Preparation and purification method of high-purity sponge vanadium

Abstract

The invention relates to the technical field of chemical metallurgy, and discloses a preparation and purification method of high-purity sponge vanadium, which comprises the following steps: preparing a vertical vacuum reduction furnace, adding a reducing agent, discharging air in the furnace, and introducing shielding gas; heating, adding vanadium chloride for smelting, taking out, putting into a distillation furnace, and carrying out heating and heat preservation treatment; and finally, putting the product into a crucible in an electron beam furnace, vacuumizing, heating and smelting, introducing protective gas into the electron beam furnace after smelting, and cooling to room temperature to obtain a sponge vanadium product. The high-purity sponge vanadium is prepared by adopting a novel vanadium chloride metal thermal reduction-distillation method, and the sponge vanadium is further purified through vacuum electron beam refining, so that the common technical problems of long flow, low product purity and the like of a traditional method for preparing the high-purity metal vanadium are solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical metallurgy, and in particular to a method for preparing and purifying high-purity sponge vanadium. Background Art

[0002] Vanadium is an important type of rare metal, widely used in steel metallurgy, chemical industry, energy storage, high-end alloys, national defense and military industries. About 90% of vanadium is mainly used in the steel industry in the form of ferrovanadium and vanadium-nitrogen alloys, and the remaining 10% of vanadium is used in non-steel fields such as chemical industry, energy storage, and alloys. With the gradual optimization and adjustment of the vanadium industry structure, vanadium is used more and more widely in non-steel fields, especially in the field of high-end vanadium alloys, and the amount of vanadium has shown a surge. High-purity metallic vanadium is a key raw material for the preparation of high-end vanadium alloys, and its purity and key impurities (such as Si, Fe, N, O) play a decisive role in the application performance of subsequent materials. Therefore, the development of preparation technology for high-purity metallic vanadium is of great strategic and practical significance for the upgrading of the vanadium industry structure and high-quality development.

[0003] The preparation technology of high-purity vanadium metal can be generally summarized into the following five methods: (1) vanadium oxide metal thermal reduction method; (2) vanadium oxide metal thermal reduction-electron beam refining to prepare vanadium metal; (3) molten salt electrolysis to prepare vanadium metal; (4) crude vanadium metal chlorination-vanadium chloride gas reduction to prepare vanadium metal powder; (5) iodination and decomposition of vanadium to prepare high-purity vanadium metal. However, the existing preparation methods cannot have advantages in terms of product purity, preparation process, preparation efficiency and application feasibility. Therefore, it is urgent to develop a high-purity vanadium metal preparation method with high product purity, short preparation process, relatively high preparation efficiency and engineering application feasibility.

[0004] Therefore, there is a need in the prior art for improving the preparation and purification methods of high-purity sponge vanadium. Summary of the invention

[0005] In view of this, the purpose of the embodiments of the present invention is to propose a method for preparing and purifying high-purity sponge vanadium, adopt a new method of vanadium chloride metal thermal reduction-distillation to prepare high-purity sponge vanadium, and further purify the sponge vanadium by vacuum electron beam refining, so as to solve the common technical problems faced by traditional methods for preparing high-purity metallic vanadium, such as long process and low product purity.

[0006] Based on the above purpose, the embodiment of the present invention provides a method for preparing and purifying high-purity sponge vanadium, comprising: a. Prepare a vertical vacuum reduction furnace, add the reducing agent to the crucible at the bottom of the furnace, exhaust the air in the furnace and introduce protective gas; b. The reduction furnace is heated to a maximum temperature, and vanadium chloride is gradually added to the bottom crucible. After the addition is completed, the temperature is kept warm, and a protective gas is continuously introduced. After the temperature is kept warm, the furnace is cooled to room temperature; c. Take out the crucible and place it in the distillation furnace, cover the sealing ring of the distillation furnace to evacuate, open the air inlet valve and air outlet valve of the distillation furnace, and introduce protective gas into the distillation furnace; d. Stop introducing protective gas into the distillation furnace, turn on the vacuum pump to evacuate the gas, and set the heating and insulation procedures of the distillation furnace; e. After the insulation is completed, the vacuum pump stops pumping, the protective gas is introduced into the furnace again, and the materials in the distillation furnace are cooled to room temperature, and the product in the crucible is taken out; f. Place the product in a crucible in an electron beam furnace, evacuate the crucible, heat up and melt it, introduce protective gas into the electron beam furnace after melting, and after cooling to room temperature, obtain a sponge vanadium product.

[0007] In some embodiments, in step a, the vertical reduction furnace is divided into a bottom reaction zone and a top feeding zone, the bottom reaction zone is heated by a resistance wire, and the top feeding zone is cooled by circulating cooling water.

[0008] In some embodiments, in step a, when exhausting, the sealing ring of the vertical vacuum reduction furnace is tightly covered, the air intake and exhaust pipelines are connected, the air intake valve of the vertical vacuum reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust until the vacuum degree is within 100Pa.

[0009] In some embodiments, in step a, the reducing agent is any one of metal magnesium, metal aluminum, and metal calcium, the crucible is any one of a corundum crucible and a graphite crucible, and the protective gas is any one of argon and helium.

[0010] In some embodiments, in step b, the maximum temperature of the vertical vacuum reduction furnace is 750-950° C., and the amount of vanadium chloride added is controlled according to 1 / 2-2 / 3 of the theoretical amount of vanadium chloride required for the reaction of vanadium chloride and magnesium to generate metallic vanadium.

[0011] In some embodiments, the purity of vanadium chloride is above 99.9%, and vanadium chloride includes vanadium tetrachloride, vanadium trichloride and vanadium dichloride.

[0012] In some embodiments, in step b, the furnace temperature is controlled not to exceed 150° C. during the feeding process, and the temperature is kept for 30 to 240 minutes after the feeding is completed.

[0013] In some embodiments, in step c, a vacuum pump is used to evacuate the distillation furnace until the vacuum degree in the distillation furnace reaches less than 50 Pa before the next step of heating. The vacuum degree in the distillation furnace during the heating and insulation process is (1×10 -2 )~5Pa.

[0014] In some embodiments, in step d, the heating rate is 5-15° C. / min, the maximum temperature is 900-1200° C., and the holding time is 30-600 min.

[0015] In some embodiments, in step f, the vacuum degree of the electron beam furnace is 1×(10 -3 ~10 -2 )Pa, the temperature is 2000~3000℃.

[0016] The present invention has at least the following beneficial technical effects: The present invention adopts a new method of chloride metal thermal reduction-distillation to prepare a high-purity sponge vanadium product with a product purity of more than 99.9%. Further, through electron beam refining, a metal vanadium product with a purity of 99.95%-99.99% is prepared. Compared with the traditional method of preparing crude metal vanadium by metal thermal reduction of vanadium oxide-multi-stage refining of crude metal vanadium, this method has the advantages of short process, mild process conditions and high product purity. At the same time, the magnesium chloride by-product can be converted into metal magnesium and chlorine by electrolysis, thereby realizing the circulation of magnesium and chlorine (magnesium is circulated to the reduction stage, and chlorine is used to prepare upstream vanadium chloride raw materials), which is conducive to the low-cost preparation of high-purity metal vanadium and better application feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 This is a schematic diagram of an embodiment of the method for preparing and purifying high-purity sponge vanadium provided by the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0021] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] like Figure 1 The preparation and purification method of high-purity sponge vanadium provided by the present invention comprises the following steps: a. Prepare a vertical vacuum reduction furnace, add the reducing agent to the crucible at the bottom of the furnace, exhaust the air in the furnace and introduce protective gas; b. The reduction furnace is heated to a maximum temperature, and vanadium chloride is gradually added to the bottom crucible. After the addition is completed, the temperature is kept warm, and a protective gas is continuously introduced. After the temperature is kept warm, the furnace is cooled to room temperature; c. Take out the crucible and place it in the distillation furnace, cover the sealing ring of the distillation furnace to evacuate, open the air inlet valve and air outlet valve of the distillation furnace, and introduce protective gas into the distillation furnace; d. Stop introducing protective gas into the distillation furnace, turn on the vacuum pump to evacuate the gas, and set the heating and insulation procedures of the distillation furnace; e. After the insulation is completed, the vacuum pump stops pumping, the protective gas is introduced into the furnace again, and the materials in the distillation furnace are cooled to room temperature, and the product in the crucible is taken out; f. Place the product in a crucible in an electron beam furnace, evacuate the crucible, heat up and melt it, introduce protective gas into the electron beam furnace after melting, and after cooling to room temperature, obtain a sponge vanadium product.

[0023] Furthermore, in step a, the vertical reduction furnace is divided into a bottom reaction zone and a top charging zone, the bottom reaction zone is heated by a resistance wire, and the top charging zone is cooled by circulating cooling water.

[0024] Furthermore, in step a, when exhausting, the sealing ring of the vertical vacuum reduction furnace is tightly covered, the air intake and exhaust pipelines are connected, the air intake valve of the vertical vacuum reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust until the vacuum degree is within 100Pa.

[0025] Furthermore, in step a, the reducing agent is any one of metal magnesium, metal aluminum, and metal calcium, preferably metal magnesium, the diameter of the magnesium block is 5-10 mm, and the purity (mass fraction) is ≥ 99.9%. The crucible is any one of a corundum crucible and a graphite crucible, the crucible material must be resistant to high temperature and chloride corrosion, and the protective gas is any one of argon and helium.

[0026] Furthermore, in step b, the maximum temperature of the vertical vacuum reduction furnace is 750-950° C., and the amount of vanadium chloride added is controlled according to 1 / 2-2 / 3 of the theoretical amount of vanadium chloride required for the reaction of vanadium chloride and magnesium to generate metallic vanadium.

[0027] Furthermore, the purity of vanadium chloride is above 99.9%. Vanadium chloride includes vanadium tetrachloride, vanadium trichloride and vanadium dichloride. Vanadium tetrachloride is in liquid state, while vanadium trichloride and vanadium dichloride are in solid powder state.

[0028] Furthermore, in step b, the furnace temperature is controlled not to exceed 150° C. during the feeding process, and the temperature is kept at 30 to 240 minutes after the feeding is completed.

[0029] Furthermore, in step c, a vacuum pump is used to evacuate air until the vacuum degree in the distillation furnace reaches less than 50 Pa.

[0030] Furthermore, in step d, the heating rate is 5-15°C / min, the maximum temperature is 900-1200°C, and the holding time is 30-600min.

[0031] Furthermore, in step f, the vacuum degree of the electron beam furnace is 1×(10 -3 ~10 -2 )Pa, the temperature is 2000~3000℃.

[0032] The preferred embodiment of the present invention is as follows: in a vertical vacuum reduction furnace in which a resistance wire is used for heating in the bottom reaction zone and circulating cooling water is used for cooling in the top feeding zone, a magnesium block with a diameter of 5-10 mm and a purity (mass fraction) ≥ 99.9% is added to a corundum crucible at the bottom, the sealing ring of the vertical vacuum reduction furnace is tightly covered, the air inlet and exhaust pipelines are connected, the air inlet valve of the vertical vacuum reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust until the vacuum degree in the reduction furnace is within 100 Pa; the vertical vacuum reduction furnace is turned on. The air inlet valve of the furnace is used to introduce argon gas with a purity (volume fraction) of more than 99.9% as protective gas into the furnace; the vertical vacuum reduction furnace is heated to 750-950℃. When it reaches the highest temperature, vanadium tetrachloride, vanadium trichloride or vanadium dichloride with a purity (mass fraction) of more than 99.9% are gradually added to the crucible at the bottom of the vertical vacuum reduction furnace. The amount of vanadium chloride raw material added is controlled according to 1 / 2-2 / 3 of the theoretical value. During the feeding process, the feeding rate is controlled according to the furnace temperature rise value not exceeding 150℃. After the feeding is completed, Keep the temperature at 750-950℃ for 30-240min. During the feeding and keeping temperature preservation process, keep the argon gas with a purity (volume fraction) of more than 99.9% as the protective gas into the furnace. After the keeping temperature is over, cool the materials in the crucible of the vertical vacuum reduction furnace to room temperature with the furnace. During the cooling process, keep the argon gas with a purity (volume fraction) of more than 99.9% as the protective gas into the furnace. After the temperature in the reduction furnace drops to room temperature, quickly take out the crucible in the vertical vacuum reduction furnace, and place the crucible and the materials in the crucible in a distillation furnace. In the furnace, cover the sealing ring of the distillation furnace, open the inlet valve and outlet valve of the distillation furnace, and introduce argon with a purity (volume fraction) of more than 99.9% into the distillation furnace for more than 30 minutes; after the ventilation is completed, turn on the vacuum pump of the distillation furnace to evacuate until the vacuum degree in the distillation furnace reaches less than 50Pa and start the next step of heating; adjust the heating rate of the distillation furnace to 5-15℃ / min, the maximum temperature to 900-1200℃, the insulation time to 0.5-10h, and the vacuum degree in the distillation furnace during the heating and insulation process is (1×10 -2 )~5Pa; after keeping warm, the temperature starts to drop naturally, the vacuum pump stops pumping, and argon with a purity (volume fraction) of more than 99.9% is introduced into the furnace as a protective gas, and the materials in the distillation furnace are cooled to room temperature, and finally the product in the crucible is taken out. The prepared sponge vanadium is placed in an electron beam furnace and heated at 1×10 -3 ~1×10 -2 Pa vacuum degree, refining is carried out in the temperature range of 2000-3000℃. After the refining is completed, argon gas with a purity of more than 99.9% is introduced into the furnace as a protective gas. After the furnace is cooled, the product is taken out.

[0033] The present invention will be further explained below in conjunction with specific embodiments.

[0034] Embodiment 1: In a vertical vacuum reduction furnace with a resistance wire for heating in the bottom reaction zone and circulating cooling water for cooling in the top feeding zone, 3980g of magnesium blocks with a diameter of 5-10mm and a purity of 99.95wt.% are added to the corundum crucible at the bottom of the empty reduction furnace, the sealing ring of the reduction furnace is tightly covered, the air inlet and exhaust pipelines are connected, the air inlet valve of the reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust. When the vacuum degree in the reduction furnace is 80Pa, the vacuum pump is turned off; the air inlet valve of the reduction furnace is opened, and argon with a purity (volume fraction) of 99.99% is introduced into the furnace as a protective gas; the reduction furnace is heated to 750℃ and kept warm, and the bottom of the reduction furnace is pumped with a peristaltic pump. 8000g of vanadium tetrachloride with a purity (mass fraction) of 99.9% was gradually added to the crucible. During the feeding process, the furnace temperature fluctuated between 750-900℃. After the feeding was completed, the furnace was kept warm at a set temperature of 750℃ for 30min. During the feeding and keeping warm process, argon with a purity (volume fraction) of 99.99% was continuously introduced into the furnace as a protective gas. After the keeping warm process, the furnace was cooled naturally to allow the materials in the crucible of the reduction furnace to cool to room temperature along with the furnace. During the cooling process, argon with a purity (volume fraction) of 99.99% was continuously introduced into the furnace as a protective gas. After the temperature in the reduction furnace dropped to room temperature, the crucible was quickly taken out and placed in a distillation furnace. The cover was tightly closed. The distillation furnace sealing ring is opened, the air inlet valve and the air outlet valve of the distillation furnace are opened, and argon gas with a purity (volume fraction) of 99.99% is introduced into the distillation furnace for 60 minutes; after the ventilation is completed, the vacuum pump of the distillation furnace is turned on to evacuate until the vacuum degree in the distillation furnace reaches 20Pa; then, at a heating rate of 5℃ / min, the temperature of the distillation furnace is increased to 900℃, and kept at this temperature for 600 minutes. The vacuum degree in the distillation furnace is maintained at 5Pa during the heating and insulation process; after the insulation is completed, the vacuum pump stops evacuating, and the distillation furnace is cooled naturally. During the cooling process, argon gas with a purity (volume fraction) of 99.99% is introduced into the furnace as a protective gas, and the materials in the distillation furnace are cooled. After cooling to room temperature, the vanadium sponge product in the crucible was taken out, a total of 1744g, the purity (mass fraction) of the vanadium sponge was 99.900%, the impurity O content (mass fraction) was 0.058%, the N content (mass fraction) was 0.005%, the C content (mass fraction) was 0.007%, the Al content (mass fraction) was 0.002%, the Cl content (mass fraction) was 0.010%, the Si content (mass fraction) was 0.002%, the Fe content (mass fraction) was 0.004%, and the Cr content (mass fraction) was 0.012%; 1000g of vanadium sponge was placed in an electron beam furnace, and the vacuum degree in the furnace was controlled at 1×10 -2Pa, refined at 2000℃. After the refining, argon with a purity (volume fraction) of 99.99% was introduced into the furnace as a protective gas for cooling. After the temperature in the furnace dropped to room temperature, 780g of metallic vanadium sample was obtained. The vanadium content (mass fraction) of the product was 99.950%, and the impurities included O content (mass fraction) 0.030%, N content (mass fraction) 0.004%, C content (mass fraction) 0.006%, Al content (mass fraction) 0.001%, Cl content (mass fraction) 0.001%, Si content (mass fraction) 0.001%, Fe content (mass fraction) 0.002%, and Cr content (mass fraction) 0.002%.

[0035] Embodiment 2: In a vertical vacuum reduction furnace with a resistance wire heating in the bottom reaction zone and circulating cooling water cooling in the top feeding zone, 2104g of magnesium blocks with a diameter of 5-10mm and a purity of 99.95wt.% are added to the corundum crucible at the bottom of the empty reduction furnace, the sealing ring of the reduction furnace is tightly covered, the air inlet and exhaust pipelines are connected, the air inlet valve of the reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust. When the vacuum degree in the reduction furnace is 50Pa, the vacuum pump is turned off; the air inlet valve of the reduction furnace is opened, and argon gas with a purity (volume fraction) of 99.99% is introduced into the furnace as a protective gas; the reduction furnace is heated to 850℃ and kept warm, and a total of 9200g of vanadium trichloride with a purity (mass fraction) of 99.95% is gradually added to the crucible at the bottom of the reduction furnace through the feeding device. During the feeding process, the furnace temperature fluctuates between 850-980℃. After the feeding is completed, it is kept warm for 120mi at the set temperature of 850℃ n, during the process of adding materials and keeping warm, argon with a purity (volume fraction) of 99.99% is continuously introduced into the furnace as a protective gas; after the end of the insulation, the temperature is naturally cooled down to allow the materials in the crucible of the reduction furnace to cool to room temperature with the furnace, and during the cooling process, argon with a purity (volume fraction) of 99.99% is continuously introduced into the furnace as a protective gas; after the temperature in the reduction furnace drops to room temperature, the crucible is quickly taken out and placed in the distillation furnace, the sealing ring of the distillation furnace is tightly covered, the air inlet valve and the air outlet valve of the distillation furnace are opened, and argon with a purity (volume fraction) of 99.99% is introduced into the distillation furnace for 60 minutes; after the ventilation is completed, the vacuum pump of the distillation furnace is turned on to evacuate until the vacuum degree in the distillation furnace reaches 50Pa; then, at a heating rate of 10℃ / min, the temperature of the distillation furnace is raised to 1100℃, and kept at this temperature for 240 minutes. During the heating and insulation process, the vacuum degree in the distillation furnace is maintained at 1×10 -2Pa; after the insulation is completed, the vacuum pump stops pumping, and the distillation furnace cools down naturally. During the cooling process, argon with a purity (volume fraction) of 99.99% is introduced into the furnace as a protective gas. After the materials in the distillation furnace are cooled to room temperature, the sponge vanadium product in the crucible is taken out, a total of 2684g, the purity (mass fraction) of the sponge vanadium is 99.926%, the impurity O content (mass fraction) is 0.041%, the N content (mass fraction) is 0.004%, the C content (mass fraction) is 0.006%, the Al content (mass fraction) is 0.003%, the Cl content (mass fraction) is 0.008%, the Si content (mass fraction) is 0.001%, the Fe content (mass fraction) is 0.003%, and the Cr content (mass fraction) is 0.008%; 2000g of sponge vanadium is placed in an electron beam furnace, and the vacuum degree in the furnace is controlled at 1×10 -3 Pa, refined at 3000℃. After the refining, argon with a purity (volume fraction) of 99.99% was introduced into the furnace as a protective gas for cooling. After the temperature in the furnace dropped to room temperature, 1200g of metallic vanadium sample was obtained. The vanadium content (mass fraction) of the product was 99.990%, and the impurities O content (mass fraction) was 0.003%, N content (mass fraction) was 0.002%, C content (mass fraction) was 0.002%, Al was not detected (below the detection limit), Cl was not detected (below the detection limit), Si content (mass fraction) was 0.001%, Fe content (mass fraction) was 0.001%, and Cr content (mass fraction) was 0.001%.

[0036] Embodiment 3: In a vertical vacuum reduction furnace with a resistance wire for heating in the bottom reaction zone and circulating cooling water for cooling in the top feeding zone, 2976g of magnesium blocks with a diameter of 5-10mm and a purity of 99.95wt.% are added to the corundum crucible at the bottom of the empty reduction furnace, the sealing ring of the reduction furnace is tightly covered, the air inlet and exhaust pipelines are connected, the air inlet valve of the reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust. When the vacuum degree in the reduction furnace is 100Pa, the vacuum pump is turned off; the air inlet valve of the reduction furnace is opened, and argon with a purity (volume fraction) of 99.99% is introduced into the furnace as a protective gas; the reduction furnace is heated to 950℃ and kept warm, and the bottom of the reduction furnace is fed with a feeding device. A total of 8400g of vanadium dichloride with a purity (mass fraction) of 99.95% was gradually added to the crucible. During the feeding process, the furnace temperature fluctuated between 950-1060°C. After the feeding was completed, the furnace was kept warm at a set temperature of 950°C for 240 minutes. During the feeding and keeping warm process, argon with a purity (volume fraction) of 99.99% was continuously introduced into the furnace as a protective gas. After the keeping warm process, the furnace was cooled naturally to allow the materials in the crucible of the reduction furnace to cool to room temperature along with the furnace. During the cooling process, argon with a purity (volume fraction) of 99.99% was continuously introduced into the furnace as a protective gas. After the temperature in the reduction furnace dropped to room temperature, the crucible was quickly taken out and placed in a distillation furnace, and the cover was tightly closed. Remove the sealing ring of the distillation furnace, open the air inlet valve and the air outlet valve of the distillation furnace, and introduce argon with a purity (volume fraction) of 99.99% into the distillation furnace for 60 minutes; after the ventilation is completed, turn on the vacuum pump of the distillation furnace to evacuate until the vacuum degree in the distillation furnace reaches 10Pa; then, at a heating rate of 15℃ / min, raise the temperature of the distillation furnace to 1200℃, and keep it at this temperature for 30 minutes. During the heating and insulation process, the vacuum degree in the distillation furnace is maintained at 0.1Pa; after the insulation is completed, the vacuum pump stops evacuating, and the distillation furnace cools down naturally. During the cooling process, introduce argon with a purity (volume fraction) of 99.99% as a protective gas into the furnace, and wait for the distillation furnace to cool down. After the material was cooled to room temperature, the sponge vanadium product in the crucible was taken out, totaling 3192 g, with a sponge vanadium purity (mass fraction) of 99.919%, impurity O content (mass fraction) of 0.048%, N content (mass fraction) of 0.005%, C content (mass fraction) of 0.007%, Al content (mass fraction) of 0.001%, Cl content (mass fraction) of 0.006%, Si content (mass fraction) of 0.002%, Fe content (mass fraction) of 0.005%, Cr content (mass fraction) of 0.007%; 2500 g of sponge vanadium was placed in an electron beam furnace, and the vacuum degree in the furnace was controlled at 5×10 -3Pa, refined at 2500℃. After the refining, argon with a purity (volume fraction) of 99.99% was introduced into the furnace as a protective gas for cooling. After the temperature in the furnace dropped to room temperature, 1775g of metallic vanadium sample was obtained. The vanadium content (mass fraction) of the product was 99.978%, and the impurities O content (mass fraction) was 0.008%, N content (mass fraction) was 0.002%, C content (mass fraction) was 0.004%, Al was not detected (below the detection limit), Cl was not detected (below the detection limit), Si content (mass fraction) was 0.001%, Fe content (mass fraction) was 0.003%, and Cr content (mass fraction) was 0.002%.

[0037] The present invention adopts a new method of chloride metal thermal reduction-distillation to prepare a high-purity sponge vanadium product, and the product purity (mass fraction) can reach more than 99.9%. Further through electron beam refining, a metal vanadium product with a purity of 99.95%-99.99% is prepared. Compared with the traditional method of preparing crude metal vanadium by metal thermal reduction of vanadium oxide-multi-stage refining of crude metal vanadium, this method has the advantages of short process, mild process conditions, and high product purity. At the same time, the magnesium chloride by-product can be converted into metallic magnesium and chlorine by electrolysis, thereby realizing the circulation of magnesium and chlorine (magnesium is circulated to the reduction stage, and chlorine is used to prepare upstream vanadium chloride raw materials), which is conducive to the low-cost preparation of high-purity metal vanadium and better application feasibility.

[0038] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0039] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0040] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0041] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for preparing and purifying high-purity sponge vanadium, characterized in that: include: a. Prepare a vertical vacuum reduction furnace, add the reducing agent to the crucible at the bottom of the furnace, exhaust the air in the furnace and introduce protective gas; b. The reduction furnace is heated to a maximum temperature, and vanadium chloride is gradually added to the bottom crucible. After the addition is completed, the temperature is kept warm, and a protective gas is continuously introduced. After the temperature is kept warm, the furnace is cooled to room temperature; c. Take out the crucible and place it in the distillation furnace, cover the sealing ring of the distillation furnace to evacuate, open the air inlet valve and air outlet valve of the distillation furnace, and introduce protective gas into the distillation furnace; d. Stop introducing protective gas into the distillation furnace, turn on the vacuum pump to evacuate the gas, and set the heating and insulation procedures of the distillation furnace; e. After the insulation is completed, the vacuum pump stops pumping, the protective gas is introduced into the furnace again, and the materials in the distillation furnace are cooled to room temperature, and the product in the crucible is taken out; f. The product is placed in an electron beam furnace, the crucible is evacuated, the temperature is increased for melting, and after melting, a protective gas is introduced into the electron beam furnace, and after cooling to room temperature, a sponge vanadium product is obtained.

2. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step a, the vertical reduction furnace is divided into a bottom reaction zone and a top feeding zone. The bottom reaction zone is heated by a resistance wire, and the top feeding zone is cooled by circulating cooling water.

3. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step a, when exhausting, the sealing ring of the vertical vacuum reduction furnace is tightly covered, the air intake and exhaust pipelines are connected, the air intake valve of the vertical vacuum reduction furnace is closed, the air outlet valve is opened, and the vacuum pump is turned on to exhaust until the vacuum degree is within 100Pa.

4. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step a, the reducing agent is any one of metal magnesium, metal aluminum, and metal calcium, the crucible is any one of a corundum crucible and a graphite crucible, and the protective gas is any one of argon and helium.

5. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step b, the maximum temperature of the vertical vacuum reduction furnace is 750-950° C., and the amount of vanadium chloride added is controlled according to 1 / 2-2 / 3 of the theoretical amount of vanadium chloride required for the reaction of vanadium chloride and magnesium to generate metallic vanadium.

6. The method for preparing and purifying high-purity sponge vanadium according to claim 5, characterized in that: The purity of the vanadium chloride is above 99.9%, and the vanadium chloride includes vanadium tetrachloride, vanadium trichloride and vanadium dichloride.

7. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step b, the furnace temperature is controlled not to exceed 150° C. during the feeding process, and the temperature is kept at 30 to 240 minutes after the feeding is completed.

8. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step c, a vacuum pump is used to evacuate the air until the vacuum degree in the distillation furnace reaches less than 50 Pa and then the next step of heating is started. The vacuum degree in the distillation furnace during the heating and insulation process is (1×10 -2 )~5Pa.

9. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step d, the heating rate is 5-15°C / min, the maximum temperature is 900-1200°C, and the holding time is 30-600min.

10. The method for preparing and purifying high-purity sponge vanadium according to claim 1, characterized in that: In step f, the vacuum degree of the electron beam furnace is 1× (10 -3 ~10 -2 )Pa, the temperature is 2000~3000℃.

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