WO2024174036A1 - Solvent extraction method and system - Google Patents

Abstract

Disclosed is a method for separation of one or more target species from a first solvent phase. The method involves passing the first solvent phase containing the one or more target species, and a first portion of a second solvent phase, through a first set of one or more columns containing discontinuous packing medium. The first solvent phase and second solvent phase are immiscible with one another, and flow of the first solvent phase and the second solvent phase is co-current. Permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase. Also disclosed is a system for carrying out the method disclosed herein.

Description

SOLVENT EXTRACTION METHOD AND SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to US provisional applications 63/448060 filed on Feb 24, 2023, having the title SOLVENT EXTRACTION METHOD AND SYSTEM. The content of the above patent application is hereby expressly incorporated herein by reference into the detailed description thereof.

FIELD

[0002] The specification relates to a method for solvent extraction of one or more target species in a first solvent phase into a second solvent phase. In addition, the specification relates to a system for carrying out the method for solvent extraction.

BACKGROUND

[0003] Solvent extraction

[0004] Solvent extraction ("SX") (100) is a maturing chemical process, and involves a liquid-liquid separation process, used for the extraction of one or more ions in an initial solution, by contacting it with a second solution. By repeating this process many times, it is possible to separate even similar elements from one another.

[0005] The Feed Solution (102) is the initial aqueous solution subjected to the SX process. In the case of SX for metals extraction, this can be produced by dissolving a solid (usually, though not always, a chemical concentrate that results from upstream processes) that contains one or more target metals, typically into an acidic solution such as hydrochloric acid ("HCI"). The Feed Solution (102) can also be a pre-existing solution, such as a lithium ("Li") brine that already contains the target metal(s).

[0006] In conventional SX processes for the extraction of metals, the Feed Solution (102) is contacted with an organic solution (the "Organic" or "Organic Phase") that typically consists of an aliphatic diluent (such as kerosene) into which one or more specific extractants have been dissolved (the "Extractants"). The Extractants are typically complex organic compounds that are chosen for their ability to selectively bond with the target metal(s) in solution. There are numerous Extractants available commercially for SX.

[0007] An SX operation (100) can be described as a chemical circuit, consisting of a number of unit operations. Figure 1 shows a block diagram for a typical SX circuit (100) used for the separation of metals. The five typical unit operations are as follows:

[0008] Extract (104): transfer of the target metal ions from the Feed Solution (102) to the Organic Phase (106), leaving behind a depleted Raffinate (108);

[0009] Scrub (110): removal of impurities (i.e. non-target metal ions) from the Organic Phase, using an aqueous solution (such as HCI), which is referred to as the Scrub Solution (112) and is typically recycled back to Extract (104);

[0010] Strip (114): transfer of the target metal ions from the Organic Phase into fresh aqueous solution (such as HCI), to produce the Rich Strip (116) while the Organic Phase is re-generated;

[0011] Wash (118): washing or cleaning of the Organic Phase to remove any residual target and non-target ions, with the resulting Wash Solution (120) typically being recycled back to Strip (this step can also help bring the pH up, thereby lowering the amount of sodium hydroxide (NaOH) required in the following pre-neutralization step); and [0012] Pre-Neutralization (122): also referred to as pre-loading or saponification, an optional unit operation used with certain Feed Solutions, where metals such as sodium ("Na") are added to the Organic Phase through the addition of a solution such as sodium hydroxide ("NaOH"), for subsequent exchange with target metal ions in Extract (104).

[0013] The Organic Phase (106) is systematically transferred from each unit operation to the next, and is recycled back to Extract (104), once the later unit operations have been completed.

[0014] The Raffinate (108) and Rich Strip (116) produced from an SX circuit (100) may then be used, as appropriate, as the Feed Solutions for additional separations in subsequent SX circuits, and so on, until final Raffinate and Rich Strip solutions are produced, predominantly containing the desired target metal ions only, at acceptable purity levels (typically 99-99.9%), which will subsequently be processed using standard unit operations such as precipitation and calcining, to produce solid compounds that contain the separated metal.

[0015] The aqueous solution present in any given SX unit (100) operation is also referred to as the Aqueous or the Aqueous Phase. In Extract (104) and PreNeutralization (122), the goal is to move metal ions from the Aqueous into the Organic. In the Scrub (110), Strip (114) and Wash (118) unit operations, the goal is to move metal ions from the Organic into the Aqueous.

[0016] The contacting process used to encourage this movement or diffusion of metal ions between the Aqueous and Organic Phases, is traditionally accomplished through actively mixing the two solutions together in a tank (the "Mixer"), and then allowing them to coalesce or settle out in a second tank (the "Settler"). The mixing station uses a rotary stirrer to force contact between the aqueous phase that can contain the target element (along with other elements) and the lighter organic phase. The two phases are nominally horizontal, and the mixer attempts to increase the surface area of the two solutions in contact with one another. This mixing action can create significant microbeads of the two phases which are then sent to a settler to separate as best they can. Since the two solutions are immiscible, they will separate, with the Organic floating on top of the Aqueous (similar to how oil and water naturally separate after being mixed together).

[0017] The equipment traditionally used in this process is referred to as a Mixer-Settler Contactor. Each unit operation will utilize one or more Mixer-Settler Contactors, to achieve the objectives of the particular unit operation. Each Mixer- Settler Contactor is referred to as a Stage (199) within a given unit operation.

[0018] Some Mixer-Settler Contactors have the option of bleeding fractions of the respective output Aqueous and Organic Phases back into the respective input streams via recycle valves, as a means of increasing the relative concentration of ions that have been transferred from one Phase to the other, during mixing.

[0019] In addition to the above, there are several column-based approaches to solvent extraction that do not use a mixer-settler contactor as described above. They generally fall in two broad categories.

[0020] The first is a non-agitated column extractor, which has no moving internal parts. Examples include spray columns, packed columns, and sieve-tray columns. In each case, the phases contact each other in a counter-current manner. The second is an agitated column extractor, which are similar to non-agitated extractors, but which have mechanical assistance to agitate the phases as they pass through the column. Examples include:

• Pulsed columns, where a pump is used to create pressure waves (typically with air) in the phases as they move through the column. Baffles may be included along the length of the column to encourage mixing and dispersion of one phase into another. An example is the Tenova Pulsed Column.

• Perforated-plate columns, also known as sieve-tray columns, where the dispersed phase coalesces at plates inserted along the length of the column, before moving through perforations in them. Sometimes they are combined with the pulsing mechanism described previously; and • Rotary-agitated columns, which contain internal mechanisms that rotate, agitating the phases as they flow through the column with rotating disks. They typically have different mixing and settling zones within the column. The mixing zones typically have turbine impellers that operate between baffles. Examples include Scheibel and Oldshue-Rushton columns.

[0021] With each type of agitated column, the Aqueous enters the column at the top, and the Organic enters from the bottom, resulting in counter-current flow within the column.

[0022] Chemical Similarity

[0023] For a given Extractant, each metal has a specific profile for the effectiveness of bonding with the Extractant, or release from it, usually as pH or acidity levels change. The perfect Extractant would be one which, for a specific operating condition, the Extractant would bond with (or release from) the target metal only, while not interacting with the other metal ions present.

[0024] In practice, because metals from the same groups within the Periodic Table have similar chemical properties, these profiles will often overlap, which reduces selectivity.

[0025] The result is that for each SX unit operation (100), multiple Stages (199) are often required in order to ultimately achieve acceptable purity levels for the Raffinate (108) and Rich Strip (116) solutions (the two key work products from any SX circuit). One of the most extreme examples of this is for the separation of rare-earth elements ("REEs") from each other, where dozens of Stages (199) may be required in each unit operation, within a given conventional SX circuit (100).

[0026] The Distribution Coefficient K is a measure of how well a metal can be extracted into the Organic from the Aqueous. K affects the yield of the process, and depends on the Extractant used, the rate of diffusion, contact time and other process parameters. For a given metal, A:

[0027] KA - Quantity of A in Organic

Quantity of A in Aqueous [0028] The Separation Factor S is a measure of the selectivity of extraction. S influences the purity of the resulting solutions - essentially what gets extracted and what does not. For given metals, A and B:

[0029] SAB = K

KB

[0030] Lower Separation Factors lead to more Stages (199) being required for effective separation in a given unit operation - the same process has to be repeated within a given unit operation, using additional Stages (199), to achieve desired yields and purities. The specific number and distribution of Stages (199) within the various unit operations is known as the Staging.

[0031] Figure 2 shows a representative block diagram of the Extract Staging (200) for a conventional SX circuit (100), used for separating REEs with Mixer- Settler Contactors.

[0032] The two solutions in any given unit operation flow counter-current to each other. In the example in Figure 2 there are 10 Stages (199) (EXI - EX10); the Organic flows into Stage EXI (201); after completion of mixing and settling it then flows out of EXI (201) and into EX2 (202), from there to EX3 (203) and so on; while the Feed and Scrub Solutions flow in the other direction - from EX10 (210), to EX9 (209), to EX8 (208) and so on.

[0033] There is still a need in the art for improving the solvent extraction process, or providing an alternative solvent extraction process. In particular, there is a need in the art for an alternative method for solvent extraction that can avoid creation of significant microbeads of the two phases when mixed. In addition, there is a need in the art for a process that can provide a high surface area contact (and mass transfer) between the phases without the need for vigorous mixing. Further, there is a need in the art for a process that can improve the rate of transport of desired elements between two phases (aqueous and organic). Moreover, there is a need in the art for a process that can address one or more of the following: reduce the footprint of operation, reduce the amount of inventory in processing, such as, the volume of organic solvent in the process, allow for a more rapid restart of a processing facility, reduce energy consumption in the process, improve separation of desired elements, and reduce volatilization of organics into the atmosphere.

SUMMARY OF THE SPECIFICATION

[0034] In one aspect, the specification relates to a method for separation of one or more target species from a first solvent phase, the method containing the steps of:

[0035] passing the first solvent phase containing the one or more target species, and a first portion of a second solvent phase, through a first set of one or more columns containing discontinuous packing medium, wherein the first solvent phase and second solvent phase are immiscible with one another, and flow of the first solvent phase and the second solvent phase is co-current; and

[0036] permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase.

[0037] In another aspect, the specification relates to a system for extraction of one or more target species from a first solvent phase to a second solvent phase, the system containing :

[0038] a first set of one or more columns containing discontinuous packing medium,

[0039] wherein the system is configured for co-current flow of the first solvent phase and the second solvent phase, and permits contact of the first solvent phase with the second solvent phase as the solvents flow through the discontinuous packing medium.

[0040] In a third aspect, the specification relates to a process for purification of one or more target species, the process comprising:

[0041] an extraction step in fluid communication with a scrubbing step, and a stripping step in fluid communication with the scrubbing step, [0042] wherein at least one of the extraction step, scrubbing step and the stripping step comprises the method as disclosed herein.

[0043] In a fourth aspect, the specification relates to a system for purification of one or more target species, the system comprising:

[0044] an extraction stage in fluid communication with a scrubbing stage, and a stripping stage in fluid communication with the scrubbing stage,

[0045] wherein at least one of the extraction stage, scrubbing stage and the stripping stage comprises the system as disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which:

[0047] Figure 1 is a block diagram showing typical unit operations and fluid flows in a conventional SX circuit (100);

[0048] Figure 2 is a block diagram showing Staging (200) for the Extract unit operation in a representative conventional SX circuit (100) for REE separation using Mixer-Settler Contactors;

[0049] Figure 3 is a schematic showing a RapidSX™ Contactor (1) according to an embodiment of the specification, showing an in-flow manifold (single port or multi-port depending on the column diameter) for receiving the input solutions and subsequently distributing them, a single column filled with discontinuous media that received the solutions, and a settler;

[0050] Figure 4 is a schematic showing A) a side view and B) a front view of a RapidSX™ Contactor according to another embodiment disclosed in the specification, showing an in-flow manifold for receiving the input solutions and subsequently distributing them, four columns filled with discontinuous media that received the solutions, and a shared settler; [0051] Figure 5 is a schematic showing a RapidSX™ Contactor according to another embodiment disclosed in the specification, showing an in-flow manifold for receiving the input solutions and subsequently distributing them, a single column filled with discontinuous media that received the solutions, a settler, and recycle valves to allow bleeding of quantities of the respective output solutions back into the respective input solutions coming into top of the stage;

[0052] Figure 6 is a schematic showing A) a side view and B) a front view of a RapidSX™ Contactor according to another embodiment disclosed in the specification, showing an in-flow manifold for receiving the input solutions and subsequently distributing them, four columns filled with discontinuous media that received the solutions, a shared settler, and recycle valves to allow bleeding of quantities of the respective output solutions back into the respective input solutions coming into the top of the stage;

[0053] Figure 7 is a block diagram showing Staging for the Extract, Scrub, Strip, Wash and Pre-Neutralization unit operations in an SX circuit for REE separating using RapidSX™ Contactors, as described in Example 1 below.

[0054] In each of Figures 2-7, solid line arrows indicate flow of Aqueous Phase and dotted line arrows indicate flow of Organic Phase.

[0055] Similar reference numerals may have been used in different figures to denote similar components.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0056] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In addition, although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present invention, the typical materials and methods are described herein. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. Any patent applications, patents, and publications are referred to herein are to assist in understanding the aspects described. Each of these references are incorporated herein by reference in their entirety.

[0057] When introducing elements disclosed herein, the articles "a", "an", "the", and "said" are intended to mean that there may be one or more of the elements.

[0058] The term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, "including", "having" and their derivatives. It will be understood that any embodiments described as "comprising" certain components may also "consist of" or "consist essentially of," these components, wherein "consisting of" has a closed- ended or restrictive meaning and "consisting essentially of" means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effects described herein.

[0059] It will be understood that any component defined herein as being included may be explicitly excluded from the claimed invention by way of proviso or negative limitation, such as any specific compounds or method steps, whether implicitly or explicitly defined herein.

[0060] In addition, all ranges given herein include the end of the ranges and also any intermediate range points, whether explicitly stated or not.

[0061] Finally, terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies. [0062] The abbreviation, "e.g." is derived from the Latin exempli gratia, and is used herein to indicate a non-limiting example. Thus, the abbreviation "e.g." is synonymous with the term "for example." The word "or" is intended to include "and" unless the context clearly indicates otherwise.

[0063] The phrase "at least one of" is understood to be one or more. The phrase "at least one of...and..." is understood to mean at least one of the elements listed or a combination thereof, if not explicitly listed. For example, "at least one of A, B, and C" is understood to mean A alone or B alone or C alone or a combination of A and B or a combination of A and C or a combination of B and C or a combination of A, B, and C.

[0064] As noted above, in one aspect, the specification relates to a method for separation of one or more target species from a first solvent phase, the method containing the steps of: passing the first solvent phase containing the one or more target species, and a first portion of a second solvent phase, through a first set of one or more columns containing discontinuous packing medium, wherein the first solvent phase and second solvent phase are immiscible with one another, and flow of the first solvent phase and the second solvent phase is co-current; and permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase.

[0065] In another aspect, the specification relates to a system for extraction of one or more target species from a first solvent phase to a second solvent phase, the system containing : a first set of one or more columns containing discontinuous packing medium, wherein the system is configured for co-current flow of the first solvent phase and the second solvent phase, and permits contact of the first solvent phase with the second solvent phase as the solvents flow through the discontinuous packing medium.

[0066] In a third aspect, the specification relates to a process for purification of one or more target species, the process comprising: an extraction step in fluid communication with a scrubbing step, and a stripping step in fluid communication with the scrubbing step, wherein at least one of the extraction step, scrubbing step and the stripping step comprises the method as disclosed herein.

[0067] In a fourth aspect, the specification relates to a system for purification of one or more target species, the system comprising: an extraction stage in fluid communication with a scrubbing stage, and a stripping stage in fluid communication with the scrubbing stage, wherein at least one of the extraction stage, scrubbing stage and the stripping stage comprises the system as disclosed herein.

[0068] The term "separation" as used herein is not particularly limited and should be understood by a person of skill in the art. In the context of the present specification, separation can involve separation of one or more target species from other species present in a medium. For example, separation can involve removal of the target species, which can be, for example and without limitation, one or more metals of interest, from a first phase into a second phase, to help separate the target species from other impurities present in the first phase. In this way, carrying out the separation can lead to improvement in the purity of one or more target species by removal of the other species. In accordance with the specification, the separation is carried out using a liquid-liquid extraction.

[0069] The term "target species" is not particularly limited and should be understood by a person of skill in the art. The term can include any compound, element, complex or ion which it is desired to separate from the solution in which it occurs. The specification has particular utility for the separation of metals from aqueous solutions but could conceivably be applied to any situation where solvent extraction (SX) is presently utilized as a separation method.

[0070] The term "solvent" as used herein is not particularly limited and should be understood by a person of skill in the art. A solvent is a substance that contains or dissolves a solute. In accordance with the specification, two different solvents can be used for carrying out the separation, which include a first solvent phase and a second solvent phase. The two solvent phases selected are immiscible with one another, as disclosed herein, and are not particularly limited and can be determined by a person of skill in the art. In addition, the two solvents can be selected based on design and application requirements. Further, the terms "first solvent phase" and "second solvent phase" are not particularly limited and should be understood by a person of skill in the art. The first solvent phase and second solvent phase can vary depending upon the unit operation being carried out. In one embodiment, for example and without limitation, if the unit operation is a stage of an extraction step, the first solvent phase can be the aqueous phase that contains the one or more target species, while the second solvent phase can be the organic phase. In a second embodiment, for example and without limitation, if the unit operation is a stage of strip step, the first solvent phase can be the organic phase that contains the one or more target species, while the second solvent phase can be the aqueous phase. It should be noted and understood by a person of skill in the art that although the present specification describes the invention predominantly by referring to the extraction step, the invention can be carried in other unit operations as well.

[0071] The step of passing the first solvent phase containing the one or more target species, and a first portion of a second solvent phase, through a first set of one or more columns (4) is not particularly limited, and should be understood by a person of skill in the art. The step can involve fluid flow of the first solvent phase, and a first portion of a second solvent phase, through the one or more columns (4). Such fluid flow can be achieved by pumping, injecting, spraying, or the like steps, the solvents into the hollow columns (4) containing the medium. In addition, the fluid flow into the columns can be achieved by providing a manifold (2).

[0072] The term "column" or "one or more columns" used for carrying out the SX is not particularly limited, and should be understood by a person of skill in the art. In one embodiment, for example and without limitation, the column (4) is a contactor column. A contactor column is a vessel in which liquids or gases have a large area of contact with one another. The number of columns used is not particularly limited, and can be varied based on design and application requirements. In one embodiment, for example and without limitation, the process and/or system (1) utilizes two, three, four, five, six, seven, eight, nine or ten columns. The number of columns noted refer to the number of columns in each stage of the unit operation, with different stages having the same or different number of columns. The use of a plurality of columns makes such systems (1) potentially much easier to site and more efficient to operate. The contactor column (also referred to as "RapidSX™ Contactor" or"RapidSX™ Extractor" herein) contains a randomly packed discontinuous medium (12), i.e. made up of discrete beads or particles, as opposed to fibers running the length of the column, or a foam or porous packing. The discontinuous medium (12) in the RapidSX™ Extractor can have a higher packing density than is typically the case in simple packed columns.

[0073] As described herein, in one embodiment, for example and without limitation, solvents are introduced in one end of the column through orifices. The orifice is employed to help mix the aqueous and organic fluids prior to entry into the packed bed. The object is to help achieve thorough and homogeneous mixing of the solvents; in other words, to increase the Reynolds number, creating turbulent flow of the fluids, allowing them to mix. The size of the orifice selected is dependent on the volumetric flow of the fluid. Lower flows require a smaller orifice in order to help increase the Reynolds number sufficiently to result in adequate mixing. As the flow rate increases the orifice can be increased to avoid having an excessive restriction of flow which can require larger pumps, higher pressures and more energy to overcome. It should be noted that orifices are not required for the functioning of the invention, and other mixing means, such as, for example and without limitation, static type mixers can also be used. Static type mixers and orifice mixing was trialed during testing and orifices selected as these can be changed easily and offer better flexibility than a static type mixer.

[0074] In addition, it should be noted that the mixing head is not necessarily required for the technology to function. Completely unmixed fluids entering the packed bed will mix and stay mixed within the packed bed as long as sufficient fluid velocity is achieved. In one embodiment, for example and without limitation, the fluids entering the packed bed have a fluid velocity equal to or greater than approximately 17.8 mm/s. For example, and without limitation, in a 2 inch diameter contactor column without a mixing head, homogenous mixing was observed to occur after approximately 400 mm of packed bed. Larger diameter contactor columns with a central entry point can require a longer distance for homogeneous mixing to occur. In a further embodiment, for example and without limitation, the velocity of the fluids within the packed bed are kept at or above approximately 17.8 mm/s, to help avoid and minimize separation of the fluids within the contactor.

[0075] Referring back to the embodiment utilizing an orifice, in one embodiment, for example and without limitation, the orifices are of a specific diameter. In a first embodiment, for example and without limitation, the orifice has a diameter of 0.2 mm. In a second embodiment, for example and without limitation, the orifice has a diameter of 0.5mm. In a third embodiment, for example and without limitation, the orifice has a diameter of 1 mm. In a fourth embodiment, for example and without limitation, the orifice has a diameter of 2 mm. In a fifth embodiment, for example and without limitation, the orifice has a diameter of 3 mm. In a sixth embodiment, for example and without limitation, the orifice has a diameter of 5 mm. In a seventh embodiment, for example and without limitation, the orifice has a diameter of 9 mm. There is one orifice for each solvent phase entering the column. Each orifice may be the same diameter. Alternatively, the orifices may be different sizes. In one embodiment, for example and without limitation, the orifices are arranged perpendicular to each other to allow the solvent phases to come in contact before continuing through the column. In a second embodiment, for example and without limitation, the orifices are arranged in a face-to-face relationship to allow the solvent phases to come in contact before continuing through the column.

[0076] As described herein, in one embodiment, for example and without limitation, the column contains randomly packed discontinuous medium, that allows for the first solvent phase and the second solvent phase to come in contact, as the solvent phases flow through the column. The term 'random packing', 'random packed' and the like are not particularly limited and should be known or understood by a person of skill in the art. Random packing uses a random distribution of small packing materials to assist in the separation process, and can help to increase the surface area for the solvent phases to contact one another, allowing mass transfer and extraction to take place. In contrast, structured packing uses larger, fixed packing structures, used to channel liquid material into a specific shape. Structured packing can use, for example, discs or plates that can be attached to the column, and can be composed of materials such as metal, plastic or porcelain with their internal structures arranged into different types of shapes, such as honeycomb, to direct fluid flow in a particular controlled manner.

[0077] The term, 'discontinuous medium' or 'discontinuous packing medium' as used herein is not particularly limited and should be known to or understood by a person of skill in the art. The discontinuous medium as disclosed herein relates to small diameter particles, which lead to small gaps or spaces between the particles, allowing solvent phase flow. This leads to the void spaces (related to void fraction) allowing fluid flow. In addition, the extent of the packing of the discontinuous medium leads to a packing density of the packing medium. In one embodiment, for example and without limitation, the column contains a randomly packed discontinuous packing medium. In another embodiment, for example and without limitation, the discontinuous packing medium can be achieved by additive manufacturing of the column and the packing inside the column, such as, for example and without limitation, by 3D printing of the column and the packing medium having void spaces similar to a randomly packed discontinuous packing medium. The discontinuous packing medium as used herein leads to void spaces, providing the solvent phases a space to interact and allow separation of the target species, as described herein.

[0078] The randomly packed discontinuous medium, as disclosed herein, has a void fraction, due to the gaps or spaces between the particles. Void fraction provides information on the void space in a column bed, and relates to the ratio of the volume of voids in a bed to the total volume of the bed (voids plus solids). In a first embodiment, for example and without limitation, the randomly packed discontinuous medium has a void fraction from 0.30 - 0.44. In second embodiment, for example and without limitation, the randomly packed discontinuous medium has a void fraction from 0.33 - 0.41. In a third embodiment, for example and without limitation, the randomly packed discontinuous medium has a void fraction from 0.36 - 0.38.

[0079] As disclosed herein, the randomly packed discontinuous medium can have a packing density. The term, 'packing density' is not particularly limited and should be known or understood by a person of skill in the art. Packing density or packing fraction of a packing in some space is the fraction of the space filled by the material making up the packing. In other terms, this is the ratio of the volume of bodies in a space to the volume of the space itself. It should be noted that the packing density is also a function of the particle density, where very heavy particles would result in a higher packing density. In a first embodiment, for example and without limitation, the randomly packed discontinuous medium has a packing density from 0.48 - 0.63 g/cm³. In a second embodiment, for example and without limitation, the randomly packed discontinuous medium has a packing density from 0.52 - 0.60 g/cm³. In a third embodiment, for example and without limitation, the randomly packed discontinuous medium has a packing density from 0.55 - 0.57 g/cm³.

[0080] The use of a discontinuous packing medium (12) comprising small diameter particles in the contactor column can help provide intimate contact over a large interfacial area between first and second fluid (or solvent) phases flowing co- currently through the medium, such that high efficiency transfer of target species from the first fluid (solvent) phase to the second fluid (solvent) phase can be attained, without the need for mechanical agitation. The method can help to maximize extraction efficiency while maintaining a dispersion of the first and second fluid (solvent) phases which is easily separable. In Figure 3, the discontinuous medium (12) is shown as a grey coloured section in the column (4), however, to assist with review, similar discontinuous medium (12) is not shown in all the columns in Figures 4-6 (although it is present). [0081] The step of permitting the first solvent phase and the second solvent phase to contact one another is not particularly limited. In one embodiment, the first and second fluid (solvent) phases are directed to flow co-currently through the contactor column. In other words, the first and second solvent phases flow through the contactor column in the same direction as one another, as opposed to flowing in different directions, such as, opposite directions (counter-current). Neither one of the fluid phases is arranged to be constrained on the packing medium.

[0082] The particles of the packing medium are sized to retain the fluid (solvent) phases in the contactor column (4) for a sufficient time to allow diffusion of target species from the first solvent phase to the second solvent phase. If the particle size is too big, the size of the voids in between might be too big, and the solvent phases would exit the column without equilibrium being reached in terms of this diffusion. On the other hand, the particle size should not be so small that fluid flow through the column (4) is impeded because of capillary or viscosity issues. Particle size of the packing medium is therefore selected in accordance with the specific target species and column dimensions of a particular SX application.

[0083] In one embodiment, for example and without limitation, the particles have a diameter of about 5 mm or less. In another embodiment, for example and without limitation, the particles have a diameter of about 0.5 mm to about 5 mm. In a further embodiment, for example and without limitation, the particles have a diameter of about 1 mm to about 4 mm. In still another embodiment, for example and without limitation, the particles have a diameter of about 1.0 mm to about 3.5 mm. In another further embodiment, for example and without limitation, particles having a diameter in the range 1.5-3 mm are particularly suitable for bringing about effective contacting of fluid phases in co-current flow and achieving high efficiency transfer of target species therebetween, while helping to reduce or prevent formation of an emulsion.

[0084] The method disclosed herein affects juxtaposition of the first and second fluid phases with high interfacial surface area contact, without mixing them or by reducing the amount of mixing, while reducing or preventing formation of emulsion. The respective fluid phases are put together in intimate contact but they reduce or avoid being blended or amalgamated, such that, there is no significant discontinuous dispersion of one phase into the other; and/or no significant fraction of one phase is substantially or completely enveloped by the other phase. The constituent phases can generally remain distinct and readily separable. Without wishing to be bound by any particular theory, it is believed that droplets of each of the two phases are interacting with each other as they cascade down the column, but are not emulsified, as described above. This allows extraction of the one or more target species from the first solvent phase to the second solvent phase

[0085] In an embodiment, for example and without limitation, the particles are substantially spherical or ovoid beads. In one embodiment, for example and without limitation, the particles are polymer beads, e.g. polypropylene beads. Polymer beads are relatively light compared to e.g. ceramic or metal beads, which provides advantages in terms of mechanics, handling and logistics. Polypropylene is hydrophobic and therefore will repel water and aqueous solutions and attract oils and organic solutions. In one embodiment, for example and without limitation, the particles are glass beads. Glass is hydrophilic and therefore will attract water and aqueous solutions and repel oils and organic solutions. The choice of material for the particles in the column changes the function of the column packing and can help improve the solvent extraction efficiency. In a further embodiment, multiple materials are selected for use as particles in the columns, and can be segregated in zones based on the physical-chemical properties. As such, in one embodiment, for example and without limitation, the contactor column (4) has a first zone (30) containing a first discontinuous medium and a second zone (32) containing a second discontinuous medium, wherein the first discontinuous medium comprises hydrophobic particles and the second discontinuous medium comprises hydrophilic particles (Figure 6). When multiple zones are present, the first zone (30) and the second zone (32) can be present in a single contactor column (4), or the first zone (30) and the second zone (32) can be present in separate contactor columns (4), when the stage operation contains multiple columns (4) (as shown in Figure 6). [0086] In one embodiment, as shown in Figures 4 and 6, the two phases enter the Stage at the top of each column (4) and thus flow in a co-current manner from top to bottom, inside each column (4). In each column (4) for a Stage that utilizes more than one column (4), this co-current flow occurs simultaneously and in parallel, within each column (4). The same SX unit operations are utilized, with no changes to the Aqueous or Organic Phases used. The entry of the solvent phases in the one or more columns (4) can be carried out using a manifold (2); and where the manifold (2) is coupled to the one or more columns (4), being in fluid communication with the one or more columns (4), permitting flow of the first solvent phase and/or the second solvent phase to enter the one or more columns (4).

[0087] The use of co-current flow of the liquids differs from most other column-based methods. Co-current flow is able to be used because the beads in the column provide surface area for contact of the two immiscible liquid phases at a higher flow rate. This permits the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase. Also, because the beads do not work on capillary effects, this can help to ensure that the flow of the phases can be maximized. This approach can be problematic for applications that utilize fibre based contactors, since the capillary action results in slow fluid flow. A countercurrent flow will not enhance this kind of mixing and will likely require assistance from mechanical agitation. In addition, the use of co-current flow can help to improve the rate and degree of subsequent separation of the two phases after mixing. The mixing and demixing of the phases can be optimized to reduce settling time, as overmixing can result in a very long settling time, which would have a negative impact on the overall throughput of a plant. Such an advantage can be achieved through the use of beads in the column (4). The two (co-current flow and beads) work in tandem to help provide maximum throughput while also maximizing transport. [0088] In addition, the use of beads as opposed to larger saddles or other packing shapes means that there is more physical mobility of the wetted surface of the bead and therefore improved mass transport between the wetted phase and the non-wetted phase.

[0089] The presence of the beads in the column (4) forces the Phases to cascade and to interact with each other, on the surface of the beads as well as in the spaces between them. This approach can help increase the specific area of the interface between the two Phases during contact in each RapidSX™ Contactor, compared to the specific area of the same interface using conventional Mixers in Mixer-Settler Contactors. This increased specific area can increase the overall rate of mass transfer (such as, diffusion of metal ions) between the two Phases.

[0090] At the same time, the contacting of the Phases occurs without agitation, and without any significant discontinuous dispersion of one Phase into the other. This leads to a significant reduction in the time that it takes for the two Phases to settle or coalesce, after contacting, and significantly reduces entrainment (the aforementioned permanent and nuisance dispersion of droplets of one Phase inside the other).

[0091] The combination of improvements disclosed herein can lead to a significant reduction in the overall time that it takes for the process to go to completion in each RapidSX™ Contactor, compared to a Mixer-Settler Contactor.

[0092] Referring to the figures now to further elucidate embodiments disclosed in the specification, Figure 3 shows a schematic of a RapidSX™ Contactor (1), with one column (4) and one Settler (6). The aqueous phase, which in the extraction unit operation can be the first solvent phase and shown with a solid line, enters the manifold (2). Similar to the aqueous phase, the organic phase, which in the extraction unit operation can be the second solvent phase and shown with a dashed line, enters the manifold (2). The manifold (2) set-up is not particularly limited and can be varied depending upon design and application requirements. For example and without limitation, the first solvent phase and the second solvent phase can be allowed to mix before entry into the column (4). Alternatively, the first solvent phase and the second solvent phase in the manifold (2) can be kept separated, and mixing of the first solvent phase and the second solvent phase occurs upon entry into the column (4).

[0093] The first solvent phase and the second solvent phase then enters the top end (14) of an upright column (4), exiting the manifold (2), and flows downward in the column passing through the discontinuous packing medium (12). Positioning of the column (4) vertically allows gravitational flow of the first and second solvent phases, from the top end (14) of the column (4) towards the bottom end (16) of the column (4). As the solvent phases passes from the top end (14) towards the bottom end (16) of the column (4), the solvent phases flows in spaces in between the discontinuous packing medium (12), leading to contact between the phases, and extraction of the one or more target species from the first solvent phase to the second solvent phase. Although the embodiments in the Figures, relate to an upright column, positioned vertically from the ground, it should be noted that other positions are possible and encompassed within the specification, such as, where the column being horizontally positioned. In such an embodiment, the first solvent phase and the second solvent phase then enter the column from a first end of the column and exit from a second end.

[0094] Once the solvent phases exit the discontinuous packing medium (12), they flow into a settler (6), where separation of the first solvent phase and the second solvent phase can take place. In one embodiment, as shown in Figure 3, the column (4) is coupled to the settler (6) via a joint (18) that allows fluid communication between the column (4) and the settler (6). The first and second solvent phases flow from the column (4), passing through the joint (18), into the settler (6). Once in the settler (6), the first solvent phase and the second solvent phase separate. Upon separation, one of the solvent phases can be removed from a first end (20) of the settler (6), and the other solvent phases can be removed from a second end (22) of the settler (6). In the embodiment shown in Figure 3, as the aqueous phase is the first solvent phase, is heavier than the organic (second solvent) phase, the aqueous (first solvent) phase can be removed from the first end (20) of the settler (6), and the organic (second solvent) phase can be removed from the second end (22) of the settler (6). In one embodiment, for example and without limitation, the settler (6) as shown in Figure 3 is positioned vertically.

[0095] Figure 4 shows another embodiment of the system (1) in accordance with the specification. The system (1) shown in Figure 4 operates similar to the system (1) shown in Figure 3, with some of the differences disclosed herein. In Figure 4, the manifold (2) is fluidly coupled to multiple column (4). Hence, the first and second solvent phases flow from the manifold (2) into multiple columns (4). In the embodiment shown in Figure 4, four columns (4) each containing discontinuous packing medium (12) is provided, and separate fractions of the first and second solvent phases flow through the columns (4). In addition, the bottom end (16) of the columns (4) opens into a single settler (6). Consequently, no joint is required in the system (1) configuration shown in Figure 4. Further, as the bottom end (16) of the columns (4) opens into a single settler (6), all fractions of the first and second solvent phases that flow through the different columns combine, and then the first and second solvent phases separate in the settler (6). In one embodiment, for example and without limitation, as shown in Figure 4, the settler (6) is provided with a weir system (24) that helps to direct the first and second solvent phases after separation from the settler (6) to an separate exit ports (not shown) (for the first and second solvent phases) from the settler (6). The weir system used is not particularly limited and should be known to a person of skill in the art. The weir system can help in separating the first and second solvent phases. In one embodiment, for example and without limitation, the settler (6) disclosed in Figure 4 is horizontally positioned (compare to the settler (6) shown in Figure 3), having a longer length than height. Such a settler (6) can help with increasing the rate of separation of the first and second solvent phases.

[0096] Figure 5 shows a further embodiment of the system (1) in accordance with the specification. Figure 5 is similar to the system (1) shown in Figure 3 with the difference that the system (1) of Figure 5 is provided with a first solvent system recycling valve (10, also described as the aqueous recycle valve) and a second solvent system recycling valve (8, also described as the organic recycle valve). The organic solvent system recycling valve (8) allows recycling of the organic solvent phase, while the aqueous solvent system recycling valve (10) allows recycling of the aqueous solvent phase. After separation of the first and second solvent phases in the settler (6), the recycling valves (8, 10) can re-direct the first and second solvent phases to an injection system (26). From the injection system (26), the first and second solvent phases re-enter the manifold. Various options are available with the use of the recycling valves (8, 10), including only one of the solvent phases being recycled, and/or a portion of the solvent phases being recycled. The recycling valves (8, 10) are also provided with features that allow redirecting the solvent phases to separate containers for further processing.

[0097] In addition to the above, in one embodiment, for example and without limitation, as shown in the embodiment shown in Figure 5, the process and system disclosed herein is provided with a coalescer (28) positioned downstream of the discontinuous packing medium (12). In a further embodiment, for example and without limitation, the coalescer (28) is positioned in the joint (18) connecting the column (4) to the settler (6). In a still further embodiment, for example and without limitation, the coalescer (28) is present as a cartridge. In another embodiment, for example and without limitation, the process further contains the step of coalescing the first solvent phase and the second solvent phase.

[0098] The type of coalescer used is not particularly limited, and should be known to a person of skill in the art. In one embodiment, for example and without limitation, a mechanical coalescer is used. In another embodiment, for example and without limitation, the coalescer is an electro-mechanical coalescer.

[0099] The step of coalescing as used herein is not particularly limited. In one embodiment, for example and without limitation, the step can involve passing the first solvent phase and the second solvent phase through a further packing medium. The further packing medium can be placed in a cartridge and can help to act as a coalescer to reduce the phase separation times under certain conditions, and thereby improve solvent extraction process efficiency. In one embodiment, for example and without limitation, the packing medium used for coalescing the first solvent phase and the second solvent phase is is glass wool. In another embodiment, for example and without limitation, the glass wool used is made of silicon dioxide (SiOz). In a further embodiment, for example and without limitation, the glass wool can be amorphous or quartz (crystalline). In another further embodiment, for example and without limitation, the glass wool is packed at a density ranging from about 0.07 to about 0.1 g of glass wool/cm³.

[OO1OO] The term, cartridge, as used herein is not particularly limited and should be understood by a person of skill in the art. The cartridge provided can be a section of the mixer-settler containing the further packing medium or provided as a separate housing that contains the further packing medium. In addition, for example and without limitation, the further packing medium could be replaced with a fibrous medium to increase surface area. In addition, for example and without limitation, the further packing medium or fibrous medium can be a hydrophilic media. Non-limiting examples of hydrophilic media include glass wool or beads.

[00101] Figure 6 shows a further embodiment of the system (1) in accordance with the specification. Figure 6 is similar to the system (1) shown in Figure 4 but has the added feature of recycling valves (8, 10) as shown and described in Figure 5. In addition, the embodiment shown in Figure 6(A&B) shows a contactor column (4) containing a first zone (30) containing a first discontinuous media present in a first contactor column (4) of a stage and a second zone (32) containing a second discontinuous media present in a second contactor column (4) of the same stage (difference between first and second discontinuous media shown in Figure 6 based on grey shading).

[00102] Figure 7 shows a SX operation containing the multiple unit operations for carrying out the solvent extraction, as described herein. The use of the method and system disclosed herein is not particularly limited to the extraction step (EXI, EX2 or EX3), but can also be used in the other unit operations (such as, scrub (SCI, SC2), strip (STI, ST2), wash (WAI) or pre-neutralization (PN1)) depending upon design and process requirements. In the embodiment disclosed herein, the system (100) has been described with respect to the extraction step, where the first solvent phase (aqueous phase) containing the one or more target species enters EX3 (for example and without limitation), along with a portion of the second solvent (organic) phase. After flowing through the one or more columns (4), the solvent phases separate in a settler (6), with the first solvent phase directed to a second system (EX2), where it mixes with a second portion of the second solvent phase, for further extraction. This continues in a third system (EXI), with the first solvent phase exiting as the aqueous raffinate. The different portions of the second solvent (organic) phases can undergo subsequent treatment in other unit operations of the solvent extraction operation, as disclosed herein.

[00103] Furthermore, the overall working volume of the RapidSX™ Contactor can be significantly lower than that for Mixer-Settler Contactors, since the two Phases can move through the RapidSX™ Contactor at a much faster rate than the equivalent Mixer-Settler Contactor, while maintaining separation performance. Due to faster separation times, the settler portion of the unit can be smaller in size, which reduces the working volume. In addition, less Organic can be used in the overall circuit, compared to conventional SX circuits, and less physical inventory of Feed Solutions can be tied up in the circuit at any one time.

[00104] This combination means that the overall size, physical footprint and capital costs for the associated SX circuit can also be significantly reduced.

[00105] As shown in Figure 7, the organic phase (or pre-neutralized organic phase) (106) enter extraction stage 1 (EXI) via inlet B01 of the extraction unit operation in the solvent extraction system (100). Flow of the organic phase (106) in Figure 7 is disclosed using dashed arrows, while flow of the aqueous fluid or feed solution (102) is shown using solid arrows. After completion of extraction in extraction stage 1 (EXI), the organic phase (106) flows into extraction stage 2 (EX2) via tubing or other connection (B02). Extraction stage 2 (EX2) is connected to extraction stage 3 (EX3) via a connection (B03) that allows flow of the organic phase (106) from extraction stage 2 (EX2) to extraction stage 3 (EX3). [00106] In the solvent extraction system (100) disclosed in Figure 7, the feed solution (102) enters the system (100) via an inlet port (A01) in extraction stage 3 (EX3). Sodium hydroxide (NaOH) can also be added to the extraction stage 3 (EX3) via inlet port (A16) to control the pH of the phases. Controlling of pH can assist in better selectivity in binding of the extractant to the desired metal or other species. In addition, the sodium hydroxide (NaOH) can help neutralize any excess hydrochloric acid (HCI) (that may be present in extraction stage 3 (EX3)) entering from the scrubbing unit operation, as described herein.

[00107] From extraction stage 3 (EX3), the feed solution (102) flows into the extraction stage 2 (EX2) via a connection tubing or other connector (A02). After flowing through extraction stage 2 (EX2), the aqueous solution (102) flows via a connection (A03), which allows fluid flow from extraction stage EX2 to extraction stage 1 (EXI). After settling in the extraction stage 1, the aqueous phase is removed as raffinate (108) via outlet (A04).

[00108] In the extraction unit operation of the solvent extraction system (100), three extraction stages (EXI, EX2 and EX3) have been provided. The organic phase (106) flows counter to the aqueous phase or feed solution (102) in the extraction unit operation of the solvent extraction system (100), with the organic phase (106) flowing from EXI

EX3, while the aqueous phase or feed solution (102) flowing from EX3 -> EX2 -> EXI. Although the flow of the organic solution (106) is counter to the flow of the aqueous phase or feed solution (102) in the solvent extraction system, in each extraction stage (EXI, EX2 or EX3), the flow of the organic solution (106) and the aqueous phase or feed solution (102) is cocurrent (in the same direction), as disclosed herein.

[00109] In the solvent extraction system (100), the scrubbing (denoted by 'SC') unit operation is performed in two stages (SCI and SC2). The organic phase (102) from extraction stage 3 (EX3) exits the extraction unit operation and enters scrubbing stage 1 (SCI) via a connection (B04) that allows fluid flow from extraction stage 3 (EX3) to scrubbing stage 1 (SCI). After completion of the scrubbing stage 1 (SCI) operation, the organic phase (106) flows from scrubbing stage 1 (SCI) to scrubbing stage 2 (SC2) via a connection (B05). In scrubbing stage 2 (SC2), hydrochloric acid (HCI) can be added via port (A05), which then flows into scrubbing stage 1 (SCI) via connection (A06), after completion of the scrubbing stage 2 (SC2) operation. Analogous to the extraction unit, flow of the organic and aqueous phases is counter to each in the overall system (100), however, the flow can be co-current in each stage (SCI or SC2), as disclosed herein, for removal of impurities during the scrubbing unit operation. Upon completion of scrubbing stage 1 (SCI), the scrubbing HCI solution can be added to extraction stage 3 (EX3) via connection (A07).

[OO11O] The acid used in the scrubbing stage is not particularly limited and can be varied depending upon design and application requirements. By addition of the acid, pH of the unit operation is adjusted to help with further selectivity and thereby purification of the target species.

[00111] In the solvent extraction system (100), the stripping (denoted by 'ST') unit operation is performed in two stages (STI and ST2). The organic phase (102) from scrubbing stage 2 (SC2) exits the scrubbing unit operation and enters stripping stage 1 (STI) via a connection (B06) that allows fluid flow from scrubbing stage 2 (SC2) to stripping stage 1 (STI). After completion of the stripping stage 1 (STI) operation, the organic phase (106) flows from stripping stage 1 (STI) to stripping stage 2 (ST2) via a connection (B07). The stripping solution containing HCI is formulated in stripping solution formulation unit (STF), which receives HCI via port A08 and an aqueous phase from the washing stage 1 (WAI), which flows from the washing stage 1 (WAI) to the stripping solution formulation unit (STF) via a connection (A13), to formulate the stripping the solution. The stripping solution flows from the stripping solution formulation unit (STF) to the stripping stage 2 (ST2) via a connection (A09), where one of the stripping stages is carried out.

Once complete, the aqueous solution flows from stripping stage 2 (ST2) via a connection (AID) to stripping stage 1 (STI). After completion of the stripping stage 1, the aqueous rich strip (116) exits stripping stage 1 (STI) via a port (All). Similar to the other unit operations, the organic phase flow between the stages (STI and ST2) of the stripping unit operation is opposed to the flow of the aqueous solution, while in each unit operation (STI or ST2), the flow of the two phases can be co-current (or in the same direction).

[00112] Similar to the scrubbing stage, the acid used in the stripping stage is not particularly limited and can be varied depending upon design and application requirements. By addition of the further acid, pH of the stripping unit operation is adjusted to help with extraction of the target species from the organic phase into the aqueous phase. This step also helps in regeneration of the organic phase, which upon further treatment can be recycled in the process.

[00113] In the solvent extraction system (100), the washing (denoted by 'WA') unit operation is performed in one stage (WAI), however, it should be noted that additional stages, such as, for example and without limitation, two, three, four, five or six, are encompassed within the technology disclosed herein. The organic phase (102) from stripping stage 2 (ST2) exits the stripping unit operation and enters wash stage 1 (WAI) via a connection (B08) that allows fluid flow from stripping stage 2 (ST2) to washing stage 1 (WAI). In the washing stage 1 (WAI), water (H2O) can be added via port (A12), and after completion of the washing stage 1 (WAI), the aqueous phase flows from washing stage 1 (WAI) via a connection (A13) to the stripping solution formulation unit (STF).

[00114] Once the washing unit operation is complete, the organic phase (106) flows from the washing stage 1 (WAI) to the pre-neutralization stage 1 (PN1) via a connection (B09). Sodium hydroxide (NaOH) can be added to the preneutralization stage 1 (PN1) via port (A14) to neutralize the acidity of the organic phase (106). After completion of the pre-neutralization stage 1 (PN1), the aqueous phase exits the pre-neutralization stage 1 (PN1) via connection (A15) and enter the washing stage 1 (WAI), while the organic phase (106) exits the system via an outlet (BIO). The organic phase (106) can be recycled back to the extraction stage 1 (EXI) via inlet (B01).

[00115] As should be understood by the disclosure herein, the first and second solvent phases vary depending upon the unit operation being carried out. In the extraction stage, where the target species are present in the aqueous phase, the first solvent phase is the aqueous phase, while the second solvent phase is the organic phase. This, however, reverses in subsequent unit operations. For instance, in the stripping unit operation, the organic phase has the target species, and as such will be the first solvent phase, while the aqueous phase will be the second solvent phase.

[00116] In a further aspect, the specification relates to a process for purification of one or more target species, the process comprising:

[00117] an extraction step in fluid communication with a scrubbing step, and a stripping step in fluid communication with the scrubbing step,

[00118] wherein at least one of the extraction step, scrubbing step and the stripping step comprises the method as disclosed herein.

[00119] In a still further aspect, the specification relates to a system for purification of one or more target species, the system comprising:

[00120] an extraction stage in fluid communication with a scrubbing stage, and a stripping stage in fluid communication with the scrubbing stage,

[00121] wherein at least one of the extraction stage, scrubbing stage and the stripping stage comprises the system as disclosed herein.

[00122] The extraction step, scrubbing step, stripping step, and other steps, such as, the washing step or pre-neutralization steps, are not particularly limited and should be understood by a person of skill in the art. These steps involve the respective stages described herein above for extraction of target species, where appropriate process steps are carried out using the method and system disclosed herein.

[00123] The method and system disclosed herein can help to improve the kinetics of metal-ion transfer during the contacting of the Aqueous and Organic Phases. This is achieved by replacing the conventional Mixer-Settler Contactor with a combination of one or more columns with a settler in each Stage (i.e. a "RapidSX™ Contactor"), as disclosed herein. In addition, the method and system disclosed herein can help to achieve near plug flow behaviour, which means all solutions are mixed for almost same amount of time. This is different from conventional mixer and settlers where a distribution of residence times is encountered, and to achieve high separation and purity targets, the mixer contactor is oversized to ensure solution is adequately mixed.

[00124] EXAMPLES

[00125] The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific Examples. These Examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the following illustrative examples, make and utilize the constructs of the present invention and practice the claimed methods. The following working examples therefore, specifically point out the typical aspects of the present invention and are not to be construed as limiting in any way in the remainder of the disclosure. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation.

[00126] Example 1: Use of a set of RapidSX™ Contactors for the separation of REEs.

[00127] An SX circuit using single-column RapidSX™ Contactors of the type shown in Figure 3, was Staged as shown in Figure 7. The SX circuit comprised three Extract Stages (EXI, EX2, and EX3), two Scrub Stages (SCI and SC2) , two Strip Stages (STI and ST2), one Strip Feed box (STF), one Wash Stage (WAI) and one Pre-Neutralization Stage (PN1). Each RapidSX™ Contactor utilized a 10-foot PVC column, 2" in diameter, which was packed with spherical polypropylene beads 3mm in diameter. Perforated plates were inserted at the top and bottom of each column to keep the beads in place. Each column was connected to a 2-foot PVC column, 4" in diameter. Incoming Aqueous and Organic Phases were brought into the top of each column via flexible hosing. The outgoing Aqueous and Organic Phases were brought out of the bottom and top of the Settler respectively via flexible hosing.

[00128] The Pre-Neutralized Organic Phase entered Stage EXI and flowed through each successive Stage before coming back into Stage EXI. The aqueous Feed Solution entered Stage EX3 and flowed to Stages EX2 and EXI, before exiting Stage EXI as the aqueous Raffinate. Small quantities of 50% NaOH also entered Stage EX3 as a means of controlling pH during Extract.

[00129] Dilute HCI was used as the scrubbing solution and entered at Stage SC2, flowing to Stage SCI before exiting from Stage SCI into Stage EX3.

[00130] A stripping solution comprising 5N HCI and the output of the Wash unit operation were mixed in the Strip Feed box before entering into Stage ST2, from which it flowed into Stage STI and exited as the aqueous Rich Strip solution.

[00131] Water entered the Wash unit operation at Stage WAI, before exiting into the Strip Feed box.

[00132] Dilute NaOH entered the Pre-Neutralization unit operation via Stage PN1, before exiting into Stage WAI.

[00133] The specific purpose of the SX circuit described above was the separation of the REEs La-Ce-Pr-Nd from the REEs Sm-Eu-Gd-Tb-Dy-Ho-Er-Tm-Yb- Lu-Y. The assay of the initial Ce-depleted chloride-based Feed Solution in parts per million (ppm) and the relative distribution of the REEs as a percentage of total REEs (TREEs) is shown in Table 1.

Table 1. Assay of the initial Feed Solution and the relative distribution of the REEs.

[00134] The Organic Phase consisted of 33 volume % Cyanex® 572 extractant dissolved into Exxon D80. The flow-rate ratio between the Organic and Aqueous Phases through the Extract unit operation was set at 4: 1, with the Organic Phase flowing through the Circuit at a rate of 1.2 L / minute.

[00135] The assay of the resulting Raffinate in terms of ppm and the relative distribution of the REEs is shown in Table 2. The purity of the raffinate with respect to the target La-Ce-Pr-Nd elements compared to TREEs present was 99.9%.

Table 2. Assay of the resulting raffinate and the relative distribution of the REEs.

[00136] All publications, patents and patent applications cited above are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

EMBODIMENTS

[00137] 1. A method for separation of one or more target species from a first solvent phase, the method comprising:

[00138] passing the first solvent phase containing the one or more target species, and a first portion of a second solvent phase, through a first set of one or more columns containing discontinuous packing medium, wherein the first solvent phase and second solvent phase are immiscible with one another, and flow of the first solvent phase and the second solvent phase through the first set of one or more columns is co-current; and

[00139] permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase. [00140] 2. The method of embodiment 1, wherein the first set of one or more columns is upright and flow of the first solvent phase and the second solvent phase is downwards.

[00141] 3. The method of embodiment 1 or 2, wherein the discontinuous packing medium comprises a first zone containing a first discontinuous media and a second zone containing a second discontinuous media, and wherein the first discontinuous media comprises hydrophobic particles and the second discontinuous media comprises hydrophilic particles.

[00142] 4. The method of embodiment 1 or 2, wherein the particles have a diameter of about 5 mm or less.

[00143] 5. The method of embodiment 4, wherein the particles have a diameter in the range of about 1 to about 3 mm.

[00144] 6. The method according to any one of embodiments 1 to 5, wherein the particles are substantially spherical or ovoid beads.

[00145] 7. The method according to embodiment 6, wherein the beads are polymer beads or glass beads.

[00146] 8. The method of any one of embodiments 1 to 7, wherein the one or more columns is a contactor column.

[00147] 9. The method of any one of embodiments 1 to 8, further comprising the step of passing the first solvent phase and the second solvent phase through a coalescer to coalesce the first solvent phase and the second solvent phase.

[00148] 10. The method of embodiment 9, wherein the coalescer comprises a further discontinuous medium. [00149] 11. The method of embodiment 10, wherein the further discontinuous medium is present in a cartridge.

[00150] 12. The method of any one of embodiments 1 to 11, further comprising separating the first solvent phase and the second solvent phase after passing through the first set of one or more columns.

[00151] 13. The method of embodiment 12, further comprising the step of recycling the first solvent phase and/or the second solvent phase.

[00152] 14. The method of embodiment 12 or 13, further comprising:

[00153] passing the first solvent phase, and a second portion of the second solvent phase, through a second set of one or more columns containing discontinuous packing medium, wherein flow of the first solvent phase and the second solvent phase is co-current; and

[00154] permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase.

[00155] 15. The method of embodiment 14, further comprising separating the first solvent phase and the second solvent phase after passing through the second set of one or more columns.

[00156] 16. The method of embodiment 15, further comprising the step of recycling the first solvent phase and/or the second solvent phase.

[00157] 17. A system for extraction of one or more target species from a first solvent phase to a second solvent phase, the system comprising: [00158] a first set of one or more columns containing discontinuous packing medium,

[00159] wherein the system is configured for co-current flow of the first solvent phase and the second solvent phase in the first set of one or more columns, and permits contact of the first solvent phase with the second solvent phase as the solvents flow through the discontinuous packing medium.

[00160] 18. The system of embodiment 17, wherein the first set of one or more columns is upright and is configured for downward flow of the first solvent phase and the second solvent phase.

[00161] 19. The system of embodiment 17 or 18, further comprising a manifold for permitting flow of the first solvent phase and/or the second solvent phase to the first set of one or more columns.

[00162] 20. The system of any one of embodiments 17 to 19, wherein the particles have a diameter of about 5 mm or less.

[00163] 21. The system of embodiment 20, wherein the particles have a diameter in the range of about 1 to about 3 mm.

[00164] 22. The system according to any one of embodiments 17 to 21, wherein the particles are substantially spherical or ovoid beads.

[00165] 23. The system according to embodiment 22, wherein the beads are polymer beads or glass beads.

[00166] 24. The system of any one of embodiments 17 to 23, wherein the one or more columns is a contactor column. [00167] 25. The system of any one of embodiments 17 to 24, further comprising a coalescer positioned downstream from the first set of one or more columns, wherein the coalescer coalesces the first solvent phase and the second solvent phase.

[00168] 26. The system of embodiment 25, wherein the coalescer comprises further discontinuous medium.

[00169] 27. The system of embodiment 26, wherein the further discontinuous medium is present in a cartridge.

[00170] 28. The system of embodiment 26 or 27, wherein the further discontinuous medium is a hydrophilic discontinuous medium.

[00171] 29. The system of embodiment 26 or 27, wherein the further discontinuous medium is a hydrophobic discontinuous medium.

[00172] 30. The system of any one of embodiments 17 to 29, further comprising a first settler tank permitting separation of the first solvent phase and the second solvent phase after passing through the first set of one or more columns.

[00173] 31. The system of embodiment 30, further comprising a recycle control means in fluid communication with the first settler tank permitting recycling of a separated first solvent phase and/or a separated second solvent phase after passing through the first set of one or more columns.

[00174] 32. The system of embodiment 30 or 31, further comprising:

[00175] a second set of one or more columns containing discontinuous packing medium, [00176] wherein the system is configured for co-current flow of the first solvent phase and the second solvent phase, and permits contact of the first solvent phase with the second solvent phase as the solvents flow through the discontinuous packing medium.

[00177] 33. The system of embodiment 32, further comprising a second settler tank permitting separation of the first solvent phase and the second solvent phase after passing through the second set of one or more columns.

[00178] 34. The system of embodiment 32, further comprising a recycle control means in fluid communication with the second settler tank permitting recycling of a separated first solvent phase and/or a separated second solvent phase after passing through the second set of one or more columns.

[00179] 35. A process for purification of one or more target species, the process comprising:

[00180] an extraction step in fluid communication with a scrubbing step, and a stripping step in fluid communication with the scrubbing step,

[00181] wherein at least one of the extraction step, scrubbing step and the stripping step comprises the method as defined in any one of embodiments 1 to 16.

[00182] 36. The process of embodiment 35, further comprising a wash step in fluid communication with the stripping step, and a pre-neutralization step in fluid communication with the wash step.

[00183] 37. The process of embodiment 36, wherein at least one of the wash step and the pre-neutralization step comprises the method as defined in any one of embodiments 1 to 16.

[00184] 38. A system for purification of one or more target species, the system comprising:

[00185] an extraction stage in fluid communication with a scrubbing stage, and a stripping stage in fluid communication with the scrubbing stage, [00186] wherein at least one of the extraction stage, scrubbing stage and the stripping stage comprises the system as defined in any one of embodiments 17 to 34.

[00187] 39. The system of embodiment 38, further comprising a wash stage in fluid communication with the stripping stage, and a pre-neutralization stage in fluid communication with the wash stage.

[00188] 40. The system of embodiment 39, wherein at least one of the wash stage and the pre-neutralization stage comprises the system as defined in any one of embodiment 17 to 34.

[00189] Although preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.

Table of reference numerals

Claims

WHAT IS CLAIMED IS:

1. A method for separation of one or more target species from a first solvent phase, the method comprising: passing the first solvent phase containing the one or more target species, and a first portion of a second solvent phase, through a first set of one or more columns containing discontinuous packing medium, wherein the first solvent phase and second solvent phase are immiscible with one another, and flow of the first solvent phase and the second solvent phase is co-current; and permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase.

2. The method of claim 1, wherein the first set of one or more columns is upright and flow of the first solvent phase and the second solvent phase is downwards.

3. The method of claim 1 or 2, wherein the discontinuous packing medium comprises a first zone containing a first discontinuous media and a second zone containing a second discontinuous media, and wherein the first discontinuous media comprises hydrophobic particles and the second discontinuous media comprises hydrophilic particles.

4. The method of any one of claims 1 to 3, wherein the discontinuous packing medium comprises particles having a diameter of about 5 mm or less.

5. The method of claim 4, wherein the particles have a diameter in the range of from about 1 to about 3 mm.

6. The method according to any one of claims 1 to 5, wherein the particles are substantially spherical or ovoid beads.

7. The method according to claim 6, wherein the beads are polymer beads.

8. The method of any one of claims 1 to 7, wherein the one or more columns is a contactor column.

9. The method of any one of embodiments 1 to 7, further comprising the step of passing the first solvent phase and the second solvent phase through a coalescer to coalesce the first solvent phase and the second solvent phase.

10. The method of claim 9, wherein the coalescer comprises a further packing medium.

11. The method of claim 10, wherein the further packing medium is present in a cartridge.

12. The method of any one of claims 1 to 11, further comprising separating the first solvent phase and the second solvent phase after passing through the first set of one or more columns.

13. The method of claim 12, further comprising the step of recycling the first solvent phase and/or the second solvent phase.

14. The method of claim 12 or 13, further comprising: passing the first solvent phase, and a second portion of the second solvent phase, through a second set of one or more columns containing discontinuous packing medium, wherein flow of the first solvent phase and the second solvent phase is co-current; and permitting the first solvent phase and the second solvent phase to contact one another to allow extraction of the one or more target species from the first solvent phase to the second solvent phase.

15. The method of claim 14, further comprising separating the first solvent phase and the second solvent phase after passing through the second set of one or more columns.

16. The method of claim 15, further comprising the step of recycling the first solvent phase and/or the second solvent phase.

17. A system for extraction of one or more target species from a first solvent phase to a second solvent phase, the system comprising: a first set of one or more columns containing discontinuous packing medium, wherein the system is configured for co-current flow of the first solvent phase and the second solvent phase in the first set of one or more columns, and permits contact of the first solvent phase with the second solvent phase as the solvents flow through the discontinuous packing medium.

18. The system of claim 17, wherein the first set of one or more columns is upright and is configured for downward flow of the first solvent phase and the second solvent phase.

19. The system of claim 17 or 18, further comprising a manifold for permitting flow of the first solvent phase and/or the second solvent phase to the first set of one or more columns.

20. The system of any one of claims 17 to 19, wherein the particles have a diameter of about 5 mm or less.

21. The system of claim 20, wherein the particles have a diameter in the range of about 1 to about 3 mm.

22. The system according to any one of claims 17 to 21, wherein the particles are substantially spherical or ovoid beads.

23. The system according to claim 22, wherein the beads are polymer beads.

24. The system of any one of claims 17 to 23, wherein the one or more columns is a contactor column.

25. The system of any one of claims 17 to 24, further comprising a coalescer positioned downstream from the first set of one or more columns, wherein the coalescer coalesces the first solvent phase and the second solvent phase.

26. The system of embodiment 25, wherein the coalescer comprises further packing medium.

27. The system of embodiment 26, wherein the further packing medium is present in a cartridge.

28. The system of embodiment 26 or 27, wherein the further packing medium is a hydrophilic discontinuous medium.

29. The system of embodiment 26 or 27, wherein the further packing medium is a hydrophobic discontinuous medium.

30. The system of any one of claims 17 to 29, further comprising a first settler tank permitting separation of the first solvent phase and the second solvent phase after passing through the first set of one or more columns.

31. The system of claim 30, further comprising a recycle control means in fluid communication with the first settler tank permitting recycling of a separated first solvent phase and/or a separated second solvent phase after passing through the first set of one or more columns.

32. The system of claim 30 or 31, further comprising: a second set of one or more columns containing discontinuous packing medium, wherein the system is configured for co-current flow of the first solvent phase and the second solvent phase, and permits contact of the first solvent phase with the second solvent phase as the solvents flow through the discontinuous packing medium.

33. The system of claim 32, further comprising a second settler tank permitting separation of the first solvent phase and the second solvent phase after passing through the second set of one or more columns.

34. The system of claim 33, further comprising a recycle control means in fluid communication with the second settler tank permitting recycling of a separated first solvent phase and/or a separated second solvent phase after passing through the second set of one or more columns.

35. A process for purification of one or more target species, the process comprising: an extraction step in fluid communication with a scrubbing step, and a stripping step in fluid communication with the scrubbing step, wherein at least one of the extraction step, scrubbing step and the stripping step comprises the method as defined in any one of claims 1 to 16.

36. The process of claim 35, further comprising a wash step in fluid communication with the stripping step, and a pre-neutralization step in fluid communication with the wash step.

37. The process of claim 36, wherein at least one of the wash step and the preneutralization step comprises the method as defined in any one of claims 1 to

38. A system for purification of one or more target species, the system comprising: an extraction stage in fluid communication with a scrubbing stage, and a stripping stage in fluid communication with the scrubbing stage, wherein at least one of the extraction stage, scrubbing stage and the stripping stage comprises the system as defined in any one of claims 17 to 34.

39. The system of claim 38, further comprising a wash stage in fluid communication with the stripping stage, and a pre-neutralization stage in fluid communication with the wash stage.

40. The system of claim 39, wherein at least one of the wash stage and the preneutralization stage comprises the system as defined in any one of claims 17 to 34.