Method for preparing vanadium metal through aluminothermy synergetic molten salt electrolysis

Abstract

The invention belongs to the field of vanadium metallurgy, and particularly relates to a method for preparing metal vanadium through aluminothermy in cooperation with molten salt electrolysis so as to solve the problem that in the prior art, the production cost of the metal vanadium is high due to the fact that high-temperature and high-vacuum refining is used for removing impurity aluminum. The method comprises the following steps: uniformly mixing a vanadium-containing raw material, metal aluminum and an additive according to a weight ratio of 100: (25-35): (4-8), igniting to carry out aluminothermic reduction reaction, and removing upper smelting slag after a reaction product is cooled to obtain primary metal vanadium; and the primary metal vanadium is subjected to molten salt electrolytic refining in the protective gas atmosphere, and refined metal vanadium is obtained. According to the method, high-temperature or high-vacuum refining is not needed, the high-purity metal vanadium can be prepared only through the two-step operation of aluminothermic reduction and molten salt electrolysis, and compared with an existing vanadium preparation process adopting high-temperature and high-vacuum refining, the energy consumption and the production cost are remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of vanadium metallurgy, and in particular relates to a method for preparing metallic vanadium by aluminothermic coordinated molten salt electrolysis. Background Art

[0002] Vanadium is an important rare metal element, accounting for 0.02wt% of the earth's crust. Vanadium and its alloys and compounds have excellent properties, so they are widely used. They play an important role in the fields of steel, aviation, chemical industry, biology, petroleum, non-ferrous metals, energy, construction, environmental protection, medical treatment, nuclear industry, etc., and occupy an important position in the national economy. Metal vanadium has been realized or has great application prospects in important fields such as aviation bearing steel, vanadium alloys for nuclear engineering, and vanadium-nickel alloy targets for integrated circuits. The requirements for the purity of metal vanadium in various fields are getting higher and higher.

[0003] The industrial method for preparing metallic vanadium is to prepare metallic vanadium of low purity by thermal reduction of vanadium oxide with other metals (such as calcium thermal reduction, aluminum thermal reduction, etc.), and then prepare metallic vanadium of higher purity by refining the crude vanadium.

[0004] Patent CN104894388A discloses a method for preparing vanadium target material by electron beam melting. The method uses irregular vanadium metal scraps such as rods and strips or vanadium aluminum alloy containing 90% vanadium as raw materials, melts them in an electromagnetic focused electron beam melting furnace, and uses a pull-down ingot. The pressure inside the furnace is 1x10 -1 -1x10 -3 Pa, the electron gun voltage is 25,000-30,000 volts, the current is 3-6 amperes, the diameter of the finished product is 100-150 mm, and the ingot length is 500-1300 mm. The purity of the product produced by this method can reach more than 99.95%, which can fully meet the demand for target materials for ion plating.

[0005] Patent CN102899510A discloses a method for producing high-purity metallic vanadium, which uses Al powder as a reducing agent and adopts an out-of-furnace smelting method to obtain a vanadium-aluminum alloy ingot; the surface of the vanadium-aluminum alloy ingot is cleaned and cut into vanadium-aluminum alloy bars of uniform shape, and the vanadium-aluminum alloy bars are welded by argon arc welding into vanadium-aluminum alloy rods matching the feed size of an electron beam melting furnace; the vanadium-aluminum alloy rods are fed into an electron beam melting furnace, evacuated, and the vanadium-aluminum alloy rods are bombarded with an electron beam flow to melt the vanadium-aluminum alloy rods and flow into a water-cooled crucible, where they are smelted in the melting zone of the water-cooled crucible, and the metallic vanadium liquid in the water-cooled crucible is cooled and solidified into a metallic vanadium ingot.

[0006] Patent CN110923476A discloses a three-step method for producing high-purity metal vanadium ingots. The method uses high-purity vanadium pentoxide and high-purity aluminum powder as raw materials, adopts vacuum aluminothermic method with argon protection to produce vanadium aluminum alloy containing about 90% vanadium, adopts horizontal electron beam melting furnace to melt into metal vanadium plate, removes some easily removable impurities such as aluminum, iron, chromium, etc., and continues to melt into metal vanadium column ingot in electron beam ingot casting furnace to further remove aluminum, iron, chromium, etc. impurities and impurities that are difficult to remove, and obtains high-purity metal vanadium ingot with vanadium content increased to more than 99.9%.

[0007] Patent CN117488105A discloses a method for preparing high-purity metallic vanadium, which comprises the following steps: uniformly mixing a vanadium-containing raw material, a reducing agent, and an additive in a ratio of 100:40~49:6~10, and then performing a metal thermal reduction reaction to obtain preliminary metallic vanadium; placing the preliminary metallic vanadium in an ultra-high temperature smelting furnace for smelting and refining, and cooling after smelting to obtain metallic vanadium; and subjecting the metallic vanadium to molten salt electrolytic refining to obtain high-purity metallic vanadium.

[0008] In the above method, when the metal vanadium is prepared by metal thermal reduction, the metal Al is sufficient to reduce the vanadium oxide, and Al is easy to combine with V to form a vanadium aluminum solid solution phase, such as Al2V3, AlV3, etc., which is difficult to remove later. In order to remove the vanadium aluminum solid solution phase, high temperature and high vacuum refining are required, which results in high energy consumption and cost for the preparation of metal vanadium.

[0009] Therefore, there is an urgent need in the art to develop a low-cost, low-energy method for preparing high-purity metallic vanadium. Summary of the invention

[0010] In view of this, in order to solve the problems existing in the prior art, the present invention provides a method for preparing metallic vanadium by thermite coordinated molten salt electrolysis.

[0011] The technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a method for preparing metallic vanadium by thermite-assisted molten salt electrolysis, the method comprising the following steps: Step S1: uniformly mixing the vanadium-containing raw material, metallic aluminum, and additives in a weight ratio of 100:25-35:4-8, igniting for aluminothermic reduction reaction, and after the reaction is completed and the product is cooled, removing the upper smelting slag to obtain primary metallic vanadium; Step S2: subjecting the primary metallic vanadium to molten salt electrolytic refining in a protective gas atmosphere to obtain refined metallic vanadium.

[0012] According to one embodiment of the present invention, the electrolytic cathode used in the molten salt electrolytic refining is selected from at least one of a molybdenum rod, a titanium rod, and a vanadium rod, and the electrolytic anode uses the primary metal vanadium.

[0013] According to one embodiment of the present invention, the molten salt electrolytic refining uses a graphite crucible as an electrolytic cell, a graphite sleeve with holes is provided in the graphite crucible, the porosity of the graphite sleeve is 10% to 60%, and the primary metal vanadium is placed between the graphite sleeve and the graphite crucible.

[0014] According to one embodiment of the present invention, the distance between the cathode and the graphite sleeve is 1-5 cm, and the cathode is horizontally aligned with the anode.

[0015] According to one embodiment of the present invention, the protective gas is selected from argon and / or helium.

[0016] According to one embodiment of the present invention, the cathode current density during molten salt electrolysis refining is controlled to be 0.01A / cm 2 ~0.4A / cm 2 .

[0017] According to one embodiment of the present invention, the molten salt system for molten salt electrolysis refining adopts NaCl-KCl-VCl X , where the molar ratio of NaCl to KCl is 1:1, VCl X The main component is VCl2.

[0018] According to one embodiment of the present invention, the vanadium-containing raw material is powdered vanadium pentoxide with a particle size of 0.05-1 mm, and in terms of mass percentage, V2O5≥99.95%, Fe≤0.01%, Si≤0.01%, and Cr≤0.01%.

[0019] According to one embodiment of the present invention, the particle size of the metal aluminum is 0.2-0.4 mm, and in terms of mass percentage, Al≥99.95%, Fe≤0.01%, Si≤0.01%, and Cr≤0.01%.

[0020] According to one embodiment of the present invention, the additive is mainly composed of aluminum oxide, and the particle size is 60-240 mesh.

[0021] The beneficial effects of the present invention include at least: The method for preparing metallic vanadium by aluminothermic coordinated molten salt electrolysis of the present invention optimizes the amount of aluminum in the aluminothermic reduction reaction, reduces the amount of metallic aluminum, so that there is excessive vanadium oxide around the metallic Al, promotes the combination of Al and O to form a stable oxide to inhibit the formation of the vanadium-aluminum solid solution phase, and then optimizes the molten salt electrolysis process to fully separate the oxide from the metallic vanadium, thereby preparing high-purity metallic vanadium. In this preparation process, high-temperature or high-vacuum refining is not required, and high-purity metallic vanadium can be prepared by only two steps of aluminothermic reduction and molten salt electrolysis. Compared with the existing vanadium preparation process using high-temperature and high-vacuum refining, energy consumption and production costs are significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A flow chart of a method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis provided in some embodiments of the present invention; Figure 2 It is a structural schematic diagram of the molten salt electrolytic cell refining equipment used in the present invention; Figure 3 The electron microscope image (Figure a), element distribution map (Figure b) and element content map (Figure c) of the primary metal vanadium obtained according to Example 2 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, the present invention provides a method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis, which generally comprises the following steps: Step S1: uniformly mixing the vanadium-containing raw material, metallic aluminum, and additives in a weight ratio of 100:25-35:4-8, igniting for aluminothermic reduction reaction, and after the reaction is completed and the product is cooled, removing the upper smelting slag to obtain primary metallic vanadium; Step S2: subjecting primary metallic vanadium to molten salt electrolytic refining in a protective gas atmosphere to obtain refined metallic vanadium.

[0026] In the above embodiment, the weight ratio of vanadium raw material to metal aluminum is 100:25-35. Compared with the conventional preparation process of vanadium oxide by aluminothermic reduction, the aluminum content of the present invention is lower, and by reducing the amount of metal aluminum, excessive vanadium oxide exists around metal Al, which promotes Al and O to combine to form a stable oxide to inhibit the formation of vanadium aluminum solid solution phase.

[0027] In some embodiments, the vanadium-containing raw material in step S1 is an oxide of vanadium, which can be selected from vanadium trioxide and / or vanadium pentoxide, and further selected from vanadium pentoxide. Vanadium pentoxide uses powdered vanadium pentoxide with a particle size of 0.05~1mm. The powdered vanadium pentoxide in this size range has a larger specific surface area, and its contact area with metallic aluminum is larger. In aluminothermic reduction, a larger contact area can promote the full reaction and mass transfer between vanadium pentoxide and aluminum, thereby improving the reaction efficiency. Moreover, the fine vanadium pentoxide particles are also easier to be infiltrated and reacted by metallic aluminum at high temperatures, further accelerating the reduction process. In addition, the powdered vanadium pentoxide particles have better heat and mass transfer properties, can transfer heat and reaction materials more evenly, avoid local overheating, and ensure that the reaction rates of various parts during the reaction are consistent. In terms of mass percentage, V2O5≥99.95%, Fe≤0.01%, Si≤0.01%, and Cr≤0.01% in vanadium pentoxide.

[0028] In some embodiments, the metal aluminum in step S1 uses aluminum particles with a particle size of 0.2~0.4mm, and in terms of mass percentage, Al≥99.95%, Fe≤0.01%, Si≤0.01%, and Cr≤0.01%. Compared with the conventional process for preparing metal vanadium by thermite reaction, the present invention has a lower aluminum content, which is intended to reduce the aluminum content in the primary metal vanadium, especially the amount of aluminum present in the vanadium-aluminum solid solution phase such as Al2V3 and AlV3. To this end, it is necessary to provide an excess of vanadium oxide around the metal Al, and Al and O are more likely to combine to form a stable compound. In order to allow excess vanadium oxide to exist around Al, the particle size of the aluminum particles needs to be controlled within a smaller range. In the present invention, the particle size of the aluminum particles is controlled to be 0.2~0.4mm.

[0029] In some embodiments, the main component of the additive in step S1 is alumina, and the smelting slag from the previous round of experiments can be crushed into particles with a particle size of 60-240 mesh and used as an additive. The additive is intended to balance the heat during the thermal reduction, avoid splashing due to excessive reaction, and reduce the yield of vanadium. Using smelting slag as an additive not only reduces the burden of solid waste treatment, but also realizes the recycling of resources, reducing production costs and environmental burdens.

[0030] In some embodiments, the ignition agent for thermite reduction in step S1 is magnesium powder, and the particle size of the magnesium powder is 160 mesh to 240 mesh. The combustion process of magnesium powder is relatively controllable, and the amount of ignition agent and ignition method can be adjusted as needed to achieve precise control of thermite reaction process.

[0031] In step S2, primary metal vanadium is subjected to molten salt electrolytic refining in a protective gas atmosphere to obtain refined metal vanadium. During the refining process, aluminum oxide in the form of oxide can be effectively separated from metal vanadium.

[0032] Figure 2 The schematic diagram of the structure of the molten salt electrolytic cell refining equipment used in step S2 is shown. The electrolytic cell uses a graphite crucible, and a graphite sleeve with holes is provided in the graphite crucible. The primary metal vanadium to be refined is placed between the graphite sleeve and the graphite crucible, so that the cathode and the anode are in a horizontally aligned position, and refined metal vanadium is obtained after molten salt electrolytic refining in a protective gas atmosphere.

[0033] In some embodiments, the electrolytic cathode in step S2 is selected from at least one of a molybdenum rod, a titanium rod, and a vanadium rod, and these materials have good electrical conductivity and corrosion resistance. The electrolytic anode uses primary metal vanadium. The electrolytic anode is connected to a graphite crucible, and the primary metal vanadium is placed between the graphite sleeve and the graphite crucible.

[0034] In some embodiments, the porosity of the graphite sleeve is 10% to 60%, and the distance between the cathode and the graphite sleeve is 1 to 5 cm, so that the crude metal vanadium (anode) can be fixed around the cathode, greatly increasing the effective area of ​​the electrode, and slightly increasing the distance between the cathode and the graphite sleeve so that the metal vanadium can have enough growth space.

[0035] In some embodiments, the shielding gas is selected from argon and / or helium.

[0036] In some embodiments, the cathode current density is controlled at 0.01A / cm during molten salt electrolytic refining. 2 ~0.4A / cm 2 .

[0037] The smooth progress of the electro-deoxidation reaction also has many requirements for the electrolyte. The electrolyte should have the advantages of low viscosity, good fluidity, and excellent conductivity. At the same time, the voltage drop of the electrolyte in the molten salt state should also be relatively small, which is conducive to the diffusion and migration of ions. The current efficiency of the electro-deoxidation reaction can be increased. In some embodiments, the molten salt system of the molten salt electrolytic refining of the present invention adopts NaCl-KCl-VCl X , where the molar ratio of NaCl to KCl is 1:1, VCl X The main component of molten salt is VCl2. There may be some VCl3 in the molten salt, because VCl2 is very unstable and can be easily oxidized to VCl3.

[0038] In order to further illustrate the technical solution and beneficial effects of the present invention, the present invention further provides specific embodiments: Example 1 With the goal of preparing metallic vanadium, 10 kg of vanadium pentoxide with a particle size of 0.05-0.1 mm, 2.5 kg of metallic aluminum with a particle size of 0.2-0.3 mm, and 0.4 kg of smelting slag with a particle size of 60 meshes were mixed evenly, put into a graphite crucible reaction vessel, and ignited by magnesium powder with a particle size of 160 meshes to cause a metal thermal reduction reaction. After the reaction was completed and the product was cooled, the upper smelting slag was removed to obtain primary metallic vanadium.

[0039] A primary metal vanadium block with a size of 0.5 cm is placed between a graphite sleeve and a graphite crucible. The opening rate of the graphite sleeve is 10%, and the distance between the molybdenum rod cathode and the graphite sleeve is 1 cm. Molten salt NaCl-KCl-VCl2 is added, and the molar ratio of NaCl to KCl is 1:1. The mass of the molten salt is 8% of the mass of the primary metal vanadium to be refined. In the protective gas Ar atmosphere, the cathode current density is controlled at 0.01A / cm 2 Molten salt electrolytic refining is carried out to obtain metallic vanadium.

[0040] After the above operation, the primary metal vanadium composition includes: V: 94.17%, Al: 0.426%, O: 3.72%, N: 0.082%, C: 0.017%, Fe: 0.018%, Si: 0.021%, Cr: 0.019%. The refined metal vanadium composition includes: V: 99.76%, Al: 0.01%, O: 0.032%, N: 0.011%, C: 0.018%, Fe: 0.014%, Si: 0.013%, Cr: 0.016%.

[0041] Example 2 With the goal of preparing metallic vanadium, 10 kg of vanadium pentoxide with a particle size of 0.05-0.5 mm, 3 kg of metallic aluminum with a particle size of 0.3-0.35 mm, and 0.6 kg of smelting slag with a particle size of 120 meshes were mixed evenly, put into a graphite crucible reaction vessel, and ignited by magnesium powder with a particle size of 200 meshes to cause a metal thermal reduction reaction. After the reaction was completed and the product was cooled, the upper smelting slag was removed to obtain primary metallic vanadium. Figure 3 The electron microscope image (Figure a), element distribution map (Figure b) and element content map (Figure c) of the primary metal vanadium obtained according to this embodiment are shown. It can be seen from the figure that most of the Al in the primary metal vanadium combines with O to form aluminum oxide, so that the elemental aluminum content in the matrix is ​​reduced to a lower level.

[0042] A 2cm-sized primary vanadium block is placed between a graphite sleeve and a graphite crucible. The opening rate of the graphite sleeve is 30%. The distance between the titanium rod cathode and the graphite sleeve is 3cm. Molten salt NaCl-KCl-VCl2 is added. The molar ratio of NaCl to KCl is 1:1. The mass of the molten salt is 10% of the mass of the primary vanadium to be refined. In the protective gas Ar atmosphere, the cathode current density is controlled at 0.25A / cm2 Molten salt electrolytic refining is carried out to obtain metallic vanadium.

[0043] After the above operation, the primary metal vanadium composition includes: V: 93.27%, Al: 0.479%, O: 4.72%, N: 0.042%, C: 0.025%, Fe: 0.024%, Si: 0.038%, Cr: 0.026%. The refined metal vanadium composition includes: V: 99.82%, Al: 0.014%, O: 0.021%, N: 0.009%, C: 0.009%, Fe: 0.018%, Si: 0.012%, Cr: 0.018%.

[0044] Example 3 With the goal of preparing metallic vanadium, 10 kg of vanadium pentoxide with a particle size of 0.5-1 mm, 3.5 kg of metallic aluminum with a particle size of 0.3-0.4 mm, and 0.8 kg of smelting slag with a particle size of 240 meshes were mixed evenly, put into a graphite crucible reaction vessel, and ignited by magnesium powder with a particle size of 240 meshes to cause a metal thermal reduction reaction. After the reaction was completed and the product was cooled, the upper smelting slag was removed to obtain primary metallic vanadium.

[0045] A 3cm-sized primary vanadium block is placed between a graphite sleeve and a graphite crucible. The opening rate of the graphite sleeve is 60%. The distance between the molybdenum rod cathode and the graphite sleeve is 5cm. Molten salt NaCl-KCl-VCl2 is added. The molar ratio of NaCl to KCl is 1:1. The mass of the molten salt is 12% of the mass of the primary vanadium to be refined. In the protective gas He atmosphere, the cathode current density is controlled at 0.4A / cm 2 Molten salt electrolytic refining is carried out to obtain metallic vanadium.

[0046] After the above operation, the primary metal vanadium composition includes: V: 94.63%, Al: 0.557%, O: 3.64%, N: 0.073%, C: 0.023%, Fe: 0.014%, Si: 0.018%, Cr: 0.021%. The refined metal vanadium composition includes: V: 99.71%, Al: 0.012%, O: 0.029%, N: 0.024%, C: 0.012%, Fe: 0.012%, Si: 0.011%, Cr: 0.017%.

[0047] Comparative Example 1 With the goal of preparing metallic vanadium, 10 kg of vanadium pentoxide with a particle size of 0.05-0.1 mm, 4.5 kg of metallic aluminum with a particle size of 0.5 mm, and 2.1 kg of smelting slag with a particle size of 180 meshes were mixed evenly, put into a graphite crucible reaction vessel, and ignited by magnesium powder with a particle size of 200 meshes to cause a metal thermal reduction reaction. After the reaction was completed and the product was cooled, the upper smelting slag was removed to obtain primary metallic vanadium.

[0048] A primary metal vanadium block with a size of 2 cm was placed between a graphite sleeve and a graphite crucible. A molybdenum rod was used as the cathode. A molten salt NaCl-KCl-VCl2 with a vanadium mass fraction of 10% was added. The molar ratio of NaCl to KCl was 1:1. In the protective gas Ar atmosphere, the cathode current density was controlled at 0.25 A / cm 2 , metallic vanadium is obtained after molten salt electrolytic refining.

[0049] After the above operation, the primary metal vanadium composition includes: V: 95.32%, Al: 0.811%, O: 0.92%, N: 0.077%, C: 0.016%, Fe: 0.023%, Si: 0.026%, Cr: 0.024%. The refined metal vanadium composition includes: V: 99.3%, Al: 0.62%, O: 0.048%, N: 0.017%, C: 0.015%, Fe: 0.018%, Si: 0.014%, Cr: 0.019%.

[0050] Comparative Example 2 With the goal of preparing metallic vanadium, 10 kg of vanadium pentoxide with a particle size of 0.05-0.1 mm, 5.2 kg of metallic aluminum with a particle size of 0.5 mm, and 0.6 kg of smelting slag with a particle size of 180 meshes were mixed evenly, put into a graphite crucible reaction vessel, and ignited by magnesium powder with a particle size of 200 meshes to cause a metal thermal reduction reaction. After the reaction was completed and the product was cooled, the upper smelting slag was removed to obtain primary metallic vanadium.

[0051] A primary metal vanadium block with a size of 2 cm was placed in a graphite crucible, a molybdenum rod was used as the cathode, and molten salt NaCl-KCl-VCl2 with a vanadium mass fraction of 8% was added. The molar ratio of NaCl to KCl was 1:1. In the protective gas Ar atmosphere, the cathode current density was controlled at 0.25 A / cm 2 , metallic vanadium is obtained after molten salt electrolytic refining.

[0052] After the above operation, the primary metal vanadium composition includes: V: 92.74%, Al: 0.937%, O: 0.42%, N: 0.071%, C: 0.025%, Fe: 0.031%, Si: 0.029%, Cr: 0.027%. The refined metal vanadium composition includes: V: 99.1%, Al: 0.81%, O: 0.039%, N: 0.016%, C: 0.022%, Fe: 0.016%, Si: 0.017%, Cr: 0.014%.

[0053] Table 1 below shows the components of the products of Examples 1-3 and Comparative Examples 1-2 at different stages.

[0054] Table 1 Composition of products at each stage (%)

[0055] As can be seen from the table above, compared with the comparative example, the Al content in the primary metallic vanadium and the refined metallic vanadium in the solution of the present application is reduced, which indicates that the method can inhibit the formation of the vanadium-aluminum solid solution phase, and the Al phase in the form of oxide in the primary metallic vanadium can be effectively removed by molten salt electrolytic refining. This is also the main reason why the Al content in the refined metallic vanadium of Examples 1-3 is significantly lower than that in the refined metallic vanadium of Comparative Example 1-2.

[0056] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for preparing metallic vanadium by thermite-assisted molten salt electrolysis, characterized in that: The steps include: Step S1: uniformly mixing the vanadium-containing raw material, metallic aluminum, and additives in a weight ratio of 100:25-35:4-8, igniting for aluminothermic reduction reaction, and after the reaction is completed and the product is cooled, removing the upper smelting slag to obtain primary metallic vanadium; Step S2: subjecting the primary metallic vanadium to molten salt electrolytic refining in a protective gas atmosphere to obtain refined metallic vanadium.

2. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 1, characterized in that: The electrolytic cathode used in the molten salt electrolytic refining is selected from at least one of a molybdenum rod, a titanium rod, and a vanadium rod, and the electrolytic anode uses the primary metal vanadium.

3. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 2, characterized in that: The molten salt electrolytic refining uses a graphite crucible as an electrolytic cell. A graphite sleeve with holes is arranged in the graphite crucible. The opening rate of the graphite sleeve is 10% to 60%. The primary metal vanadium is placed between the graphite sleeve and the graphite crucible.

4. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 3, characterized in that: The distance between the cathode and the graphite sleeve is 1-5 cm, and the cathode is horizontally aligned with the anode.

5. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 3, characterized in that: The protective gas is selected from argon and / or helium.

6. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 3, characterized in that: The cathode current density during molten salt electrolytic refining is controlled to be 0.01A / cm 2 ~0.4A / cm 2 .

7. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 1, characterized in that: The molten salt system of molten salt electrolysis refining adopts NaCl-KCl-VCl X , where the molar ratio of NaCl to KCl is 1:1, VCl X The main component is VCl2.

8. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 1, characterized in that: The vanadium-containing raw material is powdered vanadium pentoxide with a particle size of 0.05-1 mm. In terms of mass percentage, V2O5≥99.95%, Fe≤0.01%, Si≤0.01%, and Cr≤0.01%.

9. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 1, characterized in that: The particle size of the metal aluminum is 0.2-0.4 mm, and in terms of mass percentage, Al≥99.95%, Fe≤0.01%, Si≤0.01%, and Cr≤0.01%.

10. The method for preparing metallic vanadium by aluminum thermite coordinated molten salt electrolysis according to claim 1, characterized in that: The additive is mainly composed of aluminum oxide, and the particle size is 60-240 meshes.

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