WO2024074783A1 - Use of lipophilic derivatives of aminopolycarboxylic acids for the extraction of rare earths from an acidic aqueous solution - Google Patents

Abstract

The invention relates to the use of a lipophilic derivative of an aminopolycarboxylic acid as an extractant to extract at least one rare earth from an acidic aqueous solution. Applications: production of rare earths from concentrates derived from urban ores and, in particular, from concentrates from waste electrical and electronic equipment such as used or discarded NdFeB permanent magnets; production of rare earths from concentrates derived from natural ores or from concentrates derived from residues of natural ores.

Description

USE OF LIPOPHILIC DERIVATIVES OF AMINOPOLYCARBOXYLIC ACIDS FOR THE EXTRACTION OF RARE EARTHS FROM AN ACIDIC AQUEOUS SOLUTION Description TECHNICAL FIELD The invention relates to the field of extraction and recovery of rare earths present in acidic aqueous solutions, in with a view to recycling these rare earths. More specifically, the invention relates to the use of a lipophilic derivative of an aminopolycarboxylic acid as an extractant, to extract one or more rare earths from an acidic aqueous solution. The invention finds particular applications in the production of rare earths from concentrates from “urban ores”, that is to say from “mines” made up of industrial and domestic waste comprising rare earths and, in particular, in the recycling of rare earths present in waste electrical and electronic equipment (also called “WEEE” or “D3E”). More particularly, the invention finds application in the recycling of rare earths contained in used or discarded permanent magnets, and, in particular, in permanent magnets of the Neodymium-Iron-Boron (or NdFeB) type. However, it can also be used to produce rare earths from concentrates from natural ores such as monazites, bastnaesites, apatites or xenotimes, or from concentrates from natural ore residues such as, for example, tin slag. STATE OF PRIOR ART The particular physical and chemical properties of rare earths (scandium, yttrium and lanthanides) currently make them essential chemical elements in many industrial fields: glass and ceramics industries, catalysis, metallurgy, manufacture of permanent magnets , optical devices, phosphors etc. Rare earths are therefore part of the so-called “technological” metals whose supply is strategic. Global demand for rare earths continues to grow and it is estimated that this demand will increase by 50% over the next ten years. However, as the number of countries producing rare earths remains limited – with China currently dominating overall global production of rare earths – there is ultimately a significant risk of a disruption in the supply of rare earths, hence the need to optimize all the ways to produce them. The recycling of rare earths present in used materials is increasingly favored. Recycling makes it possible to reconcile reduced supply risks and environmental challenges linked to mining activities. One of the leading markets in terms of volume and market value for rare earth recycling concerns permanent magnets of the NdFeB type which are found in a certain number of WEEE waste (computer hard drives, audio or video equipment speakers, magnetic devices, etc.). This resource for recycling rare earths has the advantage of including proportions of interesting and recoverable rare earths, typically of the order of 30% by weight. The composition of NdFeB permanent magnets varies depending on the applications of these magnets and the manufacturers, but they typically contain very valuable heavy rare earths (dysprosium and, to a lesser degree, gadolinium, terbium) as well as light rare earths (neodymium and praseodymium in particular). ). The hydrometallurgical route, based on the liquid-liquid extraction technique, is commonly considered as one of the most commercially appropriate routes for recovering rare earths from the environment in which they are found. Hydrometallurgical processes, which are currently used industrially to recover rare earths from an acidic aqueous solution, preferentially employ organophosphorus extractants such as phosphoric acids, phosphonic acids, phosphinic acids, carboxylic acids and alkyl phosphates. . This is, for example, di-2-ethyl-hexylphosphoric acid (or HDEHP), 2-ethylhexylphosphonic acid (or HEH[EHP]), bis(trimethyl-2,4,4-pentyl)phosphinic acid (or Cyanex ^ 272), neo-decanoic acid ( or Versatic ^ 10) and tri-n-butyl phosphate (or TBP). The use of other types of extractants has been proposed in recent years such as that of N,N-dibutylacetamide (see European patent application 3323899, hereinafter reference [1]), that of lipophilic symmetrical diglycolamides such as N,N,N',N'-tetraoctyl-3-oxapentanediamide (or TODGA) (see international application PCT WO 2016/046179, hereinafter reference [2]) and that of amphiphilic asymmetric diglycolamides (see international application PCT WO 2019/197792, hereinafter reference [3]). Furthermore, the idea of developing lipophilic derivatives of aminopolycarboxylic acids emerged in the mid-1970s and then spread over the following years, mainly with the aim of providing compounds intended for medical imaging. Contrast agents have thus been proposed for medical imaging by magnetic resonance comprising a paramagnetic ion, for example Mn ²⁺ , complexed with a lipophilic derivative of ethylenediaminetetraacetic acid (or EDTA) in United States patent 5,762,910, ci -after reference [4], and by a lipophilic derivative of trans-1,2-diaminocyclohexanetetraacetic acid (or CyDTA) in international application PCT WO 2016/135523, hereinafter reference [5]. The use of lipophilic EDTA derivatives, incorporated into a polymer membrane, has also been proposed for the extraction of alkaline earth metals, calcium and magnesium in particular, by Erne et al., Helv. Chem. Acta 1980, 63(8), 2264-2270, hereinafter reference [6]. Finally, it was proposed in United States patent 8,785,691, hereinafter reference [7], to use lipophilic derivatives of EDTA, in solution in 1-octanol, to extract by liquid-liquid extraction the americium(III) and curium(III) selectively with respect to the lanthanides(III) of a raffinate resulting from the implementation of the PUREX spent fuel treatment process. Thus, according to this reference, the lanthanides which represent 15 of the 17 rare earths are not extractable or only very weakly by lipophilic derivatives of EDTA. However, in the context of their work, the inventors noted that contrary to the teaching of reference [7], lipophilic derivatives of amino-polycarboxylic acids and, in particular, EDTA and CyDTA can extract very effectively rare earths and in particular neodymium, praseodymium and dysprosium from acidic aqueous solutions. And it is on these experimental findings that the invention is based. STATEMENT OF THE INVENTION The subject of the invention is therefore the use of a lipophilic derivative of an aminopolycarboxylic acid as an extractant, to extract at least one rare earth from an acidic aqueous solution. This derivative corresponds to the general formula (I) or (II) below: O R2 R ¹ R10

OR ³ R ⁴ R ⁹ (I) (II) in which: m is 0 or 1; R ¹ and R ² , identical or different, represent a hydrogen atom, a linear or branched C1 to C40 alkyl group, a C5 or C6 cycloalkyl group, a monocyclic aryl group, or together form a saturated or unsaturated ring in C5 or C6, optionally substituted one or more times by a hydrogen atom, a linear or branched C1 to C40 alkyl group, a C5 or C6 cycloalkyl group or by a monocyclic aryl group; R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent, independently of each other, a hydrogen atom, a linear or branched C ₁ to C ₄₀ alkyl group, a C ₅ cycloalkyl group or C ₆ or a monocyclic aryl group; X ¹ and X ² , identical to each ^other , and X ³ and X ⁴ , identical to each other but different from X ¹ and linear or branched C ₆ to C ₂₀ alkyl group, a C ₅ or C ₆ cycloalkyl group or a monocyclic aryl group; _X ^{5 and} R ⁹ represents a linear or branched C1 to C40 alkyl group, a C5 or C6 cycloalkyl group, a monocyclic aryl group, a –CH2COOH group or a –CH2- CONHR or –CH2-CONRR' group with R and R' representing a linear or branched C1 to C40 alkyl group, a C5 or C6 cycloalkyl group or a monocyclic aryl group; and R ¹⁰ represents a hydrogen atom or a –COOH group if R ⁹ represents a –CH2COOH group, otherwise R ¹⁰ represents a –COOH group; as an extractant, to extract at least one rare earth from an acidic aqueous solution A1. In the above and what follows, we mean: ^ by “linear or branched C ₁ to C ₄₀ alkyl group”, any alkyl group whose chain is linear or has one or more branches and which comprises at least 1 atom of carbon but which does not include more than 40 carbon atoms; ^ by “C5 or C6 cycloalkyl group”, a cyclopentyl or cyclohexyl group; ^ by "monocyclic aryl group", any cyclic hydrocarbon group which comprises only one cycle and whose cycle meets Hückel's rule of aromaticity and therefore has a number of delocalized π electrons equal to 4n+2; thus, the monocyclic aryl group may in particular be a phenyl group, a tolyl group, a xylyl group, a mesityl group or a benzyl group; ^ by “saturated or unsaturated C5 or C6 cycle”, any cycle which comprises 5 or 6 carbon atoms and which may be saturated or, on the contrary, comprise one or more double bonds, this cycle which may then be an aromatic cycle or not . Furthermore, in what precedes and follows, the expressions “from… to…” and “between… and…” are equivalent and are intended to mean that the limits are included. Likewise, the terms “solution” and “phase” are equivalent and perfectly interchangeable. It goes without saying that, in the general formulas (I) and (II) above, the meanings of R ^{1 to} R ⁸ , of X ^{1 to} we wish to give to the derivative. Thus, in particular, for a high degree of lipophilicity, the presence in these formulas of one or more alkyl groups comprising from 12 to 40 carbon atoms, preferably from 12 to 36 carbon atoms and, even more, from 18 to 24 carbon atoms will be entirely possible. In general formula (I), it is preferred that m is equal to 0. Furthermore, in general formula (I), it is preferred that R ¹ and R ² , identical or different, represent a hydrogen atom, a group linear or branched C1 to C40 alkyl, a C5 or C6 cycloalkyl group, a monocyclic aryl group, or together form a cyclohexyl or phenyl group, optionally substituted one or more times by a hydrogen atom, a linear or branched alkyl group C1 to C40, a C5 or C6 cycloalkyl group or a monocyclic aryl group. Also, the derivative preferably corresponds to the particular formula (Ia), (Ib) or (Ic) below: O R2 X3 X4 R1 O

(Ia) (Ib) (Ic) in which: R ¹ , R ² , R ³ , R ⁴ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ represent, independently of each other, a hydrogen atom, a linear or branched C ₁ to C ₄₀ alkyl group, a C ₅ or C ₆ cycloalkyl group, or a monocyclic aryl group; and X ¹ , X ² , X ³ and X ⁴ are as previously defined. In these _particular formulas, it _{is preferred that} X ^{1 and} or a monocyclic aryl group, in which case X ³ and X ⁴ represent a hydroxyl group. _Even more, it _is preferred that X ^{1 and} an n-octyl, 2-ethylhexyl, n-decyl or n-dodecyl group. Among the derivatives of particular formula (Ia), (Ib) and (Ic), all preference is given to the derivatives of particular formula (Ia) or (Ib) as previously defined. Such derivatives are for example: ^ the derivative of particular formula (Ia) in which R ¹ to R ⁴ all represent a hydrogen atom, X ¹ and X ² represent a group –N(C ₁₀ H ₂₁ ) ₂ while X ³ and X ⁴ represent a hydroxyl group; ^ the derivative of particular formula (Ib) in which R ³ , R ⁴ and R ¹¹ to R ¹⁴ all represent a hydrogen atom, X ¹ and X ² represent a group –N(C ₁₂ H ₂₅ ) ₂ while ³ and X ⁴ represent a hydroxyl group; and ^ the derivative of particular formula (Ib) in which R ³ , ^{R 4} and R ¹¹ to R ^{14 all} represent a hydrogen atom, X ¹ and X ⁴ represents a hydroxyl group. In general formula (II), _{it is} preferred that X ^{5 and} a monocyclic aryl group. Furthermore, it is preferred that X ⁵ and X ⁶ represent a –NRR' group in which R and R' are identical and represent a linear or branched C ₈ to C ₂₀ alkyl group and more particularly, C ₈ to C ₁₂ such as an n-octyl, 2-ethylhexyl, n-decyl or n-dodecyl group. More particularly, it is preferred that X ⁵ and X ⁶ represent a –NRR' group in which R and R' represent a 4-hexyldodecyl group. As for R ⁹ , it preferably represents a –CH ₂ COOH group, in which case R ¹⁰ is advantageously a –COOH group. In accordance with the invention, the rare earth is preferably extracted from the aqueous solution A1 by a liquid-liquid extraction, in which case this extraction comprises at least one bringing the aqueous solution A1 into contact with an organic solution immiscible with water, comprising the derivative in an organic solvent, then separation of the aqueous solution A1 from the organic solution. However, it goes without saying that it is also possible to extract the rare earth from the aqueous solution A1 by solid-liquid extraction, in which case this extraction may in particular comprise bringing this aqueous solution into contact with a solid material insoluble in water and previously impregnated with an organic solution immiscible with water, comprising the derivative in an organic solvent, then separation of the aqueous solution from the solid material. The aqueous solution A1 preferably comprises from 0.1 mmol/L to 0.01 mol/L of an inorganic acid, which is advantageously nitric acid or hydrochloric acid. However, it goes without saying that other inorganic acids such as sulfuric acid or phosphoric acid can also be used. As for the organic solution, it can comprise from 0.01 mol/L to 0.1 mol/L of the derivative, it being understood that the most appropriate concentration is likely to vary from one derivative to another and can easily be determined, for the derivative that one wishes to use, by previously carrying out extraction tests with different concentrations of this derivative. The solvent for the organic solution may be any non-polar solvent in which the derivative, at the concentration at which it is intended to be used, can be solubilized. Organic solvents likely to be suitable include 1,3-diisopropylbenzene, chloroform, 10-undecen-1-ol, methyl isobutyl ketone (or MIBK), 3-heptanone, TBP as well as n-dodecane, alone or mixed with 1-octanol, for example in a volume ratio of 93/7. In accordance with the invention, the extraction of the rare earth from the aqueous solution A1 is preferably followed by a de-extraction of this rare earth from the organic solution obtained at the end of its extraction, which de-extraction advantageously comprises at minus bringing the organic solution obtained at the end of the extraction into contact with an aqueous solution A2, then separating the organic solution from the aqueous solution A2. This aqueous solution A2 may in particular be an acidic aqueous solution having a pH between 0 and 3. Furthermore, to promote the stripping of the rare earth, the aqueous solution A2 may comprise a metal complexing agent such as an aminopolycarboxylic acid of the type nitrilotriacetic acid (or NTA), EDTA, diethylenetriaminepentaacetic acid (or DTPA) or a salt thereof such as a salt of an alkali metal (sodium or potassium in particular), for example at a concentration ranging from 0.005 mol/L to 0 .05 mol/L and, better yet, 0.01 mol/L. In accordance with the invention, the use as it has just been described is preferably implemented to extract neodymium, praseodymium and/or dysprosium from an acidic aqueous solution. This acidic aqueous solution may in particular be a solution resulting from the dissolution in an acidic medium of an urban ore concentrate and, in particular, of a concentrate of D3E waste. As such, it may in particular be a solution resulting from the dissolution in an acid medium of a material in a divided form (powder, fragments, etc.) and resulting from a treatment (for example, demagnetization + grinding as in particular described in international application PCT WO 2014/064587, hereinafter reference [8]) of used or scrapped NdFeB permanent magnets. Other characteristics and advantages of the invention will emerge from the additional description which follows, which relates to experimental tests which made it possible to validate the use of an aminopolycarboxylic derivative as previously defined as a rare earth extractant. It goes without saying that this additional description is given only by way of illustration of the object of the invention and should in no way be interpreted as a limitation of this object. BRIEF DESCRIPTION OF THE FIGURES Figure 1 illustrates the influence of the initial pH of aqueous hydrochloric solutions on the extraction coefficient of neodymium (III), denoted E% _Nd , as observed in extraction tests having been carried out using a lipophilic derivative of EDTA as an extractant, in solution in different solvents. Figure 2 illustrates the influence of the initial pH of aqueous hydrochloric solutions on the distribution coefficient of neodymium(III), denoted DNd, as observed in extraction tests having been carried out using a lipophilic derivative of EDTA as an extractant, in solution in different solvents. Figure 3 illustrates the influence of the initial pH of aqueous nitric solutions on the extraction coefficient of neodymium(III), denoted E%Nd, as observed in extraction tests having been carried out using a lipophilic derivative of EDTA as an extractant, in solution in different solvents. Figure 4 illustrates the distribution isotherm of neodymium(III) as obtained following tests aimed at extracting this element from an aqueous solution comprising 0.01 mol/L of either hydrochloric or nitric acid and using a lipophilic derivative of EDTA as extractant, in solution in 1,3-diisopropylbenzene. Figure 5 illustrates the influence of the initial pH of aqueous hydrochloric solutions on the extraction coefficient, denoted E%M, of neodymium (III), praseodymium (III) and dysprosium (III) as observed in tests extraction having been carried out using a lipophilic derivative of EDTA as extractant, in solution in 1,3-diisopropylbenzene. Figure 6 illustrates the influence of the initial pH of aqueous nitric solutions on the extraction coefficient, denoted E% _M , of neodymium (III), praseodymium (III) and dysprosium(III) as observed in extraction tests having been carried out using a lipophilic derivative of EDTA as extractant, in solution in 1,3-diisopropylbenzene. Figure 7 illustrates the influence of the concentration, denoted [RP2] and expressed in mol/L, of a first lipophilic derivative of CyDTA on the extraction coefficient, denoted E% _M , of neodymium(III), of praseodymium (III) and dysprosium(III) as observed in tests aimed at extracting these three rare earths from an aqueous nitric solution using this derivative as an extractant, in solution in n-dodecane. Figure 8 illustrates the influence of the concentration, denoted [RP4] and expressed in mol/L, of a second lipophilic derivative of CyDTA on the extraction coefficient, denoted E% _M , of neodymium (III), praseodymium (III) and dysprosium(III) as observed in tests aimed at extracting these three rare earths from an aqueous nitric solution using this derivative as an extractant, in solution in n-dodecane. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS The distribution coefficients, the extraction coefficients, the loading capacities and the separation factors which are reported in the examples which follow, were determined in accordance with the conventions in the field of liquid extraction - liquid, namely that: ^ the distribution coefficient between two phases, respectively organic and aqueous, of a metallic element M, denoted D _M and without unit, is determined by the following formula:

^ [M] _^^,é^ in which: [M] _^^^,é^ is the concentration of M in the organic phase at equilibrium (in g/L or mol/L), and [M] _{^ ^,é^} is the concentration of M in the aqueous phase after extraction (in g/L or mol/L); ^ the extraction coefficient of a metallic element M, denoted E%M and without unit, is determined by the following formula: [M] ^% _{^^^,é^ ^} = in which:

[M] _^^^,é^ has the same meaning as previously (in g/L or mol/L), and [M] _^^,^^^^ is the initial concentration of M in the aqueous phase (in g /L or mol/L); ^ the separation factor of a metallic element M1 with respect to a metallic element M2, denoted FSM1/M2 and without unit, is determined by the following formula: ^ _^^

in which: ^ _^^ is the distribution coefficient of M1, and ^ _^^ is the distribution coefficient of M2. EXAMPLE 1: Use of a lipophilic derivative of EDTA The liquid-liquid extraction tests which are reported below were carried out using as extractant, a lipophilic derivative of EDTA, namely the derivative of particular formula (Ia) in which R ¹ , R ² , R ³ and R ⁴ represent a hydrogen atom, X ¹ and X ² represent a –N(C10H21)2 group while X ³ and X ⁴ represent an –OH group. 1 – Synthesis of the derivative: The derivative was previously synthesized by reacting EDTA dianhydride (commercially available) with an excess of didecylamine. To do this, in a 100 mL flask, 1 g (3.9 mmol) of EDTA dianhydride and 2.55 g (8.58 mmol) of didecylamine were dissolved in 33 mL of anhydrous dimethylformamide (or DMF). under nitrogen and heated to 90°C with vigorous stirring for 12 hours. After cooling, the mixture was poured into 330 mL of milli-Q^ water and the precipitate was collected by vacuum filtration. The solid was washed with 50 mL of milli-Q water then dissolved in 150 mL of methanol and evaporated under reduced pressure until a dry residue. The latter was recrystallized from 50 mL of ethyl acetate at 4 °C. The crystals were collected by vacuum filtration, washed with cold ethyl acetate, and dried under high vacuum. 2.6 g of the expected derivative were thus obtained in the form of a white solid (Yield: 78%). 2 – Nd(III) extraction tests: A first series of extraction tests was carried out using: ^ as aqueous solutions, solutions comprising from 0.1 mmol/L to 0.1 mol/L d hydrochloric acid or nitric acid and 0.01 mol/L of neodymium(III) in the form of chloride (in the case of HCl) or nitrate (in the case of HNO3) in water; and ^ as organic solutions, solutions comprising 0.01 mol/L of the derivative in one of the following solvents: 1,3-diisopropylbenzene, chloroform, 10-undecen-1-ol, MIBK, 3-heptanone, TBP as well as an n-dodecane/1-octanol mixture (93/7, v/v). Each test was carried out by putting 2 mL of an aqueous solution and 2 mL of an organic solution (i.e. an O/A ratio of 1) in a tube and subjecting the tube to vigorous shaking (400 rpm) for 30 minutes at room temperature, then centrifugation at 11,000 g for 5 minutes. After which, the concentrations of Nd(III) remaining in the aqueous solutions were determined by inductively coupled plasma emission spectroscopy (or ICP-OES) on aliquots of these solutions after dilution in hydrochloric or nitric acid 1 M. The calibration range was established from ICP standards (PlasmaCAL ^) at 1004 ± 5 µg/mL. The concentrations of Nd(III) present in the organic solutions were deduced from those obtained for the aqueous solutions after a simple material balance. The extraction coefficients, E%Nd, and distribution coefficients, DNd, of Nd(III) were calculated from the concentrations thus determined. Figures 1 to 3 illustrate: ^ Figure 1: the Nd(III) extraction coefficients obtained as a function of the initial pH of the aqueous hydrochloric solutions; ^ figure 2: the distribution coefficients of Nd(III) obtained as a function of the initial pH of the aqueous hydrochloric solutions; And ^ figure 3: the Nd(III) extraction coefficients obtained as a function of the initial pH of the aqueous nitric solutions. Furthermore, Figure 4 illustrates the distribution isotherm of neodymium(III) in the form of a curve which shows the relation to the equilibrium existing between the concentration of Nd(III) in organic solution, denoted [Nd]org ,éq and expressed in g/L, and the initial concentration of this same element in aqueous solution, denoted [Nd]aq,init and expressed in g/L, as obtained for the tests in which neodymium(III) was was extracted from an aqueous solution comprising 0.01 mol/L of hydrochloric acid or nitric acid (pH 2) using as organic solution, a solution comprising 0.015 mol/L in 1,3-diisopropylbenzene. 3 – Nd(III) stripping tests: The stripping tests were carried out using: ^ as organic solutions, the solutions loaded with neodymium(III) as obtained at the end of the extraction tests reported in point 2 above; and ^ as aqueous solutions, solutions comprising 0.01 mol/L of DTPA in water. Each test was carried out following an operating protocol similar to that described in point 2 above. The analysis of the concentrations of Nd(III) in the aqueous and organic solutions after their separation was also carried out as described in point 2 above. These tests showed that it is possible to extract almost all of the neodymium(III) from an organic solution in which it was previously extracted, using an aqueous solution comprising DTPA at a level of 0.01 mol/L. . 4 – Nd(III), Pr(III) and Dy(III) extraction tests: In order to get as close as possible to an acidic leaching environment for NdFeB permanent magnets, a second series of tests The extraction was carried out using: ^ as aqueous solutions, solutions comprising from 0.1 mmol/L to 0.01 mol/L of hydrochloric acid or nitric acid and from 0.01 mol/L to 1, 5 mol/L of each rare earth (neodymium(III), praseodymium(III) and dysprosium(III)) in the form of chlorides (in the case of HCl) or nitrates (in the case of HNO3) in some water ; And ^ as organic solutions, solutions comprising 0.01 mol/L of the derivative in 1,3-diisopropylbenzene or an n-dodecane/1-octanol mixture (93/7, v/v). Each test was carried out following an operating protocol similar to that described in point 2 above. The analysis of the concentrations of the three rare earths in the aqueous and organic solutions after their separation was also carried out as described in point 2 above. Their extraction coefficients, E%M, and distribution coefficients, DM, were calculated from the concentrations thus determined, then the separation factors of neodymium(III) from praseodymium(III) on the one hand , and dysprosium(III) on the other hand, FSNd/Pr and FSNd/Dy, were calculated from the MD thus obtained. The results are illustrated in Figures 5 and 6 and in Table I below which show: Figure 5: the extraction coefficients of Nd(III), Pr(III) and Dy(III) obtained as a function the initial pH of the aqueous hydrochloric solutions for the extractions carried out with the derivative in solution in 1,3-diisopropylbenzene; ^ figure 6: the extraction coefficients of Nd(III), Pr(III) and Dy(III) obtained as a function of the initial pH of the aqueous nitric solutions for the extractions carried out with the derivative in solution in 1.3 -diisopropylbenzene; ^ table I: the separation factors of neodymium(III) with respect to praseodymium(III) on the one hand, and dysprosium(III) on the other hand, obtained for the extractions carried out on aqueous solutions comprising 0 .1 mmol/L of hydrochloric or nitric acid (pH 4) with the derivative in solution in 1,3-diisopropyl-benzene or the n-dodecane/1-octanol mixture (93/7, v/v). 1.3

n-dodecane/1-octanol (93/7, v/v) 1.26 1.07 1.27 1.23 Acid of aqueous HCl HNO solutions ₃

These results show that the derivative makes it possible to extract both neodymium (III), praseodymium (III) and dysprosium (III) from an aqueous hydrochloric or nitric solution having a pH ranging from 2 to 4. They also show that the derivative has more affinity for neodymium(III) than for the other two rare earths, this affinity falling in the order: Nd ^ Pr ^ Dy for the extractions carried out with the derivative in solution in 1,3- diisopropylbenzene while it is in the order: Nd ^ Dy ^ Pr for the extractions carried out with the derivative in solution in the n-dodecane/1-octanol mixture (93/7, v/v). EXAMPLE 2: Use of two lipophilic derivatives of CyDTA The liquid-liquid extraction tests which are reported below were carried out using as extractant, two lipophilic derivatives of CyDTA, in n-dodecane, namely: ^ the derivative of particular formula ⁽ Ib) in which R ³ , ^{R 4} and ^{R 11} to R ¹⁴ represent a hydrogen atom, X ¹ and –OH, called “RP2 derivative” hereinafter; and ^ the derivative of particular formula (Ib) in which R ³ , R ⁴ and R ¹¹ to R ¹⁴ represent a hydrogen atom, X ¹ and X ² represent a group –N(C ₈ H ₁₇ ) ₂ while ³ and X ⁴ represent an –OH group, called “RP4 derivative” below. 1 – Synthesis of the derivatives: The derivatives were previously synthesized by reacting the CyTDA dianhydride with an excess of didodecylamine for the RP2 derivative and dioctylamine for the RP4 derivative. * Synthesis of CyTDA dianhydride: 12.64 g (36.7 mmol) of trans-1,2-diaminocyclohexane tetraacetic acid monohydrate (CyDTA ^H ₂ O) and 11 mL of pyridine were introduced into a single-neck flask of 250 mL. Then, 66 mL of acetic anhydride was added and the mixture was left under stirring overnight. The solution obtained was poured dropwise into 350 mL of diethyl ether and the suspension formed was then filtered through a sintered glass of porosity 3. The precipitate was washed with diethyl ether (3 x 100 mL ) then dried under vacuum. 7.27 g of the expected dianhydride were thus obtained in the form of a yellowish powder (Yield: 69%). * Synthesis of the RP2 derivative: 1 g (3.22 mmol) of the CyDTA dianhydride previously obtained and 2.51 g (2.2 eq., 7.08 mmol) of didodecylamine were introduced into a 100 mL two-neck flask equipped a septum, topped with a refrigerant and placed under an argon atmosphere. Then, 40 mL of DMF were added, the mixture was brought to 60 °C and left stirring overnight. The DMF was then evaporated under vacuum and the residual crude was solubilized in 100 mL of dichloromethane (or DCM) then poured into a 250 mL separatory funnel. The organic phase was washed with 3 M hydrochloric acid solution (2 x 100 mL) then with deionized water (Milli-Q^ - 2 x 100 mL). The organic phase was then dried over sodium sulfate (Na ₂ SO ₄ ) then filtered under reduced pressure. The hydrated salts were rinsed with DCM (3 x 40 mL) and the filtrate was evaporated under reduced pressure. The oily residue was purified by reversed-phase flash chromatography (C18 column) and elution by methanol/isopropanol gradient (from 100/0 to 80/20). 2.19 g of the RP2 derivative were thus obtained in the form of a white paste (Yield: 67%). * Synthesis of the RP4 derivative: 1.43 g of the RP4 derivative in the form of a yellowish oil were obtained by following a protocol to that described for the synthesis of the RP2 derivative except that 1 g (3.22 mmol) of the dianhydride of CyDTA was reacted with 1.71 g (2.2 eq., 7.08 mmol) of dioctylamine and the elution from the C18 column used for purification was carried out by a methanol/water gradient of 95 /5 to 100/0 (Yield: 56%). 2 – Extraction tests: The extraction tests were carried out using: ^ as aqueous solutions, solutions comprising 1 mmol/L of nitric acid and 0.01 mol/L to 0.1 mol/L of neodymium(III), praseodymium(III) and dysprosium(III) as nitrate in water; And ^ as organic solutions, solutions comprising from 0.01 mol/L to 0.1 mol/L of the RP2 derivative or the RP4 derivative, in n-dodecane. Each test was carried out following an operating protocol similar to that described in point 2 of Example I above. The analysis of the concentrations of the three rare earths in the aqueous and organic solutions after their separation was also carried out as described in point 2 of Example I above. Their extraction coefficients, E%M, were calculated from the concentrations thus determined. The results are illustrated in Figures 7 and 8 which present the extraction coefficients thus obtained as a function of the concentrations of RP2 (Figure 7) and RP4 (Figure 8) of the organic solutions. These figures show that, unlike the lipophilic derivative of EDTA tested in Example I above, the two lipophilic derivatives of CyDTA, in solution in n-dodecane, have an identical or almost identical affinity for neodymium (III ), praseodymium(III) and dysprosium(III). These results are extremely interesting because they mean that the invention offers a panel of extractants capable of making it possible to carry out an extraction of neodymium(III) selective with respect to praseodymium(III) and dysprosium(III) – if such an extraction is sought – than an extraction of all three of these rare earths. REFERENCES CITED [1] EP-A-3323899 [2] WO-A-2016/046179 [3] WO-A-2019/197792 [4] US-A-5,762,910 [5] WO-A-2016/135523 [6 ] Erne et al., Helv. Chem. Acta 1980, 63(8), 2264-2270 [7] US-B-8,785,691 [8] WO-A-2014/064587

Claims

Claims 1. Use of a derivative of an aminopolycarboxylic acid, which corresponds to the general formula (I) or (II) below: O _X 2 R3 R2 X6 R1 R10 O

(I) (II) in which: m is 0 or 1; R ¹ and R ² together form a saturated or unsaturated C ₅ or C ₆ ring, optionally substituted one or more times by a hydrogen atom, a linear or branched C ₁ to C ₄₀ alkyl group, a C cycloalkyl group ₅ or C ₆ or by a monocyclic aryl group; R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent, independently of each other, a hydrogen atom, a linear or branched C ₁ to C ₄₀ alkyl group, a C ₅ cycloalkyl group or C ₆ or a monocyclic aryl group; X ¹ and X ² , identical to each ^other , and X ³ and X ⁴ , identical to each other but different from X ¹ and linear or branched C ₆ to C ₂₀ alkyl group, a C ₅ or C ₆ cycloalkyl group or a monocyclic aryl group; _X ^{5 and} _{​ ​ ​} monocyclic aryl; R ⁹ represents a linear or branched C1 to C40 alkyl group, a C ₅ or C ₆ cycloalkyl group, a monocyclic aryl group or a –CH ₂ -CONHR or –CH ₂ -CONRR' group with R and R' representing a linear or branched C ₁ to C ₄₀ alkyl group, a C ₅ or C ₆ cycloalkyl group or a monocyclic aryl group; and R ¹⁰ represents a –COOH group; as an extractant, to extract at least one rare earth from an acidic aqueous solution A1. 2. Use according to claim 1, in which m is 0. 3. Use according to claim 1 or claim 2, in which R ¹ and R ² together form a cyclohexyl or phenyl group, optionally substituted one or more times by an atom hydrogen, a linear or branched C ₁ to C ₄₀ alkyl group, a C5 or C6 cycloalkyl group or a monocyclic aryl group. 4. Use according to any one of claims 1 to 3, in which the derivative corresponds to the particular formula (Ib) or (Ic) below: O X3 X4 O

(Ib) (Ic) in which R ³ , R ⁴ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ represent, independently of each other, a hydrogen atom, a linear or branched C ₁ to C alkyl group ₄₀ , a C ₅ or C ₆ cycloalkyl group, or a monocyclic aryl group. _5. Use _according to claim 4, in which X ^{1 and} ₆ or a monocyclic aryl group, in which case X ³ and X ⁴ represent a hydroxyl group. 6. Use according to claim ₅ , in _which X ^{1 and} ₈ to C ₁₂ , preferably n-octyl, 2-ethylhexyl, n-decyl or n-dodecyl. 7. Use according to any one of claims 4 to 6, in which the aminopolycarboxylic acid derivative is chosen from: ^ the derivative of particular formula (Ib) in which R ³ , R ⁴ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ represent a hydrogen atom, X ¹ and X ² represent a –N(C12H25)2 group and X ³ and X ⁴ represent a hydroxyl group; ^ the derivative of particular formula (Ib) in which R ³ , R ⁴ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ represent a hydrogen atom, X ¹ and X ² represent a group –N(C ₈ H ₁₇ ) ₂ and X ³ and X ⁴ represent a hydroxyl group. 8. Use according to any one of claims 1 to 7, in which the aqueous solution A1 comprises from 0.1 mmol/L to 0.01 mol/L of an inorganic acid, preferably nitric acid or hydrochloric acid. 9. Use according to any one of claims 1 to 8, in which the extraction of the rare earth comprises at least one bringing the aqueous solution A1 into contact with an organic solution immiscible with water, which comprises the derivative in an organic solvent, then separation of the aqueous solution A1 from the organic solution. 10. Use according to claim 9, in which the organic solution comprises from 0.01 mol/L to 0.1 mol/L of the derivative. 11. Use according to claim 9 or claim 10, which further comprises a stripping of the rare earth from the organic solution obtained at the end of the extraction, the stripping comprising at least one bringing the solution into contact organic obtained at the end of the extraction with an aqueous solution A2, then the separation of the organic solution from the aqueous solution A2. 12. Use according to claim 11, in which the aqueous solution A2 comprises a complexing agent, preferably an aminopolycarboxylic acid. 13. Use according to any one of claims 1 to 12, in which the rare earth is chosen from neodymium, praseodymium, dysprosium and their mixtures. 14. Use according to any one of claims 1 to 13, in which the aqueous solution A1 comes from the dissolution in an acid medium of an urban ore concentrate, preferably a concentrate of waste electrical and electronic equipment . 15. Use according to any one of claims 1 to 13, in which the aqueous solution A1 results from the dissolution in an acidic medium of a material in a divided form and resulting from a treatment of permanent Neodymium magnets. Used or discarded Iron-Boron.