A device for preparing high-purity titanium by electrolysis of titanium dioxide

Abstract

The application relates to a device for preparing high-purity titanium by electrolyzing titanium dioxide, and belongs to the technical field of molten salt electrochemical metallurgy. The device divides an electrolytic cell into three isolated chambers, i.e. a preparation cell, an anode chamber and a cathode chamber. TiO2 is fully dissolved in the preparation cell to obtain high-content high-valence titanium (Ti 4+ ), which further undergoes a centralization reaction with zero-valence titanium (Ti 0 ) in the preparation cell in advance to generate low-valence ions (Ti n+ , 2<=n<=2.5, n is an average valence) which are easy to reduce. The TiO2 in the preparation cell can be subjected to the above pretreatment process (centralization reaction) to ensure that the titanium in the molten salt entering the anode chamber mainly exists in a low valence state, thereby avoiding a series of disproportionation reactions and mutual conversion among titanium ions of various valences caused by directly adding TiO2 into the anode chamber, reducing the side reaction current efficiency, and improving the current efficiency.

Description

Technical Field

[0001] This invention relates to the field of molten salt electrochemical metallurgy, and in particular to an apparatus for preparing high-purity titanium by electrolysis of titanium dioxide. Background Technology

[0002] Titanium is lightweight, high-strength, and has excellent corrosion resistance, making it a key material in many fields, including artificial satellites, space shuttles, underwater submarines, and marine equipment. Currently, the industrial production of titanium still uses the thermal reduction process of titanium magnesium tetrachloride (also known as the Kroll process), invented by Luxembourg scientist Kroll in 1940. This process is cumbersome, has high raw material costs, high energy consumption and carbon emission intensity (approximately 25 t CO2e / t-Ti), is labor-intensive, and is intermittent, thus severely limiting the large-scale application of titanium.

[0003] For the past 80 years, people have been seeking electrolytic titanium refining methods, but industrialization has yet to be achieved. In existing technologies, the anode, cathode, and electrolyte of the electrolytic cell are all located in the same chamber: firstly, impurity ions (such as Cu, Fe, Si, etc.) introduced by the corrosion of raw materials and electrodes will inevitably be preferentially reduced into the titanium product due to the correction of electrode potential; secondly, Ti has a strong affinity for dissolved oxygen in molten salt, making deoxidation difficult and making it hard to obtain high-quality metallic titanium.

[0004] To address this, Chinese Patent 202110499895.8 discloses a method for producing metallic aluminum by molten salt electrolysis of alumina. This method uses a bottom liquid alloy to connect the cathode and anode chambers, leveraging its excellent impurity removal capabilities to directly electrolyze 99.99% high-purity aluminum from Al2O3 using an inert anode, and constructs a kiloampere-level electrolysis system. Further application to TiO2 electrolysis utilizes a liquid alloy mediator layer to allow TiO2 to dissolve immediately after reduction into the alloy, while simultaneously oxidizing at the cathode chamber alloy interface and entering the cathode molten salt. This effectively blocks dissolved oxygen in the anode chamber and traps inert metallic impurities in the bottom alloy, creating conditions for the preparation of high-purity titanium. US Patent 2,861,030 also employs a similar liquid alloy dual-chamber electrolysis method for titanium. However, the above methods have the following technical problems in practical applications: (1) The US2861030A uses two independent DC power supplies connected to the "anode" respectively. "Liquid alloy" and "liquid alloy" The "cathode" attempts to maintain dynamic balance by independently adjusting the current on both sides. However, at industrial scale (thousands to tens of thousands of amperes), the shared liquid electrode leads to strong coupling of the electric, thermal, and magnetic fields of the two circuits. Independent adjustment, on the contrary, causes uneven current distribution, mutual disturbance of temperature fields, and unstable electromagnetic stirring, exacerbating system instability and imbalance. In addition, the dual-power supply system requires two sets of rectifier power supplies, a complex control system, and additional busbars and contact resistance. According to the cell voltage distribution of large electrolytic cells (Nature, 606(7914), 511-515), the cell voltage is 0.8V higher than that of the electrolytic cell invented in Chinese Patent 202110499895.8, and the power consumption increases by about 2000kWh / ton Ti. This is seriously contrary to the current direction of energy saving and consumption reduction in large electrolytic cells. (2) The selection of the lining material of the molten salt electrolytic cell is crucial to its large-scale stable operation and service life. US2861030A uses a graphite cavity to hold liquid titanium alloy, but the titanium-containing melt is very easy to react with carbon at >900℃ to form high-melting-point titanium carbide (TiC, melting point 3140℃) (Li Honggui, Rare Metal Metallurgy, Metallurgical Industry Press, 2008: 106), which causes the liquid alloy to gradually become viscous, the interface to deteriorate, and even the electrolytic cell to fail to operate normally.

[0005] (3) Titanium, as a typical transition metal, has multivalent ions (Ti... 4+ Ti 3+ Ti 2+ There are serious disproportionation and transformation reactions between them (Journal of the Electrochemical Society, 164(9), D551; Metallurgical and Materials Transactions B, 44(4), 906-913). According to Chinese Patent 202110499895.8, the aluminum electrolysis operation is directly applied to titanium electrolysis, and TiO2 is added to the anode chamber to make Ti 4+ Reduced to Ti at the anolyte-liquid alloy interface 0 Ti is placed at the alloy interface of the cathode chamber. 0 Oxidation to Ti 2+As electrolysis proceeds, the titanium content in the bottom liquid alloy inevitably becomes severely unbalanced. US2861030A attempts to maintain titanium balance by setting the anode current density to twice that of the cathode (the example mentions that when using TiO2, the anode chamber current is manually adjusted to 150 A, and the cathode chamber independent current is 75 A). However, existing research shows that this method cannot compensate for the current loss caused by multivalent state disproportionation. When using liquid Fe, Sb, and Sn electrodes to electrolyze TiO2 at Beijing University of Science and Technology, the current efficiencies were only 69%, 17-64%, and 10%, respectively (Doctoral dissertation: Fundamental Research on Electrolytic Preparation of Titanium and its Alloys from Molten Titanium-Containing Blast Furnace Slag, 2022; Electrode Process of Titanium Ions on Liquid Metal Cathode, 2018); previous studies have also confirmed that the current efficiency is below 10.4% when using liquid copper electrodes. It can be seen that even under precise control conditions in the laboratory, the current efficiency of the anode chamber is generally below 70%, and in some systems even below 10%. This is one of the key reasons why titanium electrolysis has not achieved an industrial breakthrough in more than eighty years. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide an apparatus for preparing high-purity titanium by electrolysis of titanium dioxide, in order to solve at least one of the following problems in existing electrolysis apparatus: low current efficiency due to disproportionation reaction between multivalent titanium ions, making it difficult to meet the needs of large-scale production; difficulty in controlling the electrolysis process; easy excess of carbon, oxygen and metal impurities in the product; insufficient process continuity and stability, making it difficult to achieve continuous titanium production.

[0007] The first method, the present invention provides an apparatus for preparing high-purity titanium by electrolysis of titanium dioxide, the apparatus including an electrolytic cell, the inner cavity of the electrolytic cell being divided into a preparation tank, an anode chamber and a cathode chamber in a transverse direction by a first partition and a second partition; The first partition is provided with an upper one-way valve and a lower one-way valve in opposite directions from top to bottom, so as to realize the directional flow of molten salt between the preparatory tank and the anode chamber; A communication port is provided between the lower end of the second partition and the bottom surface of the electrolytic cell. The communication port is filled with a liquid alloy layer to form a liquid seal. The lower end of the second partition is immersed in the liquid alloy layer to physically isolate the molten salt between the anode chamber and the cathode chamber. The top surfaces of the preparatory tank, anode chamber, and cathode chamber are respectively provided with independent controllable gas outlets and gas inlets.

[0008] Furthermore, the upper end of the first partition is sealed to the top surface of the electrolytic cell, the lower end of the first partition is sealed to the bottom surface of the electrolytic cell, and the upper end of the second partition is sealed to the top surface of the electrolytic cell.

[0009] Furthermore, the liquid alloy layer also fills the bottom of the anode chamber and the bottom of the cathode chamber.

[0010] Furthermore, the preparation tank also includes a porous material placement cavity surrounded by a porous plate, the upper end of which is sealed to the top surface of the electrolytic cell, and the lower end of which is sealed to the bottom surface of the electrolytic cell.

[0011] Furthermore, the top surface of the porous material storage cavity is provided with a pre-filled groove.

[0012] Furthermore, the lower one-way valve is higher than the upper surface of the liquid alloy layer, and the lower one-way valve only allows molten salt from the preparation tank to flow into the anode chamber. The upper one-way valve is higher than the height of the molten salt in the anode chamber, and the upper one-way valve only allows molten salt from the anode chamber to flow into the preparation tank.

[0013] Furthermore, the electrolytic cell comprises, from the outside in, a stainless steel shell, a heat insulation layer, a thermal insulation layer, and a graphite tank body connected in sequence.

[0014] Furthermore, an anode is provided in the anode chamber, with the lower end of the anode immersed in anode molten salt, and a cathode is provided in the cathode chamber, with the lower end of the cathode immersed in cathode molten salt.

[0015] Furthermore, a sealed dual-chamber cathode cooling chamber is provided above the cathode chamber. The dual-chamber cathode cooling chamber includes a first cathode cooling chamber and a second cathode cooling chamber, and the first cathode cooling chamber and the second cathode cooling chamber share a cooling chamber partition.

[0016] Secondly, the present invention provides a method for preparing high-purity titanium by electrolyzing titanium dioxide based on the above-mentioned apparatus.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The apparatus of the present invention divides the electrolytic cell into three isolated chambers: a preparatory chamber, an anode chamber, and a cathode chamber. TiO2 is fully dissolved in the preparatory chamber to obtain a high content of high-valence titanium (TiO2). 4+ ), which is further related to zero-valent titanium (Ti 0 A disproportionation reaction occurs beforehand in the preparative tank, generating easily reducible low-valence ions (Ti). n+ (2≤n≤2.5, where n is the average valence state). The pretreatment process (disproportionation reaction) of TiO2 in the pretreatment tank ensures that the titanium in the molten salt entering the anode chamber is mainly in a low valence state. This avoids the series of disproportionation reactions and interconversions between titanium ions of different valence states caused by directly adding TiO2 to the anode chamber, reducing current wastage due to side reactions and improving current efficiency. Furthermore, by using a one-way valve, the low-valence Ti-rich... n+ Molten salt from the preparatory tank is unidirectionally forced into the anode chamber to replenish the titanium source; the Ti in the anode chamber, which was degraded by electrolysis, is discharged through the upper one-way valve. n+The reduced-concentration "titanium-poor molten salt" is unidirectionally returned to the preparation tank to dissolve new TiO2 and prepare high-concentration Ti again. n+ Molten salt. This closed-loop cycle ensures that a high concentration of low-valent Ti is maintained in the anode chamber. n+ This simultaneously enables the recycling of molten salt and continuous electrolysis. The connection port below the second partition is filled with a liquid alloy layer shared by the anode and cathode chambers, achieving physical isolation between the anode and cathode molten salts, but allowing the alloy layer to conduct electrons and transfer titanium atoms.

[0018] 2. This invention avoids current waste caused by the dissolution and neutralization reaction of TiO2 in the pre-treatment tank, thus achieving a stable current efficiency of over 80%. It uses only a single power supply, eliminating the need for a complex dual-loop control system, meeting the energy-saving and consumption-reducing requirements of large-scale electrolytic cells. Simultaneously, the liquid alloy layer enables in-situ separation of impurities, preventing them from entering the final titanium product and directly yielding high-purity metallic titanium. Furthermore, the entire process can be controlled by differential pressure to achieve closed-loop molten salt circulation, enabling continuous and stable electrolytic production. Compared to the multiple processes required by the Kroll method, such as chlorination, distillation, magnesium reduction, and vacuum distillation, the process flow is significantly shortened, overcoming the technical limitations of existing molten salt electrolysis schemes in terms of continuity and long-term stability. This provides a feasible technical solution for the industrial production of titanium electrolysis.

[0019] 3. The liquid alloy in the device of this invention reduces the stringent requirements for the purity of TiO2 raw materials by intercepting impurities, eliminating the need for TiCl4 preparation and purification in the Kroll method, and significantly reducing raw material costs. Simultaneously, the liquid alloy layer isolates dissolved oxygen in the anode chamber from contact with the cathode titanium product. The product oxygen content is ≤0.11%, and the total metallic impurity content is ≤0.1%. Production costs are reduced by approximately 52% compared to the Kroll method (based on comprehensive energy consumption per ton of titanium). When using an inert anode, there is no CO2 emission from the anode reaction, and the direct process carbon emissions are zero (excluding indirect emissions from electricity), while the Kroll method emits approximately 25 tons of CO2 per ton of titanium. 2e .

[0020] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0021] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0022] Figure 1 This is a schematic diagram of the structure of an apparatus for preparing high-purity titanium by electrolysis of titanium dioxide according to the present invention; Figure 2 An optical photograph of metallic titanium generated by electrolysis in Example 2 of this invention; Figure 3 The image shows the XRD pattern of metallic titanium generated by electrolysis in Example 2 of this invention.

[0023] Figure label: 1-Stainless steel shell, 2-Insulation layer, 3-Heat insulation layer, 4-Graphite tank, 5-First partition, 6-Second partition, 7-Preparation tank, 8-Anode chamber, 9-Cathode chamber, 10-Upper check valve, 11-Lower check valve, 12-Liquid alloy layer, 13-Gas inlet, 14-Gas outlet, 15-Perforated plate, 16-Preparation tank feed port, 17-Anode, 18-First cathode, 19-Cathode feed port, 20-First cathode cooling chamber, 201-First cathode conductive rod, 21-Second cathode cooling chamber, 211-Second cathode conductive rod, 212-Second cathode, 22-Cooling chamber partition, 23-Inflation port, 24-Extraction port, 25-Vacuum valve, 26-Preparation tank discharge port, 27-Cathode chamber discharge port. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0025] A specific embodiment of the present invention, such as Figure 1 As shown, an apparatus for preparing high-purity titanium by electrolysis of titanium dioxide is disclosed. The apparatus includes an electrolytic cell, the inner cavity of which is divided into a preparatory tank 7, an anode chamber 8 and a cathode chamber 9 in a transverse direction by a first partition 5 and a second partition 6. The first partition is provided with an upper one-way valve 10 and a lower one-way valve 11 in opposite directions from top to bottom, so as to realize the directional flow of molten salt between the preparatory tank 7 and the anode chamber 8; A communication port is provided between the lower end of the second partition 6 and the bottom surface of the electrolytic cell. The communication port is filled with a liquid alloy layer 12 and forms a liquid seal. The lower end of the second partition 6 is immersed in the liquid alloy layer 12 so as to physically isolate the molten salt between the anode chamber 8 and the cathode chamber 9. The top surfaces of the preparatory tank 7, anode chamber 8, and cathode chamber 9 are respectively provided with independent controllable gas outlets 14 and gas inlets 13.

[0026] Compared with the prior art, the device of the present invention divides the electrolytic cell into three isolated chambers: a preparatory tank 7, an anode chamber 8, and a cathode chamber 9. TiO2 is fully dissolved in the preparatory tank 7 to obtain a high content of high-valence titanium (TiO2).4+ ), which is further related to zero-valent titanium (Ti 0 A disproportionation reaction occurs beforehand in preparatory tank 7, generating easily reducible low-valence ions (Ti). n+ 2≤n≤2.5, where n is the average valence state, for example, 2, 2.1, 2.2, 2.3, 2.4, 2.5). The pretreatment process (disproportionation reaction) of TiO2 in the pretreatment tank 7 ensures that the titanium in the molten salt entering the anode chamber 8 is mainly in a low valence state. This avoids the series of disproportionation reactions and interconversions between titanium ions of different valence states caused by directly adding TiO2 to the anode chamber 8, reducing current wastage due to side reactions and improving current efficiency. Furthermore, the low-valence Ti-rich TiO2 is introduced into the anode chamber 8 via the one-way valve 11. n+ Molten salt in the preparatory tank 7 is unidirectionally pressed into the anode chamber 8 to replenish the titanium source; the Ti in the anode chamber 8 due to electrolysis is discharged through the upper one-way valve 10. n+ The reduced-concentration "titanium-poor molten salt" is unidirectionally returned to the preparation tank 7 to dissolve new TiO2 and prepare high-concentration Ti again. n+ Molten salt. This closed-loop circulation ensures that a high concentration of low-valent Ti is maintained within anode chamber 8. n+ This simultaneously enables the recycling of molten salt and continuous electrolysis. The connection port below the second partition 6 is filled with a liquid alloy layer 12 shared by the anode chamber 8 and the cathode chamber 9, achieving physical isolation between the anode molten salt and the cathode molten salt, but allowing the alloy layer to conduct electrons and transfer titanium atoms.

[0027] It should be noted that the average valence state in this invention is the weighted average valence state of titanium ions with different valence states in the molten salt. Specifically, divalent titanium is determined by hydrogenometry, trivalent titanium is determined by ferric ammonium persulfate titration, and tetravalent titanium is determined by hydrogen peroxide spectrophotometry. Those skilled in the art can understand its specific meaning based on this definition.

[0028] Specifically, the upper end of the first partition is sealed to the top surface of the electrolytic cell, the lower end of the first partition is sealed to the bottom surface of the electrolytic cell, and the upper end of the second partition 6 is sealed to the top surface of the electrolytic cell.

[0029] Specifically, the liquid alloy layer 12 also fills the bottom of the anode chamber 8 and the bottom of the cathode chamber 9.

[0030] It should be noted that the liquid alloy layer fills the bottom of the anode chamber 8 and the cathode chamber 9, and the connecting port is filled by the liquid alloy layer 12 shared by the anode chamber 8 and the cathode chamber 9, achieving physical isolation between the anode molten salt and the cathode molten salt, but allowing the liquid alloy layer to conduct electrons and transfer titanium atoms. Under DC power supply, the interface of the liquid alloy layer 12 is in an induced polarization state, and it is stable at the Ti at the interfaces with the cathode and anode molten salts, respectively. 0 / Ti n+ Near the equilibrium potential, but in the opposite direction: Ti occurs on the anode 17 side.n+ (Anode molten salt) + ne - → Ti (alloy), Ti (alloy) occurs on the cathode side → Ti n+ (Cathode molten salt) + ne - This allows the liquid alloy to function solely as a medium for transporting electrons and titanium atoms, while its composition remains essentially unchanged.

[0031] Preferably, the liquid alloy layer 12 contains a base metal Ti and a composite additive metal, wherein the composite additive metal includes one or more of Cu, Sn, Sb, Bi, Ni, and Ag. Specifically, the preparation tank 7 also includes a porous material placement cavity surrounded by a porous plate 15. The upper end of the porous plate 15 is sealed to the top surface of the electrolytic cell, and the lower end of the porous plate 15 is sealed to the bottom surface of the electrolytic cell.

[0032] Preferably, the top surface of the porous material storage chamber is provided with a pre-filled groove inlet 16. The inlet is used to add titanium dioxide and metallic titanium into the porous material storage chamber, where they react with the molten salt (with the same electrolyte composition as the anode chamber 8) within the chamber. This causes the tetravalent titanium ions generated from the dissolution of titanium dioxide to react with the metal, generating low-valent titanium ions (Ti). n+ , where 2≤n≤2.5, flows out of the porous material chamber through multiple through holes on the porous plate 15.

[0033] Specifically, the lower one-way valve 11 is higher than the upper surface of the liquid alloy layer 12, and the lower one-way valve 11 only allows the molten salt of the preparation tank 7 to flow into the anode chamber 8. The upper one-way valve 10 is higher than the height of the molten salt in the anode chamber 8, and the upper one-way valve 10 only allows the molten salt of the anode chamber 8 to flow into the preparation tank 7.

[0034] Specifically, the electrolytic cell comprises, from the outside to the inside, a stainless steel shell 1, a heat insulation layer 2, a heat preservation layer 3, and a graphite tank 4 connected in sequence.

[0035] Specifically, an anode 17 is provided in the anode chamber 8, and the lower end of the anode 17 is immersed in the anode molten salt. A cathode is provided in the cathode chamber 9, and the lower end of the cathode is immersed in the cathode molten salt.

[0036] Preferably, the top surface of the cathode chamber 9 is provided with a cathode feed port 19, the lower end of the cathode chamber 9 is provided with a cathode discharge port 27, and the lower end of the preparation tank 7 is provided with a preparation tank discharge port 26.

[0037] It should be noted that all components in contact with molten salt in this invention are provided with an inner protective lining layer. For example, the parts of the graphite tank 4 that contact molten salt, the parts of the first partition 5 and the second partition 6 that contact molten salt, and the parts of the porous plate 15 that contact molten salt are all provided with an inner protective lining layer. The inner protective lining layer is made of insulating, high-temperature resistant, and corrosion-resistant materials, such as yttrium oxide, boron nitride, zirconium oxide, and silicon nitride.

[0038] In the device of the present invention, the graphite tank 4 does not directly contact the titanium-containing liquid alloy, but only serves as a structural support for the electrolytic cell. The liquid alloy layer 12 only directly contacts the bottom of the second partition, the bottom of the electrolytic cell, and the dense inner lining protective layer with stronger corrosion resistance. This avoids the problem of titanium reacting with carbon at high temperature to form titanium carbide, which causes the liquid alloy to become viscous and the interface to deteriorate. This effectively extends the service life of the electrolytic cell and ensures the long-term stable operation of the electrolysis process.

[0039] Preferably, a sealed dual-chamber cathode cooling chamber is provided above the cathode chamber 9. The dual-chamber cathode cooling chamber includes a first cathode cooling chamber 20 and a second cathode cooling chamber 21, and the first cathode cooling chamber 20 and the second cathode cooling chamber 21 share a cooling chamber partition 22. Preferably, the cathode includes a first cathode 18 and a second cathode 212 connected in parallel.

[0040] A first cathode conductive rod 201 is provided in the first cathode cooling chamber 20. The upper end of the first cathode conductive rod 201 is connected to the negative terminal of the DC power supply, and the lower end of the first cathode conductive rod 201 is connected to the first cathode 18. The second cathode cooling chamber 21 is provided with a second cathode conductive rod 211, which is connected to the negative terminal of the DC power supply. The lower end of the second cathode conductive rod 211 is connected to a second cathode 212. The second cathode conductive rod 211 is a telescopic structure. The first cathode conductive rod 201 and the second cathode conductive rod 211 are connected in parallel.

[0041] It should be noted that the dual-chamber cooling chamber allows for alternating insertion of cathodes. For example, after the first cathode 18 has produced a significant amount of product through electrolysis, it can be raised to the cooling chamber, the vacuum valve 25 closed, a vacuum evacuated, and inert gas introduced before further cooling. Simultaneously, the second cathode 212 is lowered for continuous electrolysis. After the first cathode 18 cools to a certain temperature, it is removed, the cathode product is taken out, and then the first cathode 18 is placed back into the cooling chamber, where a vacuum is evacuated and inert gas is introduced for later use. The dual-chamber cooling chamber enables continuous electrolysis and prevents the cathode from being oxidized by oxygen in the air when it is removed at high temperatures, thus preventing excessive oxygen content. The cooling chamber is relatively high, and the temperature within it is only 100-200℃. Water-cooled pipes can be laid around the chamber for further cooling.

[0042] More preferably, the first cathode cooling chamber 20 and the second cathode cooling chamber 21 are each provided with an air inlet 23, an air extraction port 24 and a vacuum valve 25.

[0043] It should be noted that the top surfaces of the preparatory tank 7, anode chamber 8, and cathode chamber 9 of the present invention are respectively provided with independently controllable gas outlets 14 and gas inlets 13. By controlling the gas pressure in the preparatory tank 7, anode chamber 8, and cathode chamber 9, the regeneration and recovery of molten salt are achieved using the pressure difference. The device of the present invention prevents more reactive metallic impurities (such as aluminum and magnesium) from being reduced at the liquid alloy interface on the anode side and thus from entering the liquid alloy layer 12. Even if less reactive impurities (such as copper and iron) are reduced along with titanium and enter the liquid alloy layer 12, they cannot be oxidized into ions because their electrode potential is more positive than that of titanium, and are therefore blocked in the liquid alloy layer 12, thereby achieving efficient separation of impurities. The anode chamber 8 and cathode chamber 9 are separated to avoid contact between dissolved oxygen in the molten salt and the cathode titanium product, ensuring the production of low-oxygen titanium.

[0044] The preparatory tank 7 of this invention dissolves TiO2 and provides a stable low-valent titanium molten salt. The upper one-way valve 10 and the lower one-way valve 11 realize the regeneration and reuse of molten salt through air pressure control, maintaining the continuous dissolution of TiO2 and the low-valent titanium concentration in the anode chamber 8. The dual interface and adaptive regulation of the liquid alloy layer 12 enable the simultaneous completion of titanium transfer and impurity separation. The various structures of the device of this invention cooperate with each other to form an integrated system of "TiO2 dissolution and pretreatment → directional transport → in-situ impurity isolation", ultimately achieving high current efficiency, continuous, low cost, low energy consumption, and high-purity titanium preparation.

[0045] Another specific embodiment of the present invention discloses a method for preparing high-purity titanium by electrolyzing titanium dioxide using the above-described apparatus, comprising the following steps: (a) Add titanium dioxide, metallic titanium and anolyte to the preparative tank 7, add anolyte to the anode chamber 8, add cathode electrolyte to the cathode chamber 9, and add liquid alloy to the anode and cathode chambers. Connect the positive and negative terminals of the external DC power supply to the anode 17 and the cathode respectively to carry out the electrolysis reaction. (b) At the operating temperature, titanium dioxide and metallic titanium dissolve in the anolyte of the preparative tank 7. Tetravalent titanium ions react with zero-valent titanium ions in the preparative tank 7 to generate Ti containing low-valent titanium ions. n+ molten salts, where 2 ≤ n ≤ 2.5; (c) By controlling the pressure difference between the preparatory tank 7 and the anode chamber 8, the low-valence titanium ions Ti are produced. n+ The molten salt circulates in a directional closed loop between the preparatory tank 7 and the anode chamber 8 through the upper one-way valve 10 and the lower one-way valve 11; (d) During the electrolysis process, low-valence titanium ions Ti in the anode chamber 8 n+At the interface of the liquid alloy layer 12, the titanium atoms are reduced to titanium atoms and enter the liquid alloy layer 12. At the interface of the liquid alloy layer 12 in the cathode chamber 9, the titanium atoms are oxidized to low-valence titanium ions (Ti). n+ Low-valence titanium ions (Ti) enter the cathode molten salt. n+ High-purity titanium is generated by reduction precipitation on the cathode.

[0046] Compared with existing technologies, the method of this invention avoids the current waste caused by the dissolution and neutralization reaction of TiO2 in the preparative tank 7, and the current efficiency can be stably increased to over 80%. It only uses a single power supply and does not require a complex dual-loop control system, which meets the development requirements of energy saving and consumption reduction in large electrolytic cells. At the same time, the liquid alloy layer 12 realizes the in-situ isolation and separation of impurities, preventing impurities from entering the final titanium product, and high-purity metallic titanium can be obtained directly. In addition, the entire process can achieve closed-loop circulation of molten salt by controlling the gas pressure difference, which can carry out continuous and stable electrolytic production. Compared with the multiple processes such as chlorination, distillation, magnesium reduction, and vacuum distillation required by the Kroll method, the process flow is significantly shortened, which breaks through the technical limitations of existing molten salt electrolysis schemes in terms of continuity and long-term stability, and provides a feasible technical solution for the industrial production of titanium electrolysis.

[0047] Specifically, in step (a), the mass ratio of titanium dioxide to anode electrolyte in the preparative tank 7 is 0.05~0.3 (0.05, 0.07, 0.09, 0.11, 0.13, 0.15, 0.17, 0.19, 0.21, 0.23, 0.25, 0.27, 0.29, 0.3), and the mass ratio of titanium dioxide to titanium in metallic titanium is 1~2.5 (e.g., 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.5).

[0048] Preferably, the titanium metal is titanium alloy waste or sponge titanium.

[0049] Specifically, in step (b), the operating temperature is 800~1100℃, for example, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, 1020℃, 1040℃, 1060℃, 1080℃, 1100℃.

[0050] Specifically, in step (c), at the start of the reaction, the one-way valve 11 is opened using the pressure difference to release the low-valence titanium ions (Ti) from the preparatory tank 7. n+ Molten salt flows into anode chamber 8 until the molten salt level in anode chamber 8 reaches a predetermined height, then the lower check valve 11 is closed; Monitor the concentration of titanium ions in the molten salt in the anode chamber 8. If the concentration of titanium ions is ≤0.2%, open the upper one-way valve 10 using the air pressure difference to allow the molten salt in the anode chamber 8 that is higher than the upper one-way valve 10 to flow into the preparation tank 7.

[0051] Preferably, the predetermined height is 35% or more of the anode chamber height. More preferably, the predetermined height is 35-70% of the anode chamber height, for example, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%.

[0052] Specifically, in step (a), the current density of the anode 17 is 0.4~1.5 A·cm. -2 For example, 0.4 A·cm -2 0.5A·cm -2 0.6A·cm -2 0.7A·cm -2 0.8A·cm -2 0.9A·cm -2 1.0A·cm -2 1.1A·cm -2 1.2A·cm -2 1.3A·cm -2 1.4A·cm -2 1.5A·cm -2 The current density of the cathode is 0.4~1.5 A·cm. -2 For example, 0.4 A·cm -2 0.5A·cm -2 0.6A·cm -2 0.7A·cm -2 0.8A·cm -2 0.9A·cm -2 1.0A·cm -2 1.1A·cm -2 1.2A·cm -2 1.3A·cm -2 1.4A·cm -2 1.5A·cm -2 .

[0053] It should be noted that when the current efficiency is too high, the concentration polarization is enhanced, the stability of the magnetohydrodynamic fluid is reduced, and the cathode life is affected. The Joule heating generated when the current is too high will cause the electrolyte to overheat, and the copper in the bottom alloy is easily oxidized, resulting in a significant decrease in product purity. When the current density is too low, the capacity of a single cell will decrease, the fixed cost will increase, and the reaction will be uneven due to the low local current density. When the scale is large, the electrolysis temperature will also decrease due to insufficient Joule heating, resulting in increased melt viscosity and decreased current efficiency. The selection of current density is based on a comprehensive consideration of capacity, power consumption, electrolytic cell life and current efficiency.

[0054] Specifically, in step (a), the anode is graphite, copper-titanium alloy or inert anode, and the cathode is titanium, stainless steel, molybdenum, tungsten or metallic nickel; Specifically, in step (a), the anolyte in the anode chamber 8 is selected from one or more of NaF, KF, LiF, K2TiF6, and Na2TiF6, or a fluorine-chlorine mixed system composed of one or more of NaCl, KCl, LiCl, BaCl2, CsCl, MgCl2, and CaCl2 and one or more of NaF, KF, LiF, K2TiF6, and Na2TiF6; The cathode electrolyte in cathode chamber 9 is selected from one or more of NaCl, KCl, LiCl, BaCl2, CsCl, MgCl2, and CaCl2.

[0055] Preferably, low-valence titanium is also added to the cathode chamber 9. The average valence of the low-valence titanium is greater than 2.0 and less than 2.5, for example, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5. The mass of the low-valence titanium is 1 to 15% of the mass of the cathode electrolyte, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%.

[0056] Because high-valence titanium undergoes complex disproportionation and non-disproportionation reactions, which can significantly reduce current efficiency, it is necessary to add titanium salts of low-valence titanium to ensure current efficiency.

[0057] Specifically, in step (d), the ratio of the interface area of ​​the liquid alloy layer 12 to the cathode reaction surface area is β, where 2≤β≤5, for example, 2, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.

[0058] It should be noted that the interface area of ​​the liquid alloy layer 12 refers to the area of ​​the contact region between the liquid alloy layer 12 and the molten salt of the cathode chamber 9; the cathode reaction surface area refers to the effective surface area of ​​the cathode immersed in the cathode molten salt and in contact with the cathode molten salt to undergo a reduction reaction. This invention selects a specific range of liquid alloy interface area to cathode reaction area ratio β (2≤β≤5), which allows for stable oxidation at the liquid alloy interface of the cathode chamber 9 to produce Ti under a relatively high cathode current density. n+ (2≤n≤2.5) ensures that titanium in the cathode molten salt remains predominantly in a low-valence state, further suppressing the disproportionation reaction of high-valence titanium. The stable control of low-valence titanium in the anode chamber 8 and cathode chamber 9 guarantees high current efficiency in the electrolysis process. The method of this invention synergistically suppresses the disproportionation and shuttle effect between multivalent titanium ions at the source, improving current efficiency by 20%~40% compared to conventional titanium electrolysis processes.

[0059] The liquid alloy of this invention reduces the stringent requirements for TiO2 raw material purity by intercepting impurities, eliminating the need for TiCl4 preparation and refining in the Kroll process, thus significantly reducing raw material costs. Simultaneously, the liquid alloy layer 12 isolates dissolved oxygen in the anode chamber 8 from contact with the cathode titanium product. The product oxygen content is ≤0.11%, and the total metallic impurity content is ≤0.1%. Production costs are reduced by approximately 52% compared to the Kroll process (based on comprehensive energy consumption per ton of titanium). When using an inert anode, there is no CO2 emission from the anode reaction, resulting in zero direct carbon emissions (excluding indirect emissions from electricity generation), while the Kroll process emits approximately 25 tons of CO2 per ton of titanium. 2e .

[0060] Another specific embodiment of the present invention discloses a high-purity titanium prepared by the above method, wherein the high-purity titanium has an oxygen content ≤0.11% and a titanium purity greater than 99.30%.

[0061] The technical solution of the present invention will be further explained below with reference to specific embodiments.

[0062] Example 1 This embodiment discloses an apparatus for preparing high-purity titanium by electrolysis of titanium dioxide. The apparatus includes an electrolytic cell, which comprises, from the outside to the inside, a stainless steel shell 1, a heat insulation layer 2, a thermal insulation layer 3, and a graphite tank 4 connected in sequence. The inner cavity of the electrolytic cell is divided laterally by a first partition 5 and a second partition 6 into a preparatory tank 7, an anode chamber 8, and a cathode chamber 9. The top surfaces of the preparatory tank 7, the anode chamber 8, and the cathode chamber 9 are respectively provided with an independently controllable gas outlet 14 and a gas inlet 13. The upper end of the first partition 5 is sealed to the top surface of the electrolytic cell, the lower end of the first partition 5 is sealed to the bottom surface of the electrolytic cell, and the upper end of the second partition 6 is sealed to the top surface of the electrolytic cell. The preparatory tank 7 also includes a porous material storage chamber surrounded by a porous plate 15. The upper end of the porous plate 15 is sealed to the top surface of the electrolytic cell, and the lower end of the porous plate 15 is sealed to the bottom surface of the electrolytic cell. A preparatory tank feeding port 16 is provided on the top surface of the porous material storage chamber. The first partition plate 5 is provided with an upper one-way valve 10 and a lower one-way valve 11 with opposite directions from top to bottom to realize the directional flow of molten salt between the preparatory tank 7 and the anode chamber 8. A communication port is provided between the lower end of the second partition 6 and the bottom surface of the electrolytic cell. The communication port is filled with a liquid alloy layer 12 to form a liquid seal. The liquid alloy layer 12 also fills the bottom of the anode chamber 8 and the bottom of the cathode chamber 9. The lower end of the second partition 6 is immersed in the liquid alloy layer 12 so as to physically isolate the molten salt of the anode chamber 8 and the cathode chamber 9. The lower one-way valve 11 is above the upper surface of the liquid alloy layer 12. The lower one-way valve 11 only allows the molten salt of the preparation tank 7 to flow into the anode chamber 8, and the upper one-way valve 10 only allows the molten salt of the anode chamber 8 to flow into the preparation tank 7.

[0063] An anode 17 is disposed in the anode chamber 8, with its lower end immersed in molten anode salt. A cathode is disposed in the cathode chamber 9, with its lower end immersed in molten cathode salt. A cathode feed port 19 is also disposed on the top surface of the cathode chamber 9, and a cathode discharge port 27 is disposed at the lower end of the cathode chamber 9. A preparatory tank discharge port 26 is disposed at the lower end of the preparatory tank 7. In this embodiment, the parts of the graphite tank 4 that contact the molten salt, the parts of the first partition plate 5 and the second partition plate 6 that contact the molten salt, and the parts of the perforated plate 15 that contact the molten salt are all provided with an inner protective lining layer.

[0064] In a further embodiment, a sealed dual-chamber cathode cooling chamber is provided above the cathode chamber 9. The dual-chamber cathode cooling chamber includes a first cathode cooling chamber 20 and a second cathode cooling chamber 21. The first cathode cooling chamber 20 and the second cathode cooling chamber 21 share a cooling chamber partition 22. The cathode includes a first cathode 18 and a second cathode 212 connected in parallel.

[0065] A first cathode conductive rod 201 is provided in the first cathode cooling chamber 20. The upper end of the first cathode conductive rod 201 is connected to the negative terminal of the DC power supply, and the lower end of the first cathode conductive rod 201 is connected to the first cathode 18. The second cathode cooling chamber 21 is provided with a second cathode conductive rod 211, which is connected to the negative terminal of the DC power supply. The lower end of the second cathode conductive rod 211 is connected to a second cathode 212. The second cathode conductive rod 211 is a telescopic structure. The first cathode conductive rod 201 and the second cathode conductive rod 211 are connected in parallel.

[0066] More preferably, the first cathode cooling chamber 20 and the second cathode cooling chamber 21 are each provided with an air inlet 23, an air extraction port 24 and a vacuum valve 25.

[0067] Example 2 A method for preparing high-purity titanium by electrolyzing titanium dioxide using the apparatus of Example 1 is disclosed. 200g of anode electrolyte, a mixture of NaF and KF in a 1:1 mass ratio, is added to anode chamber 8. 200g of cathode electrolyte, a mixture of NaCl and KCl in a 1:1 mass ratio, is added to cathode chamber 9. Low-valence titanium chloride with an average valence of 2.2 is also added to cathode chamber 9, comprising 4% of the cathode electrolyte mass. High-purity graphite is used as anode 17, and a high-purity titanium rod is used as cathode. The liquid alloy layer 12 has a height of 5cm and is made from 400g of a mixture of Cu and Ti in a 72.5:27.5 mass ratio. The ratio of the interface area to the cathode reaction surface area of ​​the liquid alloy layer 12 is β=4. Electrolysis conditions: Anode current density 0.5 A·cm -2 Cathode current density 0.8 A·cm -2 Electrolysis was performed continuously for 12 hours.

[0068] The specific method includes the following steps: (a) Connect the positive and negative terminals of the external DC power supply to anode 17 and cathode respectively for electrolysis. Add titanium dioxide, 20g of titanium alloy waste (titanium content is 89%) and anode electrolyte to the molten salt in the preparatory tank 7 and dissolve them at 950°C under argon atmosphere. The titanium dioxide dissolves in the molten salt to generate tetravalent titanium ions, which react with the metallic titanium in the titanium alloy waste to generate low-valent titanium ions Ti. n+ , where n=2.3; In step (a), the mass ratio of titanium dioxide to anode electrolyte is 0.15, and the mass ratio of titanium dioxide to titanium in titanium alloy waste is 2. (b) By controlling the pressure difference between the preparatory tank 7 and the anode chamber 8, the low-valence titanium ions Ti are produced. n+ The molten salt circulates in a directional closed loop between the preparatory tank 7 and the anode chamber 8 through the upper one-way valve 10 and the lower one-way valve 11; Specifically, the pressure difference between the preparatory tank 7 and the anode chamber 8 is controlled by alternately pressurizing and depressurizing the gas inlet 13 and gas outlet 14 on the preparatory tank 7 and the anode chamber 8, and the lower one-way valve 11 is opened to release the low-valence titanium ions (Ti) from the preparatory tank 7. n+ Molten salt flows into anode chamber 8 until the molten salt level in anode chamber 8 reaches a predetermined height, i.e., 43% of the height of anode chamber 8, then the lower check valve 11 is closed; Monitor the concentration of titanium ions in the molten salt in the anode chamber 8. If the concentration of titanium ions is ≤0.2%, open the upper one-way valve 10 using the air pressure difference to allow the molten salt in the anode chamber 8 to flow into the preparation tank 7.

[0069] (c) During the electrolysis process, low-valence titanium ions Ti in the anode chamber 8 n+ At the interface of the liquid alloy layer 12, the titanium atoms are reduced to titanium atoms and enter the liquid alloy layer 12. At the interface of the liquid alloy layer 12 in the cathode chamber 9, the titanium atoms are oxidized to low-valence titanium ions (Ti). n+ Low-valence titanium ions (Ti) enter the cathode molten salt. n+ Titanium metal is produced by reduction precipitation on the cathode.

[0070] The optical photograph of metallic titanium obtained in this embodiment is as follows: Figure 2 As shown, this conforms to the state of electrolytic sponge titanium. The XRD pattern of metallic titanium is shown below. Figure 3 As shown, this proves that the product is composed of pure titanium.

[0071] Example 3 The method for preparing high-purity titanium by electrolytic titanium dioxide in this embodiment is similar to that in Example 2, except that the raw material for the liquid alloy layer 12 is 400g of a mixture of Cu, Ti and Ag in a mass ratio of 65.2:24.8:10.0, and the ratio of the interface area to the cathode reaction surface area of ​​the liquid alloy layer 12 is β=4. 200g of anode electrolyte is added to the anode chamber 8. The anode electrolyte is a mixture of NaF and K2TiF6 in a mass ratio of 64:36. 200g of cathode electrolyte is added to cathode chamber 9. The cathode electrolyte is a mixture of LiCl, KCl and NaCl in a mass ratio of 30:30:40. Low-valence titanium chloride with an average valence of 2.15 is also added to cathode chamber 9, accounting for 6% of the mass of the cathode electrolyte. Anode 17 is a copper-titanium alloy, and cathode is a high-purity titanium rod; Electrolysis conditions: Anode 17, current density 0.6 A·cm -2 Cathode current density 1.2 A·cm -2 Electrolysis was performed continuously for 12 hours.

[0072] In step (a), 20g of titanium alloy scrap is replaced with 24.5g of sponge titanium (99.5% titanium content), the mass ratio of titanium dioxide to anode electrolyte is 0.08, and the mass ratio of titanium dioxide to titanium in sponge titanium is 1.75; the molten salt is completely melted under argon protection at 900℃ to generate low-valence titanium ions Ti. n+ , where n=2.2.

[0073] Example 4 The method for preparing high-purity titanium by electrolytic titanium dioxide in this embodiment is similar to that in Example 2, except that the ratio of the interface area of ​​the liquid alloy layer 12 to the cathode reaction surface area is β=5 by changing the cathode size.

[0074] Example 5 The method for preparing high-purity titanium by electrolysis of titanium dioxide in this embodiment is similar to that in Example 2, except that the anode current density is 1.5 A·cm. -2 Cathode current density 0.4 A·cm -2 Electrolysis was performed continuously for 12 hours.

[0075] Comparative Example 1 The method for preparing high-purity titanium by electrolytic titanium dioxide in this comparative example is similar to that in Example 2, except that the ratio of the interface area of ​​the liquid alloy layer 12 to the cathode reaction surface area is β=6 by changing the cathode size.

[0076] Comparative Example 2 The method for preparing high-purity titanium by electrolysis of titanium dioxide in this comparative example is similar to that in Example 2. The difference is that the electrolytic cell does not have a preparatory cell 7, but uses two chambers, an anode chamber 8 and a cathode chamber 9, for electrolysis. TiO2 is directly added to the molten salt in the anode chamber 8.

[0077] Experimental Example 1 After the electrolysis reactions in Examples 2 to 5 and Comparative Examples 1 to 2 were completed, the prepared metallic titanium was sequentially subjected to 0.2 mol·L⁻¹ hydrochloric acid. -1 The titanium powder was obtained by ultrasonic treatment with hydrochloric acid for 30 minutes and ultrasonic treatment with ultrapure water for 30 minutes (repeated twice), followed by drying in a vacuum environment at 60℃ for 12 hours and weighing. The structure of the cathode-deposited metallic titanium was observed, the chemical composition of the titanium powder was detected, and the current efficiency was calculated. The relevant results are detailed in Table 1.

[0078] The current efficiency is defined as the ratio of the actual mass of the target product deposited during electrolysis to the theoretical mass calculated according to Faraday's law. The calculation method is as follows: The theoretical mass of titanium to be electrolyzed is calculated using the electrochemical equivalent of divalent titanium, the electrolysis time, and the current (for example, if the electrochemical equivalent of divalent titanium is 0.8928 g / Ah, with a current of 1 A and electrolysis for 1 h, the theoretical mass of titanium electrolyzed is 0.8928 g / Ah * 1 A * 1 h = 0.8928 g). The ratio of the obtained titanium mass to the theoretically electrolyzed titanium mass is the cathode current efficiency. Since the titanium electrolyzed at the cathode alloy on the cathode side should be divalent, this calculation is necessary.

[0079] Table 1

[0080] The titanium obtained by the method of this invention has a purity greater than 99.71%, an oxygen content ≤0.11%, and a current efficiency greater than 90.2%. In Comparative Example 1, when the cross-section of the cathode chamber 9 remains unchanged, if β is too large, it means that the cathode electrode size must be small enough. When the current remains unchanged, the current density will increase, the magnetohydrodynamic stability will decrease, the cathode lifetime will decrease, the concentration polarization will increase, resulting in a rise in voltage, an increase in power consumption, a decrease in current efficiency, and a change in the morphology of the titanium deposited on the cathode, with dendrites growing and becoming loose, and the interior containing fine black crystals.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for preparing high-purity titanium by electrolysis of titanium dioxide, characterized in that, The device includes an electrolytic cell, the inner cavity of which is divided laterally by a first partition and a second partition into a preparatory tank, an anode chamber and a cathode chamber. The first partition is provided with an upper one-way valve and a lower one-way valve in opposite directions from top to bottom, so as to realize the directional flow of molten salt between the preparatory tank and the anode chamber; A communication port is provided between the lower end of the second partition and the bottom surface of the electrolytic cell. The communication port is filled with a liquid alloy layer to form a liquid seal. The lower end of the second partition is immersed in the liquid alloy layer to physically isolate the molten salt between the anode chamber and the cathode chamber. The top surfaces of the preparatory tank, anode chamber, and cathode chamber are respectively provided with independent controllable gas outlets and gas inlets.

2. The apparatus according to claim 1, characterized in that, The upper end of the first partition is sealed to the top surface of the electrolytic cell, the lower end of the first partition is sealed to the bottom surface of the electrolytic cell, and the upper end of the second partition is sealed to the top surface of the electrolytic cell.

3. The apparatus according to claim 1, characterized in that, The liquid alloy layer also fills the bottom of the anode chamber and the bottom of the cathode chamber.

4. The apparatus according to claim 1, characterized in that, The preparation tank also includes a porous material placement cavity surrounded by a porous plate. The upper end of the porous plate is sealed to the top surface of the electrolytic cell, and the lower end of the porous plate is sealed to the bottom surface of the electrolytic cell.

5. The apparatus according to claim 4, characterized in that, The top surface of the porous material storage cavity is provided with a pre-filled groove.

6. The apparatus according to any one of claims 1-5, characterized in that, The lower one-way valve is higher than the upper surface of the liquid alloy layer, and the lower one-way valve only allows molten salt from the preparation tank to flow into the anode chamber. The upper one-way valve is higher than the height of the molten salt in the anode chamber, and the upper one-way valve only allows molten salt from the anode chamber to flow into the preparation tank.

7. The apparatus according to claim 1, characterized in that, The electrolytic cell comprises, from the outside in, a stainless steel shell, a heat insulation layer, a thermal insulation layer, and a graphite tank body connected in sequence.

8. The apparatus according to claim 1, characterized in that, An anode is provided in the anode chamber, and the lower end of the anode is immersed in anode molten salt. A cathode is provided in the cathode chamber, and the lower end of the cathode is immersed in cathode molten salt.

9. The apparatus according to claim 1, characterized in that, A sealed dual-chamber cathode cooling chamber is provided above the cathode chamber. The dual-chamber cathode cooling chamber includes a first cathode cooling chamber and a second cathode cooling chamber, and the first cathode cooling chamber and the second cathode cooling chamber share a cooling chamber partition.

10. A method for preparing high-purity titanium by electrolyzing titanium dioxide based on the apparatus of any one of claims 1-9.

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