Preparation method of 6N high-purity rhenium powder

Abstract

The invention discloses a preparation method of 6N high-purity rhenium powder, and belongs to the technical field of high-purity metal purification. According to the method disclosed by the invention, high-efficiency separation of rhenium and impurities is realized by performing'primary hydrogen reduction-two-stage oxidation-secondary hydrogen reduction 'on crude ammonium rhenate, and 6N and above high-purity rhenium powder is prepared. Compared with the prior art, the method can effectively solve the key technical problem that impurity elements in ammonium rhenate are not thoroughly removed. Meanwhile, the requirement for preparation equipment of the 6N high-purity rhenium powder is low, operation is easy, the overall reaction is relatively sealed, cation exchange resin is not introduced, and secondary pollution of impurities and loss of rhenium are avoided. The purity of the rhenium powder prepared through the method is larger than or equal to 99.9999%, and the rhenium powder is stable in quality and easy to popularize.

Description

Technical Field

[0001] The invention belongs to the technical field of high-purity metal purification, and specifically designs a method for preparing 6N high-purity rhenium powder. Background Art

[0002] Rhenium is a rare metal that is mainly associated with molybdenite and bornite. Copper concentrate is used as a raw material for copper smelting production, and generally contains 3-50g / t of rhenium. Under high temperature conditions of pyrometallurgy, rhenium in copper concentrate is oxidized to generate gaseous Re 2 O 7 Entering the flue gas purification system, after being washed with dilute acid to obtain ReO 4 Arsenic enters the copper smelting wastewater in the form of arsenic, and forms rhenium-arsenic filter cake through the sulfidation process. As a primary resource of rhenium, arsenic filter cake has the characteristics of high arsenic content and low rhenium content. Through the oxidation-reduction process, partial separation of arsenic and rhenium can be achieved to obtain a rhenium-arsenic solution.

[0003] At present, chemical precipitation, ion exchange and solvent extraction are the main methods for separating and enriching rhenium from rhenium-containing solutions. Chemical precipitation is to selectively precipitate rhenium in solution by utilizing the difference in solubility of rhenium and other coexisting ions in solution. Although the chemical precipitation method has a simple process and convenient operation, it consumes a large amount of chemical reagents and a large amount of waste residue produced as a byproduct is difficult to be effectively treated. Ion exchange is to use ion exchange resin to exchange ions with Re(VII) to achieve adsorption and separation of Re(VII) in solution. Ion exchange has the advantages of good selectivity and high separation efficiency, but it also has the disadvantages of expensive resin, difficult regeneration and difficult treatment of waste resin. Solvent extraction is to use organic solvent as extractant to extract Re(VII) in solution into organic solution, and then use stripping agent to strip Re(VII) in organic solvent to achieve separation and recovery of Re(VII) in solution. Solvent extraction has the advantages of high extraction and separation efficiency, simple process and low cost for Re(VII), so it is widely used in industry. However, high-purity ammonium rhenate cannot be obtained by extraction alone. Therefore, other processes need to be combined with the extraction process to deeply purify the ammonium rhenate solution and prepare high-purity ammonium rhenate.

[0004] The prior art discloses a method for crystallizing an ammonium rhenate solution, which is easy to operate, but the grade of the obtained ammonium rhenate is not high. There is also a method of treating smelting waste acid by pretreatment, centrifugal extraction, recrystallization, etc., which cannot control the process and has few optimized parameters, and the grade of the produced ammonium rhenate is only 3N ammonium rhenate. Alternatively, high-purity preparation of ammonium rhenate can be achieved by controlling the cooling temperature and time through multi-stage cooling, but this method requires a crude ammonium rhenate solution as a raw material, has high requirements for raw materials, and the prepared ammonium rhenate is mostly 3N ammonium rhenate, and multiple optimizations are required to obtain 4N ammonium rhenate.

[0005] CN111872409A discloses a production process for high-purity aviation-grade rhenium particles, but the total amount of impurities in this solution is still relatively large and cannot meet the requirements of 5N level or higher.

[0006] CN114309631A discloses a method for preparing rhenium powder, which comprises placing ammonium rhenate powder in a container, placing the container in a furnace, introducing dried and purified air, calcining, and obtaining rhenium oxide powder; then introducing hydrogen to reduce the rhenium oxide; then placing the hydrogen-reduced material together with the container in a vacuum furnace for hydrogen pulse reduction, and after the reduction is completed, maintaining the vacuum and utilizing the residual heat in the container for vacuum degassing; ultrasonically crushing and sieving the degassed rhenium powder to obtain finished rhenium powder. The preparation method of rhenium powder provided in the application has a purity of more than 99.9999%, a powder O content of ≤20PPm, a content of gas elements such as H, N, C, and P of ≤10PPm, and a powder particle size of 1 to 50μm. However, this method requires high vacuum operation, high equipment requirements, and large investment, which is not conducive to industrial production.

[0007] CN111285404A discloses a method for preparing high-purity rhenium heptoxide by gas reduction, which is to reduce crude ammonium rhenate to a low-valent rhenium compound under a reducing gas atmosphere and high temperature conditions, and then oxidize the low-valent rhenium compound under an oxygen atmosphere to obtain a high-valent rhenium oxide rhenium heptoxide that is easy to sublime. The method for preparing high-purity rhenium heptoxide of the present invention has a short process flow, a high reaction yield, and a high product purity. According to testing, the purity of the high-purity rhenium heptoxide product prepared by the inventive method is greater than 99.999%, and the rhenium recovery rate is greater than 98.5%. However, this method requires high-temperature reduction before oxidation, and the raw material adaptability is poor.

[0008] The purification methods of existing technology can only achieve 5N purity and cannot reach 6N purity. Summary of the invention

[0009] In order to overcome the problems in the background technology, the present invention provides a method for preparing 6N high-purity rhenium powder.

[0010] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0011] A method for preparing 6N high-purity rhenium powder comprises the following steps:

[0012] (1) heating crude ammonium rhenate under hydrogen to obtain crude rhenium powder;

[0013] (2) placing the coarse rhenium powder in an oxygen atmosphere for a first heating and heat preservation, and naturally cooling to room temperature to obtain a rhenium-containing vapor deposit on the container wall;

[0014] (3) heating and keeping the rhenium-containing vapor deposit in an oxygen atmosphere for a second time, and cooling naturally to room temperature to obtain rhenium heptoxide powder on the container wall;

[0015] (4) vacuum drying the rhenium heptoxide powder to obtain high-purity rhenium heptoxide powder;

[0016] (5) High-purity rhenium heptoxide powder is reduced at high temperature in a hydrogen atmosphere and finally cooled naturally to obtain 6N high-purity rhenium powder.

[0017] Preferably, in step (1), the heating and insulation temperature is 500-700°C, the hydrogen flow rate is 100-300 mL / min, the insulation time is 4-6 h, and the heating rate is 5-10°C / min.

[0018] Preferably, in step (2), the oxygen flow rate is 80-300 mL / min, the temperature of the first heating and insulation is 450-550° C., the time is 3-5 h, and the heating rate is 5-10° C. / min.

[0019] Preferably, in step (3), the oxygen flow rate is 30-60 mL / min, the temperature of the first heating and insulation is 350-450° C., the time is 3-5 h, and the heating rate is 5-10° C. / min.

[0020] The present invention performs two-stage oxidation on the crude rhenium powder after hydrogen reduction, and the first oxidation temperature is 450-550° C., the oxygen flow rate is 80-300 mL / min, and the second oxidation temperature is 350-450° C., the oxygen flow rate is 30-60 mL / min, so that the purity of the high-purity rhenium powder finally obtained can be guaranteed to reach 6N. Otherwise, the purity of the high-purity rhenium powder obtained is at the purity level of 5N.

[0021] The present invention can obtain high-purity rhenium heptoxide through two-stage oxidation processes at different temperatures and oxygen flow rates, ensure efficient separation of rhenium and impurity elements, and improve the purity of high-purity rhenium powder to 6N after hydrogen reduction. If only one long-term oxidation is performed, the purity of the obtained high-purity rhenium powder is difficult to reach the purity of 6N level.

[0022] Preferably, in step (4), the vacuum drying temperature is 100°C, the time is 8 hours, and the vacuum degree is -0.085 MPa.

[0023] Preferably, in step (5), the temperature of high temperature reduction is 700°C to 950°C, the time is 3 to 5 hours, and the heating rate is 5 to 10°C / min.

[0024] Preferably, the purity of the crude ammonium rhenate is 80-90%.

[0025] Preferably, the purity of the hydrogen is ≥99.9999%, and the purity of the oxygen is ≥99.9999%.

[0026] Beneficial effects of the present invention: The present invention realizes efficient separation of rhenium and impurities by sequentially subjecting crude ammonium rhenate to a process of one hydrogen reduction-two-stage oxidation-one hydrogen reduction, and prepares 6N and above high-purity rhenium powder. Compared with the prior art methods, this method can effectively solve the key technical problem of incomplete removal of impurity elements in ammonium rhenate; at the same time, the preparation equipment requirements for the 6N high-purity rhenium powder of the present invention are low, the operation is simple, the overall reaction is relatively sealed, and no cation exchange resin is introduced, thereby avoiding secondary contamination of impurities and loss of rhenium. The purity of the rhenium powder prepared by the method of the present invention is ≥99.9999%, the product quality is stable, and it is easy to promote. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] All chemical reagents not specified in the examples and comparative examples of the present invention were commercially available analytically pure for experiments.

[0029] Example 1

[0030] A method for preparing 6N high-purity rhenium powder comprises the following steps:

[0031] Primary reduction: Take 20g of crude ammonium rhenate with a purity of 86% and spread it evenly in a clean quartz boat, and put the quartz boat into a clean quartz tube. Hydrogen is introduced into the quartz tube with a hydrogen flow rate of 200mL / min. The crude ammonium rhenate is subjected to a period of impurity removal treatment. The treatment temperature is gradually increased from room temperature to 500°C at a heating rate of 8°C / min. It is reduced for 4h in a high-purity hydrogen atmosphere, and finally allowed to cool to room temperature to obtain crude rhenium powder.

[0032] Two-stage oxidation: Place crude rhenium powder in a reaction boat, place the reaction boat in a clean quartz tube, introduce oxygen into the tube and heat to 550°C to oxidize the metal rhenium powder. The heating rate is 5°C / min, the oxygen flow rate is 200mL / min, and the oxidation time is 4h. The rhenium heptoxide generated by the reaction sublimates and finally cools naturally to room temperature. After cooling, the rhenium heptoxide cools and condenses in another area, and the solid impurities remain in the reaction boat, thereby achieving effective separation of rhenium and impurities. Rhenium heptoxide was collected and placed in a clean quartz tube. Oxygen was introduced into the tube and heated to 350°C to oxidize the rhenium heptoxide powder. The heating rate was 5°C / min, the oxygen flow rate was 30 mL / min, and the oxidation time was 3 hours. Finally, it was naturally cooled to room temperature. The rhenium heptoxide was collected and ground with polytetrafluoroethylene for 45 minutes and then transferred to a vacuum drying oven. The vacuum degree was -0.085 MPa and the temperature was 100°C for 8 hours to finally obtain high-purity rhenium heptoxide powder.

[0033] Secondary reduction: evenly spread high-purity rhenium heptoxide powder in a clean rhenium boat with a thickness of 5 mm, then send the zirconium oxide boat into a clean high-purity quartz tube, introduce high-purity hydrogen, and perform hydrogen reduction at 850°C for 4 hours with a heating rate of 5°C / min. Then naturally cool to room temperature to obtain high-purity metallic rhenium powder with a purity of 99.999948%.

[0034] Example 2

[0035] The only difference between the method for preparing 6N high-purity rhenium powder in this embodiment and that in embodiment 1 is that:

[0036] In the first reduction: the reduction temperature is 600°C, the time is 3 hours, and the high-purity rhenium powder finally obtained has a purity of up to 99.999928%.

[0037] Example 3

[0038] The only difference between the method for preparing 6N high-purity rhenium powder in this embodiment and that in embodiment 1 is that:

[0039] In the two-stage oxidation: the first stage oxidation temperature is 500°C, and the second stage oxidation temperature is 400°C. The high-purity rhenium powder finally obtained has a purity of up to 99.999951%.

[0040] Example 4

[0041] The only difference between the method for preparing 6N high-purity rhenium powder in this embodiment and that in embodiment 1 is that:

[0042] In the secondary reduction: the reduction temperature is 950°C, and the high-purity rhenium powder finally obtained has a purity of up to 99.999965%.

[0043] Example 5

[0044] A method for preparing 6N high-purity rhenium powder comprises the following steps:

[0045] Primary reduction: Take 20g of crude ammonium rhenate with a purity of 80% and spread it evenly in a clean quartz boat, and put the quartz boat into a clean quartz tube. Hydrogen is introduced into the quartz tube with a hydrogen flow rate of 300mL / min. The crude ammonium rhenate is subjected to a period of impurity removal treatment. The treatment temperature is gradually increased from room temperature to 700°C at a heating rate of 5°C / min. It is reduced for 6h in a high-purity hydrogen atmosphere, and finally allowed to cool to room temperature to obtain crude rhenium powder.

[0046] Two-stage oxidation: Place crude rhenium powder in a reaction boat, place the reaction boat in a clean quartz tube, introduce oxygen into the tube and heat to 450°C to oxidize the metal rhenium powder. The heating rate is 5°C / min, the oxygen flow rate is 80mL / min, and the oxidation time is 5h. The rhenium heptoxide generated by the reaction sublimates and finally cools naturally to room temperature. After cooling, the rhenium heptoxide cools and condenses in another area, and the solid impurities remain in the reaction boat, thereby achieving effective separation of rhenium and impurities. Rhenium heptoxide was collected and placed in a clean quartz tube. Oxygen was introduced into the tube and heated to 450°C to oxidize the rhenium heptoxide powder. The heating rate was 5°C / min, the oxygen flow rate was 60 mL / min, and the oxidation time was 5 h. Finally, it was naturally cooled to room temperature. The rhenium heptoxide was collected and ground with polytetrafluoroethylene for 45 min, then transferred to a vacuum drying oven, dried at a vacuum degree of -0.085 MPa and a temperature of 100°C for 8 h, and finally high-purity rhenium heptoxide powder was obtained.

[0047] Secondary reduction: evenly spread high-purity rhenium heptoxide powder in a clean rhenium boat with a thickness of 5 mm, then send the zirconium oxide boat into a clean high-purity quartz tube, introduce high-purity hydrogen, and perform hydrogen reduction at 700°C for 5 hours with a heating rate of 5°C / min. Then naturally cool to room temperature to obtain high-purity metallic rhenium powder with a purity of 99.999923%.

[0048] Example 6

[0049] A method for preparing 6N high-purity rhenium powder comprises the following steps:

[0050] Primary reduction: Take 20g of crude ammonium rhenate with a purity of 99% and spread it evenly in a clean quartz boat, and put the quartz boat into a clean quartz tube. Hydrogen is introduced into the quartz tube with a hydrogen flow rate of 100mL / min. The crude ammonium rhenate is subjected to a period of impurity removal treatment. The treatment temperature is gradually increased from room temperature to 600°C at a heating rate of 10°C / min. It is reduced for 4h in a high-purity hydrogen atmosphere, and finally allowed to cool to room temperature to obtain crude rhenium powder.

[0051] Two-stage oxidation: Place crude rhenium powder in a reaction boat, place the reaction boat in a clean quartz tube, introduce oxygen into the tube and heat to 500°C to oxidize the metal rhenium powder. The heating rate is 10°C / min, the oxygen flow rate is 300mL / min, and the oxidation time is 3h. The rhenium heptoxide generated by the reaction sublimates by heat and finally cools naturally to room temperature. After cooling, the rhenium heptoxide cools and condenses in another area, and the solid impurities remain in the reaction boat, thereby achieving effective separation of rhenium and impurities. Rhenium heptoxide was collected and placed in a clean quartz tube. Oxygen was introduced into the tube and heated to 400°C to oxidize the rhenium heptoxide powder. The heating rate was 10°C / min, the oxygen flow rate was 50mL / min, the oxidation time was 4h, and finally it was naturally cooled to room temperature. The rhenium heptoxide was collected and ground with polytetrafluoroethylene for 45min and then transferred to a vacuum drying oven. The vacuum degree was -0.085MPa and the temperature was 100°C for 8h to finally obtain high-purity rhenium heptoxide powder.

[0052] Secondary reduction: evenly spread high-purity rhenium heptoxide powder in a clean rhenium boat with a thickness of 5 mm, then send the zirconium oxide boat into a clean high-purity quartz tube, introduce high-purity hydrogen, and perform hydrogen reduction at 800°C for 3 hours with a heating rate of 10°C / min. Then naturally cool to room temperature to obtain high-purity metallic rhenium powder with a purity of 99.999906%.

[0053] The high purity metal rhenium powder obtained in Examples 1-6 and the crude ammonium rhenate in Example 1 were subjected to GDMS detection. The results are shown in Table 1 below.

[0054] Table 1

[0055]

[0056]

[0057] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing 6N high-purity rhenium powder, characterized in that: The following steps are involved: (1) heating crude ammonium rhenate in a hydrogen atmosphere to obtain crude rhenium powder; (2) placing the coarse rhenium powder in an oxygen atmosphere for a first heating and heat preservation, and naturally cooling to room temperature to obtain a rhenium-containing vapor deposit on the container wall; (3) heating and keeping the rhenium-containing vapor deposit in an oxygen atmosphere for a second time, and cooling naturally to room temperature to obtain rhenium heptoxide powder on the container wall; (4) vacuum drying the rhenium heptoxide powder to obtain high-purity rhenium heptoxide powder; (5) High-purity rhenium heptoxide powder is reduced at high temperature in a hydrogen atmosphere and finally cooled naturally to obtain 6N high-purity rhenium powder.

2. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: In the step (1), the heating and insulation temperature is 500-700°C, the hydrogen flow rate is 100-300mL / min, the insulation time is 4-6h, and the heating rate is 5-10°C / min.

3. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: In the step (2), the oxygen flow rate is 80 to 300 mL / min, the temperature of the first heating and insulation is 450 to 550° C., the time is 3 to 5 hours, and the heating rate is 5 to 10° C. / min.

4. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: In the step (3), the oxygen flow rate is 30-60 mL / min, the second heating and insulation temperature is 350-450° C., the time is 3-5 h, and the heating rate is 5-10° C. / min.

5. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: In the step (4), the vacuum drying temperature is 100° C., the time is 8 h, and the vacuum degree is -0.085 MPa.

6. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: In the step (5), the temperature of high temperature reduction is 700°C to 950°C, the time is 3 to 5 hours, and the heating rate is 5 to 10°C / min.

7. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: The purity of the crude ammonium rhenate is 80-90%.

8. The method for preparing 6N high-purity rhenium powder according to claim 1, characterized in that: The purity of the hydrogen is ≥99.9999%, and the purity of the oxygen is ≥99.9999%.

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