Device and method for preparing high-purity titanium powder by continuous electrolysis

Abstract

A device and method for preparing high-purity titanium powder by continuous electrolysis are provided. The method includes: electrolyzing a titanium-containing conductive ceramic anode and a rotatable cathode in a fused salt electrolytic tank; continuously transferring titanium powder deposited on a surface of the cathode by the rotatable cathode to a position above the fused salt; scraping the titanium powder by a discharging scraper, and collecting; filtering the titanium powder, and recovering the fused salt; cooling separated titanium powder, washing with deoxygenated and deionized water, and vacuum-drying to obtain final titanium powder. The device includes a fused salt electrolysis mechanism, a continuous titanium powder collection mechanism, a filtering mechanism, a washing mechanism, and a vacuum-drying mechanism.

Claims

1. A device for preparing high-purity titanium powder by continuous electrolysis, comprising a continuous electrolysis discharging mechanism, a filtering mechanism, a washing mechanism, and a drying mechanism, wherein the continuous electrolysis discharging mechanism comprises an electrolytic tank body; at least one titanium-containing conductive ceramic anode and a rotatable cathode are provided inside the electrolytic tank body, wherein the at least one titanium-containing conductive ceramic anode is prepared by the following steps: mixing and grinding TiO.sub.2 with an average particle size of 0.4 μm and a purity of 99% and graphite powder with an average particle size of 50 μm and a purity of 99.8% at a mass ratio of 8:2 for 2 h to 3 h in a ball mill to obtain a first resulting mixture, pressing the first resulting mixture into particles with a diameter of 10 mm to 12 mm and a height of 10 mm to 12 mm under a pressure of 50 MPa to 60 MPa in a steel mold, treating the particles at 1,000° C. to 1,500° C. in an argon atmosphere or a nitrogen and argon atmosphere for 2 h to 18 h to obtain a titanium-containing conductive ceramic, mixing and grinding the titanium-containing conductive ceramic and water in the ball mill to obtain a second resulting mixture, and subjecting the second resulting mixture to press-molding in a mold and then to sintering at 1.600° C. to 1.800° C. in the argon atmosphere to obtain the at least one titanium-containing conductive ceramic anode; a lower space below a top of the at least one titanium—containing conductive ceramic anode—in the electrolytic tank body is a fused salt chamber configured to hold a fused salt, and the remaining upper space is an inert atmosphere/vacuum environment chamber; one end of the rotatable cathode extends into the inert atmosphere/vacuum environment chamber; a side of the rotatable cathode located in the inert atmosphere/vacuum environment chamber—is provided with an automatic discharging mechanism, and the automatic discharging mechanism communicates with an inert atmosphere/vacuum environment storage tank provided outside the electrolytic tank body; titanium powder deposited at the rotatable cathode is continuously transferred to the inert atmosphere/vacuum environment chamber, discharged by the automatic discharging mechanism, and then sent to and stored in the inert atmosphere/vacuum environment storage tank; a top of the electrolytic tank body is sealed by an electrolytic tank sealing cover; the device further comprises a power source, wherein the power source is electrically connected with the at least one titanium-containing conductive ceramic anode and the rotatable cathode.

2. The device according to claim 1, wherein the rotatable cathode is a conveyor belt, comprising a driving pulley provided in the inert atmosphere/vacuum environment chamber, a driven pulley at a lower part of the electrolytic tank body, and a belt-shaped cathode sleeved between the driving pulley and the driven pulley; a driving end of the driving pulley is coupled with an output shaft of a driving motor, and the driving motor is electrically connected to the power source; and the at least one titanium-containing conductive ceramic anode is two titanium-containing conductive ceramic anodes oppositely provided at two sides of the rotatable cathode.

3. The device according to claim 1, wherein the rotatable cathode is a roller, comprising a driving motor, a roller shaft provided between the fused salt chamber and the inert atmosphere/vacuum environment chamber, and a roller cathode sleeved on the roller shaft; a driving end of the roller shaft is coupled with an output shaft of the driving motor, and the driving motor is electrically connected to the power source; and the at least one titanium-containing conductive ceramic anode is in an arc shape adaptive to the roller cathode.

4. The device according to claim 1, wherein the automatic discharging mechanism comprises a discharging scrape, a discharging hopper, and a discharging pipe; the discharging scraper is provided obliquely and oppositely relative to an outer wall of the rotatable cathode at a given spacing; the discharging hopper is located at a position where the titanium powder falls; a bottom of the discharging hopper communicates with the inert atmosphere/vacuum environment storage tank-through the discharging pipe; and the discharging scraper is tangential to the outer wall of the rotatable cathode.

5. A method for preparing high-purity titanium powder by continuous electrolysis based on the device according to claim 1, comprising the following steps: S1. fused salt electrolysis: energizing the at least one titanium-containing conductive ceramic anode and the rotatable cathode in the electrolytic tank body with the fused salt for electrolysis, wherein the at least one titanium-containing conductive ceramic anode has a chemical composition of TiC.sub.xO.sub.y (0<x≤y≤1, x+y=1) or TiC.sub.xO.sub.yN.sub.z (0<x≤y≤1, 0<z<1,x+y+z=1); S2. continuous extraction of titanium powder: continuously transferring the titanium powder reduced and deposited on a surface of the rotatable cathode to a position above the fused salt through periodic rotation movement of the rotatable cathode, and scraping the titanium powder by the automatic discharging mechanism to continuously collect scraped titanium powder, wherein the scraped titanium powder admixed with the fused salt enters the storage tank under gravity; S3. titanium powder separation and fused salt recovery: passing the scraped titanium powder admixed with the fused salt through the filtering mechanism to obtain filtered titanium powder, and recovering the fused salt; S4. washing by the washing mechanism: after the filtered titanium powder is cooled, washing the filtered titanium powder with deoxygenated and deionized water to remove residual fused salt; and S5. vacuum-drying by the drying mechanism: vacuum-drying to obtain final titanium powder.

6. The method according to claim 5, wherein during the fused salt electrolysis in S1, a current density at the rotatable cathode is adjusted to control an average particle size of prepared high-purity titanium powder; the rotatable cathode has a current density range of 0.05 A/cm.sup.2 to 1.2 A/cm.sup.2, and the titanium powder has an average particle size range of 0.7 μm to 2 mm.

7. The method according to claim 5, wherein in S2, the surface of the rotatable cathode deposited with titanium powder is made of one or more from the group consisting of titanium, titanium alloy, carbon steel, stainless steel, aluminum, aluminum alloy, chromium, molybdenum, magnesium, and copper.

8. The method according to claim 5, wherein in S1, the fused salt comprises one or more from the group consisting of LiCl, NaCl, KCl, MgCl.sub.2, and CaCl.sub.2; a sum of Ti.sup.2+ and Ti.sup.3+ concentrations is less than 8% wt; and the fused salt electrolysis is conducted at 420° C. to 750° C.

9. The method according to claim 5, wherein in S2, the periodic rotation movement of the rotatable cathode relative to the at least one titanium-containing conductive ceramic anode is at a relative movement rate of 0 m/s to 2.5 m/s, and as the movement rate increases, the average particle size of the titanium powder decreases correspondingly; and the titanium powder has an average particle size range of 0.7 μm to 2 mm.

10. The method according to claim 5, wherein in S3, the filtering mechanism is placed in an inert atmosphere or a vacuum environment at a temperature of 420° C. to 750° C.; and in S5, the final titanium powder has an oxygen content of less than 0.3% wt, a carbon content of less than 0.1% wt, and an iron content of less than 0.4% wt.

11. The method according to claim 5, wherein the rotatable cathode is a conveyor belt, comprising a driving pulley provided in the inert atmosphere/vacuum environment chamber, a driven pulley at a lower part of the electrolytic tank body, and a belt-shaped cathode sleeved between the driving pulley and the driven pulley; a driving end of the driving pulley is coupled with an output shaft of a driving motor, and the driving motor is electrically connected to the power source; and the at least one titanium-containing conductive ceramic anode is two titanium-containing conductive ceramic anodes oppositely provided at two sides of the rotatable cathode.

12. The method according to claim 5, wherein the rotatable cathode is a roller, comprising a driving motor, a roller shaft provided between the fused salt chamber and the inert atmosphere/vacuum environment chamber, and a roller cathode sleeved on the roller shaft; a driving end of the roller shaft is coupled with an output shaft of the driving motor, and the driving motor is electrically connected to the power source; and the at least one titanium-containing conductive ceramic anode is in an arc shape adaptive to the roller cathode.

13. The method according to claim 5, wherein the automatic discharging mechanism comprises a discharging scraper, a discharging hopper, and a discharging pipe; the discharging scraper is provided obliquely and oppositely relative to an outer wall of the rotatable cathode at a given spacing; the discharging hopper is located at a position where the titanium powder falls; a bottom of the discharging hopper communicates with the inert atmosphere/vacuum environment storage tank through the discharging pipe; and the discharging scraper is tangential to the outer wall of the rotatable cathode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram illustrating the device for preparing high-purity titanium powder by continuous electrolysis that is equipped with a conveyor-belt-type rotatable cathode; and

(2) FIG. 2 is a schematic diagram illustrating the device for preparing high-purity titanium powder by continuous electrolysis that is equipped with a roller-type rotatable cathode.

(3) In the figures: 1 represents a titanium-containing conductive ceramic anode, 2 represents a cathode, 3 represents a fused salt chamber, 4 represents an electrolytic tank body, 5 represents an electrolytic tank sealing cover, 6 represents a driving pulley, 7 represents a driven pulley, 8 represents an inert atmosphere/vacuum environment chamber, 9 represents a discharging scraper, 10 represents titanium powder, 11 represents a discharging hopper, 12 represents a discharging pipe, 13 represents a storage tank, and 14 represents a roller cathode.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) The examples of the present disclosure are described in detail below, but the present disclosure can be implemented in various different modes limited and involved by the claims.

(5) In an example, a titanium-containing conductive ceramic anode is prepared. There are various methods for preparing the titanium-containing conductive ceramic anode. The titanium-containing conductive ceramic anode used in the examples of the present disclosure is prepared by the following method: titanium dioxide (with an average particle size of 0.4 μm and 99% of TiO.sub.2) and graphite powder (with an average particle size of 50 μm and a carbon content of 99.8%) are mixed and ground at a mass ratio of 8:2 for 2 h to 3 h in a ball mill, and a resulting mixture is pressed into particles with a diameter of 10 mm to 12 mm and a height of 10 mm to 12 mm under a pressure of 50 MPa to 60 MPa in a steel mold; the particles are treated at 1,000° C. to 1,500° C. in an argon atmosphere or a nitrogen and argon atmosphere for 2 h to 18 h to obtain a titanium-containing conductive ceramic with a chemical composition of TiC.sub.xO.sub.y (0<x≤y≤1, x+y=1) or TiC.sub.xO.sub.yN.sub.z (0<x≤y≤1, 0<z<1, x+y+z=1), where the chemical composition is determined by XRD analysis; and the titanium-containing conductive ceramic and water are mixed and ground in a ball mill, and a resulting mixture is subjected to press-molding in a mold and then to sintering at 1,600° C. to 1,800° C. in an argon atmosphere to obtain the titanium-containing conductive ceramic anode.

(6) The device for preparing high-purity titanium powder by continuous electrolysis according to the present disclosure includes a continuous electrolysis discharging mechanism, a filtering mechanism, a washing mechanism, and a drying mechanism, where the continuous electrolysis discharging mechanism includes an electrolytic tank body 4 and a power source; at least one titanium-containing conductive ceramic anode 1 and a rotatable cathode 2 are provided inside the electrolytic tank body 4; a lower space below a top of the titanium-containing conductive ceramic anode in the electrolytic tank body 4 is a fused salt chamber 3 configured to hold a fused salt, and the remaining upper space is an inert atmosphere/vacuum environment chamber 8; one end of the cathode 2 extends into the inert atmosphere/vacuum environment chamber 8; a side of the cathode 2 located in the inert atmosphere/vacuum environment chamber 8 is provided with an automatic discharging mechanism, and the automatic discharging mechanism communicates with a storage tank 13 provided outside the electrolytic tank body 4; titanium powder deposited at the cathode 2 is continuously transferred to the inert atmosphere/vacuum environment chamber 8, discharged by the automatic discharging mechanism, and then sent to and stored in the storage tank 13; a top of the electrolytic tank body 4 is sealed by an electrolytic tank sealing cover 5; and the power source is electrically connected with the titanium-containing conductive ceramic anode 1 and the cathode 2.

(7) As shown in FIG. 1, the rotatable cathode may be provided in the form of a conveyor belt, including a driving pulley 6 provided in the inert atmosphere/vacuum environment chamber 8, a driven pulley 7 at a lower part of the electrolytic tank body 4, and a belt-shaped cathode sleeved between the driving pulley and the driven pulley; a driving end of the driving pulley 6 may be coupled with an output shaft of a driving motor, and the driving motor may be electrically connected to the power source; and there may be two titanium-containing conductive ceramic anodes 1 oppositely provided at two sides of the cathode 2. The cathode 2 may be made of titanium, stainless steel, or the like, and may be connected to a negative electrode of the power supply through the driving pulley 6. As an equivalent solution, as shown in FIG. 2, the rotatable cathode 2 may be provided in the form of a roller, including a driving motor, a roller shaft provided between the fused salt chamber 3 and the inert atmosphere/vacuum environment chamber 8, and a roller cathode sleeved on the roller shaft; a driving end of the roller shaft may be coupled with an output shaft of the driving motor, and the driving motor may be electrically connected to the power source; and the titanium-containing conductive ceramic anode 1 may be in an arc shape adaptive to the roller cathode. It is ensured that distances between the anode and the cathode in the two cases are the same.

(8) In the present disclosure, the automatic discharging mechanism may include a discharging scraper 9, a discharging hopper 11, and a discharging pipe 12; the discharging scraper 9 may be provided tangentially to an outer wall of the cathode 2 at a given spacing; the discharging hopper 11 may be located at a position where the titanium powder 10 falls; and a bottom of the discharging hopper 11 may communicate with the storage tank 13 through the discharging pipe 12.

(9) In the example, after the electrolysis is completed, the titanium powder at an inner bottom of the storage tank 13 is passed through a suction filtration mechanism in an argon atmosphere, where a titanium mesh filter layer is used to separate the titanium powder under heat preservation conditions; the fused salt is recovered and returned to the electrolytic tank; then the titanium powder obtained from the filtration is cooled to below 80° C., and washed 4 times with deoxygenated and deionized water in a stirred tank to remove a small amount of residual inorganic salt; and the titanium powder is dried under vacuum to obtain final titanium powder.

Example 1

(10) The fused salt electrolysis device equipped with a conveyor-belt-type rotatable cathode shown in FIG. 1 was used, where a titanium-containing conductive ceramic anode 1 with a chemical composition of TiC.sub.0.33O.sub.0.67 prepared by the above method was selected. The belt-shaped cathode 2 was made of SUS304 stainless steel, with a thickness of 0.5 mm. The LiCl—NaCl—KCl—TiCl.sub.2—TiCl.sub.3 fused salt was used as an electrolyte, with a titanium ion content of 4% wt. The inert atmosphere chamber 8 in the electrolytic tank was protected by argon, and electrolysis was conducted at 550° C. The electrolytic tank had a voltage of 4.1 V, and the current density at the cathode was 0.3 A/cm.sup.2. The belt-shaped cathode had a rotation rate of 0.2 m/s. After electrolysis was conducted for 12 h, the titanium powder at the bottom of the storage tank 13 was passed through a titanium mesh filtering mechanism, and the fused salt was recovered. Then the titanium powder obtained from the filtration was cooled to below 80° C. and washed with deoxygenated and deionized water. Finally, the titanium powder was dried under vacuum conditions to obtain titanium powder.

(11) The obtained titanium powder had an average particle size of 43 μm, and elemental analysis results of the titanium powder were as follows: Ti: 99.30%, C: 0.07%, O: 0.25%, and Fe: 0.26%. A yield of Ti was 96%, and the current efficiency of the cathode was 84%.

Examples 2 to 6

(12) The experimental conditions in these examples were the same as in Example 1 except that a rotation rate of the belt-shaped cathode was changed. The average particle size of obtained titanium powder was as follows:

(13) TABLE-US-00001 Rotation rate of rotatable Average particle size of titanium Example cathode (m/s) powder (μm) 2 0.05 487 3 0.1 135 4 0.5 30 5 1 13 6 2 3.5

Example 7

(14) The fused salt electrolysis device equipped with a conveyor-belt-type rotatable cathode shown in FIG. 1 was used, where a titanium-containing conductive ceramic anode with a chemical composition of TiC.sub.0.2O.sub.0.4N.sub.0.4 was selected. The conveyor-belt-type rotatable cathode was a Ti metal belt with a thickness of 0.3 mm. The Ca.sub.2Cl—NaCl—KCl—TiCl.sub.2 fused salt was used as an electrolyte, with a titanium ion content of 3% wt. Electrolysis was conducted at 670° C. The electrolytic tank had a voltage of 3.6 V, and the current density at the cathode was 0.1 A/cm.sup.2. The other experimental conditions were the same as in Example 1.

(15) The obtained titanium powder had an average particle size of 55 μm, and elemental analysis results of the titanium powder were as follows. Ti: 99.50%, C: 0.05%, O: 0.15%, and Fe: 0.07%. A yield of Ti was 97%, and the current efficiency of the cathode was 91%.

Example 8

(16) The fused salt electrolysis device equipped with a roller-type rotatable cathode shown in FIG. 2 was used, where a titanium-containing conductive ceramic anode 1 with a chemical composition of TiC.sub.0.3O.sub.0.5N.sub.0.2 was selected. The rotatable cathode 2 on the surface of the roller was made of SUS316 stainless steel, with a thickness of 1 mm. The LiCl—NaCl—MgCl.sub.2—TiCl.sub.2—TiCl.sub.3 fused salt was used as an electrolyte, with a titanium ion content of 5% wt. The chamber 8 in the electrolytic tank was in a vacuum environment, and electrolysis was conducted at 570° C. The electrolytic tank had a voltage of 4.7 V, and the current density at the cathode was 0.4 A/cm.sup.2. The roller-type rotatable cathode 14 had a rotation rate of 10 rpm. After electrolysis was conducted for 12 h, the titanium powder in the storage tank 13 was passed through a titanium mesh filtering mechanism, and the fused salt was recovered. Then the titanium powder obtained from the filtration was cooled to below 80° C. and washed with deoxygenated and deionized water. Finally, the titanium powder was dried under vacuum conditions to obtain titanium powder.

(17) The obtained titanium powder had an average particle size of 16 μm, and elemental analysis results of the titanium powder were as follows: Ti: 99.50%, C: 0.08%, O: 0.13%, and Fe: 0.21%. A yield of Ti was 96%, and the current efficiency of the cathode was 97%.

Examples 9 to 12

(18) The experimental conditions in these examples were the same as in Example 8 except that the current density of the roller-type rotatable cathode was changed. The average particle size of obtained titanium powder was as follows:

(19) TABLE-US-00002 Current density Average particle size of Example (A/cm.sup.2) titanium powder (μm) 9 0.05 145 10 0.2 83 11 0.6 4.2 12 0.8 2

(20) The above examples are merely preferred examples of the present disclosure and are not intended to limit the present disclosure, and various changes and modifications may be made to the present disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements and the like made within the spirit and principles of the present disclosure are intended to be included in the protection scope of the present disclosure.