Method for Extracting Tantalum and Niobium from Acidic Aqueous Solutions

Abstract

The present invention relates to a method and apparatus for selectively extracting tantalum and optionally niobium by repeatedly performing extraction between a low-temperature single-phase region and a high-temperature two-phase region in a three-component prism far from the critical point, using a three-component mixture containing an acidic aqueous solution, an organic solvent immiscible with water, and a thermosensitive hydrotrope agent.

Description

Technical Field

[0001] The present invention relates to the field of extraction and purification of tantalum, and more particularly to a method for extracting and purifying tantalum and optionally niobium from acidic aqueous solutions.

Background Art

[0002] Strategic metals are present in many consumer goods such as hard disk drives for notebook computers, mobile phones, automobiles, batteries, and printed circuit boards. Like salt and pepper in food, these advanced technology materials are usually used in small amounts, but they are still essential components of these devices. To address the challenges of resource depletion and increasing demand, it seems essential to extract metals from low-grade ores, recover material flows from production waste, or process more complex objects at the end of their life through mining, recycling, or substitution.

[0003] As a result of numerous innovations growing dramatically in the above-described technical fields, the demand and price of rare earth elements (REE) have increased, and shortages in the supply routes have been recognized.

[0004] The selective extraction of different metals with similar physical and chemical properties is difficult. Tantalum (Ta) and niobium (Nb) are important transition metals and are widely used in various advanced technology industries. In particular, tantalum is an important element with high chemical inertness and high melting point used in alloys, wires, surgical instruments, and electrical components such as capacitors, while niobium is used in, among other things, steel, superalloys, superconducting magnets, medical devices, and jewelry.

[0005] The most important sources of Ta and Nb are tantalite (Fe,Mn)(Ta,Nb)2O6, columbite (Fe,Mn)(Ta,Nb)2O6, and microlite (Ca,Na)2(Ta,Nb)2(O,OH,F)7. Therefore, Ta and Nb almost always coexist geologically, and thus separation is difficult because their physical and chemical properties are very similar.

[0006] Liquid-liquid extraction is currently the most effective method for separating tantalum and niobium. The methods known in the art are mainly based on the use of a two-component mixture of an organic solvent and an aqueous solution containing 1-octanol or 2-octanol alone or in admixture with additional organic compounds such as octane or methyl isobutyl ketone (MIBK) (Zhourou Lu et al. “Solvent extraction technology for the separation and purification of indium and tantalum: a review”, Hydrometallurgy 107, 2011, pp. 1-12).

[0007] However, these methods are not entirely satisfactory because a significant increase in viscosity is observed in the solvent phase with respect to the amount of electrolyte solution that is generally efficient in practice in the “feed solution”, and the flash point of the most efficient known extractant (MIBK) is low, and furthermore, the miscibility of solvents such as cyclohexanone and the extractant is poor.

[0008] Therefore, there remains a need for a method for selectively and efficiently extracting tantalum and optionally niobium from an aqueous solution.

[0009] The method according to the invention, described below, makes it possible to meet this need.

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention relates to a method for selectively extracting at least tantalum in the form of an anionic salt from an acidic aqueous solution using a heat-sensitive ternary system.

[0011] The present invention is particularly applicable to the treatment of natural and / or industrial waste, and is obtained from a concentrate of a natural mineral rich in tantalum and optionally niobium, such as monazite, bastnasite, xenotime, pyrochlore, or columbotantalite, or a concentrate of a tantalum-rich mineral such as a concentrate obtained from the treatment of industrial and household waste containing tantalum, particularly electronic waste or "urban mines" consisting of tantalum products.

Means for Solving the Problems

[0012] The present invention first relates to a method for extracting tantalum in the form of a cationic salt from an acidic aqueous solution, and the method includes at least the following steps: i) At a first temperature T1, providing a three-component mixture including a) an acidic aqueous solution containing a mixture of metal elements including at least tantalum to be extracted, b) an organic solvent immiscible with water, and c) a thermosensitive hydrotrope agent Q1 containing a hydrophilic part and a hydrophobic part, where T1 is between 15 and 35 °C and lower than the critical temperature of the three-component mixture. ii) Heating the three-component mixture at a second temperature T2 at which the mixture exhibits a two-phase structure consisting of an aqueous phase and an organic phase rich in at least tantalum, where T2 is between 40 and 75 °C, higher than the critical temperature of the three-component mixture, and different from T1 by 15 to 50 °C. iii) Separating the organic phase from the aqueous phase in the two-phase structure obtained in step ii). iv) Extracting tantalum from the organic phase, where - The three-component mixture in step i) is in the pre-Ouzo zone of the phase boundary, and the pre-Ouzo zone is characterized as an ultra-flexible surfactant-free microemulsion containing dynamic aggregates in which about 20 to 300 molecules of aggregates are bonded to each other. - The hydrophilic part of the hydrotrope agent contains at least one ethoxy group. - The molar concentration of the acidic aqueous solution is at least 2M. The method includes these steps.

[0013] The present invention further relates to an installation for carrying out the method according to the invention for extracting at least tantalum in the form of an anionic salt from an acidic aqueous solution. More specifically, the installation comprises at least a mixing chamber and suitable cooling and heating means for said extraction. The installation also comprises the means necessary to ensure recirculation and separation means, as shown in Figure 2.

[0014] In a first aspect, the present invention relates to a method for extracting tantalum in the form of a cationic salt from an acidic aqueous solution, said method comprising at least the following steps: (i) providing a three-component mixture at a first temperature T1, comprising a) an acidic aqueous solution containing a mixture of metal elements containing at least tantalum to be extracted, b) an organic solvent immiscible with water, c) an amount Q1 of a thermosensitive hydrotrope agent containing a hydrophilic part and a hydrophobic part, wherein T1 is between 15 and 35 °C and lower than the critical temperature of said three-component mixture; (ii) heating said three-component mixture at a second temperature T2, at which said mixture exhibits a two-phase structure consisting of an aqueous phase and an organic phase carrying at least partially at least tantalum, wherein T2 is between 40 and 75 °C, higher than the critical temperature of said three-component mixture and different from T1 by 15 to 50 °C; (iii) separating said organic phase and said aqueous phase from the two-phase structure obtained in step (ii); (iv) extracting at least tantalum from said organic phase, - said three-component mixture of step (i) being in the pre-Winsor region of the phase boundary, said pre-Winsor region being characterized as a super-flexible surfactant-free microemulsion containing dynamic aggregates in which about 20 to 300 molecules are bound to each other, - said hydrophilic part of said hydrotrope agent containing at least one ethoxy group, - the molar concentration of said acidic aqueous solution being at least 2M and comprising the steps.

[0015] The three-component mixture in the "pre-wozo" region, also referred to as "surfactant-free microemulsion" or "super-soft microemulsion", is characterized by the following combination of properties: - It contains aggregates of more than 30 molecules locally covered by a part of the monolayer of hydrotropes as defined in Th.Zemb et al., Proceedings of the National academy of science of the USA, 2016, 113(16), 4260 - 4262, etc., - By static light scattering, the apparent average aggregate mass is more than 30 times the molecular weight of the solvent used, - The three-component mixture is far from its critical point, and for each component, the difference between the critical point and its mass % is at least 3%, preferably at least 5%, more preferably at least 8% in the case of tantalum and niobium.

[0016] According to the present invention, a "hydrotrope" is a compound soluble in both the aqueous phase and the organic phase. More precisely, a hydrotrope is a compound that solubilizes hydrophobic compounds in an aqueous solution. Hydrotropes typically consist of a hydrophilic part and a hydrophobic part (like surfactants), but the latter is usually too short to cause spontaneous self-assembly or micelle formation (J.Mehringer, Werner Kunz, 2021, Advances in Colloid and Interface Science 294, 102476). There are acidic, basic, or salt electrolyte hydrotropes and non-electrolyte hydrotropes. Its molar volume is 0.090 nm 3 superscript and less than 0.5 nm 3 subscript. According to the present invention, the "hydrotrope" is miscible with water and an organic solvent immiscible with water, and when present in an amount Q1 (also denoted as "minimum hydrotrope concentration (MHC)"), enables significant solubilization of at least tantalum in the form of anionic salts. The hydrotrope reduces the surface tension of water without forming micelles itself. This micellization is evidenced by the existence of a flat region of surface pressure with respect to the hydrotrope concentration.

[0017] According to the present invention, the term "thermosensitive" hydrotrope refers to a hydrotrope that can impart thermosensitivity to the demixing compositions of a three-component mixture of the hydrotrope, the organic solvent, and the hydrophobic substance.

[0018] According to the present invention, the term "dynamic aggregate" refers to aggregates in an aqueous solution that exhibit a critical aggregation concentration of 0.1 M or more at room temperature (determined by any standard technique such as surface tension) (S. Schottl and D. Horinek, Current opinion in Colloid & Interface Science, vol. 22 (2016) pp. 8-13).

[0019] The method according to the present invention presents the advantage of using a simple three-component system in which the properties of the organic solvent and the hydrotrope are combined in a single single-phase three-component mixture. In the method according to the present invention, steps (i) to (iii) may be repeated in a cyclic process including n reaction cycles by combining the fluxes of the aqueous phase and the organic phase in a countercurrent arrangement.

[0020] In the method according to the present invention, the diameter of the aggregates in the three-component mixture in step (i) is determined by any suitable method known to those skilled in the art, preferably by X-ray light scattering with a correlation length exceeding 2 nm.

[0021] According to the present invention, the "surfactant-free single-phase microemulsion structure" is intended to mean a single-phase three-component mixture having a microemulsion-like structure in which no surfactant is present in the mixture. The absence of a surfactant or detergent provides the advantage that the method according to the present invention is easier to implement and does not require the removal of the detergent.

[0022] The acidic aqueous solution containing a mixture of metal elements including at least tantalum to be extracted by the method of the present invention is, for example, an acid concentrate of ore or waste. The concentration of the tantalum in the acidic aqueous solution is preferably between 0.1 and 10 g / L.

[0023] According to the present invention, the acidic aqueous solution may be any solution containing a strong acid and having a molar concentration in the range of 2 to about 12 M. According to a preferred embodiment, the strong acid is sulfuric acid or nitric acid, and sulfuric acid is particularly preferred.

[0024] According to a specific embodiment of the present invention, the molar concentration of the acidic aqueous solution is at least 5 M. In that case, the method according to the present invention enables not only the extraction of tantalum but also the extraction of niobium. Therefore, according to this specific embodiment, the molar concentration of the acidic aqueous solution is at least 5 M, and the method according to the present invention is for selectively extracting tantalum and niobium from the acidic aqueous solution.

[0025] The amount of the aqueous solution in the three-component mixture in step (i) can be in the range of about 10 to 90% by weight (wt%), preferably about 15 to 80 wt%, based on the total weight of the three-component mixture.

[0026] According to the present invention, "immiscible with water" with respect to an organic solvent refers to an organic solvent that cannot be mixed with water and forms a heterogeneous mixture. More precisely, the definition includes solvents with a miscibility with water of less than 0.001 mole fraction, and the miscibility of water with the solvent is more than 0.1 mole fraction.

[0027] According to a specific embodiment of the present invention, the organic solvent is selected from aliphatic alcohols having a carbon chain containing at least 8 carbon atoms, gerb alcohol, ethyl acetate, aldehydes, ketones, phosphorus-based non-ionic liquids, amides, carbollides, carboranes, and phosphonates.

[0028] In certain preferred embodiments of the present invention, the organic solvent is selected from 1-octanol, 2-octanol, methyl isobutyl ketone (MIBK), cyclohexanone, and tributyl phosphate (TBP). Among these organic solvents, 1-octanol and 2-octanol are particularly preferred.

[0029] The amount of the organic solvent in the three-component mixture of step (i) can be in the range of about 5 to 70% by weight (wt%), preferably about 5 to 50 wt%, based on the total weight of the three-component mixture.

[0030] According to the present invention, the amount Q1 of the hydrotropic agent is typically more than 10% by weight of the weight of the three-component mixture, preferably 10 to 55% by weight of the total weight of the three-component mixture, more preferably 20 to 50% by weight of the weight of the three-component mixture.

[0031] Examples of the hydrotropic agent are propylene glycol alkyl ethers in which the alkyl is selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and pentyl, such as 1-propoxy-2-propanol (PnP) and dipropylene glycol n-propyl ether (dPnP).

[0032] Among these hydrotropic agents, 1-propoxy-2-propanol is particularly preferred.

[0033] In a particular embodiment of the method according to the present invention, to prepare the three-component mixture of step (i), step (i) initially includes mixing the organic solvent and the hydrotropic agent, and then includes the addition of the acidic aqueous solution.

[0034] According to the present invention, both T1 and T2 are different from the critical temperature of the three-component mixture, and the respective differences between T1 or T2 and the critical temperature of the three-component mixture are at least 3°C, preferably at least 5°C, more preferably at least 10°C.

[0035] The critical temperature of a given three-component mixture is readily determined by established methods such as those described in Alberto Arce, Alberto Arce, Jr., and Oscar Rodriguez, J. Chem. Eng. Data 2022, 67, 286-296.

[0036] According to a preferred embodiment of the present invention, T1 ranges from about 15 to 35 °C, more preferably from about 20 to 30 °C.

[0037] According to a preferred embodiment of the present invention, T2 ranges from about 45 to 70 °C, more preferably from about 50 to 65 °C.

[0038] The heating of the three-component mixture from temperature T1 provided in step (i) to temperature T2 in step (ii) can be carried out by any means or apparatus suitable for heating said mixture known to those skilled in the art. Examples include microwave or Bain Marie.

[0039] In step (iii), the organic phase can be separated from the aqueous phase by any suitable means such as, for example, draining, pipetting, centrifugation, etc.

[0040] In step (ii), temperature T2 is maintained for a time sufficient for phase separation to occur and for at least the solvent extraction of tantalum from the three-component mixture into the organic phase, typically 1 to 20 minutes. If necessary for intensification, the treatment can be accelerated 100-fold using a centrifugal extractor at low acceleration (<3000 g).

[0041] According to the present invention, both T1 and T2 are different from the critical temperature of the three-component mixture, and the difference between T1 or T2 and the critical temperature of the three-component mixture is at least 3 °C, preferably at least 5 °C, more preferably at least 10 °C. In a particular embodiment of the present invention, during step (ii), the three-component mixture can be centrifuged. This centrifugation carried out during step (ii) is intended to facilitate and / or accelerate at least the extraction of tantalum according to the method of the present invention.

[0042] According to a specific preferred embodiment of the present invention, steps (i) to (iii) are repeated at least once, more preferably 2 to 20 times, and even more preferably 3 to 6 times, before performing step (iv) and after returning the three-component mixture to temperature T1.

[0043] In that case, according to a first implementation mode of this specific embodiment, the method includes at least the following sub-steps after step (iii) and before each repetition of steps (i) to (iii): (1a) Cooling the aqueous phase recovered in step (iii) to temperature T1; (2a) Mixing the aqueous phase with the organic solvent and the hydrotrope to obtain the three-component mixture; and (3a) Adjusting the amount of the hydrotrope in the three-component mixture to the amount Q1.

[0044] This first implementation mode is preferably carried out when one repetition of steps (i) to (iii) is not sufficient to extract all the tantalum initially present in the first acidic aqueous solution, or not sufficient to further extract niobium from the first acidic aqueous solution. In the latter case, the molar concentration of the acidic aqueous solution is then adjusted to at least 5 M to extract niobium.

[0045] According to a second implementation mode of this specific embodiment, the method includes at least the following sub-steps after step (iii) and before each repetition of steps (i) to (iii): (1b) Cooling the organic phase recovered in step (iii) to temperature T1; (2b) Mixing the organic phase with a new acidic aqueous solution containing a mixture of metal elements including at least the tantalum to be extracted and the hydrotrope to obtain the three-component mixture; and (3b) Adjusting the amount of the hydrotrope in the three-component mixture to the amount Q1.

[0046] This second implementation mode is preferably carried out to obtain an organic phase containing at least tantalum at a high concentration.

[0047] In both the first and second implementation modes of this specific embodiment, in order to maintain the efficiency of the distribution coefficient during step (ii), the amount of the hydrotropic agent in the three-component mixture needs to be adjusted to the amount Q1 in step (3a) or (3b).

[0048] In both the first and second implementation modes of this specific embodiment, the cooling steps (1a) and (1b) from temperature T2 to temperature T1 can be carried out by any cooling device such as an ice bath or a refrigeration device.

[0049] In step (iv), the extraction of tantalum from the organic phase may be carried out by washing the organic phase with an acidic aqueous solution. As an example, when the organic solvent of the organic phase is octanol, the organic phase can be washed with a 0.1 - 0.2 M sulfuric acid aqueous solution to transfer tantalum from the organic phase to the sulfuric acid aqueous solution. As another example, when the organic phase contains both tantalum and niobium, the organic phase is first washed with a 3.5 - 4.0 M first sulfuric acid aqueous solution to transfer niobium from the organic phase to the first sulfuric acid aqueous solution, and then the organic phase is washed with a 0.1 - 0.2 M second sulfuric acid aqueous solution to transfer tantalum from the organic phase to the second sulfuric acid aqueous solution.

[0050] In a second aspect, the present invention relates to a facility for extracting at least tantalum in the form of an anionic salt according to the method defined according to the first aspect of the present invention.

[0051] More specifically, the present invention relates to a facility for implementing the method according to the present invention, and the facility comprises at least the following: - a) An acidic aqueous solution containing a mixture of metal elements containing at least tantalum to be extracted, b) An organic solvent immiscible with water, c) A mixing chamber for preparing a three-component mixture containing a hydrotropic agent of amount Q1, which contains a hydrophilic part and a hydrophobic part, and the hydrophilic part contains at least one ethoxy group. - A heating device for heating the three-component mixture, - A cooling device, - Means for transporting the acidic aqueous solution, the organic solvent, the thermosensitive hydrotrope, and the mixture, and - Means for controlling at least the flow rate and temperature of the solution and the mixture.

[0052] Further features and advantages of the present invention will become apparent from the following detailed description of the embodiments and the accompanying drawings.

Brief Description of the Drawings

[0053]

Figure 1A

Figure 1B

Figure 2

Figure 3

DETAILED DESCRIPTION OF THE INVENTION

EXAMPLE

[0054] Separation of Tantalum and Niobium In this example, the selective extraction of tantalum and niobium by the method of the present invention will be described.

[0055] Prepare a three-component mixture containing the following: · An acidic aqueous phase of 4M sulfuric acid containing niobium and tantalum · 1-propoxy-2-propanol (PnP) as a temperature-sensitive hydrotropic agent to ensure miscibility between the aqueous phase and the organic solvent · 2-octanol as an organic solvent immiscible with water.

[0056] The phase diagrams and separation factors at 25°C and 60°C for this system are shown in FIGS. 1A and 1B, respectively.

[0057] As can be seen from this figure, the distribution coefficient (kD) and the Ta / Nb separation factor (lnS) show two maximum values near the compositions listed in Table 1 below.

Table 1

[0058] In the first step, an aqueous phase, PnP, and 2-octanol were mixed as follows: PnP and 2-octanol were mixed at a ratio of 0.82 and 0.18 with an allowable error of ±0.02, and then an aqueous solution was added so that the mass fraction of PnP / 2-octanol / aqueous solution was 0.4 / 0.1 / 0.5, and the variation of each component was set to 0.03 (a point between two straight lines indicating 25 °C and 60 °C).

[0059] When the three components of this composition were mixed at a low temperature T1 of 25 °C, a microemulsion with a uniform nanostructure was formed, showing specific advantages such as a large contact surface between the aqueous phase and the organic phase, low viscosity, and rapid attainment of thermodynamic equilibrium. At this temperature, the ions were distributed between the existing aqueous phase and the pseudo-organic phase according to the partition coefficient.

[0060] In the second step, the temperature was raised to 60 °C (T2). Due to the temperature sensitivity of the hydrotrope, the phase boundary of the three-component system changed as shown in Fig. 1A. As a result, it separated into a water-rich phase and an organic-rich phase. As shown in Fig. 1, since the partition coefficient was more than 50, which was advantageous for the solvent phase, separation from iron and purification by combining elements in a cascade became possible. This step can be accelerated using a centrifuge. The volume ratio of these two phases depends on the corresponding line of the phase diagram at 60 °C. Tantalum mainly migrates to the organic-rich phase, while niobium mainly remains in the aqueous phase. The separation coefficient is high and depends on the initial composition of the phase diagram (see Fig. 1B).

[0061] As shown in Fig. 2, by combining the fluxes of the aqueous phase and the organic phase in a countercurrent arrangement, the number of cycle steps can be increased, and as a result, the separation between the two metals can be increased. In each step, the aqueous phase and the organic phase are mixed at an appropriate volume ratio at room temperature to form a uniform phase. Then, the temperature is raised again, the two obtained phases are separated, and transferred to the next cycle chamber. The cycle including steps (ii) and (iii) can be performed 3 to 20 times, preferably 6 to 10 times.

Claims

1. A method for extracting tantalum from an acidic aqueous solution in the form of a cation salt, comprising at least the following steps: (i) A step of providing a three-component mixture at a first temperature T1, comprising: a) an acidic aqueous solution containing a mixture of metal elements including at least tantalum to be extracted; b) an organic solvent immiscible with water; and c) a thermosensitive hydrotrope in amount Q1, wherein T1 is between 15 and 35°C and lower than the critical temperature of the three-component mixture. (ii) A step of heating the three-component mixture at a second temperature T2 such that the mixture exhibits a two-phase structure consisting of an aqueous phase and an organic phase supporting at least partially tantalum, wherein T2 is between 40 and 75°C, is higher than the critical temperature of the three-component mixture, and is 15 to 50°C different from T1. (iii) A step of separating the organic phase and the aqueous phase from the two-phase structure obtained in step (iii), (iv) A step of extracting at least tantalum from the organic phase, - The three-component mixture of step (i) is in the pre-ouzo region of the phase boundary, and the pre-ouzo region is characterized as a superflexible surfactant-free microemulsion containing dynamic aggregates of about 20 to 300 molecules bonded to each other. - The hydrophilic portion of the hydrotrope agent contains at least one ethoxy group, - The molar concentration of the acidic aqueous solution is at least 2 M. process A method that includes this.

2. The method according to claim 1, wherein the concentration of tantalum in the acidic aqueous solution is between 0.1 and 10 g / L.

3. The method according to claim 1, wherein the molar concentration of the acidic aqueous solution is in the range of 2 to 12 M.

4. The method according to claim 1, wherein the acidic aqueous solution contains a strong acid selected from sulfuric acid and nitric acid.

5. The method according to claim 1, wherein the molar concentration of the acidic aqueous solution is at least 5 M, and the method is for selectively extracting tantalum and niobium from the acidic aqueous solution.

6. The method according to claim 1, wherein the amount of the acidic aqueous solution in the three-component mixture in step (i) is in the range of 10 to 90% by weight of the total weight of the three-component mixture.

7. The method according to claim 1, wherein the organic solvent is selected from 1-octanol, 2-octanol, methyl isobutyl ketone, cyclohexanone, and tributyl phosphate.

8. The method according to claim 1, wherein the amount of the organic solvent in the three-component mixture in step (i) is in the range of 5 to 70% by weight of the total weight of the three-component mixture.

9. The method according to claim 1, wherein the hydrotrope is 1-propoxy-2-propanol or dipropylene glycol n-propyl ether.

10. The method according to claim 1, wherein the amount Q1 of the hydrotrope agent in the three-component mixture of step (i) is in the range of 10 to 55% by weight of the total weight of the three-component mixture.

11. The method according to claim 1, wherein T1 is in the range of 20 to 30°C.

12. The method according to claim 1, wherein T2 is in the range of 45 to 70°C.

13. The method according to claim 1, wherein steps (i) to (iii) are repeated at least once before performing step (iv) and after the three-component mixture has been returned to temperature T1.

14. The method may include at least the following sub-steps after step (iii) and before each iteration of steps (i) through (iii): (1a) A step of cooling the aqueous phase recovered in step (iii) to a temperature T1, (2a) A step of mixing the aqueous phase with the organic solvent and the hydrotrope agent to obtain the three-component mixture, (3a) A step of adjusting the amount of the hydrotrope agent in the three-component mixture to the amount Q1. The method according to claim 13, including the method described in claim 13.

15. The method may include at least the following sub-steps after step (iii) and before each iteration of steps (i) through (iii): (1b) A step of cooling the organic phase recovered in step (iii) to a temperature T1, (2b) A step of mixing the organic phase with a new acidic aqueous solution containing a mixture of metal elements including at least the tantalum to be extracted and the hydrotrope agent to obtain the three-component mixture, and (3b) A step of adjusting the amount of the hydrotrope agent in the three-component mixture to the amount Q1. The method according to claim 13, including the method described in claim 13.

16. An apparatus for carrying out the method described in any one of claims 1 to 15, wherein at least: - A mixing chamber for preparing a three-component mixture comprising: a) an acidic aqueous solution containing a mixture of metal elements including at least tantalum to be extracted; b) an organic solvent immiscible with water; and c) a hydrotrope agent in amount Q1 comprising a hydrophilic portion and a hydrophobic portion, wherein the hydrophilic portion contains at least one ethoxy group. - A heating device for heating the three-component mixture, - cooling equipment, - Means for transporting the acidic aqueous solution, the organic solvent, the heat-sensitive hydrotrope agent, and the mixture, and - Means for controlling at least the flow rate and temperature of the solution and mixture. Equipment equipped with the following features.

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