A rare earth extractant and its application method

Abstract

The present invention belongs to the technical field of mineral extraction. More specifically, it relates to a rare earth extractant and its application method. The rare earth extractant of the present invention comprises raw materials in the following parts by weight: 30 - 40 parts of an organic extractant, 70 - 75 parts of a diluent, 6 - 8 parts of an interfacial stabilizer, and 5 - 10% of dioxane based on the mass of the organic extractant; wherein, the organic extractant is selected from any one of: 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester, bis(2-ethylhexyl) phosphate, naphthenic acid, and bis(2,4,4-trimethylpentyl) phosphonic acid; the diluent is composed of kerosene and palm oil mixed in a volume ratio of 1:1; the interfacial stabilizer is compounded from a non-ionic surfactant and gelatin in a mass ratio of 1:0.8 - 1.2; wherein, the gelatin selected is gelatin with an isoelectric point of 7.0; when the rare earth extractant is used, the pH of the aqueous phase is adjusted to below 6.6.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral extraction. More specifically, it relates to a rare earth extractant and its application method. Background Art

[0002] Due to the influence of the "lanthanide contraction" effect, rare earth elements have extremely similar properties, making their separation and purification difficult. After the rare earth ore is processed, a rare earth-containing leaching solution can be obtained, and then various classical methods can be used for separation. These methods mainly include fractional crystallization and precipitation methods, ion exchange and adsorption methods, solvent extraction methods, extraction chromatography methods, and liquid membrane separation methods, etc.

[0003] The solvent extraction method is the mainstream technology for the separation and enrichment of rare earth elements. Its principle is to utilize the solubility difference of rare earth ions in two immiscible solvents to achieve extraction. Compared with solid-liquid extraction, liquid-liquid extraction is widely used in industry due to its simple operation. With the in-depth research, a variety of high-efficiency extractants have been discovered and gradually replaced traditional extractants. At present, although the solvent extraction method has the advantages of high efficiency, continuous production and large processing capacity and has been widely used in the separation of rare earth elements, it still faces many problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that for the extraction method of rare earth elements, especially the liquid-liquid extraction method, although the operation is simple, there is still a bottleneck when the extraction effect needs to be further improved during the extraction process. In view of the existence of the above technical problems, the present invention provides a rare earth extractant and its application method.

[0005] The purpose of the present invention is to provide a rare earth extractant.

[0006] Another purpose of the present invention is to provide an application method of a rare earth extractant.

[0007] The above objects of the present invention are achieved by the following technical solutions:

[0008] A rare earth extractant, comprising the following raw materials in parts by weight: 30-40 parts of an organic extractant, 70-75 parts of a diluent, and 6-8 parts of an interface stabilizer;

[0009] Wherein, the organic extractant is selected from any one of: 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester, bis(2-ethylhexyl) phosphate, naphthenic acid, bis(2,4,4-trimethylpentyl) phosphonic acid;

[0010] The diluent is composed of kerosene and palm oil mixed in a volume ratio of 1:1;

[0011] The interface stabilizer is compounded from a non-ionic surfactant and gelatin in a mass ratio of 1:0.8-1.2;

[0012] Among them, the gelatin selected is gelatin with an isoelectric point of 7.0;

[0013] When the rare earth extractant is used, the extraction temperature is 35 - 45 °C, and the pH of the aqueous phase is adjusted to below 6.6.

[0014] Furthermore, the non-ionic surfactant is selected from any one of Span 80, Span 60, Span 40, and Span 20.

[0015] Furthermore, in the rare earth extractant, 5 - 10% of the mass of the organic extractant of dioxane is also included.

[0016] An application method of a rare earth extractant, the specific application steps include:

[0017] Preparation of the organic phase:

[0018] The diluent is divided into two equal parts. One part is stirred and mixed with the organic extractant to obtain a diluted extractant; the other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion;

[0019] Saponification is carried out on the diluted extractant by adding a sodium hydroxide solution to obtain a saponified organic phase;

[0020] The interfacial stabilizer dispersion is added to the saponified organic phase and stirred evenly to obtain the organic phase;

[0021] Preparation of the aqueous phase:

[0022] The pH of the solution containing rare earth ions to be extracted is adjusted to below 6.6 to obtain the aqueous phase;

[0023] Extraction:

[0024] After mixing the organic phase and the aqueous phase, stirring extraction is carried out at a temperature of 35 - 45 °C, and then standing for stratification to complete the extraction.

[0025] Furthermore, the preparation of the organic phase also includes:

[0026] The diluent is divided into two equal parts. One part is stirred and mixed with the organic extractant and 5 - 10% of the mass of the organic extractant of dioxane is added to obtain a diluted extractant; the other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion;

[0027] Saponification is carried out on the diluted extractant by adding a sodium hydroxide solution with a concentration of 6 - 8 mol / L to obtain a saponified organic phase;

[0028] Among them, the dosage of the sodium hydroxide solution is 50 - 60% of the mass of the organic extractant;

[0029] Add the interfacial stabilizer dispersion to the saponified organic phase and stir evenly to obtain the organic phase.

[0030] Furthermore, the preparation of the organic phase further includes:

[0031] Divide the diluent into two equal parts. One part is stirred and mixed with the organic extractant to obtain a diluted extractant; the other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion.

[0032] Add a sodium hydroxide solution with a concentration of 6 - 8 mol / L to the diluted extractant for saponification to obtain the saponified organic phase.

[0033] Among them, the dosage of the sodium hydroxide solution is 50 - 60% of the mass of the organic extractant.

[0034] Among them, the preparation method of the interfacial stabilizer includes:

[0035] Dissolve gelatin in water to prepare a gelatin solution with a mass fraction of 10 - 15%.

[0036] Mix the gelatin solution and the non - ionic surfactant evenly to obtain the interfacial stabilizer.

[0037] Add the interfacial stabilizer dispersion to the saponified organic phase and stir evenly to obtain the organic phase.

[0038] Furthermore, the gelatin is selected from low - molecular - weight gelatin with an average molecular weight of 5000 - 15000.

[0039] Furthermore, the rare - earth ions are selected from any one of lanthanum ions, cerium ions, praseodymium ions, neodymium ions, and samarium ions.

[0040] The beneficial effects of the present invention include:

[0041] (1)For the extraction of rare earth ions by liquid-liquid extraction, the inventor found in the actual operation process that emulsification would occur. The occurrence of emulsification not only affects the extraction efficiency but also causes certain environmental pollution. Through in-depth research, it is found that the occurrence of emulsification is caused by the properties of the organic phase or the aqueous phase during the extraction process and may also be related to the control of operating conditions. Based on this, the inventor adds an interfacial stabilizer to the organic phase of the extraction to improve the stability of the organic phase system and prevent emulsification during the extraction process. Specifically, by using a non-ionic surfactant, it provides high interfacial activity and has a large interfacial adsorption capacity. Therefore, it can improve the interfacial stability of the organic phase and thus reduce the occurrence of emulsification. However, during the extraction process, in order to improve the extraction efficiency, an appropriate extraction temperature needs to be selected. However, the adjustment of temperature will cause changes in the stability of the extraction system. Based on this, gelatin is added to the interfacial stabilizer, and gelatin with an isoelectric point of 7.0 is selected. During the extraction process, the pH of the aqueous phase is controlled below 6.6. In this way, the amino groups in the gelatin molecular structure can be protonated, and due to the electrostatic repulsion caused by carrying the same positive charge, the gelatin molecular chains can fully stretch on the liquid film surface, strengthening the stability of the organic phase and further reducing the problem of decreased stability caused by changes in operating conditions, such as extraction temperature, during the extraction process, ensuring the extraction effect.

[0042] (2)Furthermore, by adding dioxane to the system and controlling its addition amount within a suitable range, it plays a role in diluting the organic phase and adjusting the specific gravity of the organic phase to a reasonable range, thereby adjusting the interfacial tension between the aqueous phase and the organic phase during the extraction process and reducing the possibility of emulsification. Detailed implementation mode

[0043] The following specific examples are used to further illustrate the present invention, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0044] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0045] Example 1

[0046] Preparation of rare earth extractant:

[0047] By weight, 30 parts of organic extractant, 70 parts of diluent, and 6 parts of interfacial stabilizer are taken in sequence; and dioxane accounting for 5% of the mass of the organic extractant;

[0048] Among them, the organic extractant is selected from: mono-2-ethylhexyl 2-ethylhexylphosphate;

[0049] The diluent is composed of kerosene and palm oil mixed at a volume ratio of 1:1;

[0050] The interfacial stabilizer is prepared by compounding a non-ionic surfactant and gelatin at a mass ratio of 1:0.8;

[0051] Among them, the gelatin selected is gelatin with an isoelectric point of 7.0;

[0052] The gelatin is selected from low-molecular-weight gelatin with an average molecular weight of 5000;

[0053] Specifically, when preparing the interfacial stabilizer, it includes:

[0054] Dissolve the gelatin in water to prepare a 10% gelatin solution by mass;

[0055] Mix the gelatin solution and the non-ionic surfactant evenly to obtain the interfacial stabilizer;

[0056] The non-ionic surfactant is selected from Span 80;

[0057] Preparation of the organic phase:

[0058] Divide the diluent into two equal parts. Mix one part with the organic extractant and stir, then add dioxane to obtain the diluted extractant;

[0059] Mix the other part with the interfacial stabilizer and stir to obtain the interfacial stabilizer dispersion;

[0060] Add a 6 mol / L sodium hydroxide solution to the diluted extractant for saponification to obtain the saponified organic phase;

[0061] Among them, the dosage of the sodium hydroxide solution is 50% of the mass of the organic extractant;

[0062] Preparation of the aqueous phase:

[0063] Mix rare earth oxide and 30% concentrated hydrochloric acid at a mass ratio of 1:6, then under the conditions of a temperature of 70 °C and a stirring speed of 300 r / min, heat and stir for 2 h, then add deionized water 10 times the mass of the concentrated hydrochloric acid, and then adjust the pH to 6.6 to obtain the aqueous phase containing rare earth ions;

[0064] The rare earth ions are selected from: lanthanum ions;

[0065] Extraction:

[0066] Mix the organic phase and the aqueous phase at a volume ratio of 1:1, then under the conditions of a temperature of 35 °C and a stirring speed of 80 r / min, stir and extract for 20 min, then let it stand for 2 h to separate layers, and separate the aqueous phase and the organic phase, thus completing the extraction.

[0067] Example 2

[0068] Preparation of rare earth extractant:

[0069] By weight, 35 parts of organic extractant, 72 parts of diluent and 7 parts of interfacial stabilizer are taken in sequence; and dioxane accounting for 8% of the mass of the organic extractant;

[0070] Among them, the organic extractant is selected from: bis(2-ethylhexyl) phosphate;

[0071] The diluent is composed of kerosene and palm oil mixed in a volume ratio of 1:1;

[0072] The interfacial stabilizer is prepared by compounding a non-ionic surfactant and gelatin in a mass ratio of 1:1;

[0073] Among them, the gelatin with an isoelectric point of 7.0 is selected;

[0074] The gelatin is selected from low molecular weight gelatin with an average molecular weight of 12,000;

[0075] Specifically, when preparing the interfacial stabilizer, it includes:

[0076] Dissolve gelatin in water to prepare a 12% gelatin solution by mass fraction;

[0077] Mix the gelatin solution and the non-ionic surfactant evenly to obtain the interfacial stabilizer;

[0078] The non-ionic surfactant is selected from Span 60;

[0079] Preparation of organic phase:

[0080] Divide the diluent into two equal parts. One part is stirred and mixed with the organic extractant, and dioxane is added to obtain a diluted extractant;

[0081] The other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion;

[0082] Add a sodium hydroxide solution with a concentration of 7 mol / L to the diluted extractant for saponification to obtain a saponified organic phase;

[0083] Among them, the dosage of the sodium hydroxide solution is 55% of the mass of the organic extractant;

[0084] Preparation of aqueous phase:

[0085] Mix rare earth oxides and concentrated hydrochloric acid with a mass fraction of 32% at a mass ratio of 1:6. Then, under the conditions of a temperature of 75 °C and a stirring speed of 400 r / min, heat and stir the mixture for 3 h. Next, add deionized water that is 10 times the mass of the concentrated hydrochloric acid, and then adjust the pH to 6.4 to obtain an aqueous phase containing rare earth ions.

[0086] The rare earth ions are selected from: cerium ions;

[0087] Extraction:

[0088] Mix the organic phase and the aqueous phase at a volume ratio of 1:1. Then, under the conditions of a temperature of 40 °C and a stirring speed of 90 r / min, stir and extract for 25 min, and then let it stand for 2.5 h to separate layers. Separate the aqueous phase and the organic phase to complete the extraction.

[0089] Example 3

[0090] Preparation of rare earth extractant:

[0091] By weight, successively take 40 parts of organic extractant, 75 parts of diluent, and 8 parts of interfacial stabilizer; and dioxane that is 10% of the mass of the organic extractant.

[0092] Among them, the organic extractant is selected from: naphthenic acid;

[0093] The diluent is composed of kerosene and palm oil mixed at a volume ratio of 1:1;

[0094] The interfacial stabilizer is compounded from a non-ionic surfactant and gelatin at a mass ratio of 1:1.2;

[0095] Among them, the gelatin selected has an isoelectric point of 7.0;

[0096] The gelatin is selected from low molecular weight gelatin with an average molecular weight of 15,000;

[0097] Specifically, when preparing the interfacial stabilizer, it includes:

[0098] Dissolve gelatin in water to prepare a gelatin solution with a mass fraction of 15%;

[0099] Mix the gelatin solution and the non-ionic surfactant evenly to obtain the interfacial stabilizer;

[0100] The non-ionic surfactant is selected from Span 40;

[0101] Preparation of organic phase:

[0102] Divide the diluent into two equal parts. Mix one part with the organic extractant and stir, and add dioxane to obtain a diluted extractant;

[0103] Mix with another interfacial stabilizer and stir to obtain an interfacial stabilizer dispersion;

[0104] Add a sodium hydroxide solution with a concentration of 8 mol / L to the diluted extractant for saponification to obtain a saponified organic phase;

[0105] Among them, the dosage of the sodium hydroxide solution is 60% of the mass of the organic extractant;

[0106] Preparation of the aqueous phase:

[0107] Mix rare earth oxide and concentrated hydrochloric acid with a mass fraction of 35% according to a mass ratio of 1:6, and then under the conditions of a temperature of 80 °C and a stirring speed of 500 r / min, heat and stir for 4 h, then add deionized water 10 times the mass of the concentrated hydrochloric acid, and then adjust the pH to 6.2 to obtain an aqueous phase containing rare earth ions;

[0108] The rare earth ions are selected from: praseodymium ions;

[0109] Extraction:

[0110] Mix the organic phase and the aqueous phase at a volume ratio of 1:1, and then stir and extract for 30 min under the conditions of a temperature of 45 °C and a stirring speed of 100 r / min, then let it stand for 3 h to separate layers, and separate the aqueous phase and the organic phase to complete the extraction.

[0111] Example 4

[0112] Compared with Example 1, the difference in this example is that dioxane is not added, and the other conditions remain unchanged.

[0113] Comparative Example 1

[0114] Compared with Example 1, the difference in this comparative example is that cyclodextrin of equal mass is used to replace gelatin, and the other conditions remain unchanged.

[0115] Comparative Example 2

[0116] Compared with Example 1, the difference in this comparative example is that gelatin is not added, and the other conditions remain unchanged.

[0117] Comparative Example 3

[0118] Compared with Example 1, the difference in this comparative example is that the interfacial stabilizer is not added, and the other conditions remain unchanged.

[0119] Test the extraction results of the above examples and comparative examples. The specific test methods and test results are as follows:

[0120] After the extraction is completed, collect the aqueous phase below. Under the condition of 8000 r / min, centrifuge for 25 min, and then use an ultraviolet spectrophotometer to measure the concentration of rare earth ions in the aqueous phase; then calculate the change in ion concentration before and after extraction, and use it as the extraction rate in turn.

[0121] In addition, collect the raffinate. Under the condition of 5000 r / min, centrifuge for 10 min, collect the supernatant below, and measure the oil content in it with an infrared oil analyzer.

[0122] The detailed test results are shown in Table 1.

[0123] Table 1: Analysis of Extraction Results

[0124]

[0125] It can be seen from the test results in Table 1 that the extractant and extraction method adopted in the present invention can effectively extract rare earth metal ions.

[0126] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A rare earth extractant, characterized in that: The method comprises the following raw materials in parts by weight: 30-40 parts of an organic extractant, 70-75 parts of a diluent and 6-8 parts of an interfacial stabilizer; Wherein, the organic extractant is selected from any one of: 2-ethylhexyl phosphate mono-2-ethylhexyl ester, di(2-ethylhexyl) phosphate, cyclohexane acid, and bis(2,4,4-trimethylpentyl)phosphonic acid; The diluent is a mixture of kerosene and palm oil in a volume ratio of 1:1; The interfacial stabilizer is prepared by compounding a nonionic surfactant and gelatin in a mass ratio of 1:0.8-1.2; Wherein, the gelatin is selected to have an isoelectric point of 7.0; When the rare earth extractant is used, the extraction temperature is 35-45°C, and the pH of the aqueous phase is adjusted to below 6.6; The rare earth extractant also includes 5-10% of the mass of dioxane of the organic extractant.

2. A rare earth extractant according to claim 1, characterized in that: The nonionic surfactant is selected from any one of Span 80, Span 60, Span 40 and Span 20.

3. A method for using the rare earth extractant according to any one of claims 1 to 2, characterized in that: The specific application steps include: Preparation of organic phase: The diluent is divided into two equal parts, one of which is stirred and mixed with the organic extractant, and 5-10% of the mass of dioxane of the organic extractant is added to obtain a diluted extractant; the other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion; adding sodium hydroxide solution to the diluted extractant for saponification to obtain a saponified organic phase; Adding the interfacial stabilizer dispersion to the saponified organic phase and stirring evenly to obtain an organic phase; Preparation of water phase: The pH of the solution containing rare earth ions to be extracted is adjusted to below 6.6 to obtain an aqueous phase; extraction: After the organic phase and the aqueous phase are mixed, the extraction is stirred at a temperature of 35-45°C and allowed to stand to separate the layers. The extraction is completed.

4. The application method of a rare earth extractant according to claim 3, characterized in that: The preparation of the organic phase also includes: The diluent is divided into two equal parts, one of which is stirred and mixed with the organic extractant, and 5-10% of the mass of dioxane of the organic extractant is added to obtain a diluted extractant; the other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion; Adding a sodium hydroxide solution with a concentration of 6-8 mol / L to the diluted extractant for saponification to obtain a saponified organic phase; Wherein, the amount of the sodium hydroxide solution is 50-60% of the mass of the organic extractant; Add the interfacial stabilizer dispersion to the saponified organic phase and stir evenly to obtain an organic phase.

5. The application method of a rare earth extractant according to claim 4, characterized in that: The preparation of the organic phase also includes: The diluent is divided into two equal parts, one of which is stirred and mixed with the organic extractant, and 5-10% of the mass of dioxane of the organic extractant is added to obtain a diluted extractant; the other part is stirred and mixed with the interfacial stabilizer to obtain an interfacial stabilizer dispersion; Adding a sodium hydroxide solution with a concentration of 6-8 mol / L to the diluted extractant for saponification to obtain a saponified organic phase; Wherein, the amount of the sodium hydroxide solution is 50-60% of the mass of the organic extractant; Wherein, the preparation method of the interface stabilizer comprises: Dissolve gelatin in water to prepare a gelatin solution with a mass fraction of 10-15%; The gelatin solution and the nonionic surfactant are uniformly mixed to obtain an interfacial stabilizer; Add the interfacial stabilizer dispersion to the saponified organic phase and stir evenly to obtain an organic phase.

6. The application method of a rare earth extractant according to any one of claims 4 or 5, characterized in that: The gelatin is selected from low molecular weight gelatin with an average molecular weight of 5000-15000.

7. The application method of a rare earth extractant according to claim 3, characterized in that: The rare earth ion is selected from any one of lanthanum ion, cerium ion, praseodymium ion, neodymium ion and samarium ion.

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