CN108441892A - The method of metastable state high temperature fused salt electrolysis refining high purity titanium based on complex ion - Google Patents

Abstract

The invention discloses a metastable high-temperature molten salt electrolytic refining method for high-purity titanium based on complex ions. In the metastable high-temperature molten salt, the titanium ions in the titanium ion source exist in the form of complex ions, wherein the titanium ions include high-valent titanium ions and low-valent titanium ions. The presence of complex ions can reduce the power consumption loss caused by the disproportionation reaction of titanium ions. High-purity titanium is obtained by electrolytic refining in metastable molten salt, the purity of which can meet the requirements of 4N5-5N, and the electrolytic efficiency is greater than 90%.

Description

Metastable high-temperature molten salt electrolytic refining method for high-purity titanium based on complex ions

technical field

The invention belongs to the technical field of metallurgy, and in particular relates to a method for electrolytically refining high-purity titanium with metastable high-temperature molten salt based on complex ions.

Background technique

High-purity titanium has excellent properties such as light weight, corrosion resistance, and low resistivity. It is mainly used in large-scale integrated circuit manufacturing, high-end new titanium alloys and other industries. It is a strategic key material necessary for electrical, electronics, and aerospace. , National defense construction plays a vital role. As a sputtering target for manufacturing large-scale integrated circuits, high-purity titanium requires a purity of 4N5 (99.995%) to 6N (99.9999%), with an oxygen content below 200ppm and a metal impurity content below 10ppm. However, the current technology for preparing high-purity titanium is immature, which to a considerable extent leads to the high price of high-purity titanium, which directly leads to its lack of large-scale application.

Among the many preparation technologies of high-purity titanium, the molten salt electrolysis process, which is simple and easy to realize continuous process, has very broad application prospects and has attracted much attention. The molten salt electrolysis method is to extract high-purity titanium by using electrochemical principles. Usually, coarse titanium, titanium alloy or titanium compound is used as the anode, and the raw material titanium is dissolved into the electrolyte under a certain precipitation potential, and high-purity titanium is precipitated at the cathode. During the electrolysis process, impurities with a higher stripping potential than titanium remain on the anode or precipitate in the electrolyte, and impurities with a lower stripping potential than titanium also dissolve into the electrolyte together with titanium.例如，专利文献CN102517611A、CN104947152A公开了有关熔盐电解法提炼高纯钛的技术方案，专利文献CN102230193A、CN103014775A、CN104928719A、CN105568320A、CN201605337U、CN204982083U、CN204874773U与CN205653517U公开了有关熔盐电解精炼高纯钛的equipment. However, in the prior art, the technical scheme of using molten salt electrolytic refining of high-purity titanium generally uses alkali metal chloride as the electrolyte molten salt, and the titanium ions added in the electrolyte molten salt or electrochemically dissolved in the anode are represented by Ti ²⁺ or Ti ³⁺ The form exists in the molten salt, and the original Ti ²⁺ in the molten salt and the Ti ²⁺ reduced by Ti ³⁺ undergo a disproportionation reaction in the molten salt This caused a lot of power loss and low electrolysis efficiency; moreover, the change of product morphology caused by the change of electrolysis composition would affect the quality of high-purity titanium.

Contents of the invention

In order to solve at least one of the technical problems in the prior art mentioned above, the present invention discloses a method for electrolytically refining high-purity titanium based on complex ion-based metastable high-temperature molten salt. In the metastable high-temperature molten salt, titanium ions It exists stably in the form of complex ions.

In the method for electrolytically refining high-purity titanium based on metastable high-temperature molten salt disclosed in some embodiments of the present invention, substances containing fluorine ions are added to the metastable high-temperature molten salt, and the added fluorine ions and titanium ions form complex ions.

In the method for electrolytically refining high-purity titanium based on metastable high-temperature molten salt based on complex ions disclosed in some embodiments of the present invention, the molar ratio of fluoride ions to titanium ions is set to 1:1-15:1.

According to some embodiments of the present invention, the metastable high-temperature molten salt electrolytic refining method for high-purity titanium based on complex ions, the substance containing fluorine ions includes alkali metal or alkaline earth metal fluoride.

Some embodiments of the present invention disclose a metastable high-temperature molten salt electrolytic refining method for high-purity titanium based on complex ions. The titanium ions include high-valent titanium ions and low-valent titanium ions.

According to some embodiments of the present invention, the metastable high-temperature molten salt electrolytic refining method for high-purity titanium based on complex ions, when the titanium ions are high-valent titanium ions, the high-valent titanium ions exist stably in the form of complex ions; When titanium ions are produced, the low-valent titanium ions are transformed into high-valent titanium ions, and then the high-valent titanium ions exist stably in the form of complex ions.

Some embodiments of the present invention disclose a method for electrolytically refining high-purity titanium based on metastable high-temperature molten salt based on complex ions. Titanium ions are provided by a titanium ion source, and the weight content of the titanium ion source in the metastable high-temperature molten salt is set. Between 2.0% and 15.0%.

Some embodiments of the present invention disclose a method for electrolytic refining of high-purity titanium based on metastable high-temperature molten salts based on complex ions. The metastable high-temperature molten salts include LiCl, MgCl ₂ , LiCl-KCl, LiCl-RbCl, LiCl-CsCl, MgCl ₂ -LiCl, MgCl ₂ -NaCl, MgCl ₂ -KCl, MgCl ₂ -RbCl, CaCl ₂ -LiCl, CaCl ₂ -NaCl, NaCl, KCl, RbCl, CsCl, CaCl ₂ , NaCl-KCl, NaCl-RbCl, NaCl -CsCl, MgCl ₂ -CsCl, CaCl ₂ -KCl, CaCl ₂ -RbCl.

Some embodiments of the present invention disclose a method for electrolytic refining of high-purity titanium based on metastable high-temperature molten salt based on complex ions. Before electrolysis, the metastable high-temperature molten salt is pre-melted and refined.

The method for electrolytically refining high-purity titanium based on metastable high-temperature molten salt based on complex ions disclosed in some embodiments of the present invention, the pre-melting and refining treatment specifically includes:

(i), pre-melted main body electrolyte;

(ii), adding other electrolytes that form eutectic salts with the host electrolyte;

(iii) At a temperature of 50°C above the eutectic temperature, the main electrolyte is fully mixed with other electrolytes to form a eutectic salt electrolyte;

(iv) Heating the eutectic salt electrolyte under vacuum, wherein the heating temperature is set between 100°C and 300°C, the degree of vacuum is set between 10 ^-2 and 10 ^-5 Pa, and the holding time is set between 6 and 12 hours between;

(v) In an argon atmosphere, heat the eutectic salt electrolyte to a temperature of 50°C above the melting point and the eutectic point respectively, perform secondary remelting, and keep for 24 hours;

(vi) Using hydrogen chloride gas to deoxidize the eutectic salt electrolyte, the treatment time is set between 1 and 3 hours.

The method disclosed by the invention changes the state of existence of titanium ions in the molten salt by changing the composition of the electrolyte and adding fluorine-containing substances as additives to form more stable complex ions and reduce the impact of the disproportionation reaction of titanium ions in the electrolysis process of molten salts , improve electrolysis efficiency, and obtain high-purity titanium by electrolytic refining in metastable molten salt, its purity can meet the requirements of 4N5-5N, and the electrolysis efficiency is greater than 90%.

Description of drawings

Figure 1 Schematic diagram of the principle of metastable high-temperature molten salt electrolytic refining of high-purity titanium based on complex ions

Fig. 2 sample figure obtained from embodiment 1-3 disclosed by the present invention

Detailed ways

The word "embodiment" is used here exclusively, and any embodiment described as "exemplary" is not necessarily to be construed as superior or better than other embodiments. In the performance index test in the embodiment of this method, unless otherwise specified, conventional test methods in this field are adopted. It should be understood that the terminology described in the present invention is only used to describe a specific embodiment, and is not used to limit the disclosed content of the present invention.

Unless otherwise specified, the technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs; as other unspecified raw materials, reagents, test methods and technical means in the present invention are all Refers to the raw materials and reagents commonly used by those of ordinary skill in the art, as well as the commonly used experimental methods and technical means; the molten salt electrolytes mentioned in the disclosure of the present invention include but are not limited to elemental electrolytes and eutectic salt electrolytes, usually elemental electrolytes refer to A single substance electrolyte, such as LiCl; eutectic salt electrolyte refers to the mixture of two or more simple electrolytes that can form a mixed electrolyte with a eutectic point. In the eutectic salt with a eutectic point, the proportion of the components is constant For example, the eutectic salt electrolyte LiCl-KCl formed by LiCl and KCl, wherein the molar ratio of the two is 0.59:0.41; the main electrolyte mentioned in the disclosure of the present invention usually refers to the main component in the eutectic salt, and other electrolytes, then Refers to other components in the eutectic salt except the main electrolyte; high-valent titanium ions usually refer to trivalent titanium ions Ti ³⁺ , and low-valent titanium ions usually refer to divalent titanium ions Ti ²⁺ ; substances containing fluoride ions, usually Refers to substances that can release F ^- fluoride ions in metastable high-temperature molten salts, including but not limited to sodium fluoride and potassium fluoride; titanium ion sources usually refer to substances that can release titanium ions in high-temperature molten salts, including But not limited to titanium dichloride and titanium trichloride; the molar content usually refers to mole/mole, and the weight content usually refers to weight/weight.

The terms "substantially" and "approximately" are used in this disclosure to describe small fluctuations. For example, they may refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ± 0.1%, if less than or equal to ±0.05%. Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. Such a range format is used merely for convenience and brevity and, therefore, should be construed flexibly to include not only the values explicitly recited as the boundaries of the range, but also all individual values or subranges subsumed within the range. For example, a numerical range of "1% to 5%" should be interpreted to include not only the explicitly recited value of 1% to 5%, but also include individual values and subranges within the indicated range. Accordingly, individual values such as 2%, 3.5% and 4%, and subranges such as 1% to 3%, 2% to 4% and 3% to 5% etc. are included in this numerical range. The same principle applies to ranges reciting only one numerical value. Moreover, such an interpretation applies regardless of the breadth of the range or the characteristics described.

In this disclosure, including the claims, all conjunctions such as "comprises," "comprises," "with," "has," "containing," "relates to," "contains," etc., are to be construed as open-ended means "including but not limited to". Only the conjunctions "consisting of" and "consisting essentially of" should be closed or semi-closed conjunctions.

In order to better illustrate the contents of the present invention, numerous specific details are given in the following specific examples. It will be understood by those skilled in the art that the present invention may be practiced without certain of the specific details. In the embodiments, some methods, means, instruments, equipment, raw material compositions, molecular structures, etc. that are well known to those skilled in the art are not described in detail, so as to highlight the gist of the present invention.

In some embodiments disclosed in the present invention, substances containing fluoride ions are added to the metastable high-temperature molten salt, and the titanium ions in the titanium ion source form complex ions with the added fluoride ions. In some embodiments, the titanium ion source ion is high-valent titanium ion Ti ³⁺ , and the substance containing fluoride ion is added to the molten salt electrolyte as an additive, which can effectively complex the high-valent titanium ion Ti ³⁺ in the molten salt to form a complex ion:

TiCl _6-i F _i ^3- , where x is an integer between 1-6

The stable existence of the complex ions makes the concentration of Ti ³⁺ ions in the molten salt electrolyte account for the largest proportion of the total concentration of titanium ions, and the average valence state of titanium ions in the molten salt at this time is greater than 2.8. Then, the three-electron one-step reduction from Ti ³⁺ to titanium metal can be achieved during the electrochemical reduction process.

In some embodiments, the source ions of titanium ions are low-valent titanium ions Ti ²⁺ . In the molten electrolyte, the low-valent titanium ions Ti ²⁺ undergo disproportionation reactions and coexist with high-valent titanium ions Ti ³⁺ , forming the following formula: Balanced state:

Substances containing fluoride ions are added to the molten salt electrolyte as additives, which can effectively complex the high-valent titanium ions Ti ³⁺ in the molten salt to form complex ions. The stable existence of the complex ions makes the low-valent titanium in the molten salt electrolyte The ion concentration of Ti ²⁺ decreases, and the high-valent titanium ion Ti ³⁺ accounts for the largest proportion of the total concentration of titanium ions, and then the three-electron one-step reduction from Ti ³⁺ to metal titanium can be realized in the process of electrochemical reduction.

The commonly added fluoride ion-containing substances include alkali metal or alkaline earth metal fluorides, for example, sodium fluoride, potassium fluoride and the like. Sodium fluoride, potassium fluoride, etc. release fluoride ions in the electrolyte molten salt. In some embodiments of the present invention, the molar ratio of the substance containing fluoride ions to the source of titanium ions is 1:1 to 15:1; as a more preferred embodiment, it can be selected as 2:1 to 12:1, and as a further preferred In an embodiment, it can be selected as 3:1 to 10:1.

Usually titanium ion sources include substances containing low-valent titanium and substances containing high-valent titanium; usually low-valent titanium includes Ti ²⁺ , as the source of low-valent titanium ions can choose TiCl ₂ and TiCl ₃ mixed salt; usually high-valent titanium includes Ti ³⁺ , TiCl ₃ can be selected as the source of high-valent titanium ions. Usually, TiCl ₂ and electrolyte or eutectic salt electrolyte are made into a molten salt containing low-valent titanium ions Ti ²⁺ , as an optional implementation of adding low-valent titanium ions and titanium ion sources.

In some embodiments, the metastable high-temperature molten salt used includes LiCl, MgCl ₂ , LiCl-KCl, LiCl-RbCl, LiCl-CsCl, LiCl-NaCl, KCl-CsCl, MgCl ₂ -LiCl, MgCl ₂ -NaCl, MgCl ₂ -KCl, MgCl ₂ -RbCl, CaCl ₂ -LiCl, CaCl ₂ -NaCl, NaCl, KCl, RbCl, CsCl, CaCl ₂ , NaCl-KCl, NaCl-RbCl, NaCl-CsCl, MgCl ₂ -CsCl, CaCl ₂ -KCl, CaCl ₂ -RbCl, CaCl ₂ -CsCl. The composition and ratio of the above-mentioned eutectic salt electrolyte are listed in Table 1.

Table 1 Eutectic salt electrolyte composition and its molar ratio

In some embodiments of the present invention, in metastable high-temperature molten salt electrolytic refining of high-purity titanium based on complex ions, the metastable molten salt is subjected to pre-melting and refining treatment before electrolysis. Specifically, the pre-melting and refining treatment includes the following:

(i), pre-melted main body electrolyte;

(ii), adding other electrolytes that form eutectic salts with the host electrolyte;

(iii) At a temperature of 50°C above the eutectic temperature, the main electrolyte is fully mixed with other electrolytes to form a eutectic salt electrolyte;

(iv) Heating the eutectic salt electrolyte under vacuum, wherein the heating temperature is set between 100°C and 300°C, the degree of vacuum is set between 10 ^-2 and 10 ^-5 Pa, and the holding time is set between 6 and 12 hours Between; that is, the removal of water present in the eutectic salt electrolyte under vacuum ambient conditions;

(v) In an argon atmosphere, heat the eutectic salt electrolyte to a temperature of 50°C above the melting point and the eutectic point, perform secondary remelting, and keep for 24 hours; usually after removing the water in the eutectic salt electrolyte, Fill high-purity argon into a vacuum environment, and carry out secondary remelting under the protection of argon at a temperature 50°C above the melting point temperature of the monomer electrolyte and the eutectic point temperature of the eutectic salt electrolyte;

(vi) Use hydrogen chloride gas to deoxidize the eutectic salt electrolyte, and the treatment time is set between 1 and 3 hours; usually, the eutectic salt electrolyte that has been remelted twice is treated in the presence of hydrogen chloride gas to remove Oxygen in it. Usually, after the deoxygenation is completed, it is necessary to replace the hydrogen chloride gas with an inert gas, such as argon, so as to remove the hydrogen chloride gas.

Generally, (i), (ii) and (iii) in the premelting and refining treatment can be collectively referred to as premelting treatment, and (iv), (v), and (vi) can be collectively referred to as refining treatment. As some embodiments, the pre-melting treatment and the refining treatment can be performed separately. In the process of premelting and refining, if a single molten salt is used as the electrolyte, the main electrolyte is the simple electrolyte, and the steps involving other electrolytes are omitted.

In some embodiments of the present invention, in the method of electrolytically refining high-purity titanium using low-valent titanium as a source of titanium ions, after pre-melting and refining the eutectic salt electrolyte, a substance containing low-valent titanium ions is added to the eutectic salt electrolyte , and then add fluorine-containing ions into the eutectic salt electrolyte, so that the ions in the molten salt are mixed evenly, and the low-valent titanium ions Ti ²⁺ are converted into high-valent titanium ions Ti ³⁺ , and then stabilized in the form of Ti ³⁺ complex ions In the electrolyte molten salt, a molten salt electrolyte with an absolute ratio of Ti ³⁺ concentration is obtained.

In some embodiments of the present invention, in the method of electrolytically refining high-purity titanium using high-valent titanium as a source of titanium ions, substances containing fluorine ions are added to the eutectic salt electrolyte, and pre-melting and refining treatment is performed. At a crystal temperature of 50°C, add substances containing high-valent titanium ions, such as powdered titanium trichloride, to the eutectic salt electrolyte to mix the ions in the molten salt, and high-valent titanium ions Ti ³⁺ to form complex ions The form of is stable in the molten salt electrolyte, and the molten salt electrolyte with the absolute ratio of Ti ³⁺ concentration is obtained.

Titanium complex ions, which exist stably in molten electrolyte, participate in the electrolytic reaction process of electrolytic refining of high-purity titanium. As shown in Figure 1, titanium complex ions are gradually deposited on the cathode during constant current electrolysis to obtain high-purity titanium. The metal, which is gradually consumed by the anode, dissolves in the electrolyte molten salt in the form of titanium ions to form titanium complex ions to supplement the titanium complex ions consumed in the electrolyte.

In the disclosure of the present invention, the electrolytic efficiency of metastable high-temperature molten salt electrolytic refining of high-purity titanium is calculated according to formula (1). The electrolytic efficiency calculation formula (1) is:

In the formula (1): _ma is the mass of the electrolysis product actually obtained, and m _t is the theoretical product mass calculated according to Faraday's law, which is calculated according to the following formula (2):

In the formula (2): I is the actual electrolysis current, t is the actual electrolysis time, M _Ti is the atomic mass of metal titanium, Z is the valence state of the discharge ion, and F is the Faraday constant.

In some embodiments of the present invention, the electrolytic refining of high-purity titanium in metastable high-temperature molten salt is carried out according to the following methods, specifically including:

Pre-melted and refined eutectic salt electrolyte;

Place the pre-melted and refined eutectic salt electrolyte in an alumina crucible, add a titanium ion source to obtain a pre-mixture; heat the mixture to the melting temperature, for example, 750°C under the protection of argon, to fully mix the ions Uniform, to obtain a preliminary molten salt with homogeneous titanium ions; add the fluoride ion source to the preliminary molten salt in proportion, and wait for the fluorine ions to fully complex with the titanium ions, and maintain the set time at the working temperature, usually the set time Between 12 and 24 hours; cool down;

Use two anodes and one cathode as the electrolysis electrodes, arrange the electrode distance reasonably, place the electrodes in the furnace body, and ensure that the furnace body is airtight and vacuumize; clean the furnace chamber with high-purity argon at the set temperature, and place it in the normal position. For example, the furnace chamber can be cleaned at 300°C; after the temperature rises to the melting temperature, keep warm, slowly put the electrode into the molten salt; perform constant current electrolysis at a constant current density; usually the constant current is set at 0.1 to 1.5 A/ ^cm2 ; after electrolysis, place the electrode above the molten salt to drain the salt contained in the product; open the furnace to take out the cathode, and place the cathode plate deposited with high-purity titanium products in deionized water for ultrasonic cleaning; Dry the washed cathode product in a vacuum oven to obtain high-purity titanium metal. For example, the drying temperature can be set at 50°C.

Example 1

According to the disclosed method of the present invention, pre-melt and refine the NaCl-KCl (0.5:0.5) eutectic salt electrolyte;

Place the NaCl-KCl eutectic salt after pre-melting and refining treatment in an alumina crucible, add NaCl-KCl-TiCl _molten salt containing low-valent titanium ions to the crucible, so that the content of _TiCl in the molten salt is 4.5%; the mixture is heated to 750°C under the protection of argon, so that the ions are fully mixed to obtain a preliminary molten salt with homogeneous titanium ions; KF is added to the preliminary molten salt in proportion as the fluoride ion source, In Example 1, the molar ratio of fluoride ions to low-valent titanium ions is 2.0. After the fluorine ions and titanium ions are fully complexed, keep at the working temperature for 24 hours and cool down;

Use two anodes and one cathode as electrolytic electrodes, reasonably arrange the electrode distance, place the electrodes in the furnace body, and ensure that the furnace body is airtight and vacuumized; clean the furnace cavity with high-purity argon at 300 ° C, and set positive pressure protection ; After the temperature rises to 750°C, keep it warm for 2 hours, then slowly put the electrode into the molten salt; carry out constant current electrolysis under the condition of a current density of 0.5A/cm ² ; after the electrolysis, place the electrode above the molten salt for 3~ 5cm, drain the salt in the product; open the furnace to take out the cathode, and place the cathode plate deposited with high-purity titanium products in deionized water for ultrasonic cleaning; put the washed cathode product in a vacuum oven at 50°C and dry it Dry to obtain high-purity titanium metal.

Fig. 2(a) is the sample diagram of the high-purity titanium obtained in Example 1. It can be seen that high-purity titanium is granular crystal with obvious metallic luster.

According to the formulas (1) and (2), the electrolysis efficiency of the present embodiment 1 is calculated to be about 91.7%, wherein the valence state of the discharged ions is calculated as 3.

Example 2

According to the disclosed method of the present invention, pre-melt and refine the NaCl-KCl (0.5:0.5) eutectic salt electrolyte;

Place the premelted and refined NaCl-KCl eutectic salt in an alumina crucible, add NaCl-KCl-TiCl ₂ molten salt containing low-valent titanium ions to the crucible, so that the content of TiCl ₂ in the molten salt It is 2.5%; the mixture is heated to 750°C under the protection of argon, so that the ions are fully mixed and uniform, and a preliminary molten salt with homogeneous titanium ions is obtained; KF is added to the preliminary molten salt in proportion as the fluoride ion source , The molar ratio of fluoride ions to low-valent titanium ions in Example 2 is 4.0. After the fluorine ions and titanium ions are fully complexed, keep at the working temperature for 24 hours and cool down;

Use two anodes and one cathode as electrolytic electrodes, reasonably arrange the electrode distance, place the electrodes in the furnace body, and ensure that the furnace body is airtight and vacuumized; clean the furnace cavity with high-purity argon at 300 ° C, and set positive pressure protection ; After the temperature rises to 750°C, keep it warm for 2 hours, slowly put the electrode into the molten salt; carry out constant current electrolysis under the condition of a current density of 0.5A/cm ² ; after the electrolysis, place the electrode 5cm above the molten salt , drain the salt in the product; open the furnace to take out the cathode, and place the cathode plate deposited with high-purity titanium products in deionized water for ultrasonic cleaning; put the washed cathode product in a vacuum oven at 50°C and dry it. Obtain high-purity titanium metal.

Fig. 2(b) is the sample diagram of the high-purity titanium obtained in Example 2. It can be seen that high-purity titanium is mainly granular crystals, with a small amount of powdered titanium.

According to the formulas (1) and (2), the electrolysis efficiency of the present embodiment 2 is about 93.1%, and the valence state of the discharged ions is calculated as 3.

Example 3

According to the disclosed method of the present invention, pre-melt and refine the NaCl-KCl (0.5:0.5) eutectic salt electrolyte;

The NaCl-KCl eutectic salt after the pre-melting and refining treatment is placed in an alumina crucible, and _TiCl is added to the crucible so that the content of _TiCl in the molten salt is 4.0%; the mixture is heated up to 750°C, mix the ions fully and evenly, and let stand for about 6 hours to obtain a preliminary molten salt with homogeneous titanium ions; NaF is added to the preliminary molten salt in proportion as the source of fluoride ions. In Example 3, the fluoride ion The molar ratio to high-valent titanium ions is 6.0. After the fluorine ions and titanium ions are fully complexed, keep at the working temperature for 24 hours and cool down;

Use two anodes and one cathode as electrolytic electrodes, reasonably arrange the electrode distance, place the electrodes in the furnace body, and ensure that the furnace body is airtight and vacuumized; clean the furnace cavity with high-purity argon at 300 ° C, and set positive pressure protection ; After the temperature rises to 750°C, keep it warm for 2 hours, slowly put the electrode into the molten salt; carry out constant current electrolysis under the condition of a current density of 0.5A/cm ² ; after the electrolysis, place the electrode 5cm above the molten salt , drain the salt in the product; open the furnace to take out the cathode, and place the cathode plate deposited with high-purity titanium products in deionized water for ultrasonic cleaning; put the washed cathode product in a vacuum oven at 50°C and dry it. Obtain high-purity titanium metal.

Fig. 2(c) is the sample diagram of the high-purity titanium sample obtained in Example 3. It can be seen that high-purity titanium is a granular crystal with a relatively fine and uniform particle size and a metallic luster.

According to the formula (1), (2), the electrolysis efficiency of the present embodiment 3 is calculated to be about 94.6%, wherein the valence state of the discharged ions is calculated as 3.

The method disclosed in the present invention changes the state of titanium ions in the molten salt by adding fluorine-containing additives to form more stable complex ions, reduces the impact of the disproportionation reaction of titanium ions in the molten salt electrolysis process, and improves the electrolysis efficiency. The high-purity titanium obtained by electrolytic refining in steady-state molten salt can meet the requirements of 4N5-5N in purity, and the electrolysis efficiency is greater than 90%.

The technical solutions disclosed in the present invention and the technical details disclosed in the embodiments are only exemplary illustrations of the concept of the present invention, and do not constitute a limitation to the present invention. Any non-creative changes to the technical details disclosed in the present invention are consistent The present invention has the same inventive spirit and is within the protection scope of the claims of the present invention.

Claims (10)

1. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium based on complex ion, which is characterized in that described metastable In state high-temperature molten salt, titanium ion exists with the form stable of complex ion.

2. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 1 based on complex ion, It is characterized in that, the substance of fluoride ion is added in the metastable state high-temperature molten salt, and the fluorine ion is formed with the titanium ion Complex ion.

3. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 2 based on complex ion, It is characterized in that, the molar ratio of the fluorine ion and the titanium ion is set as 1:1~15:1.

4. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 3 based on complex ion, It is characterized in that, the substance of the fluoride ion includes alkali or alkaline earth metal fluoride.

5. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 1 based on complex ion, It is characterized in that, the titanium ion includes high price titanium ion and low valence titanium ion.

6. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 5 based on complex ion, It is characterized in that, when the titanium ion is high price titanium ion, high price titanium ion exists with the form stable of complex ion；The titanium from When son is low valence titanium ion, low valence titanium ion is converted into high price titanium ion, and then high price titanium ion is steady in the form of complex ion It is fixed to exist.

7. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 1 based on complex ion, It is characterized in that, the titanium ion is provided by titanium ion source, and weight of the titanium ion source in the metastable state high-temperature molten salt contains Amount is arranged between 2.0%~15.0%.

8. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 1 based on complex ion, It is characterized in that, the metastable state high-temperature molten salt includes：LiCl、MgCl₂、LiCl-KCl、LiCl-RbCl、LiCl-CsCl、MgCl₂- LiCl、MgCl₂-NaCl、MgCl₂-KCl、MgCl₂-RbCl、CaCl₂-LiCl、CaCl₂-NaCl、NaCl、KCl、RbCl、CsCl、 CaCl₂、NaCl-KCl、NaCl-RbCl、NaCl-CsCl、MgCl₂-CsCl、CaCl₂-KCl、CaCl₂-RbCl。

9. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 1 based on complex ion, It is characterized in that, electrolysis foregoing description metastable state high-temperature molten salt passes through fritting refinement treatment.

10. the method for the metastable state high temperature fused salt electrolysis refining high purity titanium according to claim 9 based on complex ion, It is characterized in that, the fritting refinement treatment includes：

(i), fritting bulk electrolyte；

(ii), other electrolyte that eutectic salts are formed with bulk electrolyte are added；

(iii), on eutectic temperature at a temperature of 50 DEG C, bulk electrolyte is made to be sufficiently mixed, be formed altogether with other electrolyte Brilliant salt electrolyte；

(iv), eutectic salt electrolyte is heated under vacuum, wherein heating temperature is arranged between 100~300 DEG C, vacuum degree It is arranged 10^-2~10^-5Between Pa, the retention time was arranged between 6~12 hours；

(v), eutectic salt electrolyte is separately heated to fusing point in argon atmospher, 50 DEG C of temperature on eutectic point, carried out secondary Remelting is kept for 24 hours；

(vi), deoxidation treatment is carried out to eutectic salt electrolyte using hydrogen chloride gas, the deoxidation treatment time was arranged at 1~3 hour Between.