JPH01252531A - Production of titanium fluoride - Google Patents

Abstract

PURPOSE:To improve the yield of TiF4 and reduce the cost for the separation of iron, by separating FeF3 from a solution produced by the reaction of an iron-containing Ti raw material with a solution containing hydrofluoric acid and mixing the resultant crude solution of TiF4 with an NH4F solution. CONSTITUTION:An iron-containing Ti raw material 1 such as ilmenite is added with hydrofluoric acid 3 and subjected to fluorination and dissolution treatment 2 at >=40 deg.C. The obtained fluorinated solution 4 is cooled below the fluorination and dissolution temperature to effect the crystallization and separation 8 of ferric fluoric crystal 10 and obtain a crude TiF4 solution 9. The iron separation process can be carried out at a low cost since no organic solvent is used in the process. The obtained crude TiF4 solution 9 is mixed with an NH4F solution 26 prepared in the later step and concentrated by evaporation, cooling or their combination to effect the crystallization and separation 15 of ammonium fluoride salt of (NH4)2TiF6 and (NH4)3FeF6. The salt is dried and thermally decomposed in a dry gas stream at 300-800 deg.C into solid FeF3 and gaseous TiF4, HF and NH3. The gas is condensed at 20-280 deg.C to effect the condensation and separation of TiF4 23. The gas 24 containing HF and NH3 is absorbed in an NH4F solution 17 and utilized as an NH4F solution 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing highly pure titanium fluoride using iron-containing titanite ore as a raw material.

[Prior Art] Various methods have been reported for producing titanium fluoride (TiF4) from iron-containing titanium raw materials such as ilmenite ore (hereinafter referred to as ilmenite). For example, British Patent Application No. 29944/72 discloses the following.

(1) Mix oxidized ilmenite and ferric fluoride (FeF3) until all the iron in ilmenite becomes trivalent, and react by heating this mixture to form titanium fluoride (TiF) vapor. Ferric oxide (Fe2es)
to generate.

(2) Condensing the TiF4 vapor and recovering it as TiF4.

(3) Reacting a portion of ferric oxide (Fe2es) with acidic ammonium fluoride (NH4HF2) to produce ferric ammonium fluoride ((NH4)S Fe F6).

(4) Ferric ammonium fluoride <(NH4)3 Fe F6) is thermally decomposed to produce FeF
3 and NH4F and provide for reuse.

In addition, a method for producing metal Ti from ilmenite via titanium fluoride (TiF4) is described in ``Chemistry and Industry J 57.
(10), 387-392 (1983). This method states the following:

(1) Extracting Ti ions into an organic solvent from a T1 ion-containing aqueous solution obtained by dissolving ilmenite with an acid.

(2) Add NH4HF2 to the organic solvent from which Ti ions were extracted.
Bringing the containing liquid into contact and back-extracting Ti ions to obtain ammonium titanium fluoride ((NH4)2TiP6).

(3) Titanium ammonium fluoride ((NH4h TiF6) crystals are thermally decomposed in an inert gas atmosphere to produce titanium fluoride (TiF4).
This vapor is condensed to produce titanium fluoride (Ti).
To obtain Fa).

[Problems to be Solved by the Invention] The method of British Patent Application No. 29944/72 has the following problems.

(1) Since titanium fluoride is produced by a solid or solid-gas reaction between ilmenite ore and ferric fluoride, the yield of titanium fluoride is as low as about 91%.

(2) 150-250μm ilmenite ore and 1μm
It is said that it is desirable to fluoride the following ferric fluoride in a fluidized bed furnace, but since the particle sizes of these powders differ greatly, A decrease in iron reaction efficiency and contamination of ferric fluoride with recovered titanium fluoride are unavoidable, and some countermeasures are required, which poses a technical problem.

(3) 500-1 for oxidation treatment as pre-treatment of ilmenite ore, crushing of ferric fluoride and fluorination treatment
A fluidized bed furnace that can withstand a temperature of 500° C. is required, resulting in high manufacturing and equipment costs, which poses economical problems.

Next, in the hot medium extraction method, there is a problem that the technology regarding acid dissolution of ilmenite ore and treatment of iron-containing residual liquid after solvent extraction is unknown, and the running cost of the organic solvent is high.

This invention was made to solve problems such as steam, and aims to provide a method for producing titanium fluoride that can produce titanium fluoride in high yield and is more economically advantageous than conventional methods. purpose.

[Means for Solving the Problems] The present invention dissolves a titanium raw material containing iron in a solution containing hydrofluoric acid to produce a fluoride solution, and cools the fluoride solution to produce secondary fluoride. Ammonium fluoride salt [( NH4)2 T t F6 and (NH4
) mixed salt of sFeF6] is crystallized and separated, and the ammonium fluoride salt is thermally decomposed at 300 to 800°C in a dry gas stream to produce ferric fluoride (F e F 3) as a solid and TiF4 as a gas. Generate HF, NH, and convert the gas into 2
This is a method for producing titanium fluoride, in which titanium fluoride is condensed at 0 to 280°C and separated into TiF4 and HF-NHs gas.

[Effect]

The process flow of this invention will be explained based on FIG.

(1) Hydrofluoric acid (HFsol) 3 with a reaction equivalence ratio of 1.1 or more is added to iron-containing titanium raw material 1 such as ilmenite ore (hereinafter referred to as ilmenite), and fluoride dissolution 2 is carried out at 40°C or higher. Figure 2 shows the influence of reaction time and reaction temperature on the fluorination rate when 1.2 times the reaction equivalent of hydrofluoric acid is added.As can be seen from Figure 2, the reaction temperature in dissolving fluoride The higher the fluoridation rate, the shorter the fluoridation completion time, 60 ~
In the temperature range of 90° C., fluoride dissolution is almost completed within one hour. Although it is not necessary to crush ilmenite during fluoride dissolution, it may be crushed in order to shorten the dissolution time.

(2) Cool the fluoride solution 4 to below the fluoride dissolution temperature in the form of crystallization separation of ferric fluoride crystals,
Ferric fluoride crystal (F e F s・4.5 HaO)
10 was crystallized and separated into a crude titanium fluoride solution (crude TiF4).
Liquid) 9 is produced. FIG. 3 is a diagram showing the influence of temperature on the dissolved concentration of TiF4 and FeF3. As can be seen from Figure 3, the lower the melting temperature, the lower the dissolved concentration of FeF3, and the lower the cooling temperature during crystallization, the lower the crystallization rate of ferric fluoride crystals (FeFs 4.5 H2O)10. The amount is large and the load on post-processing can be reduced. Cooling temperature is 0-2
0°C is preferable; if the temperature is higher than 20°C, the separation efficiency of the ferric fluoride crystals 10 will decrease.

When the temperature is lower than 0°C, cooling efficiency decreases.

If ilmenite contains Fe” and Fe”,
The fluoride solution 4 also contains Fe2+ and Fe'', and F
eF2 and FeF3 are generated. When FeF2 is cooled, T
A double salt is formed with iF47, and ferric fluoride crystal (FeFs 4.5 Ha 0
) 10 and prevents the migration of TiF4 into the solution. For this reason, ferric fluoride crystal (FeFs 4.
5 Ha 0) Before cooling crystallization of 10, Fe2+ was converted to Fe'
It is effective to oxidize to +5 and prevent the formation of TiFeF6.6H20. Oxidation of Fe'' to Fe''4+5
is an oxidizing agent such as hydrogen peroxide, ozone, air, or oxygen6
This is done by adding or bringing into contact with the fluoride solution 4. In this way, Fe"+ is oxidized to Fe'",
By performing crystallization M8 of ferric fluoride crystals, the iron content in the fluoride solution 7 can be reduced to 1/2 to 1/10.

(3) Crystallization of ammonium fluoride salt A crude titanium fluoride solution (crude TiF4) obtained by crystallizing and separating 10 ferric fluoride crystals (F e Fz 4.5 Ha 0 )
ammonium fluoride solution (solution) adjusted in the post-process to 9.
NH4F solution) 26 to crystallize ammonium fluoride salts of titanium ammonium fluoride ((NH4)2 T i Fa) and ferric ammonium fluoride ((NH4's F e F b>). In order to adjust the water balance in the system during the analysis process, the mixed liquid is used as an evaporation source m11.
However, the ammonium fluoride salt crystallized by evaporation and concentration 11 of the mixed liquid, which is preferably recovered from moisture, is aged and becomes coarse particles, which facilitates crystallization separation 15. Concentrate 12
teeth.

By cooling as shown in FIG. 4, the ammonium fluoride salt can be crystallized and separated 15 more effectively.

The ammonium fluoride salt concentrate 12 thus obtained is crystallized and separated 15 to become an ammonium fluoride solution 17 containing an ammonium fluoride salt 16 and a dissolved ammonium fluoride salt. This ammonium fluoride solution 17 contains ammonia (NH
3> and hydrogen fluoride (HF) gas 24 are absorbed and mixed into a crude titanium fluoride solution (crude TiF4 liquid) 9 again as an ammonium fluoride solution (NH4,F solution) 26.

The water vapor 13 obtained in the evaporation concentration 11 is condensed, a part of the condensed water is discharged, and the remaining condensed water 14 is converted into ferric fluoride crystals (FeFs 4.5 Ha
0) TiF4. HF is absorbed, and further HF gas 32 and raw materials generated in the subsequent process are absorbed (F gas 34 is absorbed,
It is effective to adjust the hydrofluoric acid 3 and subject it to the fluoride dissolution 2 again. In addition, it is desirable that the washing water be cold water in order to prevent dissolution of ferric fluoride crystals (FeFs 4.5 Ha 0)10 during washing.In this way, water, hydrogen fluoride ( HF) is extremely effective in preventing fluorine from being discharged to the outside of the system, and in reducing pollution control costs and hydrogen fluoride (HF) raw material costs.

(4) Drying of ammonium fluoride salt, thermal decomposition of titanium ammonium fluoride ((NH4)2 T i F 6) and ferric ammonium fluoride ((NH4)3 F e F
Dry ammonium fluoride salt 16, which is the mixed salt of 6).
8 and in a dry gas stream containing no moisture, 30
Heat at 0-800°C. Upon heating, the ammonium fluoride salt 16 is thermally decomposed 19, and FeF3 becomes a solid 21.
TiF4. ) IP.

NH, is generated as a gas 20. The thermal decomposition reaction is as shown below.

(NH4)2　Ti　Fb→ Ti　F4+28F+2NH.

It is important that the dry gas does not contain moisture. As the dry gas, dry nitrogen, dry air, dry argon, etc. can be used. This is because when moisture is present in the gas, TiF4 undergoes a hydrolysis reaction at high temperatures, producing titanium oxide (T i O2) and reducing the yield of TiF4. The hydrolysis reaction is as shown below.

TiF4 +2H20→TiO2+4HF heating temperature is in the range of 300 to 800°C.

If the temperature is lower than 300°C, TiF will not sublimate completely, and if the temperature is higher than 800°C, FeF3 will sublimate to some extent. The heating temperature is more preferably 400 to 600°C.

(5) Condensation of titanium fluoride High purity titanium fluoride (TiF4) 23 is obtained by condensing and separating 22 the gases 20 of TiF4, HF, and NH3 at 20 to 280°C in a condenser. The condensation temperature ranges from 20 to 280°C.

If the temperature exceeds 280°C, TiF4 will sublimate.

HF will liquefy if it is lower than 20℃, 50-100
Titanium fluoride (TiF4
) 23 is condensed and separated, the gas 24 containing T(F, NHs) is absorbed into the ammonium fluoride solution 17 and used again as the ammonium fluoride solution 26, as described above.

(6) Thermal decomposition of FeF The FeFl solid 21 obtained as a residue by the thermal decomposition 19 of ammonium fluoride salt is separated by crystallization 8 from the fluoride solution 7.
The ferric fluoride crystal (FeFt 4.5
H2O)28 and in the presence of water, from 600 to
Heated at 1000°C. At this time, FeF3 is hydrolyzed to form iron oxide (Fe20-3)31 and hydrogen fluoride (
HF)32 is produced. When the heating temperature is lower than 600℃, the hydrolysis reaction does not occur, and when it is higher than 1000℃,
Iron oxide (Fez□5)31 where FeF3 sublimates
is discharged as a by-product, and hydrogen fluoride (HF) is produced by the ferric fluoride crystal (FeFi 4.5 H20
) 10, and is again subjected to ilmenite fluorination dissolution 2.

[Example] Example-1 Ilmenite ore from Western Australia (T i O2: 54.9%) was placed in a closed Teflon-lined reactor.

FeO: 19.5%, Fe203: 21
．． 6%>10kg and hydrogen fluoride (HF) 55% solution 17
．． 9 kg were mixed and stirred at 80° C. for 1 hour to obtain a fluoride solution. This fluoride solution was cooled to 35°C, and H
1.3 kg of zOz (35%) solution was added, stirred for 30 minutes, further cooled to 10°C, separated by crystallization, and F
e 13.6 kg of Ps 4.5 H20 cake and 15.6 kg of crude TiF4 liquid were obtained.

This FeFs 4.5 H20 cake was soaked in cold water at 5°C.
．． By washing with 3 kg, 11.4 kg of F e Fi 4.5 H20 crystals and 6.5 kg of washing liquid were obtained. In Table 1,
These compositions, T1 contents, and Ti migration rates in ores are shown.

Table 1 As shown in Table 1, 1. 99.0% of the T1 in the ilmenite ore has been transferred to the crude TiF4 solution and the cleaning solution.Fluorine containing the dissolved concentration of Ti(NH4)2Fb at 20°C is added to the mixture of the crude TiF4 solution and the cleaning solution. Ammonium chloride solution (NH4F: 37.6%, T
i (NH4)2 F b : 18.8%)16.
6 kg were mixed. Further, the mixture was concentrated under reduced pressure at 80° C. with stirring to evaporate 1.9 kg of water, cooled to 20° C., filtered and separated, and dried at 105° C. for 5 hours to obtain 14.8 kg of ammonium fluoride salt. . The composition of this ammonium fluoride salt is shown in Table 2.

Table 2 Next, this ammonium fluoride salt was placed in a Hastelloy thermal decomposition reactor and heated to 400°C in a nitrogen gas stream.
The outlet gas containing cracked gas was sent to a condenser whose temperature was adjusted to 80°C, and 48.2 kg of TiF was recovered. TiF48
．． 2 kg corresponds to 98% of titanium fluoride in 14.8 kg of ammonium fluoride salt. Furthermore, 96% of the Ti in the ilmenite ore was recovered in the form of T i F 4 . The outlet gas of the condenser was absorbed into the filtrate obtained by filtering and separating the ammonium fluoride salt, and after dehumidification, the gas was circulated to the thermal decomposition reactor again.

6 kg of FeF3 o remaining in the pyrolysis reactor and FeF1 4.5 H20 crystal 11 obtained by cooling crystallization
．． By mixing 4 kg and heat-treating at 700°C with air as a carrier gas, p e 2034,
4 kg was obtained as residue. The outlet gas at this time is sent to a condenser at 5°C, and a hydrofluoric acid solution containing 3.3 kg of hydrogen fluoride is
．． I got 6 kg.

Example-2 Titanium ammonium fluoride was dried at 105°C for 20 hours. After loading dried titanium ammonium fluoride 100.0g into a tube furnace, the inside of the furnace was heated to about 500° C. while passing dry air through a calcium chloride tube at a rate of 1 liter per minute. The outlet gas of the tube furnace was passed through a condenser whose temperature was adjusted to 50° C., and 61.5 g of titanium fluoride was recovered, which was a zero recovery rate of 98%.

As a comparative example, an experiment was conducted using air without ventilation through the calcium chloride tube, that is, atmospheric air. First, titanium ammonium fluoride was dried at 105° C. for 20 hours. After loading 100.0 g of dried titanium ammonium fluoride into a tubular furnace, the inside of the furnace was heated to about 500° C. in an air stream. The outlet gas is passed through a condenser whose temperature is controlled to 50°C.
48.0g of titanium fluoride was recovered, and 9.4g of titanium oxide remained in the furnace. The recovery rate of titanium fluoride was 77%.

Example-3 14.8 kg of ammonium fluoride salt having the composition shown in Table 2 prepared in exactly the same manner as in Example-1 was placed in a Hastelloy thermal decomposition reactor, and dried by venting through a calcium chloride tube. The outlet gas containing zero decomposition gas heated to 400°C in an air stream was sent to a condenser whose temperature was adjusted to 80°C, and 48.2 kg of TiF was recovered. In this way, even when dry air was used as the drying gas, 98% of the titanium fluoride in 14.8 kg of ammonium fluoride salt could be recovered.

[Effects of the Invention] As described above, according to the present invention, ore can be almost completely dissolved by reacting an iron-containing titanium raw material such as ilmenite with a hydrofluoric acid-containing liquid at 40°C or higher, and the ore can be dissolved. Almost all of the titanium in it can be produced as titanium fluoride. For this reason, the reaction production rate of titanium fluoride is extremely high, and the final recovery rate as titanium fluoride is 95%.
That's all.

Furthermore, according to the present invention, it is not necessary to use expensive organic solvents such as those used in solvent extraction methods for separating iron from a fluorinated solution of iron-containing titanium raw materials, and the dissolved concentration of titanium fluoride and iron fluoride can be reduced. By combining crude separation using crystallization separation that takes advantage of the difference in temperature and purification separation that takes advantage of the difference in sublimation temperature between titanium fluoride and iron fluoride, it is possible to purify and separate titanium fluoride at a lower cost than the solvent extraction method. .

Further, the iron fluoride crystals separated by crystallization and the iron fluoride generated by heat treatment are hydrolyzed, and fluorine can be recovered as hydrogen fluoride. In addition, ammonia and hydrogen fluoride produced by thermal decomposition of ammonium fluoride salts are also recovered, and fluorine other than the amount consumed by the reaction is recycled within the system, which is very effective in terms of cost and pollution prevention.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the flow of the method for producing titanium fluoride according to the present invention, Figure 2 is a diagram showing the influence of reaction time and reaction temperature on the fluorination rate, and Figure 3 is a diagram showing the dissolved concentration of TiF4 and FeF3. FIG. 4 is a diagram showing the influence of temperature on the dissolved concentration of titanium ammonium fluoride ((NH4)2T i F6). 1...Iron-containing titanium raw material, 2...Fluoride dissolution, 3
... Hydrofluoric acid, 4... Fluoride solution, 8... Crystallization separation of ferric fluoride crystals (F e Fi 4.5 H20), 9... Crude titanium fluoride solution, 10... Ferric fluoride crystal <FeFs 4.5 H2O), 11- Evaporation concentration, 15... Crystallization separation of ammonium fluoride salt,
16... Ammonium fluoride salt, 17... Ammonium fluoride solution, 18... Drying, 19... Pyrolysis,
20...Ti F4. HF, NH3 gas, 21...
- FeF3 solid, 22... condensation separation, 23... titanium fluoride.

Claims (1)

[Claims] (1) A titanium raw material containing iron is dissolved in a solution containing hydrofluoric acid to produce a fluoride solution, and by cooling the fluoride solution, ferric fluoride crystals are crystallized and separated to produce crude fluoride. Ammonium fluoride salts [(NH_4)_2TiF_6 and (NH_4) are prepared by forming a titanium solution, mixing the crude titanium fluoride solution with an ammonium fluoride solution, and concentrating by evaporation, cooling, or a combination thereof.
Mixed salt of _3FeF_6] was crystallized and separated, and the ammonium fluoride salt was dried and heated to 300 to 800
Ferric fluoride (FeF_3) is thermally decomposed at ℃ as a solid.
, generate TiF_4, HF, and NH_3 as gases,
The gas is condensed at 20-280°C to form TiF_4 and HF.
- A method for producing titanium fluoride, which is characterized by condensation separation into NH_3 gas.