Chromatographic separation and purification of elemental metals

Abstract

The present invention relates to laboratory to industrial scale (small to industrial) extraction chromatographic separation of rare earth elements (REEs) and platinum group metals (PGMs) and relates to the manufacture of extraction columns and development of stationary phases with substantially improved capacity (i.e., the amount of material purified in a single chromatographic run). More specifically, the present invention relates to the manufacture of extraction columns and stationary phases for the extraction of REEs or PGMs (REEs or PGMs as a group derived from comprising matrices of typical REE or PGM feedstocks) and the separation and purification of the REEs or PGMs individually from each other.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 290,829, filed December 17, 2021, the entirety of which is incorporated by reference in this disclosure.

[0002] (Technical field) The present invention relates to a stationary phase for an extraction column, to the preparation of such a stationary phase, to an extraction column comprising such a stationary phase, and to a method for the preparation of such an extraction column. Such extraction columns have substantially improved capacity with respect to the amount of material purified in one (or single) chromatographic run (or execution). In particular, such extraction columns are useful for small-scale and industrial-scale extraction and chromatographic separation of rare earth elements (REEs) and / or platinum group metals (PGMs).

[0003] More specifically, the present invention relates to the manufacture (or preparation or provision or formation) of stationary phases and extraction columns for: (i) a method for preparing a stationary phase; (i) Extraction of REEs or PGMs (as a group) from typical feedstocks containing REEs and / or PGMs; and (ii) Separation and purification of the REEs and / or PGMs individually (or respectively) from each other. [Background technology]

[0004] (background) Rare earth elements (hereinafter referred to as REE) include the following (i) and (ii). (i) The 15 elements with atomic numbers 57 to 71 in the periodic table of the elements, consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); (ii) Scandium (atomic number: 21) and yttrium (atomic number: 39) Therefore, the total number of REEs is 17. However, of these 17 Rare Earth Elements (RRE), only 16 are of general interest because only one, promethium (Pm), is a radioactive isotope. REEs share many similar characteristics (or properties) and occur together in geological deposits. Based on their properties, REEs are broadly divided into two groups: (1) and (2). (1) Light REE (La~Gd) and (2) Heavy REE (Tb~Lu) Yttrium is one of the lightest REEs, but is grouped with the heavy REEs because its physicochemical properties are similar to the heavier REEs.

[0005] In nature, the REEs are found in a number of inorganic substances, typically as halides, carbonates, oxides, phosphates and silicates. However, the most important sources of REEs are the minerals bastnaesite, monazite and xenotime. Typically, these minerals (or inorganic substances or minerals) contain a few percent by weight of REEs.

[0006] The platinum group metals (PGMs), also known as precious and noble metals, are rare, naturally occurring, metallic chemical elements consisting of six elements: ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt). The term "precious" refers to its high price and economic value, while the term "noble" refers to its chemical inertness. PGMs are characterized by distinct physical and chemical properties that distinguish them from other base metals (e.g., iron, cobalt, nickel and copper) that exist in the same group (or group) of the periodic system of elements.

[0007] PGMs are extremely rare compared to many of the less abundant elements such as the REEs. PGMs are predominantly chalcophillic (i.e., sulfur-loving or sulfur-loving) and are therefore found primarily in sulfidic minerals. Some of the PGMs also exist as minerals (or inorganic substances or minerals) (e.g., chromite, telluride, selenide, arsenide, and antimonide). The primary sources of PGMs are natural ores, but scrap or waste materials or secondary materials are also important sources. In particular, discarded electronic scrap, used automotive catalytic converters, used batteries, used electric lamps, super alloys, jewellery scrap and industrial waste (e.g. plating solutions and plating sludge) are listed as potential sources of PGMs.

[0008] REEs and PGMs are groups of metals that play important roles in our modern world. They are key components of many emerging high technology, new energy and defense industries because of their unique nuclear, metallurgical, chemical, catalytic, electrical, magnetic and even optical properties.

[0009] The applications of REEs and PGMs depend not only on their characteristics but also on their purity. Their market price therefore increases significantly depending on their purity. Sources of REEs and / or PGMs are inorganic and secondary materials, which consist of mixtures of several REEs and / or PGMs. Therefore, for use in high-tech applications, they need to be separated from their respective matrix components and also from each other with a high degree of purity. However, similar physicochemical properties make separation of REEs and / or PGMs difficult, posing a formidable industrial challenge.

[0010] The production of commercial products of each REE or each PGM begins with a mining process, in which the respective ore material is removed from the earth, crushed and ground to a suitable particle size. This is then further processed with the aim of isolating the minerals (or minerals) containing the REEs and / or PGMs. The treatment processes (or processing steps) are intended to concentrate (or enrich) the REEs and / or PGMs in inorganic (or minerals) and typically include flotation and magnetic separation. Concentrates of inorganic matter (or minerals) containing REEs and / or PGMs of fairly high purity can be produced by this approach.

[0011] Each ore concentrate is then further refined to yield a concentrate of REEs and / or PGMs. This is done by dissolving the rock material in a suitable mineral acid (e.g., hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), aqua regia (3HCl + 1HNO3)) or a strong base (e.g., caustic soda (NaOH) or caustic potash (KOH)). Dissolution often requires treatment at elevated temperatures. The resulting salts of the REEs and / or PGMs, typically chlorides, sulfates and nitrates, or hydroxides of the REEs and / or PGMs, are then separated into the single elements. The difficult process is due to the similar physicochemical properties of the REEs and / or PGMs.

[0012] Solvent extraction is the most common separation method. In solvent extraction, an organic solvent (containing a complexing agent (e.g., extractant)) is made to flow countercurrently to a water stream (containing the incoming salts of the mixed REEs and / or PGMs). Complexes are formed between (REE and / or PGM ions) and (extractant molecules) and the REEs and / or PGMs are separated based on the difference in the stability constants (or coefficients or constants) of the various REE and / or PGM complexes.

[0013] This presents a significant disadvantage to the process, since solvent extraction requires hundreds or even thousands of extraction steps to achieve sufficient separation and sufficient purity. Furthermore, each plant must be custom built (or made to order) for the particular feedstock and the particular purity of the products being separated. Solvent extraction consumes large amounts of process chemicals and has associated Health, Safety and Environment (HSE) challenges.

[0014] Ion exchange chromatography (Ion Exchange Chromatography) or Ligand-Assisted Displacement Chromatography (LGA) is an alternative process. It was widely used, but was later replaced by the solvent extraction process in the 1970s. Typically, polyvinylsulfonyl acid was used as a strong cation exchange material for the REEs, and quaternary ammonium salts were used as strong anion exchangers for the PGMs. After loading, the REE or PGM ions are exchanged with suitable ions in the presence of a ligand. Such mixtures must be passed through several columns to achieve high purity, require large volumes of ligand solution, and require extremely long exchange times (up to weeks) to separate a few grams of REE or PGM, resulting in low productivity. In addition, after each run, the column must be regenerated with an appropriate solution. This leads to a more significant increase in production costs (in the range of $40 / kg), making it uneconomical and therefore unsuitable for large-scale manufacturing (or production or production).

[0015] Recently, a process of ligand-assisted elution chromatography (or ligand-assisted elution chromatography or ligand-assisted elution chromatography) for separating metal ions, especially rare earth elements (REEs), has been published (Wang et al., 2020, U.S. Patent No. 10,597,751 B2). The method is based on a two-set column system and uses two sets of eluting ligand solutions in combination. The first set of columns contains a strong acid cation exchange resin. The second set of chromatographic columns contains polyvalent metal oxides (hydrous) (eg, TiO2, ZrO2, or SnO2) and the eluting ligand is a solution of EDTA and / or DTPA. The proposed method claims to produce substantially pure rare earth elements with reasonably high productivity and relatively low production costs in both batch and continuous chromatography modes, and is therefore suitable for large-scale production.

[0016] However, the proposed process is relatively complex, utilizing two sets of column systems and multiple solvents for washing, elution and regeneration, some of which are very expensive chemicals. Moreover, this method requires a longer cycle time (more than 12 hours). In fact, this cycle time is significantly shorter than that of ligand-assisted displacement chromatography (i.e., about 3 weeks). However, the cycle time is still much longer. Furthermore, according to the data in this literature, the claimed lower production costs (3.4-8.9$ / kg) are highly dependent on and sensitive to the amount of elution ligand (or elution ligand or elution ligand) that is recycled (or reused). Furthermore, according to the data in this literature, even a small decrease (e.g., from 99% to 95%) in the proportion (or percentage or %) of the eluted ligand recycled would result in an increase in production costs of more than about 265%. Such an increase is significantly large and risky. Moreover, the use of solutions of organic compounds in this process inevitably produces environmentally unfriendly waste products which must be disposed of.

[0017] Extraction chromatography is another method used to achieve separation of REEs, originally developed in the 1960s with the advent of solvent extraction. In extraction chromatography, the separation column is impregnated with a chelating agent (often used in solvent extraction) to increase the selectivity of the adsorbent for the REEs or PGMs.

[0018] A major limitation of extraction chromatography is its inherently low capacity, which is due to the small amount of extractant present in the extraction column, which in turn results in low productivity and extremely high resin costs (over 16,000 / Kg). As a result, the method has not been developed at all, even to industrial scale, and is limited to analytical chromatography only.

[0019] The mining and enrichment of REE and PGM containing minerals can be found, inter alia, at www.mineralsUK.com and summarized in the book Nature's building blocks an A - Z guide to the elements, John Emsley, Oxford University press, ISBN 0-19-8500340-7. Summary of the Invention [Problem to be solved by the invention]

[0020] Existing REE and PGM separation and purification methods are technically inadequate, have adverse environmental effects, are characterized by complex and lengthy processes, are therefore not suitable for large-scale production and / or require large investments and manufacturing costs. As new technologies emerge and grow that rely on the unique properties of REEs and PGMs, there is an increasing demand for high purity individual REEs and PGMs from high technology and defense industries around the world. There is also overwhelming pressure, both internationally and domestically, to reduce the pollution levels caused by current REE and PGM separation and purification techniques. There is a need for innovative, efficient, cost-effective and environmentally friendly methods and systems for separating REEs and PGMs.

[0021] Currently, attempts have been made to improve upon the inherent limitations of extraction chromatography (i.e., the low capacity of the extraction column) to enable preparative applications. Various kinds (or types) of reverse phase silica materials are employed and the extractant (or extractant) is physically impregnated using various impregnation techniques.

[0022] Wide pore (>300 Å) reverse phase (RP) silica exhibited better extractant retention capacity (~183%) than narrow pore (100 Å) RP-silica, despite having less than half the surface area. In other words, previous studies have supported the use of wide-pore silica with pore sizes larger than 300 Å for extraction chromatography and rejected the use of narrow-pore RP-silica with pore sizes smaller than 300 Å.

[0023] The main reason for the low retention capacity or reactant density of narrow pore RP-silica was related to the low diffusion of extractants due to their viscous nature, which hindered the access of extractant molecules to all available binding sites of narrow pore RP-silica. The use of organic solvents (e.g., diluents) has not been useful because the organic solvent flushes the extractant, resulting in an even lower extractant density. In other words, narrow pore RP-silica was found to provide a lower than desired density of extractant compared to wide pore RP-silica (having pore sizes larger than 300 Å).

[0024] The general object of the present invention is to develop an alternative methodology and industrial process for separation of REEs and PGMs, respectively, from commercially available sources of mixed REE concentrates or PGM concentrates (i.e., an alternative to the above methods which is more environmentally friendly and cost effective) and which avoids or substantially reduces the technical, environmental and other problems associated with the prior art technologies.

[0025] One specific object of the present invention was to develop a stationary phase having substantially increased capacity (i.e. extractant density) for the separation and purification of REEs and / or PGMs by extraction chromatography and solid phase extraction.

[0026] Other objects will become apparent to those skilled in the art upon reading this specification. [Means for solving the problem]

[0027] Summary of the Invention In a particular embodiment, the present invention relates to a stationary phase for the chromatographic separation and / or purification of REEs and / or PGMs. The stationary phase comprises an extractant, the extractant being immobilized on a support; The support comprises a reverse phase silica particle (or reverse phase silica particle or reverse phase silica particle), which is characterized by an average pore size (or average pore (or pore or pore) size (or dimension or size) or average pore diameter or average pore size) of less than 2,000 Å. The extractant comprises an organic compound having complex-forming properties capable of retaining and separating the REEs and / or PGMs by forming complexes with various REEs and / or PGMs ions, the complexes having various stability constants. The extractant is impregnated into the support at a temperature in the range of 35° C. to 80° C., for example 70° C., and / or in an ultrasonic treatment step.

[0028] In some embodiments, the reverse phase silica particles have an average pore size of less than 300 Å and a pore size of less than 170 nm. 2 / g.

[0029] In some embodiments, the reverse phase silica particles have an average pore size in the range of 50 Å to 150 Å, for example, an average pore size of 60 Å and a pore size of 200 to 600 nm. 2 Surface area in the range of 560 m / g, e.g. 2 It is characterized (or characterised) by its surface area per g.

[0030] In some embodiments, the temperature is in the range of 50°C to 60°C.

[0031] In some embodiments, the extractant comprises an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or a combination thereof.

[0032] In some embodiments, the extractant comprises an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or a combination thereof, and has the general formula: [ka] [In the formula, R 1 and R 2 is independently a lipophilic (or lipophilic) hydrocarbon or modified hydrocarbon, said hydrocarbon being selected from the group including C6-20 alkyl, C6-20 aryl; R 3 is H, C1-C6 alkyl and C1-C6 aryl.

[0033] In some embodiments, the extractant comprises di-(2-ethylhexyl)phosphoric acid (DHEHP), di-(2,4,4-trimethylpentyl)phosphinic acid (H[TMPeP]) and 2-ethylhexyl, 2-ethylhexylphosphonic acid (H[(EH)EHP]), aliquat-336 [N(CH3)4], dioctyl sulfide [S(CH2)2], or a combination thereof.

[0034] In a particular embodiment, the present invention relates to an extraction column for chromatographic separation and / or purification of REEs and / or PGMs, the extraction column comprising a stationary phase as described in this disclosure.

[0035] In a particular aspect, the present invention relates to a method for producing (or preparing or providing or preparing or forming) a stationary phase for the chromatographic separation and / or purification of REEs and / or PGMs. The method comprises the following steps (i) and (ii). (i) providing a support, the support comprising reverse phase silica particles, the reverse phase silica particles being characterized by an average pore size of less than 2,000 Å; (ii) Impregnating the reversed phase silica particles of step (i) with at least one extractant, At least one extractant is an organic compound, the organic compound having complex-forming properties capable of retaining and separating the REEs and / or PGMs, such complex-forming properties being due to the formation of complexes with ions of various REEs and / or PGMs, the complexes having various stability constants (or coefficients or constants), the process. The extractant is impregnated into the support, and the impregnation conditions are the following two conditions: Temperature within the range of 50°C to 80°C, for example, 70°C, Sonication process (or Ultrasonic Treatment step) At least one of the following conditions is met: In some embodiments, the temperature is in the range of 50°C to 60°C.

[0036] In some embodiments, the reverse phase silica particles have an average pore size (or average pore (or pore or pore) size (or dimension or size) or average pore diameter or average pore size) of less than 300 Å and a mean pore size (or average pore diameter or average pore size) of less than 170 nm. 2 / g.

[0037] In some embodiments, the reverse phase silica particles have an average pore size in the range of 50 Å to 150 Å, for example, an average pore size of 60 Å and a pore size of 200 to 600 nm. 2 Surface area in the range of 560 m / g, e.g. 2 It is characterized (or characterised) by its surface area per g.

[0038] In some embodiments, the extractant comprises an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or a combination thereof.

[0039] In some embodiments, the extractant comprises an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or a combination thereof, and has the general formula: [ka] [In the formula, R 1 and R 2 is independently a lipophilic (or lipophilic) hydrocarbon or modified hydrocarbon, said hydrocarbon being selected from the group including C6-20 alkyl, C6-20 aryl; R 3 is H, C1-C6 alkyl and C1-C6 aryl.

[0040] In some embodiments, the extractant comprises di-(2-ethylhexyl)phosphoric acid (DHEHP), di-(2,4,4-trimethylpentyl)phosphinic acid (H[TMPeP]) and 2-ethylhexyl, 2-ethylhexylphosphonic acid (H[(EH)EHP]), aliquat-336 [N(CH3)4], dioctyl sulfide [S(CH2)2], or combinations thereof.

[0041] In a particular embodiment, the present invention relates to a method for separating and / or purifying REEs and / or PGMs from an aqueous solution containing REEs and / or PGMs. The method includes the following steps (or steps) (a) to (d): (a) Providing an extraction column according to the present disclosure; (b) loading an aqueous solution containing REEs and / or PGMs onto an extraction column; (c) using an eluent mode to separate the REEs and / or PGMs; and (d) A step (or steps) of eluting the separated REEs and / or PGMs from the extraction column.

[0042] In some embodiments, the eluent mode is an eluent concentration mode and / or an eluent flow rate gradient mode. Then, as appropriate, the eluting step is performed by: (i), (ii) or (iii) below. (i) isocratic concentration of the eluent mineral acid in aqueous solution, (ii) the linear gradient concentration of the eluent mineral acid in aqueous solution, or (iii) The step-wise gradient concentration of an eluent mineral acid in an aqueous solution.

[0043] In some embodiments, the method further comprises at least one of the following steps (or steps) (e)-(g). (e) collecting the fraction of the eluate (or eluate) containing the REEs and / or PGMs; (f) final concentration (or final concentration or up-concentration or up-concentration) of the eluted REE and / or PGM fraction (up-concentrating); and (g) A process for recovering mineral acid and water from the eluent.

[0044] In some embodiments of the method, the elution and collection of fractions in steps (d) and (e) are controlled in a manner to recover REEs and / or PGMs (that have similar retention capacities in a given extraction column) from one or more extraction columns.

[0045] In some embodiments, the solution of REEs and / or PGMs that is loaded onto the column comprises an acid matrix, which allows the REEs and / or PGMs to be quantitatively retained by a given column.

[0046] In some embodiments, the quantitatively retained REEs and / or PGMs are REEs and are eluted with an eluent whereby the acid concentration and / or eluent flow rate are increased to elute first the light REE group, then the SEG-REE group, and then the heavy REE+Y group.

[0047] As contemplated in the present disclosure, in some embodiments of the method, (i) The light REE group is either absent or contains at least one of La, Pr and Nd; (ii) the SEG-REE group is absent or contains at least one of Sm, Eu and Gd; (iii) the heavy REE+Y group is absent or contains at least one of Tb, Dy, Ho, Er, Tm, Yb, Lu and Y; At least one of the three groups (i), (ii) and (iii) is present.

[0048] In some embodiments, the REEs and / or PGMs include PGMs, which are quantitatively retained and eluted with an eluent by increasing the concentration of an acid and / or the flow rate of the eluent. (i) a first group of PGMs (or primary group PGMs) is eluted first, the first group of PGMs including at least one of Pd and Pt; (ii) A second group of PGMs (or secondary group PGMs) is eluted second, and the second group of PGMs includes at least one of Rh, Ru, and Ir.

[0049] In some embodiments of the method, the elution and collection of the fractions in steps (d) and / or (e) is controlled to recover substantially pure fractions of each metal derived from the REEs and / or PGMs.

[0050] In some embodiments, fractions containing the REE group, individual REEs, PGM groups or PGMs are recovered and concentrated by distillation, ion exchange, membrane filtration, centrifugation, solvent extraction, evaporation, azeotropic distillation, liquid-liquid extraction, or a combination thereof to recover an eluate.

[0051] In some embodiments, one or more of the concentrated fractions are converted to an insoluble salt or oxide of the metal, respectively, which are recovered and dried.

[0052] In some embodiments, the elution is carried out under a pressure of 50-100 bar.

[0053] In some embodiments, the aqueous solution is acidic.

[0054] In some embodiments, the quantitatively retained REEs are eluted using an eluent which increases the acid concentration and / or eluent flow rate to first elute the light REE group, then the SEG-REE group, and then the heavy REE+Y group. The light REE group mainly contains La, Pr and Nd. The SEG-REE group includes Sm, Eu and Gd. The heavy REE+Y group mainly contains Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.

[0055] In some embodiments, the quantitatively retained PGMs are eluted using an eluent that increases the acid concentration and / or eluent flow rate to first elute the first group of PGMs (or primary group PGMs) and then the second group of PGMs (or secondary group PGMs). The first group of PGMs includes Pd and Pt. The second group of PGMs includes Rh, Ru and Ir.

[0056] In some embodiments, the elution and collection of the fractions is controlled to recover substantially pure fractions of each REE or PGM.

[0057] In a particular embodiment, the present invention relates to a method for industrial separation and purification of each REE and / or PGM from an aqueous mixture of REE and / or PGM. In the method, from an incoming solution containing mixed REEs and / or PGMs, (i) First, the REEs and / or PGMs are separated into subgroups of REEs and PGMs by the methods described herein, and then (ii) One or more of the subgroups of REEs and / or PGMs are isolated (or separated) as described in this disclosure. [Brief description of the drawings]

[0058] Core Invention [Figure 1]Figure 1 shows a Pareto chart of standardized effects, which is a plot of the significance of experimental variables. Factors that are above the reference line of 2.31 have a significant effect on the response. The degree of influence is proportional to the length of each bar. [Diagram 2] Figure 2 shows response surfaces derived from factorial design, showing the effect of (a) pore size and ultrasound, (b) pore size and temperature, and (c) temperature and ultrasound on the density of the stationary phase extractant. [Diagram 3] FIG. 3 shows the immobilization of organophosphorus compounds (as model extractants) onto porous RP-silica particles (present invention). [Figure 4] FIG. 4 is a simplified diagram showing a method for packing an extraction column in accordance with the present invention. [Diagram 5] FIG. 5 is a simplified flow diagram showing a process according to the present invention. (Lab-scale test) [Figure 6] Figure 6 shows the elution profiles of lighter REEs obtained after elution with various mineral acids under the same conditions using extraction chromatography. [Figure 7]Figure 7 shows the retention times (Rt) of REEs obtained after elution with various mineral acids under the same conditions using extraction chromatography. [Figure 8] Figure 8 shows the resolution (Rs) of REEs after elution with various acids under the same conditions using extraction chromatography. [Figure 9] Figure 9 shows the elution profiles of REEs obtained using extraction columns containing various densities of ligands under the same chromatographic conditions. [Figure 10] Figure 10 shows the REE peak width (w) as a function of the eluent flow rate (u). [Figure 11] Figure 11 shows the resolution (Rs) between adjacent REEs as a function of the eluent flow rate (u). [Figure 12] FIG. 12 shows the REE peak width (w) as a function of temperature (T). [Figure 13] FIG. 13 shows the resolving power (Rs) of REEs as a function of temperature (T). [Figure 14] FIG. 14 is a chromatogram showing the REE peak shape at high REE loading. [Figure 15] FIG. 15 shows the separation of PGMs (as a group from those with base metals) using an Aliquat-336 extraction column. [Figure 16]FIG. 16 shows the separation of Pd from other PGMs using a di-octyl sulfide (DOS) extraction column. [Figure 17] FIG. 17 shows the separation of Rh from other PGMs using a di-ethyl tri-amine (DETA) extraction column. (Pilot scale test) [Figure 18] Figure 18 is a chromatogram showing group separation of REEs derived from pilot-scale testing using extraction chromatography. [Figure 19] Figure 19 is a chromatogram showing the individual separation of the lighter REEs from pilot-scale testing using extraction chromatography. [Figure 20] FIG. 20 is a chromatogram showing the individual separations of SEG-REEs derived from pilot-scale testing using extraction chromatography. [Figure 21] Figure 21 is a chromatogram showing the individual separation of heavy REEs from pilot-scale testing using extraction chromatography. [Figure 22] FIG. 22 is a chromatogram showing the individual separation of heavy REE+Y from pilot scale testing using extraction chromatography. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] (Detailed description of the first aspect of the present invention) In the context of this specification, all publications, patent applications, patents, and other documents mentioned herein are expressly incorporated by reference in their entirety into this disclosure for all purposes, as if fully set forth, unless otherwise stated.

[0060] Unless otherwise defined (or defined), all technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of conflict, the present specification, including definitions, will control.

[0061] Unless expressly stated otherwise, trademarks are shown in capital letters.

[0062] Unless otherwise stated, all percentages, parts, ratios, etc. are by weight.

[0063] Unless otherwise stated, pressures expressed in psi are gauge pressures and pressures expressed in kPa are absolute pressures. However, the pressure differences are expressed as absolute pressures (eg, pressure 1 is 25 psi higher than pressure 2).

[0064] When an amount, concentration, or other value or parameter is described as a range or as a list of upper and lower limits, this is to be understood as specifically disclosing all ranges formed from any combination (or pair or set) of any upper range and any lower range, notwithstanding that the ranges are individually disclosed. In this disclosure, where a range of numerical values ​​is set forth, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions (or fractions or fractions) within the range. When a range is specified, it is not intended that the scope of the disclosure be limited to the specifically recited values.

[0065] When the term "about" is used, it is used in the sense that a certain effect or result can be obtained within a certain acceptable range, and that one of ordinary skill in the art knows how to obtain that acceptable range. When the term "about" is used in describing a value or an endpoint (or end point) of a range, the disclosure should be understood to include the specific value or endpoint (or end point) described.

[0066] As used in this disclosure, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a reference to a process, method, article, or apparatus (including a listing of components) is not necessarily limited to only the recited components. Such process, method, article, or apparatus may include other components not expressly listed or other components not inherent to such process, method, article, or apparatus.

[0067] The transitional phrase "consisting of" excludes any component, step, or ingredient not specifically recited in the claim and closes the claim to include materials other than those recited (but including impurities which ordinarily accompany them). When the transitional phrase "consisting of" appears in the body of a claim (but not immediately following the preamble), it only limits the components (or ingredients or elements) recited in that portion of the claim and does not exclude other components (or ingredients or elements) from the claim as a whole.

[0068] The transitional phrase "consisting essentially of" limits the scope of the claim to those things (or substances or materials) or processes (or steps) specifically recited and that do not materially affect the basic and novel feature(s) of the claimed invention. A claim "consisting essentially of" occupies a middle ground between a closed claim written in the "consisting of" format and a fully open claim written in the "comprising" format. Optional additives (at appropriate levels for such additives) and minor amounts of impurities as defined (or specified) in this disclosure are not excluded from a composition (or composition or composition) by the term "consisting essentially of."

[0069] Further, unless expressly stated to the contrary, "or" and "and / or" are intended to be inclusive and non-exclusive. For example, condition A or B, or A and / or B, is satisfied by any one of the following: A is correct (or A exists) and B is wrong (or B does not exist), A is wrong (or A does not exist) and B is right (or B exists), Both A and B are correct (or both A and B exist).

[0070] "A" or "an" are used to describe various elements and components of the present disclosure and are used merely for convenience and to give a general sense of the present disclosure. Unless otherwise clearly indicated, the terms one or at least one and singular should be construed as including the plural cases within this disclosure.

[0071] (definition) "Rare Earth Elements" means the set of 17 metallic elements. The 17 metallic elements include the following: (i) The 15 lanthanide group (elements with atomic numbers 57-71 in the periodic table of the elements), namely lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and ruthenium (Lu), as well as (ii) Scandium (atomic number 21) and yttrium (atomic number 39)

[0072] "Platinum Group Metals" means the six noble or precious metallic elements, namely, platinum, palladium, rhodium, ruthenium, iridium and osmium.

[0073] "Pore Size" means the mean or average pore size of a pore in a support material that is used to prepare (or prepare or prepare or form) a stationary phase.

[0074] "Reversed-Phase Silica" means a stationary phase used in liquid chromatography that has long carbon chains attached to silica particles that have no dominant polar character.

[0075] "Extractant Density" means the amount of extractant retained by 1 gram of solid support (in this case, reversed phase silica particles).

[0076] Reverse-phase silica particles are commercially available from a variety of suppliers and are commonly used as stationary phases in chromatography. They are produced by modifying silica particles with polar surfaces (e.g., by attaching alkyl groups to the surface of the silica particles). [ka]

[0077] R is typically an alkyl chain, such alkyl chain having 4, 8 or 18 C atoms.

[0078] Silica particles modified in this manner are widely (or commonly) used for the chromatographic separation of compounds having various affinities for the surface of the non-polar particles modified in this manner. The silica particles thus modified may also be used for immobilization (or immobilization) of ligands (or ligands) (with non-polar ends) by van der Waals bonds to the thus modified particles.

[0079] According to the present invention, the capacity of an extraction column (i.e., the amount of material purified in one chromatographic cycle) increases with increasing amount of extractant contained in the extraction column. The latter may be described as the extractant density (i.e., the amount of extractant retained by 1 g of solid support, in this case reversed phase silica particles).

[0080] Due to their hydrophilic or lipophilic nature, the original (or native) silica particles do not retain the extractants, which are generally hydrophobic. The polar surface of the original (or native) silica material can be modified to become hydrophobic by attaching a hydrocarbon (R) to the surface, where R is typically an alkyl chain, such alkyl chains having 4, 8 or 18 C atoms (see below). Native silica is also known as normal phase (NP) silica, whereas the above materials are called reverse phase (RP) silica, named after their non-polar surface.

[0081] In one embodiment, the present invention relates to the separation and purification of REEs and / or PGMs using extraction chromatography. A chromatography column is manufactured (or prepared or ready or formed) by packing (or loading or loading) with a stationary phase (or stationary phase), which is reverse phase silica (or reverse phase silica). The RP-silica of the present invention contains an extractant, which is impregnated and immobilized on its porous surface. Impregnation is carried out under two prominent driving forces: high temperature and ultrasonic treatment. As a result, the concentration of extractant in RP-silica is significantly higher, which correlates directly with the separation efficiency of REEs and / or PGMs. A first source (or source or source) (or primary source) and a second source (or source or source) (or secondary source) of REEs and / or PGMs can be treated by the columns and processes of the present invention.

[0082] Depending on the specific use (or application), currently preferred extractants (or extractants) are dialkyl phosphoric acids, such as di-(2-ethylhexyl) phosphoric acid (DHEHP); di-(2,4,4-trimethylphenyl) phosphonic acid (H[TMPeP]); and 2-ethylhexyl 2-ethylhexylphosphonic acid (H[(EH)EHP]); aliquat-336 [N(CH3)4]; dioctyl sulfide [S(CH2)2]; and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0083] In one embodiment, the extractant comprises one or more of di-(2-ethylhexyl)phosphoric acid (in dilute H2SO4 / HCl / HNO3), 2-ethylhexyl 2-ethylhexylphosphonic acid, tributyl phosphate, di(2-ethylhexyl)phosphoric acid (DEHPA), 2-ethyl-hexyl-2-ethyl-hexyl-phosphoric acid, tri-butyl phosphate, peracetic acid and / or peracetic acid 10.

[0084] In one embodiment, the extractant is one or more of bis(2,4,4-trimethylphenyl)phosphinic acid, bis(2-ethylhexyl)phosphinic acid, bis(2-ethylhexyl)phosphonic acid, phenylphosphonic acid, 2-ethylhexylphosphonic acid, mono-2-ethylhexyl ester, and / or salts thereof.

[0085] In another embodiment, the extractant (or extractant) is one or more of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester trialkylmethylammonium or di-2-ethylhexyl phosphate trialkylmethylammonium, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester trialkylmethylammonium ([A336][P507]), di-2-ethylhexyl phosphate, trialkylmethylammonium ([A336][P204]) and / or quaternary ammonium ionic liquid extractants cations and anions (i.e., 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester trialkylmethylammonium and di-2-ethylhexyl phosphate trialkylmethylammonium).

[0086] In one embodiment, the extractant (or extractant) is one or more of di-(2-ethylhexyl)phosphoric acid (HDEHP), mono(2-ethylhexyl) 2-ethylhexylphosphonate (HEH / EHP), bis(2,4,4-trimethylpentyl) monothiophosphinic acid), octylphenyl phosphate (OPAP), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A) and optionally toluene, tributyl phosphate, di-isoamyl methylphosphonate, 7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline, di-(2-ethylhexyl)phosphinic acid, bis(2,4,4-trimethylpentyl)phosphinic acid, 8-hydroxyquinoline, (2-ethylhexyl)phosphonic acid, and / or mixtures thereof.

[0087] Such extractant solvents are described in U.S. Pat. No. 9,752,212 and U.S. Patent Publication No. 2015 / 0104361, which are incorporated by reference in their entireties in this disclosure.

[0088] Reversed Phase (RP) silica particles are commercially available from a variety of suppliers and are commonly used by the pharmaceutical industry as the stationary phase in reversed phase liquid chromatography.

[0089] In the context of the present invention, the average pore (or pore or pore) size (or dimension or size) (or average pore size) of the reversed-phase silica particles that can be used is in the range of about 50 Å (angstroms) to about 2000 Å (angstroms). In one embodiment, the average pore size (or average pore (or pore) size (or dimension or size)) is any number selected from the following numbers, or a number within a range defined by any two of the following numbers (including the end points of such ranges) (measured in Å (Angstroms)): 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900 and 2000.

[0090] In the context of the present invention, the surface area of ​​the reverse phase silica particles that can be used is about 20 m 2 / g~about 600m 2 / g. In one embodiment, the surface area is any number selected from the following numbers, or a number within a range defined by any two of the following numbers, including the end points of such ranges: (m 2 (measured in g / g).

[0091] 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590 and 600.

[0092] In a preferred embodiment, the surface area is approximately 170 m 2 / g ~ approx. 560m 2 / g.

[0093] In the present invention, the impregnation of the extractant into reversed-phase silica is carried out under ultrasonic treatment. In one embodiment, elevated temperature is combined with ultrasonic treatment for impregnation. Sonication may be continuous or intermittent. It may also be periodic or random. Ultrasonic power output (or power output) is in the range of 0-100%. In other words, the power output can be any number from those listed below, including any number within a range defined by any two of the following numbers, including the ends (or endpoints) of such range (measured in %):

[0094] 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100.

[0095] In a preferred embodiment, the power output is in the range of 40-50%.

[0096] In one embodiment, the temperature of the impregnation is in the range of ambient temperature to 80°C. In another embodiment, the temperature is any number from the list below, including any number within a range defined (or defined) by any two of the following numbers, including the ends (or endpoints) of such range (measured in °C):

[0097] 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 and 80.

[0098] In a preferred embodiment, the temperature range is from about 50°C to about 60°C.

[0099] In one embodiment, sonication (or ultrasonic treatment) is used for impregnation of the extractant.

[0100] In another embodiment, the ultrasonic frequency range used is in the range of 20 kHz to about 100 kHz, working best in the range of 40 kHz to 60 kHz.

[0101] In one embodiment, the ultrasonic frequency ranges from 20 kHz to 100 kHz. In other words, the frequency of the ultrasound is any number from those listed below, including any number within a range defined by any two of the following numbers, including the ends (or endpoints) of such range (measured in kHz):

[0102] 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100.

[0103] In extraction chromatography (ExC), organic compounds with complex-forming properties (extractants) are immobilized on an inert solid support (inert solid support) and used as the stationary phase. Equation 1 (Eq-1) shows the general equation responsible for the separation of REEs by ExC using an extractant (denoted as HLn) (as the stationary phase) and a mineral acid (as the eluent).

[0104]

number

[0105] The extractant is considered to be a molecule that can be mono-ionized, with three molecules bonded to one REE cation, breaking the hydrogen bond through the oxygen atom that it was previously bonded to by the proton being exchanged.

[0106] The equilibrium constant (K) of Eq-1 is written as Equation-2 (Eq-2), where K is the stability constant (also known as the stability constant) of the metal-extractant complex. K = [RE(Ln)3] org *[H + ] 3 aq / [RE 3+ ] aq *[HLn] 3 org (Eq-2)

[0107] The distribution ratio (D) is a measure of the distribution of a solute in two immiscible solvents and can be calculated by dividing the total concentration of the metal ion extracted into the organic phase by the total concentration in the aqueous phase. In column extraction chromatography, the partition ratio (D) is similar to the ratio of the molar concentration of metal ions in the stationary phase (i.e., the extractant impregnated on the support) to the molar concentration of metal ions in the mobile phase (the acid of the eluent). D = [RE(Ln)3] org / [RE 3+ ] aq (Eq-3)

[0108] Dividing Eq-3 by Eq-2 and rearranging again gives Eq-4. D=K*[HLn] 3 org / [H + ] 3 aq (Eq-4)

[0109] The distribution ratio (D) may also be mathematically related to certain column parameters, such as the retention volume (Vr) and the stationary phase capacity (Vs), as shown in Eq. 5. D=Vr / Vs (Eq-5)

[0110] Assuming that retention volume (Vr) = retention time (tR), combining Eq-5 with Eq-4 gives Eq-6. tR / Vs=K*[HLn] 3 org / [H + ] 3 aq (Eq-6)

[0111] If we take the logarithm of the equation and rearrange it, we get the following form: log tR=3log[HLn]-3log[H + ]+log Vs+K (Eq-7)

[0112] Equation 7 shows that the retention time (tR), also known as the capacity factor, has a direct third order dependence on the molarity of the extractant and a direct first order dependence on the capacity of the stationary phase (Vs). Eq-7 clearly shows that the more the amount of extractant in the column increases, the more the column capacity in terms of sample throughput or sample load increases, in other words, the more the production capacity increases.

[0113] The impregnation behavior of bulk RP-silica materials and pre-packed HPLC columns, based on batch and flow-through impregnation techniques, has been previously investigated using di-(2-ethylhexyl) phosphoric acid (HDEHP) and dioctyl sulfide (DOS), which are widely used as model extractants for the separation of REEs and extraction of PGMs, respectively.

[0114] From preliminary experiments, it has been known that the capacity of an extraction column (i.e. the density of the extractant in the RP-silica support) is strongly influenced by the diffusion of the extractant in the pores of the porous RP-silica particles as well as the nature of the RP-silica material (in particular its pore size and surface area).

[0115] The present invention is based on further experiments, whereby the effect of the pore size (surface area) of the RP-silica particles as well as the driving forces for enhancing the diffusion of the extractant (e.g. temperature and ultrasound on the capacity of the stationary phase (i.e. density of the extractant)) have been investigated.

[0116] (experiment) Extractants and bulk silica materials Di-(2-ethylhexyl)phosphoric acid (HDEHP) (99% purity) was obtained from ALFA AESAR® (Karlsruhe, Germany) and di-octyl sulfide (DOS) (99% purity) was purchased from Sigma Aldrich (Germany). Suprapur 65% HNO3 was purchased from MERCK® (Darmstadt, Germany). Single-element standard La solution (in HNO3 matrix) was obtained from Teknolab A / S (Kolbotn, Norway). Deionized water obtained from a MILLIPORE® Milli-Q system was used throughout. Bulk reverse phase silica materials, Luna 15 μm, C18-100; and Jupiter 15 μm, C18-300 (hereafter referred to as narrow pore and wide pore, respectively), were supplied by PHENOMENEX® (Torrance, CA, USA). The particle and bound phase specifications of the RP-Silica bulk material are shown in Table 1 below.

[0117] Table 1: Specifications of RP-silica and bare silica particles used in the experiment [Table 1]

[0118] (device) The HPLC system was an AGILENT® 1200 (USA) consisting of an autosampler, a four-pump solvent delivery system (or quaternary pump solvent delivery system) and an auxiliary isocratic pump (or auxiliary isocratic pump). A microwave plasma atomic emission spectrometer (MP-AES) (AGILENT®, USA) was connected to the HPLC system and used as a detector. For the ultrasonic reaction, a FISHER (registered trademark) Sonic Dismembrator Model 300 (Artek Systems Corporation, Farmingdale, NY, USA) was used.

[0119] (Software and data handling) Chemstation software (AGILENT® Technologies, USA) was used for instrument control, data acquisition and reporting. We used MINITAB®, a statistical software with 19 releases (MINITAB® Inc, USA, 2019), to construct the experimental design and perform statistical analyses.

[0120] Experimental variables and response parameters The capacity of an extraction column (i.e., the amount of material purified in one run) is directly related to the amount of extractant in the stationary phase used to prepare the extraction column. The amount of extractant in the stationary phase is then mainly influenced by the diffusion of the extractant into the pores of the RP-silica particles used as the support. Therefore, by improving the diffusion of the extractant into the pores of the RP-silica, the extractant density can be increased, thereby maximizing the capacity of the extraction column. Therefore, in the present invention, the size (or dimensions or sizes) of the pores (or pores or pores) of the RP-silica particles and the driving forces for diffusion, i.e., high temperature (or high temperature) and ultrasound (or ultra sound), were considered as experimental variables. It is also assumed that the capacity of the extraction column can be measured by the extractant density (i.e., the amount of extractant retained by 1 gram (g) of RP-silica support), and the extractant density is considered a response parameter that can be related to experimental variables.

[0121] Experimental Design Due to the large number of experimental variables considered, a multivariate approach using a two-stage factorial design (FD) is adopted to evaluate the effect of the experimental variables on the response parameter (i.e., extractant density). By using a multivariate approach (or multivariate analysis method or multivariate approach) in contrast to a univariate approach, it is possible to obtain combinations of variables (or variables), which provide the best response (or best response) with fewer experiments. Also, any interactions between experimental factors (or factors or coefficients) can be detected and estimated. A factorial design was constructed using Minitab-19 statistical software (testing experimental variables at two levels (upper and lower levels)). Upper and lower limits were set based on the results of preliminary experiments and on limitations imposed by the supplier of the RP-silica material used as the support. Eight experimental combinations x 2 (ie, a total of 16 runs) were performed.

[0122] (procedure) The study was carried out following the experimental design described above and the procedure described below using HDEHP as a model extractant. 2.2 g of small pore (narrow pore) or large pore (wide pore) RP-silica particles were accurately weighed and transferred into 100 mL round bottom flasks, each of which contained 50 mL of the extractant HDEHP and a magnetic stirrer. It should be noted that each set of reactions was a combination of 8 different runs, with each reaction run twice, for a total of 16 reactions.

[0123] The reaction setup (or apparatus) consisted of a hot plate on top of which was placed an ultrasonic water bath. The hot plate provided heat in a controlled manner as needed. The water bath maintained the temperature and served as the medium for ultrasound over the duration of the reaction time.

[0124] The driving forces examined were temperature and ultrasound. The lower limit of the temperature was room temperature (about 20°C) and the upper limit was set at 60°C. The upper limit was 10° C. below the maximum operating temperature (ie, 70° C.) that could be used with the RP-silica material according to specifications from the supplier. For ultrasound, the lower limit was 0% (i.e., no ultrasound). The upper limit was set at 50% (relative power (or output)). Ultrasonic frequencies higher than 50% (relative power output) were avoided so that the reverse phase silica material was not damaged. The flask was attached to a water-cooled condenser to cool the reaction vapor. The contents of the reaction flask were stirred at the slowest speed possible to maintain mixing while limiting damage to the silica surface. The reaction time was 2 hours in all cases. Each of the duplicate reactions was carried out in parallel. At the end of the reaction time, where applicable, heating, sonication and / or stirring was stopped and the reaction material was allowed to settle and cool to room temperature.

[0125] The above mentioned preparations of stationary phase (i.e., each containing precisely 2.2 g of stationary phase in approximately 50 mL of the extractant in question) were packed into sixteen 15 cm x 4.6 cm empty stainless steel column barrels using conventional high pressure slurry techniques. The extractants in question, HDEHP or DOS, were used as reaction solvents and also as packing solvents. After packing was complete, the column was flushed with water (flow rate = 5 mL / min for at least 2 h) to remove any loosely bound extractant from the column.

[0126] A control column was also packed, conventionally using high pressure, with a slurry containing exactly 2.2 grams (g) of RP-silica (in 50 mL of isopropanol) in an empty 15 cm x 4.6 cm stainless steel barrel (same dimensions as the test column). After loading, flush the column with copious amounts of water (flow rate: 5 mL / min) using the HPLC setup for flushing the isopropanol solvent. Such a control column was necessary to determine the void volume and to compare the retention behavior of the REEs in an unmodified RP-column with the retention behavior of the REEs in a column packed with a stationary phase manufactured according to the present invention.

[0127] (Results and Discussion) (Calculation (Determination of Capacity)) By online frontal chromatography using a HPLC setup (or instrument), La 3+ The capacity of an extraction column packed with a stationary phase manufactured according to the above procedure was estimated for adsorption of at least one REE ion retained with HDEHP (i.e., at least one REE ion retained with HDEHP). The test column was preconditioned with 0.01 M HNO3 (4 column volumes) before capacity determination. La solution (5 mM in 0.01 M HNO3) was pumped through the preconditioned test column at a constant flow rate of 1 mL / min until the metal broke through. The signal from the column effluent was continuously monitored, and the breakthrough curve was recorded by the MP-OES detector (emission line wavelength: 399.575 nm).

[0128] Determine the breakthrough volume (Vb) of the test extraction column by multiplying the flow rate (mL / min) and the respective breakthrough time (min) (see Equation 8 below). Vb(mL)=Tb(min)×u(mL / min) (Eq-8)

[0129] The void volume (Vo) of the extraction column was estimated using Equation 9. The void time (min) was obtained from the elution of La through the control column. 3 M HNO3 was used as the mobile phase. The flow rate was 1 mL / min. The concentration of the mobile phase (i.e., 3 M HNO3 solution) was strong enough to retain La ions on a control column packed with unmodified RP-silica. The dead volume was determined to be 1 mL and was used for all test columns. Vo (mL) = To (min) × u ​​(mL / min) (Eq-9)

[0130] The volume (or capacity) of the test extraction column (unit: La 3+ The meq of La was calculated using the corresponding breakthrough volume and void volume and the concentration of La (in the test solution) (as shown in Equation 10 (or Eq-10 or Equation-10)). Capacity of extraction column (meq) = [Vb-Vo] x Co x n (Eq-10) During the ceremony Vb is the breakthrough volume (mL) Vo is the void volume (mL) Co is La 3+ is the concentration (mmol / mL), n is La 3+ is the charge (or electric charge) of

[0131] (Statistical evaluation) The model matrix for a factorial design consisting of a set (×2) of experimental conditions is shown in Table 2 below. This model was fitted to the extractant densities obtained using Eq. 1 to Eq. 3 as the corresponding response values. The fitted model was used to generate a statistical response range to evaluate the effect of experimental variables (i.e., pore size of RP-silica, high temperature, and ultrasound) on the response (i.e., the density of the extractant used to measure the capacity of the stationary phase). A Pareto chart was created to assess the significance of the experimental variables on the response (Figure 1). The model also developed a response surface that was used to locate the condition of maximum adsorbent density in the tested domain (Figure 2).

[0132] Table 2: Model matrix of factorial design and corresponding response values. [Table 2]

[0133] As shown in the Pareto chart (Figure 1), all the experimental parameters studied (i.e., pore size, temperature and ultrasound) showed a significant influence on the extractant density of the stationary phase. However, as is evident from the length of each bar in the chart (or diagram), some parameters are more important than others, as explained below.

[0134] The present invention is also a process (or step or treatment or method) for impregnating an extractant using temperature and ultrasound (or ultrasonics). As evident from the response values ​​(i.e., extractant densities) in Table 2 and the surface plot in Figure 2, the highest extractant density (48.5 mmol / g) was achieved for narrow pore RP-silica, where both ultrasound and high temperature were applied as driving forces for impregnation. As a control, the lowest density of the extractant (5 mmol / g) was recorded, this time using narrow pore RP-silica, and no driving force was applied. The difference in density of the extractants observed using exactly the same support (narrow phase RP-silica) is large (i.e., about 750%), excluding the driving forces of impregnation (i.e., high temperature and ultrasound). Without wishing to be bound by theory, apparently the application of a driving force enhances the diffusion of the extractant into the narrow pores of the RP-silica over all or most of the available binding sites. This then results in a higher extractant density.

[0135] In other words, the present invention relates to reverse phase silicas with small or wide pores, blends of small + wide pore reverse phase silicas, distributions of reverse phase silicas (e.g., monomodal, bimodal or trimodal distributions of pore size of reverse phase silicas), where the impregnation of the extractant is performed at ambient to above ambient temperatures as well as under ultrasonic treatment (as described elsewhere in this disclosure as ultrasonic). In particular, stationary phases prepared as described in this disclosure exhibit several-fold and surprising improvements in the density of the extractant and therefore in the purification and / or separation of REEs and / or PGMs using extraction chromatography, as compared to the prior art. Such stationary phases can be used for laboratory to industrial scale separation and purification. In particular, even in the small pore (or narrow pore) range where impregnation of the extractant is problematic, the present invention solves such problems and shows a significant improvement in impregnation and density of the extractant.

[0136] Except for the pore size, the extractant density showed a direct correlation with the surface area of ​​the RP-silica under consideration when either or both driving forces were applied. Using exactly the same conditions (here, both high temperature and ultrasound, high temperature only, or ultrasound only were used as driving forces), the density of the extractant was found to be approximately twice as high for small pore (or narrow pore) RP-silica compared to large pore (or wide pore) RP-silica (Table 2). As shown in Table 1, the surface area of ​​small pore RP-silica is slightly more than twice that of large pore RP-silica.

[0137] On the other hand, in the absence of a driving force during the impregnation process, the extractant density was found to be significantly greater for large pore RP-silica (22 mmol / g) compared to that of small pore RP-silica (only 12 mmol / g), despite the surface area being less than half. The observed phenomenon could be attributed to the relatively good diffusion of the extractant into the larger pores of the large pore RP-silica, as opposed to the significantly smaller pores of the small pore RP-silica in the absence of a driving force.

[0138] Both of the driving forces investigated, namely ultrasound and high temperature, alone and in combination, appear to play an important role in promoting (or increasing or enhancing) the diffusion of the extractant (or extractant) in the pores of the RP-silica and thus substantially increasing the density of the extractant and, in turn, improving (or enhancing or increasing) the capacity of the extraction column. This effect is particularly large in the case of small pore (or narrow pore) RP-silica, the surface area of ​​which is more than twice as large as that of large pore (or wide pore) RP-silica. Regardless of the pore size of the RP-silica, when only one of the driving forces is employed, ultrasound gives slightly better results compared to high temperature. The impregnation conditions gave the highest extractant density in the following order:

[0139] Small pore RP-silica, high temperature, ultrasonic >>> Small pore RP-silica, ultrasonic >> Small pore RP-silica, high temperature >> Large pore RP-silica, ultrasonic, high temperature > Large pore RP-silica, ultrasonic > Large pore RP-silica, high temperature > Large pore RP-silica, no driving force > Small pore RP-silica, no driving force

[0140] In other words, the present invention provides a range of choices (or options) from which to choose for a desired extractant density.

[0141] In one embodiment, the extraction column comprises at least one of the following (1) to (7): (1) Small pore (or narrow pore) RP-silica (treated at high temperature and with ultrasound), (2) small pore (or narrow pore) RP-silica (treated with ultrasound), (3) small pore (or narrow pore) RP-silica (treated at high temperature), (4) Large pore (or wide pore) RP-silica (treated with ultrasound and high temperature), (5) Large pore (or wide pore) RP-silica (treated with ultrasound), (6) Large pore (or wide pore) RP-silica (treated at high temperature) and, if necessary, (7) A combination of two or more of the above.

[0142] In another embodiment, the invention described above further comprises: (a) and / or (b) below: (a) large pore (or wide pore) RP-silica (without impregnation driving force treatment), and / or (b) Narrow pore RP-silica (without impregnation driving force treatment)

[0143] Currently, as per the current state of the art, no driving force is applied during the impregnation process. As shown in Table 2 and discussed above, in the absence of a driving force during the impregnation process, wide pore RP-silica gives better extractant density (about 100% more) compared to narrow pore RP-silica, despite only having half the surface area. In both large pore (or wide pore) RP-silica and small pore (or narrow pore) RP-silica, the use of high temperature and ultrasound as impregnation driving forces according to the present invention resulted in a substantial improvement in the density of the extractant (large pore (or wide pore) RP-silica: about 227% and small pore (or narrow pore) RP-silica: about 750%). The improvement according to the present invention is approximately a 410% improvement over the highest extractant density achieved with current impregnation methods. The improvement in extractant density, and thereby the capacity of the extraction column, achieved according to the present invention, is large and could be a game changer by enabling extractive chromatography and solid phase extraction methods to compete with the successful solvent extraction currently used in industry for separation and purification of REEs and PGMs. To the best of the inventor's knowledge, this has never been attempted or reported before.

[0144] (summary) The inherent limitations of extraction chromatography are the low capacity of the stationary phase and the very high costs associated with the manufacture of extraction columns, which have limited its application for industrial-scale separation and purification of metal ions, despite its many attractive features (including simplicity, speed, and environmental friendliness).

[0145] The present invention substantially improves the capacity of stationary phases used in extraction chromatography and simplifies the methodology for preparing extraction columns, thereby eliminating limitations inherent in large scale methods for the preparation of metal ions, particularly REE and PGM ions.

[0146] The capacity of a stationary phase is measured by the amount of material that can be loaded and purified in one chromatographic run. The amount of material that can be loaded onto the stationary phase depends directly on the amount of extractant in the stationary phase, and more extractant means greater capacity

[15] . Therefore, the capacity of the stationary phase may be quantified by the amount of extractant present per gram (g) of stationary phase or the density of the extractant.

[0147] The effect on the density of the extractant of various parameters of RP-silica used as the solid support of the stationary phase as well as various conditions of the impregnation process adopted for immobilization of the extractant on the solid support have been studied, resulting in the present invention.

[0148] In one embodiment, results achieved according to the present invention result in an increase in the density of the extractant (i.e. the capacity of the stationary phase) of 400-700% (depending on the type of RP-silica used). The improvement in stationary phase capacity achieved in accordance with the present invention is significant, effectively eliminating the inherent limitations of extraction chromatography and the prohibitively high costs associated with the manufacture of extraction columns. Such results could also be a game changer in the large-scale production of REEs and PGMs by introducing extraction chromatography to the field as a green and cost-effective alternative to technically inadequate and / or environmentally unfriendly state-of-the-art solvent extraction and ion-exchange chromatography methods.

[0149] (Detailed description of the second aspect of the present invention) According to the present invention, the REEs and / or PGMs are separated by extraction chromatography. In extraction chromatography, an extraction column contains an organic compound (with complex-forming properties) (i.e., an extractant) physically impregnated into a solid support. Such a solid support is capable of retaining the REEs and / or PGMs by forming complexes with the REE ions or PGM ions, the complexes having different stability constants. Thus, the REEs and / or PGMs retained by the extraction column are eluted with a mineral acid as an eluent by increasing the acid concentration and / or the flow rate of the mobile phase.

[0150] In accordance with one embodiment of the present invention, an extraction column is prepared in a unique manner by physical impregnation of small pore or large surface area RP-silica particles with a suitable extractant. Figure 1 shows a schematic illustrating the mechanism of physical impregnation involving RP-silica (as a solid support) and DHEHP (as a model extractant).

[0151] A slurry (prepared for packing) of RP-silica and a suitable organic solvent is packed batchwise into an extraction column. The extractant is immobilized on the RP-silica (immobilization). The suitable organic solvent is preferably the extractant itself as the packing solvent. Figure 4 shows the packing process (or pack process or packing process) of an extraction column.

[0152] An aqueous solution of the mixed REE salts (but excluding Ce) or the mixed PGM salts is loaded onto the extraction column, respectively.

[0153] The REE ions or PGM complexes are eluted from the packed column with an aqueous solution of mineral acid by isocratic, linear gradient and / or stepwise gradient elution modes and / or gradient modes of eluent flow rate.

[0154] The eluted fraction is then concentrated by distillation, ion exchange and / or membrane filtration techniques to form a further concentrated fraction containing individual and / or groups of REEs or individual and / or groups of PGMs, and the eluent is recovered and recycled. Other separation techniques can also be used to recover and reuse the eluent (e.g., azeotropic distillation, centrifugation, evaporation, liquid-liquid extraction, etc.).

[0155] It was found during the course of this invention that one of the REEs, namely cerium (Ce), reacts differently with the complexing agents (or complexing agents or complex-forming agents or complexing agents) examined. In accordance with this finding, Ce was apparently oxidized to a higher oxidation state (+4) in the presence of organophosphorus extractants, forming a very stable complex that could not be eluted from the subject extraction column, even using the highest concentrations of mineral acids. It is therefore preferable to deplete the incoming REE mixture (or inflowing REE mixture) of Ce by hydrometallurgical methods prior to the chromatography process (or step) and use a Ce-free REE mixture (or a mixture of REEs without Ce) as the feed material (or feed material).

[0156] Even though it may be possible to separate all the REEs or all the PGMs in one (or a single) chromatographic step, in an industrial separation process it is preferred to first separate the incoming mixture of REEs or PGMs into several sub-groups, followed by a second chromatographic separation, where the groups of REEs or PGMs are further separated into individual REEs or individual PGMs.

[0157] A typical flow diagram of the process according to the present invention is shown in Figure 5, in which REE concentrate or PGM containing material obtained from a commercial source is introduced as a feed solution after mineralization with a suitable acid. The choice of acid for mineralization depends on the chemistry of the REE or PGM as well as safety and cost considerations. Currently, the preferred acids for the REEs are believed to be mineral acids (e.g., hydrochloric, sulfuric, nitric or phosphoric acid). Thus, the salts of the REEs are preferably chlorides (or chlorides or chlorides), sulfates (or sulfates), nitrates (or nitrates) or phosphates (or phosphates). Additionally, the preferred acid for PGMs is believed to be hydrochloric acid or royal acid (i.e., a 3:1 mixture of HCl / HNO3 (v / v)). Therefore, the PGM is preferably in the form of its anionic chloro complex.

[0158] However, one of ordinary skill in the art will understand upon reading this specification that still other acids / salts may be used. Also, one skilled in the art will know how to convert (or convert) a salt of an REE to another salt, if necessary.

[0159] With respect to REEs, the materials that can be separated are provided as REE concentrates (containing primarily salts of the REEs or oxides of the REEs). The REE salts or RRE oxides are first dissolved in a mineral acid of choice. Therefore, a further feedstock preparation step is performed in which the mixture of REEs (as described above) is reduced (or depleted) of the problematic cerium (Ce). For simplicity of description of this disclosure, the invention will be described using the nitrates (or nitrate salts or nitrate salts) of the REEs and nitric acid. One skilled in the art will appreciate that the process (or step or treatment or method) using other acids will be the same as using nitric acid / nitrates.

[0160] The Ce-depleted REE nitrates (or nitrate salts) are introduced into a feed solution system (or feed solution tank) 10, which comprises one or more mixing tanks and a feed solution tank (or feed solution tank). The nitrates of the REEs are dissolved in an aqueous solution of nitric acid (HNO3) (about 1-1.5 molar) to give a concentration of about 1-100 mg / l, such as about 50 mg / l of REEs, and introduced into a feed liquor tank 10.

[0161] With regard to PGMs, materials from which they can be separated include minerals containing PGMs, secondary material scrap, among others, discarded electronic scrap, used automotive catalytic converters, used batteries, used electric lamps, super alloys, jewellery scrap and industrial waste (e.g. plating solutions and plating sludge). The material containing the PGMs is first dissolved in a selected medium (or media) (as described below).

[0162] Due to their noble nature, PGMs are often dissolved and stabilized in solution by complexation with appropriate ligands. PGMs are known to form a range of complexes with a variety of different ligands. From a technical and commercial point of view, the chloride system is the most cost-effective and widely used medium, where all PGMs can be brought into solution and concentrated. Therefore, in illustrating this disclosure, the invention is illustrated using PGM chloro complexes and aqua regia (ie, a 3:1 mixture of HCl / HNO3 (v / v)) as the complexing media. Those skilled in the art will appreciate that the process using other complexing ligands (or complexed ligands (or ligands)) will be the same as when using aqua regia.

[0163] The mixed PGM chloro-complex solution (or mixed PGM chloro-complex solution) is introduced into one or more feed solution tanks 10′ (or feed solution tanks 10′), where the PGM concentration is about 1 to 100 mg / l (for example, about 50 mg / l).

[0164] Next, the aqueous solution of REE nitrates (or REE nitrates) contained in the feed solution tank 10 (or feed solution tank 10) is introduced into the group separation unit 11 (or group separation unit 11) via the supply line 12 (or feed line 12). Then, in a similar manner, the solution of PGM chloro complex contained in the feed solution tank 10' (or feed solution tank 10') is introduced into the group separation unit 11' (or group separation unit 11') via the supply line 12' (or feed line 12').

[0165] The group separation unit comprises one or more liquid chromatography units. The liquid chromatography units comprise a plurality of large volume high pressure extraction columns, one for each of the REEs and PGMs, wherein the extraction columns comprise a suitable extractant, which is chemically bound to bare silica particles. The extractant with REE ion complex forming properties is preferably an organophosphorus compound. The extractant with PGM complex forming properties is preferably an organic compound with amine or sulfur functionality. It has the general formula: [ka]

[0166] During the ceremony, R3 is H, or C1-C4 alkyl; R 1 and R 2 is independently a lipophilic (or lipophilic) hydrocarbon group or modified hydrocarbon, such as an alkyl, aryl, or ester group, such as those having 6 to 20 carbon atoms. Currently, the preferred complexing agents (or complexing agents or complex-forming agents or complexation agents) are di-(2-ethylhexyl)phosphoric acid (HDEHP), di-(2,4,4-trimethylpentyl)phosphinic acid (H[TMPeP]) and 2-ethylhexyl, 2-ethylhexylphosphonic acid (H[(EH)EHP]), aliquat-336 [N(CH3)4], and dioctyl sulfide [S(CH2)2]. Lists of other extractants are provided elsewhere in this disclosure.

[0167] The solid support onto which the selected extractant is immobilized is preferably a porous RP-silica particle, but may be any convenient solid material suitable for liquid chromatography. Currently, the preferred solid support is small pore or large surface area porous RP-silica with particle size of 5-45 μm and pore size of 60-100 Å.

[0168] The above RP-silica may be modified by physically immobilizing a desired type of extractant. In this disclosure, HDEHP, (H[TMPeP]), (H[(EH)EHP]), aliquat-336 [N(CH3)4], and di-octyl sulfide [S(CH2)2] are mentioned as references. Such an extractant is R 1 and R 2 It is assumed that the group is physically bound to the porous RP-silica by a bond between the carbon (C) of the group and the alkyl group of the RP-silica (e.g., some form of physicochemical bond or, e.g., van der Waals interaction). Different amounts and types of extractant in the extraction column result in different retention capacities, and therefore different loading capacities, of different REE and / or PGM ions. A person skilled in the art will easily find out what kind (or type) of extractant (or extractant) or what amount of extractant (or extractant) is suitable for the intended separation and purification of REEs or PGMs.

[0169] Extraction columns for the separation of REEs and / or PGMs typically have an internal diameter of 600-1200 cm and a bed length of 25-50 cm. However, the limits (or boundaries) so indicated may be extended without departing from the scope of the invention.

[0170] The separation unit (or separation unit) of the REE group or the separation unit (or separation unit) of the PGM group preferably comprises more than one extraction chromatography column (or extraction chromatography column) (as explained above). The columns are preferably arranged in parallel, with each of the columns being operated batch wise. Columns arranged in parallel may be operated in series, thereby allowing for a semi-continuous process.

[0171] A predetermined volume / concentration of feed solution (or supply solution) (containing mixed REEs with Ce depleted (or excluded)) (originating from tank 10) is filled (or loaded) into extraction column 11. In the same manner, the mixed PGM chloro complex solution (or mixed PGM chloro complex solution) (coming from tank 10') is filled (or loaded or loaded) into extraction column 11'. The acid concentration in both the REE and PGM feed solutions is maintained at the same level as the initial concentration of the acid in the eluent, and the pre-determined volume / concentration of the feed solution is calculated to be sufficiently lower than the theoretical capacity of the respective column (i.e. the amount of extractant in the column) to allow quantitative retention.

[0172] After packing (or loading or loading), the REEs or PGMs are eluted from the respective extraction columns (with appropriate eluent acids and appropriate eluent acid concentrations) (from the eluent mixing system 20 for REEs or the eluent mixing system for PGMs). The REE eluent mixing system and the PGM eluent mixing system are capable of mixing the incoming water, concentrated acid and recycled acid (of various concentrations) streams, thereby delivering the required eluent concentration (as described further below).

[0173] Separation of REE subgroups or PGM subgroups is usually achieved by linear and / or stepwise concentration gradient and / or flow gradient elution modes.

[0174] The pressure at which an extraction column is operated depends on, among other parameters, the set pressure of the column tube, the particle size of the inert solid support material, the packing density, and the length of the bed of the extraction column. In the present invention, the pressure at which the extraction column is operated during the elution of the REEs is typically between 50 and 100 bar.

[0175] The extraction column is typically operated at ambient temperature, but can also be operated at higher temperatures (e.g., 20-60° C.). A preferred extraction column temperature according to the present invention is 60°C.

[0176] The respective retention times of the REEs or PGMs are highly stable and reproducible from one chromatographic run to the next, provided that the eluent acid concentration, extraction gradient, and eluent flow rate are kept constant. Thus, fractions of individual REEs or individual PGMs may be collected based on retention time. However, retention times are preferably periodically verified (or checked) using a metal specific detector (or detectors) (eg Microwave Plasma Emission Spectrometry (MP-AES)). A rivulet split of the eluate leaving the extraction column is introduced into an MP-AES detector, which allows quantitative identification of each REE or PGM ion.

[0177] The separated REE or PGM subgroups are collected in their own dedicated tanks for further processing.

[0178] Each extraction column was then prepared (or preconditioned) for the next cycle by flushing it with an eluent acid solution, respectively, having approximately the same acid concentration as the feed solution containing the mixture of REEs or PGMs.

[0179] The subgroups of REEs or PGMs eluted from the extraction columns are substantially diluted compared to those of the feed solutions (or supply solutions) loaded onto the respective extraction columns. Thus, the eluted REE subgroup or PGM subgroup, respectively, are preferably concentrated to a certain concentration in an eluent recovery unit to recover and recycle the acid and generate a more concentrated fraction for further processing.

[0180] The final concentration (or up-concentration) of the REE subgroup fraction or the PGM subgroup fraction may be performed by various methods, among others by dilution, ion exchange capture or membrane filtration or by a combination thereof. Those skilled in the art will understand that each of the separated REE fractions (or fractions) or separated PGM fractions (or fractions) is concentrated separately, and that such fractions (or fractions) may be concentrated by a variety of methods.

[0181] Independently of the method used for the final concentration (or final concentration or up-concentration or up-concentration), the concentrated REE subgroup fractions or concentrated PGM subgroup fractions are recovered (or collected) in fraction tanks (or fraction tanks) 41, 42 and 43 or fraction tanks (or fraction tanks) 41', 42' and 43', respectively. The concentrated REE fraction or the concentrated PGM fraction may be further processed in the same facility, or one or more of the fractions may be converted to other salts (e.g. carbonates), or the metals may be precipitated, dried, and finally sold as the final product, respectively.

[0182] Preferably, the REE concentration of the REE subgroup fraction or the PGM concentration of the PGM subgroup fraction is, after final concentration (or final concentration or up-concentration or up-concentration), 50-100 g REE / L nitric acid or 50-100 g PGM / L hydrochloric acid, regardless of the final concentration method used.

[0183] The separated and finally concentrated (or final concentrated or up-concentrated or up-concentrated) fraction (or fraction) of the group of REEs (tanks 41, 42, 43) or the separated and finally concentrated (or final concentrated or up-concentrated or up-concentrated) fraction (or fraction) of the group of PGMs (tanks 41', 42', 43') are then introduced into a single component separation unit 50 (or single component separation unit 50) or a single component separation unit 50' (or single component separation unit 50'), respectively. The REE single component separation unit 50 or the PGM single component separation unit 50' comprises one or more extraction columns arranged in parallel or series, each directed to each of the fractions from tanks 41, 42, 43 or tanks 41', 42', 43'. The separation of each of the REEs or PGMs may be carried out using the same extraction columns and using the same range of operational parameters as described with reference to the group separation unit 11 (or group separation unit 11) or the group separation unit 11' (or group separation unit 11'), respectively.

[0184] The packing (or loading or loading) of the extraction columns in the REE single component separation unit 50 or the PGM single component separation unit 50' corresponds to the packing (or loading or loading) of the extraction columns in unit 11 or unit 11', respectively. The eluent acids for eluting each REE from the extraction column 50 are mixed in the eluent mixing unit 20 and introduced through the eluent line 51 . Similarly, the eluent acids for eluting each PGM from the extraction column 50' are mixed in the eluent mixing unit 20' and introduced through the eluent line 51'.

[0185] The elution of each REE or PGM from each loaded extraction column is performed by varying the concentration of the appropriate eluent acid, using a stepwise or linear concentration gradient mode or flow gradient mode, or a combination thereof. For a given acid concentration, the retention time (or retention time or retention time) is reproducible. An MP-AES detector or corresponding instrument is used on a thin stream of the eluate to distinguish (or identify) the individual REE or PGM peaks, respectively.

[0186] The mixture of REE or PGM components intended for storage (or stockpiling) and subsequent separation (or separation) are collected (or collected) in separate eluate tanks 62 or 62', respectively. Even though FIG. 5 shows only a few eluate tanks, one skilled in the art will appreciate that there is one tank for each REE or PGM of interest.

[0187] Also, one skilled in the art will appreciate that by adjusting the degree of peak overlap, the level of purity of any individual REE fraction or any individual PGM fraction can be controlled, thereby allowing fractions to be produced at purity levels according to specific customer specifications. Collection of narrow peak fractions can result in highly pure individual REEs or highly pure individual PGMs (e.g., greater than 99% purity). In the case of both REEs and PGMs, in uses (or applications) with lower purity requirements, broader peak fractions may allow overlap (or overlapping or overlapping) with adjacent fractions (or fractions).

[0188] The REE fraction in eluate tank 62 or the PGM fraction in eluate tank 62' is substantially diluted compared to the solution loaded onto the respective extraction column. Typically, the total concentration of REEs or PGMs in the eluate is 1-3 g / L, respectively. The individual REE or PGM fractions are then respectively introduced into a final concentration (or final concentration or up-concentration or up-concentration) eluent recovery unit 70 or a final concentration (or final concentration or up-concentration or up-concentration) eluent recovery unit 70', which concentrates the single component fractions of REE or PGM (as described with reference to the eluent recovery unit 40 or 40', respectively).

[0189] The eluent acid (e.g., NHO3 as described above) recovered from the REE fraction is collected in tanks 25, 26, 27 via lines 25*, 26*, 27* respectively, depending on the strength of the acid. Similarly, the eluent acid (e.g., HCl as described above) recovered from the PGM fraction is collected in tanks 25', 26', 27' via lines 25**, 26**, 27** respectively, depending on the strength of the acid.

[0190] The concentrated eluates from the REE eluate recovery unit 70 (or recovery unit 70) or the PGM eluate recovery unit 70' (or recovery unit 70') are collected in concentrate tanks 72 or 72', respectively.

[0191] The fraction of overlapping REE peaks is in tank 61 and may be concentrated in eluent regeneration unit 70 and introduced into REE recycle tank 90 and recycled through line 91 to REE group separation unit 11 or REE single component separation unit 50. Similarly, the fraction of overlapping PGM peaks, in tank 61', may be concentrated in eluent regeneration unit 70', introduced into PGM recycle tank 90', and recycled through line 91' to PGM group separation unit 11' or PGM single component separation unit 50'.

[0192] Preferably, the REE concentrate in tank 72 is eventually converted to carbonates in a conversion unit 80 by neutralization with ammonia and addition of carbonic acid or CO2. The carbonate fraction is dried and collected in carbonate tank 82 or may be calcined to produce an oxide. The separated carbonates or oxides of the individual REEs, the carbonates (containing overlapping peaks of two REEs) from the storage tank 62, or their corresponding oxides, may be sold to their users for further processing, for example depending on their final use.

[0193] Preferably, the PGM concentrate in tank 72' is eventually converted to metallic PGMs in conversion unit 80' (or conversion unit 80') by reduction with hydrogen gas or other reducing agent. The metallic PGMs are filtered off and collected in a holding tank 82' (or storage tank 82'). The separated PGMs of individual metals emerging from storage tank 62', including overlapping peaks of PGMs, may be sold to their users for further processing, for example depending on their final use.

[0194] A person skilled in the art will understand that for all the above liquid chromatography units, two or more extraction columns may be arranged in parallel or in series, or in a rack setup (which allows an operator and / or a control system to change the column setup), for example by changing the sequence of consecutive columns, disconnecting one or more columns to replace an extraction column without disturbing the column elution and / or operation. EXAMPLES

[0195] (Example) Example 1 Use of various mineral acids as eluents for REEs To compare the elution of various acids, a test run was performed using a lab-scale extraction column containing di-(2-ethylhexyl) phosphoric acid (HDEHP) as the extractant and RP-silica as the inert solid support. The acids tested were HNO3, HCl, H2SO4, and H3PO4. Figure 6 represents the elution profiles obtained from elution using various mineral acids. Figures 7 and 8 show the difference in retention time (or dissimilarity or difference) and resolution (or separation ability or resolution) between lighter REEs (or light REEs) and SEG-REEs under the same chromatographic conditions using an HDEHP column. The REEs show small differences in retention times for all acids. However, H3PO4 shows no ability to elute the heaviest REEs. The remaining three acids show good resolution among the REEs tested. HNO3 and HCl appear to show better resolution than H2SO4.

[0196] The conclusion that can be drawn from these tests is that HNO3, HCl and H2SO4 are good choices and can be used as eluents, with HNO3 and HCl being slightly better, whereas H3PO4 cannot elute all the REEs.

[0197] Example 2 Separation of REEs using various types of extractants Test runs were performed under the same chromatographic conditions using laboratory-scale extraction columns (containing the same amount of extractant but a different type of extractant). Figure 9 shows the elution profiles of the lighter REEs and SEG-REEs obtained during the tests. Of the three ligands tested, HDEHP showed the greatest retention capacity for all REEs examined, followed by (H[TMPeP]) and (H[(EH)EHP]).

[0198] The results that can be derived from these tests are that HDEHP is suitable for group separation of all REEs and for individual separation of lighter REEs and SEG-REEs, whereas (H[TMPeP]) can be used for individual separation of early heavy REEs (i.e. Tb~Er)+Y. (H[(EH)EHP]) could be used for the individual separation of the late and heavy REEs (Tm, Yb and Lu)+Sc, which form very stable complexes, especially with HDEHP, and to a lesser extent with (H[TMPeP]).

[0199] Example 3 Separation of REEs (as a function of the amount of extractant) Test runs were performed using laboratory-scale extraction columns containing varying amounts of HDEHP (i.e., varying extractant densities). Figure 10 shows the retention profiles of the REEs obtained from the separation of all the REEs under the same chromatographic conditions, but with different amounts of extractant. From these chromatograms it is clear that the retention capacity of the extraction column as well as the degree of separation between adjacent REE peaks becomes better as the amount of extractant increases.

[0200] The results that can be derived from such tests are that HDEHP is suitable for group separation of REEs as well as for individual separation of most REEs (e.g., La~Er+Y), whereas H([HTMeP]) can be used for individual separation of REEs heavier than Er (i.e., Tm, Yb, Lu) and Sc. These form very stable complexes with HDEHP and are difficult to elute using mineral acids as eluents. H([EHEHP]) could have been used for individual and / or group separation of REEs using H3PO4 as eluent, which showed a weaker elution capacity as mentioned above.

[0201] Example 4 Separation of REEs (as a function of eluent flow rate (u)) A laboratory-scale extraction column (containing HDEHP as the extractant and reverse phase silica as the inert solid support) was used to test the effect of eluent flow rate (u) on the chromatographic separation of REEs. A feed solution containing a mixture of several REEs was loaded onto the extraction column and then eluted with an appropriate concentration of HNO3 by varying the eluent flow rate (u) from 0.5 mL / min to 2 mL / min, while keeping other chromatographic conditions constant. Figures 11 and 12 respectively show the peak widths (w) of individual REEs and the resolution (Rs) between adjacent REE peaks resulting from the above tests.

[0202] The results of this test are that an eluent flow rate (u) of 1.5 mL / min probably gives the best results, i.e. narrower peak widths for individual REEs and better resolution between adjacent REE peaks. Therefore, a flow rate of 1.5 mL / min is probably the optimal flow rate (i.e., 4.3 m for a 120 cm diameter column). 3 / hr).

[0203] Example 5 Resolution of REEs (as a function of temperature (T)) A laboratory-scale extraction column (containing HDEHP as the extractant and reverse-phase silica as the inert solid support) was used to test the effect of column temperature (T) on the chromatographic separation of REEs. A feed solution containing a mixture of several REEs was loaded onto the extraction column and then eluted with an appropriate concentration of HNO3 at an optimal flow rate (1.5 mL / min) by varying the column temperature (T) from 20 °C to 60 °C, while keeping other chromatographic conditions constant. Figures 13 and 14 respectively show the peak widths (w) of individual REEs and the resolution (Rs) between adjacent REE peaks resulting from the above tests.

[0204] The results from this test are that higher column temperatures give better results, both in terms of the peak width (w) of individual REE peaks and the resolution between adjacent REE peaks. Therefore, considering the maximum temperature possible with reversed-phase silica being ≦70° C., a column temperature of 60° C. is chosen as a compromise optimum.

[0205] Example 6 REE column packing test A semi-preparative extraction column (1 cm (id) x 25 cm (L), 10 μm (pd), 1000 Å (pore size)) packed with reverse phase silica containing 31 mmol of HDEHP was used to test the column loading. In this test, a feed solution was used, containing a mixture of several REEs at a concentration of 46 mg / mL of total REOs. A series of overloading tests were performed by injecting 1 mL, 2.5 mL and 5 mL of the feed solution into the above extraction column in low loading test, medium loading test and high loading test, respectively. Therefore, elution was performed using an appropriate concentration of HNO3 (as eluent), a flow rate of 4 mL / min, and a column temperature of 60 °C, which were found to be optimal parameters according to the present invention.

[0206] Figure 15 shows the elution profiles of REEs at low, medium and high column loadings. As shown in the figure, as the amount of feed solution (or supply solution) loaded onto the column (i.e., the degree of loading) changes, the peak shape and breakthrough retention time of each REE, as well as the resolution between adjacent REE peaks, change. However, acceptable separation of individual REEs and / or groups of REEs remains very high load.

[0207] Example 7 PGM Group Separation Test Figure 16 shows the separation of PGMs (as a group) from other base metals using a DOS extraction column.

[0208] Example 8 Separate testing of individual PGMs FIG. 17 shows the individual separation (or solid or individual isolation) of Pd from other PGMs using a DOS extraction column.

[0209] Example 9 Separate testing of individual PGMs FIG. 18 shows the individual separation (or solid or individual separation) of Rh from other PGMs using a DETA extraction column.

[0210] Example 10 Pilot-scale separation testing REE group separation Using a pilot-scale extraction column, a test run was performed that included group separation of the REEs into three subgroups: light REEs (La, Pr, and Nd), SEG-REEs (Sm, Eu, and Gd), and heavy REEs (Tb~Er+Y). The column dimensions are 20 cm (id) by 35 cm (L) and are packed with narrow pore RP-silica [15 μm (pd) and 100 Å (pore size)] and the density of the extractant is 48 mmol HDEHP / g. The incoming REE mixture (or influent REE mixture) (Ce-depleted (or depleted) and containing 400 mg of TREO) was loaded onto the extraction column described above and eluted with HNO3 using a combination of concentration and flow gradient elution modes (or flow gradient elution modes) with a column temperature of 60 °C. First, to elute the light REEs, a linear gradient elution was performed over 9 min (1.25 M to 3 M HNO3, eluent flow rate of 800 mL / min). This was followed by an isocratic elution (7 M HNO3, eluent flow rate of 1600 mL / min) for another 9 min to elute the SEG-REEs and heavy REEs. Finally, the column was preconditioned (1.25 M HNO3, eluent flow rate of 1600 mL / min, 2 min) (after a total of 20 min of cycling) in preparation for the next group separation cycle. Figure 19 shows a representative chromatogram and elution profile obtained in this test.

[0211] Separation of individual lighter REEs (but excluding Ce) A pilot-scale extraction column was used to conduct test runs that involved the separation of the individual lighter REEs into their single components (i.e., La, Pr, and Nd). The extraction column dimensions are 20 cm (id) by 35 cm (L) and packed with narrow pore RP-silica [15 μm (pd) and 100 Å (pore size)], with an extractant density of 48 mmol HDEHP / g. After final concentration (or final concentration or up-concentration or up-concentration) in the distillation unit / ion exchange unit to the desired level of concentration, the light REE fraction from the group separation step (or group separation step) was loaded (or loaded) onto the above extraction column and separated in isocratic elution mode (1.25 M HNO3 solution, flow rate (or flow velocity or flow rate) of 1.6 L / min, column temperature of 60 °C). Figure 20 shows a representative chromatogram obtained in this test, in which the three light REEs (La, Pr, Nd) are separated (or baseline resolved) and quantitatively eluted from the column within 10 minutes.

[0212] Separation of individual SEG-REEs A pilot-scale extraction column was used to conduct a test run that included the individual separation of the SEG-REEs into their single components. The column dimensions are 20 cm (id) by 35 cm (L) and are packed with narrow pore RP-silica [10 μm (pd) and 100 Å (pore size)] and the density of the extractant is 48 mmol HDEHP / g. After final concentration (or final concentration or up-concentration or up-concentration) to the desired level of concentration in the distillation unit, the SEG-REE fraction from the group separation step (or group separation step) was loaded (or loaded) onto the above extraction column and separated (or separated) by using linear gradient elution mode (initial 1.25 M HNO3 to final 7 M HNO3, 8 min, flow rate of 1.6 L / min, column temperature of 60 °C). Finally, the column was preconditioned (1.25 M HNO3 (same concentration as the starting concentration of the gradient) for 2 min (total 10 min cycle), same flow rate, and column temperature as indicated above) in preparation for the next separation cycle. FIG. 21 shows a representative chromatogram obtained in this test. As can be seen, the three SEG-REEs (Sm, Eu, Gd) are separated (or baseline separated) and eluted quantitatively from the column.

[0213] Separation of individual early heavy REEs (or early heavy REEs) + Y Using a pilot-scale extraction column, a test run was conducted that included the individual separation of the early and heavy REEs (Tb, Dy, Ho, Er) and Y. The column dimensions are 20 cm (id) by 35 cm (L) and are packed with narrow pore RP-silica [15 μm (pd) and 100 Å (pore size)], and the density of the extractant is 48 mmol H([HTMeP]) / g. After final concentration in a distillation unit to the desired level of concentration, the fractions (containing the early heavy REEs (Tb,Dy)+Y) obtained from the group separation step were loaded onto the extraction column and separated using isocratic elution mode (1.5 M HNO3 solution, 1.6 L / min flow rate, 60 °C column temperature). FIG. 22 shows a representative chromatogram obtained from this test. As can be seen in Figure 19, the early heavy REEs (Tb, Dy) and Y are separated (or baseline resolved) and quantitatively eluted from the column within 10 minutes.

[0214] Separation of individual slow and heavy REEs (or late heavy REEs) A pilot-scale extraction column was used to perform a test run that included the individual separation of the slow and heavy REEs (Tm, Yb, Lu). The column dimensions are 20 cm (id), 35 cm (L) and packed with RP-silica [15 μm (pd) and 100 Å (pore size)], and the density of the extractant is 48 mmol H([EHEHP]) / g. After final concentration in a distillation unit to the desired level of concentration, the fractions (containing late and heavy REEs (Tm, Yb, Lu)) obtained from the group separation step were loaded onto the above chromatographic column and separated using isocratic elution mode (1.25 M HNO3 solution, flow rate of 1.6 L / min, column temperature of 60 °C). FIG. 23 shows a representative chromatogram obtained from this test. As can be seen, the three heavy REEs of interest (Tm, Yb and Lu) are separated (or baseline resolved) and quantitatively eluted from the column within 10 minutes.

Claims

1. A stationary phase for the chromatographic separation and / or purification of REEs and / or PGMs, said stationary phase comprising an extractant, said extractant being immobilized on a support; the support comprises reverse-phase silica particles, the reverse-phase silica particles being characterized by an average pore size of less than 2,000 Å; the extractant comprises an organic compound having complexing properties capable of retaining and separating REE and / or PGM by forming complexes with ions of various REE and / or PGM, the complexes having different stability constants; The extractant is impregnated into the support, and the impregnation conditions are the following two conditions: a temperature in the range of 35°C to 80°C; Ultrasonic Treatment Process A stationary phase under at least one of the following conditions:

2. The reverse phase silica particles have an average pore size of less than 300 Å and a pore size of less than 170 m ２ 10. The stationary phase of claim 1, characterized by a surface area greater than 1000 nm / g.

3. The reverse phase silica particles have an average pore size in the range of 50 Å to 150 Å and a mean pore size of 200 to 600 m ２ 10. The stationary phase of claim 1, characterized by a surface area in the range of 0.15 wt. / g.

4. A stationary phase described in claims 1 to 3, wherein the temperature is within the range of 50°C to 60°C.

5. 10. The stationary phase of claim 1, wherein the extractant comprises an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or one or more combinations thereof.

6. The extractant may comprise an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or a combination of one or more thereof, and may have the following general formula: 【Chemistry 1】 [In the formula, R １ and R ２ is independently a lipophilic hydrocarbon or modified hydrocarbon, said hydrocarbon being selected from the group comprising C6-20 alkyl, C6-20 aryl; R ３ is H, C1-C6 alkyl and C1-C6 aryl.

2. The stationary phase of claim 1, having

7. The extractants were di-(2-ethylhexyl)phosphoric acid (DHEHP), di-(2,4,4-trimethylpentyl)phosphinic acid (H[TMPeP]) and 2-ethylhexyl, 2-ethylhexylphosphonic acid (H[(EH)EHP]), Aliquat-336 [N(CH ３ ) ４ ], dioctyl sulfide [S(CH ２ ) ２ ], or one or more combinations thereof.

8. An extraction column for the chromatographic separation and / or purification of REEs and / or PGMs, said extraction column comprising a stationary phase according to claim 1.

9. 1. A method for producing a stationary phase for the chromatographic separation and / or purification of REEs and / or PGMs, the method comprising the following steps (i) and (ii): (i) providing a support, said support comprising reverse phase silica particles, said reverse phase silica particles characterized by an average pore size of less than 2,000 Å; (ii) impregnating the reversed-phase silica particles of step (i) with at least one extractant, the at least one extractant is an organic compound having complexing properties that allow it to retain and separate the REEs and / or PGMs, the complexing properties being due to the formation of complexes with ions of different REEs and / or PGMs, the complexes having different stability constants; Including, The extractant is impregnated into the support, and the impregnation conditions are the following two conditions: a temperature in the range of 35°C to 80°C; Ultrasonic Treatment Process The method is performed under at least one of the following conditions:

10. The reverse phase silica particles have an average pore size of less than 300 Å and a pore size of less than 170 m ２ 10. The method of claim 9, characterized by a surface area greater than 1000 W / g.

11. The reverse phase silica particles have an average pore size in the range of 50 Å to 150 Å and a mean pore size of 200 to 600 m ２ 10. The method of claim 9, wherein the surface area is in the range of 1 / g.

12. The method of claim 9, wherein the temperature is in the range of 50°C to 60°C.

13. 10. The method of claim 9, wherein the extractant comprises an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or one or more combinations thereof.

14. The extractant may comprise an organophosphorus compound, an amine, a quaternary ammonium salt, a sulfur-containing organic compound, or a combination of one or more thereof, and may have the following general formula: 【Chemistry 2】 [In the formula, R １ and R ２ is independently a lipophilic hydrocarbon or modified hydrocarbon, said hydrocarbon being selected from the group comprising C6-20 alkyl, C6-20 aryl; R ３ is H, C1-C6 alkyl and C1-C6 aryl.

14. The method of claim 13, comprising:

15. The extractants were di-(2-ethylhexyl)phosphoric acid (DHEHP), di-(2,4,4-trimethylpentyl)phosphinic acid (H[TMPeP]) and 2-ethylhexyl, 2-ethylhexylphosphonic acid (H[(EH)EHP]), Aliquat-336 [N(CH ３ ) ４ ], dioctyl sulfide [S(CH ２ ) ２ ], or a combination thereof.

16. A method for separating and / or purifying REE and / or PGM from an aqueous solution containing REE and / or PGM, the method comprising the following steps (a) to (d): (a) Providing an extraction column according to claim 8; (b) loading the aqueous solution containing the REE and / or PGM into an extraction column; (c) using an eluent mode to separate the REE and / or PGM; and (d) Eluting the separated REE and / or PGM from the extraction column. A method comprising:

17. The eluent mode is an eluent concentration mode and / or an eluent flow rate gradient mode, and optionally, the eluting step is performed in accordance with the following (i), (ii), or (iii): (i) an isocratic concentration of an eluent mineral acid in said aqueous solution; (ii) a linear gradient of the concentration of an eluent mineral acid in said aqueous solution; or (iii) the concentration of a step-wise gradient of the eluent mineral acid in said aqueous solution; The method of claim 16, wherein the method is carried out by

18. The following steps: (e) recovering the fraction of the eluate containing REE and / or PGM, (f) A final concentration step of the eluted REE and / or PGM fractions, and (g) recovering the eluent mineral acid and water; 18. The method of claim 16 or 17, further comprising at least one of:

19. 17. The method of claim 16, wherein the elution and collection of fractions in steps (d) and (e) are controlled in such a manner as to recover REE and / or PGM from one or more extraction columns, wherein the REE and / or PGM have similar retention volumes in a given extraction column.

20. 17. The method of claim 16, wherein the solution of REE and / or PGM loaded onto the column comprises an acid matrix, said matrix allowing the REE and / or PGM to be quantitatively retained by a given column.

21. 21. The method of claim 20, wherein the quantitatively retained REE and / or PGM are REE and are eluted with an eluent, increasing the acid concentration and / or the flow rate of the eluent to elute first the light REE group, then the SEG-REE group, and then the heavy REE+Y group.

22. (i) the light REE group is absent or contains at least one of La, Pr and Nd; (ii) the SEG-REE group is absent or contains at least one of Sm, Eu, and Gd; (iii) the heavy REE+Y group is absent or comprises at least one of Tb, Dy, Ho, Er, Tm, Yb, Lu and Y; 22. The method of claim 21, wherein at least one of the three groups (i), (ii) and (iii) is present.

23. The REE and / or PGM include PGM, and the PGM are quantitatively retained and eluted using an eluent, increasing the concentration of acid and / or the flow rate of the eluent; (i) a first group of PGMs is eluted first, the first group of PGMs including at least one of Pd and Pt; (ii) a second group of PGMs is eluted second, the second group of PGMs comprising at least one of Rh, Ru, and Ir; 21. The method of claim 20.

24. 19. The method of claim 18, wherein the elution and recovery of fractions in steps (d) and / or (e) is controlled to recover pure fractions of each metal derived from REE and / or PGM.

25. 18. The method of claim 16 or 17, wherein the fractions containing the group of REEs, each REE, group of PGMs or PGMs are recovered and concentrated to recover an eluate by distillation, ion exchange, membrane filtration, centrifugation, solvent extraction, evaporation, azeotropic distillation, liquid-liquid extraction or a combination thereof.

26. 18. The method of claim 16 or 17, wherein one or more of the concentrated fractions are converted to an insoluble salt or oxide of the metal, respectively, which are recovered and dried.

27. 18. The method according to claim 16 or 17, wherein the elution is carried out under a pressure of 50 to 100 bar.

28. 18. The method of claim 16 or 17, wherein the aqueous solution is acidic.

29. The quantitatively retained REE is eluted using an eluent, increasing the acid concentration and / or the flow rate of the eluent to first elute the light REE group, then the SEG-REE group, and then the heavy REE+Y group; The light REE group mainly includes La, Pr, and Nd; the SEG-REE group includes Sm, Eu, and Gd; The heavy REE+Y group mainly comprises Tb, Dy, Ho, Er, Tm, Yb, Lu and Y; 17. The method of claim 16.

30. The quantitatively retained PGMs are eluted using an eluent, increasing the acid concentration and / or the eluent flow rate to first elute a first group of PGMs and then a second group of PGMs; the first group of PGMs includes Pd and Pt; The second group of PGMs includes Rh, Ru, and Ir.

17. The method of claim 16.

31. 17. The method of claim 16, wherein the elution and collection of the fractions is controlled to collect pure fractions of each REE or PGM.

32. 1. A method for industrial separation and purification of individual REEs and / or PGMs from a mixed aqueous solution of REEs and / or PGMs, comprising the steps of: (i) First, the REE and / or PGM are separated into subgroups of REE and PGM by the method according to claim 17, and then (ii) One or more of said REE and / or PGM subgroups are subjected to the following steps (e), (f) and (g): (e) recovering the fraction of the eluate containing REE and / or PGM, (f) A final concentration step of the eluted REE and / or PGM fractions, and (g) recovering the eluent mineral acid and water; and separated by at least one of The elution and recovery of fractions in steps (d) and / or (e) are controlled to recover pure fractions of each metal derived from REE and / or PGM. method.

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