Method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt
阅读说明：本技术 一种氟化物熔盐中二氧化钛溶解-电解制备金属钛的方法 (Method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt ) 是由 颜恒维 刘战伟 马文会 杨斌 刘瑛鑫 秦博 徐宝强 魏奎先 李绍元 吕国强 雷云 于 2021-07-30 设计创作，主要内容包括：本发明涉及一种氟化物熔盐中二氧化钛溶解-电解制备金属钛的方法,属于金属钛制备技术领域。本发明以TiO-2为原料,将TiO-2直接加入nNaF-KTiF-4氟化物熔盐体系中溶解,同时以石墨或金属材料作为电解槽的阳极,以金属材料为电解槽的阴极,在密闭的电解槽中通入惰性保护气氛中进行电解,电解后的阴极产物使用真空蒸馏或者稀盐酸溶液洗涤的方法除去附着的电解质后得到金属钛。本发明方法直接把TiO-2溶解到氟化物熔盐中进行电解,其方法简单,流程较短,成本较低,产物纯度较高。(The invention relates to a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt, belonging to the technical field of metal titanium preparation. In the invention, TiO is used 2 Using TiO as raw material 2 Directly adding nNaF-KTiF 4 Dissolving in a fluoride molten salt system, simultaneously taking graphite or a metal material as an anode of an electrolytic cell, taking the metal material as a cathode of the electrolytic cell, introducing inert protective atmosphere into a closed electrolytic cell for electrolysis, and removing attached electrolyte from the cathode product after electrolysis by using a vacuum distillation or dilute hydrochloric acid solution washing method to obtain the metallic titanium. The method of the invention directly prepares TiO 2 Dissolving the product into fluoride molten salt for electrolysis, and the method is simple, short in flow, low in cost and high in product purity.)
1. A method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt is characterized by comprising the following specific steps: adding TiO into the mixture2Directly adding into nNaF-KTiF4Dissolving in fluoride molten salt system at 20-80 deg.C under inert atmosphere, performing cathode-anode current density differential electrolysis with carbon or metal material as anode and metal material as cathode of the electrolytic cell, and vacuum distilling or washing with dilute hydrochloric acid solution to remove cathode productRemoving the adhered electrolyte to obtain metal titanium, wherein the electrolytic cell is of a sealed structure, nNaF-KTiF4N in the formula is NaF and KTiF4The molar ratio of (a), n is 0.6-4, and the superheat degree is the difference between the electrolysis temperature and the primary crystallization temperature of the molten salt, namely the superheat degree = the electrolysis temperature-the primary crystallization temperature of the molten salt.
2. The method for preparing metallic titanium by dissolution-electrolysis of titanium dioxide in fluoride molten salt according to claim 1, characterized in that: nNaF-KTiF4The fluoride molten salt system contains CaF2、MgF2One or more of LiF, nNaF-KTiF4NaF and KTiF in fluoride molten salt system4The total content of the component (C) is not less than 92 wt%, CaF2、MgF2And the content of any one of LiF is not more than 6 wt%.
3. The method for preparing metallic titanium by dissolution-electrolysis of titanium dioxide in fluoride molten salt according to claim 1 or 2, characterized in that: the primary crystal temperature of the molten salt is 630-880 ℃, the electrolysis temperature is 650-900 ℃, and the TiO is added at the electrolysis temperature2In nNaF-KTiF4The solubility in the fluoride molten salt system is not less than 4 wt%.
4. The method for preparing metallic titanium by dissolution-electrolysis of titanium dioxide in fluoride molten salt according to claim 3, characterized in that: when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 0.6-2.5A/cm2The current density of the anode is 0.2-1A/cm2And the cathode current density is 2-6 times of the anode current density.
Technical Field
The invention relates to a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt, belonging to the technical field of metal titanium preparation.
Background
Titanium is an important metal, has the advantages of small density, high specific strength, heat resistance, no magnetism, weldability and the like, and titanium and alloys thereof are widely applied to the fields of aviation, aerospace, petroleum, chemical industry, metallurgy, medical treatment and the like, particularly the fields of aerospace and navigation.
Currently, the only method for industrially producing metallic titanium is the magnesiothermic reduction method, also known as Kroll method. The process is to put magnesium metal into a reactor and fill argon for protection, heat to 800-900 ℃, and then add titanium tetrachloride and magnesium vapor at a certain speed to react to produce titanium sponge. The process has the defects of non-continuity, complex production process, high cost, high energy consumption, great environmental pollution and the like. The high cost of the smelting method causes the price of titanium and titanium alloy to be higher, and limits the wide application of the titanium and the titanium alloy materials.
In the prior art, TiO is adopted for preparing metal titanium by a molten salt electrolysis method2Is prepared from CaCl2Deoxidizing the cathode in molten salt to produce titanium sponge, but the raw material utilization rate is low, the electrolytic deoxidation efficiency is low, and the oxygen content of the product is high; in CaCl2Method for preparing TiO from active calcium obtained by electrolysis in molten salt2Reduced to titanium metal, but low current efficiency, incomplete reaction of raw materials and impurity content of productsHigh purity requirement of the raw material titanium dioxide; with TiO2And C are mixed according to the stoichiometric ratio and are thermally reduced at 1100-1300 ℃ to obtain a low-valence compound of titanium, and the low-valence compound is used as a composite anode to be electrolyzed in an alkali metal molten salt system to obtain the metallic titanium. The composite anode is a mixed material of a low-valence titanium compound of titanium and carbon, and residual carbon covers the surface of the anode in the electrochemical dissolution process to prevent the further dissolution of the anode, so that the problem of low anode dissolution rate exists; titanium dioxide and graphite are used as raw materials, a low-valence compound of titanium with good conductivity is produced by vacuum carbothermic reduction at 1500 ℃, the low-valence compound is used as a soluble anode material to extract high-purity metallic titanium by electrolysis in a NaCl-KCl molten salt system at 700 ℃, or a titanium-containing material and a carbon-containing reducing agent are mixed to be used as raw materials, the raw materials are uniformly mixed and then are pressed and molded, the mixture is roasted in a nitrogen-containing atmosphere at 1000-2000 ℃ to prepare a titanium-containing compound with good conductivity, and then the titanium-containing compound is used as an anode to extract metallic titanium by electrolysis in halide molten salt of alkali metal or alkaline earth metal, however, the process also has the problem of low anode dissolution rate; titanium tetrachloride is used as a raw material, metal titanium is used for reduction to obtain low-valence titanium chloride, and then the metal titanium is obtained through molten salt electrolysis, so that the problems of expensive raw material, low reaction rate, high cost and the like exist; liquid metal (bismuth, tin, lead and the like) is used as a cathode, and titanium sponge or soluble titanium-containing substances (titanium-carbon-oxygen solid solution and the like) are used as an anode for electrolysis. After the electrolysis is finished, distilling the cathode titanium alloy product at high temperature to finally obtain high-purity titanium metal; sintering titanium dioxide powder to obtain a sintered body, and then taking the sintered body and a metal molybdenum wire as cathodes, graphite as anodes and NaF and AlF as anodes3The mixture melt is used as electrolyte to be electrolyzed to obtain metal titanium powder; sintering titanium dioxide powder to obtain a sintered body, and then taking the sintered body and a metal molybdenum wire as cathodes, graphite as anodes and NaF and AlF as anodes3The mixture melt is used as electrolyte to be electrolyzed to obtain metal titanium powder; electrolyzing a titanium-containing conductive ceramic anode and a rotary cathode in a molten salt electrolytic bath, continuously transferring metal titanium powder deposited on the surface of the cathode to the upper part of molten salt by the rotary cathode, cleaning the separated metal titanium powder by using deoxygenated deionized water, and finally drying in vacuum to obtain prepared metal titanium powder;titanium dioxide is used as a raw material, and hydrogen is used as a reducing agent to prepare Ti4O7Powder, and then Ti obtained by reduction with anhydrous calcium chloride as molten salt and graphite as anode4O7The powder is used as a cathode, and metallic titanium is obtained through molten salt electrolysis.
However, the molten salt electrolysis method in the prior art for preparing the metal titanium has the problems of expensive raw materials, complex flow, high cost and the like.
Disclosure of Invention
Aiming at the problems of high cost, low raw material utilization rate, high product impurity content and the like in the production process of metal titanium in the prior art, the invention provides a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt, namely directly dissolving TiO2Dissolving the product into fluoride molten salt for electrolysis, and the method is simple, short in flow, low in cost and high in product purity.
A method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps: adding TiO into the mixture2Directly adding into nNaF-KTiF4Dissolving in fluoride molten salt system at 20-80 deg.C under inert atmosphere, performing cathode and anode current density differential electrolysis with graphite or metal material as anode and metal material as cathode of the electrolytic cell, vacuum distilling the electrolyzed cathode product or washing with dilute hydrochloric acid solution to remove the adhered electrolyte to obtain metal titanium, wherein the electrolytic cell is of sealed structure, and nNaF-KTiF4N in the formula is NaF and KTiF4The molar ratio of (a), n is 0.6-4, and the superheat degree is the difference between the electrolysis temperature and the primary crystal temperature of the molten salt, namely the superheat degree = the electrolysis temperature-the primary crystal temperature of the molten salt;
the nNaF-KTiF4The fluoride molten salt system contains CaF2、MgF2One or more of LiF, nNaF-KTiF4NaF and KTiF in fluoride molten salt system4The total content of the component (C) is not less than 92 wt%, CaF2、MgF2The content of any one of LiF is not more than 6 wt%;
the primary crystal temperature of the molten salt is 630-880 ℃, and the electrolysis temperature is 650-900 ℃; at the electrolysis temperature, TiO2In nNaF-KTiF4Solubility in the fluoride molten salt system is not less than 4 wt%;
when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 0.6-2.5A/cm2The current density of the anode is 0.2-1A/cm2The cathode current density is 2-6 times of the anode current density;
the inert atmosphere is nitrogen atmosphere or argon atmosphere;
the anode metal material is high-temperature resistant materials such as tungsten, molybdenum, Hastelloy, cupronickel, 310S stainless steel and the like, and the cathode metal material is titanium, tungsten, molybdenum, 316 stainless steel, 310S stainless steel or Hastelloy.
The invention has the beneficial effects that:
(1) the invention discloses nNaF-KTiF4The solubility of titanium dioxide in a fluoride molten salt system is not less than 4wt%, and the titanium dioxide is in nNaF-KTiF4Dissolving in a fluoride molten salt system to form Ti-O-F and/or Ti-F complex ions, wherein in the cathode and anode current density differential electrolysis process, oxygen in the Ti-O-F complex ions is oxidized at the anode, and titanium in the Ti-F complex ions is reduced to simple substance titanium at the cathode;
(2) the method directly uses titanium dioxide as a raw material, namely nNaF-KTiF4High-purity titanium is prepared by dissolution and electrolysis in a fluoride molten salt system, so that the preparation cost of the titanium is reduced;
(3) the invention discloses nNaF-KTiF4The electrochemical window of the electrolyte in the fluoride molten salt system is wider, and the anode does not generate fluorine gas during electrolysis;
(4) the method can prevent the generation of titanium suboxide and realize the continuous production of the metallic titanium.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.
Example 1: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 1.5NaF-KTiF4Molten fluoride salt system (20.8 w)t%NaF-79.2wt%K2TiF6) Dissolving the titanium alloy in a nitrogen atmosphere at the superheat degree of 20-60 ℃, simultaneously using a graphite material as an anode of an electrolytic cell, using a titanium plate as a cathode of the electrolytic cell, carrying out cathode-anode current density differential electrolysis at the temperature of 780-plus-810 ℃, and removing attached electrolyte from an electrolyzed cathode product through vacuum distillation to obtain metal titanium, wherein the superheat degree is the difference between the electrolysis temperature and the molten salt primary crystal temperature, namely the superheat degree = the electrolysis temperature-the molten salt primary crystal temperature; TiO 22At 1.5NaF-KTiF4The solubility in the fluoride molten salt system is more than 5.8 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 1.5A/cm2The current density of the anode is 0.3A/cm2The cathode current density is 5 times of the anode current density;
the purity of the metallic titanium in this example was 99.8%.
Example 2: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 1.0NaF-KTiF4Molten fluoride salt system (14.9 wt% NaF-85.1wt% K)2TiF6) Dissolving the titanium alloy in a nitrogen atmosphere at the superheat degree of 30-70 ℃, simultaneously using tungsten as an anode of an electrolytic cell, using Hastelloy as a cathode of the electrolytic cell, performing cathode-anode current density differential electrolysis at the temperature of 730-; TiO 22At 1.0NaF-KTiF4The solubility in the fluoride molten salt system is more than 6.8 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 1.6A/cm2The current density of the anode is 0.4A/cm2The cathode current density is 4 times of the anode current density;
the purity of the metallic titanium in this example was 99.6%.
Example 3: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 4.0NaF-KTiF4Molten fluoride salt system (41.1 wt% NaF-58.9wt% K)2TiF6) Dissolving the titanium alloy in a nitrogen atmosphere at the superheat degree of 30-50 ℃, simultaneously using molybdenum as an anode of an electrolytic cell, using 316 stainless steel as a cathode of the electrolytic cell, performing cathode-anode current density differential electrolysis at 880-900 ℃, and removing attached electrolyte from an electrolyzed cathode product through vacuum distillation to obtain metal titanium, wherein the superheat degree is the difference between the electrolysis temperature and the primary crystal temperature of molten salt, namely the superheat degree = the electrolysis temperature-the primary crystal temperature of the molten salt; TiO 22At 4.0NaF-KTiF4The solubility in the fluoride molten salt system is more than 4.1 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 1.2A/cm2The current density of the anode is 0.3A/cm2The cathode current density is 4 times of the anode current density;
the purity of the metallic titanium in this example was 99.3%.
Example 4: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 1.5NaF-KTiF4Molten fluoride salt System (4 wt% CaF)2-20wt%NaF-76wt%K2TiF6) Dissolving at 30-70 ℃ of superheat degree, dissolving in nitrogen atmosphere, simultaneously using 310S stainless steel as an anode of an electrolytic cell, using a titanium rod as a cathode of the electrolytic cell, performing cathode-anode current density differential electrolysis at 770-810 ℃, and removing attached electrolyte from an electrolyzed cathode product through vacuum distillation to obtain metal titanium, wherein the superheat degree is the difference between the electrolysis temperature and the molten salt primary crystal temperature, namely the superheat degree = the electrolysis temperature-the molten salt primary crystal temperature; TiO 22At 1.5NaF-KTiF4The solubility in the fluoride molten salt system is more than 5.2 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 2.5A/cm2The current density of the anode is 0.5A/cm2The cathode current density is 5 times of the anode current density;
the purity of the metallic titanium in this example was 99.6%.
Example 5: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 1.5NaF-KTiF4Molten fluoride salt System (5 wt% CaF)2-3wt%LiF-19.1wt%NaF -72.9wt%K2TiF6) Dissolving the titanium alloy in a nitrogen atmosphere at the superheat degree of 40-80 ℃, simultaneously using a graphite material as an anode of an electrolytic cell, using a titanium rod as a cathode of the electrolytic cell, carrying out cathode-anode current density differential electrolysis at the temperature of 750-800 ℃, and removing attached electrolyte from an electrolyzed cathode product through vacuum distillation to obtain metal titanium, wherein the superheat degree is the difference between the electrolysis temperature and the molten salt primary crystal temperature, namely the superheat degree = the electrolysis temperature-the molten salt primary crystal temperature; TiO 22At 1.5NaF-KTiF4The solubility in the fluoride molten salt system is more than 4.9 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 2.0A/cm2The current density of the anode is 0.5A/cm2The cathode current density is 4 times of the anode current density;
the purity of the metallic titanium in this example was 99.7%.
Example 6: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 2.0NaF-KTiF4Molten fluoride salt System (4 wt% CaF)2-4wt%MgF2-23.9wt%NaF -68.1wt%K2TiF6) Dissolving the titanium alloy in a nitrogen atmosphere at the superheat degree of 30-60 ℃, simultaneously using a graphite material as an anode of an electrolytic cell, using a titanium rod as a cathode of the electrolytic cell, carrying out cathode-anode current density differential electrolysis at the temperature of 785-815 ℃, washing an electrolyzed cathode product by a dilute hydrochloric acid solution to remove attached electrolyte to obtain metal titanium, wherein the superheat degree is the difference between the electrolysis temperature and the primary crystal temperature of molten salt, namely the superheat degree = the electrolysis temperature-the primary crystal temperature of the molten salt; TiO 22At 2.0NaF-KTiF4The solubility in the fluoride molten salt system is more than 4.5 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 1.0A/cm2The current density of the anode is 0.3A/cm2Cathode electrodeThe current density is 3.3 times of the anode current density;
the purity of the metallic titanium in this example was 99.6%.
Example 7: a method for preparing metal titanium by dissolving and electrolyzing titanium dioxide in fluoride molten salt comprises the following specific steps:
with TiO2Using powdered TiO as raw material2Directly adding into 0.7NaF-KTiF4Molten fluoride salt system (10 wt% NaF-82wt% K)2TiF6-6wt%CaF2-2wt% LiF), dissolving at 30-60 ℃ of superheat degree and under nitrogen atmosphere, simultaneously using graphite material as an anode of an electrolytic cell, using a titanium plate as a cathode of the electrolytic cell, performing cathode-anode current density differential electrolysis at 660-720 ℃, washing the electrolyzed cathode product by a dilute hydrochloric acid solution to remove attached electrolyte to obtain metal titanium, wherein the superheat degree is the difference between the electrolysis temperature and the molten salt primary crystallization temperature, namely the superheat degree = the electrolysis temperature-the molten salt primary crystallization temperature; TiO 22At 0.7NaF-KTiF4The solubility in the fluoride molten salt system is more than 5.5 wt%; when the current density of the cathode and the anode is subjected to differential electrolysis, the current density of the cathode is 1.5A/cm2The current density of the anode is 0.4A/cm2The cathode current density is 3.75 times of the anode current density;
the purity of the metallic titanium in this example was 99.7%.
While the present invention has been described in detail with reference to the specific embodiments thereof, the present invention is not limited to the embodiments described above, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.