CN113699560A

CN113699560A - Method for preparing metal titanium by soluble anode electrolysis of fluorine-chlorine mixed molten salt system

Info

Publication number: CN113699560A
Application number: CN202110810003.1A
Authority: CN
Inventors: 高锋; 邹本善; 龙文元; 韦悦周; 李伟洲
Original assignee: Guangxi University
Current assignee: Guangxi University
Priority date: 2021-07-17
Filing date: 2021-07-17
Publication date: 2021-11-26
Anticipated expiration: 2041-07-17
Also published as: CN113699560B

Abstract

A method for preparing metal titanium by soluble anode electrolysis of a fluorine-chlorine mixed molten salt system. The invention relates to the field of metallurgy, in particular to a method for preparing metallic titanium using titanium dioxide as a raw material, which mainly includes two steps of preparing a high-conductivity titanium carbon oxide anode and electrolysis of a fluorine-chlorine mixed system soluble anode molten salt. High-purity metal titanium products are prepared by using secondary fine grinding, secondary briquetting, secondary roasting, pre-electrolysis, mixed molten salt and other special processes. Both roasting and electrolysis are carried out in an argon atmosphere. In addition to adding some process steps, this technology inherits the advantages of other soluble anode electrolysis, such as low cost of raw materials, easy operation, and continuous production. In addition, the present invention has lower requirements for equipment sealing and electrolytic stability. Better current efficiency and higher product purity for industrial applications.

Description

Method for preparing metal titanium by soluble anode electrolysis of fluorine-chlorine mixed molten salt system

Technical Field

The invention relates to a method for preparing metallic titanium, belonging to the field of non-ferrous metallurgy.

Background

Titanium and its alloy have excellent physical, chemical properties, have density small, intensity high, high temperature resistant and characteristic such as being corrosion-resistant, it is important light construction material, new functional material, apply to civil fields such as aerospace, war industry and chemical industry, boats and ships, building, sports equipment, medical instrument, biomedicine extensively, be praised as "future metal", "third metal". The preparation of titanium sponge by a magnesium reduction method (Kroll method) is the only international method for industrially producing metal titanium (titanium sponge), however, the Kroll process is discontinuous, and materials must be loaded and unloaded discontinuously and high-temperature heating operation is required in the production process, so that the energy consumption is high, the period is long, and the production cost is high. In addition, the chlorinating agent is highly corrosive, easily corrodes equipment, worsens labor conditions and pollutes the environment, thereby limiting wider application of the metallic titanium. Therefore, the development of new titanium metallurgy technology with low cost, simple process, cleanness and high efficiency is a problem and an effort direction which are always concerned.

In the last 20 years, numerous colleges and scientific research institutions at home and abroad including Norwegian university of science and technology and Cambridge university and various titanium metallurgy enterprises including DuPont company strive to explore methods for producing metallic titanium by replacing magnesiothermic reduction, a titanium dioxide cathode deoxidation process developed by Cambridge university utilizes a direct electrical reduction process (also called FFC method) to remove oxygen from a metal oxide raw material, the process can directly use titanium dioxide as a cathode raw material, titanium sponge (Nature.2000,407:361-₂Preparation of TiO in titanium sponge₂Method for preparing cathode; CN1664173 discloses a method for preparing titanium sponge by electrolyzing titanium dioxide with molten salt; CN107587168A discloses a method for preparing metallic titanium by molten salt electrolysis. The method has the advantage of low costThe titanium dioxide is used as a raw material, the production flow is short, and toxic chlorine is not generated in the production process. However, this method has problems that the solid phase diffusion rate of oxygen in the cathode region is slow, the current efficiency is low, and the content of impurities in the metallic titanium obtained by electrolysis is high. TiO is utilized in electrochemical calcium thermal reduction process developed by Kyoto university₂Or an oxide mixture thereof, (see Metallurgical and Materials Transactions B2003, 34:287-295) which also has the advantages of low raw material cost and short process flow, but the reaction process of the method firstly needs CaCl electrolysis₂Liquid metal calcium is generated, and then TiO is reduced by calcium heat₂The method for preparing the metallic titanium has low production efficiency, and the calcium-titanium alloy product is not easy to be thoroughly separated to influence the purity of the metallic titanium. The Japanese research group utilized CaF₂Iso-molten salt direct dissolution of TiO₂And electrolysis was carried out to obtain liquid metallic titanium (Electrochemistry, 1999, 67: 661-. Electrolysis of TiO-containing melts at high temperatures by the total oxide melt electrolysis method proposed by the professor Sadoway in Ma province's science of engineering₂To produce liquid metal titanium and at the same time produce O at the anode₂(J Materials Research, 1995(10):487-492), the process is simple, can be produced continuously, and is environmentally friendly, but because the electrolysis is carried out at a high temperature of 1700 ℃, the expensive special metal anode material is required, and the production cost is high.

The "soluble anode electrolysis of Titanium oxycarbide" was originally proposed by e.wainer in the united states and uses a mixture of TiC and TiO as raw Material to deposit Titanium sponge on a cathode by an arc melting high temperature Process (e.g., Cell fed materials for the Production of Titanium, US 2868703, and Thermal and Electrochemical processes for Metal Production, US 2722509), but this Process is too costly in raw Material. Subsequently, MER in the United states was treated with TiO₂Or the rutile powder is uniformly mixed with carbon-containing and caking agent, compression molding and heat treatment are carried out to prepare the soluble anode, and ilmenite is used as the raw material to prepare the ferrotitanium alloy (see Warrendale, PA: TMS, 2007: 117-126). The Beijing university of science and technology research group developed similar titaniumThe preparation method is called as USTB process (CN1712571 discloses a method for producing pure titanium by electrolyzing a soluble titanium monoxide/titanium carbide solid solution anode, and CN103451682A discloses a method for extracting metallic titanium by electrolyzing a soluble anode molten salt containing titanium), titanium white and graphite are adopted as raw materials to carry out heat treatment under the vacuum condition to prepare TiC with good conductivity_xO_yThe result of the solid solution as the anode material for electrolyzing the metallic titanium shows that the electrolytic titanium has high purity and stable current, the whole process does not use chlorine gas, only generates carbon monoxide gas which can be used as fuel, has small load on the environment, is easy to realize large-scale production, and is an important method for preparing the metallic titanium. However, TiC made by this process_xO_yThe method is required to be carried out under a high vacuum condition, the sealing property of equipment is required to be excessively high, and the compactness, the conductivity, the electrolysis current efficiency and the like of an electrode still have room for further improvement.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for preparing metallic titanium by soluble anode electrolysis of a fluorine-chlorine mixed molten salt system.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a method for preparing metallic titanium by soluble anode electrolysis, which is prepared by using a solution containing TiO₂The material and the mixture containing the C material are used as raw materials, and the TiC is prepared through the main procedures of primary grinding, primary briquetting, primary roasting, secondary grinding, secondary briquetting and secondary roasting_xO_yThe conductive ceramic adopts a pre-electrolyzed fluorine-chlorine mixed molten salt system and TiC_xO_yThe conductive ceramic is used as an anode, and a high-purity metal titanium product is prepared through the working procedures of electrolysis, washing and drying.

Preferably, the steps are as follows:

s1, grinding for the first time: will contain TiO₂The material and the C-containing material are levigated to ensure TiO during mixing₂The uniformity of the C on the spatial distribution and the activity of reaction particles are simultaneously finely ground and uniformly mixed;

s2, primary briquetting: placing the material obtained by primary grinding into a die, and pressing and forming by using a press machine to form a raw material block with good compactness, wherein the die is required to meet the requirements on the geometric shape and the size of a roasted raw material block;

s3, primary roasting: carrying out high-temperature roasting on the raw material block which is formed by pressing the primary pressing block to obtain a primary roasting product;

s4, secondary grinding: the primary roasting product is ground to form TiC with small granularity and good dispersibility_xO_yCeramic fine particles;

s5, secondary briquetting: TiC obtained by secondary grinding_xO_yPlacing the ceramic fine particles in a die, and performing secondary briquetting, wherein the die meets the requirements of the geometric shape and the size of the anode;

s6, secondary roasting: TiC obtained by secondary briquetting_xO_yThe block is roasted for the second time to obtain soluble TiC required by the electrolysis of the step S8_xO_yA conductive ceramic anode;

s7, pre-electrolysis: placing the fluorine-chlorine mixed molten salt electrolyte in a graphite crucible, pre-electrolyzing by taking graphite as an anode and a tungsten wire as a cathode in an argon atmosphere to remove inherent impurity components in the fluorine-chlorine mixed molten salt electrolyte,

s8, electrolysis: with TiC_xO_yConducting ceramic as anode and refractory metal as cathode, and electrolyzing to generate CO and CO₂Gas, metal titanium is generated at the cathode, and according to different preparation process conditions, the product can be titanium sponge or titanium powder;

s9, washing: stripping the cathode electrolysis product, and washing with pure water or dilute acid solution to remove the electrolyte in the titanium sponge;

s10, drying: and (3) carrying out low-temperature vacuum drying on the washed metal titanium to remove moisture and volatile acid in the titanium sponge or titanium powder.

Preferably, the particle size (d) of the solid phase particles after grinding is no more than 75 mu m (no less than 200 meshes) no matter the primary grinding or the secondary grinding.

Preferably, no matter the primary briquetting or the secondary briquetting can adopt a plurality of briquetting modes, and when a uniaxial static pressure mode is adopted, the axial pressure is more than or equal to 20 Mpa.

Preferably, the roasting temperature T is 1300-1550 ℃ regardless of primary roasting or secondary roasting, and the roasting time T is 1 h-6 h.

Preferably, the first roasting and the second roasting are carried out under the protection of argon without maintaining a vacuum environment.

Preferably, a mixed molten salt system of fluoride and chloride is adopted in the electrolysis, and the chloride comprises NaCl, KCl, LiCl and MgCl₂And CaCl₂One or more of the fluoride compounds comprise NaF, KF and AlF₃、Na₃AlF₆、KF、K₂Ti₄F₆And Na₂Ti₄F₆One or more of them.

Preferably, in step S7, the bipolar voltage is controlled to be 2-2.7V during pre-electrolysis; in step S8, during electrolysis, the cell voltage is controlled to be 3.0-3.5V, and the anode current density is controlled to be 0.1-1.5A/cm²The cathode current density is 0.3-2A/cm²。

Preferably, the electrolytic product can be washed by pure water or dilute acid solution after being stripped, and vacuum drying is needed after washing, wherein the drying temperature is 40-80 ℃, so that the final metallic titanium product is prepared.

Preferably, the TiO-containing compound₂The material comprises titanium white, the material containing C comprises graphite, and the high-temperature resistant metal material serving as the cathode in the step S8 comprises titanium and stainless steel.

Preferably, the first and second liquid crystal materials are,

s1, grinding for the first time: the preferred molar ratio of titanium dioxide to graphite is 1: 1.5 to 2.5.

S2, primary briquetting: when in pressing, the axial static pressure is controlled to be 20-40 MPa/cm²。

S3, primary roasting: and (4) roasting at high temperature, heating to 1500-1600 ℃, and preserving heat for 1-6 hours.

S5, secondary briquetting: the axial static pressure is controlled to be 20-40 MPa/cm²。

S6, secondary roasting: heating to 1500-1600 ℃, and preserving heat for 1-6 h.

Compared with the prior art, the invention has the following beneficial effects:

the method adopted by the invention belongs to a soluble anode electrolysis method, and is similar to USTB process, and titanium dioxide (TiO) is adopted₂) And graphite (C) are used as raw materials, a soluble anode is formed through high-temperature heat treatment, and then molten salt electrolysis is carried out to prepare the metal titanium, so that the method has the advantages of the USTB process. However, the invention makes a plurality of important improvements to the USTB process, which mainly appear as follows:

(1) the non-vacuum argon protective atmosphere is adopted, so that the requirement of preparation conditions on equipment tightness is lowered, the investment of a vacuum system is reduced, and the industrial production can be realized as soon as possible; the non-nitriding anode material and the non-nitrogen protective atmosphere are adopted, so that the reduction of the purity of the metal titanium product caused by the reaction between N and Ti in the electrolytic process is avoided.

(2) The technique of sectional grinding, sectional briquetting and sectional roasting is adopted to ensure that the space distribution of reactants is more uniform, and the TiC formed after one-time roasting is reduced_xO_yPorosity in the ceramic, increased TiC_xO_yThe welding among the ceramic particles improves the TiC_xO_yThe compactness of the anode further improves the TiC in the anode_xO_yThe purity and the anode conductivity improve the mechanical strength and the corrosion resistance of the electrode under the high-temperature electrolysis condition;

(3) compared with a simple chloride system, the fluorine-chlorine compound mixed system adopted as the electrolyte reduces the volatilization of molten salt in the electrolysis process, improves the electrolysis stability and improves the TiC_xO_ySolubility in the electrolyte, thereby contributing to an increase in current efficiency; compared with a pure fluoride system, the eutectic temperature of the electrolyte is reduced, the electrolysis temperature and energy consumption are reduced, and the operation environment is improved.

(4) Impurities in the molten salt are effectively removed through pre-electrolysis, the consumption of impurity ions to current and the precipitation of impurity ions at a cathode are reduced, and the electrolysis current efficiency and the quality of a metal titanium product are improved.

(5) TiC prepared by the technology provided by the invention_xO_yCompared with the traditional technology, the room-temperature conductivity of the anode is improved by one order of magnitude, and the high conductivity is still kept at high temperature, so that the resistance of an electrolytic loop is effectively reduced, and the current efficiency is obviously improved. Meanwhile, the compactness of the anode is enhanced, so that the stability of electrolysis is improved, and the defects that the anode is poor in stability and easy to propagate cracks and even fall off in the conventional electrolysis process are overcome.

Drawings

FIG. 1 is a flow chart of the process of the present invention, in which the TiC is prepared by milling, briquetting and roasting in stages_xO_yAnd (3) pre-electrolyzing, washing and vacuum drying the anode material at low temperature to obtain high-purity metal titanium. The roasting, pre-electrolysis and electrolysis are all carried out in the argon atmosphere.

FIG. 2 shows TiC prepared under different carbon blending amounts in the present invention_xO_yXRD pattern of anode material, from which it can be seen that when TiO is used₂The proportion of C is 1: 2 hour, prepare a single TiC_xO_yThe phase has no mixed phase and residual carbon, and the product with insufficient carbon or excessive carbon has mixed phase. Note: TiC_xO_yThe phase is a solid solution of TiC and TiO, and the diffraction peak position of the solid solution is basically consistent with that of TiC.

FIG. 3 shows TiC prepared under different carbon blending amounts in the present invention_xO_yThe XRD pattern of the anode material shows that TiC begins to form when the temperature reaches 1400 DEG C_xO_yAnd (4) phase(s). When the temperature reaches 1500 ℃, the main phase component is TiC_xO_yIncomplete reaction with residual C and Ti₂O₃A heterogeneous phase exists. When the temperature reaches 1550 ℃, single TiC is generated_xO_yAnd (4) phase(s).

FIG. 4 is TiC prepared by the present invention_xO_ySEM image of anode material, showing TiC_xO_yThe anode material presents the microscopic appearance of the coral reef with branched and porous pores. The density of the material and the thickness of bridging necks among particles can be observed according to an SEM picture, and the thickness can be used as the current in TiC during electrolysis_xO_yMesh distribution and microstructure criteria of electrical conductivity.

FIG. 5 is an XRD pattern of the titanium metal produced in accordance with the present invention, which reflects that the electrolysis product is a single titanium metal phase without any hetero-phase present under suitable electrolysis conditions.

Fig. 6 is an SEM image of the titanium metal prepared according to the present invention, which reflects that the prepared titanium metal has a dendritic structure formed by micron-sized grains, and conforms to the basic micro-morphology of titanium sponge.

Detailed Description

The technical solution of the present invention is further illustrated by the following examples.

Example 1

The embodiment relates to a method for preparing metal titanium by mixed molten salt soluble anode electrolysis, which specifically comprises the following steps (the experimental process flow is shown in figure 1):

s1, grinding for the first time: titanium dioxide and graphite are mixed according to a molar ratio of 1: 2, placing the mixture in an agate ball milling tank, and carrying out ball milling on the mixture for 3 hours on a planetary ball mill at the rotating speed of 400rpm so as to ensure TiO during material mixing₂And the homogeneity of the spatial distribution of C and the reactivity of the reactive particles.

S2, primary briquetting: placing the once ground material in a mold, pressing into cylindrical raw material block with a press, and controlling axial static pressure at 25MPa/cm²To obtain a geometric dimension of about

The raw material block of (a);

s3, primary roasting: placing the raw material block subjected to primary briquetting and compression molding in a resistance furnace for high-temperature roasting at the heating rate of 10 ℃/min to 1550 ℃, preserving heat for 4h, and cooling to obtain a primary roasting product;

s4, secondary grinding: placing the primary roasting product in an agate ball milling tank, and ball milling for 3h on a planetary ball mill at the rotating speed of 400rpm to obtain TiC with small particle size and good dispersibility_xO_yCeramic fine powder;

s5, secondary briquetting: TiC obtained by secondary grinding_xO_yPlacing ceramic powder in a die, performing secondary briquetting, and controlling axial static pressure at 25MPa/cm²TiC with a geometry of about 50mm 15mm 5mm is obtained_xO_yAnd (3) material blocks.

S6, secondary roasting: TiC obtained by secondary briquetting_xO_yThe material block is placed in a resistance furnace for secondary roasting, the heating rate is still 10 ℃/min, the temperature is raised to 1550 ℃, the temperature is preserved for 4h, and the soluble TiC required by electrolysis is obtained_xO_yThe XRD of the anode block (the product is shown by G2 curve in fig. 2 and S7(1823K) curve in fig. 3), and the microscopic morphology of the product is shown in fig. 4);

s7, pre-electrolysis: the fluorine-chlorine mixed molten salt electrolyte is placed in a graphite crucible, and pre-electrolysis is carried out under the argon atmosphere by taking graphite as an anode and taking a tungsten wire as a cathode so as to remove inherent impurity components in the molten salt. The cell voltage during pre-electrolysis was controlled at 2.6V.

S8, electrolysis: with TiC_xO_yThe anode block is used as an anode, the titanium sheet is used as a cathode, and KCl-NaCl-K is used₂TiF₆The mixed molten salt is used as electrolyte for electrolysis, the cell voltage is controlled at 3.0V, and the anode current density is about 0.2A/cm²And the cathode current density is in the range of 0.3A/cm². CO and CO are produced at the anode during electrolysis₂The gas precipitates metallic titanium at the cathode.

S9, washing: after stripping the electrolysis product, washing the electrolysis product with a dilute hydrochloric acid solution with the concentration of 3% and then washing the electrolysis product with pure water to remove the electrolyte in the titanium sponge.

S10, drying: and after washing, putting the obtained metallic titanium into a vacuum drying oven for vacuum drying at the drying temperature of 40 ℃ for 6 hours to remove water in the titanium sponge and hydrochloric acid in residual washing liquid, thereby preparing a final metallic titanium product (the XRD is shown in figure 5, and the SEM is shown in figure 6).

TiC prepared by the process steps_xO_yThe conductivity of the anode at 768.21 deg.C is 1.06X 10⁵S·m^-1The current efficiency reaches 90.32%, the purity of the obtained metal titanium product is 99.92%, and the specific chemical components are shown in table 1:

TABLE 1 titanium sponge product chemistry (mass%) prepared by EXAMPLE 1

Example 2

The embodiment relates to a method for preparing metal titanium by mixed molten salt soluble anode electrolysis, which specifically comprises the following steps:

s1, grinding for the first time: titanium dioxide and graphite are mixed according to a molar ratio of 1: 2, placing the mixture in an agate ball milling tank, and carrying out ball milling on the mixture for 6 hours on a planetary ball mill at the rotating speed of 300rpm so as to ensure TiO during material mixing₂And the homogeneity of the spatial distribution of C and the reactivity of the reactive particles.

S2, primary briquetting: placing the once ground material in a mold, pressing into cylindrical raw material block with a press, and controlling axial static pressure at 30MPa/cm²To obtain a geometric dimension of about

The raw material block of (a);

s3, primary roasting: placing the raw material block which is formed by pressing the primary briquetting into a resistance furnace for high-temperature roasting at the heating rate of 10 ℃/min to 1600 ℃ under the argon atmosphere, preserving the heat for 2h, and cooling to obtain a primary roasting product;

s4, secondary grinding: placing the primary roasting product in an agate ball milling tank, and ball milling for 6h on a planetary ball mill at the rotating speed of 300rpm to obtain TiC with small particle size and good dispersibility_xO_yCeramic fine powder;

s5, secondary briquetting: TiC obtained by secondary grinding_xO_yPlacing ceramic powder in a die, performing secondary briquetting, and controlling axial static pressure at 30MPa/cm²TiC with a geometry of about 50mm 15mm 5mm is obtained_xO_yAnd (3) material blocks.

S6, secondary roasting: TiC obtained by secondary briquetting_xO_yThe material block is placed in a resistance furnace for secondary roasting, the heating rate is still 10 DEG CMin, heating to 1600 ℃, and preserving heat for 4h to obtain soluble TiC required by electrolysis_xO_yAn anode block;

s7, pre-electrolysis: the fluorine-chlorine mixed molten salt electrolyte is placed in a graphite crucible, and pre-electrolysis is carried out under the argon atmosphere by taking graphite as an anode and taking a tungsten wire as a cathode so as to remove inherent impurity components in the molten salt. The cell voltage during pre-electrolysis was controlled at 2.7V.

S8, electrolysis: with TiC_xO_yThe anode block is used as an anode, the titanium sheet is used as a cathode, and KCl-NaCl-K is used₂TiF₆The mixed molten salt is used as electrolyte for electrolysis, the cell voltage is controlled at 3.0V, and the anode current density is about 0.3A/cm²And the cathode current density is in the range of 0.5A/cm². CO and CO are produced at the anode during electrolysis₂The gas precipitates metallic titanium at the cathode.

S10, drying: and (3) after washing, placing the obtained metallic titanium in a vacuum drying oven for vacuum drying at the drying temperature of 50 ℃ for 4 hours to remove water in the titanium sponge and hydrochloric acid in the residual washing liquid, thereby preparing the final metallic titanium product.

TiC prepared by the process steps_xO_yThe conductivity of the anode at 768.21 ℃ is 1.24X 10⁵S·m^-1The current efficiency reaches 90.17%, and the purity of the obtained metal titanium product is 99.90%.

Example 3

s1, grinding for the first time: titanium dioxide and graphite are mixed according to a molar ratio of 1: 2, placing the mixture in an agate ball milling tank, and carrying out ball milling on the mixture for 5 hours on a planetary ball mill at the rotating speed of 400rpm so as to ensure TiO during material mixing₂And the homogeneity of the spatial distribution of C and the reactivity of the reactive particles.

S2, primary briquetting: placing the once ground material in a mold, and pressingPressing into cylindrical raw material block with axial static pressure controlled at 40MPa/cm²To obtain a geometric dimension of about

The raw material block of (a);

s3, primary roasting: placing the raw material block subjected to primary briquetting and compression molding in a resistance furnace for high-temperature roasting at the heating rate of 10 ℃/min to 1550 ℃, preserving heat for 2 hours, and cooling to obtain a primary roasting product;

s5, secondary briquetting: TiC obtained by secondary grinding_xO_yPlacing ceramic powder in a die, performing secondary briquetting, and controlling axial static pressure at 20MPa/cm²TiC with a geometry of about 50mm 15mm 5mm is obtained_xO_yAnd (3) material blocks.

S6, secondary roasting: TiC obtained by secondary briquetting_xO_yThe material block is placed in a resistance furnace for secondary roasting, the heating rate is still 10 ℃/min, the temperature is raised to 1600 ℃, the temperature is preserved for 3h, and the soluble TiC required by electrolysis is obtained_xO_yAn anode block;

s7, pre-electrolysis: the fluorine-chlorine mixed molten salt electrolyte is placed in a graphite crucible, and pre-electrolysis is carried out under the argon atmosphere by taking graphite as an anode and taking a tungsten wire as a cathode so as to remove inherent impurity components in the molten salt. The cell voltage during pre-electrolysis was controlled at 2.5V.

S8, electrolysis: with TiC_xO_yThe anode block is used as an anode, the titanium sheet is used as a cathode, and KCl-NaCl-K is used₂TiF₆The mixed molten salt is used as electrolyte for electrolysis, the cell voltage is controlled at 3.3V, and the anode current density is about 0.4A/cm²And the cathode current density is in the range of 0.8A/cm². CO and CO are produced at the anode during electrolysis₂The gas precipitates metallic titanium at the cathode.

S9, washing: after stripping the electrolysis product, washing the electrolysis product with a 1% dilute hydrochloric acid solution, and then washing the electrolysis product with pure water to remove the electrolyte in the titanium sponge.

S10, drying: and (3) after washing, placing the obtained metal titanium in a vacuum drying oven for vacuum drying at the drying temperature of 70 ℃ for 2 hours to remove water in the titanium sponge and hydrochloric acid in the residual washing liquid, thereby preparing the final metal titanium product.

TiC prepared by the process steps_xO_yThe conductivity of the anode at 768.21 deg.C is 0.95 × 10⁵S·m^-1The current efficiency reaches 90.38%, and the purity of the obtained metal titanium product is 99.91%.

Example 4

s1, grinding for the first time: titanium dioxide and graphite are mixed according to a molar ratio of 1: 2, placing the mixture in an agate ball milling tank, and carrying out ball milling on the mixture for 8 hours on a planetary ball mill at the rotating speed of 350rpm so as to ensure TiO during material mixing₂And the homogeneity of the spatial distribution of C and the reactivity of the reactive particles.

S2, primary briquetting: placing the once ground material in a mold, pressing into cylindrical raw material block with a press, and controlling axial static pressure at 35MPa/cm²To obtain a geometric dimension of about

The raw material block of (a);

s3, primary roasting: placing the raw material block subjected to primary briquetting and compression molding in a resistance furnace for high-temperature roasting at the heating rate of 10 ℃/min to 1525 ℃, preserving heat for 5h, and cooling to obtain a primary roasting product;

S6, secondary roasting: TiC obtained by secondary briquetting_xO_yThe material block is placed in a resistance furnace for secondary roasting, the temperature rise rate is still 10 ℃/min, the temperature is raised to 1525 ℃, the temperature is preserved for 3h, and the soluble TiC required by electrolysis is obtained_xO_yAn anode block;

S8, electrolysis: with TiC_xO_yThe anode block is used as an anode, the titanium sheet is used as a cathode, and KCl-NaCl-K is used₂TiF₆The mixed molten salt is used as electrolyte for electrolysis, the cell voltage is controlled to be 3.1V during the electrolysis, and the anode current density is about 0.3A/cm²And the cathode current density is in the range of 0.6A/cm². CO and CO are produced at the anode during electrolysis₂The gas precipitates metallic titanium at the cathode.

S9, washing: after stripping the electrolysis product, washing the electrolysis product with 2% dilute hydrochloric acid solution, and then washing the electrolysis product with pure water to remove the electrolyte in the titanium sponge.

TiC prepared by the process steps_xO_yThe conductivity of the anode at 768.21 ℃ is 1.67X 10⁵S·m^-1The current efficiency reaches 89.23 percent, and the purity of the obtained metal titanium product is 99.87 percent.

Comparative examples

The embodiment relates to a method for preparing metallic titanium by traditional soluble anode electrolysis, which comprises the following preparation process conditions: the method for preparing the metallic titanium only by one-time grinding, one-time briquetting and one-time roasting process is carried out in a vacuum environment, the electrolyte is a KCl-NaCl chloride system and does not undergo pre-electrolysis, the other preparation conditions are completely the same as those of the embodiment 1, and the specific steps are as follows:

s1, grinding: titanium dioxide and graphite are mixed according to a molar ratio of 1: 2, placing the mixture in an agate ball milling tank, and carrying out ball milling on the mixture for 3 hours on a planetary ball mill at the rotating speed of 400rpm so as to ensure TiO during material mixing₂And the homogeneity of the spatial distribution of C and the reactivity of the reactive particles.

S2, briquetting: placing the once ground material in a mold, pressing into cylindrical raw material block with a press, and controlling axial static pressure at 25MPa/cm²To obtain a geometric dimension of about

The raw material block of (a);

s3, roasting: under the vacuum condition (the vacuum pressure is about 70 Pa), placing the raw material block which is formed by pressing into a resistance furnace for high-temperature roasting, wherein the heating rate is 10 ℃/min, the temperature is increased to 1550 ℃, the temperature is kept for 4h, and the TiC is obtained after cooling_xO_yAn anode block;

s4, electrolysis: with TiC_xO_yThe anode block is used as an anode, a titanium sheet is used as a cathode, KCl-NaCl chloride fused salt is used as electrolyte for electrolysis, and the current density of the anode is about 0.2A/cm²And the cathode current density is in the range of 0.3A/cm². CO and CO are produced at the anode during electrolysis₂The gas precipitates metallic titanium at the cathode.

S5, washing: after stripping the electrolysis product, washing the electrolysis product with a dilute hydrochloric acid solution with the concentration of 3% and then washing the electrolysis product with pure water to remove the electrolyte in the titanium sponge.

S6, drying: and (3) after washing, placing the obtained metallic titanium in a vacuum drying oven for vacuum drying at the drying temperature of 40 ℃ for 6 hours to remove water in the titanium sponge and hydrochloric acid in the residual washing liquid, thereby preparing the final metallic titanium product.

TiC prepared by the process steps_xO_yThe anode had a conductivity of 0.72X 10 at room temperature⁴S·m^-1The current efficiency reaches 84.46%, and the purity of the obtained metal titanium product is 99.05%.

As can be seen from the comparison of the examples and the comparative examples, although the technological process of the method adopted by the invention is longer than that of the prior soluble anode electrolysis preparation of metallic titanium, the experimental result shows that TiC is prepared after the improvement of the process of the invention_xO_yThe conductivity of the anode is improved by more than one order of magnitude, the current efficiency is improved by about 5-6%, and the purity of the metallic titanium product is improved from 2N level to 3N level, so that the method has a vital effect on reducing production energy consumption and improving the product grade, and has a good promotion effect on the industrial production of preparing the metallic titanium by an electrolytic method.

Claims

1. a method for preparing metal titanium by fluorine-chlorine mixed molten salt system soluble anode electrolysis, it is characterized in that, with the mixture of containing TiO ₂ material and containing C material as raw material, through a grinding, a briquetting, a roasting, The main processes of secondary grinding, secondary briquetting and secondary roasting prepare TiC _x O _y conductive ceramics, adopt the fluorine-chlorine mixed molten salt system after pre-electrolysis, take TiC _x O _y conductive ceramics as anodes, and undergo electrolysis. , washing and drying process to prepare high-purity metal titanium products.

2. the method for preparing metallic titanium by fluorine-chlorine mixed molten salt system soluble anode electrolysis according to claim 1, is characterized in that, described each step is as follows:

S1. One-time grinding: The TiO ₂ -containing material and the C-containing material are ground to ensure the uniformity of the spatial distribution of TiO ₂ and C and the activity of the reaction particles during mixing, and the one-time grinding has both a mixing effect;

S2. One-time briquetting: place the material obtained by one-time grinding in a mold, and press it with a press to form a green block with good compactness. The mold used should meet the geometric shape and size requirements of the roasted raw block;

S3, one-time roasting: carry out high-temperature roasting to the raw block of one-time briquetting pressing to obtain a roasting product;

S4. Secondary grinding: After the primary calcination product is ground, fine ceramic particles of TiC _x O _y with small particle size and good dispersibility are formed;

S5. Secondary briquetting: The TiC _x O _y ceramic fine particles obtained by secondary grinding are placed in a mold for secondary briquetting, and the mold used should meet the requirements of the geometry and size of the anode;

S6, secondary roasting: secondary roasting is carried out to the TiC _x O _y block obtained from the secondary briquetting to obtain the soluble TiC _x O _y conductive ceramic anode required for the electrolysis in step S8;

S7. Pre-electrolysis: Put the fluorine-chlorine mixed molten salt electrolyte in a graphite crucible, and in an argon atmosphere, use graphite as the anode and tungsten wire as the cathode to perform pre-electrolysis to remove the inherent in the fluorine-chlorine mixed molten salt electrolyte. impurity components,

S8. Electrolysis: use TiC _x O _y conductive ceramics as the anode and high temperature resistant metal materials as the cathode to conduct electrolysis. During electrolysis, CO and CO ₂ gases are generated at the anode, and metal titanium is generated at the cathode. According to the different preparation process conditions, The product can be titanium sponge or titanium powder;

S9, washing: after stripping the cathode electrolysis product, wash with pure water or dilute acid solution to remove the electrolyte in the sponge titanium;

S10. Drying: The metal titanium obtained after washing needs to be dried in a low-temperature vacuum to remove moisture and volatile acid in sponge titanium or titanium powder.

3. the method for preparing metallic titanium by fluorine-chlorine mixed molten salt system soluble anode electrolysis according to claim 1 and 2, it is characterized in that, no matter primary grinding or secondary grinding, the solid phase particle size d after grinding should satisfy d≤75μm.

4. the method for preparing metallic titanium by fluorine-chlorine mixed molten salt system soluble anode electrolysis according to claim 1 and 2, it is characterized in that, no matter primary briquetting or secondary briquetting, can adopt various briquetting methods, When the uniaxial static pressure method is adopted, the axial pressure is greater than or equal to 20Mpa.

5. the method for preparing metallic titanium by the soluble anode electrolysis of fluorine-chlorine mixed molten salt system according to claim 1 and 2, it is characterized in that, no matter for primary roasting or secondary roasting, roasting temperature T needs to satisfy 1300≤T≤1550 ℃, the roasting time t is 1h≤t≤6h.

6. the method for preparing metallic titanium by the soluble anode electrolysis of fluorine-chlorine mixed molten salt system according to claim 1 and 2, it is characterized in that, no matter it is primary roasting or secondary roasting without keeping vacuum environment, all in argon protective atmosphere proceed below.

7. the method for preparing metal titanium by soluble anode electrolysis of fluorine-chlorine mixed molten salt system according to claim 1 and 2, is characterized in that, adopts fluoride and chloride mixed molten salt system during electrolysis, and described chloride comprises NaCl One or more of , KCl, LiCl, MgCl ₂ and CaCl ₂ , the fluorides include NaF, KF, AlF ₃ , Na ₃ AlF ₆ , KF, K ₂ Ti ₄ F ₆ and Na ₂ Ti ₄ F ₆ one or more of them.

8. The method for preparing metal titanium by soluble anode electrolysis of fluorine-chlorine mixed molten salt system according to claim 1 or 2, characterized in that, in step S7, during pre-electrolysis, the voltage of both poles is controlled at 2-2.7V; step S8 During electrolysis, the cell voltage is controlled at 3.0-3.5V, the anode current density is in the range of 0.1-1.5A/cm ² , and the cathode current density is in the range of 0.3-2A/cm ² .

9. the method for preparing metallic titanium by the soluble anode electrolysis of fluorine-chlorine mixed molten salt system according to claim 1 and 2, it is characterized in that, can adopt pure water or dilute acid solution to wash after the electrolysis product is peeled off, need to carry out after washing Vacuum drying, the drying temperature should be 40-80 ℃, so as to prepare the final metal titanium product.

10. The method for preparing metal titanium by soluble anode electrolysis of a fluorine-chlorine mixed molten salt system according to claim 1 or 2, wherein the _TiO2 -containing material comprises titanium white, the C-containing material comprises graphite, and the The high temperature-resistant metal materials used as the cathode in the step S8 include titanium and stainless steel.