Method for preparing high-purity titanium based on titanium anode dynamic dissolution titanium supply

Abstract

The invention relates to a method for preparing high-purity titanium through molten salt electrolysis based on titanium anode dynamic dissolution titanium supply, and belongs to the technical field of molten salt electrolytic refining. The preparation method comprises the following steps: mixing halide salt electrolytic molten salt and titanium sponge, dehydrating, heating and melting in a protective gas atmosphere to form a basic molten salt electrolysis system, introducing gaseous TiCl4 into the basic molten salt electrolysis system through carrier gas, and stirring and reacting for 30-60 minutes to generate Ti < 2 + > and Ti < 3 + > in the molten salt system, thereby obtaining a Ti < 2 + > / Ti < 3 + >-containing molten salt electrolysis system; the method comprises the following steps: by taking a titanium anode as a soluble anode and a metal or metal alloy as a cathode, continuously introducing gaseous TiCl4 into a molten salt electrolysis system containing Ti < 2 + > / Ti < 3 + > through carrier gas to adjust the total titanium ion concentration of Ti < 2 + > and Ti < 3 + > in the molten salt electrolysis system to be 3-6wt%, and carrying out constant-current electrolytic refining under the temperature condition of 50-150 DEG C above the halide salt electrolysis molten salt primary crystal temperature, so as to obtain the cathode high-purity metal titanium. According to the method, a titanium anode is used as a soluble anode for continuous electrochemical dissolution titanium supply, and gaseous TiCl4 is used for assisting titanium supply to be matched with a cathode deposition rate to realize titanium ion concentration self-balance.

Description

Technical Field

[0001] The invention relates to a method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, and belongs to the technical field of molten salt electrolytic refining. Background Art

[0002] At present, the Kroll method uses high-temperature magnesium to reduce TiCl4 to prepare sponge titanium. Although the technology is mature, it has problems such as high energy consumption, intermittent production and MgCl2 by-product pollution. The molten salt electrolysis method (including TiCl4 electrolysis and FFC Cambridge method) can reduce energy consumption, but it relies on high-priced titanium (Ti 4+ ) source leads to problems such as TiCl4 volatilization corrosion and low TiO2 reduction efficiency, and Ti 4+ It is easy to form insoluble oxychlorides (such as TiOCl2), which causes a decrease in electrolysis efficiency and cathode titanium oxide pollution, restricting the efficient and clean production of titanium.

[0003] In recent years, researchers have attempted to utilize titanium anodes to directly dissolve titanium. During the electrolysis process, titanium rods serve as titanium anodes, continuously replenishing titanium ions to the molten salt electrolyte through electrochemical dissolution, thereby avoiding the frequent addition of TiCl4. This can completely circumvent the traditional process's reliance on TiCl4 or TiO2 raw materials, and address the problems of raw material volatilization and oxygen contamination at the source. However, the dissolution rate of titanium anodes in existing technologies is not well matched to the electrolysis process, which can easily lead to excess or insufficient titanium ions, affecting the density and purity of the cathode titanium. Summary of the Invention

[0004] Aiming at the problem that the dissolution rate of the titanium anode is not compatible with the electrolysis process in the existing molten salt electrolysis using titanium anode to directly dissolve titanium, which easily leads to excess or insufficient titanium ions and affects the density and purity of cathode titanium, the present invention proposes a method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium. The method introduces gaseous TiCl4 into the liquid molten salt of the molten salt reaction unit through a carrier gas, constructs a gas-solid-liquid three-phase interface reaction system in an inert atmosphere at normal pressure, and causes a multiphase reduction reaction between the gaseous TiCl4 and the sponge titanium in the liquid molten salt to obtain Ti 2+ and Ti 3+ , using titanium anode as soluble anode to continuously supply titanium to the molten salt electrolysis system and maintaining the Ti content in the molten salt electrolysis system by adjusting the amount of gaseous TiCl4 added 2+ and Ti 3+ The total titanium ion concentration is 3~6wt% to accurately control the dynamic balance between the anode dissolution rate and the cathode deposition rate, thereby improving the density and purity of the cathode titanium.

[0005] A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, the specific steps are as follows: (1) The halide electrolytic molten salt and sponge titanium are mixed and dehydrated, and then heated and melted in a protective gas atmosphere to form a basic molten salt electrolysis system. Gaseous TiCl4 is introduced into the basic molten salt electrolysis system through a carrier gas and stirred for 30 to 60 minutes to generate Ti in the molten salt system. 2+ and Ti 3+ , and Ti-containing 2+ / Ti 3+ Molten salt electrolysis system; (2) Using titanium anode as soluble anode and metal or metal alloy as cathode, containing Ti 2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced by carrier gas to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 3~6wt%, and constant current electrolytic refining is carried out under the temperature condition of 50~150℃ above the primary crystallization temperature of halide electrolysis molten salt; the cathode is removed and washed with water to obtain high-purity metallic titanium at the cathode.

[0006] Preferably, the protective gas in step (1) is nitrogen or an inert gas, and the carrier gas and the protective gas are the same.

[0007] Preferably, the halide electrolysis molten salt in step (1) is one or more of NaCl, KCl, LiCl, MgCl2, and CaCl2.

[0008] Preferably, the amount of titanium sponge added in step (1) is 2-10 wt.% of the halide electrolysis molten salt.

[0009] Preferably, the dehydration treatment in step (1) adopts a step-by-step dehydration process, specifically comprising: uniformly heating the mixture of halide electrolytic molten salt and sponge titanium to a temperature of 90-120°C and drying to remove free water, then uniformly heating the mixture to a temperature of 280-350°C in a protective gas atmosphere and keeping the temperature for 2-4 hours to remove crystallized water.

[0010] More preferably, the uniform heating rate is 3-5°C / min.

[0011] Preferably, the titanium anode in step (2) is metallic titanium, titanium alloy, sponge titanium, titanium monoxide, titanium nitride, titanium carbide or titanium oxycarbide.

[0012] Preferably, the metal cathode in step (2) is titanium, tin, tungsten, molybdenum, nickel, zinc or bismuth, and the metal alloy cathode is an alloy composed of multiple metal elements among titanium, tin, tungsten, molybdenum, nickel, zinc and bismuth.

[0013] Preferably, in step (2), the initial crystallization temperature of the molten salt during electrolysis of the halide salt is 500-830°C, the constant current electrolytic refining temperature is 550-980°C, and the cathode current density during constant current electrolytic refining is 0.5-2.0 A / cm 2 ; The current density is preferably 1.0 A / cm 2 .

[0014] The beneficial effects of the present invention are: (1) The present invention constructs a gas-solid-liquid three-phase interface reaction system in an inert atmosphere at normal pressure, and TiCl4 vapor undergoes a multiphase reduction reaction with titanium sponge in liquid molten salt to generate Ti 2+ and Ti 3+ , improve Ti in molten salt system 2+ and Ti 3+ content, avoid Ti 4+ The formation of insoluble oxychloride TiOCl2 pollutes the electrolytic molten salt system; (2) The present invention uses the electrochemical dissolution of titanium anode as the main titanium source to directly provide low-valent titanium ions to the molten salt system, and transports gaseous TiCl4 through the carrier gas to adjust the Ti content in the molten salt electrolysis system. 2+ and Ti 3+ The total titanium ion concentration is 3~6wt%, and a dynamic equilibrium dual titanium source mechanism is constructed to achieve precise control and stable maintenance of the titanium ion concentration in the molten salt; (3) The dual titanium source synergistic control mechanism of the present invention, in which titanium is dissolved at the titanium anode to supply titanium and gaseous TiCl4 is transported by the carrier gas to supplement it, can increase the stability of titanium ion concentration by more than 50%, increase the current efficiency to more than 85%, and improve the deposition density and purity of cathode titanium. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the XRD pattern of the cathode metal titanium in Example 1. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0017] Example 1: A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, the specific steps are as follows: (1) 1000g of halide electrolytic molten salt (NaCl-KCl, NaCl accounts for 45wt% and KCl accounts for 55wt%) and 20g of sponge titanium were mixed and dehydrated, and then transferred into a sealed electrolytic cell. Under an argon atmosphere, they were heated to 700℃ and kept warm to melt to form a basic molten salt electrolysis system. Gaseous TiCl4 was introduced into the basic molten salt electrolysis system through a carrier gas (argon) and stirred for 60 minutes to generate Ti in the molten salt system. 2+and Ti 3+ , and Ti-containing 2+ / Ti 3+ The dehydration treatment adopts a step-by-step dehydration process, specifically comprising: heating the mixture of halide electrolytic molten salt (NaCl-KCl) and sponge titanium uniformly at a heating rate of 3°C / min to a temperature of 100°C, drying to remove free water, and then heating the mixture uniformly at a heating rate of 3°C / min to a temperature of 300°C under an argon atmosphere and keeping the temperature for 4 hours to remove crystallized water; (2) Using titanium anode (titanium rod) as soluble anode and tungsten rod as cathode, containing Ti 2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced by carrier gas (argon) to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 3~4wt%, and the constant current electrolytic refining is carried out at a temperature of 700℃ for 4h (cathode current density is 0.5A / cm 2 ); Take out the cathode and wash it with water to obtain high-purity titanium metal at the cathode; The XRD pattern of the cathode high-purity titanium in this embodiment is shown in FIG. Figure 1 ,from Figure 1 It can be seen that the cathode product is a relatively pure metallic titanium phase without other impurity phases; The purity of the high-purity titanium metal used in the cathode of this embodiment is 99.83 wt %.

[0018] Example 2: A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, the specific steps are as follows: (1) 1000g of halide electrolytic molten salt (NaCl-KCl, NaCl accounts for 45wt% and KCl accounts for 55wt%) and 40g of sponge titanium were mixed and dehydrated, and then transferred into a sealed electrolytic cell. Under a nitrogen atmosphere, they were heated to 750℃ and kept warm to melt to form a basic molten salt electrolysis system. Gaseous TiCl4 was introduced into the basic molten salt electrolysis system through a carrier gas (nitrogen) and stirred for 40 minutes to generate Ti in the molten salt system. 2+ and Ti 3+ , and Ti-containing 2+ / Ti 3+ The dehydration treatment adopts a step-by-step dehydration process, specifically comprising: heating a mixture of halide electrolytic molten salt (NaCl-KCl) and sponge titanium at a heating rate of 4°C / min to a temperature of 120°C, drying to remove free water, and then heating the mixture at a heating rate of 4°C / min to a temperature of 320°C under an argon atmosphere for 3.5 hours to remove crystallized water; (2) Using titanium anode (titanium alloy) as soluble anode and titanium rod as cathode, containing Ti2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced through the carrier gas (nitrogen) to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 4~5wt%, and the constant current electrolytic refining is carried out at a temperature of 750℃ for 3.5h (cathode current density is 0.75A / cm 2 ); Take out the cathode and wash it with water to obtain high-purity titanium metal at the cathode; The purity of the high-purity titanium metal used in the cathode of this embodiment is 99.75 wt %.

[0019] Example 3: A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, the specific steps are as follows: (1) 1000g of halide electrolytic molten salt (LiCl-KCl, LiCl accounts for 50wt.%, KCl accounts for 50wt.%) and 60g of sponge titanium were mixed and dehydrated, and then transferred into a sealed electrolytic cell. Under an argon atmosphere, they were heated to 800℃ and kept warm to melt to form a basic molten salt electrolysis system. Gaseous TiCl4 was introduced into the basic molten salt electrolysis system through a carrier gas (argon) and stirred for 50min to generate Ti in the molten salt system. 2+ and Ti 3+ , and Ti-containing 2+ / Ti 3+ The dehydration treatment adopts a step-by-step dehydration process, specifically comprising: heating a mixture of halide electrolytic molten salt (LiCl-KCl) and sponge titanium at a heating rate of 3.5°C / min to a temperature of 90°C, drying to remove free water, and then heating the mixture at a heating rate of 3.5°C / min to a temperature of 350°C in an argon atmosphere, and keeping the temperature for 3.5 hours to remove crystallized water; (2) Using titanium anode (sponge titanium) as soluble anode and molybdenum rod as cathode, containing Ti 2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced by carrier gas (argon) to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 3.5~4wt%, and the product is electrolytically refined at a constant current for 3h at a temperature of 800℃ (cathode current density of 1.0 A / cm 2 ); Take out the cathode and wash it with water to obtain high-purity titanium metal at the cathode; The purity of the high-purity titanium metal used in the cathode of this embodiment is 99.86 wt %.

[0020] Example 4: A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, the specific steps are as follows: (1) 1000g of halide electrolytic molten salt (NaCl-LiCl-KCl, NaCl accounts for 30wt%, LiCl accounts for 25wt%, and KCl accounts for 45wt%) and 80g of sponge titanium were mixed and dehydrated, and then transferred into a sealed electrolytic cell. Under an argon atmosphere, they were heated to 850℃ and kept warm to melt to form a basic molten salt electrolysis system. Gaseous TiCl4 was introduced into the basic molten salt electrolysis system through a carrier gas (argon) and stirred for 40 minutes to generate Ti in the molten salt system. 2+ and Ti 3+ , and Ti-containing 2+ / Ti 3+ The dehydration treatment adopts a step-by-step dehydration process, specifically comprising: heating a mixture of halide electrolytic molten salt (NaCl-LiCl-KCl) and sponge titanium at a heating rate of 5°C / min to a temperature of 110°C, drying to remove free water, and then heating the mixture at a heating rate of 5°C / min to a temperature of 300°C in an argon atmosphere for 4 hours to remove crystallized water; (2) Using titanium anode (titanium nitride) as soluble anode and nickel rod as cathode, containing Ti 2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced by carrier gas (argon) to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 5~5.5wt%, and the constant current electrolytic refining is carried out at a temperature of 800℃ for 2.5h (cathode current density is 1.25A / cm 2 ); Take out the cathode and wash it with water to obtain high-purity titanium metal at the cathode; The purity of the high-purity titanium metal used in the cathode of this embodiment is 99.65 wt%.

[0021] Example 5: A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anode to supply titanium, the specific steps are as follows: (1) 1000g of halide electrolytic molten salt (CaCl2-NaCl, CaCl2 accounts for 60wt.%, NaCl accounts for 40wt%) and 100g of sponge titanium were mixed and dehydrated, and then transferred into a sealed electrolytic cell. Under an argon atmosphere, they were heated to 900℃ and kept warm to melt to form a basic molten salt electrolysis system. Gaseous TiCl4 was introduced into the basic molten salt electrolysis system through a carrier gas (argon) and stirred for 30 minutes to generate Ti in the molten salt system. 2+ and Ti 3+ , and Ti-containing 2+ / Ti 3+The dehydration treatment adopts a step-by-step dehydration process, specifically comprising: heating the mixture of halide electrolytic molten salt (CaCl2-NaCl) and sponge titanium uniformly at a heating rate of 4°C / min to 100°C, drying to remove free water, and then heating the mixture uniformly at a heating rate of 4°C / min to 320°C under an argon atmosphere and keeping the temperature for 3.5 hours to remove crystallized water; (2) Using titanium anode (titanium monoxide) as soluble anode and bismuth rod as cathode, containing Ti 2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced by carrier gas (argon) to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 5~6wt%, and the constant current electrolytic refining is carried out at a temperature of 850℃ for 3.5h (cathode current density is 2.0A / cm 2 ); Take out the cathode and wash it with water to obtain high-purity titanium metal at the cathode; The purity of the high-purity titanium metal used in the cathode of this embodiment is 99.72 wt %.

[0022] The above describes the specific embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes, characterized in that: The specific steps are as follows: (1) The halide electrolytic molten salt and sponge titanium are mixed and dehydrated, and then heated and melted in a protective gas atmosphere to form a basic molten salt electrolysis system. Gaseous TiCl4 is introduced into the basic molten salt electrolysis system through a carrier gas and stirred for 30 to 60 minutes to generate Ti in the molten salt system. 2+ and Ti 3+ , and Ti-containing 2+ / Ti 3+ Molten salt electrolysis system; (2) Using titanium anode as soluble anode and metal or metal alloy as cathode, containing Ti 2+ / Ti 3+ The TiCl4 in the molten salt electrolysis system is continuously introduced by carrier gas to adjust the Ti 2+ and Ti 3+ The total titanium ion concentration is 3~6wt%, and constant current electrolytic refining is carried out under the temperature condition of 50~150℃ above the primary crystallization temperature of halide electrolysis molten salt; the cathode is removed and washed with water to obtain high-purity metallic titanium at the cathode.

2. The method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes according to claim 1, characterized in that: In step (1), the protective gas is nitrogen or an inert gas, and the carrier gas and the protective gas are the same.

3. The method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes according to claim 1, characterized in that: The molten salt in step (1) halide electrolysis is one or more of NaCl, KCl, LiCl, MgCl2, and CaCl2.

4. The method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes according to claim 1, characterized in that: In step (1), the amount of titanium sponge added is 2-10 wt.% of the halide electrolysis molten salt.

5. The method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes according to claim 1, characterized in that: The titanium anode in step (2) is metallic titanium, titanium alloy, titanium sponge, titanium monoxide, titanium nitride, titanium carbide or titanium oxycarbide.

6. The method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes according to claim 1, characterized in that: In step (2), the metal cathode is titanium, tin, tungsten, molybdenum, nickel, zinc or bismuth, and the metal alloy cathode is an alloy composed of multiple metal elements among titanium, tin, tungsten, molybdenum, nickel, zinc and bismuth.

7. The method for preparing high-purity titanium by molten salt electrolysis based on dynamic dissolution of titanium anodes according to claim 1, characterized in that: Step (2) The initial crystallization temperature of the molten salt during electrolysis of the halide salt is 500-830°C, the constant current electrolytic refining temperature is 550-980°C, and the cathode current density of the constant current electrolytic refining is 0.5-2.0A / cm 2 .

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