A process for extracting and separating rare earth terbium, dysprosium and holmium oxides

Abstract

The invention belongs to the field of rare earth extraction and separation technology, and particularly relates to a process for extracting and separating rare earth terbium dysprosium holmium oxide, comprising the following steps: S1 grinding terbium dysprosium holmium oxide rich; S2 partially dissolving the particles obtained in step S1 to obtain rare earth liquid; S3 preparing a blank organic phase; S4 adding part of the blank organic phase into a container, adding the rare earth liquid for extraction; S5 adding terbium dysprosium holmium oxide particles rich in the aqueous phase obtained in step S4 to adjust to rare earth liquid, and continuing extraction; S6 adding terbium dysprosium holmium oxide particles rich in the aqueous phase obtained in step S5 to adjust to rare earth liquid, adding the blank organic phase obtained in step S3, and continuing extraction; S7 measuring the result. In the process of extracting and separating rare earths according to the invention, no alkali is used, and the aqueous phase can be used multiple times. The single-stage treatment technology without adding alkali is used to extract and separate rare earth oxides, which can significantly reduce the use of hydrochloric acid and liquid alkali, and has a significant effect on reducing economic costs and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth extraction and separation, and particularly relates to a process for extracting and separating rare earth terbium, dysprosium and holmium oxides. Background Art

[0002] Rare earths are important strategic resources. Due to their unique electronic structure and physical and chemical properties, rare earth elements play an irreplaceable role in many high-tech fields. The following are some of the main uses of rare earth elements, mainly the following uses:

[0003] 1. Permanent magnet material: Neodymium iron boron (NdFeB) is one of the strongest permanent magnet materials and is widely used in wind turbines, electric vehicle motors, audio equipment, hard disk drives, and various high-efficiency motors and sensors.

[0004] 2. Luminescent materials: Rare earth elements such as europium (Eu) and terbium (Tb) are used to manufacture phosphors for fluorescent lamps, LED lamps, and backlight sources for televisions and computer monitors to improve luminous efficiency and color quality.

[0005] 3. Catalyst: Cerium (Ce) is used as a catalyst for automobile exhaust purification, effectively reducing emissions; lanthanum (La), cerium, etc. can also be used as petroleum cracking catalysts to improve reaction efficiency.

[0006] 4. Glass and ceramics: Rare earth elements can be added to glass and ceramics to improve their optical properties, such as increasing transparency, reducing dispersion or imparting specific colors. They are commonly found in high-end eyeglass lenses, laser materials and precision ceramic products.

[0007] 5. Electronic products: Samarium (Sm), europium, etc. are used to manufacture various components of microwave communication equipment, mobile phones, tablet computers and other electronic products, such as magnetostrictive materials and high-frequency magnetic materials.

[0008] 6. Metallurgical industry: In the steel manufacturing industry, adding rare earths can refine grains, improve the toughness, heat resistance and corrosion resistance of alloys, such as the modification of light alloys such as magnesium, aluminum and titanium.

[0009] 7. Agriculture: A small amount of rare earth elements such as cerium and lanthanum are used as fertilizer additives to promote plant growth, enhance stress resistance, and improve crop yield and quality.

[0010] 8. Medical field: Gadolinium (Gd) is used as a contrast agent in magnetic resonance imaging (MRI) to improve image clarity; thulium (Tm), holmium (Ho), etc. are used in laser surgical instruments because they can efficiently absorb light energy of specific wavelengths.

[0011] 9. Battery technology: Some rare earth elements are used to increase the energy density and service life of batteries, especially in nickel-metal hydride batteries and some new battery technologies.

[0012] Therefore, the separation technology of rare earths has always attracted much attention. Rare earth extraction is the key process for the separation and purification of rare earth elements, which mainly involves chemical extraction. There are mainly the following methods:

[0013] 1. Solvent extraction: This is the most commonly used rare earth extraction method in industry. The basic principle is to use the difference in solubility of different rare earth elements in the organic phase (blank organic phase) and the aqueous phase for separation. Typical extraction systems include the use of phosphoric acid (such as P204, P507), amines (such as TBP, N235) or acidic phosphorus blank organic phase (such as D2EHPA). The process usually includes multiple cascade extraction and washing sections, and the separation effect is optimized by adjusting the pH value, salt concentration and blank organic phase type.

[0014] 2. Ion exchange method: Although ion exchange is more used for preliminary enrichment or purification of certain special rare earths, it can also be used as a form of extraction in some cases. This method uses solid ion exchange resins to selectively adsorb and desorb rare earth ions of different charge states in the solution to achieve separation.

[0015] 3. Liquid membrane extraction: This is a membrane separation technology based on the principle of solvent extraction. By dispersing the blank organic phase in the membrane phase to form a liquid membrane, the rare earth ions in the aqueous phase can selectively pass through the liquid membrane into the organic phase. Liquid membrane extraction has the characteristics of high efficiency, simple operation and easy continuous operation.

[0016] 4. Supercritical fluid extraction: Supercritical carbon dioxide is used as a blank organic phase. Due to its special physical properties (neither gas nor liquid), it can effectively dissolve certain substances. This method has advantages in environmental friendliness and selectivity, but it is not widely used in the field of rare earth extraction, mainly due to the limitations of cost and technical maturity.

[0017] 5. Bioextraction: Extraction using the adsorption and enrichment capabilities of microorganisms, plants or their extracts for specific rare earth elements. This is an environmentally friendly extraction method, but it is still in the laboratory research stage and has not yet been applied to industrial production on a large scale.

[0018] At present, most rare earth separation companies still use traditional extraction separation methods, but the traditional extraction method uses saponification technology to maintain extraction conditions, which consumes a lot of acid and alkali materials. The above traditional extraction methods have high feed costs and high wastewater treatment pressure, which is not conducive to the healthy and sustainable development of enterprises.

[0019] CN 111440946 B discloses a rare earth extraction method for realizing the recycling of magnesium bicarbonate. The rare earth extraction method of the present invention uses magnesium bicarbonate to saponify an acidic blank organic phase, and simultaneously recovers saponification wastewater and CO2 in the saponification process, and the obtained magnesium soap organic phase is subjected to rare earth saponification treatment with a rare earth feed liquid to realize the extraction of rare earths and obtain rare earth products, and the magnesium chloride wastewater generated in the rare earth saponification process is mixed with saponification wastewater and an amine blank organic phase, and the recovered CO2 is used for extraction-carbonization reaction to convert magnesium chloride into magnesium bicarbonate, which can be recycled for the saponification process of the acidic blank organic phase, realizing the closed-loop recycling of magnesium salts, greatly reducing the emission of salts in the rare earth extraction process, and having significant environmental benefits. However, it still involves a chemical reaction, and the three wastes are discharged in large quantities. Summary of the invention

[0020] The purpose of the present invention is to provide a process technology for extracting and separating rare earth terbium dysprosium holmium oxides, which greatly reduces the input of acid and alkali materials, so that the rare earth concentration of the loaded organic phase reaches the requirement of 0.15-0.2 mol / L, and ultimately achieves the purpose of saving resources, green environmental protection and sustainable development.

[0021] The present invention adopts the following technical solution:

[0022] A process for extracting and separating rare earth terbium, dysprosium and holmium oxides comprises the following steps:

[0023] S1 feeds the terbium-dysprosium-holmium-rich oxide into a grinder, grinds it into particles with a particle size of 2 μm to 10 μm, and sets it aside;

[0024] S2: dissolving the granules obtained in step S1 with hydrochloric acid, adjusting the pH value to about 1 and the total rare earth concentration to 1 mol / L, to obtain a rare earth liquid;

[0025] S3 prepares a blank organic phase, 2-ethylhexyl phosphate 2-ethylhexyl ester (P507), aviation kerosene and tetrabutyl urea in a volume ratio of 1:1:(0-1), and then adds a hydrochloric acid solution of 10% of the total volume, stirs and mixes evenly, and after static stratification, releases the aqueous phase to obtain a blank organic phase, wherein the hydrochloric acid solution contains an oxidant. The present invention adopts a preferred solvent combination, has high extraction efficiency, and has low solvent loss. In particular, after adding the tetrabutyl urea component, under the action of hydrochloric acid, the tetrabutyl urea and hydrochloric acid form a characteristic similar to a low eutectic solvent, which has a good extraction effect on the rare earth component oil;

[0026] S4: adding a portion of the blank organic phase into a container, and then adding 20% ​​of the volume of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remainder is the first organic phase;

[0027] S5: adding 10% of the mass of the terbium-dysprosium-holmium oxide particles dissolved in step S2 to the first aqueous phase obtained in step S4 to prepare a rare earth solution, adding the solution to the first organic phase, stirring for 60 minutes, separating the aqueous phase as the second aqueous phase, and the remainder as the second organic phase;

[0028] S6: adding 10% of the mass of the terbium-dysprosium-holmium oxide particles dissolved in step S2 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding part of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase into the third aqueous phase, and the remaining is the third organic phase, the amount of the blank organic phase added is the same as the amount of the blank organic phase added in step S4, and the third aqueous phase can be repeatedly recycled later;

[0029] S7 used hydrochloric acid back extraction and EDTA titration to determine the loading concentration of the second organic phase and the third organic phase, respectively. The measured results were 0.185-0.200 mol / L and 0.160-0.185 mol / L, respectively, which were in line with expectations.

[0030] Furthermore, the concentration of the hydrochloric acid solution in step S2 is 30-31 wt%.

[0031] Furthermore, in the step S2, the oxidant in the hydrochloric acid solution is at least one of hydrogen peroxide and percarbonic acid amide. By adding the oxide to the hydrochloric acid, the acidity and oxidizing properties can be utilized to accelerate the dissolution of the rare earth oxide, thereby improving the effective dissolution speed and efficiency.

[0032] Furthermore, the content of peroxidant in the hydrochloric acid solution in step S2 is 0-2 wt %.

[0033] Furthermore, in step S4, S5 or S6, the rare earth solution is added by micron-level spraying followed by addition of the organic phase.

[0034] Furthermore, the content of terbium, dysprosium and holmium oxide in step S1 is greater than 99%.

[0035] Furthermore, in step S3, the concentration of the hydrochloric acid solution is 30-31 wt%.

[0036] The present invention does not use alkali in the process of extracting and separating rare earths, and the water phase can be used multiple times. The single-stage treatment technology without adding alkali is used to extract and separate rare earth oxides, which can significantly reduce the use of hydrochloric acid and liquid alkali, and has a significant effect on reducing economic costs and protecting the environment. The raw materials used in the present invention are suitable for all rare earth total amount ≥ 99% enriched and pure materials. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with embodiments. The present invention is not limited to the embodiments. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0038] Example 1

[0039] A process for extracting and separating rare earth terbium, dysprosium and holmium oxides comprises the following steps:

[0040] S1: 50 g of terbium-dysprosium-holmium oxide with a content of 99.1% is fed into a grinder and ground into particles with a particle size of 2 μm to 10 μm for later use;

[0041] S2: dissolving 20 g of the particles obtained in step S1 in 31 wt % hydrochloric acid, adjusting the pH value to about 1 and the total rare earth concentration to 1 mol / L, to obtain a rare earth liquid;

[0042] S3 prepares a blank organic phase, mixes 500 ml of 2-ethylhexyl phosphate and 500 ml of aviation kerosene, then adds 100 ml of 31 wt% hydrochloric acid solution, stirs and mixes evenly, and after static separation, releases the aqueous phase to obtain a blank organic phase;

[0043] S4: adding 50 ml of the blank organic phase into a container, and then adding 10 ml of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remaining is the first organic phase;

[0044] S5: 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 in the first aqueous phase obtained in step S4 are adjusted to a rare earth solution, added to the first organic phase, stirred for 60 minutes, and the aqueous phase is separated as the second aqueous phase, and the remainder is the second organic phase;

[0045] S6: adding 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding 50 ml of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase as the third aqueous phase, and the remainder as the third organic phase;

[0046] S7 used hydrochloric acid back extraction and EDTA titration to determine the loading concentration of the second organic phase and the third organic phase, respectively. The measured results were 0.185 mol / L and 0.169 mol / L, which were in line with expectations.

[0047] Example 2

[0048] A process for extracting and separating rare earth terbium, dysprosium and holmium oxides comprises the following steps:

[0049] S1: 50 g of terbium-dysprosium-holmium oxide with a content of 99.2% is fed into a grinder and ground into particles with a particle size of 2 μm to 10 μm for later use;

[0050] S2: dissolving 20 g of the particles obtained in step S1 in 31 wt % hydrochloric acid, adjusting the pH value to about 1 and the total rare earth concentration to 1 mol / L, to obtain a rare earth liquid;

[0051] S3 prepares a blank organic phase, mixes 500 ml of 2-ethylhexyl phosphate, 500 ml of aviation kerosene, and 50 ml of tetrabutyl urea, then adds 105 ml of 31 wt% hydrochloric acid solution, stirs and mixes evenly, and after static separation, releases the aqueous phase to obtain a blank organic phase;

[0052] S4: adding 50 ml of the blank organic phase into a container, and then adding 10 ml of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remaining is the first organic phase;

[0053] S5: 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 in the first aqueous phase obtained in step S4 are adjusted to a rare earth solution, added to the first organic phase, stirred for 60 minutes, and the aqueous phase is separated as the second aqueous phase, and the remainder is the second organic phase;

[0054] S6: adding 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding 50 ml of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase as the third aqueous phase, and the remainder as the third organic phase;

[0055] S7 used hydrochloric acid back extraction and EDTA titration to determine the loading concentration of the second organic phase and the third organic phase, respectively. The measured results were 0.192 mol / L and 0.171 mol / L, which were in line with expectations.

[0056] Example 3

[0057] A process for extracting and separating rare earth terbium, dysprosium and holmium oxides comprises the following steps:

[0058] S1: 50 g of terbium-dysprosium-holmium oxide with a content of 99.2% is fed into a grinder and ground into particles with a particle size of 2 μm to 10 μm for later use;

[0059] S2: dissolving 20 g of the particles obtained in step S1 in 31 wt% hydrochloric acid, adjusting the pH value to about 1, and the total rare earth concentration to 1 mol / L, to obtain a rare earth solution, wherein the hydrogen peroxide content in the hydrochloric acid solution in step S2 is 1 wt%;

[0060] S3 prepares a blank organic phase, mixes 500 ml of 2-ethylhexyl phosphate, 500 ml of aviation kerosene, and 50 ml of tetrabutyl urea, then adds 105 ml of 31 wt% hydrochloric acid solution, stirs and mixes evenly, and after static separation, releases the aqueous phase to obtain a blank organic phase;

[0061] S4: adding 50 ml of the blank organic phase into a container, and then adding 10 ml of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remaining is the first organic phase;

[0062] S5: 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 in the first aqueous phase obtained in step S4 are adjusted to a rare earth solution, added to the first organic phase, stirred for 60 minutes, and the aqueous phase is separated as the second aqueous phase, and the remainder is the second organic phase;

[0063] S6: adding 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding 50 ml of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase as the third aqueous phase, and the remainder as the third organic phase;

[0064] S7 used hydrochloric acid back extraction and EDTA titration to determine the loading concentration of the second organic phase and the third organic phase, respectively. The measured results were 0.194 mol / L and 0.181 mol / L, which were in line with expectations.

[0065] Example 4

[0066] A process for extracting and separating rare earth terbium, dysprosium and holmium oxides comprises the following steps:

[0067] S1: 50 g of terbium-dysprosium-holmium oxide with a content of 99.2% is fed into a grinder and ground into particles with a particle size of 2 μm to 10 μm for later use;

[0068] S2: dissolving 20 g of the particles obtained in step S1 in 31 wt% hydrochloric acid, adjusting the pH value to about 1, and the total rare earth concentration to 1 mol / L, to obtain a rare earth liquid, wherein the content of percarbonic acid amide in the hydrochloric acid solution in step S2 is 0.5 wt%;

[0069] S3 prepares a blank organic phase, mixes 500 ml of 2-ethylhexyl phosphate, 500 ml of aviation kerosene, and 70 ml of tetrabutyl urea, then adds 107 ml of 31 wt% hydrochloric acid solution, stirs and mixes evenly, and after static separation, releases the aqueous phase to obtain a blank organic phase;

[0070] S4: adding 50 ml of the blank organic phase into a container, and then adding 10 ml of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remaining is the first organic phase;

[0071] S5: 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 in the first aqueous phase obtained in step S4 are adjusted to a rare earth solution, added to the first organic phase, stirred for 60 minutes, and the aqueous phase is separated as the second aqueous phase, and the remainder is the second organic phase;

[0072] S6: adding 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding 50 ml of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase as the third aqueous phase, and the remainder as the third organic phase;

[0073] S7 used hydrochloric acid back extraction and EDTA titration to determine the loading concentration of the second organic phase and the third organic phase, respectively. The measured results were 0.196 mol / L and 0.183 mol / L, which were in line with expectations.

[0074] Example 5

[0075] A process for extracting and separating rare earth terbium, dysprosium and holmium oxides comprises the following steps:

[0076] S1: 50 g of terbium-dysprosium-holmium oxide with a content of 99.2% is fed into a grinder and ground into particles with a particle size of 2 μm to 10 μm for later use;

[0077] S2: dissolving 20 g of the particles obtained in step S1 in 31 wt% hydrochloric acid, adjusting the pH value to about 1, and the total rare earth concentration to 1 mol / L, to obtain a rare earth liquid, wherein the content of percarbonic acid amide in the hydrochloric acid solution in step S2 is 0.5 wt%;

[0078] S3 prepares a blank organic phase, mixes 500 ml of 2-ethylhexyl phosphate, 500 ml of aviation kerosene, and 70 ml of tetrabutyl urea, then adds 107 ml of 31 wt% hydrochloric acid solution, stirs and mixes evenly, and after static separation, releases the aqueous phase to obtain a blank organic phase;

[0079] S4: adding 50 ml of the blank organic phase into a container, and then adding 10 ml of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remaining is the first organic phase;

[0080] S5: 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 in the first aqueous phase obtained in step S4 are adjusted to a rare earth solution, added to the first organic phase, stirred for 60 minutes, and the aqueous phase is separated as the second aqueous phase, and the remainder is the second organic phase;

[0081] S6: adding 2 g of the terbium-dysprosium-holmium oxide particles obtained in step S1 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding 50 ml of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase as the third aqueous phase, and the remainder as the third organic phase;

[0082] S7 used hydrochloric acid back extraction and EDTA titration to determine the loading concentration of the second organic phase and the third organic phase, respectively. The measured results were 0.199 mol / L and 0.185 mol / L, which were in line with expectations.

[0083] In step S4, S5 or S6 of Example 5, the rare earth solution is added by micron-level spraying followed by addition of the organic phase.

[0084] The above experimental data show that the addition of tetrabutyl urea, as well as appropriately increasing the content of tetrabutyl urea, adding rare earth liquid by micron-level spraying, and adding oxides to the hydrochloric acid solution can all improve the extraction and separation efficiency of rare earths.

Claims

1. A process for extracting and separating rare earth terbium, dysprosium and holmium oxides, characterized in that: The following steps are involved: S1 feeds the terbium-dysprosium-holmium oxide into a grinder, grinds it into particles with a particle size of 2μm~10μm, and sets it aside; S2. Dissolve the granules obtained in step S1 with hydrochloric acid, adjust the pH value to 1, and adjust the total rare earth concentration to 1 mol / L to obtain a rare earth liquid; S3: preparing a blank organic phase, mixing 2-ethylhexyl phosphate, aviation kerosene and tetrabutyl urea at a volume ratio of 1:1:1, then adding a hydrochloric acid solution of 10% of the total volume, stirring and mixing, and after standing and stratifying, releasing the aqueous phase to obtain a blank organic phase, wherein the hydrochloric acid solution contains an oxidant; S4: adding part of the blank organic phase into a container, and then adding 20% ​​of the volume of the rare earth solution obtained in step S2, stirring for 30 minutes, separating the first aqueous phase, and the remainder is the first organic phase; S5: adding 10% of the mass of the terbium-dysprosium-holmium oxide particles dissolved in step S2 to the first aqueous phase obtained in step S4 to prepare a rare earth solution, adding the solution to the first organic phase, stirring for 60 minutes, separating the aqueous phase as the second aqueous phase, and the remainder as the second organic phase; S6: adding 10% of the mass of the terbium-dysprosium-holmium oxide particles dissolved in step S2 to the second aqueous phase obtained in step S5 to prepare a rare earth solution, adding part of the blank organic phase obtained in step S3, stirring for 60 minutes, separating the aqueous phase as the third aqueous phase, and the remaining as the third organic phase, wherein the amount of the blank organic phase added is the same as the amount of the blank organic phase added in step S4; S7 The second organic phase and the third organic phase were subjected to hydrochloric acid back extraction and EDTA titration to determine the load concentrations. The measured results were 0.185-0.200 mol / L and 0.160-0.185 mol / L, respectively, which were in line with expectations. The oxidant in the hydrochloric acid solution in step S3 is at least one of hydrogen peroxide and percarbonic acid amide; The rare earth solution in step S4, S5 or S6 is added by micron-level spraying followed by addition of the organic phase.

2. The process for extracting and separating rare earth terbium, dysprosium and holmium oxides according to claim 1, characterized in that: The concentration of hydrochloric acid in step S2 is 30-31%wt%.

3. The process for extracting and separating rare earth terbium, dysprosium and holmium oxides according to claim 1, characterized in that: The content of oxidant in the hydrochloric acid solution in step S3 is 2 wt %.

4. The process for extracting and separating rare earth terbium, dysprosium and holmium oxides according to claim 1, characterized in that: The content of terbium, dysprosium and holmium oxide in step S1 is greater than 99%.

5. The process for extracting and separating rare earth terbium, dysprosium and holmium oxides according to claim 1, characterized in that: The concentration of the hydrochloric acid solution in step S3 is 30-31 wt %.