JPH062917B2 - Method for producing metallic titanium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for obtaining metal Ti from titanium fluoride as a raw material.

[Prior Art] As a method for producing metallic Ti, the Kroll method described in "Nonferrous metal milling" (Japan Institute of Metals, Sho 39, p272-p274) is known. Titanium (T
Chlorination of iO ₂ ) and reduction of titanium tetrachloride (TiCl ₄ ) with metallic magnesium (Mg). However, in order to decompose and produce Mg from the produced magnesium chloride (MgCl ₂ ), a large amount of electric power of about 20000 kwh per 1000 kg of titanium is required, and the use of expensive titania (TiO ₂ ) is a big economic problem. Has become a problem. Therefore, a method has been proposed in which TiF ₄ is used as a reducing agent, which is inexpensive metal aluminum.

For example, in JP-A-60-17026, a fluorine-containing compound of titanium is used in a reducing gas atmosphere or in a vacuum.
A method for producing metallic titanium by contacting with aluminum or magnesium heated to 0 ° C. or higher is disclosed. The basic reaction is the following reaction.

TiF ₄ + (4/3) Al → Ti + (4/3) AlF ₃ (1) Formula Further, in US Pat. No. 4,468,248, Na ₂ TiF ₆ is made from ilmenite (TiO ₂ —FeO), and The production of Ti by reaction is described.

Na ₂ TiF ₆ + (4/3) Al → Ti + (2/3) Na ₃ AlF ₆ · AlF ₃ (2) Formula [Problems and actions to be solved by the invention] Japanese Patent Laid-Open No. 60-17026 In the method by No. 22
It is unclear whether TiF ₄ and Al react sufficiently at 0 ° C. or higher, and Ti and AlF ₃ are further separated. Also, the manufacturing process is not specifically described. US Patent 4468
In the method of No. 248, as shown in the reaction (2), a large amount of pseudo cryolite (Na ₃ AlF ₆ · AlF ₃ ) is generated, and this must be economically diverted. In addition, dumping pseudo cryolite causes outflow of F ions, which is also a problem in terms of pollution. Therefore, there is a problem that expensive F must be reused.

Assignments solutions to means and operations for] the problem is to heat the solid titanium fluoride (TiF _4), the step of vaporizing the gaseous titanium fluoride (TiF _4), said gaseous fluoride Titanium (TiF ₄ ) is supplied to a molten bath composed of a Zn bath containing Al and a solvent of an alkali metal salt on the Zn bath, and TiF ₄ is reduced by Al in the Zn bath to form Ti. While suspended in the solution, aluminum fluoride (Al
F ₃ ) absorbed in a solvent to liquefy, reduced Ti
In which the Zn bath in which is suspended is separated from the solvent, Zn is evaporated and removed from the separated Zn bath under reduced pressure to obtain metallic titanium, and the solvent in which aluminum fluoride (AlF ₃ ) is absorbed is reduced in pressure. Heat under aluminum fluoride (A
1F ₃ ) is vaporized and recovered to solve the problem.

In the present invention, TiF ₄ vaporization process, TiF ₄ reduction, Al
The F ₃ liquefaction process, the Zn bath and the dissolved salt separation process, and the Zn evaporation removal process are sequentially arranged to convert solid titanium fluoride into gaseous titanium fluoride, which is reduced by Al on the Zn bath. Then, Ti is suspended in the Zn bath to separate it from the solvent that has absorbed the by-product aluminum fluoride (AlF ₃ ), and then Zn is evaporated and removed under reduced pressure to obtain metallic titanium.

Furthermore, the liquid Zn can be recovered by providing a liquid Zn recovery process after the Zn evaporation removal process. Furthermore, A
The AlF _{3 H} 2 O after the step of recovering evaporated lF ₃
Alumina (Al ₂ O ₃ ) and hydrofluoric acid (HF)
It is possible to provide a step of decomposing into.

Further, as the solvent of the alkali metal salt, an alkali metal fluoride, chloride, or a mixture of fluoride and chloride can be used.

[Examples of the Invention] The manufacturing method of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a flow chart showing the manufacturing process of the method of the present invention. FIG. 2 is a diagram showing a manufacturing apparatus for carrying out the method of the present invention.

TiF ₄ vaporization step The TiF ₄ vaporization step 14 is a vaporizer 15 equipped with a heating device.
Done by The vaporizer 15 is maintained at at least 250 ° C. or higher. The TiF ₄ 12 charged into the vaporizer 15 as a raw material is heated to generate gaseous TiF ₄ 16. Since the sublimation point of TiF ₄ is about 298 ° C., it is preferably 250 ° C. or higher to obtain a sufficient gas generation rate. It is heated up to a maximum of 900 ℃ in order to improve the operation rate. The produced gaseous TiF ₄ 16 may be used alone or by using argon gas as a carrier gas through a pipe or the like as described below.
It is sent to the reactor 19 where the iF ₄ reduction / AlF ₃ liquefaction process 18 is performed.

Reduction process of TiF ₄ and liquefaction process of AlF ₃ The reactor 19 is previously heated by an attached heating device.
Zn heated to 600-1000 ℃ and containing up to 50% Al
Alkali metal fluorides, chlorides or mixtures thereof are mainly added to the bath and the Zn bath. TiF ₄ 16 blown into the bath reacts with Al in the Zn bath to form metallic Ti.
To generate. This reaction is represented by formula (1).

TiF ₄ + (4/3) Al → Ti + (4/3) AlF ₃ (1) Equation (1) has a lower free energy of reaction at lower temperatures (negative value is an absolute value. Large), 1000 ° C or higher is not desirable. Further, it is preferably 400 ° C. or higher because it is not desirable at a very low temperature from the viewpoint of reaction rate. AlF ₃
Sublimates at 1291 ° C and is a solid up to this temperature. Therefore, in order to liquefy AlF ₃ , mainly alkali metal fluoride, chloride or a mixture thereof is added as a solvent onto the Zn bath. AlF ₃ generated by the reaction of the formula (1) is dissolved and absorbed in a solvent to become a liquid. When the reaction of the formula (1) is completed, if a solvent is added so that AlF ₃ becomes 50 mol% or less, the fluoride containing AlF ₃ becomes a liquid at 800 ° C. or more.

The reason for liquefying AlF ₃ is to facilitate separation from the molten Zn bath. TiF ₄ 16 is preferably blown into a Zn bath containing up to 50% Al in order to increase the reaction rate. The metallic Ti thus produced is suspended in the Zn bath in the form of particles or powder. At this time, it is necessary to adjust the reaction amount so that Ti is present in the Zn bath in a maximum amount of 30 Mol% (76% by weight).
This is because when the temperature inside the reactor 19 is 1000 ° C. or lower, the content of Ti is 30 mol% and the Zn bath changes into a solid. When the reaction of the formula (1) is completed, Al in the Zn bath is preferably 1% or less. Separation step 4 for separating Zn bath and molten salt
Processing in 7 is performed.

Step of separating Zn bath and molten salt Here, using the reactor 19, the Zn 22 in which Ti suspended in the lower layer from the bottom of the reactor 19 is taken out and separated.
It is sent to the n evaporation removal process 26. AlF ₃ solvent 24 that has absorbed AlF ₃ remaining in the reactor 19 to be described later
Is processed in the evaporation and recovery process of.

Zn Evaporation and Removal Step The Zn evaporation and removal step 26 is performed by the distiller 27.
Liquid Z in which Ti is suspended when the reaction of the formula (1) is completed
n22 flows into the still 27. Zn has a melting point of 419 ° C
Therefore, it is necessary to maintain the temperature above 419 ° C.
In this state, if the pressure is appropriately reduced and Zn is removed as gaseous Zn 28, powdery metal Ti 34 is obtained.

Zn recovery step The Zn recovery step 30 is performed by the capacitor 31. The gaseous Zn 28 from the still 27 is cooled to a temperature of 419 ° C. or higher and 900 ° C. or lower, and the liquid Zn 32 is recovered. This Zn3
2 again flows into the reactor 19 and is reused in the reduction reaction shown in (1).

AlF ₃ evaporation / recovery step After the reduction of TiF ₄ and the liquefaction of AlF ₃ are completed, the solvent 24 absorbing AlF ₃ remains in the reactor 19 even if the Zn bath in which Ti is suspended is separated. There is. This reactor 19 to 60
When the temperature is raised from 0 to 1000 ° C. to 1000 to 1200 ° C. and the pressure is appropriately reduced, AlF ₃ is gasified and gaseous AlF ₃ 38 is generated. Since AlF ₃ has a vapor pressure of about 230 Torr at 1200 ° C., it vaporizes at a sufficient rate under a pressure of 10 to 760 Torr. On the other hand, since the vapor pressure of the solvent is low, it does not substantially evaporate and remains in the reactor 19.

AlF ₃ separation step AlF ₃ vaporization and recovery step 36: gaseous Al vaporized
F ₃ 38 is introduced into the decomposer 41 through a pipe. In the decomposer 41, the water vapor 42 is added, and hydrogen fluoride (HF) 44 and alumina (Al ₂ O ₃ ) 46 are generated by the reaction of the following formula (3).

AlF ₃ + (3/2) H ₂ O → Al ₂ O ₃ + HF (3) Formula Thermodynamically, this reaction should be carried out at a temperature of 800 ° C to 1200 ° C. Alumina generated here (Al ₂
O ₃ ) 46 can be used as a raw material for alumina bricks, for example. Further, it is economical to reuse the generated hydrogen fluoride (HF) 44 as a raw material when producing TiF ₄ from ilmenite ore.

The manufacturing method of the present invention has been described above with reference to FIGS. 1 and 2. In FIG. 2, the vaporizer 15, the reactor 19, the distiller 27, the condenser 31, and the decomposer 41 are each provided in a single unit. It is more preferable to manufacture it. Further, as the vaporizer 15, the distiller 27, the condenser 31, and the decomposer 41, the conventionally known devices may be used, but the reactor 19 needs to be devised because it is a gas-liquid reaction. That is, it is desirable to directly blow gaseous TiF ₄ 16 into the Zn bath through a plurality of pipes in order to increase the reaction rate.

Solvent is added in the liquefaction step of reducing · AlF ₃ of TiF ₄ has a function of absorbing the AlF _3, there in liquid form at the reaction temperature of 600 to 1000 ° C., and compared it is sufficiently low vapor pressure to AlF ₃ Is desirable. This is because AlF ₃ must be extracted as vapor. As the solvent, LiF, NaCl, NaF, CaF ₂ , KF, Mg
There are F etc. Any of these solvents can be used, but LiF is most preferable because it has a large ability to dissolve and absorb solid AlF ₃ particularly in terms of vapor pressure and in a molten state.
As a matter of course, the above solvent may be appropriately mixed.

By the way, the vapor pressure at 1100 ° C is 42.7 Torr for AlF ₃ .
2.19 Torr for LiF, 1.55 Torr for NaF, 1.0 for CaF _2.
× 10 ^-4 Torr, KF is 15.62 Torr.

Although the manufacturing method of the present invention has been described above with reference to FIGS. 1 and 2, the manufacturing process based on FIG. 1 may be performed according to the flow of the manufacturing apparatus shown in FIG. That is, after the completion of the reduction process 18 of TiF ₄ and the liquefaction process 18 of AlF ₃ , the liquid Zn 22 containing Ti is introduced into the still 27, while the solvent 24 containing AlF ₃ is introduced into the evaporator 37 to separate them. Thereafter, the liquid Zn 22 containing Ti is subjected to a Zn evaporation removal step 26 and a Zn recovery step 30. Also,
For solvent 24 containing AlF _3, evaporation of AlF ₃ ·
The recovery step 36 and the AlF ₃ decomposition step 40 are performed. This method is different in that the solvent after the reaction is not left in the reactor. Therefore, the advantage of this method is that the Ti
Since the total amount of the Zn bath containing Al and the solvent 24 containing AlF ₃ is discharged, the Zn reduction can be immediately utilized for the same reduction reaction, so that the above steps can be continuously operated.

Although there are various methods for producing solid TiF ₄ 12 as a raw material, it is preferable to produce it by the following production method. For example, as disclosed in Japanese Patent Application No. 62-306921 by the same applicant, (1) a titanium raw material containing iron is dissolved in a solution containing hydrofluoric acid to form a fluorinated solution.

(2) The ferric fluoride crystal is crystallized and separated by cooling the fluorinated solution to produce a crude titanium fluoride solution.

(3) An ammonium fluoride solution is mixed with the crude titanium fluoride solution, and the mixture is evaporated and concentrated to crystallize and separate the ammonium fluoride salt, and a fluorine-containing salt and a fluoride-containing solution containing ammonium fluoride are dissolved. An ammonium chloride solution is produced.

(4) The ammonium fluoride salt is dried and then thermally decomposed in a dry gas stream at 300 to 800 ° C. to produce ferric fluoride as a solid and TiF ₄ , HF, NH ₃ as a gas.

(5) The gas is condensed at 20 to 280 ° C. to obtain TiF ₄ and HF.
-Condensation and separation into NH ₃ gas.

(6) Ammonium fluoride solution is prepared by adding HF / NH to ammonium fluoride solution containing dissolved ammonium fluoride salt.
It is made by absorbing ₃ gases.

In the above method, the by-product Al in the method of the present invention is used.
Hydrogen fluoride (HF) generated when F ₃ is finally converted into Al ₂ O ₃ can be used for the regeneration of the ammonium fluoride solution, which has a large economic merit.

Next, examples of the present invention will be specifically described in detail.

(Example) The reactor 19 was previously made of Zn: 18 kg, Al: 4.4 kg of 900
A Zn bath at ℃ was prepared, and LiF (17 kg) as a solvent was added and placed. TiF ₄ was vaporized in the vaporizer 15 at a temperature of 600 ° C., and TiF ₄ : 10 kg was introduced into the reactor 19 in 1 hour. Thirty minutes after the introduction of TiF ₄ , the Zn bath was fed into the still 27, and the temperature inside the still 27 was maintained at 600 ° C. The gaseous Zn generated in the still 27 was cooled by the condenser 31, and the liquid Zn 32 was recovered. 3.5 kg of Ti powder remained in the still 27. The yield of Ti is 90%. 17.5 kg of Zn was recovered from the condenser 31. Zn yield is 97
%Met. On the other hand, the reactor 19 is heated to ₁ 1100 ° C. After the reaction, was generated _AlF 3 38. The AlF ₃ 38 is guided to a decomposer 41, where steam 42 is added and decomposed into hydrogen fluoride (HF) 44 and alumina (Al ₂ O ₃ ) 46. Recovered HF is 6.1kg (recovery rate is 95%),
Further, the obtained Al ₂ O ₃ was 15 kg (yield 91%). Although the yield is slightly low, this is due to the raw materials and the like attached to the inner wall of each container. Therefore,
The recovery rate can be improved by continuous operation. Although it is a small pilot plant, it has been proven to be economical enough.

As described above, according to the present invention, the TiF ₄ vaporization step,
Since metallic titanium is produced through the steps of reducing TiF ₄ , liquefying AlF ₃ , and evaporating and removing Zn, it is possible to produce inexpensive powdery metallic titanium. That is, the titanium metal powder can be obtained at about 30% cheaper than the conventional Kroll method. In the crawl method, a lump having a diameter of 2 m and a length of 4 m can be obtained, depending on the size of the apparatus. A lot of energy is required to crush this lump with a crusher, and only a non-uniform lump is obtained. According to the present invention, powdery metallic titanium having a diameter of 1 mm or less can be directly obtained, which is convenient. Furthermore, according to the present invention, since the AlF ₃ evaporation / recovery step and the AlF ₃ decomposition step are provided, it is advantageous from the viewpoint of resource reuse and pollution. That is, Al used as the reducing agent is Al ₂ O ₃
Can be used as a raw material for refractories. Expensive HF can be recovered and reused for the production of TiF ₄ , which is a great advantage in terms of pollution. When compared with the production method of US Pat. No. 4,468,248, a large amount of Na is generated by this method.
_It is not necessary to process ₃ AIF ₆ .AlF ₃ . This substance contains F and cannot be discarded due to pollution.

[Brief description of drawings]

FIG. 1 is a flow chart showing the manufacturing steps of the method of the present invention, FIG. 2 is a drawing showing a manufacturing apparatus for carrying out the method of the present invention, and FIG.
The figure shows another manufacturing apparatus for carrying out the method of the present invention. 12 ... Solid TiF ₄ , 14 ... TiF ₄ vaporization step, 1
5 ... Vaporizer, 16 ... Gaseous TiF ₄ , 18 ... TiF ₄
Reduction step, AlF ₃ liquefaction step, 19 ... Reactor, 20 ... Al, 22 ... Ti suspended liquid Zn, 24 ... SolF absorbing AlF ₃ ; 26 ... Zn evaporation removal step, 27 ... Distiller, 28 ... Gaseous Zn, 30 ... Zn recovery process, 31 ... Capacitor, 32 ... Liquid Zn, 34 ... Powder metal Ti, 36 ... AlF ₃ evaporation / recovery process, 37 ... Evaporator, 38 ... Gaseous AlF ₃ , 40 ... A
decomposition step of lF _3, 41 ... decomposer, 42 ... _{steam, 44 ... HF, 46 ... Al} 2 O 3.

Claims (4)

[Claims] 1. A heating a solid titanium fluoride (TiF _4), Zn bath comprising the step of vaporizing the gaseous titanium fluoride (TiF _4), said gaseous fluorinated titanium (TiF ₄₎ Al And a solvent of an alkali metal salt on the Zn bath to supply TiF ₄ with Al in the Zn bath to reduce Ti to Ti, resulting in reduction while suspended in the Zn bath. By-product aluminum fluoride (Al
F ₃ ) absorbed in a solvent to liquefy, reduced Ti
In which the Zn bath in which is suspended is separated from the solvent, Zn is evaporated and removed from the separated Zn bath under reduced pressure to obtain metallic titanium, and the solvent in which aluminum fluoride (AlF ₃ ) is absorbed is reduced in pressure. Heat under aluminum fluoride (A
and a step of evaporating and recovering 1F ₃ ), and a method for producing metallic titanium. 2. The method for producing metallic titanium according to claim 1, wherein the solvent of the alkali metal salt is an alkali metal fluoride, chloride, or a mixture of fluoride and chloride. 3. The liquid Zn containing the liquid Zn after the step of evaporating and removing Zn from the Zn bath separated from the solvent in the method according to claim 1 or 2 under a reduced pressure to obtain metallic titanium. A method for producing titanium metal, comprising the step of recovering titanium. 4. The method of claim 1, fluoride obtained in the step of recovering aluminum fluoride after the step of recovering evaporated aluminum fluoride in claim 2 or claim 3 method according (AlF ₃₎ (AlF ₃₎ A method for producing metallic titanium, comprising the step of reacting aluminum fluoride (AlF ₃ ) with H ₂ O to decompose it into alumina (Al ₂ O ₃ ) and hydrofluoric acid (HF).