Ultrafine high-purity rhenium powder and one-step reduction preparation method thereof

Abstract

This invention discloses an ultrafine graded high-purity rhenium powder and its one-step reduction preparation method, belonging to the technical field of rhenium powder preparation methods. The method includes: feeding high-purity ammonium perlite coarse particles into a closed fluidized bed mill protected by high-purity hydrogen gas; reducing the high-purity ammonium perlite coarse particles in a high-purity hydrogen pulsed gas flow at a pressure of 1.5-3 MPa and a pulse frequency of 5-20 Hz, the reduction treatment including: holding at 200-300℃ for 0.5-1.5 h, followed by holding at 350-450℃ for 1-3 h. This invention utilizes the synergistic effect of the kinetic and thermal energy of the high-pressure hydrogen gas flow to achieve simultaneous control of the physical crushing, chemical reduction, and crystal growth of ammonium perlite coarse particles, significantly shortening the production cycle and energy consumption, and obtaining high-purity ultrafine rhenium powder with a narrow particle size distribution and no agglomeration.

Description

Technical Field

[0001] This invention relates to the technical field of rhenium powder preparation methods, and particularly to an ultrafine graded rhenium powder and its one-step reduction preparation method. Background Technology

[0002] Impurity elements (especially C, O, N, and heavy metals such as Fe, Cr, and Ni) significantly reduce the ductility and high-temperature mechanical properties of rhenium metal. Simultaneously, particle size significantly affects the sintering activity and density of rhenium powder. Therefore, with increasing demands in application fields, the requirements for the purity and particle size of rhenium powder are constantly rising, with ultrafine (D...) being particularly important. 50 The demand for micro / nano-sized rhenium powder (< 10μm) and high purity (4N~5N grade) is becoming increasingly prominent.

[0003] Currently, the mainstream industrial method for preparing high-purity rhenium powder is the hydrogen reduction method. Its basic principle is to use hydrogen as a reducing agent to reduce rhenium oxides or ammonium salts to elemental rhenium at high temperatures. A typical process usually includes a pretreatment stage of mechanically crushing, grinding, and sieving industrial-grade ammonium perrylate, followed by a reduction stage where the sieved ammonium perrylate is reduced in a hydrogen atmosphere to obtain metallic rhenium powder. This type of method typically has low production efficiency and poor product dispersibility.

[0004] To address these issues, existing technologies employ two improvement methods: reduction process control and physical field assistance. For example, CN119407185A discloses a method for preparing high-purity rhenium powder, which uses a gradient high-temperature reduction strategy (low-temperature dehydration → medium-temperature reduction → high-temperature deep reduction), improving reduction efficiency to some extent. However, this method still uses mechanical crushing and ball milling (usually in air) in the pretreatment stage, easily introducing impurities such as Al, Si, Fe, and Cr. Furthermore, the crushed particles easily adsorb oxygen and moisture to form a passivation film, resulting in high temperatures (>900℃) and long reduction times required, leading to grain growth and difficulty in obtaining micro / nano-scale powders. As another example, CN119794323A discloses a method and apparatus for directly preparing high-purity rhenium powder from high-purity ammonium perrhenate, which introduces microwave heating and ultrasonic dispersion in the reduction furnace to improve material drying and prevent agglomeration during reduction. However, the ultrasonic waves in this technology mainly act on the macroscopic material layer, with limited dispersion effect on micro / nano particles. Moreover, this method does not solve the problems of raw material agglomeration and impurity introduction in the pretreatment stage.

[0005] Therefore, existing technologies for preparing micro / nano-scale high-purity rhenium powder still suffer from drawbacks such as high risk of impurity introduction, long process flow, and difficulty in particle size control. Furthermore, existing technologies often use ammonium perlite fine powder as raw material, preparing ultrapure rhenium powder through crushing, transporting, and reduction, which carries safety risks related to dust exposure, contaminant introduction, and hydrogen mixing with air. Therefore, there is an urgent need in this field for a method to prepare micro / nano-scale high-purity rhenium powder that can avoid impurity contamination, shorten the preparation process, precisely control product particle size, and is both safe and environmentally friendly. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a novel ultrafine-graded high-purity rhenium powder and its one-step reduction preparation method. This preparation method utilizes the characteristics of ammonium perrylate's crystal structure instability and lattice distortion within a specific temperature range (250-450℃). By leveraging the synergistic effect of the kinetic and thermal energy of a high-pressure hydrogen gas flow, it achieves simultaneous control of the physical crushing, chemical reduction, and crystal growth of coarse ammonium perrylate particles. The ultrafine grinding, dispersion, and in-situ reduction of ammonium perrylate are completed within a closed system.

[0007] The technical solution of the present invention is as follows: A one-step reduction method for preparing ultrafine graded high-purity rhenium powder, comprising the following steps: S1 will D 50 High-purity ammonium perrylate coarse particles >50μm are fed into a closed fluidized bed mill protected by high-purity hydrogen. S2 simultaneously performs pulsed airflow pulverization and reduction treatment on the high-purity ammonium perrylate coarse particles in the closed fluidized bed airflow mill, that is, the high-purity ammonium perrylate coarse particles are reduced in a pulsed airflow, the pulsed airflow being a pulsed airflow of high-purity hydrogen, with a pressure of 1.5-3 MPa and a pulse frequency of 5-20 Hz; the reduction treatment includes: holding at 200-300℃ for 0.5-1.5 h, followed by holding at 350-450℃ for 1-3 h.

[0008] The inventors unexpectedly discovered that, compared to airflow milling using continuous steady-state airflow, this method employs pulsed high-pressure hydrogen airflow. This not only achieves ultrafine grinding of materials to micron or nanometer scale, avoiding media contamination associated with mechanical ball milling, but also utilizes the immense shear force instantaneously generated by the pulsed shock wave (whose impact energy is 1.5-2 times that of ordinary steady-state airflow) to specifically disrupt the tetragonal crystal structure of ammonium rhenium oxide, directly fracturing large particles into nanoscale crystal nuclei, thus avoiding the accumulation of lattice defects caused by prolonged grinding. Based on this, this method can obtain high-purity ultrafine rhenium powder through a one-step reduction process within an integrated sealed device.

[0009] The inventors unexpectedly discovered that in the reduction process of the present invention, the first stage temperature is 200-300℃. At this temperature, ammonium perrylate undergoes a deamination reaction, and the crystal volume expands by about 15%, reaching a critical point of brittleness, making it extremely easy to be broken by the pulsed gas flow; the second stage temperature is 350-450℃, which allows the following reduction reaction to immediately occur on the surface of the broken fine ammonium perrylate particles: 2NH4ReO4 + 7H2 → 2Re + 8H2O + 2NH 3。

[0010] The inventors unexpectedly discovered that in the preparation method of the present invention, the pulsed airflow pulverization and reduction treatment can produce a significant synergistic effect. During the pulsed airflow pulverization process, the airflow velocity is above 300 m / s, and the airflow kinetic energy can continuously strip away the water vapor and ammonia generated in the reaction, preventing the formation of a passivation film on the surface of rhenium particles. At the same time, by utilizing the high surface mobility of rhenium atoms at high temperature during the reduction treatment, they can be rapidly arranged into a dense hexagonal crystal structure, realizing in-situ pulverization and reduction, and obtaining rhenium powder with small grains, stable structure and high dispersion.

[0011] The above preparation method of the present invention utilizes the effect that the brittle fracture energy of ammonium permanganate in a hydrogen atmosphere is much lower than that of air or other inert gases (such as argon), so that hydrogen gas can simultaneously act as a reducing agent and a breaking medium, thereby simultaneously realizing the breaking and in-situ reduction of ammonium permanganate. The broken particles produced by this method of breaking and reducing at the same time have fresh interfaces, large specific surface areas, and fast reduction reaction rates.

[0012] According to some preferred embodiments of the present invention, the one-step reduction preparation method further includes: performing a classification process after the pulsed airflow pulverization and reduction treatment, wherein the classification process includes: classifying the rhenium powder particles obtained by pulsed airflow pulverization and reduction treatment by a high-speed rotating classifying wheel disposed in the closed fluidized bed airflow mill, wherein the ultrafine rhenium powder is collected in a collection system and the remaining rhenium powder is returned to the closed fluidized bed airflow mill.

[0013] According to some preferred embodiments of the present invention, the rotational speed of the high-speed rotating grading wheel is 3000-8000 rpm.

[0014] According to some preferred embodiments of the present invention, the particle size D of the ultrafine rhenium powder is... 50 It ranges from 1 to 10 μm.

[0015] According to some preferred embodiments of the present invention, the process of implementing the high-purity hydrogen protection includes: introducing high-purity hydrogen into the grinding chamber of the closed fluidized bed mill to replace the air therein; the dew point of the high-purity hydrogen is below -60°C and the oxygen content is <10ppm.

[0016] According to some preferred embodiments of the present invention, the flow rate of the high-purity hydrogen gas is 1-10 L / min.

[0017] According to some preferred embodiments of the present invention, the closed fluidized bed air jet mill is equipped with a heating jacket, a pulse valve and a ceramic liner; before the pulse air jet mill is performed, the cavity and transport pipeline of the closed fluidized bed air jet mill are preheated to 200-500°C.

[0018] According to some preferred embodiments of the present invention, the purity of the high-purity hydrogen is 99.999%.

[0019] The present invention further provides ultrafine graded high-purity rhenium powder prepared according to the above one-step reduction preparation method.

[0020] This ultrafine grade of high-purity rhenium powder has a purity of ≥99.995%, an O content of less than 500 ppm, and a D content of ≥99.995%. 50 It is ≤10μm.

[0021] According to some preferred embodiments of the present invention, the D of the ultrafine graded high-purity rhenium powder 50 ≤5μm, loose packing density of 3-5g / cm³, purity ≥99.995%, and O content less than 500 ppm.

[0022] The present invention has the following beneficial effects: (1) The preparation method of the present invention can be carried out in a closed hydrogen environment without the need for ball milling media, thus avoiding the introduction of metal impurities (Fe, Cr, Ni, etc.), preventing material oxidation, and significantly improving product purity. (2) The preparation method of the present invention can combine the three processes of crushing, reduction and further classification into one, and use physical energy to assist chemical reaction, which significantly shortens the process flow and improves the preparation efficiency. At the same time, it eliminates the intermediate transfer process and further avoids impurity contamination. (3) The preparation method of the present invention can combine the new surface generated by crushing with the hydrogen reduction and heating process. By utilizing the high-energy surface generated at the moment of crushing, the activation energy of the reduction reaction is reduced, and rapid reduction can be achieved at a relatively low temperature of 200-450℃, replacing the traditional high-temperature reduction of 900℃, and increasing the reaction rate by more than 3 times, significantly reducing energy consumption and shortening the production cycle. (4) The present invention can prepare high-purity micro-nano rhenium powder with narrow particle size distribution and good flowability, which is suitable for direct pressing and molding. Attached Figure Description

[0023] Figure 1 Here is a SEM image of the rhenium powder prepared in Example 1; Figure 2The image shows the SEM morphology of the rhenium powder prepared in Comparative Example 1. Figure 3 The image shows the SEM morphology of the rhenium powder prepared in Comparative Example 2. Figure 4 The diagram shows the structure of the equipment used in the embodiment. In the diagram: 1-drive motor, 2-fine powder discharge and collection device, 3-grading impeller, 4-heating and heat preservation components, 5-loading chamber, 6-pulse device, 7-coarse powder collection device. Detailed Implementation

[0024] The technical solutions of the present invention will be further described below with reference to the embodiments and accompanying drawings. The embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0025] The equipment used in the following examples is a laboratory-grade fluidized bed air jet mill, and its simplified structural diagram is attached. Figure 4 As shown, the fluidized bed air mill includes a loading chamber 5 containing a ceramic liner, i.e., a grinding chamber; a drive motor 1 located at the top of the loading chamber 5; the drive motor 1 connected to a classifying impeller 3 via a transmission shaft to perform high-speed rotation to separate and crush powder within the loading chamber 5; heating and insulation components 4, such as a heating jacket, are arranged around the loading chamber 5 to raise the temperature of the grinding chamber inside the equipment; a pulse device 6 is provided on the lower side of the loading chamber 5 to provide pulsed airflow, which is connected to the loading chamber 5 via a pulse valve; a coarse powder collection device 7 is provided at the bottom of the loading chamber 5 to collect incompletely crushed coarse powder, so as to achieve repeated grinding and crushing; and a fine powder discharge and collection device 2 is provided on the upper side of the loading chamber 5 for fine powder collection and gas separation.

[0026] In the following embodiments, the bulk density was determined by a Hall flow meter, the particle size was determined by a laser particle size analyzer, the impurity oxygen content was determined by infrared absorption method, and the purity was tested by glow discharge mass spectrometry (GDMS). In accordance with the nonferrous metal industry standard YS / T 1017-2015, 30 impurity elements involved were detected to obtain the purity of the main element Re.

[0027] Example 1 Ultrafine high-purity rhenium powder is prepared through the following process: S1. Nitrogen gas is introduced into the grinding chamber of the fluidized bed mill equipped with a heating jacket, pulse valve and ceramic liner to replace the internal air for 30 minutes. Then, high-purity hydrogen gas with a purity of 99.999%, dew point ≤ -60℃ and oxygen content ≤ 1ppm is introduced through a normal gas flow pipe at a flow rate of 5L / min. After 30 minutes of introduction, a continuous and steady-state hydrogen gas flow is formed in the grinding chamber. The hydrogen gas pressure is 0.7-0.8MPa. The steady-state hydrogen gas flow is continuously introduced, and then step S2 is performed. S2: After turning on the heating jacket and raising the grinding chamber temperature to 250℃, open the pulse gas flow valve to introduce pulsed hydrogen gas flow. The pressure of the introduced pulsed hydrogen gas is 2.0MPa, and the pulse frequency is 10Hz. Add 500g of high-purity ammonium rhenium oxide particles with a purity ≥99.99% and a particle size of 75μm into the grinding chamber for the first stage of crushing and reduction, which lasts for 1 hour. Then, raise the temperature to 400℃ for the second stage of crushing and reduction, which lasts for 1 hour. The pulse frequency remains unchanged during both stages of crushing and reduction. After the second stage of crushing and reduction in S3, the stage impeller is activated to achieve staged separation. The stage impeller speed is 3000 rpm. S4 After the materials have been graded and separated, collect the rhenium powder obtained.

[0028] The obtained high-purity rhenium powder was tested using the following methods: average particle size and particle size distribution span were measured using a laser particle size analyzer; loose density was measured using a Hall effect flow meter; purity was tested using a GDMS method; and O content was determined using infrared absorption spectroscopy. The test results showed that the obtained product was dark gray, with D... 50 The particle size is 1.5 μm, with a particle size distribution spanning 1-3; the loose packing density is 4.2 g / cm³, the purity is 99.995%, and the O content is less than 500 ppm.

[0029] The SEM images of the obtained rhenium powder are attached. Figure 1 As shown, the microstructure of the obtained rhenium powder is mainly fragmented and dendritic, and the shape is regular and the dispersion is uniform.

[0030] Comparative Example 1 High-purity rhenium powder is prepared through the following process: S1. Nitrogen gas is introduced into the grinding chamber of the fluidized bed mill equipped with a heating jacket, pulse valve and ceramic liner to replace the internal air for 30 minutes. Then, high-purity hydrogen gas with a purity of 99.999%, dew point ≤ -60℃ and oxygen content ≤ 1ppm is introduced through a normal gas flow pipe at a flow rate of 5L / min. After 30 minutes of introduction, a continuous and steady-state hydrogen gas flow is formed in the grinding chamber. The hydrogen gas pressure is 0.7-0.8MPa. The steady-state hydrogen gas flow is continuously introduced, and then step S2 is performed. S2 turns on the heating jacket and raises the grinding chamber temperature to 250°C. Then, 500g of high-purity ammonium perrylate particles with a purity ≥99.99% and a particle size of 75μm are added to the grinding chamber for the first stage of crushing and reduction for 1 hour. Then, the temperature is raised to 400°C for the second stage of crushing and reduction for 1 hour. After the second-stage crushing and reduction of S3, the classifying impeller is activated to achieve classification and separation. The speed of the classifying impeller is set to 3000 rpm. S4 After the materials have been graded and separated, collect the rhenium powder obtained.

[0031] The obtained rhenium powder was tested using the following methods: average particle size and particle size distribution span were measured using a laser particle size analyzer; loose density was measured using a Hall effect flow meter; purity was tested using a GDMS method; and O content was determined using infrared absorption spectroscopy. The test results showed that the obtained product was dark gray, with D... 50 The particle size is 3.5 μm, with a particle size distribution span of 3-5; the loose packing density is 2.8 g / cm³, the purity is 99.992%, and the O content is 800-900 ppm.

[0032] The SEM images of the obtained rhenium powder are attached. Figure 2 As shown, the obtained powder contains a large amount of unreacted ammonium perrylate sandwich structure, which is tightly coated.

[0033] Comparative Example 2 Rhenium powder is prepared through the following process: S1. Nitrogen gas is introduced into the grinding chamber of the fluidized bed mill equipped with a heating jacket, pulse valve and ceramic liner to replace the internal air for 30 minutes. Then, high-purity hydrogen gas with a purity of 99.999%, dew point ≤ -60℃ and oxygen content ≤ 1ppm is introduced through a normal gas flow pipe at a flow rate of 5L / min. After 30 minutes of introduction, a continuous and steady-state hydrogen gas flow is formed in the grinding chamber. The hydrogen gas pressure is 0.7-0.8MPa. The steady-state hydrogen gas flow is continuously introduced, and then step S2 is performed. At room temperature, the pulse gas flow valve is opened to introduce pulse hydrogen gas flow. The pressure of the introduced pulse hydrogen gas is 2.0 MPa and the pulse frequency is 10 Hz. 500g of high-purity ammonium rhenium granules with a purity ≥99.99% and a particle size of 75μm are added into the grinding chamber and pulse gas flow crushing is carried out directly. The pulse frequency remains unchanged during the crushing process. S3 activates the classifier impeller for classification and separation, and sets the classifier impeller speed to 3000 rpm; After the material is graded and separated, the crushed fine ammonium rhenium powder is collected and loaded into a pure molybdenum boat. It is then placed in a tube furnace for two reduction treatments. During the reduction treatment, hydrogen gas with a flow rate of 5 L / min is introduced as the carrier gas. The temperature of the first reduction treatment is 300℃ and the time is 4 h. The temperature of the second reduction treatment is 750℃ and the time is 4 h. After that, the rhenium powder is collected.

[0034] The obtained rhenium powder was tested using the following methods: average particle size and particle size distribution span were measured using a laser particle size analyzer; loose density was measured using a Hall effect flow meter; purity was tested using a GDMS method; and O content was determined using infrared absorption spectroscopy. The test results showed that the obtained product was dark gray, with D... 50 The particle size is 10.5 μm, with a particle size distribution spanning 5-10; the loose packing density is 2.80 g / cm³. 3 The purity is 99.978%, and the O content is 1200-1400ppm.

[0035] The SEM images of the obtained rhenium powder are attached. Figure 3 As shown, the obtained powder has an irregular shape, a rough surface, and a porous, hollow interior.

[0036] The detection results of Example 1 are compared with those of Comparative Examples 1 and 2 in Table 1 below: Table 1. Rhenium powder test results Average particle size (D50) 1.5 μm 3.5 μm 10.5 μm Laser particle size analyzer Particle size distribution span Narrow (1-3) Wider (3-5) Width (5-10) <![CDATA[Span=(D 90 −D 10) / D 50 ]]> Loose packing density 3.5 g / cm³ 2.8 g / cm³ 2.0 g / cm³ Hall effect current meter purity 99.995% 99.992% 99.978% GDMS O content (ppm) <500 ppm 800-900 ppm 1200-1400 ppm Infrared absorption method Production cycle Approximately 8 hours (one-step method) Approximately 8 hours (one-step method) Approximately 16 hours (step-by-step method) - It should be noted that the above descriptions are merely preferred embodiments of the present invention and should not limit the scope of protection of the technical solutions of the present invention. Any modifications made to the technical solutions described in the foregoing embodiments, or equivalent substitutions of technical features, by those skilled in the art within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A one-step reduction preparation method for ultrafine graded high-purity rhenium powder, characterized in that, It includes the following steps: S1 will D 50 High-purity ammonium perrylate coarse particles >50μm are fed into a closed fluidized bed mill protected by high-purity hydrogen. S2 simultaneously performs pulsed airflow pulverization and reduction treatment on the high-purity ammonium perrylate coarse particles in the closed fluidized bed airflow mill, that is, the high-purity ammonium perrylate coarse particles are reduced in a pulsed airflow, the pulsed airflow being a pulsed airflow of high-purity hydrogen, with a pressure of 1.5-3 MPa and a pulse frequency of 5-20 Hz; the reduction treatment includes: holding at 200-300℃ for 0.5-1.5 h, followed by holding at 350-450℃ for 1-3 h.

2. The one-step reduction preparation method according to claim 1, characterized in that, It also includes: a classification process after the pulsed airflow pulverization and reduction treatment, wherein the classification process includes: classifying the rhenium powder particles obtained by the pulsed airflow pulverization and reduction treatment by a high-speed rotating classifying wheel set in the closed fluidized bed airflow mill, wherein the ultrafine rhenium powder is collected in a collection system and the remaining rhenium powder is returned to the closed fluidized bed airflow mill.

3. The one-step reduction preparation method according to claim 2, characterized in that, The high-speed rotating grading wheel rotates at a speed of 3000-8000 rpm.

4. The one-step reduction preparation method according to claim 2, characterized in that, The particle size D of the ultrafine rhenium powder 50 It ranges from 1 to 10 μm.

5. The one-step reduction preparation method according to claim 1, characterized in that, The process of implementing the high-purity hydrogen protection includes: introducing high-purity hydrogen into the grinding chamber of the closed fluidized bed mill to replace the air therein; the dew point of the high-purity hydrogen is below -60℃ and the oxygen content is <10ppm.

6. The one-step reduction preparation method according to claim 5, characterized in that, The flow rate of the high-purity hydrogen is 1-10 L / min.

7. The one-step reduction preparation method according to claim 1, characterized in that, The closed fluidized bed air jet mill is equipped with a heating jacket, a pulse valve, and a ceramic liner; before the pulse air jet mill is pulverized, the cavity and transport pipeline of the closed fluidized bed air jet mill are preheated to 200-500°C.

8. The one-step reduction preparation method according to claim 1, characterized in that, The purity of the high-purity hydrogen is 99.999%.

9. A type of ultrafine graded high-purity rhenium powder, characterized in that, It is prepared by the one-step reduction preparation method according to any one of claims 1-8.

10. The ultrafine graded high-purity rhenium powder according to claim 9, characterized in that, Its D 50 ≤5μm, loose packing density of 3-5g / cm³, purity ≥99.995%, and O content less than 500ppm.

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