High-purity vanadium metal based on vanadium shale and a preparation method thereof

Abstract

The present application relates to a kind of high-purity metal vanadium based on vanadium shale and its preparation method.The technical scheme is: vanadium shale acid leaching liquid and sodium chlorate are reacted, the mixture of obtained vanadium-containing precipitate and chlorination agent is subjected to chlorination reaction to obtain vanadyl trichloride liquid;vanadyl trichloride liquid is mixed with vanadium deposition agent and then mixed with graphite powder, grinded, briquetted, sintered under the conditions of nitrogen atmosphere and 1000~1500℃, to obtain vanadium carbon nitrogen oxygen solid solution.Eutectic salt is pre-melted in vacuum, mixed with promoter, mixed, and kept at 600~800℃ for 1~5h to obtain vanadium-containing electrolyte;the vanadium carbon nitrogen oxygen solid solution is used as soluble anode, constant potential electrolysis is carried out under the conditions of argon atmosphere and 2.0~3.0V for 6~24h, and the deposition product obtained from auxiliary electrode is high-purity metal vanadium based on vanadium shale.The present application has the characteristics of low energy consumption, simple process flow, high electrolysis efficiency and environmental friendliness, and the product prepared by the method has high purity.

Description

Technical Field

[0001] This invention belongs to the field of vanadium metal preparation technology. Specifically, it relates to a high-purity metallic vanadium based on vanadium shale and its preparation method. Background Technology

[0002] Vanadium is an important strategic rare metal, possessing excellent physical and chemical properties such as high strength, corrosion resistance, and high-temperature resistance. It has irreplaceable application value in key industrial fields such as metallurgical alloy modification, aerospace equipment manufacturing, new energy storage, and fine chemicals, resulting in consistently strong industrial demand. Vanadium shale is a unique vanadium-bearing mineral resource with considerable reserves in my country and is an important raw material for the production of metallic vanadium. Therefore, the extraction of high-purity metallic vanadium from vanadium shale has received considerable attention.

[0003] The patented technology, "A Method for Preparing Metallic Vanadium" (CN121976253A), uses V₂O₅ as raw material for dehydration under vacuum conditions. The dehydrated V₂O₅ is then placed in a molten salt electrolysis system as the cathode, with graphite as the anode, for an electrolytic reduction reaction. The molten salt electrolysis system consists of a mixed molten salt composed of sodium chloride and potassium chloride. The temperature of the electrolytic reduction reaction is controlled between 600℃ and 800℃, and the reaction time is 2 to 4 hours. After the reaction, the reaction product is cooled to room temperature, separated, and washed to obtain metallic vanadium. The obtained metallic vanadium is then annealed in a hydrogen atmosphere at 900℃ to 1000℃ for 1 to 3 hours to obtain high-purity metallic vanadium. While this method effectively extracts metallic vanadium, it consumes a large amount of energy, has a complex process flow, and low electrolysis efficiency.

[0004] The patented technology, "A Method for Preparing Metallic Vanadium by Metal Thermal Reduction in Molten Salt Medium" (CN119843080A), involves reducing V₂O₅ to low-valence vanadium oxide, reacting it with a reducing agent and a molten salt mixture, and then calcining it at high temperature in a sealed container. After holding at this temperature, the reaction product is acid-washed and filtered to obtain elemental metallic vanadium. The elemental metallic vanadium is then boiled in hydrochloric acid solution to obtain metallic vanadium. Although this method has a simple preparation process, readily available raw materials, and relatively low cost, the introduction of acid washing and filtration results in low vanadium recovery and is environmentally unfriendly.

[0005] The patented technology, "A Method for Preparing Metallic Vanadium Based on Vanadium Shale" (CN118704046A), involves adding sodium chlorate to an acid leaching solution of vanadium shale, adjusting the pH and temperature of the system, and stirring the reaction. After cooling and solid-liquid separation, a vanadium-containing precipitate is obtained. The vanadium-containing precipitate is mixed with a chlorinating agent to prepare a raw material, which is then subjected to a chlorination reaction at 150-190℃ under a protective atmosphere to obtain vanadium oxychloride liquid, which is then used to prepare vanadium trichloride. Mineral oil is added to the vanadium oxychloride liquid and mixed thoroughly. After a constant-temperature reaction, a vanadium trichloride mixture is obtained. Alcohol is added, and the mixture is allowed to stand and separate to obtain a clear liquid. The clear liquid is then dried under high-temperature vacuum to obtain vanadium trichloride powder. Finally, molten salt electrolysis is performed: the chloride additive is first vacuum pre-melted, then vanadium trichloride is mixed in a certain proportion to prepare an electrolyte. After heat treatment, electrolysis is performed at a constant potential under an argon atmosphere and a voltage of 2.0-3.0V, ultimately yielding metallic vanadium at the cathode. However, the purity of the metallic vanadium obtained by this technology is relatively low.

[0006] In summary, existing methods for preparing metallic vanadium suffer from technical drawbacks such as high energy consumption, complex processes, low electrolysis efficiency, environmental unfriendliness, and low purity. Summary of the Invention

[0007] The present invention aims to overcome the defects of the prior art and provides a method for preparing metallic vanadium based on vanadium shale that is energy-efficient, simple in process, highly efficient in electrolysis, and environmentally friendly. The metallic vanadium prepared by this method is of high purity based on vanadium shale.

[0008] To achieve the above objectives, the specific steps of the technical solution adopted by the present invention are as follows: Step 1 The vanadium shale acid leaching solution is prepared with a vanadium:sodium chlorate molar ratio of 1:1 to 1.2, mixed, and pretreated to obtain a vanadium-containing precipitate.

[0009] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:1 to 4 with chlorinating agent.

[0010] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0011] Step 2 Prepare the mixture by mixing vanadium oxychloride liquid and vanadium precipitant at a molar ratio of 1:0.6~1.25, allowing it to stand, and obtain vanadium-containing precipitate A.

[0012] The vanadium-containing precipitate A and graphite powder are prepared by mixing, drying, grinding, and pressing into briquettes at a molar ratio of 1:0.8~1.2 to obtain vanadium-containing precipitate B.

[0013] Vanadium-containing precipitate B was placed in a tube furnace and sintered for 2-8 hours under a nitrogen atmosphere and at 1000-1500℃ to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0014] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 2-6 hours under a vacuum of 0.01-0.025 MPa and a temperature of 350-500℃ to obtain the pre-melted eutectic salt.

[0015] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 0.5 to 2:100 to obtain vanadium-containing electrolyte A.

[0016] Vanadium-containing electrolyte A is placed in a molten salt electrolysis furnace and kept at 600~800℃ for 1~5 hours to obtain vanadium-containing electrolyte B.

[0017] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 6 to 24 hours under an argon atmosphere and at 2.0 to 3.0 V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0018] The vanadium concentration in the vanadium shale acid leaching solution is 1~5 g / L.

[0019] The pretreatment process is as follows: first, adjust the pH value of the mixture to 2-5, then stir at 50-80℃ for 20-40 minutes, cool, and separate the solid and liquid.

[0020] The chlorinating agent is aluminum chloride, or a mixture of aluminum chloride and zinc chloride, or a mixture of aluminum chloride and sodium chloride.

[0021] The chlorination reaction process is as follows: first, nitrogen or argon gas is introduced, then the temperature is maintained at 150~190℃ for 1~3 hours, followed by condensation.

[0022] The vanadium precipitation agent is melamine or ammonium chloride solution.

[0023] The eutectic salt is a mixture of lithium chloride and potassium chloride, or a mixture of sodium chloride and potassium chloride, or a mixture of calcium chloride, lithium chloride, and potassium chloride.

[0024] The accelerator is vanadium dichloride, vanadium trichloride, potassium fluoride, a mixture of vanadium dichloride and potassium fluoride, or a mixture of vanadium trichloride and potassium fluoride.

[0025] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a tungsten electrode or a platinum electrode; the reference electrode is a high-purity graphite electrode, a tungsten electrode, a molybdenum electrode, or a silver and saturated silver chloride electrode.

[0026] By employing the above method, the present invention has the following advantages compared with the prior art: 1. This invention uses vanadium oxychloride liquid obtained through chlorination distillation as the core raw material to further prepare a vanadium-carbon-nitrogen-oxygen solid solution, which is then used as the anode material for molten salt electrolysis. Compared with existing processes for preparing metallic vanadium by molten salt electrolysis, this invention fundamentally optimizes the anode reaction mechanism. The C, N, and O elements contained in the vanadium-carbon-nitrogen-oxygen solid solution undergo oxidation reactions at the anode during electrolysis, generating CO, CO2, and N2 gases respectively. These gases can directly escape from the electrolysis system without leaving metallic impurities in the molten salt electrolyte, thus avoiding the environmental pollution caused by chlorine gas. Therefore, the process is simple and environmentally friendly.

[0027] 2. This invention preferably uses a mixture of anhydrous sodium chloride and potassium chloride as the eutectic salt electrolyte. Compared with the prior art that uses a single chloride or other mixed chlorides as the eutectic salt, this has significant thermodynamic advantages. The subsequent electrolysis temperature can be maintained at 600~800℃ to meet the reaction requirements, which is lower than the electrolysis temperature of existing molten salt electrolysis processes. Therefore, this invention has a low electrolysis temperature and low energy consumption.

[0028] 3. The vanadium-carbon-nitrogen-oxygen solid solution selected in this invention exhibits excellent fusion with the promoter in the electrolyte. This characteristic offers significant advantages over existing processes that add or do not add other vanadium ions. On one hand, the improved fusion effect makes the chemical properties of the electrolyte system more stable, effectively avoiding problems such as electrolyte stratification and sudden drops in vanadium ion concentration during electrolysis, ensuring the continuous and stable progress of the electrolysis reaction. On the other hand, the concentration of vanadium ions in the electrolyte can be maintained at a high level under this system, providing sufficient raw materials for the deposition of vanadium at the cathode, significantly improving the cathode deposition effect, increasing electrolysis efficiency, and resulting in a high recovery rate of metallic vanadium. Furthermore, it contains fewer internal impurity ions, maintaining a purity of 99.0% to 99.9%.

[0029] Therefore, this invention has the characteristics of low energy consumption, simple process flow, high electrolysis efficiency and environmental friendliness, and the metallic vanadium based on vanadium shale prepared by this method has high purity. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. This is not intended to limit the scope of protection of the invention.

[0031] A high-purity metallic vanadium based on vanadium shale and its preparation method. The steps of the preparation method described in this specific embodiment are as follows: Step 1 The vanadium shale acid leaching solution is prepared with a vanadium:sodium chlorate molar ratio of 1:1 to 1.2, mixed, and pretreated to obtain a vanadium-containing precipitate.

[0032] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:1 to 4 with chlorinating agent.

[0033] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0034] Step 2 Prepare the mixture by mixing vanadium oxychloride liquid and vanadium precipitant at a molar ratio of 1:0.6~1.25, allowing it to stand, and obtain vanadium-containing precipitate A.

[0035] The vanadium-containing precipitate A and graphite powder are prepared by mixing, drying, grinding, and pressing into briquettes at a molar ratio of 1:0.8~1.2 to obtain vanadium-containing precipitate B.

[0036] Vanadium-containing precipitate B was placed in a tube furnace and sintered for 2-8 hours under a nitrogen atmosphere and at 1000-1500℃ to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0037] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 2-6 hours under a vacuum of 0.01-0.025 MPa and a temperature of 350-500℃ to obtain the pre-melted eutectic salt.

[0038] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 0.5 to 2:100 to obtain vanadium-containing electrolyte A.

[0039] Vanadium-containing electrolyte A is placed in a molten salt electrolysis furnace and kept at 600~800℃ for 1~5 hours to obtain vanadium-containing electrolyte B.

[0040] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 6 to 24 hours under an argon atmosphere and at 2.0 to 3.0 V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0041] The vanadium concentration in the vanadium shale acid leaching solution is 1~5 g / L.

[0042] The pretreatment process is as follows: first, adjust the pH value of the mixture to 2-5, then stir at 50-80℃ for 20-40 minutes, cool, and separate the solid and liquid.

[0043] The chlorinating agent is aluminum chloride, or a mixture of aluminum chloride and zinc chloride, or a mixture of aluminum chloride and sodium chloride.

[0044] The chlorination reaction process is as follows: first, nitrogen or argon gas is introduced, then the temperature is maintained at 150~190℃ for 1~3 hours, followed by condensation.

[0045] The vanadium precipitation agent is melamine or ammonium chloride solution.

[0046] The eutectic salt is a mixture of lithium chloride and potassium chloride, or a mixture of sodium chloride and potassium chloride, or a mixture of calcium chloride, lithium chloride, and potassium chloride.

[0047] The accelerator is vanadium dichloride, vanadium trichloride, potassium fluoride, a mixture of vanadium dichloride and potassium fluoride, or a mixture of vanadium trichloride and potassium fluoride.

[0048] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a tungsten electrode or a platinum electrode; the reference electrode is a high-purity graphite electrode, a tungsten electrode, a molybdenum electrode, or a silver and saturated silver chloride electrode.

[0049] Example 1 A high-purity metallic vanadium based on vanadium shale and its preparation method. The steps of the preparation method described in this embodiment are as follows: Step 1 The vanadium to sodium chlorate molar ratio in the vanadium shale acid leaching solution is 1:1. The mixture is prepared and pretreated to obtain a vanadium-containing precipitate.

[0050] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:1 to chlorinating agent.

[0051] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0052] Step 2 The vanadium trichloride liquid and vanadium precipitant were prepared at a molar ratio of 1:0.6, mixed, and allowed to stand to obtain vanadium-containing precipitate A.

[0053] Vanadium-containing precipitate A and graphite powder were prepared in a molar ratio of 1:0.8, mixed, dried, ground, and briquetted to obtain vanadium-containing precipitate B.

[0054] Vanadium-containing precipitate B was placed in a tube furnace and sintered at 1000°C for 2 hours under a nitrogen atmosphere to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0055] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 2 hours under a vacuum of 0.025 MPa and a temperature of 350°C to obtain the pre-melted eutectic salt.

[0056] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 0.5:100 to obtain vanadium-containing electrolyte A.

[0057] Vanadium-containing electrolyte A was placed in a molten salt electrolysis furnace and kept at 600℃ for 1 hour to obtain vanadium-containing electrolyte B.

[0058] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 6 hours under an argon atmosphere and at 2.0V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0059] The vanadium concentration in the vanadium shale acid leaching solution is 1 g / L.

[0060] The pretreatment process is as follows: first, adjust the pH value of the mixture to 5, then stir at 50°C for 20 minutes, cool, and separate the solid and liquid.

[0061] The chlorinating agent is aluminum chloride.

[0062] The chlorination reaction process is as follows: first, nitrogen gas is introduced, then the temperature is maintained at 150°C for 1 hour, and then condensed.

[0063] The vanadium precipitation agent is melamine.

[0064] The eutectic salt is a mixture of lithium chloride and potassium chloride.

[0065] The accelerator is vanadium dichloride.

[0066] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a tungsten electrode; the reference electrode is a high-purity graphite electrode.

[0067] Example 2 A high-purity metallic vanadium based on vanadium shale and its preparation method. The steps of the preparation method described in this embodiment are as follows: Step 1 The vanadium shale acid leaching solution was prepared with a vanadium:sodium chlorate molar ratio of 1:1.05, mixed, and pretreated to obtain a vanadium-containing precipitate.

[0068] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:2 to vanadium in the chlorinating agent.

[0069] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0070] Step 2 The vanadium trichloride liquid and vanadium precipitant were prepared at a molar ratio of 1:0.8, mixed, and allowed to stand to obtain vanadium-containing precipitate A.

[0071] Vanadium-containing precipitate A and graphite powder were prepared in a molar ratio of 1:0.9, mixed, dried, ground, and briquetted to obtain vanadium-containing precipitate B.

[0072] Vanadium-containing precipitate B was placed in a tube furnace and sintered at 1150°C for 4 hours under a nitrogen atmosphere to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0073] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 3 hours under a vacuum of 0.02 MPa and a temperature of 400°C to obtain the pre-melted eutectic salt.

[0074] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 1:100 to obtain vanadium-containing electrolyte A.

[0075] Vanadium-containing electrolyte A was placed in a molten salt electrolysis furnace and kept at 650℃ for 2 hours to obtain vanadium-containing electrolyte B.

[0076] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 10 hours under an argon atmosphere and at 2.3V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0077] The vanadium concentration in the vanadium shale acid leaching solution is 2 g / L.

[0078] The pretreatment process is as follows: first, adjust the pH value of the mixture to 4, then stir at 60°C for 25 minutes, cool, and separate the solid and liquid.

[0079] The chlorinating agent is a mixture of aluminum chloride and zinc chloride.

[0080] The chlorination reaction process is as follows: first, argon gas is introduced, then the temperature is maintained at 160°C for 2 hours, and then condensed.

[0081] The vanadium precipitation agent is an ammonium chloride solution.

[0082] The eutectic salt is a mixture of calcium chloride, lithium chloride, and potassium chloride.

[0083] The accelerator is vanadium trichloride.

[0084] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a platinum electrode; the reference electrode is a tungsten electrode.

[0085] Example 3 A high-purity metallic vanadium based on vanadium shale and its preparation method. The steps of the preparation method described in this embodiment are as follows: Step 1 The vanadium to sodium chlorate molar ratio in the vanadium shale acid leaching solution is 1:1.1. The mixture is prepared and pretreated to obtain a vanadium-containing precipitate.

[0086] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:3 to chlorinating agent.

[0087] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0088] Step 2 The vanadium trichloride liquid and vanadium precipitant were mixed at a molar ratio of 1:1, allowed to stand, and vanadium-containing precipitate A was obtained.

[0089] Vanadium-containing precipitate A and graphite powder were mixed, dried, ground, and pressed into briquettes to obtain vanadium-containing precipitate B.

[0090] Vanadium-containing precipitate B was placed in a tube furnace and sintered at 1300°C for 6 hours under a nitrogen atmosphere to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0091] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 4 hours under a vacuum of 0.015 MPa and a temperature of 450°C to obtain the pre-melted eutectic salt.

[0092] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 1.5:100 to obtain vanadium-containing electrolyte A.

[0093] Vanadium-containing electrolyte A was placed in a molten salt electrolysis furnace and kept at 750℃ for 3 hours to obtain vanadium-containing electrolyte B.

[0094] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 14 hours under an argon atmosphere and at 2.7V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0095] The vanadium concentration in the vanadium shale acid leaching solution is 3 g / L.

[0096] The pretreatment process is as follows: first, adjust the pH value of the mixture to 3, then stir at 70°C for 30 minutes, cool, and separate the solid and liquid.

[0097] The chlorinating agent is a mixture of aluminum chloride and sodium chloride.

[0098] The chlorination reaction process is as follows: first, argon gas is introduced, then the temperature is maintained at 170°C for 3 hours, and then condensed.

[0099] The vanadium precipitation agent is melamine.

[0100] The eutectic salt is a mixture of sodium chloride and potassium chloride.

[0101] The accelerator is a mixture of vanadium dichloride and potassium fluoride.

[0102] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a tungsten electrode; the reference electrode is a silver and saturated silver chloride electrode.

[0103] Example 4 A high-purity metallic vanadium based on vanadium shale and its preparation method. The steps of the preparation method described in this embodiment are as follows: Step 1 The vanadium shale acid leaching solution was prepared with a vanadium:sodium chlorate molar ratio of 1:1.15, mixed, and pretreated to obtain a vanadium-containing precipitate.

[0104] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:4 to chlorinating agent.

[0105] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0106] Step 2 The vanadium trichloride liquid and vanadium precipitant were prepared at a molar ratio of 1:0.9, mixed, and allowed to stand to obtain vanadium-containing precipitate A.

[0107] Vanadium-containing precipitate A and graphite powder were mixed, dried, ground, and pressed into briquettes to obtain vanadium-containing precipitate B.

[0108] Vanadium-containing precipitate B was placed in a tube furnace and sintered at 1400°C for 8 hours under a nitrogen atmosphere to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0109] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 5 hours under a vacuum of 0.01 MPa and a temperature of 480°C to obtain the pre-melted eutectic salt.

[0110] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 2:100 to obtain vanadium-containing electrolyte A.

[0111] Vanadium-containing electrolyte A was placed in a molten salt electrolysis furnace and kept at 700℃ for 4 hours to obtain vanadium-containing electrolyte B.

[0112] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 18 hours under an argon atmosphere and at 3.0V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0113] The vanadium concentration in the vanadium shale acid leaching solution is 4 g / L.

[0114] The pretreatment process is as follows: first, adjust the pH value of the mixture to 2, then stir at 80°C for 35 minutes, cool, and separate the solid and liquid.

[0115] The chlorinating agent is a mixture of aluminum chloride and zinc chloride.

[0116] The chlorination reaction process is as follows: first, nitrogen gas is introduced, then the temperature is maintained at 180°C for 2.5 hours, and then condensed.

[0117] The vanadium precipitation agent is an ammonium chloride solution.

[0118] The eutectic salt is a mixture of lithium chloride and potassium chloride.

[0119] The accelerator is a mixture of vanadium trichloride and potassium fluoride.

[0120] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a platinum electrode; the reference electrode is a molybdenum electrode.

[0121] Example 5 A high-purity metallic vanadium based on vanadium shale and its preparation method. The steps of the preparation method described in this embodiment are as follows: Step 1 The vanadium to sodium chlorate molar ratio in the vanadium shale acid leaching solution is 1:1.2. The mixture is prepared and pretreated to obtain a vanadium-containing precipitate.

[0122] The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of 1:2.5 to vanadium in the chlorinating agent.

[0123] The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to chlorination to obtain vanadium oxychloride liquid.

[0124] Step 2 The vanadium trichloride liquid and vanadium precipitant were prepared at a molar ratio of 1:1.25, mixed, and allowed to stand to obtain vanadium-containing precipitate A.

[0125] The vanadium-containing precipitate A and graphite powder were prepared in a molar ratio of 1:1.2, mixed, dried, ground, and pressed into briquettes to obtain vanadium-containing precipitate B.

[0126] Vanadium-containing precipitate B was placed in a tube furnace and sintered at 1500°C for 6 hours under a nitrogen atmosphere to obtain a vanadium-carbon-nitrogen-oxygen solid solution.

[0127] Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 6 hours under a vacuum of 0.018 MPa and a temperature of 500°C to obtain the pre-melted eutectic salt.

[0128] The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 1.25:100 to obtain vanadium-containing electrolyte A.

[0129] Vanadium-containing electrolyte A was placed in a molten salt electrolysis furnace and kept at 800℃ for 5 hours to obtain vanadium-containing electrolyte B.

[0130] The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 24 hours under an argon atmosphere and at 2.5V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

[0131] The vanadium concentration in the vanadium shale acid leaching solution is 5 g / L.

[0132] The pretreatment process is as follows: first, adjust the pH value of the mixture to 3.5, then stir at 65°C for 40 minutes, cool, and separate the solid and liquid.

[0133] The chlorinating agent is aluminum chloride.

[0134] The chlorination reaction process is as follows: first, nitrogen gas is introduced, then the temperature is maintained at 190°C for 1.5 hours, and then condensed.

[0135] The vanadium precipitation agent is melamine.

[0136] The eutectic salt is a mixture of calcium chloride, lithium chloride, and potassium chloride.

[0137] The accelerator is potassium fluoride.

[0138] The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a platinum electrode; the reference electrode is a high-purity graphite electrode.

[0139] This specific implementation method has the following advantages compared with the prior art: 1. This specific embodiment uses vanadium oxychloride liquid obtained by chlorination distillation as the core raw material, and further prepares vanadium carbon nitrogen oxygen solid solution, which is then used as the anode material for molten salt electrolysis. Compared with existing processes for preparing metallic vanadium by molten salt electrolysis, this specific embodiment fundamentally optimizes the anode reaction mechanism. The C, N, and O elements contained in the vanadium carbon nitrogen oxygen solid solution undergo oxidation reactions at the anode during electrolysis, generating CO, CO2, and N2 gases, respectively. These gases can directly escape from the electrolysis system without producing metallic impurities in the molten salt electrolyte, thus avoiding the problem of chlorine pollution. Therefore, the process is simple and environmentally friendly.

[0140] 2. In this specific embodiment, a mixture of anhydrous sodium chloride and potassium chloride is preferred as the eutectic salt electrolyte. Compared with the prior art that uses a single chloride or other mixed chlorides as the eutectic salt, this has significant thermodynamic advantages. The subsequent electrolysis temperature can be maintained at 600~800℃ to meet the reaction requirements, which is lower than the electrolysis temperature of existing molten salt electrolysis processes. Therefore, this specific embodiment has a low electrolysis temperature and low energy consumption.

[0141] 3. The vanadium-carbon-nitrogen-oxygen solid solution selected in this specific embodiment exhibits excellent fusion with the promoter in the electrolyte. This characteristic offers significant advantages compared to existing processes that add or do not add other vanadium ions. On one hand, the improved fusion effect makes the chemical properties of the electrolyte system more stable, effectively avoiding problems such as electrolyte stratification and a sudden drop in vanadium ion concentration during electrolysis, ensuring the continuous and stable progress of the electrolysis reaction. On the other hand, the concentration of vanadium ions in the electrolyte can be maintained at a high level under this system, providing sufficient raw materials for the deposition of vanadium at the cathode, significantly improving the cathode deposition effect, increasing electrolysis efficiency, and resulting in a high recovery rate of metallic vanadium. Furthermore, it contains fewer internal impurity ions, maintaining a purity of 99.0% to 99.9%.

[0142] Therefore, this specific embodiment has the characteristics of low energy consumption, simple process flow, high electrolysis efficiency and environmental friendliness, and the metallic vanadium based on vanadium shale prepared by this method has high purity.

Claims

1. A method for preparing high-purity metallic vanadium based on vanadium shale, characterized in that, The preparation method is as follows: Step 1 The vanadium to sodium chlorate molar ratio in the vanadium shale acid leaching solution is 1:1 to 1.

2. The mixture is prepared and pretreated to obtain vanadium-containing precipitate. The raw materials for chlorination distillation are prepared by mixing vanadium in the vanadium-containing precipitate at a molar ratio of vanadium to chlorinating agent of 1:1 to 4. The chlorinated distillation feedstock is placed in a distillation apparatus and subjected to a chlorination reaction to obtain vanadium oxychloride liquid; Step 2 Prepare the vanadium trichloride liquid and vanadium precipitant at a molar ratio of 1:0.6~1.25, mix, and let stand to obtain vanadium-containing precipitate A; The vanadium-containing precipitate A and graphite powder are prepared in a molar ratio of 1:0.8~1.2, mixed, dried, ground, and pressed into briquettes to obtain vanadium-containing precipitate B. Vanadium-containing precipitate B was placed in a tube furnace and sintered for 2-8 hours under a nitrogen atmosphere and at 1000-1500℃ to obtain a vanadium-carbon-nitrogen-oxygen solid solution. Step 3 The eutectic salt is placed in an alumina crucible, and then the alumina crucible is placed in a molten salt electrolysis furnace and pre-melted for 2-6 hours under a vacuum of 0.01-0.025 MPa and a temperature of 350-500℃ to obtain the pre-melted eutectic salt. The accelerator and the pre-melted eutectic salt were mixed at a mass ratio of 0.5 to 2 to 100 to obtain vanadium-containing electrolyte A. Vanadium-containing electrolyte A is placed in a molten salt electrolysis furnace and kept at 600~800℃ for 1~5h to obtain vanadium-containing electrolyte B. The vanadium-carbon-nitrogen-oxygen solid solution is used as a soluble anode. The soluble anode, auxiliary electrode, and reference electrode are immersed together in the vanadium-containing electrolyte B and electrolyzed at a constant potential for 6 to 24 hours under an argon atmosphere and at 2.0 to 3.0 V. The deposition product obtained by the auxiliary electrode is high-purity metallic vanadium based on vanadium shale.

2. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The vanadium concentration in the vanadium shale acid leaching solution is 1~5 g / L.

3. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The pretreatment process is as follows: first, adjust the pH value of the mixture to 2-5, then stir at 50-80℃ for 20-40 minutes, cool, and separate the solid and liquid.

4. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The chlorinating agent is aluminum chloride, or a mixture of aluminum chloride and zinc chloride, or a mixture of aluminum chloride and sodium chloride.

5. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The chlorination reaction process is as follows: first, nitrogen or argon gas is introduced, then the temperature is maintained at 150~190℃ for 1~3 hours, followed by condensation.

6. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The vanadium precipitation agent is melamine or ammonium chloride solution.

7. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The eutectic salt is a mixture of lithium chloride and potassium chloride, or a mixture of sodium chloride and potassium chloride, or a mixture of calcium chloride, lithium chloride, and potassium chloride.

8. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The accelerator is vanadium dichloride, vanadium trichloride, potassium fluoride, a mixture of vanadium dichloride and potassium fluoride, or a mixture of vanadium trichloride and potassium fluoride.

9. The method for preparing high-purity metallic vanadium based on vanadium shale according to claim 1, characterized in that, The auxiliary electrode and the reference electrode are as follows: the auxiliary electrode is a tungsten electrode or a platinum electrode; the reference electrode is a high-purity graphite electrode, a tungsten electrode, a molybdenum electrode, or a silver and saturated silver chloride electrode.

10. A high-purity metallic vanadium based on vanadium shale, characterized in that, The high-purity metallic vanadium based on vanadium shale is prepared by the method for preparing high-purity metallic vanadium based on vanadium shale according to any one of claims 1 to 9.