackmass, of a positive electrode material of used lithium-ion batteries, which has possibly previously been freed from metals considered to be impurities (as opposed to the metals of interest such as Mn, Co, Ni and Li) such as iron, aluminum and copper, the positive electrode material preferably being an NMC positive electrode material and, more specifically, an NMC111 positive electrode material, this type of electrode having the characteristics of containing nickel, manganese and cobalt in equivalent proportions.

[0057] In this respect, the manganese recovery process according to the invention is capable of being integrated into a more global process for treating a solution resulting from the acid leaching of a powder of an NMC positive electrode material comprising, in addition to selective recovery of manganese, selective recovery of cobalt, nickel and lithium.

[0058] The invention also relates to an organophosphorus compound of formula (I) as defined above.

[0059] Other characteristics and advantages of the invention will emerge from the additional description which follows.

[0060] It goes without saying that this additional description is given only as an illustration of the subject of the invention and must in no case be interpreted as a limitation of this subject.

[0061] BRIEF DESCRIPTION OF THE FIGURES

[0062] Figure 1 illustrates the influence of pH on the extraction of manganese, cobalt, nickel and lithium from an aqueous solution by a first compound of formula (I), called compound (Ia), and, for comparison, by a state-of-the-art extractant (D2EHPA), the aqueous solution being representative of a leaching liquor of a powder of a positive electrode material NMC of lithium-ion batteries; in this figure, the abscissa axis corresponds to the pH while the ordinate axis corresponds to the extraction yield, noted RM and expressed in %. Figure 2 is a figure similar to Figure 1 but for a second compound of formula (I), called compound (Ib).

[0063] Figure 3 illustrates the influence of the concentration in the organic phase of the compound (la) on the extraction by this compound of manganese, cobalt, nickel and lithium from an aqueous solution representative of a leaching juice of a powder of a positive electrode material NMC of lithium-ion batteries; in this figure, the abscissa axis corresponds to the concentration of the compound (la), noted [(la)] and expressed in mol / L, while the ordinate axis corresponds to the extraction yield, noted RM and expressed in %.

[0064] Figure 4 is a figure analogous to Figure 3 but for compound (Ib).

[0065] Figure 5 illustrates the influence of the O / A volume ratio on the extraction by compound (Ia) of manganese, cobalt, nickel and lithium from an aqueous solution representative of a leaching liquor of a NMC positive electrode material of lithium-ion batteries; in this figure, the abscissa axis corresponds to the O / A volume ratio while the ordinate axis corresponds to the extraction yield, noted RM and expressed in %.

[0066] Figure 6 is a figure analogous to Figure 5 but for compound (Ib).

[0067] Figure 7 illustrates the evolution of the back-extraction yields, noted RM and expressed in %, as obtained during back-extraction tests carried out on an organic phase comprising manganese, cobalt, nickel and lithium, 0.2 mol / L of compound (la) in aliphatic kerosene, as a function of the pH of the aqueous phase used for back-extraction.

[0068] Figure 8 is a figure analogous to Figure 7 but for an organic phase comprising compound (Ib).

[0069] Figure 9 is a schematic diagram of an example of integration of the manganese recovery process of the invention into a more global process for treating an acid leaching juice from a powder of an NMC positive electrode material. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0070] EXAMPLE 1: Synthesis of organophosphorus compounds of formula (I)

[0071] The synthesis of organophosphorus compounds of formula (I) in which R 3 represents a hydrogen atom is carried out in two steps and does not require an additional purification step such as silica gel chromatography, making this synthesis more complex.

[0072] This synthesis is carried out according to the following reaction scheme:

[0073] OO OH OH

[0074] U . P R2 K2CO3I O 1) Me3SiBr, CH2CI29 M O

[0075] R 1 HH^O'R - - R 1 ^ü R 2 - - R IÀ -Ü H

[0076] ' - Without solvent A ° 2) MeOH O

[0077] R 2 9 ' O

[0078] R 2 R 2

[0079] 1 2 in which R 1 and R 2 are as defined above.

[0080] The synthesis of organophosphorus compounds of formula (I) in which R 3 represents a linear or branched C1 to C12 alkyl group, may be analogous to the synthesis as described above, simply completed by a C-alkylation reaction - as known per se - on the carbon atom located alpha to the phosphorus atom of compound 2.

[0081] 1.1.1. Synthesis of intermediate compound 1

[0082] 10 mmol of an aldehyde of formula R 1C(O)H and 10 mmol of a phosphite of formula HP(O)(OR) 2 )2 are introduced into a single-necked flask. The mixture is stirred for 5 minutes at room temperature and then 3 g of anhydrous K2CO3 are added to the flask, while maintaining stirring.

[0083] The progress of the reaction is monitored by thin layer chromatography. Reaction times can vary between 10 minutes and 30 minutes depending on the nature of the R groups. 1 and R 2 . Once the reagents are completely converted, 30 mL of dichloromethane is added to the reaction mixture. The reaction medium is then filtered and K2CO3 is removed by washing with dichloromethane.

[0084] Intermediate compound 1 is isolated from dichloromethane by evaporation of the latter under reduced pressure and used without purification in the next step. 1.1.2. Synthesis of organophosphorus compound 2

[0085] Organophosphorus compound 2 is obtained by selective hydrolysis of intermediate compound 1.

[0086] To do this, the intermediate compound 1 is introduced into a three-necked flask, equipped with a condenser, and then 15 mL of dichloromethane are added. The reaction is carried out under an inert atmosphere, for example under nitrogen. 10 mmol of trimethylsilane bromide (MesSiBr) are then added dropwise and the reaction mixture is stirred for 30 minutes. Afterwards, 2 mL of methanol and then 2 mL of water are added to the reaction mixture, which removes the residual MesSiBr.

[0087] The reaction mixture thus obtained is transferred into a separating funnel and diluted with 40 mL of dichloromethane.

[0088] The organic phase is first washed with 30 mL of 1 mol / L hydrochloric acid solution and then washed twice with 20 mL of distilled water.

[0089] The mixture is left to settle and then the organic phase is separated from the aqueous phase. The organic phase thus recovered is dried over magnesium sulfate (MgSO2) and then subjected to filtration. The dichloromethane is then evaporated under reduced pressure, thus leading to the organosphosphorus compound 2.

[0090] The following are thus synthesized:

[0091] - the compound (the) of formula: by reaction between the aldehyde of formula R 1 C(O)H in which R 1 represents a group -CH2CH(CH3)CH2C(CH3)3 and the phosphite of formula HP(O)(OR 2 )2 in which R 2 represents a group -(CHzhCHs, and whose characterizations are as follows:

[0092] NMR X H (CDCh / TMS, 400 MHz) 6(ppm): 7.26 (s wide, OH), 4.08 (td, J = 6.8 Hz, 2H), 3.98-3.89 (m, 1H), 1.91-1.10 (m, 12H), 0.97 (s, 9H), 0.94 (d, J = 7.0 Hz, 3H), 0.91 (t, J = 7.0 Hz, 3H); NMR 31P (CDCI3 / H3PO4, 100.75 MHz): 6 26.75 (ppm);

[0093] FT-IR: 3320 cm' 1 (y OH), 1025 cm (y P=O);

[0094] MS: m / z calculated for C13H29O4P: 280.18; found: 280.22;

[0095] - the compound (Ib) of formula: by reaction between the aldehyde of formula R 1 C(O)H in which R 1 represents a group -CH(C2HS)(CH2)3CH3 and the phosphite of formula HP(O)(OR 2 )2 in which R 2 represents a group -(CH2)3CH3, and whose characterizations are as follows:

[0096] NMR X H (CDCI3 / TMS, 400 MHz) 6 (ppm): 6.93 (s wide, OH), 4.13 (td, J = 6.8 Hz, 2H), 4.02-3.93 (m, 1H), 1.82-1.24 (m, 13H), 0.95 (t, J = 7.6 Hz, 3H), 0.93 (t, J = 7.6 Hz, 3H), 0.92 (t, J = 7.6 Hz, 3H);

[0097] NMR 31 P (CDCI3 / H3PO4, 100.75 MHz): 5 27.28 ppm;

[0098] FT-IR: 3300 cm 1 (y OH), 1022 cm 1 (y P=O);

[0099] SM: m / z calculated for C12H27O4P: 266.31; found: 266.38;

[0100] - the compound of formula: by reaction between the aldehyde of formula R 1 C(O)H in which R 1 represents a group -CH(C2HS)(CH2)3CH3 and the phosphite of formula HP(O)(OR 2 )2 in which R 2 represents a -CH2CH3 group, and whose characterizations are as follows:

[0101] NMR X H (CDCI3 / TMS, 400 MHz) 5 (ppm): 6.90 (s wide, OH), 4.14 (q, J = 7.0 Hz, 2H), 3.93-3.87 (m, 1H), 1.72-1.27 (m, 9H), 1.31 (t, J = 7.0 Hz, 3H), 0.91 (t, J = 7.0 Hz, 3H), 0.89 (t, J = 7.0 Hz, 3H);

[0102] NMR 31 P (CDCI3 / H3PO4, 100.75 MHz): ô 27.57 ppm; FT-IR: 3334 cm 1 (y OH), 1026 cm 1 (y P=O);

[0103] MS: m / z calculated for C10H23O4P: 238.26; found: 238.17;

[0104] - the compound (Id) of formula: by reaction between the aldehyde of formula R 1 C(O)H in which R 1 represents a group -CH2CH(CH3)CH2C(CH3)3 and the phosphite of formula HP(O)(OR 2 )2 in which R 2 represents a -CH2CH3 group, and whose characterizations are as follows:

[0105] NMR X H (CDCI3 / TMS, 400 MHz) 5 (ppm): 6.06 (s wide, OH), 4.15 (q, J = 6.9 Hz, 2H), 3.96 (m, 1H), 1.91-1.52 (m, 2H), 1.31 (t, J = 6.9 Hz, 3H), 1.28-1.10 (m, 3H), 1.11 and 1.05 (2d, J = 7.0 Hz, 3H), 1.05 (s, 9H);

[0106] NMR 31 P (CDCI3 / H3PO4, 100.75 MHz): 5 26.90 ppm;

[0107] FT-IR: 3328 cm 1 (y OH), 1025 cm 1 (y P=O);

[0108] MS: m / z calculated for C11H25O4P: 252.29; found: 252.11.

[0109] EXAMPLE 2: Use of organophosphorus compounds as extractants

[0110] 2.1 - Extracting properties of compounds in chloride medium

[0111] A first series of extractions is carried out using:

[0112] - as aqueous phases: aliquots of an aqueous solution comprising manganese(ll), cobalt(ll), nickel(ll) and lithium(l) and obtained by solubilizing appropriate quantities of manganese chlorides (MnC^), cobalt (C0Cl2), nickel (NiCh) and lithium (LiCl) in 0.2 mol / L hydrochloric acid (pH = 0.7); and

[0113] - as organic phases: four solutions each comprising one of the compounds (Ia) to (Id), at a concentration of 0.1 mol / L in aliphatic kerosene.

[0114] Prior to the extraction tests, the mass concentrations of each of the metallic elements in the aqueous solution are determined using an Agilent™ MP-AES 4210 emission spectrometer.

[0115] The composition of the aqueous solution is shown in Table I below. Table I

[0116] Sodium hydroxide at 5 mol / L is then added to the aqueous solution until a pH of 5 is obtained.

[0117] For each extraction test, a 10 mL aliquot of the aqueous solution is placed in contact in a tube with 10 mL of one of the organic phases (i.e. an O / A volume ratio of 1) and the whole is subjected to stirring for 15 minutes in a Gerhardt thermostatically controlled shaker (200 rpm) at room temperature (25 °C), then to centrifugation for 2 minutes at 5,000 rpm to separate the aqueous phase from the organic phase.

[0118] If necessary, 5 mol / L sodium hydroxide is added during extraction so that the equilibrium pH of the aqueous phase is equal to 5.

[0119] The recovered aqueous phase is filtered with a hydrophilic Minisart™ filter with a porosity equal to 0.45 pm to eliminate any microdroplets of organic phase stabilized in this aqueous phase and originating from mechanical entrainment.

[0120] Afterwards, the mass concentrations of manganese, cobalt, nickel and lithium remaining in the aqueous phase are measured by emission spectrometry (Agilent™ MP-AES 4210).

[0121] For each of the compounds (Ia) to (Id), the extraction yield of each metallic element, noted RM and expressed in %, is determined by the following equation: in which DM corresponds to the distribution coefficient of the metallic element between the two phases, respectively organic and aqueous, and is itself determined by the following equation: > > [ ]aq,ini [^]aq,fin

[0122] M " [Me in which:

[0123] [M] aq<end is the concentration of the metallic element in the aqueous phase at the end of the extraction, and

[0124] [M] aq< ini est the concentration of the metallic element in the aqueous phase before extraction.

[0125] The extraction yields thus obtained are recorded in Table II below.

[0126] Table II

[0127] This table shows that compounds (Ia) and (Ib) are capable of very strong extraction of manganese from an acidic aqueous solution, with extraction yields greater than 60%, while they weakly extract cobalt, nickel and lithium.

[0128] The manganese extraction yields obtained with compounds (Ic) and (Id) are lower than those obtained with compounds (Ia) and (Ib) but are nevertheless interesting, particularly in view of the inability or near inability of compound (Ic) to extract cobalt, nickel and lithium, and the low extraction yields of these metallic elements obtained with compound (Id).

[0129] 2.2 - Extracting properties of compounds in sulfate medium

[0130] A second series of extraction tests is carried out using: - as aqueous phases: aliquots of an aqueous solution whose composition is representative of a leaching juice of a positive electrode material NMC111 of lithium-ion batteries by sulfuric acid, this aqueous solution being obtained by dissolving appropriate quantities of manganese sulfates (MnSC ), cobalt (COSO ), nickel (NÎSO ) and lithium (U2SO4) in sulfuric acid at 0.35 mol / L (pH = 0.46); and

[0131] - as organic phases: two solutions comprising, one, compound (Ia) and, the other, compound (Ib) in aliphatic kerosene.

[0132] The influence of different parameters on the extracting properties of compounds (Ia) and (Ib) is studied, namely:

[0133] * the pH of the aqueous phases,

[0134] * the concentration of these compounds in the organic phase, and

[0135] * the O / A volume ratio.

[0136] Prior to the extraction tests, the mass concentrations of each of the metallic elements in the aqueous solution are measured by emission spectrometry (Agilent™ MP-AES 4210).

[0137] The composition of the aqueous solution is presented in Table III below.

[0138] Table III

[0139] For each parameter studied, extraction tests are carried out by implementing the following steps:

[0140] - adjustment of the initial pH of the aqueous phase to a desired value;

[0141] - bringing one of the aqueous phases into contact in a tube with one of the organic phases in a specific O / A volume ratio;

[0142] - stirring the biphasic mixture for 15 minutes in a Gerhardt thermostatically controlled stirrer (200 rpm) at room temperature (25 °C) with adjustment of the equilibrium pH of the aqueous phase to the same value as the initial pH; - centrifugation of the biphasic mixture for 2 minutes at 3000 rpm to separate the aqueous phase from the organic phase;

[0143] - filtration of the aqueous phase thus recovered, using a hydrophilic Minisart™ filter with a porosity equal to 0.45 pm;

[0144] - determination of mass concentrations of manganese, cobalt, nickel and lithium remaining in the aqueous phase by emission spectrometry (Agilent™ MP- AES 4210); and

[0145] - calculation of extraction yields of manganese, cobalt, nickel and lithium.

[0146] 2.2.1 - Influence of pH

[0147] Tests aimed at assessing the influence of pH are carried out using:

[0148] - an adjustment of the initial pH to a value ranging from 0.5 to 5,

[0149] - an aqueous phase volume of 5 mL and an organic phase volume of 5 mL (i.e. an O / A volume ratio of 1),

[0150] - a concentration of compound (Ia) or (Ib) in the organic phase of 0.2 mol / L, and

[0151] - an adjustment of the equilibrium pH to the same value as the initial pH.

[0152] For comparison purposes, extraction tests are also carried out with the extractant proposed in references [1] and [2], namely D2EHPA, following the same operating protocol and under the same conditions except that D2EHPA is present in the organic phase at a concentration of 0.8 mol / L.

[0153] The results of these tests are illustrated in Figure 1 for compound (Ia) and in Figure 2 for compound (Ib), these results being, in each of these figures, compared to those obtained for D2EHPA.

[0154] These figures show that identical extraction yields are obtained with compounds (Ia) and (Ib).

[0155] They also show that at a pH of 2.1, manganese is very selectively extracted. Moreover, at this pH, the manganese extraction yield as obtained with D2EHPA is much lower than that obtained with compounds (Ia) and (Ib), even though the concentration in the organic phase is much lower than that of D2EHPA (0.2 mol / L versus 0.8 mol / L).

[0156] Thus, the compounds of formula (I) exhibit properties that make them much more interesting than D2EHPA for the selective extraction of manganese from an acidic aqueous solution, not only in terms of extraction capacity but also in terms of extractant economy, especially since, as mentioned previously, the method of synthesis of these compounds is simple to carry out and does not require purification.

[0157] 2.2.2 - Influence of the concentration of compounds in the organic phase

[0158] Tests aimed at assessing the influence of the concentration of compounds in the organic phase are carried out using:

[0159] - an adjustment of the initial pH to 2.1,

[0160] - an aqueous phase volume of 5 mL and an organic phase volume of 5 mL (i.e. an O / A volume ratio of 1),

[0161] - a concentration of compound (Ia) or (Ib) in the organic phase ranging from 0.2 mol / L to 1 mol / L, and

[0162] - an adjustment of the equilibrium pH to the same value as the initial pH (i.e. 2.1).

[0163] The results of these tests are illustrated in Figure 3 for compound (Ia) and in Figure 4 for compound (Ib).

[0164] These figures show substantially identical results for the two compounds tested, with an increase in the extraction yield of manganese but also in the extraction yields of other metallic elements as the concentration of the compounds in the organic phase increases.

[0165] The use of compound (Ia) or compound (Ib) at a concentration of 0.2 mol / L in the organic phase appears to be particularly interesting because it leads to a manganese extraction yield of around 50% with a high selectivity for this element. 2.2.3 - Influence of the O / A volume ratio

[0166] Tests aimed at assessing the influence of the O / A volume ratio are carried out using:

[0167] - an adjustment of the initial pH to 2.3,

[0168] - an aqueous phase volume of 5 mL and an organic phase volume ranging from 1 mL to 30 mL, i.e. an O / A volume ratio ranging from 0.2 to 6,

[0169] - a concentration of compound (Ia) or (Ib) in the organic phase of 0.2 mol / L, and

[0170] - an adjustment of the equilibrium pH to the same value as the initial pH (i.e. 2.3).

[0171] The results of these tests are illustrated in Figure 5 for compound (Ia) and in Figure 6 for compound (Ib).

[0172] These figures also show substantially identical results for the two compounds tested.

[0173] They also show that from a volume ratio of 4, the extraction yield of manganese reaches approximately 90% but that 20% to 30% of the other metallic elements are co-extracted, whether with compound (Ia) or compound (Ib).

[0174] It therefore appears more interesting to use a lower O / A volume ratio, in particular 1.5, since this allows approximately 70% of the manganese to be extracted in a single step without significantly extracting the other metallic elements.

[0175] 2.3 - Manganese extraction

[0176] Extraction tests are carried out using:

[0177] - as organic phases: aliquots of two organic phases comprising, one, compound (Ia) and, the other, compound (Ib), at a level of 0.2 mol / L in aliphatic kerosene, and having been previously charged with manganese, cobalt, nickel and lithium by extraction of these elements from an aqueous solution representative of a leaching juice of a positive electrode material NMC111 of lithium-ion batteries by sulfuric acid (0.35 mol / L); and

[0178] - as aqueous phases: aqueous solutions of sulfuric acid with concentrations ranging from 0.1 mol / L to 1.5 mol / L. The extractions were carried out following the same procedure as that described in point 2.2 above, using an O / A ratio of 1.6 and adjusting the initial pH and the equilibrium pH to 2.6.

[0179] Table IV below shows the mass concentrations (as measured by emission spectrometry) of manganese, cobalt, nickel and lithium in the aqueous phase, before ([M] aq ,ini) and after extraction ([M] aq ,end), as well as their extraction yield (noted RM), depending on the compound (la) or the compound (Ib).

[0180] Table IV For each back-extraction test, an organic phase loaded with metallic elements is placed in contact in a tube with an aqueous back-extraction phase, in an O / A volume ratio of 1, and the whole is subjected to stirring for 30 minutes in a Gerhardt thermostatically controlled stirrer (200 rpm) at 30°C, then to centrifugation for 2 minutes at 3,000 rpm to separate the aqueous phase from the organic phase.

[0181] The aqueous phase thus recovered is filtered with a hydrophilic Minisart™ filter with a porosity equal to 0.45 pm to eliminate any microdroplets of organic phase stabilized in this aqueous phase. The mass concentrations of manganese, cobalt, nickel and lithium in this aqueous phase are measured by emission spectrometry (Agilent™ MP-AES 4210) and the back-extraction yields of each of the metallic elements are determined.

[0182] The results of these deextraction tests are illustrated in Figure 7 for compound (Ia) and in Figure 8 for compound (Ib).

[0183] These figures show that from a sulfuric acid concentration of 0.3 mol / L, the sulfuric acid concentration of the stripping solution has little influence on the stripping yields of manganese, cobalt, nickel and lithium, these yields remaining almost constant, whether the extractant is compound (Ia) or compound (Ib).

[0184] They also show that a sulfuric acid solution can effectively remove manganese while limiting the removal of other metallic elements.

[0185] As an example, Table V below shows the mass concentrations of manganese, cobalt, nickel and lithium in the organic phase before back-extraction ([M] or g,ini) and in aqueous phase after extraction ([M] aq,fin) as obtained with a 1.5 mol / L sulfuric acid back-extraction solution, depending on compound (Ia) or compound (Ib).

[0186] Table V

[0187] It should be noted that the results reported above were obtained with a single extraction-back-extraction "stage". An increase in the number of stages will make it possible to reduce the content of cobalt, nickel and lithium in the aqueous solution resulting from the last manganese back-extraction stage, while a reduction in the O / A volume ratio will make it possible to concentrate the manganese in this solution and, thereby, facilitate its crystallization in the form of manganese sulfate or its oxidative precipitation in the form of manganese oxide.

[0188] EXAMPLE 3: Integration of the manganese recovery process according to the invention into a more global process for treating an acid leaching juice from a powder of an NMC positive electrode material

[0189] Reference is made to Figure 9 which illustrates a schematic diagram of an example of integration of the manganese recovery process according to the invention - represented in the dotted box in this figure - in a more global process for treating an acid leaching juice from a powder of an NMC positive electrode material.

[0190] As can be seen in Figure 9, this overall process comprises, after a step aimed at removing metallic impurities such as iron, copper and aluminium from the leaching juice, for example by liquid-liquid extraction of copper at a pH between 1 and 2 using an extractant of the Acorga™ type (available for example from Solvay) or of the LIX™ type (available for example from BASF) or by precipitation of iron or aluminium by increasing the pH to a value of 3, the following successive steps:

[0191] - selective recovery of manganese by implementing the process according to the invention with, consequently, extraction of manganese from the leaching juice followed by back-extraction of manganese from the organic phase obtained at the end of the extraction and conversion of the manganese thus back-extracted into a salt, for example MnSÜ4, or into an oxide;

[0192] - a selective recovery of cobalt from the aqueous phase obtained at the end of the manganese extraction of the previous step, this recovery comprising, for example, an extraction of the cobalt from this aqueous phase by means of a water-immiscible organic phase and comprising Cyanex™ 272 as extractant, followed by a back-extraction of the cobalt from the organic phase and a conversion of the cobalt thus back-extracted into a salt, for example CoSO4; - a selective recovery of nickel from the aqueous phase obtained at the end of the manganese extraction, for example by precipitation of the nickel in the form of nickel hydroxide; and

[0193] - selective recovery of lithium from the aqueous phase obtained following nickel precipitation, for example by precipitation of lithium in the form of lithium carbonate.

[0194] The 4 recoverable metals initially present in the leaching juice, including manganese, are thus recovered separately.

[0195] REFERENCES CITED [1] WO 2022 / 154316

[0196] [2] WO 2022 / 147291

[0197] [3] KR 10-2324910

[0198] [4] EP 4112557

Claims

DEMANDS 1. Use of an organophosphorus compound of formula (I): in which: R 1 represents a linear or branched alkyl group, comprising 4 to 12 carbon atoms, R 2 represents a linear or branched alkyl group, comprising from 1 to 8 carbon atoms, and R 3 represents a hydrogen atom or a linear or branched alkyl group, comprising 1 to 12 carbon atoms, as extractant to extract manganese from an acidic aqueous Al solution.

2. Use according to claim 1, wherein R 1 represents a linear or branched alkyl group, comprising 4 to 10 carbon atoms, preferably 6 to 9 carbon atoms and, even better, 6, 7 or 8 carbon atoms.

3. Use according to claim 1 or claim 2, wherein R 2represents a linear or branched group, comprising 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms and, even better, 2, 3 or 4 carbon atoms.

4. Use according to any one of claims 1 to 3, wherein: R 1 represents a branched alkyl group and / or R 2 represents a linear alkyl group and / or R 3 represents a hydrogen atom.

5. Use according to any one of claims 1 to 4, wherein the compound is selected from: the compound of formula (I) in which R 1 represents a 2-methyl-4-dimethylpentyl group, R 2 represents an n-butyl group and R 3 represents a hydrogen atom, the compound of formula (I) in which R 1 represents an 1-ethylpentyl group, R 2 represents an n-butyl group and R 3represents a hydrogen atom, the compound of formula (I) in which R 1 represents an 1-ethylpentyl group, R 2 represents an ethyl group and R 3 represents a hydrogen atom, and the compound of formula (I) in which R 1 represents a 2-methyl-4-dimethylpentyl group, R 2 represents an ethyl group and R 3 represents a hydrogen atom.

6. Use according to claim 5, wherein the compound is a compound of formula (I) in which R 1 represents a 2-methyl-4-dimethylpentyl or 1-ethylpentyl group, R 2 represents an n-butyl group and R 3 represents a hydrogen atom.

7. Use according to any one of claims 1 to 6, wherein the extraction of manganese comprises at least one contacting of the Al solution with an organic solution immiscible with water, which comprises the compound in an organic diluent, and then a separation of the Al solution from the organic solution.

8. Use according to claim 7, wherein the organic solution comprises from 0.1 mol / L to 1 mol / L, preferably from 0.1 mol / L to 0.5 mol / L and, even better, 0.2 mol / L of the compound.

9. Use according to any one of claims 1 to 8, wherein the Al solution comprises from 0.1 mol / L to 0.5 mol / L, preferably from 0.2 mol / L to 0.4 mol / L of a strong acid, preferably sulfuric acid or hydrochloric acid.

10. Use according to any one of claims 7 to 9, wherein the Al solution and the organic solution are brought into contact in an organic / aqueous volume ratio of between 1 and 5, preferably between 1 and 2.

11. Use according to any one of claims 7 to 10, wherein the pH of the Al solution is adjusted, before and / or during the contacting of the Al solution with the organic solution, to a value between 2 and 5, preferably between 2 and 3.

12. A process for recovering manganese from an acidic aqueous solution Al, the process comprising at least the following successive steps: a) extraction of manganese from the solution Al, the extraction comprising at least contacting the solution Al with an organic solution immiscible with water, comprising an organophosphorus compound corresponding to formula (I) as defined in any one of claims 1 to 6, and then separating the solution Al from the organic solution; and b) de-extraction of manganese from the organic solution obtained at the end of step a), the de-extraction comprising at least contacting the organic solution with an acidic aqueous solution A2, and then separating the organic solution from the acidic aqueous solution A2.

13. A process according to claim 12, wherein the organic solution comprises from 0.1 mol / L to 1 mol / L, preferably from 0.1 mol / L to 0.5 mol / L and, even better, 0.2 mol / L of the compound.

14. A method according to claim 12 or claim 13, wherein the Al solution comprises from 0.1 mol / L to 0.5 mol / L and, preferably, from 0.2 mol / L to 0.4 mol / L of a strong acid, preferably sulfuric acid or hydrochloric acid. Tl 15. A method according to any one of claims 12 to 14, wherein, in step a), the Al solution and the organic solution are brought into contact in an organic / aqueous volume ratio of between 1 and 5, preferably between 1 and 2.

16. A method according to any one of claims 12 to 15, wherein the pH of the Al solution is adjusted, before and / or during the contacting of the Al solution with the organic solution, to a value between 2 and 5, preferably between 2 and 3.

17. A process according to any one of claims 12 to 16, wherein the solution A2 comprises from 0.1 mol / L to 1.5 mol / L and, preferably, from 0.3 mol / L to 1.5 mol / L, of a strong acid, preferably sulfuric acid.

18. A process according to any one of claims 12 to 17, wherein, in step b), the organic solution obtained at the end of step a) and solution A2 are brought into contact in an organic / aqueous volume ratio of between 0.5 and 3, preferably between 0.5 and 1.

19. A process according to any one of claims 12 to 18, further comprising a treatment of the aqueous solution obtained at the end of step b) to convert manganese into a salt or an oxide.

20. Use according to any one of claims 1 to 11 or process according to any one of claims 12 to 19, wherein or wherein the Al solution comprises, in addition to manganese, cobalt, nickel and / or lithium.

21. Use or method according to claim 20, wherein the Al solution is obtained from an acid leaching of a powder of a positive electrode material from spent lithium-ion batteries, preferably an NMC positive electrode material.

22. Organophosphorus compound corresponding to formula (I) as defined in any one of claims 1 to 6, with the exception of the compound corresponding to the following formula:

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