Method for preparing and purifying high-purity vanadium sponge

Abstract

The present invention relates to the technical field of chemical metallurgy, and provides a method for preparing and purifying high-purity vanadium sponge. The method comprises: preparing a vertical vacuum reduction furnace, adding a reducing agent thereto, removing air from the furnace and introducing a protective gas thereinto; performing heating, adding vanadium chloride, then performing smelting, and after removal, placing same into a distillation furnace for heating and temperature-holding treatments; and finally, placing a product into a crucible in an electron beam furnace, performing evacuation, heating same to perform smelting, introducing a protective gas into the electron beam furnace after smelting, and cooling same to room temperature, so as to obtain a vanadium sponge product. In the present invention, high-purity vanadium sponge is prepared from a chloride of vanadium by means of a new metallothermic reduction-distillation method, and is further purified by means of vacuum electron beam refining. Therefore, the common technical problems of a long process, a low product purity, etc., during the preparation of high-purity vanadium metal by means of traditional methods are solved.

Description

A method for preparing and purifying high-purity sponge vanadium

[0001] This application claims priority to Chinese Patent Application No. 202411930573.4, filed on December 25, 2024, entitled "A Method for the Preparation and Purification of High-Purity Sponge Vanadium", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of chemical metallurgy technology, and in particular to a method for preparing and purifying high-purity sponge vanadium. Background Technology

[0003] Vanadium is an important rare metal widely used in steel metallurgy, chemicals, energy storage, high-end alloys, and defense industries. Approximately 90% of vanadium is used in the steel industry in the form of ferrovanadium and vanadium-nitrogen alloys, while the remaining 10% is used in non-steel fields such as chemicals, energy storage, and alloys. With the gradual optimization and adjustment of the vanadium industry structure, the application of vanadium in non-steel fields is becoming increasingly widespread, especially in the field of high-end vanadium alloys, where vanadium consumption is showing 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, and O) play a decisive role in the performance of subsequent materials. Therefore, developing high-purity metallic vanadium preparation technology is of significant strategic and practical importance for the upgrading and high-quality development of the vanadium industry structure.

[0004] The preparation techniques for high-purity metallic vanadium can be broadly categorized into five methods: (1) metallothermic reduction of vanadium oxides; (2) metallothermic reduction of vanadium oxides followed by electron beam refining to prepare metallic vanadium; (3) molten salt electrolysis to prepare metallic vanadium; (4) chlorination of crude metallic vanadium followed by gas reduction of vanadium chloride to prepare metallic vanadium powder; and (5) iodination and decomposition of vanadium to prepare high-purity metallic vanadium. However, existing preparation methods do not simultaneously offer advantages in terms of product purity, preparation process, preparation efficiency, and application feasibility. Therefore, there is an urgent need to develop a high-purity metallic vanadium preparation method that offers high product purity, a short preparation process, high preparation efficiency, and relatively high feasibility for engineering applications.

[0005] Therefore, there is a need to improve the existing methods for preparing and purifying high-purity sponge vanadium. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a method for preparing and purifying high-purity sponge vanadium. The method uses a novel metal thermal reduction-distillation method of vanadium chloride to prepare high-purity sponge vanadium, and further purifies the sponge vanadium by vacuum electron beam refining, thus solving the common technical problems of long process and low product purity faced by traditional methods for preparing high-purity metallic vanadium.

[0007] To achieve the above objectives, embodiments of the present invention provide a method for preparing and purifying high-purity sponge vanadium, comprising:

[0008] a. Prepare a vertical vacuum reduction furnace, add the reducing agent to the crucible at the bottom of the furnace, purge the air from the furnace, and then introduce protective gas;

[0009] b. Heat the reduction furnace to the maximum temperature, then gradually add vanadium chloride to the bottom crucible. After the addition is complete, keep the furnace at the maximum temperature and continuously introduce protective gas. After the furnace is kept at the maximum temperature, cool it down to room temperature.

[0010] c. Remove the crucible and place it in the distillation furnace. Tighten the sealing ring of the distillation furnace and evacuate it. Open the gas inlet valve and gas outlet valve of the distillation furnace and introduce protective gas into the distillation furnace.

[0011] d. Stop supplying protective gas into the distillation furnace, turn on the vacuum pump to evacuate the gas, and set the heating and holding programs for the distillation furnace;

[0012] e. After the heat preservation is completed, the vacuum pump stops pumping air, the protective gas is introduced into the furnace again, and the material in the distillation furnace is cooled to room temperature. The product in the crucible is then removed.

[0013] f. Place the product in a crucible inside an electron beam furnace, evacuate, heat and melt. After melting, introduce protective gas into the electron beam furnace. After cooling to room temperature, obtain the sponge vanadium product.

[0014] 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 resistance wire, and the top feeding zone is cooled by circulating cooling water.

[0015] In some embodiments, during step a, the sealing ring of the vertical vacuum reduction furnace is tightened, the air inlet and exhaust pipes 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 the gas to a vacuum level of less than 100 Pa.

[0016] In some embodiments, in step a, the reducing agent is any one of metallic magnesium, metallic aluminum, and metallic calcium; the crucible is any one of corundum crucible and graphite crucible; and the protective gas is any one of argon and helium.

[0017] 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 to 2 / 3 of the theoretical amount of vanadium chloride required for the reaction of vanadium chloride and magnesium to produce metallic vanadium.

[0018] In some embodiments, the purity of vanadium chloride is above 99.9%, and vanadium chloride includes vanadium tetrachloride, vanadium trichloride, and vanadium dichloride.

[0019] In some implementations, in step b, the furnace temperature is controlled to not exceed 150°C during the feeding process, and the furnace is kept warm for 30–240 minutes after the feeding is completed.

[0020] In some embodiments, in step c, a vacuum pump is used to evacuate the gas until the vacuum level inside the distillation furnace reaches below 50 Pa before starting the next heating step. During the heating and holding process, the vacuum level inside the distillation furnace is (1×10⁻⁶ Pa). -2 )~5Pa.

[0021] 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.

[0022] In some embodiments, in step f, the vacuum degree of the electron beam furnace is 1×(10⁻⁶). -3 ~10 -2 Pa, with a temperature of 2000–3000℃.

[0023] The present invention has at least the following beneficial technical effects:

[0024] This invention employs a novel metallothermic reduction-distillation method using chlorides to prepare high-purity sponge vanadium products with a purity exceeding 99.9%. Further electron beam refining yields metallic vanadium products with a purity of 99.95%-99.99%. Compared to traditional methods involving the metallothermic reduction of vanadium oxides to prepare crude metallic vanadium and subsequent multi-stage refining, this method offers advantages such as a shorter process flow, milder process conditions, and higher product purity. Furthermore, by electrolysis, magnesium chloride byproducts can be converted into metallic magnesium and chlorine gas, thus achieving magnesium and chlorine recycling (magnesium is recycled to the reduction stage, and chlorine gas is used to prepare upstream vanadium chloride raw materials). This facilitates the low-cost preparation of high-purity metallic vanadium and enhances its application feasibility. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0026] Figure 1 is a schematic diagram of an embodiment of the preparation and purification method of high-purity sponge vanadium provided by the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0028] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0029] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] Figure 1 illustrates the preparation and purification method for high-purity sponge vanadium provided by this invention, comprising the following steps:

[0031] a. Prepare a vertical vacuum reduction furnace, add the reducing agent to the crucible at the bottom of the furnace, purge the air from the furnace, and then introduce protective gas;

[0032] b. Heat the reduction furnace to the maximum temperature, then gradually add vanadium chloride to the bottom crucible. After the addition is complete, keep the furnace at the maximum temperature and continuously introduce protective gas. After the furnace is kept at the maximum temperature, cool it down to room temperature.

[0033] c. Remove the crucible and place it in the distillation furnace. Tighten the sealing ring of the distillation furnace and evacuate it. Open the gas inlet valve and gas outlet valve of the distillation furnace and introduce protective gas into the distillation furnace.

[0034] d. Stop supplying protective gas into the distillation furnace, turn on the vacuum pump to evacuate the gas, and set the heating and holding programs for the distillation furnace;

[0035] e. After the heat preservation is completed, the vacuum pump stops pumping air, the protective gas is introduced into the furnace again, and the material in the distillation furnace is cooled to room temperature. The product in the crucible is then removed.

[0036] f. Place the product in a crucible inside an electron beam furnace, evacuate, heat and melt. After melting, introduce protective gas into the electron beam furnace. After cooling to room temperature, obtain the sponge vanadium product.

[0037] Furthermore, 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 resistance wire, and the top feeding zone is cooled by circulating cooling water.

[0038] Further, in step a, during exhaust, the sealing ring of the vertical vacuum reduction furnace is tightened, the inlet and exhaust pipes are connected, the inlet valve of the vertical vacuum reduction furnace is closed, the outlet valve is opened, and the vacuum pump is turned on to exhaust to a vacuum level of less than 100 Pa.

[0039] Further, in step a, the reducing agent is any one of metallic magnesium, metallic aluminum, and metallic calcium, preferably metallic magnesium, with a magnesium block diameter of 5-10 mm and a purity (mass fraction) ≥99.9%. The crucible is any one of corundum crucible and graphite crucible, and the crucible material must be resistant to high temperature and chloride corrosion. The protective gas is any one of argon and helium.

[0040] 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 to 2 / 3 of the theoretical amount of vanadium chloride required for the reaction of vanadium chloride and magnesium to produce metallic vanadium.

[0041] 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 form, while vanadium trichloride and vanadium dichloride are solid powders.

[0042] Furthermore, in step b, the furnace temperature is controlled to not exceed 150°C during the feeding process, and the furnace is kept warm for 30–240 minutes after the feeding is completed.

[0043] Furthermore, in step c, a vacuum pump is used to evacuate the gas until the vacuum level inside the distillation furnace reaches less than 50 Pa.

[0044] Furthermore, in step d, the heating rate is 5–15 °C / min, the maximum temperature is 900–1200 °C, and the holding time is 30–600 min.

[0045] Furthermore, in step f, the vacuum degree of the electron beam furnace is 1×(10⁻⁶). -3 ~10 -2 Pa, with a temperature of 2000–3000℃.

[0046] A preferred embodiment of the present invention is as follows: In a vertical vacuum reduction furnace where the bottom reaction zone is heated by resistance wire and the top feeding zone is cooled by circulating cooling water, magnesium blocks with a diameter of 5-10 mm and a purity (mass fraction) ≥99.9% are added to the corundum crucible at the bottom. The sealing ring of the vertical vacuum reduction furnace is tightened, the inlet and outlet pipes are connected, the inlet valve of the vertical vacuum reduction furnace is closed, the outlet valve is opened, and the vacuum pump is turned on to exhaust gas until the vacuum degree inside the reduction furnace is below 100 Pa; the vertical vacuum reduction furnace is then started. The furnace's inlet valve introduces argon gas with a purity (volume fraction) of 99.9% or higher as a protective gas. The vertical vacuum reduction furnace is heated to 750-950℃. When the maximum temperature is reached, vanadium tetrachloride, vanadium trichloride, or vanadium dichloride with a purity (mass fraction) of 99.9% or higher is gradually added to the crucible at the bottom of the furnace. The amount of vanadium chloride added is controlled according to 1 / 2 to 2 / 3 of the theoretical value. During the feeding process, the feeding rate is controlled so that the furnace temperature rise does not exceed 150℃. After feeding is completed, ... Hold the material at a maximum temperature of 750-950℃ for 30-240 minutes, continuously introducing argon gas with a purity (volume fraction) of 99.9% or higher as a protective gas during the feeding and holding process. After the holding period, cool the material in the crucible of the vertical vacuum reduction furnace to room temperature along with the furnace, continuously introducing argon gas with a purity (volume fraction) of 99.9% or higher as a protective gas during the cooling process. Once the temperature inside the reduction furnace has dropped to room temperature, quickly remove the crucible from the vertical vacuum reduction furnace and place the crucible and the material inside it in a distillation chamber. Inside the furnace, tighten the sealing ring, open the inlet and outlet valves, and introduce argon gas with a purity (volume fraction) of 99.9% or higher into the furnace for at least 30 minutes. After the gas introduction is complete, turn on the vacuum pump to evacuate the furnace until the vacuum level reaches below 50 Pa before starting the next heating step. Adjust the heating rate of the furnace to 5-15℃ / min, the maximum temperature to 900-1200℃, and the holding time to 0.5-10 hours. During the heating and holding process, maintain a vacuum level of (1×10⁻⁶ Pa) inside the furnace. -2 ~5Pa; after holding at this temperature, allow it to cool naturally. Stop the vacuum pump and introduce argon gas with a purity (volume fraction) of 99.9% or higher into the furnace as a protective gas. Cool the material in the distillation furnace to room temperature, and finally remove the product from the crucible. Place the prepared sponge vanadium in an electron beam furnace at 1×10 -3 ~1×10 -2 The refining process is carried out under a vacuum of Pa and a temperature range of 2000-3000℃. After refining, argon gas with a purity of 99.9% or higher is introduced into the furnace as a protective gas. After the furnace cools down, the product is taken out.

[0047] The present invention will be further explained below with reference to specific embodiments.

[0048] Example 1:

[0049] In a vertical vacuum reduction furnace with resistance wire heating in the bottom reaction zone and circulating cooling water 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 furnace sealing ring is tightened, the inlet and outlet pipes are connected, the inlet valve of the reduction furnace is closed, the outlet valve is opened, and the vacuum pump is turned on to exhaust gas. When the vacuum degree in the reduction furnace reaches 80Pa, the vacuum pump is turned off. The 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 750℃ and held at that temperature. A peristaltic pump is used to pump gas to the bottom of the reduction furnace. 8000g of vanadium tetrachloride with a purity of 99.9% (mass fraction) was gradually added to the crucible. During the addition process, the furnace temperature fluctuated between 750-900℃. After the addition was completed, the furnace was held at a set temperature of 750℃ for 30 minutes. During the addition and holding process, argon gas with a purity of 99.99% (volume fraction) was continuously introduced into the furnace as a protective gas. After the holding period, the furnace was allowed to cool naturally, allowing the material in the crucible to cool to room temperature. During the cooling process, argon gas with a purity of 99.99% (volume fraction) was continuously introduced into the furnace as a protective gas. Once the temperature inside the reduction furnace had dropped to room temperature, the crucible was quickly removed and placed in a distillation furnace, and the furnace lid was tightly closed. Set the distillation furnace sealing ring, open the inlet and outlet valves of the distillation furnace, and introduce 99.99% pure argon gas into the furnace for 60 minutes. After the gas introduction is complete, turn on the vacuum pump to evacuate the furnace until the vacuum level reaches 20 Pa. Then, raise the temperature of the distillation furnace to 900℃ at a heating rate of 5℃ / min and hold at this temperature for 600 minutes, maintaining the vacuum level of the furnace at 5 Pa throughout the heating and holding process. After the holding period, stop the vacuum pump and allow the furnace to cool down naturally. During the cooling process, introduce 99.99% pure argon gas as a protective gas into the furnace, waiting for the material in the furnace to cool down. After cooling to room temperature, the sponge vanadium product, totaling 1744g, was removed from the crucible. The purity (mass fraction) of the sponge vanadium was 99.900%, and the impurities were: O 0.058%, N 0.005%, C 0.007%, Al 0.002%, Cl 0.010%, Si 0.002%, Fe 0.004%, and Cr 0.012%. 1000g of sponge vanadium was placed in an electron beam furnace, and the vacuum level inside the furnace was controlled at 1×10⁻⁶. -2The vanadium was refined at 2000℃. After refining, 99.99% pure argon gas was introduced into the furnace as a protective gas to cool it down. After the furnace temperature 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 were 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%.

[0050] Example 2:

[0051] In a vertical vacuum reduction furnace with resistance wire heating in the bottom reaction zone and circulating cooling water cooling in the top feeding zone, 2104g of magnesium blocks (5-10mm in diameter, 99.95wt.% purity) were added to the corundum crucible at the bottom of the empty reduction furnace. The furnace sealing ring was tightened, the inlet and outlet pipes were connected, the inlet valve was closed, the outlet valve was opened, and the vacuum pump was turned on to exhaust gas. Once the vacuum level in the reduction furnace reached 50Pa, the vacuum pump was turned off. The inlet valve was then opened, and 99.99% pure argon gas was introduced into the furnace as a protective gas. The furnace was heated to 850℃ and held at that temperature. 9200g of 99.95% pure vanadium trichloride was gradually added to the crucible at the bottom of the furnace using a feeding device. During the feeding process, the furnace temperature fluctuated between 850-980℃. After the feeding was completed, the furnace was held at the set temperature of 850℃ for 120 minutes. During the feeding and holding process, 99.99% pure argon gas (volume fraction) is continuously introduced into the furnace as a protective gas. After the holding period, the furnace is allowed to cool naturally, allowing the material in the crucible to cool to room temperature. During the cooling process, 99.99% pure argon gas (volume fraction) is continuously introduced into the furnace as a protective gas. Once the temperature inside the reduction furnace has dropped to room temperature, the crucible is quickly removed and placed in a distillation furnace. The distillation furnace sealing ring is tightened, and the inlet and outlet valves are opened to introduce 99.99% pure argon gas (volume fraction) into the distillation furnace for 60 minutes. After the gas introduction is completed, the vacuum pump of the distillation furnace is turned on to evacuate the furnace until the vacuum level reaches 50 Pa. Then, at a heating rate of 10 °C / min, the temperature of the distillation furnace is raised to 1100 °C and held at this temperature for 240 minutes. During the heating and holding process, the vacuum level inside the distillation furnace is maintained at 1 × 10⁻⁶ Pa. -2Pa; After the heat preservation is completed, the vacuum pump stops evacuating the gas, and the distillation furnace cools down naturally. During the cooling process, argon gas with a purity (volume fraction) of 99.99% is introduced into the furnace as a protective gas. After the material in the distillation furnace cools to room temperature, the sponge vanadium product in the crucible is taken out, totaling 2684g. The purity (mass fraction) of the sponge vanadium is 99.926%, and the impurities are: O content (mass fraction) 0.041%, N content (mass fraction) 0.004%, C content (mass fraction) 0.006%, Al content (mass fraction) 0.003%, Cl content (mass fraction) 0.008%, Si content (mass fraction) 0.001%, Fe content (mass fraction) 0.003%, and Cr content (mass fraction) 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 The vanadium was refined at 3000℃. After refining, 99.99% pure argon gas was introduced into the furnace as a protective gas to cool it down. After the furnace temperature 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 were: O content (mass fraction) 0.003%, N content (mass fraction) 0.002%, C content (mass fraction) 0.002%, Al (below the detection limit) and Cl (below the detection limit) were not detected, Si content (mass fraction) 0.001%, Fe content (mass fraction) 0.001%, and Cr content (mass fraction) 0.001%.

[0052] Example 3:

[0053] In a vertical vacuum reduction furnace with resistance wire heating in the bottom reaction zone and circulating cooling water cooling in the top feeding zone, 2976g of magnesium blocks with a diameter of 5-10mm and a purity of 99.95wt.% were added to the corundum crucible at the bottom of the empty reduction furnace. The furnace sealing ring was tightened, the inlet and outlet pipes were connected, the inlet valve of the reduction furnace was closed, the outlet valve was opened, and the vacuum pump was turned on to exhaust gas. When the vacuum degree in the reduction furnace reached 100Pa, the vacuum pump was turned off. The inlet valve of the reduction furnace was opened, and argon gas with a purity (volume fraction) of 99.99% was introduced into the furnace as a protective gas. The reduction furnace was heated to 950℃ and held at that temperature. The material was fed to the bottom of the reduction furnace through the feeding device. 8400g of vanadium dichloride with a purity of 99.95% (mass fraction) was gradually added to the crucible. During the addition process, the furnace temperature fluctuated between 950-1060℃. After the addition was completed, the furnace was held at a set temperature of 950℃ for 240 minutes. During the addition and holding process, argon gas with a purity of 99.99% (volume fraction) was continuously introduced into the furnace as a protective gas. After the holding period, the furnace was allowed to cool naturally, allowing the material in the crucible to cool to room temperature along with the furnace. During the cooling process, argon gas with a purity of 99.99% (volume fraction) was continuously introduced into the furnace as a protective gas. Once the temperature inside the reduction furnace had dropped to room temperature, the crucible was quickly removed and placed in a distillation furnace, and the furnace was tightly sealed. Set the sealing ring of the distillation furnace, open the inlet and outlet valves, and introduce 99.99% pure argon gas into the furnace for 60 minutes. After the gas introduction is complete, turn on the vacuum pump to evacuate the furnace until the vacuum level reaches 10 Pa. Then, raise the furnace temperature to 1200℃ at a heating rate of 15℃ / min and hold at this temperature for 30 minutes, maintaining the vacuum level at 0.1 Pa throughout the heating and holding process. After the holding period, stop the vacuum pump and allow the furnace to cool naturally. During the cooling process, introduce 99.99% pure argon gas as a protective gas into the furnace until the gas level reaches 10 Pa. After the material cooled to room temperature, the sponge vanadium product, totaling 3192g, was removed from the crucible. The purity (mass fraction) of the sponge vanadium was 99.919%, and the impurities were: O 0.048%, N 0.005%, C 0.007%, Al 0.001%, Cl 0.006%, Si 0.002%, Fe 0.005%, and Cr 0.007%. 2500g of sponge vanadium was placed in an electron beam furnace, and the vacuum level inside the furnace was controlled at 5 × 10⁻⁶. -3Pa was refined at 2500℃. After refining, 99.99% pure argon gas was introduced into the furnace as a protective gas to cool it down. After the furnace temperature 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 were: O content (mass fraction) 0.008%, N content (mass fraction) 0.002%, C content (mass fraction) 0.004%, Al (below the detection limit) and Cl (below the detection limit) were not detected, Si content (mass fraction) 0.001%, Fe content (mass fraction) 0.003%, and Cr content (mass fraction) 0.002%.

[0054] This invention employs a novel metallothermic reduction-distillation method using chlorides to prepare high-purity sponge vanadium products with a purity (mass fraction) exceeding 99.9%. Further electron beam refining yields metallic vanadium products with a purity of 99.95%-99.99%. Compared to traditional methods involving the metallothermic reduction of vanadium oxides to prepare crude metallic vanadium and subsequent multi-stage refining, this method offers advantages such as a shorter process flow, milder process conditions, and higher product purity. Furthermore, electrolysis converts magnesium chloride byproducts into metallic magnesium and chlorine, achieving magnesium and chlorine recycling (magnesium is recycled to the reduction stage, and chlorine is used to prepare upstream vanadium chloride raw materials). This facilitates the low-cost preparation of high-purity metallic vanadium and enhances its application feasibility.

[0055] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0056] It should be understood that, as used herein, the singular form “a” is intended to include the plural form 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 of one or more of the associated listed items.

[0057] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0058] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the 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, purge the air from the furnace, and then introduce protective gas; b. Heat the reduction furnace to the maximum temperature, then gradually add vanadium chloride to the bottom crucible. After the addition is complete, keep the furnace at the maximum temperature and continuously introduce protective gas. After the furnace is kept at the maximum temperature, cool it down to room temperature. c. Remove the crucible and place it in the distillation furnace. Tighten the sealing ring of the distillation furnace and evacuate it. Open the gas inlet valve and gas outlet valve of the distillation furnace and introduce protective gas into the distillation furnace. d. Stop supplying protective gas into the distillation furnace, turn on the vacuum pump to evacuate the gas, and set the heating and holding programs for the distillation furnace; e. After the heat preservation is completed, the vacuum pump stops pumping air, the protective gas is introduced into the furnace again, and the material in the distillation furnace is cooled to room temperature. The product in the crucible is then removed. f. Place the product in a crucible inside an electron beam furnace, evacuate, heat and melt. After melting, introduce protective gas into the electron beam furnace. After cooling to room temperature, obtain the sponge vanadium product.

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 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 venting, the sealing ring of the vertical vacuum reduction furnace is tightened, the air inlet and exhaust pipes 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 vent to a vacuum level of less than 100 Pa.

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 metallic magnesium, metallic aluminum, and metallic calcium; the crucible is any one of corundum crucible and 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 to 2 / 3 of the theoretical amount of vanadium chloride required for the reaction of vanadium chloride and magnesium to produce metallic vanadium.

6. The method for preparing and purifying high-purity sponge vanadium according to claim 5, characterized in that, The vanadium chloride has a purity of 99.9% or higher, 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 to not exceed 150℃ during the feeding process, and the furnace is kept warm for 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 gas until the vacuum level inside the distillation furnace reaches below 50 Pa before starting the next heating step. During the heating and holding process, the vacuum level inside the distillation furnace is (1×10⁻⁶ Pa). -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 30–600 min.

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, with a temperature of 2000–3000℃.

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