Device and method for preparing NANO rare earth oxide by means of cooperation of ultrasonic waves and microwaves

Abstract

The present invention relates to the technical field of rare earth, and in particular to a device and method for preparing a nano rare earth oxide by means of cooperation of ultrasonic waves and microwaves. By using the device, a nano rare earth oxide is prepared by means of processes such as stirring, reacting, filtering, washing, drying, and burning. The "internal heating" of microwaves and "cavitation" of ultrasonic waves can effectively accelerate the reaction, shorten the reaction time, and speed up the reaction rate, so as to obtain nanomaterials with no agglomeration and uniform particle size; the heat effect of the ultrasonic waves provides enough energy for ions waiting for nucleation in a solution, so as to promote formation of crystal nucleuses; and the chemical effect of ultrasonic waves can effectively promote primary nucleation and secondary nucleation of crystals, and provides energy for ions which cannot be nucleated. Stirring is implemented by means of the "cavitation" and mechanical effect of ultrasonic waves, and the strength of stirring is far higher than that of common mechanical stirring, effectively hindering grain growth, and thus obtaining superfine powder having a small particle size, good dispersity and complete crystallization.

Description

Device and method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves Technical Field

[0001] The present invention relates to the field of rare earths, and in particular to a device and method for preparing nano rare earth oxides by collaborative use of ultrasound and microwaves. Background Art

[0002] Rare earth elements (REEs) are a collective term for 17 elements, including the 15 lanthanide elements and scandium (Sc) and yttrium (Y) from Group III. With the continuous advancement of science and technology, the application of rare earth elements has rapidly expanded and broadened. Today, rare earth elements are not only present in all aspects of national economy and people's livelihoods, but have also become irreplaceable key core materials in aviation, aerospace, and military fields. The constant flow of vehicles, the streaking speed of high-speed trains, the glittering pearls and gemstones, the vibrant colors of film and television, and countless other scenes are all closely related to rare earth elements. Rare earth materials are also key supporting materials for 10 key development areas outlined in my country's 2030 National Vision Development Plan: high-end CNC machine tools and robots, aerospace equipment, marine engineering equipment and high-tech ships, power equipment, agricultural machinery and equipment, biopharmaceuticals and high-performance medical devices, advanced rail transit equipment, energy-saving and new energy vehicles, electronics and information technology, and national defense and military industries. However, rare earth elements are a precious, non-renewable natural resource and are recognized globally as a critical mineral resource. According to 2021 statistics from the United States Geological Survey (USGS), the world's total rare earth resource reserves (hereinafter referred to as REO) are 120 million tons, of which my country holds 44 million tons, accounting for approximately 37%. To date, of the more than 250 rare earth minerals discovered in nature, only about 10 can be used for industrial rare earth production.

[0003] Rare earth oxides are insoluble in water and alkali, but readily soluble in acids (except concentrated H₂SO₄). Nanosized rare earth oxides exhibit excellent corrosion resistance, heat resistance, magnetism, strength, and dielectric constant, making them widely used in a wide range of fields, including catalysts, fluorescence, dielectric insulated field luminescence, waveguides, magnetism, coatings, superconducting materials, and fuel cells. When nanosized rare earth oxides are sphericalized, they possess superior specific surface area, surface atomic number, surface energy, fluidity, and dispersibility, resulting in superior optical, electrical, magnetic, mechanical, and chemical properties. This opens up a wider range of applications for nanosized spherical rare earth oxides.

[0004] Currently, there are relatively many methods for preparing nanoscale rare earth oxides. However, nanomaterials are prone to structural defects and agglomeration if improperly stored or prepared, resulting in poor quality powders. This, in turn, limits the application of rare earth oxides. Therefore, in-depth research on rare earth oxide preparation technologies has important academic value and is crucial for expanding the functions and applications of nano-rare earth oxides.

[0005] The present invention is proposed in view of the deficiencies in the prior art. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a method and device for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves.

[0007] The present invention can be achieved through the following technical solutions:

[0008] The present invention discloses a device for preparing nano rare earth oxides by synergistically using ultrasound and microwaves. The device comprises a storage tank, wherein a stirring device is provided on the storage tank, a feeding port is further provided on the upper end of the storage tank, a discharging port is further fixed to the bottom of the storage tank, a circulation pipeline is fixed to the discharging port, a plurality of reaction devices are further provided on one side of the storage tank, the reaction device comprises a reaction tank, a feeding pipe is fixed to the bottom of the reaction tank, a solenoid valve is provided on the feeding pipe, the feeding pipe is evenly connected to a circulation pipeline, a circulation pump is further provided on the circulation pipeline, an exhaust port is provided on the top of each reaction tank, the exhaust port is evenly connected to the exhaust pipe on the storage tank, a plurality of microwave generators are further provided on both sides of the reaction tank, and an ultrasonic vibration rod is further fixed in the reaction tank.

[0009] Preferably, the stirring device includes a stirring motor fixed to the top of the storage tank, the output end of the stirring motor is fixed to the stirring shaft in the storage tank, and a stirring blade is also fixed on the stirring shaft.

[0010] Preferably, a temperature sensor is also fixed on the storage tank.

[0011] Preferably, a discharge pipe with a solenoid valve is also fixed to the bottom of the storage tank.

[0012] The present invention also discloses a method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves, comprising the following steps:

[0013] Step 1. Stirring: Discharge a certain concentration of rare earth raw material solution and precipitant solution into a storage tank, and stir the storage tank through a stirring mechanism to fully mix the two;

[0014] Step 2. Reaction: The mixed solution is discharged into a reaction tank, microwaves are emitted into the reaction tank by a microwave generator, and ultrasonic generator drives an ultrasonic vibrating rod to generate ultrasonic waves to fully react the solution;

[0015] Step 3. Filtration: Filter the solution after the reaction in step 2 to obtain a precipitate;

[0016] Step 4. Washing: Wash the precipitate obtained in step 3 multiple times with a detergent;

[0017] Step 5. Drying: Place the washed precipitate in a drying oven to dry;

[0018] Step 6. Calcination: The dried product is placed in a high-temperature furnace for calcination to obtain rare earth oxides.

[0019] Preferably, the precipitant is a mixture of one or more of ammonium bicarbonate, ammonium citrate and urea.

[0020] Preferably, the detergent in step 4 is a mixture of one or more of water or anhydrous ethanol.

[0021] Preferably, the concentration of the rare earth element in the rare earth solution is 0.05-0.5 mol / L, and the concentration of the precipitant solution is 0.5-5 mol / L.

[0022] Preferably, in step 2, the ultrasonic power is 200-20000W, and the microwave power is 200-1000W.

[0023] Preferably, the calcination temperature in step 6 is 700-1100°C.

[0024] Compared with the existing technology, the present invention has the following advantages:

[0025] 1. The "internal heating" of microwaves and the "cavitation effect" of ultrasound can effectively accelerate the reaction, shorten the reaction time, speed up the reaction rate, and obtain nanomaterials with no agglomeration and uniform particle size.

[0026] 2. Make full use of the "cavitation effect", thermal effect and mechanical effect of ultrasound, and coordinate them with the selective heating and "internal heating" of microwaves to achieve the effect of 1+1 greater than 2. Utilize the high temperature, high pressure and high energy generated in this mode to enable the ions in the solution to quickly generate a large number of crystal nuclei in a relatively short period of time. Combined with the strong shock waves and microjets of ultrasound, the further growth of the crystal nuclei is hindered, and the already agglomerated particles are broken for secondary crystallization, thereby obtaining nanopowders with uniform particle size distribution and no agglomeration.

[0027] 3. Ultrasonic waves are both waves and energy. During the transmission process, they easily interact with the medium, generating a series of special effects and functions, such as cavitation, thermal effect, mechanical effect and chemical effect. Ultrasonic waves are introduced into the liquid phase precipitation method, and the unique effect is used to prepare nano-powder materials. The principle of its implementation is that at the moment of ultrasonic emission, a large number of tiny bubbles are generated due to "cavitation". The bubbles burst in an instant, generating a high temperature of 7000 to 19000K and a high pressure of more than 500 atm, which provide energy for the formation of crystal nuclei, thereby promoting the crystallization and growth of the crystal nuclei. At the same time, the mechanical stirring effect generated by the ultrasonic wave during the reaction process hinders the growth and agglomeration of the crystal nuclei. Under the interaction of multiple effects, the purpose of fast reaction speed and promoting solution dispersion is achieved.

[0028] 4. The thermal effect of ultrasound provides sufficient energy to the ions in the solution to be nucleated, promoting the formation of crystal nuclei. The chemical effect of ultrasound can effectively promote primary and secondary nucleation of crystals, providing energy for ions that cannot nucleate. The "cavitation effect" and mechanical action of ultrasound can act as a stirring agent, with an intensity far greater than that of ordinary mechanical stirring, effectively hindering grain growth, thereby obtaining ultrafine powders with small particle size, good dispersion, and complete crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0030] FIG1 is a schematic diagram of the structure of the device used in the present invention;

[0031] FIG2 is a process flow chart of the present invention;

[0032] FIG3 is a scanning electron microscope (SEM) image of yttrium oxide in Example 1;

[0033] FIG4 is a scanning electron microscope (SEM) image of lanthanum oxide of Example 2;

[0034] FIG5 is a transmission electron microscope (TEM) image of dysprosium oxide in Example 3;

[0035] In Figure 1: 1. Storage tank; 2. Stirring motor; 3. Stirring shaft; 4. Stirring blade; 5. Inlet; 6. Outlet; 7. Reactor; 8. Reactor; 9. Ultrasonic vibrator; 10. Microwave generator; 11. Exhaust pipe; 12. Solenoid valve; 13. Feed pipe; 14. Circulation pipe; 15. Discharge pipe; 16. Circulation pump; 17. Temperature sensor.

[0036] DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings: Example

[0038] Yttrium chloride is used as raw material and urea is used as precipitant, and is discharged into the storage tank 1 through the feed port 5. 3+ The concentration is 0.05 mol / L, the concentration of urea is 0.5 mol / L, the stirring shaft 3 is driven to rotate by the stirring motor 2, and the stirring blade 4 rotates with the stirring shaft 3. After the yttrium chloride and urea are fully mixed, the solenoid valve 12 on the discharge pipe 13 is opened, and the circulation pump 16 is turned on. The circulation pump 16 extracts the solution in the storage tank 1 and discharges it into each reaction tank 8 through the circulation pipe 14. The microwave generator emits microwaves to the reaction tank 8, and ultrasonic waves are generated by the ultrasonic vibration rod 9, wherein the ultrasonic power is: 1800 W, the microwave power is 1000 W, and the ultrasonic mode is 2:1; the reaction of the raw materials is accelerated by the synergistic effect of ultrasonic waves and microwaves, and the gas generated by the reaction is discharged into the storage tank 1 through the exhaust pipe 11 and discharged and collected through the feed port 5.

[0039] After the reaction is completed, the solution in the reaction tank 8 is extracted by the circulation pump 16 and discharged through the discharge pipe 15 for collection.

[0040] The reaction solution was centrifuged and filtered to obtain a precipitate, which was then washed three times with deionized water and three times with anhydrous ethanol and then centrifuged;

[0041] After centrifugation, the precipitate was dried in a drying oven for 4 hours;

[0042] The completely dried yttrium oxide precursor is placed in a high-temperature furnace at 700°C and burned for 5 hours to obtain spherical yttrium oxide of about 50 nanometers. Example

[0043] Lanthanum chloride is used as raw material and ammonium bicarbonate is used as precipitant. The solution is discharged into the storage tank 1 through the feed port 5. 3+ The concentration is 0.2 mol / L, and the concentration of ammonium bicarbonate is 3.0 mol / L. The stirring shaft 3 is driven to rotate by the stirring motor 2, and the stirring blade 4 rotates with the stirring shaft 3. After the lanthanum chloride and ammonium bicarbonate are fully mixed, the solenoid valve 12 on the discharge pipe 13 is opened, and the circulation pump 16 is turned on. The circulation pump 16 extracts the solution in the storage tank 1 and discharges it into each reaction tank 8 through the circulation pipe 14. The microwave generator emits microwaves to the reaction tank 8, and ultrasonic waves are generated by the ultrasonic vibration rod 9, wherein the ultrasonic power is: 1000 W, the microwave power is 600 W, and the ultrasonic mode is 2:1; the reaction of the raw materials is accelerated by the synergistic effect of ultrasonic waves and microwaves, and the gas generated by the reaction is discharged into the storage tank 1 through the exhaust pipe 11 and discharged and collected through the feed port 5.

[0044] After the reaction is completed, the solution in the reaction tank 8 is extracted by the circulation pump 16 and discharged through the discharge pipe 15 for collection.

[0045] The reaction solution was centrifuged and filtered to obtain a precipitate, which was washed three times with deionized water and centrifuged;

[0046] After centrifugation, the precipitate was placed in a drying oven to dry for 5 hours;

[0047] The completely dried lanthanum oxide precursor was placed in a high-temperature furnace at 900°C and burned for 4 hours to obtain needle-shaped nano-lanthanum oxide of about 50 nm. Example

[0048] Dysprosium chloride is used as raw material, ammonium citrate and urea are used as precipitants, and discharged into the storage tank 1 through the feed port 5. 3+ The concentration is 0.5 mol / L, ammonium citrate and urea are prepared into a mixed solution at a concentration ratio of 2:1, and the total concentration is 5.0 mol / L. The stirring shaft 3 is driven to rotate by the stirring motor 2, and the stirring blade 4 rotates with the stirring shaft 3. After the dysprosium chloride is fully mixed with urea and ammonium citrate, the solenoid valve 12 on the discharge pipe 13 is opened, and the circulation pump 16 is turned on. The circulation pump 16 extracts the solution in the storage tank 1 and discharges it into each reaction tank 8 through the circulation pipe 14. The microwave generator emits microwaves to the reaction tank 8, and ultrasonic waves are generated by the ultrasonic vibration rod 9, wherein the ultrasonic power is: 200 W, the microwave power is 300 W, and the ultrasonic mode is 1:1; the reaction of the raw materials is accelerated by the synergistic effect of ultrasonic waves and microwaves, and the gas generated by the reaction is discharged into the storage tank 1 through the exhaust pipe 11 and discharged and collected through the feed port 5.

[0049] After the reaction is completed, the solution in the reaction tank 8 is extracted by the circulation pump 16 and discharged through the discharge pipe 15 for collection.

[0050] The reaction solution was centrifuged and filtered to obtain a precipitate, which was washed three times with anhydrous ethanol and centrifuged;

[0051] After centrifugation, the precipitate was placed in a drying oven to dry for 5 hours;

[0052] The completely dried dysprosium oxide precursor is placed in a high-temperature furnace at 1100° C. and calcined for 2 hours to obtain spherical nano-dysprosium oxide of about 80 nm.

[0053] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the technical principles of the present invention. These changes, modifications, substitutions and variations should also be regarded as the scope of protection of the present invention.

Claims

1. A device for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves, characterized in that: It comprises a storage tank, on which a stirring device is provided, a feeding port is also provided at the upper end of the storage tank, a discharging port is also fixed at the bottom of the storage tank, a circulating pipe is fixed on the discharging port, a plurality of reaction devices are also provided on one side of the storage tank, the reaction device comprises a reaction tank, a feeding pipe is fixed at the bottom of the reaction tank, a solenoid valve is provided on the feeding pipe, the feeding pipe is connected with a uniform circulating pipe, a circulating pump is also provided on the circulating pipe, an exhaust port is provided at the top of the reaction tank, the exhaust port is connected with the exhaust pipe on the storage tank, a plurality of microwave generators are also provided on both sides of the reaction tank, and an ultrasonic vibration rod is also fixed in the reaction tank.

2. The device for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 1, characterized in that: The stirring device comprises a stirring motor fixed on the top of the storage tank, the output end of the stirring motor is fixed to the stirring shaft in the storage tank, and a stirring blade is also fixed on the stirring shaft.

3. The device for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 1, characterized in that: A temperature sensor is also fixed on the storage tank.

4. The device for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 1, characterized in that: A discharge pipe with a solenoid valve is also fixed at the bottom of the storage tank.

5. A method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves, characterized in that: The following steps are involved: Step 1. Stirring: Discharge a rare earth chloride raw material solution and a precipitant solution of a certain concentration into a storage tank, and stir the storage tank through a stirring mechanism to fully mix the two; Step 2. Reaction: the mixed solution is discharged into a reaction tank, microwaves are emitted into the reaction tank by a microwave generator, and ultrasonic generator drives an ultrasonic vibrating rod to generate ultrasonic waves to make the solution fully react; Step 3. Filtration: Filter the solution after the reaction in step 2 to obtain a precipitate; Step 4. Washing: Wash the precipitate obtained in step 3 multiple times with a detergent; Step 5. Drying: Place the washed precipitate in a drying oven to dry; Step 6. Calcination: The dried product is placed in a high-temperature furnace for calcination to obtain rare earth oxides.

6. The method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 5, characterized in that: The precipitant is a mixture of one or more of ammonium bicarbonate, ammonium citrate and urea.

7. The method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 5, characterized in that: The detergent in step 4 is one or more mixtures of water or anhydrous ethanol.

8. The method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 5, characterized in that: The concentration of the rare earth element in the rare earth solution is 0.05-0.5 mol / L, and the concentration of the precipitant solution is 0.5-5 mol / L.

9. The method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 5, characterized in that: In step 2, the ultrasonic power is 200-20000W, and the microwave power is 200-1000W.

10. The method for preparing nano rare earth oxides by synergistic use of ultrasound and microwaves according to claim 5, characterized in that: The burning temperature in step 6 is: 700-1100°C.

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