Waste titanium-niobium alloy recovery method

Abstract

The invention provides a waste titanium-niobium alloy recovery method which can comprise the following steps: by taking waste titanium-niobium alloy as an anode, TiCl2-containing mixed molten salt as an electrolyte and liquid tin as a cathode, carrying out electrolysis at the temperature of 750-1000 DEG C and the voltage of 1.0-2.5 V, and collecting the titanium-tin alloy of the cathode and a niobium-containing anode scrap after the electrolysis is completed; the titanium-tin alloy of the cathode is subjected to vacuum distillation, and metal titanium and metal tin are obtained respectively; and the anode scrap containing niobium is subjected to electrolytic refining, and metal niobium is obtained. According to the method, the technological process is greatly simplified, the core separation step is completed through one-step electrolysis, the tedious process and a large amount of waste liquid discharge of a wet process are avoided, meanwhile, the use of corrosive reagents in an iodization method is eradicated, and the method is environmentally friendly and high in safety.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and more specifically, to a method for recycling waste titanium-niobium alloy. Background Technology

[0002] Titanium-niobium alloys are widely used as low-temperature superconducting materials due to their excellent superconducting properties, outstanding mechanical characteristics, and relatively reasonable manufacturing costs. They are primarily applied in fields such as biomedicine (e.g., nuclear magnetic resonance imaging), high-energy physics (e.g., particle accelerators), and electrical engineering. However, the production and practical use of titanium-niobium alloys generate a considerable amount of waste alloy material. How to efficiently and environmentally recycle the valuable metal elements within these alloys to achieve sustainable resource recycling has become a current research hotspot.

[0003] Currently, the main methods for recycling waste titanium-niobium alloys include wet recycling and iodination recycling. Wet recycling typically involves steps such as acid leaching, hydrogenation, fine grinding, mixed alkali roasting, water leaching, and re-acid leaching to ultimately convert the alloy into titanium dioxide and niobium pentoxide. This method is relatively cumbersome and generates a significant amount of waste liquid, with the resulting products being metal oxides that require further smelting to obtain the elemental metals. Iodination recycling utilizes the reaction of iodine vapor with the titanium-niobium alloy to generate the corresponding iodides. Titanium iodide and niobium iodide are then separated by distillation, and finally, elemental titanium and niobium are obtained through thermal decomposition. Although iodination can directly produce metals, the highly corrosive nature of iodine vapor places stringent requirements on equipment materials, and the operation poses certain safety and environmental risks. Therefore, developing a recycling method with a short process flow, low energy consumption, environmental friendliness, and the ability to directly obtain high-purity titanium and niobium is of great significance for promoting resource recycling and green manufacturing. Summary of the Invention

[0004] In view of the shortcomings of the prior art, one of the objectives of this invention is to solve one or more problems existing in the prior art. For example, one objective of this invention is to provide a waste titanium-niobium alloy recycling method with a short process flow, low energy consumption, environmental friendliness, and the ability to directly obtain metallic titanium and metallic niobium.

[0005] This invention provides a method for recycling waste titanium-niobium alloy, which may include the following steps: using waste titanium-niobium alloy as the anode, a mixed molten salt containing TiCl2 as the electrolyte, and liquid tin as the cathode, electrolysis is performed at a temperature of 750℃~1000℃ and a voltage of 1.0V~2.5V; after electrolysis, the titanium-tin alloy from the cathode and the niobium-containing residual anode are collected; the titanium-tin alloy from the cathode is vacuum distilled to obtain metallic titanium and metallic tin respectively; the niobium-containing residual anode is electrolytically refined to obtain metallic niobium.

[0006] Furthermore, vacuum distillation of the titanium-tin alloy of the cathode may include placing the titanium-tin alloy of the cathode at a temperature of 1000℃~1300℃ and a vacuum degree of 10. -1 Pa~10 2 Vacuum distillation was performed under Pa conditions, and metallic titanium and metallic tin were obtained after distillation.

[0007] Furthermore, the purity of metallic titanium is not less than 99%, and the purity of metallic tin is not less than 99.99%.

[0008] Furthermore, electrolytic refining of niobium-containing residual anodes may include: preparing a mixed molten salt containing NbCl2; using the mixed molten salt containing NbCl2 as the electrolyte and the niobium-containing residual anode as the anode, electrolyzing at a temperature of 800℃~1000℃ and applying a voltage of 1.8V~2.5V; after electrolysis, removing the cathode to obtain metallic niobium.

[0009] Furthermore, the mixed molten salt containing NbCl2 can be a NaCl-KCl-NbCl2 mixed molten salt, wherein the mass of NbCl2 can be 2% to 5% of the total mass of the mixed molten salt.

[0010] Furthermore, the process may also include drying and crushing the niobium-containing residual anode before electrolysis, wherein the drying temperature can be 50℃~70℃, the drying vacuum degree can be 0.5MPa~1MPa, and the particle size of the crushed niobium-containing residual anode can be 5mm~10mm.

[0011] Furthermore, the mixed molten salt containing TiCl2 can be a NaCl-KCl-TiCl2 mixed molten salt, wherein the mass of TiCl2 can be 2% to 5% of the total mass of the mixed molten salt.

[0012] Furthermore, the purity of metallic niobium is not less than 99.5%.

[0013] Compared with the prior art, the beneficial effects of the present invention include at least the following: the method of the present invention can directly obtain high-purity metallic titanium and niobium without further processing of their oxides, thus significantly improving the product value; the process flow is greatly simplified, with the core separation step completed by one-step electrolysis, avoiding the lengthy process and large amount of waste liquid discharge of the wet process, while eliminating the use of corrosive reagents in the iodination method, making it environmentally friendly and highly safe. Detailed Implementation

[0014] In the following, a method for recycling waste titanium-niobium alloy according to the present invention will be described in detail with reference to exemplary embodiments.

[0015] Specifically, this invention provides a method for recycling waste titanium-niobium alloys based on molten salt electrolysis, vacuum distillation, and electrolytic refining. This method utilizes the unique affinity between tin liquid cathode and titanium. During molten salt electrolysis, titanium is selectively and electrochemically extracted from the waste titanium-niobium alloy to the tin liquid phase, forming a titanium-tin alloy (Ti-Sn alloy). Niobium, due to its different electrochemical behavior, remains at the anode, forming a niobium-rich residual anode, thus achieving efficient separation of titanium and niobium. The resulting titanium-tin alloy is then subjected to vacuum distillation to separate and recover high-purity metallic titanium and metallic tin. The tin can be returned to the system as a liquid cathode for recycling. The niobium-rich residual anode, after being crushed, is transferred to another molten salt electrolysis system for electrolytic refining, ultimately yielding high-purity metallic niobium (Nb).

[0016] This invention provides a method for recycling waste titanium-niobium alloys. In some embodiments, the method for recycling waste titanium-niobium alloys may include the following steps:

[0017] S01 uses waste titanium-niobium alloy as the anode, mixed molten salt containing TiCl2 as the electrolyte, and liquid tin as the cathode. Electrolysis is carried out at a temperature of 750℃~1000℃ and a voltage of 1.0V~2.5V. After electrolysis, the titanium-tin alloy of the cathode and the residual anode containing niobium are collected.

[0018] S02, vacuum distillation of the titanium-tin alloy of the cathode, to obtain metallic titanium and metallic tin respectively;

[0019] SO3 is used to electrolytically refine the niobium-containing residual anode to obtain metallic niobium.

[0020] In some embodiments, the TiCl2-containing mixed molten salt can be a mixed molten salt composed of alkali metal chloride and titanium dichloride. The presence of TiCl2 in the mixed molten salt can reduce electrode concentration polarization and lower the electrolysis voltage. In some embodiments, the TiCl2-containing mixed molten salt can be a NaCl-KCl-TiCl2 mixed molten salt. NaCl and KCl can be prepared in a 1:1 molar ratio, which can reduce the melting temperature of the mixed molten salt. The mass of TiCl2 can be 2% to 5% of the total mass of the mixed molten salt. Setting the addition of 2%-5% TiCl2 can suppress polarization and reduce the generation of overpotential. If the addition of TiCl2 exceeds 5%, Ti... 2+ Ti will be generated due to anodic oxidation 3+ or Ti 4+ This leads to a decrease in current efficiency. For example, the mass of TiCl2 can be 3% to 4% of the total mass of the mixed molten salt. Another example is that the mass of TiCl2 can be 3.5% of the total mass of the mixed molten salt.

[0021] In some implementations, the mixed molten salt containing TiCl2 can be dried before electrolyzing the waste titanium-niobium alloy to remove moisture, prevent side reactions, and improve electrolysis efficiency. The drying temperature can be 200℃~300℃, and the vacuum degree <100Pa. For example, the drying temperature can be 250℃, and the vacuum degree can be 50Pa.

[0022] In some implementations, the electrolysis temperature in step S01 can be 780℃~950℃, and the voltage can be 1.2V~2.3V. For example, the electrolysis temperature can be 810℃~920℃, and the voltage can be 1.5V~2.0V; another example is that the electrolysis temperature can be 840℃~880℃, and the voltage can be 1.7V~1.8V.

[0023] In some implementations, the titanium-tin alloy of the cathode can be a mixture of Ti6Sn5 and β-Sn. Of course, due to differences in electrolysis temperature, voltage, and electrolysis time, the titanium-tin alloy of the cathode can also be an alloy composed of other chemical formulas.

[0024] In some embodiments, vacuum distillation of the titanium-tin alloy of the cathode may include placing the titanium-tin alloy of the cathode at a temperature of 1000°C to 1300°C and a vacuum degree of 10. -1 Pa~10 2 Vacuum distillation is performed under a pressure of Pa, yielding metallic titanium and metallic tin. For example, the obtained titanium-tin alloy can be placed in a titanium crucible, which is then fitted with a quartz tube. A dual-temperature zone tubular furnace with an external vacuum pump is used for vacuum separation. Vacuum separation allows for the directional separation of the titanium-tin alloy into metallic Ti and metallic Sn. In some embodiments, the vacuum separation temperature can be 1050℃~1280℃, with a vacuum degree of 10Pa~90Pa; or the temperature can be 1080℃~1200℃, with a vacuum degree of 25Pa~75Pa; or the temperature can be 1120℃~1170℃, with a vacuum degree of 38Pa~58Pa; or a combination of these ranges. In some embodiments, the metallic tin obtained in step S02 can be recycled as the liquid tin cathode from step S01, effectively reducing raw material costs and achieving closed-loop operation of key materials.

[0025] In some implementation schemes, the purity of titanium is not less than 99%, and the purity of tin is not less than 99.99%.

[0026] In some implementations, electrolytic refining of niobium-containing residual anodes may include:

[0027] S031, prepare a mixed molten salt containing NbCl2;

[0028] SO32 uses a mixed molten salt containing NbCl2 as the electrolyte and a niobium-containing residual anode as the anode. Electrolysis is performed at a temperature of 800℃~1000℃ with a voltage of 1.8V~2.5V. After electrolysis, the cathode is removed to obtain metallic niobium.

[0029] For example, in some embodiments, electrolytic refining of niobium-containing residual anodes may include:

[0030] Step (1): Remove the niobium-rich residual anode, wash it with water to remove the molten salt on the anode surface, place it in a drying oven for drying, and then crush it. For example, the drying temperature can be 50℃~70℃, and the drying vacuum degree can be 0.5MPa~1MPa. Another example is that the drying temperature can be 60℃, and the vacuum degree can be 0.8MPa. The particle size of the crushed niobium-containing residual anode can be 5mm~10mm. For example, the particle size of the crushed niobium-containing residual anode can be a combination of 6mm~9mm, 7mm~8mm, or larger.

[0031] Step (2): The crushed niobium-rich residual anode is loaded into a graphite crucible, which is then connected with a wire to serve as the anode. The wire can be molybdenum wire, etc. The graphite crucible can be a high-purity graphite crucible.

[0032] Step (3) involves preparing a mixed molten salt containing NbCl2 and drying it. The dried mixed molten salt is then placed in a new reactor, using the anode prepared in step (2) as the anode and a molybdenum mesh as the cathode for electrolytic refining. The electrolysis temperature can be 820℃~980℃, and the applied voltage can be 1.9V~2.3V. For example, the electrolysis temperature can be 840℃~950℃, and the applied voltage can be 2.0V~2.2V. Another example is an electrolysis temperature of 900℃ and an applied voltage of 2.1V.

[0033] Step (4): After electrolysis, the molybdenum mesh cathode is removed, cooled in an Ar atmosphere, and finally cleaned by ultrasonication to obtain metallic Nb. The purity of the metallic Nb product is not less than 99.5%.

[0034] In some embodiments, the NbCl2-containing mixed molten salt can be a NaCl-KCl-NbCl2 mixed molten salt. The presence of NbCl2 in the mixed molten salt can reduce electrode concentration polarization during the refining process and lower the electrolytic refining voltage. In some embodiments, the NaCl and KCl in the NaCl-KCl-NbCl2 mixed molten salt can be configured in a 1:1 molar ratio, which can reduce the melting temperature of the mixed molten salt. In some embodiments, the mass of NbCl2 can be 2% to 5% of the total mass of the mixed molten salt. Setting the addition amount of 2%-5% NbCl2 can suppress polarization and reduce the generation of overpotential. For example, the mass of NbCl2 can be 3% to 4% of the total mass of the mixed molten salt. As another example, the mass of NbCl2 can be 3.5% of the total mass of the mixed molten salt.

[0035] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0036] Example 1

[0037] A method for recycling waste titanium-niobium alloys may include the following steps:

[0038] Step 1: Cut the waste titanium-niobium alloy (composition: Ti-50wt% Nb) into 20mm×20mm×5mm blocks to be used as anodes. Prepare a mixed molten salt by weighing a mixture of 175.5g NaCl, 223.5g KCl (molar ratio 1:1), and 20.0g TiCl2. Dry the mixed molten salt at 250℃ and 50Pa vacuum for 12 hours.

[0039] Step 2: Place the dried mixed molten salt in a reactor and heat to 800℃ under argon protection to melt it. Use waste titanium-niobium alloy blocks as the anode and 200g of high-purity liquid tin (99.99%) as the cathode. Apply a DC voltage of 1.5V and electrolyze for 48 hours. After electrolysis, remove and cool the cathode to obtain Sn-Ti alloy ingots.

[0040] Step 3: Place the Sn-Ti alloy ingot into a titanium crucible and then into a dual-temperature zone tube furnace. After evacuating the system to 1 Pa, hold it at 1100℃ for 6 hours. Collect metallic tin in the cooling section of the tube furnace, and recover the remaining metallic titanium in the titanium crucible.

[0041] Step 4: Wash, dry, and crush the niobium-rich residual anode from Step 2 into 5mm-8mm particles. Prepare a NaCl-KCl-NbCl2 molten salt (NbCl2 concentration 5.0wt%), and electrolyze at 850℃ using the crushed niobium-rich residual anode as the anode and a molybdenum mesh as the cathode, applying a voltage of 2.0V for 24 hours. After electrolysis, remove the cathode, cool, and clean it to obtain metallic niobium.

[0042] The purity of the tin metal obtained in step 3 was determined by ICP-MS, and the purity was 99.995%. The purity of the titanium metal obtained in step 3 was determined by GDMS analysis, and the purity was 99.3%. The purity of the niobium metal obtained in step 4 was determined by ICP analysis, and the purity was 99.6%.

[0043] Example 2

[0044] A method for recycling waste titanium-niobium alloys may include the following steps:

[0045] Step 1: Cut the waste titanium-niobium alloy (composition: Ti-50wt% Nb) into 20mm×20mm×5mm blocks to be used as anodes. Weigh 175.5g of NaCl, 223.5g of KCl (molar ratio 1:1), and 20.0g of TiCl2 and mix them to prepare a mixed molten salt. Dry the mixed molten salt at 250℃ and a vacuum of 50Pa for 12 hours.

[0046] Step 2: Place the dried mixed molten salt in a reactor and heat to 900℃ under argon protection to melt. Use waste titanium-niobium alloy blocks as the anode and 200g of high-purity liquid tin (99.99%) as the cathode. Apply a DC voltage of 2.0V and electrolyze for 36 hours. After electrolysis, remove and cool the cathode to obtain Sn-Ti alloy ingots.

[0047] Step 3: Place the Sn-Ti alloy ingot into a titanium crucible and then into a dual-temperature zone tube furnace. After evacuating the system to 10 Pa, hold it at 1200℃ for 4 hours. Collect metallic tin in the cooling section of the tube furnace, and recover the residual metallic titanium in the titanium crucible.

[0048] Step 4: Wash, dry, and crush the niobium-rich residual anode from Step 2 into 5-8 mm particles. Prepare a NaCl-KCl-NbCl2 molten salt (NbCl2 concentration 3.0 wt%), and electrolyze at 900℃ using the crushed niobium-rich residual anode as the anode and a molybdenum mesh as the cathode, applying a voltage of 2.2 V for 24 hours. After electrolysis, remove the cathode, cool, and clean it to obtain metallic niobium.

[0049] The purity of the tin metal obtained in step 3 was determined by ICP-MS, and the purity was 99.993%. The purity of the titanium metal obtained in step 3 was determined by GDMS analysis, and the purity was 99.5%. The purity of the niobium metal obtained in step 4 was determined by ICP analysis, and the purity was 99.55%.

[0050] Example 3

[0051] A method for recycling waste titanium-niobium alloys may include the following steps:

[0052] Step 1: Cut the waste titanium-niobium alloy (composition: Ti-50wt% Nb) into 20mm×20mm×5mm blocks to be used as anodes. Prepare a mixed molten salt by weighing a mixture of 175.5g NaCl, 223.5g KCl (molar ratio 1:1), and 20.0g TiCl2. Dry the mixed molten salt at 250℃ and 50Pa vacuum for 12 hours.

[0053] Step 2: Place the dried mixed molten salt in a reactor and heat to 750℃ under argon protection to melt. Use waste titanium-niobium alloy blocks as the anode and 200g of high-purity liquid tin (99.99%) as the cathode. Apply a DC voltage of 1.2V and electrolyze for 60 hours. After electrolysis, remove and cool the cathode to obtain Sn-Ti alloy ingots.

[0054] Step 3: Place the Sn-Ti alloy ingot into a titanium crucible and then into a dual-temperature zone tube furnace. After evacuating the system to 0.5 Pa, hold it at 1000℃ for 8 hours. Collect metallic tin in the cooling section of the tube furnace, and recover the residual metallic titanium in the titanium crucible.

[0055] Step 4: Wash, dry, and crush the niobium-rich residual anode from Step 2 into 5-8 mm particles. Prepare a NaCl-KCl-NbCl2 molten salt (NbCl2 concentration 5.0 wt%), and electrolyze at 850℃ using the crushed niobium-rich residual anode as the anode and a molybdenum mesh as the cathode, applying a voltage of 1.8 V for 24 hours. After electrolysis, remove the cathode, cool, and clean it to obtain metallic niobium.

[0056] The purity of the tin metal obtained in step 3 was determined by ICP-MS, and the purity was 99.997%. The purity of the titanium metal obtained in step 3 was determined by GDMS analysis, and the purity was 99.1%. The purity of the niobium metal obtained in step 4 was determined by ICP analysis, and the purity was 99.5%.

[0057] Although the invention has been described above in conjunction with exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the exemplary embodiments of the invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for recycling waste titanium-niobium alloy, characterized in that, Includes the following steps: Using waste titanium-niobium alloy as the anode, mixed molten salt containing TiCl2 as the electrolyte, and liquid tin as the cathode, electrolysis was carried out at a temperature of 750℃~1000℃ and a voltage of 1.0V~2.5V. After electrolysis, the titanium-tin alloy of the cathode and the residual anode containing niobium were collected. The titanium-tin alloy of the cathode was vacuum distilled to obtain metallic titanium and metallic tin, respectively. Electrolytic refining of the niobium-containing residual anode yields metallic niobium.

2. The method for recycling waste titanium-niobium alloy according to claim 1, characterized in that, Vacuum distillation of the titanium-tin alloy at the cathode involves placing the titanium-tin alloy at a temperature of 1000℃~1300℃ and a vacuum degree of 10. -1 Pa~10 2 Vacuum distillation was performed under Pa conditions, and metallic titanium and metallic tin were obtained after distillation.

3. The method for recycling waste titanium-niobium alloy according to claim 1 or 2, characterized in that, The purity of metallic titanium is not less than 99%, and the purity of metallic tin is not less than 99.99%.

4. The method for recycling waste titanium-niobium alloy according to claim 1 or 2, characterized in that, Electrolytic refining of niobium-containing residual anodes includes: Prepare a mixed molten salt containing NbCl2; Using a mixed molten salt containing NbCl2 as the electrolyte and a niobium-containing residual anode as the anode, electrolysis was performed at a temperature of 800℃~1000℃ with a voltage of 1.8V~2.5V. After electrolysis, the cathode was removed to obtain metallic niobium.

5. The method for recycling waste titanium-niobium alloy according to claim 4, characterized in that, The NbCl2-containing mixed molten salt is a NaCl-KCl-NbCl2 mixed molten salt, wherein the mass of NbCl2 is 2% to 5% of the total mass of the mixed molten salt.

6. The method for recycling waste titanium-niobium alloy according to claim 4, characterized in that, It also includes drying and crushing the niobium-containing residual anode before electrolysis, wherein the drying temperature is 50℃~70℃ and the drying vacuum degree is 0.5MPa~1MPa; the particle size of the crushed niobium-containing residual anode is 5mm~10mm.

7. The method for recycling waste titanium-niobium alloy according to claim 1, 2, 5 or 6, characterized in that, The mixed molten salt containing TiCl2 is a NaCl-KCl-TiCl2 mixed molten salt, wherein the mass of TiCl2 is 2% to 5% of the total mass of the mixed molten salt.

8. The method for recycling waste titanium-niobium alloy according to claim 1, 2, 5 or 6, characterized in that, The purity of metallic niobium is not less than 99.5%.