Preparation method of high-purity rhenium powder

Abstract

The application discloses a preparation method of high-purity rhenium powder and belongs to the field of metal processing. The method is used for preparing a final product through one-stage gradient high-temperature reduction treatment and two-stage low-temperature reduction treatment. The method has the advantages of simple production process, simple manual operation steps, low energy consumption, high crystallinity of the produced product, low oxygen content and high purity (up to 4N or above).

Description

Technical Field

[0001] This invention relates to the field of metal processing, and more specifically to a method for preparing high-purity rhenium powder. Background Technology

[0002] Rhenium metal is a rare metal with high melting point, high density, high mechanical strength, and high chemical stability, and is widely used in aerospace, military, medical, and chemical industries. Currently, the main process for preparing rhenium powder is the reduction method, using ammonium perlite as raw material. After pretreatment such as ball milling and crushing, elemental rhenium powder is prepared by reduction with a reducing agent (usually hydrogen). However, most existing rhenium powder preparation processes have high temperature requirements and high energy consumption; at the same time, the operation steps are cumbersome, and byproducts are easily generated, resulting in products with high oxygen content and low purity. Summary of the Invention

[0003] Based on the deficiencies of existing technologies, the purpose of this invention is to provide a method for preparing high-purity rhenium powder. This method prepares the final product through a first-stage gradient high-temperature reduction treatment and a second-stage low-temperature reduction treatment. The method has a simple production process, simple manual operation steps, low energy consumption, and produces a product with high crystallinity, low oxygen content, and a purity of 4N or higher.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing high-purity rhenium powder includes the following steps:

[0006] (1) After crushing ammonium perrhenate powder, it is placed in a sintering mold with a filling height of ≤10mm. Then, under a hydrogen atmosphere, it is first subjected to a first gradient sintering treatment at 200-300℃, then the temperature is raised to 500-600℃ for a second gradient sintering treatment, and finally the temperature is raised to 850-950℃ for a third gradient sintering treatment to obtain crude rhenium powder; the flow rate of the hydrogen atmosphere is ≥5L / min;

[0007] (2) Place the crude rhenium powder in a sintering mold and keep the filling height ≤10mm, and then perform a second sintering treatment at 400~600℃ in a hydrogen atmosphere to obtain the high-purity rhenium powder; the flow rate of the hydrogen atmosphere is ≥5L / min.

[0008] To reduce the production difficulty and energy consumption of rhenium metal powder while improving the purity of the final product, the preparation method of the product described in this invention involves a pre-sintering treatment within three specific gradient temperature ranges after the ammonium perrhenate powder is crushed. During this treatment stage, the ammonium perrhenate is fully reduced without any intermediate gaps, thus preventing the generation of intermediate by-products and resulting in relatively high crystallinity of the rhenium metal powder. Subsequently, to further improve the purity of the product and reduce its oxygen content, the resulting crude rhenium powder undergoes a second-stage sintering at a temperature range of 400–600°C. The two-stage sintering is characterized by low set temperatures, low overall energy consumption, and a clear gradient within the set temperature ranges, simplifying manual operation and increasing production efficiency.

[0009] In the aforementioned process, the temperature range during gradient sintering is crucial. If not set properly, it is impossible to guarantee the sufficient reduction of rhenium powder in the first stage and the degree of impurity removal of rhenium powder in the second stage. At the same time, during the production process, the flow rate of hydrogen and the filling height of materials need to be specifically set; otherwise, under the aforementioned low-temperature process and simple operation, the purity index of the product may not be fully guaranteed.

[0010] Preferably, the purity of the ammonium perrhenate is ≥4N.

[0011] Using high-purity ammonium perrhenate to prepare the product of this invention can not only avoid the impact of impurities on the purity of the final product, but also improve the product yield and ensure production efficiency.

[0012] Preferably, the average particle size of the perrhenate ammonium powder after crushing is 50-100 μm.

[0013] Preferably, the sintering process in step (1) is carried out in a tube furnace.

[0014] Preferably, the sintering mold is a quartz boat, the length of which is 280-320 mm and the width is 100-150 mm.

[0015] Preferably, in step (1), the time for the first sintering treatment is 2 to 3 hours, the time for the second sintering treatment is 2.5 to 3.5 hours, and the time for the third sintering treatment is 6 to 8 hours.

[0016] More preferably, in step (1), the temperature of the first sintering treatment is 220-280°C and the time is 2.3-2.7h, the temperature of the second sintering treatment is 520-580°C and the time is 2.8-3.2h, and the temperature of the third sintering treatment is 880-920°C and the time is 6.5-7.5h.

[0017] In a sintering process, in addition to setting the range of gradient temperature range, the sintering time in different temperature ranges also needs to be matched accordingly. When the sintering time range under the above-mentioned preferred range is selected, the sintering process can not only ensure the reduction effect of ammonium perrhenate, but also ensure the best production efficiency and energy consumption, and improve the production cost-effectiveness of the product.

[0018] Preferably, the secondary sintering process in step (2) is carried out in a tube furnace.

[0019] Preferably, in step (2), the time for the secondary sintering process is 4 to 6 hours.

[0020] More preferably, in step (2), the temperature during the secondary sintering treatment is 450-550°C and the time is 4.5-5.5h.

[0021] Corresponding to the primary sintering stage, the main purpose of the secondary sintering stage is to reduce the content of impurity elements (especially oxygen) in the product. Choosing an appropriate sintering time can reduce the energy consumption and hydrogen consumption of sintering while ensuring sufficient impurity removal effect.

[0022] Preferably, the flow rate of the hydrogen atmosphere in steps (1) and (2) is 5 to 10 L / min.

[0023] In theory, the higher the flow rate of hydrogen atmosphere in the preparation process of high-purity rhenium powder described in this invention, the better the effect. However, excessive flow rate will not only waste raw materials, but also cause safety problems. By selecting the hydrogen atmosphere setting at the above-mentioned preferred flow rate, a balance can be achieved between raw material consumption and product quality.

[0024] The beneficial effects of this invention are that it provides a method for preparing high-purity rhenium powder. This method prepares the final product through a first-stage gradient high-temperature reduction treatment and a second-stage low-temperature reduction treatment. The method has a simple production process, simple manual operation steps, low energy consumption, and produces a product with high crystallinity, low oxygen content, and a purity of 4N or higher.

[0025] Instruction manual illustrations

[0026] Figure 1 The XRD pattern of the product prepared by the method for preparing high-purity rhenium powder according to the present invention (purple is the comparison standard card). Detailed Implementation

[0027] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0028] Example 1

[0029] An embodiment of the preparation method of high-purity rhenium powder according to the present invention includes the following steps:

[0030] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and subjected to a first gradient sintering treatment at 200℃ for 2h under a hydrogen atmosphere. Then it was subjected to a second gradient sintering treatment at 500℃ for 2.5h. Finally, it was subjected to a third gradient sintering treatment at 850℃ for 6h to obtain crude rhenium powder. The flow rate of the hydrogen atmosphere was 10L / min.

[0031] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 400°C for 4 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 10 L / min.

[0032] Example 2

[0033] An embodiment of the preparation method of high-purity rhenium powder according to the present invention includes the following steps:

[0034] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and subjected to a first gradient sintering treatment at 250℃ for 2.5h under a hydrogen atmosphere. Then the temperature was raised to 550℃ for a second gradient sintering treatment for 3h. Finally, the temperature was raised to 900℃ for a third gradient sintering treatment for 7h to obtain crude rhenium powder. The flow rate of the hydrogen atmosphere was 8L / min.

[0035] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 500°C for 5 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 8 L / min.

[0036] Example 3

[0037] An embodiment of the preparation method of high-purity rhenium powder according to the present invention includes the following steps:

[0038] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and subjected to a first gradient sintering treatment at 300℃ for 3h under a hydrogen atmosphere. Then the temperature was raised to 600℃ for a second gradient sintering treatment for 3.5h. Finally, the temperature was raised to 950℃ for a third gradient sintering treatment for 8h to obtain crude rhenium powder. The flow rate of the hydrogen atmosphere was 5L / min.

[0039] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 600°C for 6 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 5 L / min.

[0040] Example 4

[0041] The embodiment of the method for preparing high-purity rhenium powder according to the present invention differs from that of embodiment 1 only in that the powder filling height in steps (1) and (2) is 10 mm.

[0042] Example 5

[0043] The embodiment of the method for preparing high-purity rhenium powder according to the present invention differs from that of embodiment 1 only in that the powder filling height in steps (1) and (2) is 6 mm.

[0044] Comparative Example 1

[0045] A method for preparing high-purity rhenium powder, the method comprising the following steps:

[0046] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and sintered at 850℃ for 10.5h under a hydrogen atmosphere to obtain crude rhenium powder; the flow rate of the hydrogen atmosphere was 10L / min.

[0047] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 400°C for 4 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 10 L / min.

[0048] Comparative Example 2

[0049] A method for preparing high-purity rhenium powder, the method comprising the following steps:

[0050] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and subjected to a first gradient sintering treatment at 400℃ for 2h under a hydrogen atmosphere. Then the temperature was raised to 700℃ for a second gradient sintering treatment for 2.5h. Finally, the temperature was raised to 850℃ for a third gradient sintering treatment for 6h to obtain crude rhenium powder. The flow rate of the hydrogen atmosphere was 10L / min.

[0051] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 400°C for 4 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 10 L / min.

[0052] Comparative Example 3

[0053] A method for preparing high-purity rhenium powder, the method comprising the following steps:

[0054] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and subjected to a first gradient sintering treatment at 200℃ for 4.5h under a hydrogen atmosphere. Then the temperature was raised to 850℃ for a second gradient sintering treatment for 6h to obtain crude rhenium powder. The flow rate of the hydrogen atmosphere was 10L / min.

[0055] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 400°C for 4 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 10 L / min.

[0056] Comparative Example 4

[0057] A method for preparing high-purity rhenium powder, the method comprising the following steps:

[0058] (1) After crushing ammonium perrhenate powder with a purity of 4N to an average particle size of 75μm, it was placed in a quartz boat with a length of 300mm and a width of 130mm and the filling height was kept at about 8mm. Then it was placed in a tube furnace and subjected to a first gradient sintering treatment at 200℃ for 2h under a hydrogen atmosphere. Then it was subjected to a second gradient sintering treatment at 500℃ for 2.5h. Finally, it was subjected to a third gradient sintering treatment at 700℃ for 6h to obtain crude rhenium powder. The flow rate of the hydrogen atmosphere was 10L / min.

[0059] (2) Place the crude rhenium powder in a quartz boat of the same size as in step (1) and keep the filling height at 8 mm. Then place it in a tube furnace and sinter it at 400°C for 4 hours in a hydrogen atmosphere to obtain the high-purity rhenium powder. The flow rate of the hydrogen atmosphere is 10 L / min.

[0060] Comparative Example 5

[0061] An embodiment of a method for preparing high-purity rhenium powder differs from Embodiment 1 only in that the coarse rhenium powder is not subjected to the secondary sintering treatment described in step (2).

[0062] Comparative Example 6

[0063] An embodiment of a method for preparing high-purity rhenium powder differs from Example 1 only in that the powder filling height in steps (1) and (2) is 12 mm.

[0064] Comparative Example 7

[0065] An embodiment of a method for preparing high-purity rhenium powder differs from Example 1 only in that the flow rate of the hydrogen atmosphere in steps (1) and (2) is 3 L / min.

[0066] Example 1

[0067] To verify the quality of the product obtained by the preparation method of high-purity rhenium powder described in this invention, the GDMS method was used to analyze and detect the content of various impurity elements such as Al and As (where Al to Zn are elements required by industry standards) in the products obtained in each embodiment and comparative example. At the same time, the total content of each impurity element was calculated. Since the detection items are the same, only the detection results of all detected elements in Examples 1 to 3 are listed as shown in Table 1. Other embodiments and comparative examples are not described in detail, and only the total content results are listed as shown in Table 2. Meanwhile, the oxygen content in the product was tested using infrared spectroscopy, as shown in Table 2.

[0068] Table 1

[0069]

[0070]

[0071] Table 2

[0072]

[0073]

[0074] The test results show that the preparation methods described in each embodiment of the present invention can achieve high product quality at relatively low sintering temperatures and sintering times. The total content of the target impurities can be kept below 41 ppm, and the oxygen content can be kept below 1000 ppm, resulting in high product production cost-effectiveness. Specifically, the process mainly relies on a specific three-stage gradient reduction treatment and a subsequent low-temperature secondary reduction sintering treatment, while controlling the atmosphere flow rate and filling height of the powder during sintering. If the process conditions are not set properly, the expected results cannot be achieved, as shown in Comparative Examples 1 to 5. In Comparative Example 1, the process did not use a gradient setting during the first stage of sintering reduction; in Comparative Example 2, although a three-stage gradient interval was set, the interval range was not within the scope defined by the present invention; in Comparative Example 3, the gradient interval was set appropriately, but there were only two stages, and no intermediate transition sintering program was set; in Comparative Example 4, the temperature during the third gradient sintering treatment was too low, and the final product results were not ideal. The product described in Comparative Example 5 was not prepared using a secondary low-temperature sintering process for impurity removal, resulting in a high level of impurities and oxygen content. In Comparative Example 6, the powder packing height was too high, causing some of the powder at the bottom to be unable to be fully reduced. In Comparative Example 7, the hydrogen flow rate used as a reducing agent was too low, and the product could not be completely reduced and impurities removed under such mild sintering conditions.

[0075] The product obtained in Example 1 was subjected to XRD detection. The characteristic peaks of the product in the result spectrum corresponded one-to-one with the standard card, and the characteristic peaks were highly sharp, indicating that the product had high crystallinity and high purity.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for producing high purity rhenium powder, characterized by, The method comprises the following steps: (1) crushing ammonium perrhenate powder, placing the crushed ammonium perrhenate powder in a sintering mold and keeping the filling height of the sintering mold less than or equal to 10 mm, then performing first gradient sintering treatment at 200-300 ℃ under a hydrogen atmosphere, then performing second gradient sintering treatment at 500-600 ℃, and finally performing third gradient sintering treatment at 850-950 ℃, to obtain crude rhenium powder; the flow rate of the hydrogen atmosphere is greater than or equal to 5 L / min, the time for the first gradient sintering treatment is 2-3 h, the time for the second gradient sintering treatment is 2.5-3.5 h, and the time for the third gradient sintering treatment is 6-8 h; (2) placing the crude rhenium powder in a sintering mold and keeping the filling height of the sintering mold less than or equal to 10 mm, then performing secondary sintering treatment at 400-600 ℃ under a hydrogen atmosphere, to obtain the high-purity rhenium powder; the flow rate of the hydrogen atmosphere is greater than or equal to 5 L / min, and the time for the secondary sintering treatment is 4-6 h.

2. The method of claim 1, wherein the high purity rhenium powder is prepared by the steps of: The sintering treatment in step (1) is performed in a tube furnace; the sintering mold is a quartz boat, and the length of the quartz boat is 280-320 mm and the width of the quartz boat is 100-150 mm. ​ 3. The method of claim 1, wherein the high purity rhenium powder is prepared by the steps of: In step (1), the temperature for the first gradient sintering treatment is 220-280 ℃, and the time is 2.3-2.7 h; the temperature for the second gradient sintering treatment is 520-580 ℃, and the time is 2.8-3.2 h; and the temperature for the third gradient sintering treatment is 880-920 ℃, and the time is 6.5-7.5 h. ​ 4. The method of claim 1, wherein the high purity rhenium powder is prepared by the steps of: In step (2), the temperature for the secondary sintering treatment is 450-550 ℃, and the time is 4.5-5.5 h. ​ 5. The method of claim 1, wherein the high purity rhenium powder is prepared by the steps of: The flow rate of the hydrogen atmosphere in steps (1) and (2) is 5-10 L / min. ​

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