Preparation method of high-purity metal vanadium
阅读说明：本技术 一种高纯金属钒的制备方法 (Preparation method of high-purity metal vanadium ) 是由 尹延西 江洪林 胡志方 袁学韬 于 2019-10-15 设计创作，主要内容包括：本发明公开了一种高纯金属钒的制备方法。该制备方法包括以下步骤：(1)以金属钒或钒合金为原料,以碘为介质,采用化学气相沉积法制得高纯金属钒结晶棒,其沉积基体为金属钒丝,反应过程中原料区域温度维持在600～1000℃之间,金属钒丝温度保持在1200～1500℃之间；(2)采用电子束熔炼法将高纯金属钒结晶棒熔炼成锭。本发明利用碘的特殊物理化学性质,以碘为介质,在化学气相沉积过程中能有效降低原料中的C、H、O、N杂质含量,并通过后续电子束熔炼,进一步降低较低饱和蒸汽压的金属杂质含量,最终获得低气体杂质含量的高纯金属钒锭。(The invention discloses a preparation method of high-purity metal vanadium. The preparation method comprises the following steps: (1) the method comprises the following steps of (1) preparing a high-purity metal vanadium crystal bar by using metal vanadium or vanadium alloy as a raw material and iodine as a medium and adopting a chemical vapor deposition method, wherein a deposition matrix of the high-purity metal vanadium crystal bar is a metal vanadium wire, the temperature of a raw material area is maintained between 600 and 1000 ℃ in the reaction process, and the temperature of the metal vanadium wire is maintained between 1200 and 1500 ℃; (2) and smelting the high-purity metal vanadium crystal rod into an ingot by adopting an electron beam smelting method. The method utilizes the special physical and chemical properties of iodine, takes the iodine as a medium, can effectively reduce the C, H, O, N impurity content in the raw materials in the chemical vapor deposition process, further reduces the metal impurity content with lower saturated vapor pressure through the subsequent electron beam melting, and finally obtains the high-purity metal vanadium ingot with low gas impurity content.)
1. The preparation method of the high-purity vanadium metal is characterized by comprising the following steps of:
(1) the method comprises the following steps of (1) preparing a high-purity metal vanadium crystal bar by using metal vanadium or vanadium alloy as a raw material and iodine as a medium and adopting a chemical vapor deposition method, wherein a deposition matrix of the high-purity metal vanadium crystal bar is a metal vanadium wire, the temperature of a raw material area is maintained between 600 and 1000 ℃ in the reaction process, and the temperature of the metal vanadium wire is maintained between 1200 and 1500 ℃;
(2) and smelting the high-purity metal vanadium crystal rod into an ingot by adopting an electron beam smelting method.
2. The method for preparing high-purity vanadium metal according to claim 1, wherein: before the chemical vapor deposition reaction, the reaction system adopts a gradient heating mode, the final temperature is not lower than 800 ℃, and the vacuum degree of the reaction system is higher than 1 multiplied by 10-1Pa。
3. The method for preparing high-purity vanadium metal according to claim 2, wherein: the heating mode of the reaction system is as follows: evacuating the reaction system when the vacuum degree is higher than 1X 10-1At Pa, starting to heat up and evacuate, starting from room temperature, setting multiple temperature gradients, and at each temperature gradient, maintaining vacuum degree higher than 1 × 10-1And when Pa, starting to heat to the next temperature gradient until the final temperature is reached.
4. The method for preparing high purity vanadium metal according to claim 2 or 3, wherein: when the temperature reaches the final temperature, iodine is added into the reaction system.
5. The method for preparing high-purity vanadium metal according to claim 1, wherein: the metal vanadium or vanadium alloy raw material is in a block shape, a granular shape, a chip shape or a powder shape.
6. The method for preparing high-purity vanadium metal according to claim 1, wherein: the diameter of the metal vanadium wire is 0.1-10 mm.
7. The method for preparing high-purity vanadium metal according to claim 1, wherein: in the chemical vapor deposition process, the temperature of a deposition matrix is characterized by a K value, wherein K is an empirical formula of voltage and current values: k ═ UI1/3Wherein U is a voltage value applied to the deposition substrate and has a unit of V; i is the value of the current through the deposition matrix in A; the K value is changed by adjusting the voltage and the current of the deposition matrix, so that the temperature of the deposition matrix is controlled and adjusted.
Technical Field
The invention relates to a preparation method of high-purity metal vanadium, belonging to the technical field of rare metal purification and preparation.
Background
The fast reactor (high-speed breeder) is a dominant reactor type of a fourth-generation advanced nuclear energy system, and can improve the utilization rate of natural uranium resources from about 1% of a pressurized water reactor to more than 60% due to the formation of closed circulation of nuclear fuel, and meanwhile, nuclear waste can be fully combusted, so that the emission of pollutants is reduced, the minimization of radioactive wastes is realized, and finally, the problems of waste and environmental pollution caused by the accumulation of a large amount of uranium-238 are solved. With the success of grid-connected power generation of the Chinese experimental fast reactor and the establishment and development of the future commercial fast reactor, huge material and element requirements and gaps are certainly brought, and meanwhile, the requirements on the impurity content of various materials, particularly the content of C, N, O, H and other gas impurities are higher and higher.
High-purity metal vanadium sectional materials and alloys thereof, such as V-15Ti-7.5Cr, V-15Cr-5Ti, V-10Ti, V-20Ti and the like, are one of important nuclear fusion, liquid metal cooling high-speed proliferation (fast neutron) reactor fuel rod coating and structure and heat dissipation materials due to the characteristics of high-temperature creep resistance, good dimensional stability, radiation induced expansion and damage resistance, high thermal conductivity, low thermal expansion coefficient and elastic modulus, small neutron absorption section, short isotope decay period, no strong decay product, excellent compatibility with liquid metal and alloys (such as uranium, sodium, lithium, lead-bismuth and the like) and the like. High-purity vanadium has also found a great deal of application in the fields of high-temperature superconducting materials (e.g., V3Ga alloy), and as an additive element in magnetic alloys (Fe-Cr-Co-V permanent magnets), non-magnetic hard alloys, titanium alloys, high-strength heat-resistant alloys, etc.
At present, the preparation method of high-purity vanadium metal is mainly divided into an electrolytic method and a thermal reduction-smelting method. Whether the electrolysis method or the thermal reduction-smelting method is adopted, the oxygen content of the prepared vanadium metal is mostly over 100ppm, and the N content is about tens of ppm, so that the properties and the application of the vanadium metal in fast reactors are greatly limited, and the reduction is urgently needed.
Disclosure of Invention
The invention aims to provide a preparation method of high-purity metal vanadium, which aims to solve the technical problem that the content of C, H, O, N and other gas impurities in the existing high-purity metal vanadium is still high and meet the application requirement of commercial fast reactor on low-gas-impurity-content high-purity metal vanadium in the future.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of high-purity vanadium metal comprises the following steps:
(1) the method comprises the following steps of (1) preparing a high-purity metal vanadium crystal bar by taking metal vanadium or vanadium alloy as a raw material and iodine as a medium and adopting a chemical vapor deposition method, wherein a deposition matrix is a metal vanadium wire, the temperature of a preferred raw material area in the reaction process is 600-1000 ℃, and the synthesis reaction rate of the iodine and the raw material is high at the temperature; the preferable temperature of the metal vanadium wire is 1200-1500 ℃, and the decomposition and deposition rate of vanadium iodide is higher at the temperature;
(2) and smelting the high-purity metal vanadium crystal rod into an ingot by adopting an electron beam smelting method.
In the chemical vapor deposition process, iodine vapor reacts with raw material metal vanadium to generate a large amount of volatile vanadium iodide vapor, the vanadium iodide vapor is volatilized and diffused to the hot vanadium wire to generate decomposition reaction, the generated metal vanadium is deposited and crystallized on the vanadium wire to enable the vanadium wire to continuously grow and become a high-purity metal vanadium crystal rod, and the generated iodine returns to the raw material area to continuously participate in synthesis reaction. The reaction formula is as follows:
the invention utilizes the special physical and chemical properties of iodine, takes the iodine as a medium, and can effectively reduce the C, H, O, N impurity content in the raw material in the chemical vapor deposition process. The main function of the subsequent electron beam melting is to further remove metal impurities with low saturated vapor pressure in the high-purity metal vanadium crystal rod prepared by the chemical vapor deposition method, thereby obtaining the high-purity metal vanadium ingot.
Before the chemical vapor deposition reaction, the reaction system adopts a gradient heating mode, the final temperature is not lower than 800 ℃, and the vacuum degree of the reaction system is higher than 1 multiplied by 10-1Pa. The heating mode of the reaction system is as follows: evacuating the reaction system when the vacuum degree is higher than 1X 10-1At Pa, starting to heat up and evacuate, starting from room temperature, setting multiple temperature gradients, and at each temperature gradient, maintaining vacuum degree higher than 1 × 10-1And when Pa, starting to heat to the next temperature gradient until the final temperature is reached.
When the temperature reaches the final temperature, iodine is added into the reaction system.
The chemical vapor deposition is carried out in a high vacuum reaction system, iodine is used as a reaction medium, and the chemical vapor deposition mainly has the following four impurities in the raw materials:
a) c, H, O, N, and carbide, nitride, and oxide impurities that do not react with iodine;
b) metallic impurities or non-metallic impurities which do not react with iodine at a set temperature;
c) impurities which react with iodine at a set temperature but do not generate volatile gas;
d) impurities which react with iodine at a set temperature but the generated volatile gas is not decomposed under a set condition.
In the present invention, the metal vanadium or vanadium alloy raw material may be in various forms such as a lump, a granule, a chip, and a powder.
In the invention, the diameter of the metal vanadium wire is 0.1-10 mm.
In the invention, in the chemical vapor deposition process, the temperature of a deposition matrix is characterized by adopting a K value, wherein K is an empirical formula of voltage and current values: k ═ UI1/3. Wherein U is a voltage value applied to the deposition substrate and has a unit of V; i is the value of the current through the deposition matrix in A. The K value is changed by adjusting the voltage and the current of the deposition matrix, so that the temperature of the deposition matrix is controlled and adjusted.
The invention has the advantages that:
the method utilizes the special physical and chemical properties of iodine, takes the iodine as a medium, can effectively reduce the C, H, O, N impurity content in the raw materials in the chemical vapor deposition process, further reduces the metal impurity content with lower saturated vapor pressure through the subsequent electron beam melting, and finally obtains the high-purity metal vanadium ingot.
According to the invention, by combining the chemical vapor deposition with the electron beam melting method, the impurity content in the existing metal vanadium can be obviously and effectively reduced, and the high-purity metal vanadium ingot with low impurity content of C, H, O, N can be prepared, so that the requirements of the fourth-generation commercial fast neutron reactor and other fields in the future can be met.
Detailed Description
The present invention is further illustrated by the following specific examples. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the present disclosure.
The preparation method of the high-purity vanadium metal specifically comprises the following steps:
(1) metal vanadium or vanadium alloy is filled into a reaction kettle and is paved on the furnace wall and the furnace bottom area; connecting the metal vanadium wire with a working electrode; loading iodine into an iodine feeder;
(2) connecting vacuum system, evacuating the reaction kettle when the vacuum degree is higher than 1 × 10-1At Pa, starting to heat up and evacuate, starting from room temperature, setting multiple temperature gradients, and maintaining vacuum degree higher than 1 × 10 at each temperature gradient-1At Pa, the temperature is increased to the next temperature gradient until the final temperature is higher than 1 × 10-1Pa；
(3) Applying current and voltage to the electrodes, observing the change of vacuum degree until the vacuum degree is higher than 1 × 10-1When Pa, the electrode power supply is closed;
(4) cooling the reaction kettle, opening an iodizer valve when the temperature of the raw material area is reduced to 600-1000 ℃, putting iodine into the reaction kettle, simultaneously applying a certain current and voltage to the electrode again, and controlling the temperature of the metal vanadium wire to be maintained within the range of 1200-1500 ℃;
(5) the reaction is started, the voltage and current values are adjusted during the reaction process, the K value is changed, the temperature of the metal vanadium wire is controlled and adjusted, and K is UI1/3。
(6) When the reaction rate is low, stopping the furnace, taking out the vanadium metal crystal rod after the furnace temperature is cooled to room temperature, and repeatedly washing and drying the residual raw materials for later use;
(7) and melting the metal vanadium crystal rod into an ingot by adopting an electron beam, thus obtaining the high-purity metal vanadium ingot.
Example 1
1) 25kg of dendritic vanadium (with the purity of 99.5%) is taken and put into a reaction kettle to cover the furnace wall and the furnace bottom area.
2) Taking a phi 3mm metal vanadium wire of 4m, and respectively connecting two ends with the electrodes.
3) 1kg of iodine is taken and put into an iodine adding device.
4) Connecting a vacuum system, and evacuating the reaction kettle. When the vacuum degree reaches 4.5 multiplied by 10-2When Pa, the temperature is raised to 250 ℃.
5) The temperature reaches 250 ℃ and the vacuum degree reaches 4.2 multiplied by 10-2When Pa, the temperature is raised to 500 ℃.
6) As step 5), setting a temperature gradient every 250 deg.C, every time the temperature reaches the set temperature, such as 500 deg.C, 750 deg.C, the vacuum degree reaches 5 × 10-2And when Pa is about, starting subsequent temperature rise.
7) When the temperature reaches 1000 ℃, the vacuum degree reaches 1.5 multiplied by 10-2And when Pa, turning off the heating power supply.
8) Applying current and voltage to the electrodes, observing the change of vacuum degree, and measuring the vacuum degree when the vacuum degree reaches 2.2 × 10-2And when Pa, the electrode power supply is closed.
9) When the temperature of the reaction kettle is reduced to 800 ℃, the valve of the iodine adding device is opened, and iodine is put into the reaction kettle.
10) And (3) starting an electrode power supply, and applying a certain current voltage to the electrode to maintain the temperature of the metal vanadium wire at about 1300 ℃.
11) The reaction starts. The temperature of the metal vanadium wire is controlled and adjusted by adjusting the voltage and the current value and changing the K value, wherein K is UI1/3。
12) When the reaction rate is low, the furnace is stopped. After the temperature of the reaction kettle is naturally cooled to room temperature, 3.1kg of high-purity metal vanadium crystal rods are taken out of the furnace. And repeatedly washing and drying the residual raw materials for later use.
13) And melting the vanadium metal crystal rod into an ingot by an electron beam. By GDMS full element analysis, the purity of the high-purity metal vanadium ingot reaches 99.95%, wherein the O content is 60ppm, the H content is less than 5ppm, the C content is 12ppm, and the N content is 20 ppm.
Example 2
1) 23kg of blocky vanadium-aluminum alloy (with the size of 2-30 mm and the vanadium content of about 90 percent) is taken and put into a reaction kettle to be paved on the furnace wall and the furnace bottom area.
2) Taking a metal vanadium wire with the diameter of 1.5mm to be 3.8m, and respectively connecting two ends of the metal vanadium wire with electrodes.
3) 800g of iodine is taken and put into an iodine adding device.
4) Connecting a vacuum system, and evacuating the reaction kettle. When the vacuum degree reaches 3.2 multiplied by 10-2And when Pa, heating to 300 ℃.
5) The temperature reaches 300 ℃ and the vacuum degree reaches 5.6 multiplied by 10-2When Pa, the temperature is raised to 650 ℃.
6) The temperature reaches 650 ℃, and the vacuum degree reaches 2.4 multiplied by 10-2When Pa, the temperature is raised to 1000 ℃.
7) The temperature reaches 1000 ℃, and the vacuum degree reaches 2.6 multiplied by 10-2And when Pa, turning off the heating power supply.
8) Applying current and voltage to the electrodes, observing the change of vacuum degree until the vacuum degree reaches 3.3 × 10-2And when Pa, the electrode power supply is closed.
9) When the temperature of the reaction kettle is reduced to 900 ℃, the valve of the iodine adding device is opened, and iodine is put into the reaction kettle.
10) And (3) starting an electrode power supply, and applying a certain current voltage to the electrode to maintain the temperature of the metal vanadium wire at about 1200 ℃.
11) The reaction starts. The temperature of the metal vanadium wire is controlled and adjusted by adjusting the voltage and the current value and changing the K value, wherein K is UI1/3。
12) When the reaction rate is low, the furnace is stopped. And after the temperature of the reaction kettle is naturally cooled to room temperature, taking out the reaction kettle, and taking out 2.86kg of high-purity metal vanadium crystal rods. And repeatedly washing and drying the residual raw materials for later use.
13) And melting the vanadium metal crystal rod into an ingot by an electron beam. By GDMS full element analysis, the purity of the high-purity metal vanadium ingot reaches 99.95%, wherein the O content is 57ppm, the H content is less than 5ppm, the C content is 18ppm, and the N content is 18 ppm.
Example 3
1) 30kg of scrap-shaped vanadium-aluminum alloy (the vanadium content is about 90 percent) is taken and put into a reaction kettle to be paved on the furnace wall and the furnace bottom area.
2) Taking a phi 4mm metal vanadium wire of 3.6m, and respectively connecting two ends with the electrodes.
3) 1.2kg of iodine is taken and put into an iodine adding device.
4) Connecting a vacuum system, and evacuating the reaction kettle. The vacuum degree reaches 1 x 10-1When Pa, the temperature is raised to 200 ℃.
5) The temperature reaches 200 ℃, and the vacuum degree reaches 2.1 multiplied by 10-2When Pa, the temperature is raised to 550 ℃.
6) The temperature reaches 550 ℃, and the vacuum degree reaches 2.9 multiplied by 10-2When Pa, the temperature is raised to 800 ℃.
7) The temperature reaches 800 ℃, and the vacuum degree reaches 3.4 multiplied by 10-2When Pa, the temperature is raised to 1100 ℃.
8) When the temperature reaches 1100 ℃, the vacuum degree reaches 1.3 multiplied by 10-2And when Pa, turning off the heating power supply.
9) Applying current and voltage to the electrodes, observing the change of vacuum degree until the vacuum degree reaches 2.6 × 10-2And when Pa, the electrode power supply is closed.
10) When the temperature of the reaction kettle is reduced to 850 ℃, the valve of the iodine adding device is opened, and iodine is put into the reaction kettle.
11) And (3) starting an electrode power supply, and applying a certain current voltage to the electrode to maintain the temperature of the metal vanadium wire at about 1400 ℃.
12) The reaction starts. The temperature of the metal vanadium wire is controlled and adjusted by adjusting the voltage and the current value and changing the K value, wherein K is UI1/3。
13) When the reaction rate is low, the furnace is stopped. After the temperature of the reaction kettle is naturally cooled to room temperature, 3.97kg of high-purity metal vanadium crystal rods are taken out of the furnace. And repeatedly washing and drying the residual raw materials for later use.
14) And melting the vanadium metal crystal rod into an ingot by an electron beam. By GDMS full element analysis, the purity of the high-purity metal vanadium ingot reaches 99.95%, wherein the O content is 64ppm, the H content is less than 5ppm, the C content is 15ppm, and the N content is 21 ppm.
The above examples of the present invention are merely illustrative of specific embodiments of the present invention and are not intended to limit the embodiments of the present invention. Any replacement or modification made by those skilled in the art within the technical scope of the present disclosure, which is based on the disclosure of the present invention and the spirit thereof, should be covered by the protection scope of the present invention.