Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B59/00—Obtaining rare earth metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/28—Amines
  • C22B3/282—Aliphatic amines
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/32—Carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/41—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds using a solution of normally solid organic compounds, e.g. dissolved polymers, sugars, or the like
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/006—Wet processes
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/006—Wet processes
  • C22B7/007—Wet processes by acid leaching

Definitions

• 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.
• NdFeB Neodymium-Iron-Boron
• 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. .
• 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).
• HDEHP 2-ethylhexylphosphoric acid
• HEH[EHP] 2-ethy
• lipophilic EDTA derivatives incorporated into a polymer membrane
• alkaline earth metals calcium and magnesium
• lipophilic EDTA 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.
• the lanthanides which represent 15 of the 17 rare earths are not extractable or only very weakly by lipophilic derivatives of EDTA.
• 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.
• 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
• 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.
• 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.
• X 1 and an n-octyl, 2-ethylhexyl, n-decyl or n-dodecyl group are preferred.
• 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.
• X 5 and a monocyclic aryl group 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.
• R 9 it preferably represents a –CH 2 COOH group, in which case R 10 is advantageously a –COOH group.
• 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.
• 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.
• an inorganic acid which is advantageously nitric acid or hydrochloric acid.
• other inorganic acids such as sulfuric acid or phosphoric acid can also be used.
• the organic solution 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.
• 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.
• 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.
• 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.
• 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.
• concentration denoted [RP2] and expressed in mol/L
• E% M the extraction coefficient
• 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.
• concentration denoted [RP4] and expressed in mol/L
• E% M the extraction coefficient
• EXAMPLE 1 Use of a lipophilic derivative of EDTA
• 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.
• 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.
• Synthesis of the derivative The derivative was previously synthesized by reacting EDTA dianhydride (commercially available) with an excess of didecylamine.
• 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 ⁇ g/mL.
• ICP-OES inductively coupled plasma emission spectroscopy
• 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.
• Nd(III) 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.
• 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).
• 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.
• 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%).
• 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.

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