DE102017010590A1 - Enrichment of rare earth metals from mineral substrates - Google Patents

Abstract

The present invention comprises a process for the enrichment of cations of the elements Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in aqueous solution of mineral Substrates by means of organic phosphonic acids of the formula (1) according to claim 1 as the main process step. For this purpose, the corresponding phosphonic acid derivatives of the formulas (100) to (109) are preferred for the main process step, it being possible to optimize the main process step by adjusting the pH and / or by adding chloride. In its development, the invention independently comprises two pretreatment steps for the substrate, for the extraction solution in each case two post-treatment steps and a final treatment step, which are combined with the main process step to form a generally applicable overall process in Apsruch 10. Particularly advantageous, the proposed enrichment process is characterized by a high efficiency and environmental friendliness.

Description

The invention relates to a method for enriching cations of the rare earth metals scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (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) in aqueous In its developments, the invention further relates to a method for enriching these rare earth metals in the presence of complexing agents and quaternary ammonium salts and the transfer of rare earth metals from an aqueous to a hydrophobic phase.

The extraction of rare earth metals (hereinafter referred to as SEM) is extremely expensive. Individual methods for this are described, for example, in: Bernhard Adler, Ralf Müller, "Rare earth metals - extraction, use and recycling", Universitätsverlag Ilmenau 2014 summarized. The pure salts of these elements must be separated from the ores, which in principle contain only mixtures of the SEM compounds in addition to other compounds, via elaborate separation processes. In the first step, the ores are digested by treatment, for example, with alkali or mineral acids, such as hydrochloric or sulfuric acid. In part, the ores, such as monazite or bastnaesite or xenotime or gadolinite or euxenite, are also subjected to high temperature chlorination to form a mixture of chlorides.

• - Fraktionierte Kristallisation oder Fällung;
• - Absorption in einem Ionenaustauscher und anschließende selektive Elution mit einem Komplexbildner, wie beispielsweise Ethylendiamintetraessigsäure (nachfolgend als EDTA bezeichnet), Nitrilotriessigsäure (nachfolgend als NTA bezeichnet), 1-Hydroxyethyl-1,1-diphosphonsäure (nachfolgend als HEDPA bezeichnet), Aminotris(methylenphosphonsäure) (nachfolgend als ATMP bezeichnet), Ethylendiamintetra(methylenphosphonsäure) (nachfolgend als EDTMP bezeichnet) und Diethylentriaminpenta(methylenphosphonsäure (nachfolgend als DTPMP bezeichnet);
• - Flüssig-Flüssig-Extraktion aus einer wässrigen Phase in ein hydrophobes organisches Lösemittel, wobei in dem Lösemittel geeignete Komplexbildner, wie Tri-n-butylphosphat (nachfolgend als TBP bezeichnet), Di(2-ethylhexyl)hydrogenphos-phat (nachfolgend als DEHPA bezeichnet), oder langkettige quarternäre Ammoniumsalze, wie Tetradecylammoniumchlorid enthalten sind.

In a further step, the mixtures of the SEM salts obtained from the digested material are subjected to further separation processes:

• Fractionated crystallization or precipitation;
• Absorption in an ion exchanger and subsequent selective elution with a complexing agent such as ethylenediaminetetraacetic acid (hereinafter referred to as EDTA), nitrilotriacetic acid (hereinafter referred to as NTA), 1-hydroxyethyl-1,1-diphosphonic acid (hereinafter referred to as HEDPA), aminotris (methylenephosphonic acid (hereinafter referred to as ATMP), ethylenediaminetetra (methylenephosphonic acid) (hereinafter referred to as EDTMP) and diethylenetriaminepenta (methylenephosphonic acid (hereinafter referred to as DTPMP);
• Liquid-liquid extraction from an aqueous phase into a hydrophobic organic solvent, wherein in the solvent suitable complexing agents, such as tri-n-butyl phosphate (hereinafter referred to as TBP), di (2-ethylhexyl) hydrogenphosphate (hereinafter referred to as DEHPA ), or long-chain quaternary ammonium salts such as tetradecylammonium chloride are included.

Due to resource scarcity, export restrictions and the high industrial demand for SEM, their recovery from industrial waste is becoming increasingly important. Even in such industrial waste, such as, for example, in slagging of motor vehicle catalysts or glass waste containing SEM, the SEM are generally produced as mixtures. Depending on the type of waste generated, this requires complex specific adjustments of individual recovery processes.

To improve the liquid-liquid extraction or to separate the individual SEM, the use of ionic liquids has been proposed; in this regard, current methods are in the Treatise: Kaiying Wang, Hertanto Adidharma, Maciej Radosz, Pingyu Wan, Xin Xu, Christopher K. Russell, Hanjing Tian, Maohong Fan, Jiang Yu, "Recovery of rare earth elements with ionic liquids", Green Chemistry 2017 , Edition 119, pages 4469-4493. For an overview of hydrophobic ionic liquids, see: Yukinobu Fukaya, Hiroyuki Ohno, "Hydrophobic and polar ionic liquids", Physical Chemistry Chemical Physics 2013, Issue 15, pages 4066-4072.

From the treatise: Justin A. Bogart, Connor A. Lippincott, dr. Patrick J. Carroll, Eric J. Shelter, "An Operationally Simple Method for Separating the Rare Earth Element Neodymium and Dysprosium," Angewandte Chemie International Edition 2015, Vol. 127, Issue 28, pp. 8340-8343 Tris [2- (1 ', 1'dimethylethyl) hydroxy-laminato) benzylamine (hereinafter referred to as H ₃ TriNOx) has become known as a highly selective ligand for trivalent SEM cations, with which the cations Nd ³⁺ and Dy ^{3+ are} highly selective separate from each other.

A major disadvantage of the previous separation and enrichment of SEM is not only in their complexity, the high number of required steps and in the equipment required, but also in the use of concentrated, highly corrosive mineral acids such as alkalis and large Volumes of organic solvents. These methods are not only costly, but also require a lot of effort for a sufficient environmental protection.

H ₃ TriNOx is only soluble in organic solvents but not in water. Complexation of trivalent SEM cations succeeds only in the presence of strong bases, such as amides. Compared to other ligands for trivalent SEM cations, the synthesis of H ₃ TriNOx is complex.

The invention has for its object to provide a simplified method for the enrichment of trivalent SEM cations in a liquid phase of mineral substrates available.

In the present invention, a mineral substrate is understood as meaning a solid inorganic substance mixture which, in addition to further constituents, contains one or more SEMs in the form of a sparingly soluble compound or mixture thereof in neutral water. These may be, for example, in the form of oxides and / or silicates untreated or aftertreated ores or slagged industrial waste.

The above object is achieved by the feature combination of claim 1 in an inventive manner.

in die wässrige Phase. Die Phosphonsäure der Formel (1) weist m Phosphonsäure-Gruppen -PO(OH)₂ auf, welche jeweils alle über ein C-Atom kovalent an einen gemeinsamen organischen Rest angebunden sind, wobei m einer natürlichen Zahl von 1 bis 10 entspricht.The proposed enrichment process of SEM from a mineral substrate comprises as a main process step an extraction of cations of at least one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu from a mineral substrate present in an aqueous suspension by means of an organic phosphonic acid of the formula (1) dissolved in water:

into the aqueous phase. The phosphonic acid of the formula (1) has m phosphonic acid groups -PO (OH) ₂ , which are each covalently attached via a carbon atom to a common organic radical, where m corresponds to a natural number of 1 to 10.

An extraction of SEM cations from mineral substrates in the aqueous phase with a phosphonic acid of the formula (1) can be effected even at 25 ° C, when the aqueous phase has a pH of 4.5 or less. A pH value between 0.5 and 3 is advantageous for the fastest possible extraction. This is technically feasible simply by stirring the mineral substrate in an aqueous solution of the phosphonic acid.

At standstill of the accumulation of SEM cations in the aqueous phase in the implementation of the main process step, the solution is filtered from the mineral substrate. Particularly advantageously, the filtrate solution thus obtained is nehrmalig for the same extraction process, each with a new batch of minerlischem substrate used, which takes place in the case of too high a pH again acidified with the phosphonic acid of formula (1). The possible number of these cycles of the main process step is limited only by the solubility of the phosphonic acid of the formula (1) and all other solutes in the reused solution, but mainly by an optionally critical volume increase.

The simplest representative of the phosphonic acid of the formula (1) is methylphosphonic acid, with which the extraction of SEM from mineral substrates succeeds. However, this requires higher concentrations of methylphosphonic acid compared to those phosphonic acids which have more than one phosphonic acid group. Since the pH of the phosphonic acid increases simultaneously with the number of phosphonic acid groups on the common organic radical R, the pH can be kept particularly advantageously constant over the entire extraction period in comparison to methylphosphonic acid even with lower concentrations of such a polybasic phosphonic acid better extraction of the SEM cations is effected.

Acid strength and / or the lowest possible pH value are not per se a guarantee for the success of the extraction of SEM from mineral substrates. For example, the extraction of SEM cations does not succeed with methylsulfonic acid. Surprisingly, phosphonic acids of the formula (1) have a concentration of 1 mol L ^-1 in water in about the same extraction capacity with respect to SEM cations as an aqueous hydrochloric acid solution of a concentration of 6 mol L ^-1 . If the mineral substrate has a high silicate content, disadvantageous gelling of the aqueous phase is often observed when using hydrochloric acid, which makes filtration technically more difficult. Such gelling of the aqueous phase is not observed when carrying out the main process step using the phosphonic acid of the formula (1).

The development of the proposed invention with regard to the main method step will be discussed below.

der Phosphonsäure der Formel (1) sowie Mischungen davon als erste Variante des Hauptverfahrensschrittes besonders geeignet, wobei wobei der Rest R¹ ist ausgewählt aus der Gruppe:

• -(CH₂)_s-CH₃, -CH₂-(CF₂)_s-CF₃,
• -Isopropyl,
• -Isobutyl,
• -Phenyl,
• -3,5-Dimethylphenyl,
• -Pentafluorophenyl,
• -3,5-Bis(trifluoromethyl)phenyl.

For carrying out the main process step, derivatives of the formulas (100) to (109) are:

the phosphonic acid of the formula (1) and mixtures thereof are particularly suitable as the first variant of the main process step, where the radical R ¹ is selected from the group:

• - (CH ₂ ) _s -CH ₃ , -CH ₂ - (CF ₂ ) _s -CF ₃ ,
• isopropyl,
• isobutyl,
• phenyl,
• -3,5-dimethylphenyl,
• -Pentafluorophenyl,
• -3,5-bis (trifluoromethyl) phenyl.

Here q is a natural number from 1 to 5, s is an integer from 0 to 19 and X is an H or F atom.

Derivatives of the formula (100) also include HEDPA, where for the radical R ¹ corresponds to a methyl group. The derivatives (100), (103), (105), (107) and (109) are known and partially commercially available. The derivatives (101) and (102) are accessible, for example, by means of Michaelis-Abusov reactions and combinations thereof, and in some cases are also available commercially. ATMP, EDTMP and DTPMP according to formulas (104), (106) and (108) are accessible by variants of the Mannich reaction and are also commercially available.

The derivatives of formulas (100) to (109) are not only excellent complexing agents for SEM cations with optimal acid strengths and good pH buffering properties, but are characterized by both a good solubility in water and in organic solvents. Further, the derivatives of formulas (100), (104), (105), (106), (108) and (109) are readily biodegradable and inexpensive. These derivatives are few corrosive than mineral acids, for example hydrochloric acid. Although these derivatives have pK _a values of about 0.8 of the first to 12.6 of the last protolysis step and are thus about 40 to 50 powers of ten weaker than hydrochloric acid, only concentrations between SEM cations from mineral substrates are usually 0.2 to 1.5 mol L ^-1 required. Thus, even the main process step of the proposed method is superior to conventional methods for enrichment of SEM in aqueous solutions.

The choice of a suitable extractant, which has both a sufficient acid strength and complexing ability of SEM cations and a good solubility, is by no means trivial. For example, EDTA is totally unsuitable for the extraction of SEM cations from mineral substrates in place of the phosphonic acid of formula (1).

In a second advantageous variant of the main process step, the aqueous phase is additionally adjusted to a pH of between 1 and 3 by addition of hydrochloric acid. In this way, both the presence of additional acid and chloride an increase in the extraction rate of SEM cations in the aqueous phase can be accomplished. If the pH of the aqueous phase is less than 1, the extraction rate is reduced. It is therefore necessary that the protolysis equilibrium of the phosphonic acid of the formula (1) is not suppressed in the proposed main process step. Chloride forms chlorido complexes with the SEM cations.

einem Guanidiniumkation [(H₂N)₂C=NH₂]⁺ mit n gleich 1 entspricht oder in der Summe insgesamt n quartemisierte N- und / oder P-Atome aufweist und n eine natürliche Zahl bedeutet, wobei die quarternisierten N- und / oder P-Atome gleiche, teilweise gleiche oder verschiedene organische Reste aufweisen und die organischen Reste jeweils über ein C-Atom an das quarternisierte N-Atom und / oder an das quartenisierte P-Atom kovalent angebunden sind. In a third advantageous variant of the main process step, the aqueous phase additionally contains a metal-free chloride salt of the formula (2): where the cation:

corresponds to a guanidinium cation [(H ₂ N) ₂ C = NH ₂ ] ⁺ with n equal to 1 or has a total of n quaternized N and / or P atoms and n is a natural number, the quaternized N and / or P atoms have the same, partially identical or different organic radicals and the organic radicals are each covalently attached via a C atom to the quaternized N atom and / or to the quartenized P atom.

This third variant of the proposed main process step is indicated when the pH of the aqueous phase is already too low. By choosing a metal-free cation, introduction of disadvantageous cargo of additional foreign metals is avoided. Ammonium chloride as an additive is not suitable, the ammonium cation (NH ₄ ⁺ ) also inhibits the phosphonic acid of the formula (1) with respect to their complexing properties.

After carrying out the main process step or the main process step according to one of the three other variants with a not further treated mineral substrate, for example with an ore or with a slag obtained from industrial waste, in addition to the SEM cations are usually a variety of other metal ions in the aqueous phase in front.

Below, therefore, two pretreatment steps are disclosed in the development of the proposed method, with which at least a portion of unwanted foreign cations by pretreatment of the mineral substrate before carrying out the main process step are removable.

The first pretreatment step comprises the alkaline pretreatment of the mineral substrate with an aqueous solution of a metal-free hydroxide salt of the formula (3): [A ² ] ^{n ⊕} (OH ^⊖ ) _n 3 wherein, independently of the chloride salt of the formula (2), the cation: [A ² ] ^{n ⊕} corresponds again to a guanidinium cation [(H ₂ N) ₂ C = NH ₂ ] ⁺ with n equal to 1 or has a total of n quaternized N and / or P atoms and n is a natural number, the quaternized N and / or P atoms again have the same, partially identical or different organic radicals and the organic radicals are each covalently bound via a C atom to the quaternized N atom and / or to the quaternized P atom. The cation of the hydroxide salt of the formula (3) and the cation of the chloride salt of the formula (2) are the same or different.

The first pretreatment step can be carried out, for example, in the form of an extraction of a finely ground mineral substrate with an aqueous solution of the hydroxide salt of the formula (3). Here are the elements: B, Al, Ga, Si, Ge, Ti, Zr, Hf, V, Nb, Ta and Zn in solution, the SEM remain in the mineral substrate.

The hydroxide salt of the formula (3) has the same properties as strong electrolytes and is thus a sufficiently strong base for the extraction of the above-mentioned elements in the form of their hydroxo complexes from a pH of more than 12. At the same time, the cation of Hydroxide salt, for example tetramethylammonium or tetra-n-butylammonium, detergent properties, which particularly advantageous via surface activation of the substrate in addition to the extraction of the aforementioned elements accelerated. By using the hydroxide salt of formula (3) the entry of foreign metal ions in the mineral substrate is excluded.

The second pretreatment step comprises acid pretreatment of the mineral substrate with an aqueous acetic, glycolic or citric acid solution or mixtures thereof. The second pretreatment step is for example in the form of an extraction of a finely ground mineral substrate with an aqueous solution of citric acid. Here are the elements: Li, Na, K, Mg, Ca, Ba Sr, Al, Cr, Mo, W, Mn, Re, Fe, Co. Ni, Cu, Zn, Cd and Hg from a pH of equal to or less than 4.5 in solution. If the SEM contained in the mineral substrate are not present as carbonates, they remain in the mineral substrate after execution of the second pretreatment step.

The first and the second pretreatment step are interchangeable with respect to their implementation.

In the further development of the proposed method, two post-treatment steps are disclosed below, with which further fractions of remaining foreign ions can be removed from the aqueous phase obtained after carrying out the main process step.

The first post-treatment step comprises the post-treatment of the suspension obtained after carrying out the main process step by addition of hydrogen sulfide and optionally subsequent filtration of the solid containing it.

The second post-treatment step comprises the post-treatment of the suspension obtained after carrying out the main process step with an organic hydroxide salt of the formula (4): [A ³ ] ^n⊕ (OH ^⊖ ) _n 4 until a pH of not more than 8 is achieved, and optionally subsequent filtration of the contained solid. Here, independently of the hydroxide salt of the formula (3), the cation has: [A ³ ] ^{n ⊕} in the sum total of n quaternized N and / or P atoms, where n is a natural number. The quaternized N and / or P atoms of the cation of the hydroxide salt of the formula (4) have identical, partly identical or different organic radicals, the organic radicals in each case via a C atom to the quaternized N atom and / or covalently attached to the quartenized P atom.

geeignet, wobei die Reste R² bis R¹⁴ unabhängig voneinander und gleich, teilweise gleich oder verschieden sind, wobei die Reste R² bis R⁵ ausgewählt sind aus der Gruppe:

• -(CH₂)_s-CH₃,
• -CH₂-(CF₂)_s-CF₃,
• -Isopropyl,
• -Isobutyl,
• -Benzyl,
• -3,5-Dimethylbenzyl,
• -2,3,4,5-Pentafluorobenzyl,
• -3,5-Bis(trifluoroethyl)benzyl,
• -2-Hydroxyethyl,
• -2-Methoxyethyl,

wobei die Reste R⁶ bis R⁹ einem:

• Phenyl- oder
• 3,5-Dimethylphenyl- oder
• Pentafluorophenyl- oder einem
• 3,5-Bis(trifluoromethyl)phenyl-Substituenten

oder einem der Reste R² bis R⁵ entsprechen. Die Reste R¹⁰ bis R¹⁴ entsprechen einem der Reste R⁶ bis R⁹ oder alle oder teilsweise H-Atomen, r ist entweder 1 oder 2 und X¹ entspricht einem O- oder S-Atom.For the cation of the hydroxide salt of the formula (4), in particular derivatives of the formulas (200) to (218) are:

in which the radicals R ² to R ^{14 are} independently of one another and identical, in some cases identical or different, where the radicals R ² to R ^{5 are} selected from the group:

• - (CH ₂ ) _s -CH ₃ ,
• -CH ₂ - (CF ₂ ) _s -CF ₃ ,
• isopropyl,
• isobutyl,
• benzyl,
• -3,5-dimethyl benzyl,
• -2,3,4,5-Pentafluorobenzyl,
• -3,5-bis benzyl (trifluoroethyl)
• -2-hydroxyethyl,
• -2-methoxyethyl,

where the radicals R ⁶ to R ^{9 are} one:

• Phenyl or
• 3,5-dimethylphenyl or
• Pentafluorophenyl- or one
• 3,5-Bis (trifluoromethyl) phenyl-substituents

or one of the radicals R ² to R ⁵ correspond. The radicals R ¹⁰ to R ¹⁴ correspond to one of the radicals R ⁶ to R ⁹ or all or partially H atoms, r is either 1 or 2 and X ¹ corresponds to an O or S atom.

The proposed hydroxide salts of the formula (4), which comprise cations of the derivatives (200) to (218), have both proven to have good solubility in water and in organic solvents, such as, for example, toluene, THF, diethyl ether, methyl tert .-Butyl ether, trifluoromethylbenzene, dichloromethane, butanone and acetone, on.

Furthermore, the proposed cations of the formulas (200) to (218) of the hydroxide salt of the formula (4) show the advantageous property, in cooperation with the phosphonic acid of the formula (1) and in particular their derivatives of the formulas (100) to (109) To complex the trivalent cations of the SEM Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and from an aqueous phase to a non-water-miscible organic phase or into a hydrophobic ionic liquid, for example in a final treatment step. In the application of the proposed method to a particular mineral substrate, both the third variant of the main process step and the second post-treatment step are considered or required, the metal-free chloride salt of formula (2) and the organic hydroxide salt of formula (4) respectively identical cations, preferably those of the formulas (200) to (218).

The first and second post-treatment steps are interchangeable with respect to their implementation.

The first aftertreatment step is superfluous if the mineral substrate has a high content of sulfide before the Huptverfahrensschritt or its variants. In this case, the suspension or filtrate solution obtained after carrying out the main process step or its variants contains a sufficient amount of hydrogen sulphide to precipitate the remaining heavy metal cations: Cr, Mo, W, Mn, Re, Fe, Co. Ni, Cu, Zn, Cd and Hg, which takes place after adjustment of the pH by means of the second post-treatment step. After carrying out the first and second pretreatment step, the main process step or its variants, and the first and second post-treatment step, the residual SEM and alkali cations in the remaining aqueous phase or filtrate are enriched.

Below, therefore, a finishing treatment step is disclosed in development of the proposed method, which is provided after performing all the previous process steps for the separation of the SEM of alkali cations.

The final treatment step comprises extraction of the suspension or filtrate solution obtained after one or both after-treatment steps with an organic solvent or a hydrophobic ionic liquid and mixtures thereof, with subsequent removal of the resulting hydrophobic phase from the remaining aqueous phase. After the final treatment step, ions of the SEM are enriched in the hydrophobic phase. In this hydrophobic phase, the SEM cations are present as adducts of such phosphonic acid salts which are composed of phosphonates of the phosphonic acid of formula (1) and cations of the chloride salt of formula (2) and / or the hydroxide salt of formula (4) are. From this hydrophobic phase SEM cations with known and customary precipitation reactions, for example as oxalates, are separable.

1. (I) erster Vorbehandlungsschritt;
2. (II) zweiter Vorbehandlungsschritt;
3. (III) Hauptverfahrensschritt und / oder Variationen davon;
4. (IV) erster Nachbehandlungsschritt;
5. (V) zweiter Nachbehandlungschritt;
6. (VI) Schlussbehandlungsschritt.

In the following, the proposed enrichment process is summarized in all its developments in the sense of a generally applicable embodiment, wherein the enrichment process comprises the following steps:

1. (I) first pretreatment step;
2. (II) second pretreatment step;
3. (III) main process step and / or variations thereof;
4. (IV) first post-treatment step;
5. (V) second post-treatment step;
6. (VI) final treatment step.

Compared to conventional enrichment processes, the vogue enrichment process of SEM cations from a mineral substrate requires only a minimum of individual steps and amounts of water as well as organic solvents or hydrophobic ionic liquids. Furthermore, the appartive effort is limited only to simple stirring devices and mixing vessels.

Particularly advantageous relatively mild and environmentally friendly reagents are needed compared to highly corrosive reagents or solutions thereof conventional methods; The accumulating wastewater can be treated in conventional wastewater treatment plants.

The required energy expenditure is largely limited to the stirring and, if appropriate, heating in carrying out the main process step and the pretreatment steps to a maximum of 50 ° C .; all other optional partial process steps are feasible at room temperature.

The process is particularly advantageously applicable to a large number of mineral substrates, in particular to those obtained in recovery processes.

Thus, according to the state of the art, the proposed process is significantly more economical than the previous enrichment processes of SEM cations.

The present invention will be described in detail by the following two non-limiting examples. These examples include the use of the main process step for the enrichment of SEM cations from in each case two different mineral substrates (substrate 1, substrate 2), which prove the general simple applicability of the proposed method.

Substrate 1: calcium oxide-grafted components of motor vehicle catalysts, finely ground, containing: 2.89% by weight of Ce; 0.27% by weight of La; 0.08 wt.% Nd.

Substrate 2. Milled spectacle lenses / lenses from the optics industry, finely ground, containing: 6.97% by weight of La.

example 1

50 g of substrate 1 were stirred in a closed PVC beaker in 1 L of an aqueous HEDPA solution (c = 1 mol L ^-1 ) by means of a magnetic stirring fish at 25 ° C for 21 h. The pH of the solution before working up was 1.53. The result was a gray suspension with a strong smell of hydrogen sulfide, which after filtration twice a greenish clear solution (1107 g, about 1 L). The determination of the content of SEM by means of ICP-OES yielded the following recoveries: 59% Ce, 63% La, 86% Nd.

Example 2

167 g of substrate 2 were stirred in a closed PVC beaker in 1 L of an aqueous HEDPA solution (c = 1 mol L- ¹ ) by means of a magnetic stirring fish at 25 ° C for 72 h. The pH of the solution during the entire reaction was 1.42-1.44. The result was a colorless suspension, which after a single vacuum filtration on a fine filter an arblose clear solution (1028 g, about 0.99 L). The determination of the content of SEM by ICP-OES yielded recovery rates of 35% La.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited non-patent literature

• Written by: Kaiying Wang, Hertanto Adidharma, Maciej Radosz, Pingyu Wan, Xin Xu, Christopher K. Russell, Hanjing Tian, Maohong Fan, Jiang Yu, "Recovery of rare earth elements with ionic liquids", Green Chemistry 2017 [0005]
• Justin A. Bogart, Connor A. Lippincott, dr. Patrick J. Carroll, Eric J. Shelter, "An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium", Angewandte Chemie International Edition 2015, Vol. 127, Issue 28, pp. 8340-8343 [0006]

Claims (10)

Enrichment process of rare earth metals from a mineral substrate, characterized in that in a main process step from the mineral substrate present in an aqueous suspension by means of an organic phosphonic acid of the formula (1) dissolved in water:

Cations of at least one of the elements Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu are extracted into the aqueous phase, wherein the aqueous phase is a Has pH of 4.5 or less, wherein in formula (1) the m phosphonic acid groups -PO (OH) _{2 are} each covalently attached via a carbon atom to a common organic radical and m is a natural number of 1 to 10 corresponds. Enrichment method according to Claim 1 characterized in that the phosphonic acid of the formula (1) derivatives of the formulas (100) to (109):

and mixtures thereof, wherein the radical R ¹ is selected from the group: - (CH ₂ ) _s -CH ₃ , -CH ₂ - (CF ₂ ) _s -CF ₃ , -Isopropyl, -Isobutyl, -phenyl, - 3,5-dimethylphenyl-pentafluorophenyl, -3,5-bis (trifluoromethyl) -phenyl, where q is a natural number from 1 to 5, s is an integer from 0 to 19 and X is an H or F atom. Enrichment method according to one of Claims 1 or 2 characterized in that in the main process step, the aqueous phase is additionally adjusted by the addition of hydrochloric acid to a pH value between 1 and 3. Enrichment method according to one of Claims 1 to 3 characterized in that in the main process step the aqueous phase additionally contains a metal-free chloride salt of formula (2): wherein the cation:

corresponds to a guanidinium cation [(H ₂ N) ₂ C = NH ₂ ] ⁺ with n equal to 1 or has a total of n quaternized N and / or P atoms and n is a natural number, the quaternized N and / or P atoms have the same, partially identical or different organic radicals and the organic radicals are each covalently bound via a C atom to the quaternized N atom and / or to the quaternized P atom. Enrichment method according to one of Claims 1 to 4 characterized in that in a first pretreatment step the mineral substrate before carrying out the main process step with an aqueous solution of a metal-free hydroxide salt of the formula (3): [A ² ] ^{n ⊕} (OH ^⊖ ) _n 3 is pretreated with alkali, wherein, independently of the chloride salt of the formula (2), the cation: [A ² ] ^{n ⊕} corresponds again to a guanidinium cation [(H ₂ N) ₂ C = NH ₂ ] ⁺ with n equal to 1 or has a total of n quaternized N and / or P atoms and n is a natural number, the quaternized N and / or P atoms again have the same, partially identical or different organic radicals and the organic radicals are each covalently attached via a C atom to the quaternized N atom and / or to the quartenized P atom. Enrichment method according to one of Claims 1 to 4 characterized in that in a second pretreatment step, the mineral substrate is pretreated acidic before performing the main process step in a pretreatment step with an aqueous acetic acid, glycolic acid or citric acid solution or mixtures thereof. Enrichment method according to one of Claims 1 to 6 characterized in that in a first post-treatment step, the suspension obtained after carrying out the main process step is mixed with hydrogen sulfide and optionally subsequently filtered off from the containing solid. Enrichment method according to one of Claims 1 to 6 characterized in that in a second post-treatment step the suspension obtained after carrying out the main process step with an organic hydroxide salt of the formula (4): [A ³ ] ^n⊕ (OH ^⊖ ) _n 4 is brought to a pH of not more than 8 and optionally subsequently filtered from the containing solid, wherein independently of the hydroxide salt of the formula (3) the cation: [A ³ ] ^{n ⊕} in the sum total of n quaternized N and / or P atoms and n is a natural number, wherein the quaternized N or P atoms have the same, partially identical or different organic radicals and the organic radicals each have a C atom covalently attached to the quaternized N atom and / or to the quartenized P atom. Enrichment method according to Claim 8 characterized in that, in a final treatment step, the suspension or filtrate solution obtained after one or both post-treatment steps is extracted with an organic solvent or a hydrophobic ionic liquid and mixtures thereof, and the resulting hydrophobic phase is separated from the remaining aqueous phase. Enrichment method according to one of Claims 1 to 4 and claims 5 to 9, which comprises the following steps: (VII) first pretreatment step after Claim 5 ; (VIII) second pretreatment step Claim 6 ; (IX) Main process step according to one of Claims 1 to 4 ; (X) first post-treatment step after Claim 7 ; (XI) second post-treatment step after Claim 8 ; (XII) final treatment step after Claim 9 ,