JPH01115820A - Production of niobium hydroxide of tantalum hydroxide - Google Patents

Abstract

PURPOSE:To obtain niobium hydroxide or tantalum hydroxide having excellent filtering characteristics and a small content of fluorine, by blending an alkali aqueous solution containing CO2 with a specific amount of an aqueous solution of Nb or Ta fluoride to crystallize niobium hydroxide or tantalum hydroxide in an alkali side. CONSTITUTION:An alkali aqueous solution (e.g. ammonia water) containing CO2 is blended with an aqueous solution of niobium or tantalum fluoride (e.g. aqueous solution of niobium fluoride) or an aqueous solution of niobium or tantalum oxalate (e.g. aqueous solution of niobium oxalate) in the molar ratio of CO2/Nb or CO2/Ta of 0.1-3. Then crystallization is carried out at pH>=8 to give niobium hydroxide or tantalum hydroxide. The prepared niobium hydroxide or tantalum hydroxide has <=about 20ppm fluorine content and is preferably used as a raw material for wet synthesis for electric material or as a raw material for producing oxides.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improved method for producing niobium hydroxide or tantalum hydroxide, and more particularly, to a raw material for wet synthesis of electronic materials and for producing oxides. suitable as a raw material for
The present invention relates to a method for producing niobium hydroxide or tantalum hydroxide with low fluorine content.

[Prior Art] Niobium oxide or tantalum oxide is a raw material such as niobium metal or tantalum metal, niobium carbide, tantalum carbide,
Used as additives for optical lenses, raw materials for electronic materials, etc.
Demand for high-purity products as raw materials is increasing. Generally, niobium oxide or tantalum oxide is produced by decomposing the raw material ore with hydrochloric acid according to a known method, adding an alkali such as ammonia to a fluoride complex salt solution of niobium or tantalum, precipitating the metal hydroxide, and drying this. , a metal oxide is obtained by firing. However, in the above method,
A large amount of fluorine remains. Also, since niobium or tantalum hydroxide is very fine by normal methods,
The problem was that the processes such as filtration and drying were complicated and required expensive equipment.

As a way to improve these problems,
Publication No. 0354 discloses water with good filterability, which is characterized in that ammonium carbonate or ammonium bicarbonate is added to a fluoride complex salt solution of niobium or tantalum, and then the precipitate obtained by heating is calcined according to a conventional method. A method for producing niobium oxide or tantalum hydroxide is disclosed. However, in this method, the filterability is improved,
Although the fluorine content has also been reduced, the wet processing stage still contains several percent fluorine.

On the other hand, in JP-A-51-10197, when a niobium fluoride or tantalum fluoride aqueous solution is reacted with ammonia to obtain a hydroxide, the fluorine in the hydroxide is treated under conditions of pH 9 or higher. Disclosed is a method for producing niobium hydroxide or tantalum hydroxide, which comprises removing niobium hydroxide or tantalum hydroxide. In this method 2, the fluorine content is reduced to 0.6%, but the hydroxide particles are fine and difficult to filter, and if crystallization is performed in an area with too high a pH, a large amount of fluorine will be produced. of dilute ammonia water is discharged, which is not economical.

[Problems to be solved by the invention] As described above, when crystallizing hydroxide from an aqueous solution of fluorine-containing niobium fusilide or niobium shearate, fluorine is contained in the particles on the acidic side. The amount of residual fluorine hardly changes, and although the amount of fluorine decreases with washing in the case of alkaline side, the fluorine produced becomes fine and gel-like, making the washing itself very difficult.

In order to solve these problems, the present invention aims to produce particles that are crystallized with alkaliside and have good filterability.

[Means for Solving the Problems] In order to achieve the above object, the present inventors conducted intensive studies and found that an alkaline aqueous solution containing CO2 was used, and a niobium or tantalum fluoride aqueous solution or By adding an oxalate aqueous solution and crystallizing the hydroxide while always keeping the solution alkaline, it is easy to filter and wash (niobium hydroxide or hydroxide particles with a very low fluorine content of 200 ppm or less) It was discovered that tantalum can be obtained, and the present invention was achieved.

That is, in the present invention, the molar ratio of COz/Nb or CO2/Ta is 0.1 in an alkaline aqueous solution containing CO2.
A method for producing niobium hydroxide or tantalum hydroxide, which comprises adding a niobium or tantalum fluoride aqueous solution or an oxalate aqueous solution so that the niobium hydroxide or tantalum hydroxide is 3.0, and crystallizing at P) 18 or more. .

The present invention can be carried out either batchwise or semi-continuously.

In the semi-continuous method, a molar ratio of CO2/Nb or 0/Ta is added to an alkaline aqueous solution containing CO2.
．． An aqueous solution of fluoride or oxalate of niobium or tantalum and an aqueous alkali solution are added at the same time so that the ratio is 1 to 3.0. In this method, the initial pH can be set freely and fluctuations in pH can be minimized, resulting in particles that are uniform and have good filterability.

On the other hand, in the batch method, niobium or tantalum fluoride or oxalate is added to an alkaline aqueous solution containing CO2 so that the molar ratio of COz/Nb or CO2/Ta is 0.1'-3.0. Add aqueous solution to pH
8 or higher to crystallize hydroxide.

In this case, the pH of the aqueous solution is initially high, and as the reaction progresses, the pH decreases, so the uniformity of the particles is somewhat different from that of the semi-continuous method, but the defluorination effect is almost the same.

Here, one of the reasons why defluorination is more effective at pH 8 or higher
One reason is that, for example, niobium and fluorine combine strongly on the acidic side, producing (NHa)Nb0F6, and it is thought that such compounds decompose on the alkaline side to become fluorine ions. .

Furthermore, when CO□ is included in an alkaline solution, the amount of dissolved carbon in the hydroxide increases and the crystallization rate also decreases, so the hydroxide crystallizes slowly and the particles become larger.

At this time, it is necessary to pay close attention to the addition rate and stirring rate so that the added solution is sufficiently dispersed and does not become locally acidic.

The amount of CO2 blown in the present invention is in the molar ratio of CO2/Nb or CO2/Ta from 0.1 to 3.0, preferably from 0.2 to 2.0. If it is less than 0.1, there is almost no effect on coarsening the particles, and if it exceeds 3.0, the amount of dissolved niobium hydroxide or tantalum hydroxide increases and the amount of uncrystallized substances increases, making it uneconomical. I don't like it.

In addition, P at the time of crystallization should be 8 or more, but if it is set too high, a large amount of alkali such as ammonia will be required, which is economically disadvantageous, so the more preferable range is PH8.5. ~1165.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 208.3 g of ion-exchanged water was placed in a Teflon container of No. 11, and 98.0 g of ammonia water of 25 wtχ was added.
29.7 g of CO2 gas was blown into the reactor to create a Co2-containing alkaline aqueous solution. While stirring this liquid, CO2/Nb
Niobium fluoride aqueous solution (N
byu0,1 conversion 10-tχ) 320g and 25wt! 144 g of aqueous ammonia was added at the same time, and the addition was completed in 1 hour to crystallize coarse niobium hydroxide.

The pH at this time was 9.5.

Thereafter, this precipitate was filtered and washed, dried at 120''C for 20 hours, and analyzed for fluorine. Calculated as F. As a result, the fluorine content was 85pp.
Maro and very few.

Example 2 Experiments and analyzes were conducted under the same conditions as in Example 1, except that an alkaline aqueous solution was prepared using 326.9 g of ion-exchanged water, 7 g of 25 wt x ammonia water, and 2.1 g of CO2 gas. The molar ratio of COz/Nb at this time is 0.2,
The pH at the time of crystallization was 9.6. As a result of such treatment, the fluorine content in the obtained hydroxide was 190 pp-.

Example 3 Experiments and analyzes were conducted under the same conditions as in Example 1, except that an alkaline aqueous solution was prepared using 290.0 g of ion-exchanged water, 35 g of 25 wtX ammonia water, and 10.6 g of CO□ gas. The COz/Nb molar ratio at this time was 1.0, and the pH at the time of crystallization was 9.5. As a result of such treatment, the fluorine content in the obtained hydroxide was 150p.
It was a haze.

Example 4 Experiments and analyzes were conducted under the same conditions as in Example 1, except that an alkaline aqueous solution was prepared using 244.8 g of ion-exchanged water, 70 g of 25IIltz noammonia water, and 21.2 g of CO2 gas. The molar ratio of CO2/Nb at this time is 2.0
The pH at the time of crystallization was 9.5. As a result of such treatment, the fluorine content in the obtained hydroxide is 95P.
It was Pl.

Example 5 An alkaline aqueous solution was prepared with 384.0 g of ion-exchanged water, 85 g of 25111tz noammonia water, and 10.6 g of CO2 gas, and only 320 g of a niobium fluoride aqueous solution (the concentration was the same as in Example 1) was added to this solution. An experiment was conducted in the same manner as in Example 1, and analytical results were obtained.

The CO2/Nb molar ratio at this time was 1.0, and the pH at the time of crystallization was 9.0. As a result of such treatment, the fluorine content in the obtained hydroxide was 190 Pρ1.

Example 6 An alkaline aqueous solution was prepared with 384.0 g of ion-exchanged water, 85 g of ammonia water of 25 wtx, and 10.6 g of CO2 gas, and to this solution was added a niobium Scherate aqueous solution containing 1.1z of fluorine (the concentration was the same as that of Example 1). Same) 320g
An experiment was carried out in the same manner as in Example 1, with the addition of only 100% of the sample, and analytical results were obtained.

The CO2/Nb molar ratio at this time was 1.0, and the pH at the time of crystallization was 9.0. As a result of such treatment, the fluorine content in the obtained hydroxide was 80 ppm.

Example 7 36.7 kg of ion-exchanged water was placed in a 1001 dilite tank, 1.2 kg of 25 wtχ ammonia water was added, and 4 kg of ammonium bicarbonate (purity 97-tχN) was added to prepare a CO2-containing alkaline aqueous solution.

Add to this solution a niobium fluoride aqueous solution (concentration is the same as in Example 1).
31.0 kg and 7.1 kg of ammonia water with 25-tχ
were added at the same time with stirring, and the addition was completed in 2 hours. The pH at this time was 9.3 and it was light.

This precipitate was filtered and separated using a centrifuge, and fluorine was analyzed in the same manner as in Example 1.

As a result, the fluorine content was 160 ρpm.

When the precipitate was further washed with 20 times the amount of ion-exchanged water, the fluorine content was further reduced to 48 ρpl.

Example 8 An experiment was conducted in the same manner as in Example 1 using tantalum fluoride (T 820 g equivalent 10 wtZ) to obtain tantalum hydroxide. Analysis was conducted in the same manner as in Example 1, and the fluorine content was found to be 155 PP. Further, the pH at the time of crystallization was 9.5.

Example 9 Using the same tantalum fluoride as in Example 8, an experiment was conducted under the same conditions as in Example 2, and the fluorine content in tantalum hydroxide was 90 ppm.

Moreover, P)l at the time of crystallization was 9.5.

Example 10 Using the same tantalum fluoride as in Example 8, an experiment was conducted under the same conditions as in Example 3. The fluorine content in tantalum hydroxide was 165 ρpm, and the pH at the time of crystallization was 9. It was 0.

Example 11 Oxalic acid tank solution containing 0.9χ fluorine (T
An experiment was conducted under the same conditions as in Example 4 using 10wtZ (converted to 05). The fluorine content in tantalum hydroxide was 70 ppm.

Moreover, P)I at the time of crystallization was 9.0.

Example 12 Using the same tantalum fluoride as in Example 8, an experiment was conducted under the same conditions as in Example 5. The fluorine content in the tantalum hydroxide was 150 pp-, and the pH at the time of crystallization was 9. It was .0.

When this hydroxide was washed in the same manner as in Example 5, the fluorine content was reduced to 41 ρpl.

Comparative Example 1 11 500 g of ammonium carbonate was added to 640 g of an aqueous niobium fluoride solution (N% 0° conversion 5 wtχ) and heated to 80° C. After 6 hours, crystallization of niobium hydroxide was completed. When this was analyzed under the same conditions as in Example 1, the fluorine content was 5χ. Moreover, PR at the time of crystallization was 7.3.

Comparative Example 2 11 640 g of niobium fluoride aqueous solution (concentration is the same as Comparative Example 1) was placed in a Teflon container, and 25 wt x ammonia water was added until the pH reached 7.8 to crystallize niobium hydroxide. At this time, the fluorine content was 13.1z.

Comparative Example 3 11 Put 336 g of ion-exchanged water in a Teflon container, add 320 g of niobium fluoride solution (fi degree is the same as Comparative Example 1) and 144 g of 25 wtZ ammonia water at the same time, and add over 1 hour while stirring well. finished.

The pH at the time of crystallization is 8.5. The fluorine content at this time is 0
．． It was 2χ.

Comparative Example 4 An experiment was conducted under the same conditions as Comparative Example 1 using an aqueous tantalum fluoride solution (5 wtx in terms of Ta and Ot).

The fluorine content of the obtained tantalum hydroxide is 5.1! Met. The pH during crystallization is 7.3.

Comparative Example 5 An experiment was conducted under the same conditions as Comparative Example 2 using an aqueous tantalum fluoride solution (once was the same as Comparative Example 4). The fluorine content of the obtained tantalum hydroxide is 12.8χ, and the PFI at the time of crystallization is 8.0.

Comparative Example 6 Tantalum fluoride aqueous solution (Ta 0.! - converted to 10wt!)
An experiment was conducted under the same conditions as Comparative Example 2. The fluorine content of the obtained tantalum hydroxide was 0x. PR at the time of crystallization is 9.0.

[Effects of the Invention] As described above, the present invention uses a very simple method to produce niobium hydroxide or tantalum hydroxide, which has good filtration properties and has a significantly lower fluorine content than the conventional method, which has a fluorine content of 200 ρpl or less. can be obtained, and the hydroxide content can be reduced to 50 ppm or less by further washing.

Claims (1)

[Claims] CO_2/N to an alkaline aqueous solution containing CO_2
Hydroxylation characterized by adding a niobium or tantalum fluoride aqueous solution or an oxalate aqueous solution so that the molar ratio of b or CO_2/Ta is 0.1 to 3.0, and crystallizing at a pH of 8 or higher. Method for producing niobium or tantalum hydroxide.