A method for producing metallic tantalum by molten salt electrolysis

Abstract

The application relates to a method for preparing metallic tantalum by molten salt electrolysis, which comprises the following steps: taking an electrolytic cell containing an anode electrolysis chamber and a cathode electrolysis chamber, placing a liquid tantalum alloy at the bottom of the electrolytic cell for separating the anode electrolysis chamber and the cathode electrolysis chamber, respectively placing an anode and a cathode into the anode electrolysis chamber and the cathode electrolysis chamber, adding molten salt a into the anode electrolysis chamber and adding molten salt b into the cathode electrolysis chamber, adding raw material tantalum pentoxide into the anode electrolysis chamber, and then operating the electrolytic cell, so that CO and CO2 gas are generated at the anode and solid metallic tantalum is deposited at the cathode. The method for preparing metallic tantalum by molten salt electrolysis uses tantalum pentoxide as raw material, has low requirement on the purity of the raw material, can directly obtain high-purity metallic tantalum, and can intercept other impurities in the liquid tantalum alloy and the molten salt; the process flow is simple, efficient, energy-saving and continuous.

Description

Technical Field

[0001] This invention belongs to the field of tantalum metallurgy, and specifically relates to a method for preparing metallic tantalum by molten salt electrolysis. Background Technology

[0002] Tantalum is a rare metallic element with properties such as high melting point, low vapor pressure, good cold working performance, high chemical stability, strong resistance to acid and alkali corrosion, and high dielectric constant of surface oxide film. Moreover, tantalum metal and its alloys are important functional materials with significant applications in industries such as electronics, integrated circuits, tantalum iron, metallurgy, chemicals, cemented carbide, atomic energy, aerospace, strategic weapons, and medical devices.

[0003] Tantalum metal preparation processes can be divided into two categories: one category consists of methods that are currently industrially applied, including the tantalum oxide carbothermal reduction method, the potassium sodium fluorotantalate thermal reduction method, and the tantalum oxide molten salt electrolysis method; the other category consists of methods that are still in the laboratory research stage, including the tantalum oxide calcium thermal reduction method, the tantalum oxide solid-state electro-deoxidation method, and the tantalum oxide solid-state oxygen-permeable membrane method.

[0004] The carbothermic reduction of tantalum oxide is a process in which tantalum pentoxide is reduced to metallic tantalum using carbon under high-temperature vacuum conditions. The reduction process is as follows: Ta₂O₅ + 7C = 2TaC + 5CO; Ta₂O₅ + 12TaC = 7Ta₂C + 5CO; Ta₂O₅ + 5Ta₂C = 12Ta + 5CO. This production process is characterized by intermittent production, low mechanization, and high content of impurities C and O in the metal.

[0005] The basic principle of the potassium sodium fluorotantalate thermal reduction method is to prepare tantalum metal by reducing tantalum compounds with active metals such as alkali metals and alkaline earth metals. For example, the method for thermal reduction of potassium fluorotantalate with molten sodium salt disclosed in US Patent 3012877 has the chemical process K2TaF7 + 5Na = Ta + 2KF + 5NaF; Chinese Patent CN1169643C discloses a method for preparing ultrafine tantalum powder by reducing tantalum oxides with alkali metals in molten halides of alkali metals and alkaline earth metals, with the chemical process Ta2O5 + 5CaCl2 + 10Na = 2Ta + 10NaCl + 5CaO. These methods require the addition of inert salts (such as KCl, NaCl, KF, NaF, etc. halides) as diluents during the preparation of tantalum powder. This process has disadvantages such as a large demand for inert salts, the inability to recycle them, and the inability to maintain continuous production.

[0006] Furthermore, US Patent 6136062 discloses a method for preparing niobium powder and tantalum powder by reducing niobium oxide and tantalum oxide with magnesium. This method includes two reduction processes. The first stage is Mg + Ta₂O₅ = Mg + (Nb, Ta)O. x(x = 0.5 ~ 1.5); Second stage, (Nb,Ta)O x (x = 0.5~1.5) + Mg = Ta + MgO. The disadvantages of this method are: the tantalum metal has a high content of impurities Mg and O, the process is complex, and continuous production is not possible.

[0007] The traditional tantalum oxide molten salt electrolysis method uses a mixed molten salt of potassium fluorotantalate, potassium chloride, and sodium chloride as the electrolyte. Tantalum pentoxide, the raw material, is added to the electrolyte and undergoes a dissolution reaction. Tantalum ions are reduced on a nickel cathode to produce metallic tantalum, while oxygen ions are discharged on a graphite anode to release CO and CO2. However, this method requires high purity of the tantalum oxide raw material, and the resulting metallic tantalum product has a high content of impurity elements.

[0008] The reduction of tantalum pentoxide by calcium tantalum oxide is carried out in stages using a calcium chloride-calcium oxide mixed molten salt as the electrolyte. Through molten salt electrolysis, oxygen ions are discharged at the graphite anode to release CO and CO2, while calcium ions are reduced on the cathode grid to form liquid metallic calcium. The liquid metallic calcium then reduces the particulate tantalum pentoxide in the cathode grid to metallic tantalum. The reaction process is: Ta₂O₅ + 5Ca = 2Ta + 5CaO. However, the drawback of this method is that the product, tantalum metal, contains high levels of impurity elements O and C.

[0009] The core of the tantalum oxide solid-state electro-deoxidation method is to use solid tantalum oxide as the cathode and calcium chloride molten salt as the electrolyte. Through molten salt electrolysis, tantalum ions in the cathode are reduced in situ to metallic tantalum. Simultaneously, oxygen anions leave the cathode and enter the melt, migrating to the anode under the influence of the electric field and being oxidized to oxygen (when using a carbon anode, oxygen further reacts with carbon to produce CO and CO2). However, the tantalum oxide briquettes at the cathode are reduced gradually from the outside in, making oxygen diffusion increasingly difficult, resulting in low-oxygen-content tantalum. Furthermore, the product purity is limited by the purity of impurities in the raw materials.

[0010] The core of the tantalum oxide solid-state oxygen-permeable membrane method is to use solid tantalum oxide as the cathode, carbon-saturated copper liquid inside a yttrium oxide-stabilized zirconium oxide tube as the anode, and a magnesium oxide-magnesium fluoride mixed molten salt as the electrolyte. Through molten salt electrolysis, tantalum ions in the cathode are reduced in situ to metallic tantalum. Simultaneously, oxygen anions leave the cathode and enter the melt, diffusing through the solid-state oxygen-permeable membrane under the influence of an electric field to the anode where they are oxidized to oxygen (when using a carbon anode, oxygen further reacts with carbon to produce CO and CO2). This method avoids the problems of side reactions and high impurity content in the metal. However, it suffers from drawbacks such as short lifespan of the solid-state oxygen-permeable membrane and high manufacturing cost, making large-scale application difficult.

[0011] To overcome the above problems, the technical solution of this invention is proposed. Summary of the Invention

[0012] To address the problems existing in the prior art, this invention provides a method for preparing tantalum metal by molten salt electrolysis. The method uses tantalum pentoxide as the raw material, which not only has low requirements for raw material purity but also directly yields high-purity tantalum metal, while other impurities are retained in the liquid tantalum alloy and molten salt. The process is simple, highly efficient, energy-saving, and allows for continuous operation.

[0013] The present invention provides a method for preparing tantalum metal by molten salt electrolysis, comprising the following steps:

[0014] (1) Take an electrolytic cell containing an anode electrolytic chamber and a cathode electrolytic chamber, and place liquid tantalum alloy at the bottom of the electrolytic cell to separate the anode electrolytic chamber and the cathode electrolytic chamber. The anode and cathode are respectively placed in the anode electrolytic chamber and the cathode electrolytic chamber.

[0015] (2) Add molten salt a to the anode electrolysis chamber and molten salt b to the cathode electrolysis chamber;

[0016] (3) Add the raw material tantalum pentoxide to the anode electrolysis chamber, and then run the electrolysis cell with electricity. CO and CO2 gases are generated at the anode, and solid tantalum metal is deposited at the cathode.

[0017] The anode electrolysis chamber and cathode electrolysis chamber of the electrolytic cell are individually temperature controlled. The temperature control methods include the thermal effect of current, heating element heating, and water-cooled jacket cooling.

[0018] Preferably, in step (1), the liquid alloy is composed of tantalum and one or more of gold, platinum, nickel, iron, cobalt and manganese.

[0019] Preferably, in step (1), the cathode is a tantalum cathode, a tungsten cathode, or a molybdenum cathode.

[0020] Preferably, in step (1), the operating temperature of the electrolytic cell is 700–1800°C.

[0021] In step (2), the molten salt a is divided into two categories. The first category of molten salt a is composed of one or more of calcium chloride, barium chloride, strontium chloride, lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, and lanthanum chloride.

[0022] When using molten salt of type I a, the electrolysis principle is as follows:

[0023] When the electrolytic cell is powered on, tantalum pentoxide feedstock is added to the surface of the liquid alloy in the anode electrolysis chamber. Since it is insoluble in the molten salt of the anode electrolysis chamber, tantalum ions in the tantalum pentoxide feedstock are reduced to metallic tantalum in situ via electro-deoxidation and dissolve in the liquid alloy. Meanwhile, oxygen ions bound to tantalum move to the anode surface under the influence of the electric field and are oxidized to zero-valent oxygen, which then reacts with the anode carbon to generate CO and CO2, which escape. Simultaneously, tantalum atoms in the liquid alloy lose electrons at the interface and are oxidized to tantalum ions, which enter the molten salt of the cathode chamber. The tantalum ions in the molten salt of the cathode chamber move to the cathode surface under the influence of the electric field and are reduced to solid metallic tantalum.

[0024] The second type of molten salt a is composed of one of potassium fluorotantalate and sodium fluorotantalate, and one or more of potassium chloride, potassium fluoride, sodium chloride, sodium fluoride, lithium chloride, lithium fluoride, calcium chloride, and calcium fluoride.

[0025] When using molten salt type a, the electrolysis principle is as follows:

[0026] When the electrolytic cell is powered on, tantalum pentoxide feedstock is added to the anode electrolytic chamber and simultaneously dissolves in the molten salt within the chamber. Tantalum ions in the molten salt move to the liquid alloy interface under the influence of the electric field and are reduced to metallic tantalum, dissolving in the liquid alloy. Oxygen ions move to the anode surface under the influence of the electric field and are oxidized to zero-valent oxygen, then react with the anode carbon to generate CO and CO2, which escape. At the same time, tantalum atoms in the liquid alloy lose electrons at the liquid alloy interface and are oxidized to tantalum ions, entering the cathode molten salt. Meanwhile, tantalum ions in the cathode molten salt move to the cathode surface under the influence of the electric field and are reduced to solid metallic tantalum.

[0027] Preferably, in step (2), the molten salt b is composed of one of potassium fluorotantalate and sodium fluorotantalate, and one or more of sodium chloride, potassium chloride, lithium chloride, calcium chloride, barium chloride, lithium fluoride, sodium fluoride, and potassium fluoride.

[0028] Preferably, in step (3), the purity of tantalum pentoxide is ≥80%wt.

[0029] Preferably, in step (3), the anode is a graphite anode.

[0030] Preferably, in step (3), the anolyte current density during electrolysis is 0.01–2.0 A / cm². 2 .

[0031] The beneficial effects of this invention are as follows:

[0032] The method for preparing tantalum metal by molten salt electrolysis described in this invention uses tantalum pentoxide as raw material, which not only does not require high purity of raw material, but also can directly obtain high-purity tantalum metal, while other impurities are trapped in the liquid tantalum alloy and molten salt; the process is simple, efficient and energy-saving, and the operation is continuous. Attached Figure Description

[0033] 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 drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the electrolytic cell described in this invention.

[0035] Figure reference numerals:

[0036] 1-Anode; 2-Molten salt a; 3-Tantalum pentoxide; 4-Liquid tantalum alloy; 5-Molten salt b; 6-Cathode product tantalum; 7-Cathode; 8-Water-cooled jacket; 9-Insulation material; 10-Heating element; 11-Refractory material; I-Anode electrolysis chamber; II-Cathode electrolysis chamber Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0040] (1) A tantalum-gold alloy (10% wt tantalum, 90% wt gold) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous argon gas supply is maintained at a flow rate of 10 mL / min. The electrolytic cell is then heated to 1100℃ and held at that temperature for 1 hour to allow the tantalum-gold alloy in the electrolytic cell to completely melt into a liquid state. The formed liquid alloy divides the electrolytic cell into an anode electrolytic chamber and a cathode electrolytic chamber.

[0041] (2) NaCl (40 at%)-CaCl2 (60 at%) molten salt was used as the electrolyte in the anode electrolysis chamber of the electrolytic cell, and K2TaF7 (40% wt)-NaCl (40% wt)-KCl (20% wt) molten salt was used as the electrolyte in the cathode electrolysis chamber. Tantalum pentoxide (80% wt purity) was added to the liquid alloy interface in the anode electrolysis chamber. The molten salt temperature in both the anode and cathode electrolysis chambers was controlled at 800℃, and the liquid alloy temperature at the bottom of the electrolytic cell was controlled at 1100℃. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt in the anode electrolysis chamber, and the tantalum cathode was inserted into the molten salt in the cathode electrolysis chamber. Electrolysis was performed for 12 hours, with the anode current density controlled at 0.01 A / cm². 2 Tantalum metal was obtained as a cathode product in the cathode electrolysis chamber, and the purity of tantalum was found to be 99.95%.

[0042] Example 2

[0043] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0044] (1) A tantalum-gold alloy (10% wt tantalum, 90% wt gold) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous argon gas supply is maintained at a flow rate of 20 mL / min. The electrolytic cell is then heated to 1100℃ and held at that temperature for 2 hours to allow the tantalum-gold alloy in the electrolytic cell to completely melt into a liquid state. The resulting liquid alloy divides the electrolytic cell into an anode electrolysis chamber and a cathode electrolysis chamber.

[0045] (2) A K2TaF7 (17% wt)-KF (27% wt)-KCl (56% wt) molten salt was used as the electrolyte for the anode electrolysis chamber of the electrolytic cell, and a K2TaF7 (40% wt)-NaCl (40% wt)-KCl (20% wt) molten salt was used as the electrolyte for the cathode electrolysis chamber. The molten salt temperature in both the anode and cathode electrolysis chambers was controlled at 750℃, and the temperature of the liquid alloy at the bottom of the electrolytic cell was controlled at 1100℃. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt in the anode electrolysis chamber, and the tantalum cathode was inserted into the molten salt in the cathode electrolysis chamber. Tantalum pentoxide (85% wt) was added to the anode electrolysis chamber at 1.5% of the total mass of the molten salt in the anode electrolysis chamber. Electrolysis was performed for 12 hours, and the anode current density was controlled at 0.01 A / cm². 2 The cathode product, metallic tantalum, was obtained in the cathode electrolysis chamber (the purity of tantalum was tested to be 99.96%).

[0046] Example 3

[0047] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0048] (1) A tantalum-manganese alloy (20% wt tantalum, 80% wt manganese) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous flow rate of 25 mL / min is maintained to provide argon protection. The electrolytic cell is then heated to 1300℃ and held for 2 hours to completely melt the tantalum-manganese alloy in the electrolytic cell. The resulting liquid alloy divides the electrolytic cell into an anode electrolytic chamber and a cathode electrolytic chamber.

[0049] (2) A molten salt of (46.7 at%) NaCl-CaCl2 (53.3 at%) was used as the electrolyte in the anode electrolysis chamber of the electrolytic cell, and a molten salt of Na2TaF7 (40% wt)-NaCl (40% wt)-KCl (20% wt) was used as the electrolyte in the cathode electrolysis chamber. Tantalum pentoxide (85% wt purity) was added to the alloy interface in the anode electrolysis chamber. The temperatures in both the anode and cathode electrolysis chambers were then controlled at 750°C, and the temperature of the liquid alloy at the bottom of the electrolytic cell was controlled at 1300°C. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt in the anode electrolysis chamber, and the tantalum cathode was inserted into the molten salt in the cathode electrolysis chamber. Electrolysis was performed for 12 hours, with the anode current density controlled at 0.5 A / cm². 2 The cathode product, metallic tantalum, was obtained in the cathode electrolysis chamber (the purity of tantalum was tested to be 99.95%).

[0050] Example 4

[0051] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0052] (1) A tantalum-nickel alloy (30% wt tantalum, 70% wt nickel) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous flow rate of 30 mL / min is maintained to provide argon protection. The electrolytic cell is then heated to 1500℃ and held for 2 hours to allow the tantalum-nickel alloy in the electrolytic cell to completely melt. The resulting liquid alloy divides the electrolytic cell into an anode electrolytic chamber and a cathode electrolytic chamber.

[0053] (2) A Na₂TaF₇ (40% wt)-NaCl (40% wt)-KCl (20% wt) molten salt was used as the electrolyte for the anode electrolysis chamber of the electrolytic cell, and a K₂TaF₇ (17.5% wt)-KF (27.5% wt)-KCl (55.0% wt) molten salt was used as the electrolyte for the cathode electrolysis chamber. The molten salt temperature in both the anode and cathode electrolysis chambers was controlled at 700℃, and the temperature of the liquid alloy at the bottom of the electrolytic cell was controlled at 1500℃. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt of the anode electrolysis chamber, and the tungsten cathode was inserted into the molten salt of the cathode electrolysis chamber. Tantalum pentoxide (88% wt) was added to the anode electrolysis chamber at 2% of the total mass of the molten salt. Electrolysis was performed for 16 hours, with the anode current density controlled at 1.0 A / cm². 2 The cathode product, metallic tantalum, was obtained in the cathode electrolysis chamber (the purity of tantalum was tested to be 99.95%).

[0054] Example 5

[0055] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0056] (1) A tantalum-cobalt alloy (30% wt tantalum, 70% wt cobalt) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous flow rate of 10 mL / min is maintained to provide argon protection. The electrolytic cell is then heated to 1400℃ and held for 2 hours to allow the tantalum-cobalt alloy in the electrolytic cell to completely melt. The resulting liquid alloy divides the electrolytic cell into an anode electrolytic chamber and a cathode electrolytic chamber.

[0057] (2) A K2TaF7 (17.5% wt)-KF (27.5% wt)-KCl (55.0% wt) molten salt was used as the electrolyte for the anode electrolysis chamber of the electrolytic cell, and a K2TaF7 (40% wt)-NaCl (40% wt)-KCl (20% wt) molten salt was used as the electrolyte for the cathode electrolysis chamber. The molten salt temperature in both the anode and cathode electrolysis chambers was controlled at 750℃, and the temperature of the liquid alloy at the bottom of the electrolytic cell was controlled at 1400℃. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt of the anode electrolysis chamber, and the molybdenum cathode was inserted into the molten salt of the cathode electrolysis chamber. Tantalum pentoxide (98% wt) was added to the anode electrolysis chamber at 2% of the total mass of the molten salt. Electrolysis was performed for 20 hours, and the anode current density was controlled at 2.0 A / cm². 2 The cathode product, metallic tantalum, was obtained in the cathode electrolysis chamber (the purity of tantalum was tested to be 99.95%).

[0058] Example 6

[0059] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0060] (1) A tantalum-iron alloy (20% wt tantalum, 80% wt iron) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous argon gas supply is maintained at a flow rate of 10 mL / min. The electrolytic cell is then heated to 1500℃ and held at that temperature for 1.5 hours to allow the tantalum-iron alloy in the electrolytic cell to completely melt. The resulting liquid alloy divides the electrolytic cell into an anode electrolytic chamber and a cathode electrolytic chamber.

[0061] (2) A CaCl2 (95% wt)-CaO (5% wt) molten salt was used as the electrolyte for the anode electrolysis chamber of the electrolytic cell, and a K2TaF7 (40% wt)-NaCl (40% wt)-KCl (20% wt) molten salt was used as the electrolyte for the cathode electrolysis chamber. Tantalum pentoxide (92% wt purity) was added to the alloy interface of the anode electrolysis chamber. The molten salt temperature in both the anode and cathode electrolysis chambers was controlled at 800℃, and the liquid alloy temperature at the bottom of the electrolytic cell was controlled at 1500℃. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt of the anode electrolysis chamber, and the tantalum cathode was inserted into the molten salt of the cathode electrolysis chamber. Electrolysis was performed for 20 hours, with the anode current density controlled at 1.2 A / cm². 2 The cathode product, metallic tantalum, was obtained in the cathode electrolysis chamber (the purity of tantalum was tested to be 99.96%).

[0062] Example 7

[0063] This embodiment provides a method for preparing tantalum metal by molten salt electrolysis, including the following steps:

[0064] (1) A tantalum-platinum alloy (50%wt tantalum, 50%wt platinum) is placed at the bottom of the electrolytic cell beforehand. The electrolytic cell is evacuated and then inert argon gas is introduced. After the argon gas is filled, a continuous argon gas supply is maintained at a flow rate of 50 mL / min. The electrolytic cell is then heated to 1800℃ and held for 2 hours to completely melt the tantalum-platinum alloy in the electrolytic cell. The resulting liquid alloy divides the electrolytic cell into an anode electrolytic chamber and a cathode electrolytic chamber.

[0065] (2) A K2TaF7 (17.5% wt)-KF (27.5% wt)-KCl (55.0% wt) molten salt was used as the electrolyte for the anode electrolysis chamber of the electrolytic cell, and a K2TaF7 (40% wt)-NaCl (40% wt)-KCl (20% wt) molten salt was used as the electrolyte for the cathode electrolysis chamber. The molten salt temperature in both the anode and cathode electrolysis chambers was controlled at 750℃, and the temperature of the liquid alloy at the bottom of the electrolytic cell was controlled at 1800℃. After the temperatures of each section of the electrolytic cell stabilized, the graphite anode was inserted into the molten salt in the anode electrolysis chamber, and the tantalum cathode was inserted into the molten salt in the cathode electrolysis chamber. Tantalum pentoxide (purity 98% wt) was added to the anode electrolysis chamber at 1.8% of the total mass of the molten salt in the anode electrolysis chamber. Electrolysis was performed for 24 hours, and the anode current density was controlled at 0.8 A / cm². 2 The cathode product, metallic tantalum, was obtained in the cathode electrolysis chamber (the purity of tantalum was tested to be 99.98%).

[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing tantalum metal by molten salt electrolysis, characterized in that, Includes the following steps: (1) Take an electrolytic cell containing an anode electrolytic chamber and a cathode electrolytic chamber, and place liquid tantalum alloy at the bottom of the electrolytic cell to separate the anode electrolytic chamber and the cathode electrolytic chamber. The anode and cathode are respectively placed in the anode electrolytic chamber and the cathode electrolytic chamber. (2) Add molten salt a to the anode electrolysis chamber and molten salt b to the cathode electrolysis chamber; (3) Add the raw material tantalum pentoxide to the anode electrolysis chamber, turn on the power and generate solid tantalum metal at the cathode; Wherein: the molten salt a is composed of one or more of calcium chloride, barium chloride, strontium chloride, lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, and lanthanum chloride; or, the molten salt a is composed of one of potassium fluorotantalate and sodium fluorotantalate, together with one or more of potassium chloride, potassium fluoride, sodium chloride, sodium fluoride, lithium chloride, lithium fluoride, calcium chloride, and calcium fluoride; The molten salt b is composed of one of potassium fluorotantalate and sodium fluorotantalate, and one or more of sodium chloride, potassium chloride, lithium chloride, calcium chloride, barium chloride, lithium fluoride, sodium fluoride, and potassium fluoride. The liquid alloy is composed of tantalum and one of the following: gold, platinum, nickel, iron, cobalt, and manganese. The operating temperature of the electrolytic cell is 700~1800℃ o C.

2. The method for preparing tantalum metal by molten salt electrolysis according to claim 1, characterized in that, In step (1), the anode is a graphite anode.

3. The method for preparing tantalum metal by molten salt electrolysis according to claim 1, characterized in that, In step (1), the cathode is a tantalum cathode, a tungsten cathode, or a molybdenum cathode.

4. The method for preparing metallic tantalum by molten salt electrolysis according to claim 1, characterized in that, In step (3), the purity of tantalum pentoxide is ≥80%wt.

5. The method for preparing tantalum metal by molten salt electrolysis according to claim 1, characterized in that, In step (3), the anolyte current density during electrolysis is 0.01~2.0 A / cm². 2 .

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