CN114653940B

CN114653940B - Method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering method

Info

Publication number: CN114653940B
Application number: CN202210303183.9A
Authority: CN
Inventors: 贾贤赏; 李曹兵; 贾坤乐; 王芦燕; 彭鹰; 张康
Original assignee: Bgrimm Advanced Materials Science & Technology Co ltd; BGRIMM Technology Group Co Ltd
Current assignee: Bgrimm Advanced Materials Science & Technology Co ltd; BGRIMM Technology Group Co Ltd
Priority date: 2022-03-25
Filing date: 2022-03-25
Publication date: 2022-10-28
Anticipated expiration: 2042-03-25
Also published as: CN114653940A

Abstract

The application relates to the technical field of metal purification, and particularly discloses a method for purifying high-purity rhenium by a hydrogen-vacuum two-step sintering method. The method comprises four steps of compression molding, presintering, high-temperature sintering and post-treatment; firstly, pressing and molding high-purity rhenium powder, then presintering in a hydrogen atmosphere, then sintering at a high temperature in a vacuum atmosphere, and finally performing post-treatment; and the high-purity rhenium obtained by the method is purified. The method for purifying high-purity rhenium by the hydrogen-vacuum two-step sintering method can obtain high-purity rhenium with less impurity content and higher purity.

Description

Method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering method

Technical Field

The application relates to the technical field of metal purification, in particular to a method for purifying high-purity rhenium by a hydrogen-vacuum two-step sintering method.

Background

Rhenium is a metal material with high melting point, high density and high hardness, and is widely applied to the industries of military industry, aerospace semiconductors and the like, for example, high-purity rhenium is used for preparing nickel-based single crystal superalloy blades for an aerospace engine, but the content of impurity elements in the high-purity rhenium has great influence on the purity and the service performance of the single crystal superalloy.

At present, the separation and purification methods for rhenium include a solvent extraction method, an ion exchange method, a liquid membrane method, a high-temperature sintering method and the like, although the solvent extraction method, the ion exchange method and the liquid membrane method can effectively separate and purify rhenium, the product obtained by purification is high-purity ammonium rhenate, the product cannot be directly used for melting single-crystal high-temperature alloys, and further purification is needed to obtain high-purity rhenium; the purity of the high-purity rhenium obtained by the reduction-sintering method is easily influenced by the sintering environment, and other metal, nonmetal and other impurities are easily introduced in the sintering process, so that the use effect of the high-purity rhenium is influenced, and the application range of the high-purity rhenium is limited.

Therefore, a sintering method capable of effectively removing impurities in high-purity rhenium and further improving the purity of the high-purity rhenium is urgently needed.

Disclosure of Invention

In order to further improve the purity of the high-purity rhenium, the application provides a method for purifying the high-purity rhenium by hydrogen-vacuum two-step sintering.

The application provides a method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering, which adopts the following technical scheme: a method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering specifically comprises the following steps:

(1) And (3) compression molding: pressing and molding high-purity rhenium powder, and placing the molded product in a sintering furnace;

(2) Pre-sintering: vacuumizing the sintering furnace, introducing hydrogen, raising the furnace temperature to the pre-sintering temperature when the hydrogen pressure is 103-106kPa, and keeping the temperature; the pre-sintering temperature is 1200-1300 ℃, and the heat preservation time is 0.5-1h;

(3) And (3) high-temperature sintering: pumping hydrogen out of the sintering furnace by using a vacuum pump, and continuously pumping vacuum until the vacuum degree in the furnace is 10 ^-3 -10 ^-4 Pa, raising the furnace temperature to a high-temperature sintering temperature and preserving the temperature; the high-temperature sintering temperature is 2200-2300 ℃, and the heat preservation time is 1-2h; (4) post-treatment: and cooling the sintering furnace and stopping vacuumizing to obtain the purified high-purity rhenium.

The application provides a method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering, which is characterized in that the high-purity rhenium with small impurity content is obtained by the steps of high-purity rhenium powder press forming, presintering in a hydrogen atmosphere, high-temperature sintering in a vacuum atmosphere, post-treatment and the like. The method provided by the application can reduce the introduction of impurities in the sintering process, so that the impurities in the high-purity rhenium are reduced, and the high-purity rhenium with higher purity is obtained.

In a specific embodiment, in the pre-sintering step, the pre-sintering temperature may be 1200 ℃, 1250 ℃, or 1300 ℃.

In a specific embodiment, in the pre-sintering step, the pre-sintering temperature may also be 1200 to 1250 ℃ or 1250 to 1300 ℃.

In a specific embodiment, in the high temperature sintering step, the high temperature sintering temperature may be 2200 ℃, 2250 ℃ or 2300 ℃.

In some specific embodiments, in the high-temperature sintering step, the high-temperature sintering temperature is 2200 to 2250 ℃ or 2250 to 2300 ℃.

According to the method, the pre-sintering temperature and the high-temperature sintering temperature are controlled within the ranges, so that gas impurities and low-melting-point volatile impurities in the high-purity rhenium can be effectively removed, new impurities cannot be introduced, the atmosphere in the furnace is always in a clean state, and the high-purity rhenium with less metal impurities and gas impurities is finally obtained.

Under the condition of lower temperature and hydrogen atmosphere, the oxygen content in the high-purity rhenium blank can be reduced by utilizing the reduction effect of hydrogen, so that the purity of the high-purity rhenium is improved; and the low-melting-point metal in the furnace at the stage is not volatilized, the sintering hydrogen atmosphere does not contain the low-melting-point metal, and the high-purity rhenium is not polluted.

High-temperature sintering is carried out on high-purity rhenium in a vacuum atmosphere, so that the high-purity rhenium is fully shrunk and gradually densified, and impurities such as C, N, O and the like in the high-purity rhenium can escape from the interior of the high-purity rhenium in vacuum and at high temperature, and the impurity content in the sintering vacuum atmosphere is greatly reduced. Meanwhile, low-melting-point metal impurities in the hearth can be pumped out after being evaporated in a high-vacuum environment, so that the purity of high-purity rhenium can be obviously improved.

Therefore, according to the method, the high-purity rhenium is firstly sintered at low temperature in the hydrogen atmosphere, then sintered at high temperature in the vacuum atmosphere, and finally subjected to post-treatment, so that impurities such as C, N, O, low-melting-point metals and the like in the high-purity rhenium can be effectively removed, and new impurities cannot be introduced in the sintering process. The method provided by the application can obviously reduce the impurity content in the high-purity rhenium, and further obtains the high-purity rhenium with higher purity.

Preferably, in the step of compression molding, the purity of the high-purity rhenium is more than or equal to 99.99%.

In the present application, by controlling the purity of high-purity rhenium before purification within the above range, high-purity rhenium having a lower impurity content and a higher purity can be obtained.

Preferably, in the pre-sintering step, the temperature rise rate of the pre-sintering is 150-250 ℃/h.

In a specific embodiment, in the pre-sintering step, the temperature rise rate of pre-sintering may be 150 ℃/h, 200 ℃/h or 250 ℃/h.

In some specific embodiments, in the pre-sintering step, the temperature rise rate of the pre-sintering may also be 150 to 200 ℃/h or 200 to 250 ℃/h.

In the application, the temperature rise rate of the pre-sintering in the pre-sintering step is controlled within the range, so that the temperature rise efficiency of the pre-sintering furnace can be the highest, meanwhile, the sufficient hydrogen reduction reaction time is provided, the oxygen content in the high-purity rhenium can be effectively reduced, and metal impurities in a hearth cannot be introduced in the sintering process at the temperature, so that the purity of the high-purity rhenium can be obviously improved.

Preferably, in the high-temperature sintering step, the temperature rise rate of the high-temperature sintering is 350-450 ℃/h.

In a specific embodiment, in the high-temperature sintering step, the temperature rise rate of the high-temperature sintering can be 350 ℃/h, 400 ℃/h or 450 ℃/h.

In some specific embodiments, in the high-temperature sintering step, the temperature rise rate of the high-temperature sintering may be 350 to 400 ℃/h or 400 to 450 ℃/h.

In this application, with the intensification rate control of high-temperature sintering in the high-temperature sintering step in above-mentioned within range, can make high-temperature sintering stove intensification efficiency maximize, make the sintering body progressively even compact not fracture simultaneously, and then effectively get rid of gas impurity and low melting point volatility impurity among the high-purity rhenium, in addition through slowly rising temperature and in time taking out of impurity and separating to make the atmosphere in the stove be in clean state all the time, finally obtain the high-purity rhenium that gas impurity is less, purity is higher.

The post-processing step of the present application includes a high temperature annealing process.

Preferably, in the post-treatment step, the temperature of the high-temperature annealing treatment is 1300-1500 ℃, and the heat preservation time is 1-2h.

In a specific embodiment, in the post-treatment step, the temperature of the high-temperature annealing treatment may be 1300 ℃, 1400 ℃ or 1500 ℃.

In some specific embodiments, in the post-treatment step, the temperature of the high-temperature annealing treatment may also be 1300 to 1400 ℃ or 1400 to 1500 ℃.

In the application, the temperature of the high-temperature annealing treatment in the post-treatment step is controlled to be 1300-1500 ℃, and the high-temperature annealing treatment is kept at the temperature for 1-2 hours, so that residual impurities in the high-purity rhenium can be further pumped away, and the purity of the obtained high-purity rhenium is higher.

Preferably, in the pre-sintering step, the hydrogen flow of the introduced hydrogen is 2-6m ³ /h。

In summary, the present application has the following beneficial effects:

1. the method for purifying the high-purity rhenium by hydrogen-vacuum two-step sintering is adopted to sequentially perform the steps of compression molding, pre-sintering, high-temperature sintering, post-treatment and the like on the high-purity rhenium, so that the impurity content in the high-purity rhenium is effectively reduced, and the high-purity rhenium is obtained; the process method is simple to operate, low in energy consumption, short in purification time, free of organic matters, and capable of improving purity, saving energy and protecting environment.

2. According to the method for purifying the high-purity rhenium by hydrogen-vacuum two-step sintering, the high-purity rhenium with excellent quality is obtained by controlling the parameters such as the purity of the high-purity rhenium powder, the temperature rise rate and the pre-sintering temperature of the pre-sintering, the temperature rise rate and the high-temperature sintering temperature of the high-temperature sintering, the annealing temperature in the post-treatment step and the like, wherein the purity of the high-purity rhenium is more than or equal to 99.998%, the O content is less than or equal to 25ppm, the C content is less than or equal to 5ppm, and the N content is less than or equal to 10ppm.

Detailed Description

The application provides a method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering, which specifically comprises the following steps:

(1) And (3) pressing and forming: pressing high-purity rhenium powder with the purity of more than or equal to 99.99 percent into a cylindrical green body, and placing the cylindrical green body in a sintering furnace;

(2) Pre-sintering: vacuumizing the sintering furnace until the vacuum degree is 4-10Pa, closing a vacuum valve, and introducing hydrogen into the sintering furnace with the hydrogen flow of 2-6m ³ When the hydrogen pressure is 103-106kPa, then raising the furnace temperature to 1200-1300 ℃ at the temperature rise rate of 150-250 ℃/h, and preserving the heat for 0.5-1h at the temperature;

(3) And (3) high-temperature sintering: after the pre-sintering is finished, closing the hydrogen charging valve, pumping away the hydrogen in the sintering furnace by using a vacuum pump, and continuously pumping vacuum until the vacuum degree in the furnace is 10 ^-3 -10 ^-4 Pa, then raising the furnace temperature to 2200-2300 ℃ at the heating rate of 350-450 ℃/h, and preserving the temperature for 1-2h at the temperature;

(4) And (3) post-treatment: and after the high-temperature sintering is finished, reducing the temperature in the sintering furnace to 1300-1500 ℃, preserving the heat for 1-2h at the temperature, finally reducing the temperature to room temperature, and stopping vacuumizing to obtain the purified high-purity rhenium.

The starting materials and other test materials used in the following examples are all commercially available.

The present application will be described in further detail below with reference to examples 1 to 19, comparative examples 1 to 9, and test results.

Examples

Examples 1 to 3

Examples 1-3 each provide a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The above embodiments differ in that: the pre-sintering temperature in the pre-sintering step is specifically shown in table 1.

The hydrogen-vacuum two-step sintering process for purifying high purity rhenium provided in the above examples 1-3 comprises the steps of:

(1) And (3) compression molding: pressing 10kg of high-purity rhenium powder with the purity of 99.99 percent into a cylindrical green compact, and placing the cylindrical green compact into a sintering furnace; (2) pre-sintering: vacuumizing the sintering furnace until the vacuum degree is 8Pa, closing a vacuum valve, and sinteringIntroducing hydrogen into the furnace, wherein the hydrogen flow is 4m ³ When the hydrogen pressure is 105kPa, raising the furnace temperature to the pre-sintering temperature at the temperature rise rate of 200 ℃/h, and preserving the heat for 1h at the temperature;

(3) And (3) high-temperature sintering: after the pre-sintering is finished, closing the hydrogen charging valve, pumping away the hydrogen in the sintering furnace by using a vacuum pump, and continuously pumping vacuum until the vacuum degree in the furnace is 10 ^-4 Pa, then raising the furnace temperature to 2250 ℃ at the temperature rise rate of 400 ℃/h, and preserving the temperature for 1.5h at the temperature;

(4) And (3) post-treatment: and after the high-temperature sintering is finished, reducing the temperature in the sintering furnace to 1400 ℃, preserving the heat for 2 hours at the temperature, finally reducing the temperature to room temperature, and stopping vacuumizing to obtain the purified high-purity rhenium.

Table 1 presintering temperatures in the processes provided in examples 1-3

Examples 4 to 7

Examples 4-7 each provide a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The above embodiment differs from embodiment 2 in that: the temperature increase rate of the preliminary sintering in the preliminary sintering step is specifically shown in table 2.

TABLE 2 temperature ramp rates for presintering in examples 2 and 4-7

Examples	Rate of temperature rise (. Degree. C./h)
		2	200
4	100
		5	150
6	250
		7	300

Examples 8 to 9

Examples 8-9 each provide a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The above embodiment differs from embodiment 2 in that: the high-temperature sintering temperature in the high-temperature sintering step is specifically shown in table 3.

TABLE 3 high sintering temperatures in the methods of examples 2, 8-9

Examples 10 to 13

Examples 10-13 provide a hydrogen-vacuum two-step sintering process for purifying high purity rhenium, respectively.

The above embodiment is different from embodiment 2 in that: the temperature increase rate of the high-temperature sintering in the high-temperature sintering step is specifically shown in table 4.

TABLE 4 temperature increase Rate for high-temperature sintering in example 2 and examples 10 to 13

Examples 14 to 17

Examples 14-17 provide a hydrogen-vacuum two-step sintering process for purifying high purity rhenium, respectively.

The above embodiment differs from embodiment 2 in that: the temperature for the annealing treatment in the post-treatment step is specifically shown in table 5.

TABLE 5 holding temperature for annealing treatment in example 2 and examples 14 to 17

Examples	Insulation temperature (. Degree. C.)
		2	1400
14	1200
		15	1300
16	1500
		17	1600

Example 18

Example 18 provides a method for purifying high purity rhenium by hydrogen-vacuum two-step sintering.

The above embodiment is different from embodiment 2 in that: and (4) keeping the temperature in the pre-sintering step.

In example 18, the soak time in the pre-sintering step was 0.5h.

Example 19

Example 19 provides a method for purifying high purity rhenium by hydrogen-vacuum two-step sintering.

The above embodiment differs from embodiment 2 in that: and (4) keeping the temperature in the high-temperature sintering step.

In example 19, the soak time in the high temperature sintering step was 1 hour.

Comparative example

Comparative examples 1 to 2

Comparative examples 1-2 each provide a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The comparative example described above differs from example 2 in that: the pre-sintering temperature in the pre-sintering step is specifically shown in table 6.

Table 6 presintering temperature in the processes provided in example 2 and comparative examples 1-2

Comparative examples 3 to 4

Comparative examples 3-4 provide a method for purifying high purity rhenium by hydrogen-vacuum two-step sintering, respectively.

The comparative example described above differs from example 2 in that: the high-temperature sintering temperature in the high-temperature sintering step is specifically shown in table 7.

TABLE 7 high temperature sintering temperatures in the processes provided in example 2 and comparative examples 3-4

Comparative example 5

Comparative example 5 provides a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The comparative example described above differs from example 2 in that: and (4) keeping the temperature in the pre-sintering step.

In comparative example 5, the holding time in the pre-sintering step was 3 hours.

Comparative example 6

Comparative example 6 provides a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The comparative example described above differs from example 2 in that: and (4) keeping the temperature in the high-temperature sintering step.

In comparative example 6, the holding time in the high-temperature sintering step was 3 hours.

Comparative example 7

Comparative example 7 provides a method for purifying high purity rhenium by a hydrogen-vacuum two-step sintering.

The comparative example described above differs from example 2 in that: the purity of the high-purity rhenium powder in the pressing and forming step.

In comparative example 7, the purity of the high purity rhenium powder of the press-forming step was 99.97%.

Comparative example 8

Comparative example 8 provides a hydrogen-vacuum two-step sintering process for purifying high purity rhenium.

The comparative example described above differs from example 2 in that: and (5) post-processing.

In comparative example 8, the post-treatment was carried out by the following specific steps: and after the high-temperature sintering is finished, the temperature in the sintering furnace is reduced to room temperature, and the purified high-purity rhenium can be obtained.

Comparative example 9

Comparative example 9 provides a method for preparing high purity rhenium, comprising the following steps:

firstly, respectively taking 40-mesh and 80-mesh high-purity rhenium powder with the purity of 99.95%, and mixing the powder according to the weight ratio of 40-mesh: mixing at 80 mesh = 2; then mixing the mixed high-purity rhenium powder with high-purity alcohol (the purity is 99.5%) according to the proportion of 3; after cooling, the blank is calcined at high temperature, the hydrogen flow is 0.5L/min, the sintering temperature is 1800 ℃, and the sintering time is 8h; and after sintering, cooling along with the furnace to obtain high-purity rhenium.

Performance detection

High-purity rhenium was prepared by the methods provided in examples 1-19 and comparative examples 1-9, and the purity and impurity content of each high-purity rhenium were examined.

The impurity detection method comprises the following steps: detecting the contents of O and N impurities in the high-purity rhenium by using an oxygen-nitrogen analyzer; and detecting the content of the C impurity of the high-purity rhenium by using a carbon-sulfur analyzer.

The high purity rhenium purity was calculated by the metal impurity content. The detection of the metal impurity content of the high-purity rhenium adopts a glow discharge mass spectrometer, and the calculation method of the purity of the high-purity rhenium is as follows:

high purity rhenium purity =100% -metal impurity content.

The purity and impurity content detection results of the high-purity rhenium are shown in table 8:

TABLE 8 results of examining purity and impurity content of high-purity rhenium obtained in examples 1 to 19 and comparative examples 1 to 9

According to the detection results of the examples 1-19, the method for purifying the high-purity rhenium by the hydrogen-vacuum two-step sintering can obviously reduce the content of metals and other impurities in the high-purity rhenium, so that the high-purity rhenium is obtained.

Combining the detection results of the examples 1-3 and the comparative examples 1-2, it can be known that, with the increase of the pre-sintering temperature, the purity of the high-purity rhenium shows a trend that the purity is increased firstly and then decreased, and the contents of the impurities O and C in the high-purity rhenium show a trend that the impurities are decreased firstly and then increased; therefore, in the embodiments 1 to 3 of the present application, the high-purity rhenium with high purity can be obtained by controlling the sintering temperature of the pre-sintering to be between 1200 ℃ and 1300 ℃, and the purity of the high-purity rhenium is more than or equal to 99.998%; especially in example 2, when the sintering temperature is 1250 ℃, the purity of the high-purity rhenium is 99.9982%. Therefore, the method for purifying the high-purity rhenium through the hydrogen-vacuum two-step sintering can reduce the impurity content in the high-purity rhenium and further improve the purity of the high-purity rhenium.

Comparing the detection results of example 2 and examples 4-7, it can be seen that in the methods provided in examples 2 and 4-7, high-purity rhenium with small impurity content and high purity can be obtained by controlling the temperature rise rate of the pre-sintering step to be between 100-300 ℃/h; further comparison shows that in examples 2 and 5-6, the purity of the high-purity rhenium is higher by controlling the temperature rise rate of the pre-sintering step to be between 150 ℃/h and 250 ℃/h, and the purity of the high-purity rhenium is more than or equal to 99.9981 percent. Therefore, the temperature rise rate of the pre-sintering step is controlled to be 150-250 ℃/h, so that the impurity content in the high-purity rhenium can be effectively reduced, and the high-purity rhenium with higher purity and lower impurity content is obtained.

Combining the detection results of example 2, examples 8-9 and comparative examples 3-4, it can be seen that, in the vacuum atmosphere, the contents of O and C impurities in the high-purity rhenium tend to decrease and then increase with the increase of the high-temperature sintering temperature, and the purity of the high-purity rhenium tends to increase and then decrease. And the impurity contents of the high-purity rhenium obtained by the methods provided in example 2 and examples 8-9 are lower than those of the high-purity rhenium obtained by the methods provided in comparative examples 3-4. Therefore, the high-temperature sintering temperature is controlled between 2200 and 2300 ℃, and the high-purity rhenium obtained has less impurity content and higher purity.

As can be seen from the results of comparing examples 2 and 10 to 13, in the methods provided in examples 2 and 10 to 13, high purity rhenium having small impurity contents of O and C and high purity can be obtained by controlling the temperature increase rate of the high temperature sintering step to be 200 to 400 ℃/h; further comparison shows that in the methods provided by the examples 2 and 11-12, the purity of the high-purity rhenium obtained by controlling the temperature rise rate of the high-temperature sintering step to be 250-350 ℃/h is higher, and the purity of the high-purity rhenium is more than or equal to 99.9981%. Therefore, it is demonstrated that the present application can obtain high purity rhenium with high purity and low impurity content by controlling the temperature rise rate of the pre-sintering step to be between 250 and 350 ℃/h.

As can be seen from the results of comparing example 2 and examples 14 to 17, the high purity rhenium obtained by the methods provided in examples 2 and 14 to 17 has a low content of O and C impurities and a high purity; further comparison shows that the purity of the high-purity rhenium obtained by the methods provided by the example 2 and the examples 15 to 16 is more than or equal to 99.9981 percent. Therefore, the application shows that in the post-treatment step, the temperature of the annealing treatment is controlled between 1300 ℃ and 1500 ℃, and high-purity rhenium with smaller impurity content and higher purity can be obtained.

Comparing the results of the tests of example 2, example 18, and comparative example 5, it can be seen that the purity of the high purity rhenium obtained by the method provided in example 2 is higher than that obtained by the method provided in comparative example 5, indicating that extending the soak time for pre-sintering decreases the purity of the high purity rhenium. Therefore, the application controls the holding time in the pre-sintering step within the range of 0.5-1h, and can obtain high-purity rhenium with low impurity content and high purity.

As can be seen from the results of comparing examples 2, 19 and 6, the purity of the high purity rhenium obtained by the methods provided in examples 2 and 19 is higher than that of the high purity rhenium obtained by the method provided in comparative example 6, which indicates that the purity of the high purity rhenium is decreased by increasing the holding time for the high temperature sintering. Therefore, the heat preservation time in the high-temperature sintering step is controlled within the range of 1-2h, and high-purity rhenium with low content of O and C impurities and high purity can be obtained.

According to the detection results of comparative example 7 and example 2, the purity of the high-purity rhenium obtained by the method provided by comparative example 7 is 99.9963%; while the purity of the high purity rhenium obtained from the process provided in example 2 was 99.9982%. Therefore, when the purity of the high-purity rhenium powder in the compression molding step is more than or equal to 99.99 percent, the obtained high-purity rhenium has less O and C impurity content and higher purity.

According to the detection results of the example 2 and the comparative example 8, the purity of the high-purity rhenium obtained by the method provided by the comparative example 8 is obviously lower than that of the high-purity rhenium obtained by the method provided by the example 2, and the high-temperature annealing treatment of the high-purity rhenium can obviously improve and reduce the impurity content of the high-purity rhenium and improve the purity of the high-purity rhenium.

As can be seen by combining the test results of examples 1-19 and comparative example 9, the impurity content of the high-purity rhenium obtained by the method for purifying the high-purity rhenium by hydrogen-vacuum two-step sintering provided by examples 1-19 of the present application is significantly lower than that of the high-purity rhenium prepared by the preparation method of the high-purity rhenium provided by comparative example 9, and the purity of the high-purity rhenium obtained by examples 1-19 is significantly higher than that of the high-purity rhenium obtained by comparative example 9. Thus. The method for purifying the high-purity rhenium by using the hydrogen-vacuum two-step sintering can reduce impurities in the high-purity rhenium, and further improve the purity of the high-purity rhenium.

In summary, the present application provides a method for purifying high purity rhenium by hydrogen-vacuum two-step sintering; controlling the temperature of the pre-sintering junction within the range of 1200-1300 ℃; the temperature rising rate of the pre-sintering is controlled within the range of 150-250 ℃/h; the high-temperature sintering temperature is controlled between 2200 and 2300 ℃; the temperature rise rate of the high-temperature sintering is controlled between 350 and 450 ℃/h; the temperature of the annealing treatment is controlled between 1300 ℃ and 1500 ℃, the purity of the obtained high-purity rhenium is more than or equal to 99.998 percent, the O content is less than or equal to 25ppm, the C content is less than or equal to 5ppm, and the N content is less than or equal to 10ppm.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, it is intended that all such modifications and alterations be included within the scope of this invention as defined in the appended claims.

Claims

1. A method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering is characterized by comprising the following steps:

(1) And (3) pressing and forming: pressing and molding high-purity rhenium powder, and placing the molded product in a sintering furnace;

(2) Pre-sintering: sequentially vacuumizing the sintering furnace, introducing hydrogen, raising the furnace temperature to the pre-sintering temperature when the hydrogen pressure is 103-106kPa, and preserving the temperature; the pre-sintering temperature is 1200-1300 ℃, and the heat preservation time is 0.5-1h;

(3) And (3) high-temperature sintering: pumping out hydrogen from the sintering furnace by using a vacuum pump, and continuously pumping vacuum until the vacuum degree in the furnace is 10 ^-3 -10 ^-4 Pa, raising the furnace temperature to a high-temperature sintering temperature and preserving the temperature; the high-temperature sintering temperature is 2200 to 2300 ℃, and the heat preservation time is 1 to 2 hours;

(4) And (3) post-treatment: carrying out high-temperature annealing treatment on the sintering furnace, wherein the temperature of the high-temperature annealing treatment is 1300-1500 ℃, and the heat preservation time is 1-2h; and finally, cooling and stopping vacuumizing to obtain the purified high-purity rhenium.

2. The method for purifying high-purity rhenium through hydrogen-vacuum two-step sintering as claimed in claim 1, wherein the purity of the high-purity rhenium powder in the step of press forming is greater than or equal to 99.99%.

3. The method for purifying high purity rhenium by hydrogen-vacuum two-step sintering as claimed in claim 1, wherein the temperature rise rate of the pre-sintering in the pre-sintering step is 150-250 ℃/h.

4. The method for purifying high purity rhenium by hydrogen-vacuum two-step sintering as claimed in claim 1, wherein the temperature rise rate of the high temperature sintering in the high temperature sintering step is 350-450 ℃/h.

5. The method for purifying high purity rhenium by hydrogen-vacuum two-step sintering as claimed in claim 1, wherein the flow rate of the hydrogen gas in the pre-sintering step is 2-6m ³ /h。

6. The method for purifying high-purity rhenium by hydrogen-vacuum two-step sintering according to any one of claims 1 to 5, characterized in that in the post-treatment step, the purity of the purified high-purity rhenium is more than or equal to 99.998%, the O content is less than or equal to 25ppm, the C content is less than or equal to 5ppm, and the N content is less than or equal to 10ppm.