阅读说明：本技术 一种二烷基氨基苯氧乙酸沉淀剂及其制备方法和应用 (Dialkylamino phenoxyacetic acid precipitator and preparation method and application thereof ) 是由 林锦池 王艳良 吴玉远 肖文涛 于 2020-11-24 设计创作，主要内容包括：本发明属于稀土资源回收领域,尤其涉及一种二烷基氨基苯氧乙酸沉淀剂及其制备方法和应用。本发明提供的二烷基氨基苯氧乙酸沉淀剂具有式(I)所示化学结构,其中,R1和R2独立地选自C_6～C_(12)的烷基。与现有工业应用沉淀剂相比,本发明提供的二烷基氨基苯氧乙酸沉淀剂具有更高的沉淀能力,沉淀效率高,沉淀颗粒较大,有利于稀土沉淀与水相的分离；另外该沉淀剂的水相残留低,并可重复使用,节约经济成本,提高生产效率。与现有其他烷基苯氧羧酸类沉淀剂(比如仲辛基苯氧乙酸)相比,由于本发明提供的沉淀剂具有O和N两种配位点,因此能吸附更多稀土离子,这使得它在平衡时的饱和负载能力明显更高,所需用量更少,可节约工艺成本。(The invention belongs to the field of rare earth resource recovery, and particularly relates to a dialkyl amino phenoxyacetic acid precipitator and a preparation method and application thereof. The dialkyl amino phenoxyacetic acid precipitator provided by the invention has a chemical structure shown in formula (I), wherein R1 and R2 are independently selected from C 6 ～C 12 Alkyl group of (1). Compared with the existing industrial application precipitator, the dialkyl amino phenoxyacetic acid precipitator provided by the invention has higher precipitation capacity, high precipitation efficiency and larger precipitation particles, and is beneficial to separation of rare earth precipitation and a water phase; in addition, the water phase residue of the precipitator is low, and the precipitator can be repeatedly used, so that the economic cost is saved, and the production efficiency is improved. Precipitate with other existing alkyl phenoxy carboxylic acidsCompared with the reagent (such as sec-octyl phenoxyacetic acid), the precipitator provided by the invention has two coordination sites of O and N, so that more rare earth ions can be adsorbed, the saturated loading capacity of the precipitator at the equilibrium is obviously higher, the required dosage is less, and the process cost can be saved.)

1. A dialkylaminophenoxyacetic acid precipitant having a chemical structure represented by formula (I):

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl group of (1).

2. The dialkylaminophenoxyacetic acid precipitant according to claim 1, wherein the dialkylaminophenoxyacetic acid precipitant is one or more compounds having a structure represented by formula (I-1) to formula (I-4):

3. a preparation method of a dialkyl amino phenoxyacetic acid precipitator is characterized by comprising the following steps:

a) mixing p-nitrophenol, sodium haloacetate, alkali, alcohol and water, heating and refluxing for reaction to obtain p-nitrophenoxycarboxylate;

b) carrying out hydrogenation reduction on the p-nitrophenoxy carboxylate to obtain p-aminophenoxy carboxylate;

c) reacting the p-aminophenoxy carboxylate with halogenated hydrocarbon to carry out alkylation reaction, and then acidifying the reaction product to obtain a dialkyl amino phenoxyacetic acid precipitator with the structure shown in the formula (I);

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl group of (1).

4. The preparation method according to claim 3, wherein the reaction temperature in step a) is 90-110 ℃; the reaction time is 0.5-6 h.

5. A method for enriching rare earth is characterized by comprising the following steps:

A) saponifying the dialkylaminophenoxyacetic acid precipitator according to any one of claims 1 to 2 or the dialkylaminophenoxyacetic acid precipitator prepared by the preparation method according to any one of claims 3 to 4, mixing the saponified product with a feed liquid containing rare earth ions, and performing solid-liquid separation to obtain a precipitate;

B) and eluting the precipitate with inorganic acid solution to obtain rare earth enriched solution and regenerated dialkylaminophenoxyacetic acid precipitant.

6. The method according to claim 5, wherein in step A), the saponification is performed by: saponifying the dialkylaminophenoxyacetic acid precipitator and hydroxide in water;

the hydroxide is ammonia monohydrate; by NH₃The mass ratio of the ammonia monohydrate to the dialkyl amino phenoxyacetic acid precipitator is (0.01-0.3): 1.

7. the method according to claim 5, wherein in step A), the rare earth ions contained in the feed liquid comprise one or more of lanthanum ion, cerium ion, praseodymium ion, neodymium ion, samarium ion, europium ion, gadolinium ion, terbium ion, dysprosium ion, holmium ion, erbium ion, thulium ion, ytterbium ion, lutetium ion, scandium ion and yttrium ion; the total concentration of rare earth ions in the feed liquid is 0.05-50 g/L; the pH value of the feed liquid is 5-7.

8. The method according to claim 5, wherein in step B), the acid in the inorganic acid solution comprises one or more of hydrochloric acid, nitric acid and sulfuric acid; the concentration of the inorganic acid solution is 0.5-12 mol/L.

9. The method according to claim 5, wherein the temperature of the elution in the step B) is 50-130 ℃.

10. A saponification precipitant characterized by having a chemical structure represented by formula (II):

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl groups of (a); m is the residue remaining after removal of-OH from the hydroxide.

Technical Field

The invention belongs to the field of rare earth resource recovery, and particularly relates to a dialkyl amino phenoxyacetic acid precipitator and a preparation method and application thereof.

Background

The ionic rare earth ore is a rare earth ore which is special in China and is rich in medium and heavy rare earth elements. The chemical precipitation method is widely applied to industry for enriching rare earth elements in ionic rare earth ore leachate, and commonly used precipitating agents comprise oxalic acid, ammonium bicarbonate, magnesium oxide, calcium oxide and the like. The precipitant has large processing capacity and simple operation process, but has more problems, such as higher price of the oxalic acid precipitant, high oxalic acid residue in the precipitation mother liquor, higher toxicity and easy environmental pollution; the precipitator cannot be recycled, so that the economic cost is high; the tail liquid has ammonia nitrogen pollution and is difficult to treat; the more important problems are small size of the precipitate, long aging period and difficult solid-liquid separation.

Therefore, it is necessary to develop a new precipitant to realize the efficient and economical enrichment of rare earth.

Disclosure of Invention

In view of the above, the present invention provides a dialkylamino phenoxyacetic acid precipitant, and a preparation method and an application thereof, and the dialkylamino phenoxyacetic acid precipitant provided by the present invention is applied to the enrichment of low-concentration rare earth, which can shorten the precipitation period, improve the enrichment rate, and can realize the reuse of the precipitant.

The invention provides a dialkyl amino phenoxyacetic acid precipitator, which has a chemical structure shown in a formula (I):

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl group of (1).

Preferably, the dialkylaminophenoxyacetic acid precipitator is one or more of compounds shown in formulas (I-1) to (I-4):

the invention provides a preparation method of a dialkyl amino phenoxyacetic acid precipitator, which comprises the following steps:

a) mixing p-nitrophenol, sodium haloacetate, alkali, alcohol and water, heating and refluxing for reaction to obtain p-nitrophenoxycarboxylate;

b) carrying out hydrogenation reduction on the p-nitrophenoxy carboxylate to obtain p-aminophenoxy carboxylate;

c) reacting the p-aminophenoxy carboxylate with halogenated hydrocarbon to carry out alkylation reaction, and then acidifying the reaction product to obtain a dialkyl amino phenoxyacetic acid precipitator with the structure shown in the formula (I);

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl group of (1).

Preferably, in the step a), the reaction temperature is 90-110 ℃; the reaction time is 0.5-6 h.

The invention provides a method for enriching rare earth, which comprises the following steps:

A) after the dialkyl amino phenoxyacetic acid precipitator in the technical scheme or the dialkyl amino phenoxyacetic acid precipitator prepared by the preparation method in the technical scheme is saponified, the dialkyl amino phenoxyacetic acid precipitator is mixed with feed liquid containing rare earth ions, and solid-liquid separation is carried out to obtain a precipitate;

B) and eluting the precipitate with inorganic acid solution to obtain rare earth enriched solution and regenerated dialkylaminophenoxyacetic acid precipitant.

Preferably, in step a), the saponification mode is as follows: saponifying the dialkylaminophenoxyacetic acid precipitator and hydroxide in water;

the hydroxide is ammonia monohydrate; by NH₃The mass ratio of the ammonia monohydrate to the dialkyl amino phenoxyacetic acid precipitator is (0.01-0.3): 1.

preferably, in the step a), the rare earth ions contained in the feed liquid include one or more of lanthanum ions, cerium ions, praseodymium ions, neodymium ions, samarium ions, europium ions, gadolinium ions, terbium ions, dysprosium ions, holmium ions, erbium ions, thulium ions, ytterbium ions, lutetium ions, scandium ions and yttrium ions; the total concentration of rare earth ions in the feed liquid is 0.05-50 g/L; the pH value of the feed liquid is 5-7.

Preferably, in step B), the acid in the inorganic acid solution comprises one or more of hydrochloric acid, nitric acid and sulfuric acid; the concentration of the inorganic acid solution is 0.5-12 mol/L.

Preferably, in the step B), the elution temperature is 50-130 ℃.

The invention provides a saponification precipitator which has a chemical structure shown in a formula (II):

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl groups of (a); m is the residue remaining after removal of-OH from the hydroxide.

Compared with the prior art, the invention provides a dialkyl amino phenoxyacetic acid precipitator and a preparation method and application thereof. The dialkyl amino phenoxyacetic acid precipitator provided by the invention has a chemical structure shown in formula (I), wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl group of (1). Compared with the existing industrial application precipitator (such as ammonium bicarbonate and ammonium carbonate), the dialkyl amino phenoxyacetic acid precipitator provided by the invention has higher precipitation capacity, high precipitation efficiency and larger precipitation particles, and is beneficial to separation of rare earth precipitation and a water phase; in addition, the water phase residue of the precipitator is low, and the precipitator can be repeatedly used, so that the economic cost is saved, and the production efficiency is improved. Compared with other existing alkyl phenoxy carboxylic acid precipitants (such as sec-octyl phenoxy acetic acid), the precipitant provided by the invention has two coordination sites of O and N, so that more rare earth ions can be adsorbed, the saturated loading capacity of the precipitant is obviously higher in balance, the required dosage is less, and the process can be savedAnd (4) cost.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a dialkyl amino phenoxyacetic acid precipitator, which has a chemical structure shown in a formula (I):

wherein R1 and R2 are independently selected from C₆～C₁₂More specifically may be C₆Alkyl radical, C₇Alkyl radical, C₈Alkyl radical, C₉Alkyl radical, C₁₀Alkyl radical, C₁₁Alkyl or C₁₂An alkyl group.

In the invention, the dialkylaminophenoxyacetic acid precipitant can be specifically one or more of the compounds shown in formulas (I-1) to (I-4):

the invention also provides a preparation method of the dialkyl amino phenoxyacetic acid precipitator, which comprises the following steps:

a) mixing p-nitrophenol, sodium haloacetate, alkali, alcohol and water, heating and refluxing for reaction to obtain p-nitrophenoxycarboxylate;

b) carrying out hydrogenation reduction on the p-nitrophenoxy carboxylate to obtain p-aminophenoxy carboxylate;

c) reacting the p-aminophenoxy carboxylate with halogenated hydrocarbon to carry out alkylation reaction, and then acidifying the reaction product to obtain a dialkyl amino phenoxyacetic acid precipitator with the structure shown in the formula (I);

wherein R1 and R2 are independently selected from C₆～C₁₂More specifically may be C₆Alkyl radical, C₇Alkyl radical, C₈Alkyl radical, C₉Alkyl radical, C₁₀Alkyl radical, C₁₁Alkyl or C₁₂An alkyl group.

In the preparation method provided by the invention, the p-nitrophenol, the sodium haloacetate, the alkali, the alcohol and the water are firstly mixed. Wherein the sodium haloacetate is preferably sodium chloroacetate; the base is preferably sodium hydroxide; the alcohol includes, but is not limited to, one or more of ethanol, propanol, isopropanol, and butanol, preferably ethanol for economical reasons; the molar ratio of the p-nitrophenol to the sodium haloacetate is preferably 1: (1-2), specifically 1: 1.5; the molar ratio of the p-nitrophenol to the base is preferably 1: (0.5-2), specifically 1: 1; the dosage ratio of the p-nitrophenol to the alcohol is preferably 0.1 mol: (20-100) mL, specifically 0.1 mol: 50 mL; the dosage ratio of the p-nitrophenol to the water is preferably 0.1 mol: (20-100) mL, specifically 0.1 mol: 50 mL; preferably, a certain amount of catalyst is further added into a mixed system consisting of the p-nitrophenol, the sodium haloacetate, the alkali, the alcohol and the water, the catalyst is preferably KI, and the dosage ratio of the catalyst to the p-nitrophenol is preferably (0.1-0.5) g: 0.1mol, in particular 0.2 g: 0.1 mol. In the present invention, the specific process of mixing is preferably as follows: mixing p-nitrophenol, alcohol and water, mixing with alkali, and finally mixing with sodium haloacetate and catalyst.

In the preparation method provided by the invention, after the materials are uniformly mixed, heating and refluxing are carried out to carry out Williamson reaction. Wherein the reaction temperature is preferably 90-110 ℃, and specifically can be 90 ℃, 95 ℃, 100 ℃, 105 ℃ or 110 ℃; the reaction time is preferably 0.5-6 h, and specifically can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6 h. After the reaction is finished, removing alcohol in the reaction product to obtain the p-nitrophenoxy carboxylate product. Among them, the alcohol removal method is preferably rotary evaporation.

In the preparation method provided by the invention, after the p-nitrophenoxycarboxylate is obtained, the p-nitrophenoxycarboxylate is subjected to hydrogenation reduction. In the present invention, the specific steps of the hydrogenation reduction preferably include: firstly, mixing p-nitrophenoxycarboxylate, a catalyst and a solvent, then heating a mixed system to a reaction temperature, and introducing hydrogen into the mixed system to perform a reduction reaction. The catalyst is preferably a Pd/C catalyst, and the Pd loading amount of the Pd/C catalyst is preferably 5-15 wt.%, and specifically can be 10 wt.%; the solvent is preferably ethanol; the dosage ratio of the catalyst to p-nitrophenol serving as a raw material for preparing the p-nitrophenoxy carboxylate is preferably (1-10) mg: 0.1mol, in particular 5 mg: 0.1 mol; the reaction temperature is preferably 60-90 ℃, and specifically can be 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃ or 90 ℃; the time of the reduction reaction is preferably 2-8 h, and specifically can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 6h, 7h or 8 h. And after the hydrogenation reduction is finished, carrying out solid-liquid separation on the obtained reduction product and removing the solvent by rotary evaporation to obtain the p-aminophenoxy carboxylate.

In the preparation method provided by the invention, after the p-aminophenoxy carboxylate is obtained, alkylation reaction is carried out on the p-aminophenoxy carboxylate. In the present invention, the specific steps of the alkylation reaction preferably include: mixing and reacting p-aminophenoxy carboxylate, alkali metal hydroxide, halogenated hydrocarbon and a solvent. Wherein the alkali metal hydroxide includes, but is not limited to, sodium hydroxide; the halogenated hydrocarbon is selected according to the R1 and R2 substituents of the dialkylaminophenoxyacetic acid precipitant to be produced, including but not limited to one or more of 1-bromohexane, 1-bromooctane, 1-bromononane, and 1-bromododecane; the solvent is preferably ethanol; the molar ratio of the alkali metal hydroxide to p-nitrophenol serving as a raw material for preparing the p-aminophenoxy carboxylate is preferably (0.5-2): 1, specifically 1: 1; the molar ratio of the halogenated hydrocarbon to p-nitrophenol serving as a raw material for preparing the p-aminophenoxy carboxylate is preferably (1-3): 1, specifically 2: 1; the temperature of the mixing reaction is preferably 60-90 ℃, and specifically can be 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃ or 90 ℃; the mixing reaction time is preferably 4-8 h, and specifically can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8 h.

In the preparation method provided by the invention, after the alkylation reaction is finished, the reaction product is acidified. Wherein, the acid solution used for acidification includes but is not limited to one or more of hydrochloric acid solution, sulfuric acid solution, nitric acid solution and phosphoric acid solution, and is preferably hydrochloric acid solution for economic reasons; the concentration of the acid liquor is preferably 0.5-12 mol/L, and specifically can be 0.5mol/L, 1mol/L, 2mol/L, 4mol/L, 6mol/L, 8mol/L, 10mol/L and 12 mol/L; the acidification temperature is preferably 15-35 ℃, and specifically can be 25 ℃ (room temperature); the pH value of the final point of acidification is preferably 1-3, and specifically can be 2. After the acidification is finished, performing rotary evaporation, water washing and drying on the acidification product to obtain the dialkyl amino phenoxyacetic acid precipitator with the structure shown in the formula (I).

Compared with the existing industrial application precipitator (such as ammonium bicarbonate and ammonium carbonate), the dialkyl amino phenoxyacetic acid precipitator provided by the invention has higher precipitation capacity, high precipitation efficiency and larger precipitation particles, and is beneficial to separation of rare earth precipitation and a water phase; in addition, the water phase residue of the precipitator is low, and the precipitator can be repeatedly used, so that the economic cost is saved, and the production efficiency is improved. Compared with other existing alkyl phenoxy carboxylic acid precipitants (such as sec-octyl phenoxy acetic acid), the precipitant provided by the invention has two coordination sites of O and N, so that more rare earth ions can be adsorbed, the saturated loading capacity of the precipitant is obviously higher during balance, the required dosage is less, and the process cost can be saved.

The invention also provides a method for enriching rare earth, which comprises the following steps:

A) after the dialkyl amino phenoxyacetic acid precipitator in the technical scheme or the dialkyl amino phenoxyacetic acid precipitator prepared by the preparation method in the technical scheme is saponified, the dialkyl amino phenoxyacetic acid precipitator is mixed with feed liquid containing rare earth ions, and solid-liquid separation is carried out to obtain a precipitate;

B) and eluting the precipitate with inorganic acid solution to obtain rare earth enriched solution and regenerated dialkylaminophenoxyacetic acid precipitant.

In the enrichment method provided by the invention, the precipitant is firstly saponified, and the specific mode is preferably as follows: and (3) carrying out saponification reaction on the dialkyl amino phenoxyacetic acid precipitator and hydroxide in water. Wherein, the hydroxide includes but is not limited to one or more of sodium hydroxide, potassium hydroxide and ammonium monohydrate, and is preferably ammonium monohydrate for economic reasons; by NH₃The mass ratio of the ammonium monohydrate to the dialkylaminophenoxyacetic acid precipitator is preferably (0.01-0.3): 1, specifically 0.01:1, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1 or 0.3: 1; the temperature of the saponification reaction is preferably 15-35 ℃, and specifically can be 25 ℃ (room temperature); the time of the saponification reaction is preferably 10-60 min, and specifically may be 10min, 20min, 30min, 40min, 50min or 60 min. And obtaining the saponification precipitator after the saponification is finished.

In the enrichment method provided by the invention, after the saponification precipitator is obtained, the saponification precipitator is mixed with the feed liquid containing rare earth ions. The rare earth ions contained in the feed liquid include but are not limited to one or more of lanthanum ions, cerium ions, praseodymium ions, neodymium ions, samarium ions, europium ions, gadolinium ions, terbium ions, dysprosium ions, holmium ions, erbium ions, thulium ions, ytterbium ions, lutetium ions, scandium ions and yttrium ions; the total concentration of rare earth ions in the feed liquid is preferably 0.05-50 g/L, and specifically can be 0.05g/L, 1g/L, 2g/L, 2.3g/L, 3g/L, 5g/L, 10g/L, 15g/L, 20g/L, 25g/L, 30g/L, 35g/L, 40g/L, 45g/L or 50 g/L; the pH value of the feed liquid is preferably 5-7, and specifically can be 5, 5.5, 6, 6.5 or 7; the dosage ratio of the saponification precipitating agent to the feed liquid calculated by the dialkyl amino phenoxy acetic acid precipitating agent is preferably 33.5 g: (0.5-5) L, specifically 33.5 g: 0.5L, 33.5 g: 1L, 33.5 g: 1.5L, 33.5 g: 2L, 33.5 g: 2.5L, 33.5 g: 3L, 33.5 g: 3.5L, 33.5 g: 4L, 33.5 g: 4.5L or 33.5 g: 5L; the mixing temperature is preferably 15-35 ℃, and specifically can be 25 ℃ (room temperature); the mixing time is preferably 1-10 min, and specifically can be 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min or 10 min. And after the mixing is finished, carrying out solid-liquid separation to obtain a precipitate enriched with rare earth ions.

In the enrichment method provided by the invention, after the precipitate is obtained, the precipitate is eluted by using an inorganic acid solution. Wherein the acid in the inorganic acid solution includes but is not limited to one or more of hydrochloric acid, nitric acid and sulfuric acid; the concentration of the inorganic acid solution is preferably 0.5-12 mol/L, and specifically can be 0.5mol/L, 1mol/L, 2mol/L, 4mol/L, 6mol/L, 8mol/L, 10mol/L and 12 mol/L; the temperature of the elution is preferably 50-130 ℃, and specifically can be 50 ℃, 80 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃ or 130 ℃. In the elution process, the rare earth ions in the precipitate gradually enter into the acid liquor, and finally the rare earth enrichment solution and the regenerated dialkylaminophenoxyacetic acid precipitant are obtained.

The enrichment method provided by the invention enriches the rare earth ions in the feed liquid by using the saponified precipitator, has the advantages of short precipitation period, high enrichment rate, realization of the reuse of the precipitator and very good market prospect.

The invention also provides a saponification precipitating agent which has a chemical structure shown in a formula (II):

wherein R1 and R2 are independently selected from C₆～C₁₂Alkyl groups of (a); m is the residue remaining after removal of-OH from the hydroxide, including but not limited to NH₄ ⁺。

The saponification precipitating agent provided by the invention is a saponification product of a dialkyl amino phenoxyacetic acid precipitating agent with a structure shown in a formula (II), can be used for precipitating and enriching rare earth ions in rare earth-containing feed liquid, and has a very good market application prospect.

For the sake of clarity, the following examples are given in detail.

In the following examples and comparative examples, characterization was performed by the method for chemical analysis of rare earth metals and compounds thereof-determination of total amount of rare earth GB/T14635-. The precipitation rate P, the elution rate St and the total enrichment rate E (total) are calculated as follows: the concentrations of the rare earth ions in the water phase before and after precipitation are respectively C0 and C1, and the volumes are respectively V0 and V1; assuming that the concentration and volume of the rare earth ions in the water phase after elution are Cst and Vst respectively, then:

precipitation rate:

elution rate:

the total enrichment ratio is as follows:

example 1

The precipitator is 4-N, N-dihexylamino phenoxyacetic acid, namely, R1 is hexyl and R2 is hexyl in the formula (I), and the chemical structure of the precipitator is shown in the formula (I-1):

the preparation method of the 4-N, N-dihexylamino phenoxyacetic acid comprises the following steps:

a three-neck flask is filled with 0.1mol of p-nitrophenol, 100mL of a mixed solvent of ethanol and water in a volume ratio of 1:1, 0.1mol of sodium hydroxide is added, and the mixture is stirred and dissolved. Then 0.15mol of sodium chloroacetate and 0.2g of KI are added, the mixture is heated to 110 ℃, and the condensation reflux reaction is carried out for 0.5 h. After the reaction is finished, cooling to room temperature, evaporating the solvent, and washing with water to obtain the p-nitrophenoxyacetate.

And mixing the p-nitrophenyloxy acetate, 5mg of a commercially available 10 wt.% Pd/C catalyst and 100mL of an ethanol solvent, controlling the reaction temperature to be 70 ℃, circularly introducing hydrogen, reacting for 4 hours, cooling to room temperature, performing solid-liquid separation, and performing rotary evaporation to remove the ethanol solvent to obtain the p-aminophenoxyacetate.

Mixing p-aminophenoxy carboxylate, 0.1mol of sodium hydroxide, 0.2mol of 1-bromohexane and 100mL of ethanol solvent, controlling the reaction temperature at 75 ℃, reacting for 6 hours, cooling to room temperature after the reaction is finished, acidifying with inorganic acid, then removing the ethanol solvent by rotary evaporation, washing with water, and drying to obtain the 4-N, N-dihexylamino phenoxyacetic acid precipitator.

The results of acid-base titration and nuclear magnetic resonance instrument characterization show that: the purity of the 4-N, N-dihexylamino phenoxyacetic acid prepared by the embodiment is more than 95%, and the total preparation yield is more than 90%.

The rare earth enrichment steps are as follows:

1) and (3) saponification of a precipitator: diluting 25 wt.% of commercial ammonia water 6.8g to 25mL with deionized water, mixing with 33.5g of 4-N, N-dihexylamino phenoxyacetic acid at room temperature, stirring and reacting for 30min to obtain a saponification precipitant.

2) Precipitation reaction: taking 2.0L of rare earth feed liquid, wherein the total rare earth content is 2.3g/L, and the mass ratio (calculated by oxides) of each rare earth element is 27.5 percent of La, 2.5 percent of Ce, 5.86 percent of Pr, 21.7 percent of Nd, 5.12 percent of Sm, 0.35 percent of Eu, 4.76 percent of Gd, 0.7 percent of Tb, 3.77 percent of Dy, 0.63 percent of Ho, 1.98 percent of Er, 0.29 percent of Tm, 1.79 percent of Yb, 0.26 percent of Lu and 22.9 percent of Y. Adjusting pH to 6, adding saponification precipitant, stirring rapidly for 5min, precipitating completely, and performing solid-liquid separation to obtain solid precipitate.

3) And (3) elution: eluting the solid precipitate with 6mol/L hydrochloric acid at 50 deg.C to make rare earth enter into acid solution, and regenerating precipitant.

The result shows that the time of the rare earth precipitation for complete sedimentation is 5min, the precipitation rate of the rare earth obtained by the precipitation reaction is 98.2 percent, the elution rate in the elution process is 95.8 percent, and the total enrichment rate of the rare earth is 94.0 percent; the residual amount of precipitant in the solution was 10.3 ppm.

Example 2

The precipitator is 4-N, N-dioctyl amino phenoxyacetic acid, namely, R1 is octyl in the formula (I), R2 is octyl, and the chemical structure is specifically shown in the formula (I-2):

4-N, N-Dioctylaminophenoxyacetic acid was prepared according to example 1, except that the alkylating agent used was 1-bromooctane.

Acid-base titration and nuclear magnetic resonance characterization are carried out, and the results show that: the purity of the 4-N, N-dioctyl amino phenoxyacetic acid prepared by the embodiment is more than 95 percent, and the total preparation yield is more than 87 percent.

The rare earth enrichment step was performed in accordance with example 1, except that the amount of the 4-N, N-dioctylaminophenoxyacetic acid precipitant was 39.1g and the elution temperature was 80 ℃.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 99.0 percent, the elution rate in the elution process is 96.8 percent, and the total enrichment rate of the rare earth is 95.8 percent; the residual amount of precipitant in the solution was 8.6 ppm.

Example 3

The precipitator is 4- (N-dodecyl-N-nonyl amino) phenoxyacetic acid, namely, in the formula (I), R1 is dodecyl, R2 is nonyl, and the chemical structure of the precipitator is shown as the formula (I-3):

4- (N-dodecyl-N-nonylamino) phenoxyacetic acid was prepared according to the method described in example 1, except that the alkylating agents used were 1-bromononane and 1-bromododecane, in a molar ratio of 1:1.

Acid-base titration and nuclear magnetic resonance characterization are carried out, and the results show that: the purity of the 4- (N-dodecyl-N-nonyl amino) phenoxyacetic acid prepared by the embodiment is more than 95 percent, and the total preparation yield is more than 85 percent.

The rare earth enrichment step was performed in accordance with example 1, except that the amount of the 4- (N-dodecyl-N-nonylamino) phenoxyacetic acid precipitant was 46.1g and the elution temperature was 100 ℃.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 99.5 percent, the elution rate in the elution process is 97.7 percent, and the total enrichment rate of the rare earth is 97.4 percent; the residual amount of precipitant in the solution was 7.5 ppm.

Example 4

The precipitator is 4-N, N-didodecyl amino phenoxyacetic acid, namely, R1 is dodecyl in formula (I), R2 is dodecyl, and the chemical structure is specifically shown in formula (I-4):

4-N, N-Didodecyl amino phenoxy acetic acid was prepared according to example 1, except that the alkylating agent used was 1-bromododecane.

Acid-base titration and nuclear magnetic resonance characterization are carried out, and the results show that: the purity of the 4-N, N-didodecyl amino phenoxy acetic acid prepared in this example is more than 94%, and the total preparation yield is more than 85%.

The rare earth enrichment step was performed in accordance with example 1, except that the amount of the 4-N, N-didodecyl aminophenoxyacetic acid precipitant was 50.4g and the elution temperature was 130 ℃.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 97.0 percent, the elution rate in the elution process is 98.1 percent, and the total enrichment rate of the rare earth is 95.2 percent; the residual amount of precipitant in the solution was 3.2 ppm.

Example 5

Rare earth enrichment was performed using 4-N, N-dihexylamino phenoxyacetic acid prepared in example 1 as a precipitant, and the specific rare earth enrichment procedure was as described in example 1 except that the amount of commercially available ammonia water was adjusted to 40.2 g.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 99.4 percent, the elution rate in the elution process is 96.2 percent, and the total enrichment rate of the rare earth is 95.6 percent; the residual amount of precipitant in the solution was 15.7 ppm.

Example 6

The 4-N, N-dihexylamino phenoxyacetic acid prepared in the example 1 is used as a precipitator for rare earth enrichment, and the specific rare earth enrichment step refers to the example 1, and is different in that the pH value of the rare earth feed liquid is adjusted to 5.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 97.8 percent, the elution rate in the elution process is 96.0 percent, and the total enrichment rate of the rare earth is 93.9 percent; the residual amount of precipitant in the solution was 9.8 ppm.

Example 7

The 4-N, N-dihexylamino phenoxyacetic acid prepared in the example 1 is used as a precipitator for rare earth enrichment, and the specific rare earth enrichment step refers to the example 1, and is different in that the pH value of the rare earth feed liquid is adjusted to 7.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 98.6 percent, the elution rate in the elution process is 96.7 percent, and the total enrichment rate of the rare earth is 95.4 percent; the residual amount of precipitant in the solution was 10.5 ppm.

Example 8

Rare earth enrichment is carried out by adopting the 4-N, N-dihexylamino phenoxyacetic acid prepared in the example 1 as a precipitator, and the specific rare earth enrichment step refers to the example 1, and the difference is that the concentration of hydrochloric acid used for elution is adjusted to be 0.5 mol/L.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 98.2 percent, the elution rate in the elution process is 90.3 percent, and the total enrichment rate of the rare earth is 88.7 percent; the residual amount of precipitant in the solution was 10.3 ppm.

Example 9

Rare earth enrichment is carried out by adopting the 4-N, N-dihexylamino phenoxyacetic acid prepared in the example 1 as a precipitator, and the specific rare earth enrichment step refers to the example 1, and the difference is that the concentration of hydrochloric acid used for elution is adjusted to be 12 mol/L.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 98.2 percent, the elution rate in the elution process is 99.8 percent, and the total enrichment rate of the rare earth is 98 percent; the residual amount of precipitant in the solution was 10.3 ppm.

Example 10

The 4-N, N-dihexylamino phenoxyacetic acid prepared in the example 1 is used as a precipitator to carry out rare earth enrichment, and the specific rare earth enrichment step refers to the example 1, wherein the difference is that the elution temperature is adjusted to be 100 ℃.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 98.2 percent, the elution rate in the elution process is 94.6 percent, and the total enrichment rate of the rare earth is 92.8 percent; the residual amount of precipitant in the solution was 10.3 ppm.

Example 11

The 4-N, N-dihexylamino phenoxyacetic acid prepared in the example 1 is used as a precipitator to carry out rare earth enrichment, and the specific rare earth enrichment step refers to the example 1, which is different in that the elution temperature is adjusted to 130 ℃.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 98.2 percent, the elution rate in the elution process is 96.2 percent, and the total enrichment rate of the rare earth is 94.5 percent; the residual amount of precipitant in the solution was 10.3 ppm.

Comparative example 1

Taking the typical industrial precipitant ammonium bicarbonate as a reference, the rare earth enrichment steps are as follows:

precipitation reaction: taking 2.0L of rare earth feed liquid, wherein the total rare earth content is 2.3g/L, the mass proportion of each rare earth element is the same as that in example 1, adjusting the pH to be 6, adding 7.9g of ammonium bicarbonate solid, stirring, and carrying out solid-liquid separation after complete precipitation reaction to obtain solid precipitate.

And (3) elution: and eluting the rare earth precipitate by using 6mol/L hydrochloric acid solution to make the rare earth enter the hydrochloric acid solution.

The results show that in the present example, the time for the rare earth precipitation to completely settle is 30min, the solid-liquid separation is difficult, and the precipitation rate of the rare earth is 96.5%.

Comparative example 2

Rare earth enrichment was performed using 4-N, N-dihexylamino phenoxyacetic acid prepared in example 1 as a precipitant, and the specific rare earth enrichment procedure was as described in example 1 except that the amount of commercially available ammonia water was adjusted to 0.34 g.

The results show that the precipitation rate of the rare earth obtained by the precipitation reaction is 24.5 percent, the elution rate in the elution process is 99.7 percent, and the total enrichment rate of the rare earth is 24.4 percent; the residual amount of precipitant in the solution was 13.4 ppm.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.