An apparatus and method for preparing high-purity titanium by in-situ chlorination-cyclic electrolysis

Abstract

The present invention provides a device and method for preparing high-purity titanium by in-situ chlorination-cyclic electrolysis, belonging to the field of titanium production by electrolysis. The device includes a chlorinator, a fractionator, an electrolytic cell and a low-valent titanium reactor, and can realize electrolysis in a molten salt electrolyte containing a single Ti 3+ or Ti 2+ . During electrolysis, the Cl2 generated on the graphite anode enters the chlorinator; the chlorination raw material is sprayed into the chlorinator from the top nozzle for chlorination reaction, and the required reaction temperature is provided by the radiant heat of the molten salt electrolyte and the waste heat of the electrolytic cell; the gaseous product after the reaction is fractionated by the fractionator to separate out TiCl4 and sent into the low-valent titanium reactor and bubbles out to react with excessive sponge titanium; Ti 3+ or Ti 2+ in the molten salt electrolyte is discharged and deposited on the cathode in one step to form high-purity titanium. The present invention completes the cycle of chlorination and electrolysis in one electrolytic cell, with higher efficiency, energy consumption saved, the adverse effects brought about by the coexistence of multi-valent titanium ions in the molten salt electrolysis process eliminated, and the benefit improved.

Description

Technical Field

[0001] The invention relates to a device and a method for preparing high-purity titanium by in-situ chlorination-circulation electrolysis, belonging to the field of producing metallic titanium by electrolysis. Background Art

[0002] There are currently two main methods for producing high-purity titanium in industry, the Kroll process and the molten salt electrolysis process. Among them, the Kroll process requires very high-purity TiCl4 and Mg as raw materials when producing high-purity titanium, and TiCl4 comes from the high-temperature carbon chlorination of TiO2, and Mg comes from the molten salt electrolysis of MgCl2, so the entire process is relatively complicated, resulting in its high cost. The molten salt electrolysis method generally uses low-purity sponge titanium produced by the Kroll process as the anode raw material, and prepares low-oxygen high-purity titanium by electrolytic refining (such as patents CN104928722A, CN102230193A, CN104928719A, etc.), although it has the advantages of being environmentally friendly and not generating waste gas and waste, but because the production of sponge titanium raw materials is still inseparable from the Kroll process, it cannot solve the problem of complex production process and high cost of high-purity titanium.

[0003] TiCl4 electrolysis was once considered the most likely method to replace the Klauer process for the industrial electrolytic production of high-purity titanium, because direct use of TiCl4 electrolysis can save the Mg thermal reduction and MgCl2 electrolysis steps in the Klauer process, with lower energy consumption and simpler processes. However, in practical applications, this method needs to focus on solving three major problems: 1. Low-temperature, efficient and rapid chlorination preparation of TiCl4 to reduce raw material costs; 2. TiCl4 has a very low solubility in the chloride molten salt system and is not suitable for large-scale industrial electrolytic production. It must be converted into low-valent titanium (Ti) with a higher solubility in the molten salt system. 3+ or Ti 2+ ). 3. Titanium exists in multiple valence states in molten salt. In the electrolysis process, the incomplete discharge of titanium ions at the cathode and the disproportionation reaction between titanium ions in different valence states reduce the current efficiency of the entire electrolysis process. Especially for problem 3, no effective solution has been proposed in the existing relevant patents and literature.

[0004] In the aspect of low-temperature, highly efficient and rapid chlorination preparation of TiCl4. In patents CN105819500A and CN108529668A, a "low-temperature selective chlorination to produce TiCl4" process and a low-temperature chlorination furnace are mentioned. Using titanium carbide (TiC) or carbide slag as raw materials, TiCl4 is produced by low-temperature boiling chlorination technology at 400 - 600 °C. Patent CN114426304A discloses a method for low-temperature chlorination of titanium from titanium carbide slag by fluidization. Using titanium carbide slag with a titanium carbide or titanium oxycarbide mass content of 10 - 40% as the raw material, titanium tetrachloride is prepared in a fluidized bed reactor at 350 - 600 °C by fluidized low-temperature chlorination technology, and the average residence time of the material is 10 - 90 min. Patent CN105197989A discloses a flash suspension chlorination method for titanium-containing raw materials. The titanium-containing raw materials with a particle size less than 40 mesh (TiO2 content > 70%) are sprayed into the reaction chamber using chlorine gas as the carrier gas and react under the conditions of a reducing atmosphere at 600 - 800 °C and a negative pressure of 20 - 40 kPa. Although the above processes achieve low-temperature chlorination to prepare TiCl4, the chlorine gas used needs to be produced separately, resulting in additional cost increases.

[0005] In the aspect of molten salt electrolysis of TiCl4 to prepare high-purity titanium. Patent CN103014775A discloses a method and device for producing titanium by molten salt electrolysis. Using a metal magnesium anode and a metal titanium cathode in a mixed molten salt of sodium chloride and potassium chloride, titanium tetrachloride is electrolyzed to produce magnesium chloride and titanium. In this patent, the electrolytic anode gas Cl2 reacts with the metal magnesium anode to form a by-product magnesium chloride. Not only is the precious chlorine gas resource not fully utilized, but the mixing of magnesium chloride with the supporting electrolyte NaCl-KCl is bound to cause changes in the electrolyte composition and properties, thus affecting the stable operation of the electrolysis process; in addition, the outlet of the TiCl4 feed pipe designed in this patent is directly opposite to the cathode, which is bound to cause a contact reaction between TiCl4 and the cathode-deposited Ti, thus seriously reducing the yield; moreover, this patent does not consider the problem of low solubility of TiCl4 in chloride molten salts and the adverse effects brought by the coexistence of polyvalent titanium ions, and the electrolysis raw material TiCl4 also needs to be prepared separately.

[0006] Patent CN101519789A provides a method for producing metallic titanium by titanium cycle molten salt electrolysis, which includes two processes: A. Reducing titanium tetrachloride to at least one of titanium trichloride and titanium dichloride with metallic titanium in a chloride molten salt; B. Electrolyzing at least one of the produced titanium trichloride and titanium dichloride into titanium in the said chloride molten salt. Process A solves the problem of low solubility of TiCl4 in chloride molten salts; although process B to some extent realizes the adverse effects brought by the coexistence of polyvalent titanium ions, it fails to propose an effective control scheme. As is well known, without additional intervention measures, the reaction between TiCl4 and metallic titanium in chloride molten salts can only produce Ti 3+ and Ti 2+mixture, making it difficult to obtain a single Ti 3+ or Ti 2+ , so if the operation is carried out according to the method disclosed in this patent, it is impossible to completely avoid the incomplete cathode discharge and disproportionation reaction caused by the coexistence of multiple low-valent titanium ions. In addition, although this patent proposes to collect the chlorine gas evolved at the anode, it is only recycled as a by-product, and a true "circulating molten salt electrolysis" process has not been achieved. The electrolysis raw material TiCl4 still needs to be separately prepared.

[0007] Patent US4165262 discloses a method for electrolytic refining of titanium. TiCl4 is introduced into a KCl-LiCl molten salt for electrolysis. Metallic titanium is deposited on the metal cathode, and chlorine gas is generated on the carbon anode. To prevent the anode gas from reaching the cathode, a porous diaphragm is installed between the cathode and anode. The TiCl4 feeding device is combined with the cathode chamber to supply raw materials to the molten salt electrolyte in the cathode chamber. To reduce the disproportionation reaction between TiCl4 and the cathode product, this patent designs the feeding device far away from the cathode, resulting in low space utilization of the electrolytic cell and being unable to avoid the adverse effects brought by the coexistence of multi-valent titanium ions. In addition, this patent fails to consider the problem of low solubility of TiCl4 in chloride molten salts, and the treatment of the anode gas chlorine is only simple collection. The electrolysis raw material TiCl4 still needs to be separately prepared.

[0008] Patent US6024847 discloses a device and method for preparing titanium crystals and titanium. The Korll process is combined with the molten salt electrolytic refining process. After using metallic Mg (Kroll process) or Na (Hunter process) to reduce TiCl4 in the container for producing titanium sponge to prepare titanium sponge, the prepared titanium sponge is used as the anode to carry out in-situ molten salt electrolysis of titanium in the same container to produce high-purity titanium crystals. This method has no essential difference from the molten salt electrolysis method using titanium sponge as the anode raw material. Its chlorination treatment of the molten salt is to convert TiCl4 into TiCl3 and TiCl2 in order to obtain an electrolyte with a certain titanium ion concentration, rather than to solve the problem of low solubility of TiCl4 in chloride molten salts, and the problem brought by the coexistence of multi-valent titanium ions has not been solved either. In addition, the chlorine cycle in this method still needs to return to the Kroll process, and TiCl4 still needs to be separately prepared.

[0009] Based on the above-mentioned literature, it can be found that the preparation of TiCl4 and electrolysis are two independent processes, and the overall cost is still relatively high. Moreover, no solution has been proposed to inhibit the adverse effects brought about by the coexistence of multi-valent titanium ions. Patent CN103290433B discloses a device and process for preparing pure titanium by molten salt electrolysis in a double electrolytic cell. In the first electrolytic cell, Cl2 generated at the anode chlorinates the mixture of TiO2 and C located at the bottom of the electrolytic cell to obtain TiCl4, and Ca generated at the cathode reduces TiCl4 to TiClx (x = 2, 3); TiClx is introduced into the second electrolytic cell for electrolysis, and pure titanium is obtained at the cathode, and Cl2 generated at the anode is recycled to the bottom of the first electrolytic cell to react with the mixture of TiO2 and C. This patent combines the preparation of TiCl4 and the electrolysis process, and realizes the recycling of Cl2 while preparing pure titanium. However, in the first electrolytic cell, using Ca to react with TiCl4 to generate low-valent titanium solves the problem of low solubility of TiCl4, but the essence of the chlorination reaction is still the traditional TiO2 carbon chlorination process, which requires a relatively high temperature and does not solve the problem of low-temperature, high-efficiency and rapid chlorination preparation of TiCl4; in the second electrolytic cell, TiClx (x = 2, 3) still has the coexistence of multi-valent titanium ions, so the resulting adverse effects cannot be avoided either. Patent CN109267100A discloses a device and method for preparing pure titanium by electrolysis-chlorination-electrolysis. Taking advantage of the advantages of TiCxOy / TiCxOyNz, such as lower chlorination temperature, faster reaction rate and higher chlorination efficiency compared with TiO2 and TiC, the three processes of chlorine preparation, low-temperature chlorination of TiCxOy / TiCxOyNz and electrolysis of TiCl4 are completed in the same device; adopting a double electrolytic cell design to separate the low-temperature chlorination of TiCxOy / TiCxOyNz from the electrolysis of TiCl4 is beneficial to the preparation of high-purity titanium and realizes the internal recycling of Cl2 generated at the two anodes. However, there are the following problems with this device and method: 1. The chlorination of TiCxOy / TiCxOyNz adopts an approximate boiling chlorination method, and the characteristics of fast reaction rate of TiCxOy / TiCxOyNz chlorination reaction are not fully utilized; 2. The double electrolytic cell design makes the process operation slightly complicated, and Cl2 is generated at the anodes of both electrolytic cells, with overlapping functions; 3. The generated TiCl4 is directly introduced to the cathode to react to generate low-valent titanium ions and then deposited as pure titanium. Although the problem of low solubility of TiCl4 is solved, the adverse effects brought about by the coexistence of multi-valent titanium ions are still not eliminated.

[0010] The key to eliminating the adverse effects brought about by the coexistence of multi-valent titanium ions lies in using a molten salt electrolyte of single-valent titanium ions (Ti 3+ or Ti 2+ ). Although many scholars have studied the equilibrium relationship (equilibrium constant) between different titanium ions, no control scheme for the composition of a molten salt electrolyte of single-valent titanium ions has been proposed so far.

[0011] The above content is not all prior art, and some are the research results of the inventors of the present invention. Summary of the Invention

[0012] The object of the present invention is to provide a device and method for preparing high-purity titanium by in-situ chlorination-circulating electrolysis in view of the deficiencies of the above-mentioned existing technologies. Compared with the existing technologies, the device and method of the present invention have a simpler structure, a more convenient process, a higher chlorination efficiency, can more effectively save raw materials and preparation costs, and in particular, a control scheme for the composition of molten salt electrolyte of single-valence titanium ions is proposed to eliminate the adverse effects brought about by the coexistence of multi-valence titanium ions during the molten salt electrolysis process.

[0013] In the first aspect, a device for preparing high-purity titanium by in-situ chlorination-circulating electrolysis is provided, including:

[0014] An electrolytic cell, which is provided with an anode, a cathode and a molten salt electrolyte containing single Ti 3+ or Ti 2+ ;

[0015] A chlorinator, which is located above the liquid level of the molten salt electrolyte in the electrolytic cell and above the anode, so as to heat the chlorinator by using the radiant heat of the molten salt electrolyte and the waste heat of the electrolytic cell, and utilize the anode gas Cl2; the chlorinator includes a nozzle located at the top for introducing chlorination raw materials;

[0016] A fractionator, which is located outside the electrolytic cell and is communicated with the upper part of the chlorinator, and is used for fractionating the mixed gas coming out of the chlorinator;

[0017] A low-valent titanium reactor, which is arranged at the bottom of the electrolytic cell and close to the cathode, and includes a gas inlet at the bottom, a plurality of through-hole outlets at the top, and sponge titanium above the top, and the gas inlet is communicated with the outlet of the fractionator; it is used to convert TiCl4 coming out of the fractionator into Ti 3+ or Ti 2+ in one of them to supplement the titanium source in the molten salt electrolyte at any time.

[0018] It can be understood that the electrolytic cell also has a carrier gas outlet, which is located on the side of the top.

[0019] The sponge titanium is preferably in excess to make TiCl4 react fully.

[0020] Preferably, the device further includes:

[0021] An anode cover, which is arranged at the bottom of the chlorinator and communicated, and is located above the anode in the electrolytic cell and covers at least 1 / 4 of the anode height, so as to collect the anode gas Cl2 in time and fully.

[0022] More preferably, the lower part of the anode hood is in the shape of an open trumpet, and its inner diameter at the lower part increases successively from top to bottom.

[0023] Preferably, the chlorinator further includes: a porous filter sheet, which is laid flat inside the chlorinator and divides the chlorinator into upper and lower chambers for filtering the anode gas Cl2.

[0024] Preferably in the present invention, an air inlet Ⅰ is arranged between the bottom of the chlorinator and the porous filter sheet, and the air inlet Ⅰ is opened on the side wall of the chlorinator for introducing a carrier gas to load the anode gas Cl2 into the chlorinator after filtering through the porous filter sheet.

[0025] Preferably, the upper surface of the low-valent titanium reactor is concave and has a number of through-hole outlets, so that the material emerges from the through-hole outlets in a bubbling manner. Preferably, the angle between the outer tangent of the concave shape and the horizontal line is 1-10 °C.

[0026] Preferably, the concave shape is a V shape.

[0027] More preferably, among the number of through-hole outlets at the top of the low-valent titanium reactor, one is located in the middle of the top, and the remaining through-hole outlets are arranged at intervals along the circumferential direction.

[0028] Preferably, the gas inlet of the low-valent titanium reactor is connected to the gas outlet of the fractionator through a connecting pipe, and an air inlet Ⅲ is connected to the connecting pipe for introducing a carrier gas to transport TiCl4 into the low-valent titanium reactor.

[0029] Preferably, the device further includes:

[0030] A partition plate, which is arranged in the electrolytic cell and located between the anode and the cathode and extends upward along the liquid level of the molten salt electrolyte. The partition plate is provided with partition plate through-holes; preferably, the cathode and the low-valent titanium reactor are located on the same side of the partition plate.

[0031] Preferably, the device further includes a heating and temperature control system, which is arranged outside the electrolytic cell for controlling the temperature inside the electrolytic cell.

[0032] In a second aspect, the present invention provides a method for in-situ chlorination-circulation electrolysis to prepare high-purity titanium, which is carried out by using the device described in the first aspect, and the method includes the following steps:

[0033] S1. Prepare in advance a solution containing a single Ti 3+ or Ti 2+The molten salt electrolyte is charged into the electrolytic cell; the anodic gas Cl2 electrolytically evolved enters the chlorinator; meanwhile, the pre-crushed chlorination raw material is sprayed into the chlorinator through a nozzle and reacts with Cl2 to generate TiCl4, obtaining a mixed gas containing TiCl4;

[0034] S2. The mixed gas enters the fractionator from the chlorinator. After fractionation, the CO or CO+N2 therein is discharged from the gas outlet 1 above the fractionator, and the TiCl4 therein is condensed into a liquid state and then transported to the low-valent titanium reactor located at the bottom of the electrolytic cell;

[0035] S3. The TiCl4 entering the low-valent titanium reactor emerges from the through-hole outlet of the low-valent titanium reactor and reacts with sponge titanium in the molten salt electrolyte. The generated titanium ions enter the molten salt electrolyte in the form of single Ti 3+ or Ti 2+ to supplement the titanium source in the molten salt electrolyte;

[0036] S4. The Ti 3+ or Ti 2+ in the molten salt electrolyte migrates to the cathode for discharge and deposition. After electrolysis, the cathode is replaced and electrolysis continues. Meanwhile, sponge titanium on the upper surface of the low-valent titanium reactor can be supplemented optionally; the deposition product on the replaced cathode is peeled off, and after being pickled, washed with water, and dried in sequence, high-purity titanium is obtained.

[0037] Preferably, an air inlet II is connected to the nozzle for introducing a carrier gas to transport the chlorination raw material.

[0038] The molten salt electrolyte containing single Ti 3+ or Ti 2+ refers to that the molten salt electrolyte contains only one valence state of titanium ions. For example, it contains Ti 3+ or Ti 2+ .

[0039] Preferably, when the molten salt electrolyte contains single Ti 3+ , the corresponding supporting electrolyte composition includes one or more of alkali metal chlorides or alkaline earth metal chlorides without Li + , and optionally also includes alkali metal fluorides or alkaline earth metal fluorides. And the molar ratio of F - in the fluoride to Ti 3+ is controlled to be 0-6. More preferably, the mass concentration of Ti 3+ in the molten salt electrolyte is 1-30%, the temperature of the molten salt electrolyte during electrolysis is controlled not to be lower than 750 °C, and the stepped constant current compensation method is used for electrolysis, and the cathode current density is controlled at 0.1-10 A / cm 2 .

[0040] Preferably, when the molten salt electrolyte contains single Ti2+ When, the corresponding supporting electrolyte composition includes an alkali metal chloride or an alkaline earth metal chloride containing Li + or several of them, preferably LiCl. More preferably, the mass concentration of Ti in the molten salt electrolyte is 1-30%, and the temperature of the molten salt electrolyte during electrolysis is controlled not higher than 650°C. The stepped constant current compensation method is used for electrolysis, and the cathode current density is controlled at 0.01-1 A / cm 2+ . 2 .

[0041] Preferably, the time of the electrolysis is 10-50 h.

[0042] Preferably, the pressure of the carrier gas is 0.1-10 atm, and the flow rate is 0.1-100 L / min. The carrier in the present invention can be a protective gas or an inert gas, which is used to transport materials and does not participate in the reaction. For example, it can be argon.

[0043] Preferably, the chlorination raw material is titanium carbon oxygen and / or titanium carbon oxygen nitrogen.

[0044] Preferably, the particle size of the chlorination raw material is crushed to less than 200 mesh.

[0045] Preferably, during the chlorination reaction, the average residence time of the materials is less than 10 min, and the reaction temperature is 150-400°C.

[0046] In the present invention, the radiant heat of the molten salt electrolyte and the waste heat of the electrolytic cell are used for heating.

[0047] Compared with the prior art, the advantages of the present invention are as follows:

[0048] (1) During the chlorination reaction, the raw materials titanium carbon oxygen / titanium carbon oxygen nitrogen and Cl2 move countercurrently, which can give full play to the characteristics of low chlorination temperature, short reaction time and high efficiency of titanium carbon oxygen / titanium carbon oxygen nitrogen, and the chlorination reaction proceeds more completely and thoroughly.

[0049] (2) Control the titanium ions in the molten salt electrolyte to be in a single valence state, and complete the deposition process of obtaining electrons in one step at the cathode, without generating intermediate valence state titanium ions, eliminating the adverse effects brought by the coexistence of multi-valence state titanium ions in the molten salt electrolysis process, and it is easier to obtain metal titanium deposits with a particle size above 1000 microns and complete crystallization, with less salt inclusion and low oxygen content in the product.

[0050] (3) The device structure of the present invention is more compact. The chlorination and electrolysis processes are completed in one electrolytic cell, and the radiant heat of the molten salt electrolyte and the waste heat of the electrolytic cell are fully utilized to provide the temperature required for the chlorination reaction, saving energy consumption. The preferred scheme of the opening horn-shaped anode cover has a higher collection efficiency of the anode gas Cl2 while not affecting the anode reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic structural diagram of a specific embodiment of the device for in-situ chlorination - cyclic electrolysis to prepare high-purity titanium according to the present invention;

[0052] Figure 2 Top view of a specific embodiment of the low-valent titanium reactor according to the present invention;

[0053] Figure 3 Side view of a specific embodiment of the low-valent titanium reactor according to the present invention.

[0054] [Reference numerals]

[0055] 1. Electrolytic cell, 2. Chlorinator, 3. Fractionator, 4. Low-valent titanium reactor, 5. Porous filter, 6. Anode hood, 7. Baffle, 8. Delivery pipe, 9. Molten salt electrolyte, 10. Sponge titanium, 11. Chlorination raw material;

[0056] 301. Gas outlet Ⅰ, 401. Through-hole outlet, 501. Nozzle, 502. Gas inlet Ⅰ, 503. Gas inlet Ⅱ, 701. Baffle through-hole, 801. Gas inlet Ⅲ. Specific embodiment

[0057] The high-purity titanium described in the present invention means that the titanium mass content in the product is ≥ 99.99% and the oxygen content is ≤ 200 ppm. In the present invention, unless otherwise specified, the materials are in terms of mass.

[0058] According to a preferred embodiment of the present invention, a device for in-situ chlorination - cyclic electrolysis to prepare high-purity titanium is as Figure 1 - Figure 2 shown, including a chlorinator 2, a fractionator 3, and an electrolytic cell 1. The chlorinator 2 is located above the liquid level of the molten salt electrolyte 9 in the electrolytic cell 1, and the chlorinator 2 is heated by the radiant heat of the molten salt electrolyte 9 and the waste heat of the electrolytic cell 1; a porous filter 5 is installed inside the chlorinator 2; an anode hood 6 is arranged at the bottom of the chlorinator 2, and the anode hood 6 is located above the anode of the electrolytic cell 1 and covers at least 1 / 4 of the anode height, and the lower part is in the shape of an open horn to timely and fully collect the anode gas Cl2; an air inlet Ⅰ 502 is arranged between the porous filter 5 and the anode hood 6 for introducing Ar gas to filter the anode gas Cl2 through the porous filter 5 and then introduce it into the chlorinator 2; a nozzle 501 is arranged at the top of the chlorinator 2, and the chlorination raw material 11 is sprayed into the chlorinator 2 through the nozzle 501 under the action of the carrier gas Ar introduced through the gas inlet Ⅱ 503, and reacts countercurrently with the Cl2 entering from below the chlorinator 2 to generate TiCl4; the upper part of the chlorinator 2 is connected to the bottom of the fractionator 3 through a pipeline, and the reacted gaseous product is transported into the fractionator 3 by the carrier gas through the pipeline.

[0059] The fractionator 3 is located outside the electrolytic cell 1, and its bottom is connected above the chlorinator 2 through a pipeline; the mixed gas coming out of the chlorinator 2 is fractionated by the fractionator 3, and the gas therein is discharged from the gas outlet Ⅰ 301 above the fractionator 3, and the TiCl4 therein enters the delivery pipe 8 from the middle of the fractionator 3 after condensation, and is transported into the low-valent titanium reactor 4 at the bottom of the electrolytic cell 1 by the carrier gas Ar introduced through the gas inlet Ⅲ 801.

[0060] The low-valent titanium reactor 4 is arranged at the bottom of the electrolytic cell 1 and is connected to the middle of the fractionator 3 through the delivery pipe 8; as Figure 2 - Figure 3 shown, the upper surface of the low-valent titanium reactor 4 is concave and has a plurality of through holes with a diameter of Φ1 - 2 mm. After the TiCl4 is transported into the low-valent titanium reactor 4 by the carrier gas, it bubbles out from the through hole outlet 401; the upper surface of the low-valent titanium reactor 4 is covered with an excessive amount of sponge titanium 10 to convert the TiCl4 into Ti 3+ or Ti 2+ in one of them to supplement the titanium source in the molten salt electrolyte 9 at any time. Preferably, the included angle between the outer tangent of the concave shape and the horizontal line is 1 - 10 °C.

[0061] A partition 7 is installed between the anode and the cathode to prevent a small amount of anode gas that may not be captured by the anode hood 6 from diffusing to react with the cathode and the deposited product; there are partition through holes 701 on the partition 7, and the Cl - and Ti n+ ions (n = 3 or 2) are transmitted through the partition through holes 701; the cathode and the low-valent titanium reactor 4 are located on the same side of the partition 7, and the anode is located on the other side of the partition 7; there is a heating and temperature control system outside the electrolytic cell 1 to control the temperature inside the electrolytic cell 1.

[0062] Preferably, the anode material of the electrolytic cell 1 of the present invention is graphite, and the cathode material is preferably pure titanium or pure nickel.

[0063] In some preferred embodiments, the method for in-situ chlorination - cyclic electrolysis to prepare high-purity titanium using the device of the present invention includes the following steps:

[0064] (1) Load the pre-prepared molten salt electrolyte 9 containing a single Ti 3+ or Ti 2+ into the electrolytic cell 1; after the electrolysis starts, the Cl -After migrating to the anode discharge, it is precipitated in the form of anode gas Cl2 and fully collected by the anode hood 6. Then, it enters the chlorinator 2 from below through the porous filter plate 5 under the carrier flow of Ar. When passing through the porous filter plate 5, a small amount of volatilized molten salt electrolyte 9 is blocked by the porous filter plate 5 and returns to the electrolytic cell 1. At the same time, the pre-crushed chlorination raw material 11, titanium carbon oxygen / titanium carbon oxygen nitrogen, is sprayed into the chlorinator 2 from above by the nozzle 501 under the carrier flow of Ar, and undergoes a chlorination reaction with the Cl2 entering from below to generate TiCl4. The reaction is as follows:

[0065] TiCxOy + Cl2 → TiCl4 + CO

[0066] Or TiCxOyNz + Cl2 → TiCl4 + CO + N2

[0067] (2) The mixed gas of TiCl4 + CO or TiCl4 + CO + N2 generated by the chlorination reaction enters the bottom of the fractionator 3 from above the chlorinator 2 through the connecting pipe. After being fractionated by the fractionator 3, the CO or CO + N2 therein is discharged from the gas outlet Ⅰ 301 above the fractionator 3, and the TiCl4 therein is condensed into a liquid state and discharged from the middle of the fractionator 3, and is sent to the low-valent titanium reactor 4 at the bottom of the electrolytic cell 1 through the carrier flow of Ar via the conveying pipe 8.

[0068] (3) The TiCl4 entering the low-valent titanium reactor 4 emerges from the through-hole outlet 401 on the upper surface of the low-valent titanium reactor 4 under the assistance of the Ar carrier flow, and reacts with the excessive sponge titanium 10 previously placed on the upper surface of the low-valent titanium reactor 4 in the molten salt electrolyte 9. The generated titanium ions enter the molten salt electrolyte 9 in the form of Ti 3+ Or Ti 2+ to supplement the titanium source in the molten salt electrolyte 9; Another function of the Ar carrier flow is to bubble and stir the molten salt electrolyte 9, homogenize the electrolyte composition, and promote the mass transfer of Cl - , Ti 3+ / Ti 2+ in the molten salt electrolyte 9.

[0069] (4) The Ti 3+ Or Ti 2+ in the molten salt electrolyte 9 migrates to the cathode for discharge and deposition, and its discharge process is a one-step electron gain process:

[0070] Ti 3+ + 3e - = Ti or Ti 2+ + 2e - = Ti

[0071] After electrolyzing for a certain period of time, replace the cathode and continue electrolyzing, while appropriately supplementing the titanium sponge 10 on the upper surface of the low-valent titanium reactor 4; strip the deposition product on the replaced cathode, and obtain high-purity titanium after pickling, water washing, and drying in sequence.

[0072] (5) Repeat the above steps 1-step 4, and the in-situ chlorination-circulating electrolysis for preparing high-purity titanium can be realized.

[0073] Preferably, the molten salt electrolyte 9 in the steps (1), (3), and (4) contains a single Ti 3+ or Ti 2+ , and its specific composition and control method are as follows:

[0074] (1) When containing a single Ti 3+ , the supporting electrolyte composition is one or more of alkali metal or alkaline earth metal chlorides without Li + ; at the same time, a certain amount of alkali metal or alkaline earth metal fluoride is assisted, and the dosage of the fluoride depends on the content of Ti 3+ . Control the molar ratio of F - in the fluoride to Ti 3+ to be 0-6; the mass percentage concentration of Ti 3+ in the molten salt electrolyte 9 is 1-30%, and the temperature of the molten salt electrolyte 9 during electrolysis is controlled not to be lower than 750 °C. Electrolyze by the stepped constant current compensation method, and control the cathode current density to be 0.1-10 A / cm 2 .

[0075] (2) When containing a single Ti 2+ , the supporting electrolyte composition is one or more of alkali metal or alkaline earth metal chlorides containing Li + , preferably LiCl; the mass percentage concentration of Ti 2+ in the molten salt electrolyte 9 is 1-30%, and the temperature of the molten salt electrolyte 9 during electrolysis is controlled not to be higher than 650 °C. Electrolyze by the stepped constant current compensation method, and control the cathode current density to be 0.01-1 A / cm 2 .

[0076] Preferably, the Ar carrier gas in the steps (1), (2), and (3) has a pressure of 0.1-10 atm and a flow rate of 0.1-100 L / min.

[0077] In the step (1), the chlorination raw material 11 titanium carbon oxygen / titanium carbon oxygen nitrogen can be a product synthesized artificially by an existing method or a commercially available product. Preferably, its particle size is broken to less than 200 mesh.

[0078] Preferably, during the chlorination reaction, the average residence time of the material is less than 10 min, the reaction temperature is 150-400 °C, and it is heated by using the radiant heat of the molten salt electrolyte 9 and the waste heat of the electrolytic cell 1.

[0079] The present invention is described in detail below in conjunction with specific embodiments. 3+ The molten salt electrolyte 9, that is, Ti in the molten salt electrolyte 9 3+ The mass percentage concentration is 3%, and the interpretation of other molten salt electrolytes 9 is the same.

[0080] Example 1

[0081] Preparation of CsCl-3%Ti 3+ Molten salt electrolyte 9. High purity graphite anode, pure titanium cathode, cathode current density 0.6A / cm 2 . During electrolysis, the temperature of the molten salt electrolyte 9 is controlled at 750°C, and the temperature of the chlorination reactor is 260-380°C. After the start of electrolysis, Cl2 is precipitated on the graphite anode, and enters from the bottom of the chlorinator 2 through the porous filter 5 under the Ar carrier flow; at the same time, the raw titanium carbon oxide fine powder is sprayed out from the nozzle 501 located above the chlorinator 2, and undergoes a chlorination reaction with Cl2 during the falling process to generate TiCl4, and then the gaseous by-products are separated by the fractionator 3, and then directly transported by the Ar carrier flow into the low-valent titanium reactor 4 located at the bottom of the electrolytic cell 1. When TiCl4 emerges from the through-hole outlet 401 on the upper surface of the low-valent titanium reactor 4, it reacts with the sponge titanium 10 to directly generate Ti 3+ At the same time, Ti in the molten salt 3+ Migrate to the cathode for discharge deposition as metallic titanium. After 30 hours of electrolysis, replace the cathode to continue electrolysis, and add appropriate amount of titanium sponge 10 on the low-cost titanium reactor 4. The deposited product on the replaced cathode is peeled off and sequentially treated with acid washing, water washing and drying.

[0082] After weighing and analysis, the carbon and oxygen recovery rate of the raw titanium (calculated as metallic titanium) is 89%; the salt inclusion rate of the cathode product is 15%, and the metallic titanium obtained after cleaning is dendritic crystals with a crystal particle size of 3-10mm, a purity of 99.99%, an oxygen content of less than 80ppm, and a cathode current efficiency of 92%.

[0083] Example 2

[0084] Preparation of NaCl-KCl-5.5%Ti 3+ -26% KF molten salt electrolyte 9. High purity graphite anode, pure titanium cathode, cathode current density 3A / cm 2During electrolysis, the temperature of the molten salt electrolyte 9 is controlled at 800 °C, and the temperature of the chlorination reactor is 280 - 400 °C at this time. After the electrolysis starts, Cl2 is deposited on the graphite anode, and enters from below the chlorinator 2 through the porous filter 5 under the Ar carrier flow; at the same time, the raw material titanium carbon oxygen fine powder is ejected from the nozzle 501 above the chlorinator 2, and undergoes a chlorination reaction with Cl2 during the falling process to generate TiCl4. After separating the gaseous by-products through the fractionator 3, it is directly transported by the Ar carrier flow into the low-valent titanium reactor 4 at the bottom of the electrolytic cell 1. When TiCl4 emerges from the through-hole outlet 401 on the upper surface of the low-valent titanium reactor 4, it reacts with the sponge titanium 10 to directly generate Ti 3+ Meanwhile, Ti in the molten salt 3+ migrates to the cathode and is deposited by discharging to form metallic titanium in one step. After 20 hours of electrolysis, the cathode is replaced and electrolysis continues, and the sponge titanium 10 on the low-valent titanium reactor 4 is appropriately supplemented. The deposited product on the replaced cathode is peeled off and sequentially treated by pickling, water washing, and drying.

[0085] After weighing and analysis, the recovery rate of the raw material titanium carbon oxygen (calculated as metallic titanium) is 86%; the salt inclusion rate of the cathode product is 23%. The obtained metallic titanium after cleaning is granular crystals, the crystal grain size is 1 - 5 mm, the purity is 99.99%, the oxygen content is less than 120 ppm, and the cathode current efficiency is 92%.

[0086] Example 3

[0087] Prepare a molten salt electrolyte 9 of LiCl - KCl - 8% Ti 2+ Using a high-purity graphite anode and a pure titanium cathode, the cathode current density is 0.3 A / cm 2 During electrolysis, the temperature of the molten salt electrolyte 9 is controlled at 500 °C, and the temperature of the chlorination reactor is 180 - 300 °C at this time. After the electrolysis starts, Cl2 is deposited on the graphite anode, and enters from below the chlorinator 2 through the porous filter 5 under the Ar carrier flow; at the same time, the raw material titanium carbon oxygen fine powder is ejected from the nozzle 501 above the chlorinator 2, and undergoes a chlorination reaction with Cl2 during the falling process to generate TiCl4. After separating the gaseous by-products through the fractionator 3, it is directly transported by the Ar carrier flow into the low-valent titanium reactor 4 at the bottom of the electrolytic cell 1. When TiCl4 emerges from the through-hole outlet 401 on the upper surface of the low-valent titanium reactor 4, it reacts with the sponge titanium 10 to directly generate Ti 3+ Meanwhile, Ti in the molten salt 2+ migrates to the cathode and is deposited by discharging to form metallic titanium in one step. After 40 hours of electrolysis, the cathode is replaced and electrolysis continues, and the sponge titanium 10 on the low-valent titanium reactor 4 is appropriately supplemented. The deposited product on the replaced cathode is peeled off and sequentially treated by pickling, water washing, and drying.

[0088] After weighing and analysis, the recovery rate of titanium, carbon, and oxygen in the raw materials (calculated as metallic titanium) is 87%; the salt inclusion rate of the cathode product is 17%. The metallic titanium obtained after cleaning is dendritic crystals, with a crystal grain size of 5 - 12 mm, a purity of 99.99%, an oxygen content of less than 70 ppm, and a cathode current efficiency of 90%.

[0089] Comparative Example 1

[0090] Prepare molten salt electrolyte 9 of NaCl - KCl - 5.5% Ti n+ (n = 2 and 3, with the total mass content of Ti being 5.5%). Use a high - purity graphite anode and a pure titanium cathode, with a cathode current density of 0.6 A / cm 2 . During electrolysis, the temperature of the molten salt electrolyte 9 is controlled at 800 °C, and at this time, the temperature of the chlorination reactor is 280 - 400 °C. After the electrolysis starts, Cl2 is deposited on the graphite anode and enters from below the chlorinator 2 through the porous filter plate 5 under the Ar carrier flow; meanwhile, the fine powder of titanium, carbon, and oxygen in the raw materials is ejected from the nozzle 501 above the chlorinator 2, and during the falling process, it undergoes a chlorination reaction with Cl2 to form TiCl4. After separating the gaseous by - products through the fractionator 3, it is directly transported by the Ar carrier flow into the low - valent titanium reactor 4 at the bottom of the electrolytic cell 1. When TiCl4 emerges from the through - hole outlet 401 on the upper surface of the low - valent titanium reactor 4, it reacts with the sponge titanium 10 to form Ti 3+ and Ti 2+ . At the same time, Ti 3+ and Ti 2+ in the molten salt migrate to the cathode. Among them, Ti 3+ is deposited as metallic titanium through two - step discharge of Ti 3+ →Ti 2+ →Ti, and Ti 2+ is deposited as metallic titanium through the discharge of Ti 2+ →Ti. After 30 hours of electrolysis, the cathode is replaced and electrolysis continues, and an appropriate amount of sponge titanium 10 on the low - valent titanium reactor 4 is replenished. The deposition product on the replaced cathode is peeled off and successively treated by pickling, water washing, and drying.

[0091] After weighing and analysis, the recovery rate of titanium, carbon, oxygen / titanium, carbon, oxygen, and nitrogen in the raw materials (calculated as metallic titanium) is 69%; the salt inclusion rate of the cathode product is 18%. The metallic titanium obtained after cleaning is a mixture of dendritic crystals and granular crystals, with a crystal grain size of 0.01 - 10 mm, a purity of 99.96%, an oxygen content of 200 - 400 ppm, and a cathode current efficiency of 73%.

[0092] As can be seen from the above, the main difference between Comparative Example 1 and Examples 1 - 3 is that Comparative Example 1 did not control the valence state of titanium ions in the molten salt electrolyte, resulting in the appearance of Ti 3+ and Ti 2+In the coexisting situation, it ultimately led to a large amount of fine powder with a particle size below 1 mm in the deposited product, reducing the product purity while increasing the oxygen content, and the cathode current efficiency and raw material recovery rate also decreased significantly.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for preparing high-purity titanium by in-situ chlorination-cyclic electrolysis, characterized in that, Comprising: An electrolytic cell, which is provided with an anode, a cathode and a molten salt electrolyte containing a single Ti 3+ or Ti 2+ ; A chlorinator, which is located above the molten salt electrolyte level in the electrolytic cell and above the anode, to heat the chlorinator using the radiant heat of the molten salt electrolyte and the waste heat of the electrolytic cell, and utilize the anode gas Cl2; the chlorinator includes a nozzle at the top for introducing chlorination raw materials; A fractionator, which is located outside the electrolytic cell and communicates with the upper part of the chlorinator, for fractionating the mixed gas coming out of the chlorinator; A low-valent titanium reactor is provided at the bottom of the electrolytic cell and near the cathode. It includes a gas inlet at the bottom, a number of through-hole outlets at the top, and sponge titanium above the top. The gas inlet is communicated with the gas outlet of the fractionator; it is used to convert TiCl4 coming out of the fractionator into Ti 3+ or Ti 2+ in one of them to supplement the titanium source in the molten salt electrolyte at any time.

2. The device according to claim 1, characterized in that The device further includes: An anode hood, which is arranged at the bottom of the chlorinator and communicates, and is located above the anode in the electrolytic cell and covers at least 1 / 4 of the anode height, so as to timely and fully collect the anode gas Cl2.

3. The device according to claim 2, characterized in that The lower part of the anode hood is in the shape of an open trumpet, and its inner diameter at the lower part increases successively from top to bottom.

4. The device according to claim 1, characterized in that The chlorinator further includes: A porous filter sheet, which is laid flat inside the chlorinator and divides the chlorinator into upper and lower chambers for filtering the anode gas Cl2; Optionally, an air inlet I is arranged between the bottom of the chlorinator and the porous filter sheet, and the air inlet I is opened on the side wall of the chlorinator for introducing a carrier gas to filter the anode gas Cl2 through the porous filter sheet and then introduce it into the chlorinator.

5. The device according to claim 1, wherein The upper surface of the low-valent titanium reactor is concave and has a number of through-hole outlets, so that the material emerges from the through-hole outlets in a bubbling manner; the included angle between the outer tangent of the concave shape and the horizontal line is 1-10 °C; among the number of through-hole outlets at the top of the low-valent titanium reactor, one is located in the middle of the top, and the rest of the through-hole outlets are arranged at intervals along the circumferential direction; And / or, connect the gas inlet of the low-valent titanium reactor and the gas outlet of the fractionator through a connecting pipe, and an air inlet III is connected to the connecting pipe for introducing a carrier gas to transport TiCl4 into the low-valent titanium reactor.

6. The device according to any one of claims 1-5, characterized in that, The device further includes: A partition board, which is arranged in the electrolytic cell and is located between the anode and the cathode and extends upward along the molten salt electrolyte level, and the partition board is provided with partition board through-holes; the cathode and the low-valent titanium reactor are located on the same side of the partition board; An optional heating and temperature control system, which is arranged outside the electrolytic cell for controlling the temperature in the electrolytic cell.

7. A method for preparing high-purity titanium by in-situ chlorination-circulating electrolysis, characterized in that, Carried out using the device according to claim 4 or 5, and the method includes the following steps: S1. Load the pre-prepared molten salt electrolyte containing a single Ti 3+ or Ti 2+ into the electrolytic cell; the anodic gas Cl2 electrolytically evolved enters the chlorinator; at the same time, the pre-crushed chlorination raw material is sprayed into the chlorinator by a nozzle to react with Cl2 to generate TiCl4, obtaining a mixed gas containing TiCl4; S2. The mixed gas enters the fractionator from the chlorinator, and after fractionation, the CO or CO+N2 therein is discharged from the gas outlet I above the fractionator, and the TiCl4 therein is condensed into a liquid state and then transported to the low-valent titanium reactor located at the bottom of the electrolytic cell; S3. The TiCl4 entering the low-valent titanium reactor emerges from the through-hole outlet of the low-valent titanium reactor and reacts with titanium sponge in the molten salt electrolyte. The generated titanium ions enter the molten salt electrolyte in the form of single Ti 3+ or Ti 2+ to supplement the titanium source in the molten salt electrolyte; S4. Ti in the molten salt electrolyte 3+ Or Ti 2+ Migrates to the cathode for discharge and deposition. After electrolysis, the cathode is replaced to continue electrolysis, and at the same time, sponge titanium on the upper surface of the low-valent titanium reactor is optionally supplemented; the deposition products on the replaced cathode are stripped, and after pickling, water washing, and drying treatments in sequence, high-purity titanium is obtained.

8. The method according to claim 7, wherein The molten salt electrolyte contains a single Ti 3+ When it is, the corresponding supporting electrolyte composition includes one or more of alkali metal chlorides or alkaline earth metal chlorides without Li + , and optionally also includes alkali metal fluorides or alkaline earth metal fluorides, and controls the F in the fluoride - The molar ratio of Ti 3+ is 0-6; and / or, the mass concentration of Ti in the molten salt electrolyte 3+ is 1-30%, the temperature of the molten salt electrolyte during electrolysis is controlled not to be lower than 750 °C, and the stepped constant current compensation method is used for electrolysis, and the cathode current density is controlled at 0.1-10 A / cm 2 ; The molten salt electrolyte contains a single Ti 2+ When it is, the corresponding supporting electrolyte composition includes one or more of alkali metal chlorides or alkaline earth metal chlorides containing Li + ; and / or, the mass concentration of Ti in the molten salt electrolyte is 1-30%, and the temperature of the molten salt electrolyte is controlled not to be higher than 650 °C during electrolysis. The stepped constant current compensation method is used for electrolysis, and the cathode current density is controlled at 0.01-1 A / cm 2+ . 2 ​ 9. The method according to claim 8, wherein The molten salt electrolyte contains a single Ti 2+ When this is the case, the corresponding supporting electrolyte is LiCl.

10. The method according to claim 7, wherein The pressure of the carrier gas is 0.1-10 atm, and the flow rate is 0.1-100 L / min.

11. The method according to claim 7, wherein The chlorination raw material is titanium carbon oxygen and / or titanium carbon oxygen nitrogen, and the particle size of the chlorination raw material is broken to less than 200 mesh; And / or, during the chlorination reaction, the average residence time of the material is less than 10 min, the reaction temperature is 150-400 °C, and the radiant heat of the molten salt electrolyte and the waste heat of the electrolytic cell are used for heating.

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