Preparation method of electronic-grade dysprosium oxide with large specific surface area

Abstract

The invention relates to the technical field of electronic-grade dysprosium oxide, in particular to a preparation method of electronic-grade dysprosium oxide with fine granularity and large specific surface area. Comprising the four steps of Dy2 (C2O4) 3 preparation, firing, ball milling and performance testing. According to the prepared electronic-grade dysprosium oxide with the large specific surface area, the particle size of the dysprosium oxide powder is 0.5-2.5 microns, the specific surface area reaches 20-30m < 2 > / g, the ignition loss is less than 1%, and the application is wide.

Description

Technical Field

[0001] The invention relates to the technical field of electronic-grade dysprosium oxide, in particular to a method for preparing electronic-grade dysprosium oxide with a large specific surface area. Background Art

[0002] In recent years, the demand for rare earth downstream application market has increased rapidly, and the continuous adaptation to the customized demand of users for rare earth materials in high-end products has great significance for the development of my country's new materials field. At present, my country's rare earth oxides have more low- and medium-end products, fewer high-value-added material products, and lack of international market competitiveness. Most of my country's rare earth products are graded according to chemical composition and purity, and few can be graded according to physical properties and user requirements, such as electronic grade, ceramic grade, laser grade, etc., and specific surface area, valence state, particle size, etc., resulting in low pricing and inability to adapt to the downstream application market.

[0003] Large specific surface area electronic grade dysprosium oxide refers to dysprosium oxide (Dy2O3) material with extremely high specific surface area and purity that meets the application standards of the electronic industry. Due to its unique physical and chemical properties, this material has shown important application value in the fields of electronics, magnetism, optics and catalysis.

[0004] Usually has the following characteristics:

[0005] High specific surface area: A large specific surface area means that the unit mass of dysprosium oxide has a large surface area, which is conducive to enhancing the contact area between the material and the surrounding environment, improving the reaction activity, adsorption capacity and carrier transfer efficiency. In electronic devices, dysprosium oxide with a high specific surface area can improve the charge transfer path and enhance device performance.

[0006] Electronic grade purity: Electronic grade dysprosium oxide requires extremely low impurity content, usually reaching 99.99% or even 99.999% purity. High purity is essential for the stability and reliability of electronic devices, and can avoid problems such as reduced conductivity, increased resistance, and magnetic property degradation caused by impurities.

[0007] Nanostructure and micromorphology: Large specific surface area is usually associated with nanoscale particle size or special pore structure. Nano-dysprosium oxide has quantum size effect and surface effect, which can significantly change its magnetic, optical, electrical and other properties, and is suitable for the preparation of high-performance nano-composite materials and films.

[0008] Excellent magnetic properties: Dysprosium oxide, as a rare earth element, is known for its unique high magnetic moment and magnetic anisotropy. Electronic-grade dysprosium oxide with large specific surface area can still maintain good magnetic properties under high frequency and high temperature conditions, and is often used to prepare high-performance permanent magnetic materials, magnetic recording media, magnetic refrigeration materials, etc.

[0009] The preparation of electronic-grade dysprosium oxide with large specific surface area usually adopts advanced chemical synthesis technology, such as sol-gel method, microemulsion method, ultrasonic atomization spray pyrolysis method, etc., aiming to achieve nano-sizing, homogenization and optimization of pore structure of particles. The common characteristics of these methods include:

[0010] Refined raw material preparation: Select high-purity dysprosium sources (such as dysprosium metal, dysprosium salts) and perform strict pretreatment to ensure the purity of the raw materials.

[0011] Fine control of reaction conditions: By precisely regulating reaction temperature, pH, stirring speed, reaction time and other parameters, the production of dysprosium oxide particles with a high specific surface area is guided.

[0012] Post-processing optimization: The initially synthesized dysprosium oxide is subjected to post-processing such as grinding, grading, and pickling to further improve the purity, adjust the particle size distribution, and optimize the pore structure.

[0013] CN115159557B provides a method for preparing nano-dysprosium oxide, comprising: adding dysprosium rare earth liquid, ammonia solution and ammonium sulfate solution to a reaction vessel filled with bottom water at the same time to carry out precipitation reaction; after the precipitation reaction is completed, filtering, washing, vacuum drying and calcining the precipitation reaction product to obtain nano-dysprosium oxide powder. Ammonium sulfate is added during the preparation of nano-dysprosium oxide precipitation, and rare earth hydroxide and rare earth sulfate complex salt are mutually converted during the precipitation process. The final precursor can be maintained at a certain nanometer size even after filtering and washing, solving the problem of rare earth hydroxide not settling and filtering and washing through. However, the specific surface area is small. Summary of the invention

[0014] In view of the shortcomings of the prior art, the present invention provides a method for preparing electronic-grade dysprosium oxide with a large specific surface area. The preparation process is simple and the prepared product has excellent performance. The preparation method comprises four steps: preparation of Dy2(C2O4)3, calcination, ball milling, and performance testing. The specific preparation method is as follows:

[0015] Preparation of S1 Dy2(C2O4)3:

[0016] S11: In a reaction vessel, prepare a 0.4-0.5 mol / L DyCl3 solution;

[0017] S12 prepares a 10 wt % oxalic acid aqueous solution for standby use;

[0018] S13 prepares polyacrylamide solution for standby use;

[0019] S14: adding the oxalic acid aqueous solution in step S12 to the reaction container in step S11, and at the same time adding the polyacrylamide solution prepared in step S13 to the reaction container in step S11, precipitating and crystallizing, aging for 1 to 3 hours after crystallization is completed, and releasing the mother liquid water; by adding the polyacrylamide solution during the crystallization process, the viscosity and tension of the solution can be adjusted, and it is easier to generate flocculent, fluffy, and large specific surface area solids;

[0020] S15 Add pure water to the reaction container, wash several times until the pH is ≥ 6 and the conductivity is < 20 μS / cm, and filter;

[0021] S16: adding the solid filtered in step S15 to the polyacrylamide solution prepared in step S13, stirring evenly to obtain a mixed solution;

[0022] S2 Burn:

[0023] S21 spray-drying the mixed solution obtained in step S16; by spray drying, the mixed solution is instantly evaporated and burned to generate ultrafine powder with a high specific surface area, and at the same time, part of the undecomposed polyacrylamide can further generate gas during the calcination process, which is conducive to the production of powder with a large specific surface area;

[0024] S22: placing the Dy2(C2O4)3 solid obtained by spray drying in step S21 into a crucible, heating it in a muffle furnace, introducing air, adjusting the temperature to 550°C and calcining it for 1 hour, then raising the temperature to 650°C and calcining it for 1 hour, and then rapidly cooling it to room temperature; by calcining with staged temperature control, the prepared powder particles can be made more uniform;

[0025] S3 ball mill:

[0026] The Dy2O3 obtained in step S22 is added to pure water to prepare a slurry with a solid content of 8%, and then placed in a ball mill for wet ball milling. Ultrasonic dispersion is then used to further disperse the slurry, and the sample is sent for testing after the water is dried. The large particles are broken into smaller particles by ultrasonic waves to prevent agglomeration and improve the dispersion degree and specific surface area of ​​the powder. The particle size distribution is controlled by the wet grinding process to achieve an ideal specific surface area.

[0027] S4 performance test:

[0028] The particle size, ignition loss and specific surface area of ​​Dy2O3 were measured, and the values ​​were D50 = 0.5-2.5 μm; ignition loss was 0.93-0.97%; specific surface area = 20-30 m 2 / g.

[0029] Furthermore, the concentration of the polyacrylamide solution prepared in step S13 is 0.005 wt %.

[0030] Furthermore, in step S14, the volume of the oxalic acid aqueous solution added is 20 to 50 times the volume of the polyacrylamide solution added, and the ratio of the volume of the oxalic acid aqueous solution added to the volume of the polyacrylamide solution added is strictly controlled to control the solution viscosity and the dispersibility of the crystalline solid within a preferred range.

[0031] Furthermore, the mass of the solid after the suction filtration in step S16 is 50% of the mass of the added polyacrylamide solution.

[0032] Furthermore, the spray drying temperature in step S21 is 300-350°C.

[0033] Furthermore, the rapid cooling time in step S22 is 0.2 to 0.5 hours. Rapid cooling is used to generate micro cracks inside the particles or transform them into a finer powder structure, thereby increasing the surface area.

[0034] Furthermore, the rapid cooling method in step S22 is to use a low-temperature inert gas to cool the calcined dysprosium oxide. The inert gas is nitrogen or argon. The gas molecules can quickly penetrate into the powder, causing the powder to crack and quickly cool down to obtain a powder with a smaller particle size.

[0035] Furthermore, the ultrasonic frequency in step S3 is 10 to 20 kHz.

[0036] The electronic grade dysprosium oxide with large specific surface area prepared by the present invention has a specific surface area of ​​20 to 30 m 2 / g, ignition reduction less than 1%, widely used. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] A method for preparing electronic-grade dysprosium oxide with a large specific surface area includes four steps: preparation of Dy2(C2O4)3, calcination, ball milling, and performance testing. The specific preparation method is as follows:

[0040] Preparation of S1 Dy2(C2O4)3:

[0041] S11 In a reaction vessel, prepare 1 L of 0.4 mol / L DyCl3 solution;

[0042] S12 prepares a 10 wt % oxalic acid aqueous solution for standby use;

[0043] S13 prepares a 0.005 wt % polyacrylamide solution for standby use;

[0044] S14: adding the oxalic acid aqueous solution in step S12 to the reaction container of step S11, and at the same time adding the polyacrylamide solution prepared in step S13 to the reaction container of step S11, precipitating crystals, the amount of oxalic acid added is 1.05 times its theoretical amount, and the added volume of the oxalic acid aqueous solution is 30 times the added volume of the polyacrylamide solution, and the crystallization is completed, aging for 1 to 3 hours, and releasing the mother liquor water;

[0045] S15 Add pure water to the reaction container, wash several times until the pH is ≥ 6 and the conductivity is < 20 μS / cm, and filter;

[0046] S16: adding the solid filtered in step S15 to the polyacrylamide solution prepared in step S13, stirring evenly to obtain a mixed solution, wherein the mass of the solid filtered is 50% of the mass of the added polyacrylamide solution;

[0047] S2 Burn:

[0048] S21 spray-drying the mixed solution obtained in step S16 at a spray drying temperature of 300-350° C.;

[0049] S22: the Dy2(C2O4)3 solid obtained by spray drying in step S21 is placed in a crucible, heated in a muffle furnace, air is introduced, the temperature is adjusted to 550°C and calcined for 1 hour, then the temperature is raised to 650°C, calcined for 1 hour, and then rapidly cooled to room temperature, the rapid cooling time is 0.3h;

[0050] S3 ball mill:

[0051] The Dy2O3 obtained in step S22 is added to pure water to prepare a slurry with a solid content of 8%, and then placed in a ball mill for wet ball milling, and then further dispersed by ultrasonic wave, and the sample is sent for testing after the water is dried, and the ultrasonic frequency is 15kHz;

[0052] S4 performance test:

[0053] The particle size, ignition loss and specific surface area of ​​Dy2O3 were measured, and the values ​​were D50 = 1.0 μm; ignition loss = 0.95%; specific surface area = 26.8 m 2 / g.

[0054] Example 2

[0055] A method for preparing electronic-grade dysprosium oxide with a large specific surface area includes four steps: preparation of Dy2(C2O4)3, calcination, ball milling, and performance testing. The specific preparation method is as follows:

[0056] Preparation of S1 Dy2(C2O4)3:

[0057] S11 In a reaction vessel, prepare 1 L of 0.5 mol / L DyCl3 solution;

[0058] S12 prepares a 10 wt % oxalic acid aqueous solution for standby use;

[0059] S13 prepares a 0.005 wt % polyacrylamide solution for standby use;

[0060] S14: adding the oxalic acid aqueous solution in step S12 to the reaction container of step S11, and at the same time adding the polyacrylamide solution prepared in step S13 to the reaction container of step S11, precipitating crystals, the amount of oxalic acid added is 1.05 times its theoretical amount, and the volume of the oxalic acid aqueous solution added is 40 times the volume of the polyacrylamide solution added, and the crystallization is completed, aging for 1 to 3 hours, and releasing the mother liquor water;

[0061] S15 Add pure water to the reaction container, wash several times until the pH is ≥ 6 and the conductivity is < 20 μS / cm, and filter;

[0062] S16: adding the solid filtered in step S15 to the polyacrylamide solution prepared in step S13, stirring evenly to obtain a mixed solution, wherein the mass of the solid filtered is 50% of the mass of the added polyacrylamide solution;

[0063] S2 Burn:

[0064] S21 spray-drying the mixed solution obtained in step S16 at a spray drying temperature of 300-350° C.;

[0065] S22: placing the Dy2(C2O4)3 solid obtained by spray drying in step S21 into a crucible, heating it in a muffle furnace, introducing air, adjusting the temperature to 550°C and calcining it for 1 hour, then raising the temperature to 650°C and calcining it for 1 hour, and then rapidly cooling it to room temperature, the rapid cooling time is 0.2h, and the rapid cooling method is to use a low-temperature inert gas to cool the calcined dysprosium oxide, the inert gas is low-temperature nitrogen, and the nitrogen temperature is 1-5°C;

[0066] S3 ball mill:

[0067] The Dy2O3 obtained in step S22 is added to pure water to prepare a slurry with a solid content of 8%, and then placed in a ball mill for wet ball milling, and then further dispersed by ultrasound, and the sample is sent for testing after the water is dried, and the ultrasonic frequency is 20kHz;

[0068] S4 performance test:

[0069] The particle size, ignition loss and specific surface area of ​​Dy2O3 were measured, and the values ​​were D50 = 0.6 μm; ignition loss = 0.93%; specific surface area = 29.2 m 2 / g.

[0070] Example 3

[0071] A method for preparing electronic-grade dysprosium oxide with a large specific surface area includes four steps: preparation of Dy2(C2O4)3, calcination, ball milling, and performance testing. The specific preparation method is as follows:

[0072] Preparation of S1 Dy2(C2O4)3:

[0073] S11 In a reaction vessel, prepare 1 L of 0.5 mol / L DyCl3 solution;

[0074] S12 prepares a 10 wt % oxalic acid aqueous solution for standby use;

[0075] S13 prepares a 0.005 wt % polyacrylamide solution for standby use;

[0076] S14: adding the oxalic acid aqueous solution in step S12 to the reaction container of step S11, and at the same time adding the polyacrylamide solution prepared in step S13 to the reaction container of step S11, precipitating crystals, the amount of oxalic acid added is 1.05 times its theoretical amount, and the added volume of the oxalic acid aqueous solution is 50 times the added volume of the polyacrylamide solution, and after the crystallization is completed, aging for 1 to 3 hours, and releasing the mother liquor water;

[0077] S15 Add pure water to the reaction container, wash several times until the pH is ≥ 6 and the conductivity is < 20 μS / cm, and filter;

[0078] S16: adding the solid filtered in step S15 to the polyacrylamide solution prepared in step S13, stirring evenly to obtain a mixed solution, wherein the mass of the solid filtered is 50% of the mass of the added polyacrylamide solution;

[0079] S2 Burn:

[0080] S21 spray-drying the mixed solution obtained in step S16 at a spray drying temperature of 300-350° C.;

[0081] S22: placing the Dy2(C2O4)3 solid obtained by spray drying in step S21 into a crucible, heating it in a muffle furnace, introducing air, adjusting the temperature to 550°C and calcining it for 1 hour, then raising the temperature to 650°C and calcining it for 1 hour, and then rapidly cooling it to room temperature, the rapid cooling time is 0.3h, and the rapid cooling method is to use a low-temperature inert gas to cool the calcined dysprosium oxide, the inert gas is low-temperature argon, and the argon temperature is 1-5°C;

[0082] S3 ball mill:

[0083] The Dy2O3 obtained in step S22 is added to pure water to prepare a slurry with a solid content of 8%, and then placed in a ball mill for wet ball milling, and then further dispersed by ultrasound, and the sample is sent for testing after the water is dried, and the ultrasonic frequency is 20kHz;

[0084] S4 performance test:

[0085] The particle size, ignition loss and specific surface area of ​​Dy2O3 were measured, and the values ​​were D50 = 0.8 μm; ignition loss = 0.95%; specific surface area = 27.4 m 2 / g.

[0086] Comparative Example 1

[0087] In step S14 of Example 2, only the oxalic acid aqueous solution is added without the polyacrylamide solution. The rest is the same as Example 2 and will not be described again.

[0088] Comparative Example 2

[0089] The spray drying in step S21 of Example 2 is changed to ordinary evaporation drying, and the rest is the same as Example 2 and will not be described in detail.

[0090] Comparative Example 3

[0091] The ultrasonic further dispersion step in step S3 of Example 1 is removed, and the rest is the same as Example 1 and will not be described in detail.

[0092] Comparative Example 4

[0093] The rapid cooling in step S22 of Example 1 is changed to natural cooling, and the rest is the same as Example 1 and will not be described in detail.

[0094] The electronic grade dysprosium oxide prepared in the examples of the present invention and the comparative examples was subjected to performance tests, and the results are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] It can be seen from the data in the above table that the test data of Examples 1 to 3 are all good, and the specific surface area of ​​the dysprosium oxide powder is 20 to 30 m 2 / g, and the reduction on ignition is less than 1%. The data of comparative examples 1 to 4 show that the addition of polyacrylamide solution, rapid cooling, ultrasonic further dispersion, and spray drying can all improve the performance of the prepared dysprosium oxide, and their comprehensive application and synergistic effect can improve the performance more significantly.

Claims

1. A method for preparing electronic grade dysprosium oxide with large specific surface area, characterized in that: It includes four steps: preparation of Dy2(C2O4)3, calcination, ball milling, and performance testing. The specific preparation method is as follows: Preparation of S1 Dy2(C2O4)3: S11: In a reaction vessel, prepare a 0.4-0.5 mol / L DyCl3 solution; S12 prepares a 10 wt % oxalic acid aqueous solution for standby use; S13 prepares polyacrylamide solution for standby use; S14: adding the oxalic acid aqueous solution in step S12 to the reaction container in step S11, and at the same time adding the polyacrylamide solution prepared in step S13 to the reaction container in step S11, precipitating crystals, aging for 1 to 3 hours after crystallization is completed, and releasing the mother liquor water; S15 Add pure water to the reaction container, wash several times until the pH is ≥ 6 and the conductivity is < 20 μS / cm, and filter; S16: adding the solid filtered in step S15 to the polyacrylamide solution prepared in step S13, stirring evenly to obtain a mixed solution; S2 Burn: S21 spray-drying the mixed solution obtained in step S16; S22: placing the Dy2(C2O4)3 solid obtained by spray drying in step S21 into a crucible, heating it in a muffle furnace, introducing air, adjusting the temperature to 550°C and calcining it for 1 hour, then raising the temperature to 650°C and calcining it for 1 hour, and then rapidly cooling it to room temperature; S3 ball mill: The Dy2O3 obtained in step S22 is added to pure water to prepare a slurry with a solid content of 8%, and then placed in a ball mill for wet ball milling, and then further dispersed by ultrasonic wave, and the water is dried and then sent for sample testing; S4 performance test: The particle size, ignition loss and specific surface area of ​​Dy2O3 were measured, and the values ​​were D50 = 0.5-2.5 μm; ignition loss was 0.93-0.97%; specific surface area = 20-30 m 2 / g.

2. The method for preparing electronic grade dysprosium oxide according to claim 1, characterized in that: The concentration of the polyacrylamide solution prepared in step S13 is 0.005 wt %.

3. The method for preparing electronic grade dysprosium oxide according to claim 1, characterized in that: In step S14, the volume of the oxalic acid aqueous solution added is 20 to 50 times the volume of the polyacrylamide solution added.

4. The method for preparing electronic grade dysprosium oxide according to claim 1, characterized in that: The mass of the solid after the suction filtration in step S16 is 50% of the mass of the added polyacrylamide solution.

5. The method for preparing electronic grade dysprosium oxide according to claim 1, characterized in that: The spray drying temperature in step S21 is 300-350°C.

6. The method for preparing electronic grade dysprosium oxide according to claim 1, characterized in that: The rapid cooling time in step S22 is 0.2 to 0.5 h.

7. The method for preparing electronic grade dysprosium oxide according to claim 6, characterized in that: The rapid cooling method in step S22 is to use a low-temperature inert gas to cool the calcined dysprosium oxide, and the inert gas is nitrogen or argon.

8. The method for preparing electronic grade dysprosium oxide according to claim 1, characterized in that: The ultrasonic frequency in step S3 is 10-20 kHz.

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