CA2904956A1 - Use of compounds comprising amide and phosphonate functions for extracting uranium(vi) from aqueous solutions of sulphuric acid, resulting in particular from sulphuric acid leaching of uranium-comprising ores - Google Patents

Abstract

The invention relates to the use of compounds of general formula (I) below in which: R1 and R2 represent a hydrocarbon group, saturated or unsaturated, linear or branched, C6 to C12; R3 represents H, a hydrocarbon group, saturated or unsaturated, linear or branched, in C1 to C12 and optionally comprising one or more heteroatoms, or a hydrocarbon group, saturated or unsaturated, monocyclic, in C3 to C8 and optionally comprising one or more heteroatoms ; while R4 represents a hydrocarbon group, saturated or unsaturated, linear or branched, in C2 to C8, or a monocyclic aromatic group; as extractants, to extract uranium (VI) from an aqueous solution of sulfuric acid. It also relates to a process which makes it possible to recover the uranium present in an aqueous solution of sulfuric acid resulting from the leaching of a uranium-bearing ore by sulfuric acid and which uses said compounds as extractants. Applications: treatment of uranium ores with a view to recovering the uranium present in these ores.

Description

USE OF COMPOUNDS WITH AMIDE AND PHOSPHONATE FUNCTIONS TO EXTRACT
URANIUM (VI) OF AQUEOUS SOLUTIONS OF SULFURIC ACID, IN PARTICULAR
SULFURIC LIXATION OF URANIUM ORES
DESCRIPTION
TECHNICAL AREA
The invention relates to the field of the extraction of uranium from media aqueous solution containing sulfuric acid.
More specifically, the invention relates to the use of compounds bifunctional functions, comprising both an amide function and a function phosphonate, as extractants, to extract uranium (VI) from an aqueous solution sulfuric acid in which it is present and, in particular, an aqueous solution derived from leaching Uranium ore with sulfuric acid.
The invention also relates to a method for recovering uranium in an aqueous solution of sulfuric acid from the leaching of a uranium ore by sulfuric acid and which uses said compounds as qu'extractants.
The invention finds particular application in the treatment of ores uranifera (uraninite, pitchblende, coffinite, brannérite, carnotite, ...) in view to value the uranium present in these ores.
STATE OF THE PRIOR ART
Uranium minerals (or uranium ores) are extracted from mines, crushed and crushed to the consistency of fine sand, then are subject to an attack, also called leaching, by sulfuric acid (unless their gangue is naturally alkaline, in which case this leaching would require consumption redhibitory sulfuric acid).
Sulfuric acid has been chosen for two reasons: firstly, it is acid strong the cheapest, this acid can be manufactured on the site of the factories of treatment of WO 2014/139869

2 PCT / EP2014 / 054418 uranium ores from sulfur by a process called double catalysis and, on the other hand, its use leads to effluents that are relatively easy to treat because the sulphate ions can be largely eliminated by precipitation with lime.
The attack of each uranium ore is studied on the basis of a optimization of the dissolution efficiency of uranium (VI) compared to quantity of sulfuric acid consumed. Some minerals are easily attacked in stirred tank and only require about 25 kg of pure sulfuric acid per ton of ore while others are attacked only by autoclave and require more than 100 kg sulfuric acid pure per ton of ore.
In all cases, many other elements are also solubilized such as aluminum, iron and silica, which are generally the elements of the gangue, as well as elements that vary from one ore to another, both by their nature only by their quantity, such as molybdenum, vanadium, zirconium, titanium, the copper, nickel and arsenic.
After filtration to remove insolubles, the aqueous solution from leaching with sulfuric acid, which usually contains 0.1 to 10 g / L
uranium, is sent to a purification unit in which it is no only purified but also concentrated either by passing on resins ion exchangers either by liquid-liquid extraction (i.e.
of a phase solvent or organic phase). It then undergoes a pH adjustment and a precipitation, this which makes it possible to obtain a concentrate of uranium of yellow color which one names commonly yellow cake.
This uranium concentrate is filtered, washed, dried, possibly calcined (for obtain uranium sesquioxide U308), before being put in barrels and shipped towards a refinery-conversion plant in which uranium is converted to UF6 from purity nuclear.
To purify by liquid-liquid extraction the aqueous solution resulting from the leaching by sulfuric acid, two processes are used industrially: the process AMEX (from AMine Extraction) and the DAPEX process (from DiAlkylPhosphoric acid Extraction).

WO 2014/139869

3 PCT / EP2014 / 054418 The AMEX process uses, as extractant, a commercial mixture trialkylated tertiary amines whose alkyl chains are C 8 to C 10, example Adogen 364 or Alamine 336, in solution in a hydrocarbon of the type kerosene, possibly added with a heavy alcohol (in C10 to C13) which plays the role of modifier while the DAPEX process uses, as an extractant, a mixture of synergistic di (2-ethylhexyl) phosphoric acid (HDEHP) and tri-n-butyl phosphate (TBP), in solution in a kerosene type hydrocarbon.
None of these methods is completely satisfactory.
Indeed, besides the selectivity towards uranium of the mixture of amines tertiary technologies used in the AMEX process deserves to be improved by particular by compared with molybdenum and vanadium, it turns out that, on the one hand, these amines are degraded during the process by secondary and primary amines by hydrolysis acid ¨
which results in a loss of selectivity of the extraction of uranium ¨
and that else On the other hand, the AMEX process leads to the formation of interfacial disturb the smooth operation of the extractors in which it is used and which are responsible for loss of extractant as well as phase modifier.
As for the DAPEX process, it has the drawbacks of using a extractant which is even less selective for uranium than is the mixture of amines tertiary used in the AMEX process, to have extraction kinetics slow (unlike the AMEX process which has fast extraction kinetics) and limit drastically the terms of uranium removal, once this one extract from aqueous solution from leaching with sulfuric acid.
The development of new extractants more efficient than those currently used in the AMEX and DAPEX processes is therefore an issue important for the uranium mining industry.
In particular, the supply of extractants capable of extracting very effectively uranium from an aqueous solution of phosphoric acid while being more selective for uranium than is the tertiary amine mixture used in the AMEX process and less sensitive to acids than are these amines tertiary WO 2014/139869

4 PCT / EP2014 / 054418 would result in cleaner uranium concentrates, which would facilitate all the way implementation of subsequent refining-conversion processes of these concentrated.
In addition, it would be desirable that these extractants make it possible to obtain a on the other hand, rapid extraction kinetics, taking into account the residence times of phases aqueous and organic phases in the extractors which are only a few minutes, and, on the other hand, a complete separation of the organic phases and aqueous presence, both during the extraction of the uranium and its desextraction of the phase organic.
STATEMENT OF THE INVENTION
The aim of the invention is precisely to propose the use of compounds which satisfy at all these requirements, for the extraction of uranium from aqueous solutions acid sulfuric acid and, in particular, aqueous solutions from leaching of minerals uranifers by sulfuric acid.
The subject of the invention is therefore primarily the use of a compound according to general formula (I) below:

1 \ 1 I \
OH
R2 R3 (I) in which :
Fe and R2, which may be identical or different, represent a hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 6 to 12 carbon atoms;
R3 represents:
¨ a hydrogen atom;
¨ a hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 1 to 12 carbon atoms and optionally one or more heteroatoms;
or ¨ a hydrocarbon group, saturated or unsaturated, monocyclic, comprising 3 at 8 carbon atoms and optionally one or more heteroatoms; while than WO 2014/139869

5 PCT / EP2014 / 054418 R4 represents a hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 2 to 8 carbon atoms, or a monocyclic aromatic group;
as an extractant, to extract uranium (VI) from an aqueous solution acid sulfuric acid in which it is present.
According to the invention, the term hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 6 to 12 carbon atoms, all group alkyl, alkenyl or alkynyl, straight or branched chain, which comprises at least minus 6 carbon atoms but which does not comprise more than 12 carbon atoms.
In a similar way, the term "hydrocarbon group", saturated or unsaturated, linear or branched, comprising from 2 to 8 carbon atoms, all group alkyl, alkenyl or alkynyl, straight or branched chain, which comprises at least minus 2 carbon atoms but which does not include more than 8 carbon atoms.
Furthermore, the term "hydrocarbon group", saturated or unsaturated, linear or branched, comprising from 1 to 12 carbon atoms and optionally one or many heteroatoms, any group consisting of a hydrocarbon chain, linear or branched, which contains at least 1 carbon atom but does not include more than 12 atoms of carbon, whose chain may be saturated or, on the contrary, contain one or many double or triple links and whose chain may be interrupted by one or many heteroatoms or substituted by one or more heteroatoms or by one or many substituents comprising a heteroatom.
In this respect, it is specified that, by heteroatom, we mean any atom other than carbon and hydrogen, this atom typically being a nitrogen atom, of oxygen or sulfur.
Furthermore, the term "hydrocarbon group", saturated or unsaturated, monocyclic, comprising from 3 to 8 carbon atoms and optionally one or many heteroatoms, any cyclic hydrocarbon group which includes only one cycle and whose cycle contains at least 3 carbon atoms but does not understand more of 8 carbon atoms, may be saturated or, on the contrary, have one or many double or triple bonds, and may include one or more heteroatoms or be substituted with one or more heteroatoms or one or more substituents WO 2014/139869

6 PCT / EP2014 / 054418 comprising a heteroatom. Thus, this group can be a group cycloalkyl, cycloalkenyl or cycloalkynyl (for example, a group cyclopropane cyclopentane, cyclohexane, cyclopropenyl, cyclopentenyl or cyclohexenyl), a group saturated heterocyclic (for example, a tetrahydrofuryl, tetrahydro-thiophenyl, pyrrolidinyl or piperidinyl), an unsaturated but unsaturated heterocyclic group aromatic (eg pyrrolinyl or pyridinyl), an aromatic group or a group heteroaromatic.
In this respect, it is specified that, for each aromatic group, all group whose cycle satisfies Hückel's aromaticity rule and presents so a number of delta 7t electrons equal to 4n + 2 (for example, a group phenyl or benzyl), while heteroaromatic is understood to mean any group aromatic as defined but whose cycle includes one or more heteroatoms, this heteroatom or these heteroatoms being typically selected from among the atoms nitrogen, oxygen and sulfur (for example, a furanyl, thiophenyl or pyrrolyl).
According to the invention, in the general formula (I) above, R1 and R2, who may be identical or different, advantageously represent a group alkyl, linear or branched, comprising from 6 to 12 carbon atoms.
Moreover, it is preferred that R1 and R2 be identical to each other and that they both represent a branched alkyl group comprising from 8 to 10 atoms of carbon, the 2-ethylhexyl group being very particularly preferred.
Moreover, in the general formula (I) above, R3 represents advantageously a linear or branched alkyl group comprising from 1 to 12 atoms of carbon, or a monocyclic aromatic group.
More preferably, it is preferred that R3 represents an alkyl group, linear or branched, comprising from 6 to 10 carbon atoms, especially 2-ethylhexyl or n-octyl or a phenyl group.
Finally, in the general formula (I) above, R4 preferably represents a alkyl group, linear or branched, comprising from 2 to 8 carbon atoms and, better again, from 2 to 4 carbon atoms such as an ethyl, n-propyl, isopropyl, WO 2014/139869

7 PCT / EP2014 / 054418 n-butyl, sec-butyl, isobutyl or tert-butyl, ethyl groups, isopropyl, n-butyl and isobutyl being very particularly preferred.
Compounds of general formula (1) above which exhibit these characteristics include:
¨ n-butyl 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate, which corresponds to the general formula (1) above in which R1 and R2 represent each one a 2-ethylhexyl group, R3 represents an n-octyl group while R4 represents a n-butyl group;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) isopropyl nonylphosphonate, which corresponds to the general formula (1) above in which R1 and R2 represent each one a 2-ethylhexyl group, R3 represents an n-octyl group while R4 represents a isopropyl group;
the 1- (N, N-di-2-éthylhexylcarbamoy1) -2-éthylhexylphosphonate isopropyl, which corresponds to the general formula (1) above in which Fe, R2 and R3 each represent a 2-ethylhexyl group while R4 represents a group isopropyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) isobutyl nonylphosphonate, which corresponds to the general formula (1) above in which R1 and R2 represent each one a 2-ethylhexyl group, R3 represents an n-octyl group while R4 represents a isobutyl group;
the 1- (N, N-di-2-éthylhexylcarbamoy1) -2-éthylhexylphosphonate isobutyl, which corresponds to the general formula (1) above in which Fe, R2 and R3 each represent a 2-ethylhexyl group while R4 represents a group isobutyl;
¨ (N, N-di-n-octylcarbamoyl) isobutyl nonylphosphonate, which responds to the general formula (1) above in which Fe, R2 and R3 represent each a group n-octyl while R4 is isobutyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) -2-ethylhexylphosphonate n-butyl, which corresponds to the general formula (1) above in which Fe, R2 and R3 WO 2014/139869

8 PCT / EP2014 / 054418 each represent a 2-ethylhexyl group while R4 represents a group n-butyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) ethyl nonylphosphonate, which corresponds to the general formula (I) above in which R1 and R2 represent each one a 2-ethylhexyl group, R3 represents an n-octyl group while R4 represents a ethyl group; and ¨ n-butyl (N, N-di-n-octylcarbamoyl) nonylphosphonate, which responds to the general formula (I) above in which Fe, R2 and R3 represent each a group n-octyl while R4 is n-butyl.
Of these compounds, 1- (N, N-di-2-ethyl) is particularly preferred.
hexylcarbamoyl) n-butyl nonylphosphonate and 1- (N, N-di-2-éthylhexylcarbamoyI) -isopropyl nonylphosphonate.
The compounds which correspond to the general formula (I) above in which Fe, R2 and R4 are as previously defined and R3 represents an atom hydrogen can in particular be synthesized by a method which comprises:
¨ the reaction of an amine of formula HNR1R2 in which R1 and R2 are such than previously defined with a compound of formula (II) below:
XLX (ii) in which X represents a halogen atom, for example a chlorine atom or bromine, to obtain a compound of formula (III) below:
Ri LX
,NOT
R2 (III) wherein Fe, R2 and X are as previously defined;
The reaction of the compound of formula (III) above with a compound of formula HP (0) (OR4) 2 in which R4 is as previously defined, for obtain a compound of formula (IV) below:

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9 PCT / EP2014 / 054418 R'l Lif-OR4 , N \ OR4 R2 (IV) wherein Fe, R2 and R4 are as previously defined; and ¨ treating the compound of formula (IV) above with a strong base.
These steps correspond to the steps noted A, B and C in Figure 1 attached in Annex.
As for the compounds which correspond to the general formula (I) above in which Fe, R2 and R4 are as previously defined and R3 represents either a group hydrocarbonaceous, saturated or unsaturated, linear or branched, comprising from 1 to 12 atoms of carbon and possibly one or more heteroatoms, a group hydrocarbon, saturated or unsaturated, monocyclic, comprising from 3 to 8 carbon atoms and possibly one or more heteroatoms, they can be synthesized by a process which comprises:
The reaction of an amine of formula HNR1R2 in which R1 and R2 are such than previously defined with a compound of formula (II) below:
XLX (ii) in which X represents a halogen atom, for example a chlorine atom or bromine, to obtain a compound of formula (III) below:
Ri LX
,NOT
R2 (III) wherein Fe, R2 and X are as previously defined;
The reaction of the compound of formula (III) above with a compound of formula HP (0) (OR4) 2 in which R4 is as previously defined, for obtain a compound of formula (IV) below:

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10 PCT / EP2014 / 054418 R'l L 11C) R4 , N \ OR4 R2 (IV) wherein Fe, R2 and R4 are as previously defined;
The reaction of the compound of formula (IV) above with a composed of R 3 -Y in which Y represents a halogen atom, for example a atom of chlorine or bromine, to obtain the compound of formula (V) below:

r R2,11 \ OR4 R3 (V) wherein Fe, R2, R3 and R4 are as previously defined; and ¨ treating the compound of formula (V) above with a strong base.
These steps correspond to the steps noted A, B, D and E in the attached FIG.
in annex.
Step A is, for example, carried out in the presence of triethylamine in a organic solvent of the dichloromethane type.
Steps B and D are, for example, carried out in the presence of n-butyllithium and 2,2'-bipyridine, or sodium hydride and 2,2'-bipyridine, in a solvent tetrahydrofuran type organic, while steps C and E are, for example, example, made using potash as a strong base, in a compound solvent of water and of dimethylformamide.
Typically, the compound of general formula (I) above is used for extract the uranium (VI) from the aqueous sulfuric acid solution by liquid extraction liquid, that is to say by bringing this aqueous solution into contact with a phase organic compound comprising said compound and then separating this aqueous solution from the sentence in which case this organic phase preferably comprises the composed in solution, at a concentration of 0.01 to 1 mol / L, in an organic diluent, advantageously of the aliphatic type such as n-dodecane, tetrapropylene hydrogen WO 2014/139869

11 PCT / EP2014 / 054418 (TPH) or kerosene, for example that marketed by the company TOTAL
under the commercial reference Isane IP-185.
According to the invention, the aqueous solution from which the uranium (VI) is extracted is advantageously an aqueous solution of sulfuric acid which comes from the leaching of a uranium ore by sulfuric acid, in which case this aqueous solution typically comprises from 0.1 to 10 g / L of uranium, from 0.1 to 2 mol / L of ions sulphate acidity of 0.01 to 0.5 mol / L.
The invention also relates to a process for recovering uranium present in an aqueous solution of sulfuric acid resulting from the lixiviation an ore uraniferous sulfuric acid, which process comprises:
(a) the extraction of uranium, in oxidation state VI, from aqueous solution sulfuric acid, by bringing this solution into contact with a phase organic comprising a compound as defined above, then separation from said solution aqueous and of said organic phase; and b) the extraction of uranium (VI) present in the organic phase obtained at the end of step a), by contacting this organic phase with a aqueous phase comprising a carbonate, for example ammonium or sodium, then separating said organic phase and said aqueous phase.
In this process, the compound is preferably used in solution at a concentration of from 0.01 to 1 mol / L, in an organic diluent, advantageously type aliphatic such as n-dodecane, TPH or isane.
The aqueous solution of sulfuric acid, which is used in step a), comprises preferably from 0.1 to 10 g / l of uranium and from 0.1 to 2 mol / l of ions sulphate acidity from 0.01 to 0.5 mol / L, while the aqueous phase comprising the carbonate, which is used in step b), preferably comprises from 0.1 to 1 mol / L of carbonate.
Moreover, in accordance with the invention, the volume ratio between the phase organic and sulfuric acid solution, which are used in step a), and / or the report volume between the organic phase and the aqueous phase comprising the carbonate, which are used in step b), are (are) adjusted so that the aqueous phase obtained at the end of step (b) has a concentration of uranium that makes it possible to precipitate WO 2014/139869

12 PCT / EP2014 / 054418 subsequently this uranium under good conditions, that is to say a concentration in uranium typically 40 to 100 g / L.
It is possible to favor a concentrated extraction (step a)) or, at contrary, a de-extraction (step b)) concentrating, even a situation intermediate, each of these steps contributing to the concentration of uranium up to the target value.
Thus, the volume ratio between the organic phase and the aqueous solution sulfuric acid may, for example, be less than or equal to 1 and better again, understood between 0.2 and 1, while the volume ratio between the organic phase and the phase aqueous solution comprising the carbonate may, for example, be greater than 1, for induce to a concentration of uranium in the organic phase in step a) and a concentration uranium in aqueous phase in step b).
According to the invention, step a) of the method may furthermore comprise washing the organic phase after separation from the aqueous solution, to eliminate of this phase:
¨ either the traces acid that may have been co-extracted with uranium, in which case this washing is preferably carried out by contacting the organic phase with an aqueous phase consisting solely of water, then separation from said phase organic and of said aqueous phase;
¨
either, depending on the level of purity required, traces of unwanted cations such as molybdenum, vanadium or titanium, which may have been extracted with uranium, in which case this washing is preferably carried out by phase contact organic material with an aqueous phase comprising sulfuric acid or a complexing strong impurities such as oxalate or citrate, for example ammonium or of sodium, and then separating said organic phase and said aqueous phase.
Other features and advantages of the invention will become more apparent reading of the description supplement which follows, which relates to examples of synthesis of useful compounds according to the invention and demonstration of their properties.
Of course, these examples are only given as an illustration of the object of the invention and in no way constitute a limitation of this object.

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13 PCT / EP2014 / 054418 BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 illustrates the steps of the methods for synthesizing useful compounds according to the invention.
Figure 2 illustrates the isotherm of the extraction of uranium (VI) by a compound useful according to the invention.
Figure 3 illustrates the kinetics of the extraction of uranium (VI) by a compound useful according to the invention (curve A) and by Alamine 336 (curve B).
Figure 4 illustrates the evolution of the distribution coefficient of uranium, note Du, as a function of the molar concentration of total sulphates (denoted [SO4 totals] and expressed in mol / L) of the solution from which this uranium is extracted by a compound useful according to the invention and this, for three different initial concentrations of H + ions of this solution: 0.2 N (curve A), 0.35 N (curve B) and 0.5 N (curve C).
DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

1.1 ¨ Synthesis of n-1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate butyl:
N-Butyl 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate, noted DEHCNPB, which corresponds to the general formula (I) above in which RI- = R2 = 2-ethyl hexyl, R3 = n-octyl, R4 = n-butyl, is synthesized using the steps A, B, D
and E shown in Figure 1.
Step A: Synthesis of 2-chloro-N, N-di-2-ethylhexylacetamide 7.46 ml (2 eq.) Of stirring and nitrogen are introduced into a three-necked flask.
bis (2-ethylhexyl) amine, 50 mL of dichloromethane and 3.5 mL (1 eq) of triethylamine, that cooled to -30 C with a dry ice / acetone bath. Then, we add drip 2 mL (1 eq.) Of chloroacetyl chloride and the reaction mixture is left during 3 hours at room temperature. After that, it is poured on 50 mL of water distilled, decanted and extracted with 50 mL of dichloromethane. The dichloromethane phases are washed with 50 ml of distilled water, dried over magnesium sulphate, filtered and evaporated to dryness WO 2014/139869

14 PCT / EP2014 / 054418 the rotary evaporator. The 7.26 g of yellow oil thus obtained are subject to a column chromatography on silica gel (80 g - 63-200 μm) granulometry) with a dichloromethane / methanol mixture 98/2, v / v, as eluent.
There is thus obtained 7.20 g of 2-chloro-N, N-di-2-ethylhexylacetamide under pale yellow oil (Yield: 92%), of which the characterizations by 1-NMR
H and 1-3C as well only by mass spectrometry are given below.
1H NMR (400MHz, CDCl3) δ (ρm): 4.08 (2H, s, CH2Cl); 3.23-3.28 (2H, m, NCH2); 3.20 (2H, d, J = 7.5 Hz, NCH 2); 1.76-1.65 (1H, m, NCH 2 CH); 1.64-1.52 (1H, m, NCH2CH); 1,40-1.15 (16H, m, CH 3 (CH 2) 3 CH (CH 2 CH 3) CH 2 N); 0.95-0.78 (12H, m, CH3) =
13 C NMR (100.13 MHz, CDCl3) δ (MPm): 166.64 (C = O); 51.27 (NCH 2); 48.3 (NCH2); 41.17 (CH2Cl); 38.10 (CH); 36.40 (CH); 30.16 (NCH 2 CH (Et) CH 2 (CH 2) 2 CH 3); 30,00 (NCH 2 CH (Et) CH 2 (CH 2) 2 CH 3); 28.40 (NCH 2 CH (Et) -CH 2 CH 2 CH 2 CH 3);
28.24 (NCH2CH (and) CH2CH2CH2CH3); 23.49 (-CHCH2CH3); 23.35 (-CHCH2CH3); 22.65 (NCH2CH (And) -CH2CH2CH2CH3); 22.62 (NCH 2 CH (Et) CH 2 CH 2 CH 2 CH 3); 13.67 (-CH 2 CH 2 CH 3);
13.63 (-CH2CH2CH3); 10.49 (-CHCH2CH3); 10.20 (-CHCH2CI-13) =
ESI +: [M + 11] = 318, [Mi-Na] = 340, [2M + Na] = 657 Step B: Synthesis of 1- (N, N-di-2-ethylhexylcarbamoyl) methylphosphonate di-n-butyl 1 ml (1 eq.) Of diethyl ether are introduced into a three-necked flask under stirring and under nitrogen.
not-butyl phosphite, some crystals of 2,2'-bipyridine and 50 mL of tetrahydrofuran, that cooled to -50 C with a dry ice / acetone bath. Then, we add drip 4.6 mL (1.5 eq) of a solution of n-butyllithium at 1.6 mol / L in hexane. We obtain a clear red reaction mixture. 1.95 g are then added dropwise (1.25 eq.) 2-chloro-N, N-di-2-ethylhexylacetamide. A reaction mixture is obtained yellow who is left overnight at room temperature. After which, it is poured on 100 mL
of distilled water and acidified by the addition of HCl N in sufficient quantity to get a pH
acid. The whole is extracted with 2 times 50 ml of ethyl ether. The phases ethereal are washed with twice 50 ml of distilled water and 50 ml of water saturated with NaCl, dried on magnesium sulphate, filtered and evaporated to dryness on a rotary evaporator.
2.69 g WO 2014/139869

15 PCT / EP2014 / 054418 of yellow oil thus obtained are subjected to chromatography on a column silica (125 g - 63-200 um particle size) using a mixture cyclohexane / ethyl acetate of ethyl 8/2, v / v, as eluent.
1.03 g of 1- (N, N-di-2-ethylhexylcarbamoyl) methyl are thus obtained.
di-n-butyl phosphonate in the form of a colorless oil (Yield: 44%) the characterizations by 1H, 13C and 31P NMR as well as by mass spectrometry are given below.
1 H NMR (400 MHz, CDCl 3) δ (ppm): 4.18-4.04 (4H, m, OCH 2); 3.37-3.20 (4H, m, NCH2);
3.07 (2H, d, J = 22Hz, COCH2P); 1.78-1.51 (6H, m, OCH2CH2, CH); 1.47 to 1.14 (20H, m, OCH2CH2CH2, C1-13 (CH2) 3CH (CH2CH3) CH2N); 0.99-0.82 (18H, m, CHA =
13 C NMR (100.13 MHz, CDCl3) δ (ppm): 165.15 (C = O); 66.15 (d, 2 Pdc = 6.6 Hz);
52.26 (NC2); 48.86 (NCH 2), 38.58 (CH); 36.98 (CH); 33.61 (d, 1 Jpc = 133 Hz, CH2P) ; 30,52 and 30.27 (NCH 2 CH (Et) CH 2 (CH 2) 2 CH 3); 30,17 (OCH2CH2CH2CH3); 28.81 and 28.67 (NCH 2 CH (Et) CH 2 CH 2 CH 2 CH 3), 26.86 (OCH 2 CH 2 CH 2 CH 3); 23.83 and 23.39 (-CHCH2CH3);
23.11 and 23.03 (NCH 2 CH (Et) CH 2 CH 2 CH 2 CH 3); 18.72 (OCH 2 CH 2 CH 2 CH 3); 14.12 and 14.03 (OCH2CH2CH2CH3); 13.61 (CH 2 CH 2 CH 3); 10.91 and 10.51 (-CHCH2C1-13).
31 P NMR (162 MHz, CDCl 3, decoupling 1H) O (ppm): 22.03 (s, P = 0) ESI +: [M + 11] = 476, [2M + Na] = 973 Step D: Synthesis of 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate from n-butyl 3.5 g (1 eq.) Of stirring and nitrogen are introduced into a three-necked flask.
Di-n-butyl 1- (N, N-di-2-ethylhexylcarbamoyl) methylphosphonate, 50 mL of tetra-hydrofuran and some crystals of 2,2'-bipyridine, which is cooled to -50 C with a dry ice / acetone bath. Then, bromooctane is added dropwise. We gets a clear red reaction mixture which is left for 20 minutes at this temperature. 3.92 mL (1.5 eq) of a solution are then added dropwise.
of n-butyllithium at 1.6 mol / L in hexane. The dry ice / acetone bath is withdrawn and the reaction rises slowly to room temperature. The reaction mixture is then heated overnight at 60 C. After which, the reaction mixture is poured on 100 mL

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16 PCT / EP2014 / 054418 of distilled water and acidified by the addition of HCl N in sufficient quantity to get a pH
acid. It is extracted twice with 50 ml of ethyl ether. The ethereal phases are washed with 2 times 50 ml of distilled water and 50 ml of water saturated with NaCl, dried over sulphate magnesium, filtered and evaporated to dryness on a rotary evaporator. 3.45 g yellow oil thus obtained are subjected to chromatography on a silica column (125 g - 63-200 μm particle size) using a cyclohexane / ethyl acetate mixture 9/1, v / v, as an eluent.
1.1 g of 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate are thus obtained.
di-n-butyl in the form of a colorless oil (Yield: 44%), characterizations by NMR 11-1, 13C and 31P and by mass spectrometry are given below.
after.
1H NMR (400MHz, CDCl3) δ (ppm): 0.81-0.93 (m, 21H, CH3); 1.17 - 1.42 (m, 32H, CH2, OCH2CH2CH2CH3); 1.59-1.66 (m, 5H, CHCH2N, OCH2CH2CH2CH3); 1.69 - 1.84 (m, 2H, CHCH2N, C7H15CH2CH (CO) P); 2.02 - 2.13 (m, 1H, C7H15CH2CH (CO) P); 2.80 - 2.92 (m, 1H, CH2N); 2.95 - 3.03 (m, 1H, CH 2 N); 3.14- 3.22 (m, 1H, COCH (Oct) P); 3.43 -3.55 (m, 1H, CH2N); 3.62 - 3.78 (m, 1H, CH 2 N); 3.96 -4.11 (m, 4H, OCH 2 CH 2 CH 2 CH 3) =
13 C NMR (100 MHz, CDCl3) δ (ppm): 10.4; 10.7; 10.9; 11.0 (CH3); 13.8 (OCH2CH2CH2CH3); 14.2; 14.3 (CH3); 18.9 (OCH 2 CH 2 CH 2 CH 3); 22.8; 23.2; 23.3;
23.7;
23.9; 24.0; (CH2); 28.2 (C7H15CH2CH (CO) P); 28.8; 28.9; 29.0; 29.1; 29.4;
29.5; 29.8;
29.9; 30.4; 30.5; 30.7; 30.8; 32.0 (CH2); 32.7; 32.8 (d, J = 6.5 Hz, OCH2CH2CH2CH3);
37.2; 37.3; 37.4; 39.2; 39.3; 39.5; 39.6 (CHCH2N); 41.9; 43.2 (d, J =
131.0 Hz, COCH (Oct) P); 50.0; 50.2; 50.9; 51.1; 51.9; 52.0; 52.6; 52.7 (CH2N); 66.1 (d, J = 6.5 Hz, OCH2CH2); 66.3 (d, J = 6.5 Hz, OCH 2 CH 2); 168.5 (d, J = 5.0 Hz, C = O).
31 P NMR (160 MHz, CDCl3) δ (ppm): 24.6.
ESI +: [M + H] = 588, [Mi-Na] = 610, [2M + Na] = 1197 Step E: Synthesis of n-1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate butyl A 0.4 g (1 eq) of CEM DiscoverTM microwave reactor is charged to Di-n-butyl 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate, 5 mL of water distilled 5 mL of dimethylformamide and 0.23 g (6 eq) of potash, which is heated to 150 VS

WO 2014/139869

17 PCT / EP2014 / 054418 for 15 hours. After which, the reaction mixture is poured on 100 ml water distilled and acidified by addition of N HCl in sufficient quantity to obtain an acidic pH. he is extracted with 2 times 50 ml of ethyl ether. The ethereal phases are washed with 2 times 50 ml of distilled water, dried over magnesium sulphate, filtered and evaporated to dryness the rotary evaporator. The 0.34 g of oil thus obtained are subjected to a chromatography on a silica column (17 g - 63-200 μm granulometry) using a mixed dichloromethane / methanol 97/3, v / v, as eluent.
0.14 g of 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate are thus obtained.
n-butyl in the form of a colorless oil (yield: 39%), characterizations by 1H, 13C and 31P NMR as well as by mass spectrometry are given below.
after.
1H NMR (400MHz, CDCl3) δ (PPm): 0.83-0.94 (m, 15H, CH3); 1.20 - 1.41 (m, 30H, CH2, OCH2CH2CH2CH3); 1.59 - 1.73 (m, 4H, OCH 2 CH 2 CH 2 CH 3, C 7 H 15 CH 2 CH (CO) P); 1.85 -2.06 (m, 2H, CHCH2N); 3.07-3.21 (m, 3H, CH2N, COCH (Oct) P); 3.24 - 3.50 (m, 2H, CH2N);
3.98 -4.10 (m, 2H, OCH 2 CH 2 CH 2 CH 3); 9.34 (s, 1H, OH).
13 C NMR (100 MHz, CDCl3) δ (ρm): 10.5; 10.8; 10.9; (CH3); 13.7 (OCH2CH2CH2CH3);
14.1; 14.2 (CH3); 18.8 (OCH 2 CH 2 CH 2 CH 3); 22.8; 23.2; 23.3; 23.7; 23.8; 23.9;
(CH2);
28.2 (C7H15CH2CH (CO) P); 28.7; 28.9; 29.4; 29.5; 29.8; 29.9; 30.4; 30.5; 30.7;
32.0 (CH2); 32.6 (d, J - 6.5 Hz, OCH 2 CH 2 CH 2 CH 3); 37.2; 37.3; 39.0; 39.2; 39.4 (CHCH2N); 41.9 ; 43.2 (d, J - 134.0 Hz, COCH (Oct) P); 49.9; 50.5; 50.7; 51.2; 52.0; 52.1;
52.7; 52.8 (CH2N); 65.6 (d, J - 6.5 Hz, OCH 2 CH 2); 169.3 (d, J - 5.0 Hz, C = O).
31 P NMR (160 MHz, CDCl3) δ (ppm): 26.8.
ESI +: [MH] - 530, [2M-H] - 1061 1.2 Synthesis of Other Useful Compounds According to the Invention The following compounds:
- 1- (N, N-di-2-ethylhexylcarbamoyl) isopropyl nonylphosphonate, noted DEHCNPiP, which corresponds to the general formula (I) above in which RI- - R2 - 2-ethyl-hexyl, R3-n-octyl and R4-isopropyl;

WO 2014/139869

18 PCT / EP2014 / 054418 ¨ 1- (N, N-di-2-ethylhexylcarbamoyl) -2-ethylhexylphosphonate isopropyl, denoted DEHCEHPiP, which corresponds to the general formula (1) above in which Fe = R2 = R3 =
2-ethylhexyl, and R4 = isopropyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) isobutyl nonylphosphonate, noted DEHCNPiB, which corresponds to the general formula (1) above in which R1 = R2 = 2-ethyl hexyl, R3 = n-octyl and R4 = isobutyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) -2-ethylhexylphosphonate isobutyl, denoted DEHCEHPiB, which corresponds to the general formula (1) above in which Fe = R2 = R3 =
2-ethylhexyl and R4 = isobutyl;
¨ 1- (N, N-di-n-octylcarbamoyl) isobutyl nonylphosphonate, noted DOCNPiB, which corresponds to the general formula (1) above in which R1 = R2 =
R3 =
n-octyl and R4 = isobutyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) -2-ethylhexylphosphonate n-butyl, denoted DEHCEHPB, which corresponds to the general formula (1) above in which R1 = R2 = R3 =
2-ethylhexyl and R4 = n-butyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) ethyl nonylphosphonate, noted DEHCNPE, which corresponds to the general formula (1) above in which R1 = R2 =
2-ethyl-hexyl, R3 = n-octyl and R4 = ethyl; and ¨ 1- (N, N-di-n-octylcarbamoyl) n-butyl nonylphosphonate, noted DOCNPB, which corresponds to the general formula (1) above in which Fe = R2 =
R3 = n-octyl and R4 = n-butyl;
are synthesized by implementing steps A, B, D and E shown in FIG.
figure 1 and using, for each of these steps, an operating protocol similar to the one described in point 1.1 above.
Are also synthesized:
¨ ethyl 1- (N, N-di-2-ethylhexylcarbamoyl) methylphosphonate, noted DEHCMPE, which corresponds to the general formula (1) above in which R1 = R2 =
2-ethyl-hexyl, R3 = H, R4 = ethyl; and WO 2014/139869

19 PCT / EP2014 / 054418 ¨ n-butyl 1- (N, N-di-2-ethylhexylcarbamoyl) methylphosphonate, noted DEHCMPB, which corresponds to the general formula (I) above in which RI- = R2 = 2-ethyl hexyl, R3 = H, R5 = n-butyl;
implementing steps A, B and C shown in FIG.
using, for steps A and B, an operating protocol similar to that described in point 1.1 above for these steps, and for step C, an operating procedure similar to that described in 1.1 above for step E.
EXAMPLE II PROPERTIES OF COMPOUNDS USEFUL ACCORDING TO THE INVENTION
11.1 - Selectivity of the extraction of uranium (VI) from an aqueous solution of sulfuric leaching by some of the compounds useful according to the invention :
The ability of the compounds useful according to the invention to extract selectively uranium (VI) of an aqueous solution of sulfuric acid was assessed by tests extraction that is made in tubes, using:
¨ as organic phases, phases comprising one of the compounds DEHCNPiP, DEHCEHPiP, DEHCNPiB, DEHCEHPiB, DEHCEHPB and DEHCNPB, As an extractant, at a concentration of 0.05 mol / L in TPH, the solubilization of these compounds in the TPH having been previously carried out without using modifier phase or heating; and ¨ as aqueous phases, aliquots of an aqueous solution from the leaching of a mixture of uranium ores from Canada and Niger by sulfuric acid. This mixture of ores makes it possible solution of leaching, of all the metallic elements likely to be present in sulfuric acid leaching solutions, namely: uranium (VI), arsenic, molybdenum, tungsten, iron, vanadium, titanium and zirconium.
The metallic element composition of this aqueous phase is presented in Table 1 below. Its total sulphate content (ions sulfate + ions hydrogen sulphate) is 0.40 mol / L while its concentration of H + ions is of 0.13 mol / L. Its redox potential, which is 680 mV / ENH, indicates that the iron WO 2014/139869

20 PCT / EP2014 / 054418 that it contains is predominantly at the oxidation state II while the vanadium is at the oxidation degree IV.
Table I
Elements Concentrations Metals (mg / L) 3,320 As 1 780 Mo 420 Fe 3,290 Ti 67 Zr 33 Each of the organic phases was brought into contact with a phase aqueous solution in a volume ratio organic phase / aqueous phase, denoted 0 / A, 1, and these phases were maintained for 30 minutes at room temperature (23-24 VS), in an incubator that prints a horizontal reciprocating motion to the tubes extraction. After that, the organic and aqueous phases were separated by gravity settling in less than 2 minutes.
The concentrations of the metallic elements were measured in the aqueous phases before and after extraction, by emission spectrometry Atomic plasma torch (ICP-AES). Their concentrations in the organic phases have been either measured either by X-ray fluorescence or by desextraction analytic to ammonium oxalate and then ammonium carbonate.
Table II below shows, for each compound tested, the coefficients of distribution of uranium, arsenic, molybdenum, iron, vanadium and titanium, respectively denoted Du, DAs, DM0, DFe, DV and Uri, having been obtained from of the concentrations thus measured.

WO 2014/139869

21 PCT / EP2014 / 054418 Also given in this table are the distribution coefficients having have been obtained for these same elements, under the same experimental conditions, But with an organic phase comprising Alamine 336, which is currently extractant the most used in uranium ore processing plants, at a concentration 0.1 mol / L in TPH supplemented with 2% isodecanol.
Table II
Distribution coefficients The Dmo DFe Dm DV DTi DEHCNPiP 30 0.02 0.015 ¨ 0.01 <10-3 0,015 DEHCEHPiP 7.6 0.06 0.015 ¨ 3.10-3 G 10-3 u, DEHCNPiB 14 0.015 0.015 ¨ 3.10-3 G 10-3 0.033 4 ..
vs bone 4 ..
o DEHCEHPiB 14 0.02 0.02 ¨ 3.10-3 G 10-3 CD
I-4-.
X
Read DEHCEHPB 0.04 0.015 ¨ 5.10-3 G 10-3 DEHCNPB 34 0.1 0.03 <0.01 ¨ 0.01 0.1 Alamine 336 278 15 3.10-3 0.04 <0.01 <i0 This table shows that the compounds which are useful according to the invention exhibit a ability to extract uranium (VI) from an aqueous solution of sulfuric acid and this, with selectivity greater than that of Alamine 336, particularly with respect to molybdenum. The steric hindrance provided by the ramification of the group alkyl phosphonate (R4) or the spacer between the amide function and the phosphonate (R3), causes a slight decrease in the distribution coefficient of uranium by report to that of the compound DEHCNPB, but still improves the selectivity of the compounds for uranium with respect to molybdenum and titanium, which are the main impurities potentially coextracted from an aqueous solution of sulfuric acid from the leaching Uranium ore with sulfuric acid. This gives a factor of separation from WO 2014/139869

22 PCT / EP2014 / 054418 the order of 1500 for U / Mo with the compound DEHCNPiP, whereas it is only 19 in the case of Alamine 336 at 0.1 mol / L.
The selectivity of the compounds which are useful according to the invention for uranium is very good vis-à-vis vanadium and titanium; for arsenic, it is better with Alamine 336. The selectivity of this family of extractants for uranium vis-à-vis the iron is less good than for Alamine 336 with which iron is not at all extract, but it remains nevertheless very high.
11.2 ¨ Isothermal extraction of uranium (VI) by a useful compound according to the invention:
In order to determine the isotherm of the extraction of uranium (VI) by a compound according to the invention, extraction tests were carried out in using:
¨ as organic phases, phases comprising the compound DEHCNPB
as an extractant at a concentration of 0.05 mol / L in TPH; and ¨ as aqueous phases, aqueous solutions of sulfuric acid 1.9 g / L of uranium (VI), 0.5 mol / L of total sulphates and an acidity 0.2 N, these last two parameters being representative of the concentrations in total sulphates and free acidity classically presented by solutions from the leaching of uranium ores by sulfuric acid;
and gradually lowering, from one test to another, the volume ratio 0 / A
from 2 to 0.067, so as to approach the uranium saturation of the phase organic.
These tests were carried out in stirred beaker, at a temperature of 23-24 C, with contact times between the organic phases and the aqueous phases of minutes.
After separation of the organic and aqueous phases, the concentrations of uranium and other metallic elements were measured:
¨ in the aqueous phases, by ICP-AES or, for the very weak uranium concentrations by plasma torch mass spectrometry (ICP-MS);
¨ in the organic phases, by X-ray fluorescence; and ¨ in aqueous solutions containing 0.5 mol / L of carbonate and in which uranium and other metallic elements summer organic extracts, by ICP-AES.

WO 2014/139869

23 PCT / EP2014 / 054418 The results of these tests are given in Table III below.
Table III
Volume ratios 0 / A
2 1 0.33 0.20 0.1 0.067 [U] aqueous phase I (mg / L) 0.018 0.83 536 998 1 427 1 818 [U] organic phase (Mg / L) I Of 53,000 2,299 7.1 4.1 2.6 2.4 They are also illustrated in Figure 2, in the form of a curve that shows the relationship to equilibrium between the concentration of uranium phase organic and the concentration of this same element in the aqueous phase. The slope of the tangent of the curve at any point gives the distribution coefficient of uranium in the absence of other metal elements.
Table III and Figure 2 show, on the one hand, that the coefficient of uranium distribution, noted Du, which is very high for the weak concentrations of uranium in the aqueous phase (almost vertical slope of the tangent of the curve), fall strongly as the concentration of uranium increases phase and, on the other hand, that a uranium saturation of the phase organic of the order of 4g of uranium / L.
11.3 ¨ Influence of acidity and total sulphate concentration of the solution aqueous sulfuric acid on the extraction of uranium (VI) by a compound useful according to the invention:
Solutions resulting from the leaching of uranium ores by acid sulfuric acid have a free acidity generally between 0.05 and 0.5 N and one total sulphate concentration (sulfate ions + hydrogen sulphate ions) between 0.1 and 2 mol / L, or even more, depending on the amount of sulfuric acid consumed for achieve this leaching and the amount of calcium leached since during this leaching it is WO 2014/139869

24 PCT / EP2014 / 054418 produces a partial reprecipitation of calcium sulfate dihydrate (or gypsum) whose Solubility is 2.4 g / L in water.
Knowing that, during the extraction of uranium (VI), this uranium is extracted under the form of UO22 + ions and that H + ions are released, it seemed interesting to know what is the influence of acidity and concentration of total sulphates of the solution water from which it is sought to extract uranium (VI) on this extraction.
To do this, extraction tests were performed in tubes agitated in using:
¨ as organic phases, phases comprising the compound DEHCNPB
as an extractant at a concentration of 0.05 mol / L in TPH; and ¨ as aqueous phases, solutions comprising 3.7 g / L of uranium (VI) and having total sulphate concentrations ranging from 0.3 to 1 mol / L
(by adding ammonium sulphate) and concentrations of H + ions equal to 0.2 N, 0.35 N and 0.5 N.
The results of these tests are illustrated in Figure 4 in which the curves A, B and C represent the evolution of the distribution coefficient of Uranium, noted Du, for a total sulphate concentration ranging from 0.3 to 1 mol / L and for a concentration of H + ions respectively 0.2 N (curve A), 0.35 N (curve B) and 0.5 N (curve C).
As this figure shows, there is a decrease in the coefficient of distribution of uranium when the concentration of total sulphates and acidity increase, but this decline is not very marked, which makes it possible to maintain good extraction efficiency while offering flexibility of use according to the type of ore treated uranium or, optionally, for a given uranium ore, according to evolution in time leaching conditions.
The distribution coefficient of uranium decreases when acidity increases, what was expected given the extraction mechanism that releases two protons by mole of uranium extracted. At constant acidity, the increase in ion concentration sulphate also has a negative effect on the extraction of uranium, but less Mark.

Claims (22)

25 1. Use of a compound of the following general formula (I):
in which :
R1 and R2, which may be identical or different, represent a hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 6 to 12 carbon atoms;
R3 represents:
¨ a hydrogen atom;
¨ a hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 1 to 12 carbon atoms and optionally one or more heteroatoms;
or ¨ a hydrocarbon group, saturated or unsaturated, monocyclic, comprising 3 at 8 carbon atoms and optionally one or more heteroatoms; while than R4 represents a hydrocarbon group, saturated or unsaturated, linear or branched, comprising from 2 to 8 carbon atoms, or a monocyclic aromatic group;
as an extractant, to extract uranium (VI) from an aqueous solution acid sulfuric acid in which it is present. 2. Use according to claim 1, wherein R1 and R2, which are identical or different, represent an alkyl group, linear or branched, comprising 6 to 12 carbon atoms. 3. Use according to claim 2, wherein R1 and R2 are identical between them and both represent a branched alkyl group comprising 8 at 10 carbon atoms. 4. Use according to claim 3, wherein R1 and R2 represent both are 2-ethylhexyl. Use according to any one of claims 1 to 4, wherein R3 represents a linear or branched alkyl group comprising from 1 to 12 atoms of carbon, or a monocyclic aromatic group. Use according to claim 5, wherein R3 represents a group alkyl, linear or branched, comprising from 6 to 10 carbon atoms, preference 2-ethylhexyl or n-octyl. Use according to any one of claims 1 to 5, wherein R4 represents a linear or branched alkyl group comprising from 2 to 8 atoms of carbon. Use according to claim 7, wherein R4 represents a group alkyl, linear or branched, comprising from 2 to 4 carbon atoms. Use according to claim 8, wherein R4 represents a group ethyl, isopropyl, n-butyl or isobutyl. The use according to any one of claims 1 to 9, wherein the compound is chosen from:
¨ n-butyl 1- (N, N-di-2-ethylhexylcarbamoyl) nonylphosphonate, which corresponds to the general formula (I) in which R1 and R2 each represent a group 2-ethylhexyl, R3 is n-octyl, while R4 is group n-butyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) isopropyl nonylphosphonate, which corresponds to the general formula (I) in which R1 and R2 each represent a group 2-ethylhexyl, R3 is n-octyl, while R4 is group isopropyl;
1- (N, N-di-2-ethylhexylcarbamoyl) -2-éthylhexylphosphonate isopropyl, which has the general formula (1) in which R1, R2 and R3 represent each a 2-ethylhexyl group while R4 is an isopropyl group;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) isobutyl nonylphosphonate, which corresponds to the general formula (1) in which R1 and R2 each represent a group 2-ethylhexyl, R3 is n-octyl, while R4 is group isobutyl;
1- (N, N-di-2-ethylhexylcarbamoyl) -2-éthylhexylphosphonate isobutyl, which has the general formula (1) in which R1, R2 and R3 represent each a 2-ethylhexyl group while R4 is an isobutyl group;
¨ 1- (N, N-di-n-octylcarbamoyl) isobutyl nonylphosphonate, which responds to the general formula (1) in which R1, R2 and R3 each represent a n-octyl group while R4 is isobutyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) -2-ethylhexylphosphonate n-butyl, which corresponds to the general formula (1) in which R1, R2 and R3 represent each a 2-ethylhexyl group while R4 is n-butyl;
¨ 1- (N, N-di-2-ethylhexylcarbamoyl) ethyl nonylphosphonate, which corresponds to the general formula (1) in which R1 and R2 each represent a group 2-ethylhexyl, R3 is n-octyl, while R4 is group ethyl; and ¨ n-butyl 1- (N, N-di-n-octylcarbamoyl) nonylphosphonate, which replies to the general formula (1) in which R1, R2 and R3 each represent a n-octyl group while R4 is n-butyl. 11. Use according to claim 10 which is 1- (N, N-di-2-ethyl) hexylcarbamoyl) n-butyl nonylphosphonate or 1- (N, N-di-2-éthylhexylcarbamoyI) -isopropyl nonylphosphonate. 12. Use according to any one of claims 1 to 11, in which compound is used to extract uranium (VI) from the solution aqueous acid sulfuric by liquid-liquid extraction. 13. Use according to any one of claims 1 to 12, in which compound is used in solution, at a concentration of 0.01 to 1 mol / L, in a organic diluent. 14. Use according to any one of claims 1 to 13, in which aqueous solution of sulfuric acid comes from leaching an ore uraniferous by sulfuric acid. 15. Use according to claim 14, wherein the aqueous solution of sulfuric acid comprises from 0.1 to 10 g / L of uranium (VI) and from 0.1 to 2 mol / L
ion sulfate, at an acidity of 0.01 to 0.5 mol / L. 16. Process for recovering uranium from an aqueous solution of sulfuric acid from the leaching of a uranium ore by the acid sulfuric, which method comprises:
a) extraction of the uranium, in oxidation state VI, from the aqueous solution sulfuric acid, by bringing this solution into contact with a phase organic comprising a compound as defined in any one of the claims 1 to 11, then separating said aqueous solution and said organic phase; and b) the extraction of uranium (VI) present in the organic phase obtained at the end of step a), by contacting this organic phase with a aqueous phase comprising a carbonate, and then separating said phase organic and of said aqueous phase. The method of claim 16, wherein the compound is used in solution, at a concentration of 0.01 to 1 mol / L, in an organic diluent. 18. The method of claim 16 or claim 17, wherein the aqueous sulfuric acid solution comprises from 0.1 to 10 g / L of uranium and 0.1 to 2 mol / L of sulfate ions, at an acidity of 0.01 to 0.5 mol / L. The method of any one of claims 16 to 18, wherein the aqueous phase comprising the carbonate comprises from 0.1 to 1 mol / L of carbonate. The method of any one of claims 16 to 19, wherein the volume ratio between the organic phase and the acid solution sulfuric acid used in step a) and / or the volume ratio between the organic phase and the phase aqueous including the carbonate used in step b) is (are) adjusted so that the sentence aqueous solution obtained at the end of stage b) has a concentration of uranium from 40 to 100 g / L. 21. The method of claim 20, wherein the volume ratio between the organic phase and the aqueous solution of sulfuric acid used in step a) is less than or equal to 1, while the volume ratio between the organic and aqueous phase comprising the carbonate used in step b) is greater than 1. 22. The method according to any one of claims 16 to 21, wherein step a) further comprises washing the organic phase after its separation from aqueous solution.