JPH07252550A - Production of titanium - Google Patents

Abstract

PURPOSE:To separate Ti from a by-product and to produce a highquality Ti ingot by placing a mixture of the Ti obtained by the reaction of TiCl4 with the reducing metal and the by-product into the crucible with the upper and lower ends opened and heating the mixture. CONSTITUTION:Mg as a reducing agent is put in the reaction vessel 12 in a reducing furnace 11 and heated to form molten Mg 1, then TiCl4 is blown into the vessel from a nozzle 13 and allowed to react with the molten Mg to reduce the TiCl4 to obtain Ti and MgCl2, and the mixtures 2 drawn off from the bottom of the vessel 12 through a valve 20 and introduced into a water-cooled copper crucible 23 with the upper and lower ends opened in a melting and separating device 21 filled with an Ar atmosphere. A Ti ingot is previously put in the crucible 23, and the mixture of Ti and MgCl2 is placed on the ingot and heated with the plasma from a plasma torch 22, etc. The MgCl2 is vaporized and discharged from an outlet 26, and the Ti is melted to form a Ti pool 3, then cooled by the crucible 23, solidified and discharged as a Ti ingot 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing titanium by reducing titanium tetrachloride, and more particularly to separating by-products (eg magnesium chloride) mixed with titanium obtained by the reduction reaction. The present invention relates to a titanium production method capable of continuously performing the steps from the step of producing to the step of producing an ingot.

[0002]

2. Description of the Related Art Titanium (Ti) is a typical metal produced by a reduction reaction of a metal halide. This titanium has been attracting attention as an industrially important metal since it has various excellent properties such as excellent corrosion resistance, high specific strength and high melting point.

As a method for producing titanium, a Kroll method in which purified titanium tetrachloride (TiCl ₄ ) is reduced with magnesium (Mg) which is an alkaline earth metal, and also TiCl ₄ is sodium which is an alkali metal. There is a Hunter method of reducing with (Na). Comparing these two methods, the Kroll method, which has been improved in the steps of reduction and separation, is excellent in terms of productivity and energy saving, and is widely applied as an industrial production method of titanium.

In the production of titanium metal by the Kroll method,
Using TiCl ₄ obtained by the chlorination treatment of titanium ore as an intermediate raw material, a sponge-like or needle-like sponge titanium is obtained by a reduction reaction, separation, and crushing-mixing treatment, which is then melted to produce an ingot. This ingot is processed into a predetermined shape and used for final use.

FIG. 5 is a diagram showing an outline of steps for producing titanium sponge by the Kroll method and producing a titanium ingot from the obtained titanium sponge.

In the reducing step (), it is necessary as a reducing agent.
Mg is charged into the reaction vessel 12 in the reduction furnace 11, the inside of the vessel is replaced with an inert gas (usually argon gas), and then heated and heated to melt the Mg. Reaction container containing this molten Mg
TiCl ₄ is dropped from a supply nozzle 13 to 12 and brought into contact with molten Mg in the reaction vessel to reduce it by the reaction of the following formula (A).

TiCl ₄ + 2 Mg → Ti + 2MgCl ₂ (A) At this time, if oxygen or the like is mixed in the reaction atmosphere, the titanium sponge will be contaminated. Must be done in-house. Therefore, the production of titanium including the Kroll method is a batch system in which the reaction vessel used in the reduction step is a production unit.

In the reaction of the above formula (A), titanium sponge is used.
A by-product MgCl ₂ is simultaneously formed with (Ti).
This MgCl ₂ is appropriately extracted to the outside of the reaction container 12, but finally remains in the titanium sponge together with unreacted Mg.

In the separation step (), a vacuum separation method or a leaching method is carried out in order to remove unreacted Mg and the above-mentioned by-product MgCl ₂ and to take out only metallic titanium. Many vacuum separation methods are used because of their low quality and stability.

In the vacuum separation method, the reaction container 12 containing titanium sponge in which Mg and MgCl ₂ remain is housed in a vacuum separation furnace 14, and the inside of the reaction container 12 is suctioned to a vacuum state. Further, heating is performed from the outside of the reaction container 12 to evaporate the residual component contained in the titanium sponge in the reaction container 12. The evaporated residue is discharged to the outside of the vacuum separation furnace 14 and condensed by the condenser 15, for example, and collected. The titanium sponge thus purified is extruded from the reaction vessel 12 as a cylindrical cake.

The above cylindrical cake has component segregation (concentration segregation of residues etc.) in the longitudinal direction and the radial direction.
Therefore, if a consumable electrode to be described later is manufactured from the state as it is, component segregation will occur in the product ingot. Therefore, the following pulverizing and mixing step is required.

In the crushing and mixing step (), the cylindrical titanium sponge is crushed by the cutting press 16 and then crushed into fine particles (usually 1/2 inch or less) by a jaw crusher (not shown). The titanium sponge thus crushed to a predetermined particle size is mixed with a blender or the like.

The crushed mixture of titanium sponge manufactured in the above steps is compression-molded into the shape of the consumable electrode 17 for use in the melting step. In the process of the consumable electrode
17 is, for example, arc melted in a vacuum of 10 ^-2 to 10 ^-3 Torr,
Titanium ingot 4 is manufactured.

[0014]

As described above, the conventional method for producing titanium is a batch type in which a reaction vessel is used as a production unit, and a reduction reaction, vacuum separation, and crushing are performed before an ingot of titanium metal is produced. Many manufacturing processes are required, which are independent of mixing, electrode forming and arc melting. Therefore, the conventional titanium manufacturing process requires a lot of manpower, and not only the production efficiency is low, but also titanium contamination is likely to occur during the handling between manufacturing processes and during the manufacturing process (for example, the pulverizing and mixing process described above). There is a point.

In view of the problems of the conventional titanium production technique, the present invention has a high productivity and a high productivity due to impurities by making the step of separating the reaction by-product from the step of producing the ingot continuous after the reduction reaction. The purpose of the present invention is to provide a method for producing titanium which is stable in quality and has no pollution.

[0016]

DISCLOSURE OF THE INVENTION The gist of the present invention is a method for producing titanium, which is characterized in that the following steps are sequentially carried out.

A step of reducing titanium tetrachloride with an alkali metal or an alkaline earth metal in a reaction vessel.

A step of withdrawing a mixture of the produced titanium and a halide of an alkali metal or an alkaline earth metal, which is a reaction by-product, from the reaction vessel.

A step of accommodating the extracted mixture in an upper and lower open type crucible and heating it therein to melt titanium in the mixture and evaporate the halide.

A step of solidifying titanium and pulling it out from the upper and lower open type crucible to form an ingot.

The heating in the above steps is preferably performed by plasma heating, high frequency induction heating or a combination of high frequency induction heating and plasma heating. In the case of plasma heating, it is desirable to use a water-cooled copper crucible as the upper and lower open type crucible, and in the case of heating by high frequency induction heating or a combination of high frequency induction heating and plasma heating, a split type water cooled copper crucible is preferably used.

[0022]

In the conventional titanium production method, the process cannot be made continuous because a common reaction vessel is used for the reduction reaction and the vacuum separation. Titanium sponge must be produced for each production batch regulated by this container, and thereafter, batch processing is required from the melting of titanium to the production of an ingot for quality control.

The feature of the method of the present invention is that a mixture of titanium produced in the reduction step of TiCl ₄ and MgCl _{2 which} is a by-product,
The purpose is to take out from the reaction vessel, separate MgCl ₂ and produce an ingot continuously by one apparatus.

FIG. 1 is a schematic cross-sectional view showing an example of an apparatus used in a later-described embodiment, in which plasma heating is adopted as a heat input means. Hereinafter, a specific method for producing titanium in the case of carrying out the method of the present invention based on the Kroll method will be described with reference to this drawing.

The production process adopted in the present invention is the reaction product (Ti) and by-product (Mg) of the reduction process as described above.
Cl ₂ ) withdrawing the mixture with from the reaction vessel, the melting and separating step, and the ingot manufacturing step,
At least the steps and steps are continuously performed. Less than,
Each step will be described.

Step (TiCl ₄ reduction step) In this reduction step, TiCl ₄ as an intermediate raw material is reduced with Mg to obtain a mixture of titanium metal and MgCl ₂ as a by-produced halide.

The reduction furnace 11 of FIG. 1 has a built-in heating device and heats the inside to a predetermined temperature. First,
As a reducing agent in the closed reaction vessel 12 installed in the reduction furnace 11.
Mg is added and the inside of the reduction furnace 11 is heated to obtain molten Mg1. After that, TiCl ₄ was supplied from the supply nozzle 13 provided on the upper part of the reaction vessel 12.
To supply.

With the supply of TiCl ₄ , TiCl ₄ is
As shown in the formula (A), it is reduced by Mg, and a mixture ₂ of titanium and MgCl 2 is produced inside the reaction vessel 12. Since this mixture 2 has a larger specific gravity than molten Mg, it gradually settles and collects at the bottom of the reaction vessel 12.

Normally, the molten Mg1 which is sharply separated by the difference in specific gravity is not mixed in the mixture 2, but even if a small amount of unreacted Mg is mixed in the mixture 2, the Mg component is also contained in the dissolution / separation step described later. Since it is separated, there is no problem.

Step (reaction product withdrawing step) The mixture 2 is withdrawn in a fixed amount by operating the withdrawing valve 20 from a pipe provided at the bottom of the reaction vessel 12 in a molten state. This mixture is then mixed with MgCl ₂ in the conventional method.
Is supplied to the next dissolution / separation step without performing the vacuum separation, that is, with the titanium and MgCl ₂ mixed as they are. Note that, as the reduction reaction progresses, the reducing agent Mg is replenished to the reaction vessel 12 from above the reaction vessel 12.

Step (dissolution / separation step) The dissolution / separation apparatus 21 shown on the right side of FIG. 1 is used. Inside this apparatus, a vertically open crucible (water-cooled copper crucible in the example of FIG. 1) 23 is installed, and a plasma torch 22, for example, is provided as heat input means above it. Crucible
Since 23 also serves as a mold for producing an ingot, it must be a tubular one whose upper and lower sides are open.
The inside of the dissolution / separation device is made an inert atmosphere with, for example, argon gas.

To start the operation, first, a titanium ingot for initial melting is inserted into the crucible 23, and the upper surface of the ingot is heated and melted by the plasma torch 22 to form the pool 3 of molten titanium. When the pool of molten titanium becomes stable, the mixture extracted in the previous step is supplied to the pool 3 in a fixed amount in a molten state. The supply to the pool 3 may be performed by once cooling and solidifying the extracted mixture and then pulverizing it.

The supplied mixture is heated by the heat input means. Since the boiling point of MgCl ₂ (about 1412 ° C) is lower than the melting point of titanium (1660 ° C), keeping titanium in the molten state causes MgCl ₂ in the mixture to immediately rise above the boiling point and evaporate. It is discharged outside, condensed, liquefied and collected.

Molten titanium constitutes a new molten titanium pool 3 and is cooled in the next step to be an ingot.

Step (Ingot Production Step) The molten titanium from which MgCl ₂ has been sufficiently evaporated and separated is sequentially cooled from the bottom of the pool 3 and solidified to form an ingot 4. This ingot is drawn downward at a constant speed, and the mixture 2 into the pool 3 is adjusted according to the drawing speed.
If the supply amount of is adjusted, the dissolution / separation step and the ingot manufacturing step can be performed simultaneously and continuously.

The ingot can be pulled out by a known means such as a pinch roll (not shown).

The crucible (which also serves as a mold) used in the above steps (1) and (2) is made of metal having a cooling water passage inside, but a water-cooled copper crucible is particularly preferable. This is because the thermal conductivity of copper is large, so that the surface of the crucible in contact with the molten titanium is sufficiently cooled and the reaction with titanium does not occur.

It is also possible to keep the mixture in a molten state and
The heat input means used to evaporate MgCl ₂ is preferably plasma heating or high frequency induction heating or a combination thereof. This is because all of them can locally input heat and the exothermic part does not react with titanium or MgCl ₂ in the mixture.

Further, when the heat input means is high frequency induction heating or a combination of high frequency induction heating and plasma heating, the crucible is preferably a split type water cooled copper crucible. A water-cooled copper crucible, which was divided so as to be electrically insulated from each other, was placed in the high-frequency induction coil, and when a magnetic field was transmitted through the copper crucible, the molten titanium was brought into contact with the crucible by magnetic pressure. It will be retained and dissolved. Since there is no contact between the inner wall of the crucible and the molten titanium, contamination of the titanium by the metal forming the crucible is avoided, damage to the crucible is reduced, and its life is extended.

FIG. 4 is a schematic diagram showing an example of this split type water-cooled copper crucible. In the figure, the upper part of the crucible 24 is divided into segments 28 by a slit 27, and the above effect is exhibited by exciting the high frequency induction coil 25.

The steps from to can be carried out continuously. That is, Mg and TiCl ₄ were continuously supplied into the reaction vessel 12, and the produced mixture 2 was continuously withdrawn,
By continuously supplying this to the dissolution and separation apparatus and further extracting the ingot according to the supply amount, all the steps can be made continuous. Of course, it is also possible to perform an operation in which the step and the step are separated and the mixture extracted in the step is once cooled and then sent to the step.

Although the method for producing titanium according to the present invention has been described above based on the Kroll method, it can be operated in the same manner by the Hunter method.

[0043]

EXAMPLES The method for producing titanium according to the present invention will be described in detail with reference to Examples 1 to 3 in which the heat input means is changed.

Example 1 The apparatus shown in FIG. 1 was used. As described above, this apparatus uses plasma heating as a heat input means in the mixture melting / separating step and a water-cooled copper crucible as a crucible. The operating conditions in each process from the reduction process to the ingot production are as follows.

Reduction Step As the reaction vessel 12 in FIG. 1, a steel closed vessel having a diameter of 1.2 m and a height of 3 m was used. First, 2.4 tons of MgCl ₂ was charged into the reaction vessel 12, and then 1.2 tons of MgCl ₂ was used as a reducing agent.
Then, the inside of the reduction furnace 11 was heated to 800 ° C. afterwards,
TiCl ₄ was supplied at a flow rate of 120 kg / Hr from a supply nozzle 13 provided at the upper part of the reaction container 12.

As TiCl ₄ is supplied, TiCl ₄ melts
It is reduced by Mg and inside the reaction vessel 12 titanium and Mg
A mixture ₂ of Cl ₂ was produced and settled at the bottom of the reaction vessel 12 due to the difference in specific gravity. The composition of this mixture was: MgCl ₂ : 75% by weight, Ti: 25% by weight.

Extraction Step of Mixture The mixture 2 accumulated in the lower part of the reaction container was operated at an extraction valve 20 and extracted at a rate of 150 kg / min. This extraction was started after waiting for the molten titanium pool in the next step to stabilize.

Liquid Mg was supplied from the upper part of the reaction vessel 12 at any time in order to supplement Mg of the reducing agent that was consumed as the reduction reaction proceeded. In addition, MgCl ₂ which does not contain titanium is
Extraction can also be performed by overflow or the like without passing through the extraction valve 20.

Melting / Separation Step The inside of the melting / separating apparatus 21 is made an inert atmosphere with argon gas, and a water-cooled copper crucible 23 having an inner diameter of 200 mm is provided inside thereof.
And a titanium ingot 4 for initial melting was inserted.
Above the water-cooled copper crucible 23, a non-transfer type plasma torch 22 is provided as a heat input means, and the plasma torch heats and melts the upper surface of the titanium ingot in the water-cooled copper crucible 23 to form the pool 3 of molten titanium. Formed.

When the molten state of the molten titanium pool 3 on the upper surface of the titanium ingot 4 is stabilized, titanium and MgCl 2 extracted from the bottom of the reaction vessel 12 in the step of
The mixture 2 of _2, was fed at a constant amount (150 kg / min) increments molten titanium 3. During this time, heating by the plasma torch 22 was continued, and MgCl ₂ in the supplied mixture ₂ was evaporated and separated.

Manufacturing process of ingot Speed corresponding to the feeding speed of the above mixture (265 mm / min)
Then, the ingot 4 was pulled out downward. When the ingot thus produced was analyzed, Ti: 99.99% by weight, and it was confirmed that titanium was sufficiently purified in the melting / separating step.

(Embodiment 2) FIG. 2 is a schematic sectional view of an apparatus used in this embodiment. Here, high-frequency induction heating by the high-frequency coil 25 is adopted as the heat input means. As the crucible, a split type water-cooled copper crucible 24 having a schematic configuration shown in FIG. 4 was used. The steps and conditions were the same as in Example 1. The process of was operated under the following conditions.

Melting / Separation Step As shown in FIG. 2, inside the melting / separating apparatus 21, a split-type water-cooled copper crucible 24 divided into 16 segments with an inner diameter of 95 mm was installed inside a high-frequency coil 25. The titanium ingot for initial melting is held in a split water-cooled copper crucible 24,
The high-frequency coil 25 was induction-heated with the energization, and the upper part thereof became a molten state to become the molten titanium pool 3. At this time, the molten titanium pool 3 was pushed toward the center of the crucible by the action of the magnetic field induced by the high frequency current, and was separated from the inner wall of the crucible.

Then, the mixture 2 was supplied to the molten titanium pool 3 in a constant amount, while the molten titanium from which MgCl ₂ had been separated was continuously solidified and withdrawn to produce the titanium ingot 4. Same as the case.

In this Example 2, since there was no contact between the inner wall of the water-cooled copper crucible and the molten titanium, it was possible to manufacture an ingot with less contamination than Ti: 99.99% by weight.

(Embodiment 3) The apparatus shown in FIG. 3 in which plasma heating and high frequency induction heating were combined was used.

Also in this case, the crucible is a split type water-cooled copper crucible.
24 was used. The steps and were set to the same conditions as in Example 1, and the step was operated under the following conditions.

Dissolution / Separation Step The internal configuration of the dissolution / separation device 21 is as shown in FIG.
Inside the high-frequency coil 25, while installing a split type water-cooled copper crucible 24 divided into 16 segments with an inner diameter of 95 mm,
A non-transferred plasma torch 22 was installed above the crucible so that the plasma flame reached the upper surface of the titanium ingot 4. By a high frequency induction heating, the upper part of the titanium ingot for initial melting was used as a molten titanium pool 3, and a fixed amount of the mixture 2 extracted in the reduction step was supplied.

In this example, in order to promote the evaporation and separation of MgCl _{2 in} the mixture, plasma heating from above was also used in combination to dissolve titanium and produce an ingot. The combined use of plasma heating improved the power efficiency as compared with Examples 1 and 2, and was able to improve the production rate of titanium. Here, the power efficiency is represented by the amount of input power per unit weight of the generated titanium ingot.

The titanium ingot thus obtained had little contamination, like the ingot obtained in Example 2.

[0061]

According to the method for producing titanium of the present invention, TiCl
After the reduction reaction of ₄ , it is possible to continuously perform from the evaporation separation of MgCl ₂ which is a by-product in titanium to the production of a titanium ingot, and it is possible to significantly improve the productivity in the production process, It is possible to produce titanium which is stable in quality without contamination by impurities.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus used in the method of the present invention, in which plasma heating is adopted as a heat input means.

FIG. 2 is a schematic cross-sectional view showing another example of the apparatus used in the method of the present invention, in which high-frequency induction heating is adopted as the heat input means.

FIG. 3 is a schematic cross-sectional view showing another example of the apparatus used in the method of the present invention, which employs a combination of plasma heating and high frequency induction heating.

FIG. 4 is a schematic configuration diagram showing an example of a split-type water-cooled copper crucible.

FIG. 5 is a diagram showing an outline of a main production process of conventional sponge titanium and a production process of a titanium ingot using titanium sponge as a raw material by the Kroll method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Molten Mg, 2 ... Mixture, 3 ... Molten titanium pool 4 ... Titanium ingot, 11 ... Reduction furnace, 12 ... Reaction vessel, 13
… TiCl ₄ supply nozzle 14… Vacuum separation furnace, 15… Condenser, 16… Cutting press, 17…
Consumable electrode 20 ... Extraction valve, 21 ... Melt / separator, 22 ... Plasma torch 23 ... Water-cooled copper crucible, 24 ... Split-type water-cooled copper crucible, 25 ...
High frequency coil 26… MgCl ₂ outlet, 27… slit, 28… segment, 29… cooling water

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshitake Natsume, 1 Higashihama-cho, Amagasaki-shi, Hyogo Sumitomo Sitix Co., Ltd. (72) Kenji Fujita, 1st, Higashi-hama-City, Amagasaki-shi, Hyogo (72) Invention Hisayuki Wada, 1st Higashihama-cho, Amagasaki-shi, Hyogo Sumitomo Sitix Co., Ltd. (72) Inventor Kazuki Tabata 1st, Higashi-hama-cho, Amagasaki-shi, Hyogo Sumitomo Sitix Co., Ltd.

Claims (3)

[Claims] 1. A method for producing titanium, which comprises sequentially performing the following steps. A step of reducing titanium tetrachloride with an alkali metal or an alkaline earth metal in a reaction vessel. A step of extracting a mixture of the produced titanium and a halide of an alkali metal or an alkaline earth metal, which is a reaction by-product, from the reaction vessel. A step of accommodating the extracted mixture in an upper and lower open type crucible and heating in the crucible to melt titanium in the mixture and evaporate the halide. The process of solidifying titanium and pulling it out from the upper and lower open crucible to make an ingot. 2. The method for producing titanium according to claim 1, wherein the upper and lower open type crucible used in the step of claim 1 is a water-cooled copper crucible, and the mixture is heated by plasma heating. 3. The upper and lower open type crucible used in the step of claim 1 is a split type water cooled copper crucible, and the mixture is heated by high frequency induction heating or a combination of high frequency induction heating and plasma heating. 1. The method for producing titanium according to 1.