JP2000203841A - Dissolving extraction for alloy containing tantalum and/ or niobium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of highly productive dissolving extraction for alloys containing tantalum and/or niobium, improved in the recovery of tantalum and/or niobium with a small amount of hydrofluoric acid to be used. SOLUTION: This method of the dissolving extraction of tantalum and/or niobium from alloys containing the element(s) with hydrofluoric acid or its mixture with sulfuric acid comprises the following process: a specified amount of water in a reaction tank is charged with a necessary amount of pulverized alloys containing tantalum and/or niobium followed by treatment with sodium hydroxide, the resulting liquor thus treated is subjected to solid/liquid separation, the resultant insoluble product is then treated with a mineral acid other than hydrofluoric acid to dissolve impurity metals other than the tantalum and/or niobium in the mineral acid; subsequently, a solid/liquid separation is carried out, and the resultant remaining insoluble product is put to dissolving extraction with hydrofluoric acid or its mixture with sulfuric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to tantalum and / or tantalum.
Alternatively, the present invention relates to a dissolution extraction method for economically and efficiently recovering these metal elements from a niobium-containing alloy.

[0002]

2. Description of the Related Art Tantalum has a wide range of uses, corrosion resistance,
Because of its excellent heat resistance, it is used in various chemical devices such as distillation towers, autoclaves, heat exchangers, and spinning nozzles for chemical fibers for the chemical industry. In general, a tantalum oxide film has a characteristic called a valve action (a characteristic in which the electrode functions as a dielectric if the electrode is a positive electrode, but does not operate as a dielectric when the electrode is a negative electrode, that is, a rectifying characteristic). Therefore, it is used as an electrode material for electrolytic capacitors, and is used in transport equipment, electronic equipment, electronic control equipment, and the like. Furthermore, tantalum carbide is used as a material for carbide cutting tools.
Tantalum oxide is used as an additive for optical lenses, and tantalum is very important and its demand is increasing.

[0003] Niobium is used as a steel additive because it has the effect of stabilizing carbon in steel and preventing intergranular corrosion, and this is the largest use. In addition, a niobium alloy has been put to practical use as a conductive tube attached to a lamp light emitting portion of a high-pressure sodium lamp, and is used as a superconducting material or an additive element of a superalloy.

There are several methods for producing tantalum and / or niobium oxide from a tantalum and / or niobium-containing alloy, but a hydrofluoric acid dissolution-solvent extraction method is generally used.

In the dissolution and extraction of a tantalum-containing alloy or a niobium-containing alloy with hydrofluoric acid or a mixed acid thereof with sulfuric acid, hydrogen gas is used as shown in the following reaction formulas (1), (2) and (3). Occurs.

M + 5HF → M ⁵⁺ + 5F ⁻ + 5 / 2H ₂ … (1) Here, M represents a metal element.

[0007] Hydrogen gas constitutes a very wide explosion composition of 7-72% with respect to air, so tantalum and / or
Alternatively, a method of directly dissolving and extracting a niobium-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid is dangerous and has a problem in terms of safety.

In order to solve these problems, a conventional method is disclosed in Japanese Patent Publication No. 5-20490 and Japanese Patent Application No.
No. 263288 has been proposed. The method described in Japanese Examined Patent Publication No. 5-249090 eliminates the risk of explosion by eliminating the generation of hydrogen in the dissolution extraction step, and also increases the recovery rate of niobium by preventing passivation of niobium. The purpose of this method is to dissolve and extract niobium using a mixed acid of hydrofluoric acid and sulfuric acid after burning and oxidizing a niobium-containing alloy.

The method described in Japanese Patent Application No. 10-263288 occurs when a tantalum and / or niobium-containing alloy is directly dissolved and extracted with hydrofluoric acid or a mixed acid thereof with sulfuric acid without burning and oxidation. The purpose is to suppress the hydrogen gas to below the explosion composition and to operate safely. After charging a required amount of tantalum and / or niobium-containing alloy into a predetermined amount of water in the reaction tank, This is a method in which a mixed acid of sulfur and sulfuric acid is continuously added and dissolved while suppressing the generated hydrogen gas.

These methods require a large amount of hydrofluoric acid in order to dissolve all the constituent metals of the alloy of the tantalum and / or niobium-containing alloy as the raw materials in the processing solution. When recovering tantalum and / or niobium by solvent extraction, it is necessary to precipitate and precipitate dissolved impurity metals, particularly iron, which may be precipitated in the solvent extraction step, and remove them as residues by filtration and separation. In this case, since tantalum and niobium partially migrate to the impurity metal precipitate side, the recovery rate of tantalum and niobium decreases. Furthermore, when the residue is washed with washing water to recover tantalum and niobium in the washing water, there are problems such as an increase in the amount of the treatment liquid to be subjected to the solvent extraction step, and a decrease in production efficiency in the solvent extraction step.

Therefore, when there are many impurity metals other than tantalum and niobium to be dissolved and extracted, the amount of hydrofluoric acid used is small, the recovery of niobium and tantalum is high, and the productivity of niobium and tantalum is excellent. The emergence of the dissolution extraction method is strongly demanded.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for dissolving and extracting a tantalum and / or niobium-containing alloy with high productivity, which uses a small amount of hydrofluoric acid and improves the recovery of tantalum and niobium. To provide.

[0013]

The present invention has the following features. In a method of dissolving and extracting tantalum and / or niobium in a tantalum and / or niobium-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, pulverized tantalum and / or niobium are introduced into a predetermined amount of water in a reaction vessel. After charging the required amount of the alloy, first treat it with caustic soda (NaOH), separate the treatment liquid into solid and liquid, and treat the resulting insoluble product with a mineral acid other than hydrofluoric acid to remove tantalum and niobium. Eluted impurity metals in mineral acid, then perform solid-liquid separation, and dissolve and extract the remaining insoluble product obtained with hydrofluoric acid or a mixed acid thereof with sulfuric acid. And / or a method for dissolving and extracting a niobium-containing alloy.

Hereinafter, the present invention will be described in detail. First,
FIG. 1 shows a process for producing tantalum oxide or niobium oxide using a conventional tantalum and / or niobium-containing alloy as a starting material. A general example using ferronium as a raw material among niobium-containing alloys will be described with reference to FIG. 1. First, in order to increase the dissolution rate of ferroniob, coarsely pulverized by a crusher such as a jaw crusher and put into a melting tank. Dissolve the metal component with 55% hydrofluoric acid (HF). Next, sulfuric acid (H ₂ SO ₄ ) is added to adjust the acid concentration of the solution, which is filtered with a filter press, and the undissolved residue is filtered to obtain a clean solution and subjected to solvent extraction. Next, when this aqueous solution having a high acid concentration is brought into sufficient contact with an organic solvent MIBK (abbreviation for methyl isobutyl ketone), niobium becomes M
Extracted into IBK, impurities remain in raffinate. Next, MIBK containing niobium is back-extracted with dilute sulfuric acid to obtain a purified aqueous solution of niobium. Then, aqueous ammonia (NH ₄ OH) is added to precipitate hydroxide, which is filtered, dried, and finally placed in a furnace. Calcination gives niobium oxide.

The present invention relates to a conventional process shown in FIG.
The present invention relates to an improvement in a melting step between a pulverizing step and a liquid adjusting step, in which a finely divided tantalum and / or niobium-containing alloy is treated with caustic soda, and then treated with a mineral acid other than hydrofluoric acid. A method characterized by the fact that most of the impurity components can be eluted into the mineral acid to obtain purified tantalum or niobium insolubles.

FIG. 2 shows a process chart of a method for dissolving and extracting a tantalum and / or niobium-containing alloy according to the present invention. 30% iron as tantalum and / or niobium containing alloy
A description will be given of an example in which a raw material containing a certain amount is used. First, a Ta-containing ferroniobium (Fe-Ta / N
b) is coarsely crushed with a jaw crusher and further finely pulverized with a wet ball mill.
With an aqueous solution of caustic soda. The concentration of caustic soda is preferably 100-600 g / l, more preferably 300
~ 500 g / l is suitable. When the concentration of caustic soda in the aqueous caustic soda solution is less than 100 g / l, the reaction takes too much time, and the economical efficiency deteriorates. On the other hand, when the concentration is more than 600 g / l, the viscosity is high and handling becomes difficult. Treatment of the alloy powder with caustic soda destroys the alloy structure and causes tantalum and / or
Alternatively, niobium is a reaction product insoluble in mineral acids other than caustic soda and hydrofluoric acid, and Fe is a reaction product insoluble in caustic soda and soluble in mineral acids, and the hydrofluoric acid Dissolving in other mineral acids, that is, removing Fe. Part of NaOH is Na ₂ C
It can be replaced by O ₃ , NaHCO ₃ .

Next, the treated liquid is subjected to solid-liquid separation by filtration, and separated into a filtrate and an insoluble product. Insoluble products include NaO
There are reaction products such as Ta, Nb, and Fe that do not dissolve in H. This insoluble product is treated with a mineral acid other than hydrofluoric acid such as hydrochloric acid or sulfuric acid, and most of the impurity components Fe
Etc. are eluted in mineral acids. In this Fe removal step, Fe is removed, but Ta / Nb remains undissolved.

Thereafter, this solution is filtered to separate it into a FeCl ₂ liquid or a FeSO ₄ filtrate and an undissolved substance containing Ta / Nb. The FeCl ₂ liquid or the FeSO ₄ liquid is neutralized and wasted. On the other hand, the undissolved material containing Ta / Nb is hydrofluoric acid, in which Ta / Nb is dissolved, and then the dissolved residue is removed by filtration to obtain a high-quality Ta / Nb solution. This Ta / Nb liquid is transferred to a solvent extraction step through a liquid adjustment step shown in FIG.

[0019]

The present invention will be further described below with reference to examples and comparative examples. Example 1 Ta-containing ferroniobium (Fe-Ta / Nb) 200 g
(Fe 29%, Ta 4.5%, Nb 41.2%) was roughly pulverized with a jaw crusher and then finely pulverized with a wet ball mill to obtain a Fe-Ta / Nb slurry. This Fe
-Ta / Nb slurry (slurry concentration 1000 g / l)
And 200 ml of an aqueous NaOH solution (concentration: 100 g / l) were placed in a reaction vessel (volume: 1 liter), and the mixture was stirred at a liquid temperature of 75 ml.
Warmed to ° C.

Next, 735 g / l of NaOH was added to the reaction vessel.
As a result of adding 210 ml little by little over 160 minutes, the concentration in terms of NaOH in the reaction tank reached 425 g / l. N
The stirring was continued while maintaining the liquid temperature at 75 ° C. for 255 minutes after the completion of the aOH addition, and the whole amount was separated by filtration with a filter press. The obtained insoluble product was put into a reaction vessel (volume: 5 l), then 2,000 ml of 4NH ₂ SO ₄ was added to the reaction vessel, and H ₂ SO ₄ was further added to pH 1, and
While maintaining at 1, stirring was continued for 60 minutes to dissolve iron in the aqueous sulfuric acid solution. The reaction-terminated liquid is sent to a filter press, separated by filtration, and filtrated (FeSO ₄ aqueous solution) 300
0 ml (18.8 g / l of Fe) and 352.8 g (212.0 g of Dry) of undissolved matter (de-Fe cake) were obtained.

The de-Fe cake 21 thus obtained is obtained.
2.0 g (dry base) was placed in a reaction tank (volume: 0.5 l) into which 0.1 l of water had been impregnated.
0.14 l of HF was added little by little, and the mixture was heated to 60 ° C. and stirred for 60 minutes while maintaining the temperature.
Dissolution extraction into F was performed.

The whole amount of the obtained dissolved extract was filtered through filter paper to obtain 0.44 liter of the filtrate (185 g / l Nb, Ta20).
g / l, 21 g / l Fe) and 12.7 g of dissolved residue (Fe
0.3%, Nb 13.6%, Ta 1.6%). The recovery rates of Ta and Nb recovered by dissolution extraction were Nb9
7.9% and Ta 97.6%.

Comparative Example 1 200 g of an Fe-Ta / Nb alloy roughly pulverized by a jaw crusher was placed in a reaction tank (volume: 1 liter) filled with 0.2 liter of water, and HF was added little by little while stirring and mixing. Dissolution extraction was performed over time. The amount of 55% HF used was 0.24 l.

Then, H ₂ SO ₄ was added to the obtained dissolved extract to adjust the H ₂ SO ₄ concentration to 4N, and the whole was filtered with a filter press to obtain 1.1 L (Nb) of the filtrate.
70 g / l, Ta 7.6 g / l, Fe 30 g / l) and 100 g of dissolved residue (dry basis) were obtained. Dissolution residue is Fe
25.1%, Nb 4.8%, Ta 0.6%, and T
The recovery rates of a and Nb were 93.4% for each Nb and 92.9% for Ta.
Met.

Example 2 100 g of Fe-Ta / N each finely pulverized by a ball mill
b alloy (Fe 29%, Ta 4.5%, Nb 41.2%)
Was poured into an aqueous solution of NaOH to perform a NaOH treatment.
The NaOH treatment was performed by changing the concentration, the amount of addition, the liquid temperature, and the treatment time of NaOH.

After the NaOH treatment under each of the above conditions, the whole reaction solution was filtered and separated by a filter press to obtain an insoluble product. The obtained insoluble product is placed in a reaction tank (volume: 3 l).
H ₂ SO ₄ was added until pH 1 was maintained, and the iron in the insoluble product was eluted in sulfuric acid. Thereafter, the whole liquid was separated by filtration with a filter press to obtain an undissolved substance (de-Fe cake), and the amount of Fe in each de-Fe cake was analyzed and measured, and the de-Fe ratio was determined. Table 1 shows the results.

[0027]

[Table 1]

Example 3 Fe-Ta / Nb (Fe29) finely pulverized by a ball mill
%, Ta 4.5%, Nb 41.2%) was added little by little to 44 l of a 500 g / l aqueous solution of caustic soda, added over 10 hours, and treated with NaOH while maintaining the liquid temperature at 75 ± 5 ° C. Was done.

After the completion of the Fe-Ta / Nb injection, a sample of 0.1 L was taken every elapse of the NaOH treatment time, and the sample was separated by filtration through filter paper to obtain an insoluble product. The substance was put into a reaction tank (volume of 1 l), and H ₂ SO
₄ was added until pH 1 could be maintained, and the Fe in the insoluble product was eluted in the sulfuric acid. Thereafter, the whole liquid was separated by filtration with filter paper to obtain an undissolved substance (de-Fe cake).
The amount of Fe in the e-cake was analyzed and measured. The result is shown in FIG.
Shown in

Example 4 25 kg of Fe-Ta / Nb finely pulverized by a ball mill
(29% of Fe, 4.5% of Ta, 41.2% of Nb) were added little by little to 44 liters of 500 g / l NaOH caustic soda, and the mixture was added thereto over 10 hours while maintaining the liquid temperature at 75 ± 5 ° C. and further adding 14 parts. Stirring was continued for hours.

[0031] The reaction-terminated liquid was filtered with a total volume of filter press to obtain a insoluble product, insoluble product obtained 5 divided, placed each reaction vessel (volume 100l), H ₂
Elution of Fe was carried out by changing the concentration of SO ₄ and the amount of addition, and undissolved matter (de-Fe cake) was separated by filtration with a filter press.
And the Fe content in the obtained de-Fe cake was analyzed and measured,
The Fe removal rate was determined. The result is shown in FIG.

Example 5 A test was performed under the same conditions as in Example 4 except that HCl was used instead of H ₂ SO ₄ . 25 kg of Fe-Ta / Nb (Fe 29%, Ta
4.5%, Nb 41.2%) at a concentration of 500 g / l Na
OH was added little by little to 44 liters of caustic soda, and charged over 10 hours.
Stirring was continued for 4 hours.

[0033] The whole reaction solution was filtered with a filter press to obtain an insoluble product. The obtained insoluble product was divided into 5 parts, each of which was put into a reaction tank (capacity: 100 l).
Then, Fe was eluted by changing the concentration and the amount of addition, and separated by filtration with a filter press to obtain an undissolved substance (de-Fe cake). The Fe content in the obtained de-Fe cake was analyzed and measured.
e The removal rate was determined. The result is shown in FIG.

[0034]

Advantages of the Invention The conventional method uses Ta / Nb
All of the other impurity metals are dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid. Therefore, a large amount of expensive hydrofluoric acid is required. After removal by treatment (NaOH treatment, deironing treatment), Ta / Nb is dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, so that the amount of hydrofluoric acid used is small.
In particular, the difference in the effect is remarkable in an alloy having a large amount of Fe as compared with Ta / Nb, such as an Fe-Ta / Nb alloy. 2. The impurity metals, particularly iron, in the raw material are neutralized and discarded as waste, but the Fe-containing filtrate from the de-Fe treatment step does not contain F, so the C is not treated during the filtrate treatment.
The F treatment with salt a becomes unnecessary, and the amount of neutralized waste is greatly reduced as compared with the conventional method.

3. In the present invention, since Ta / Nb in the raw material alloy becomes a product insoluble in mineral acids other than hydrofluoric acid by the NaOH treatment, only impurities such as Fe are dissolved and extracted in the mineral acid treatment. There is no transfer of Ta / Nb, and the recovery rate of Ta / Nb can be increased. 4. There is no transfer of Ta / Nb to the impurity side, and there is no generation of recovered water due to residue washing for recovery of Ta / Nb which has been transferred to impurity residues such as Fe which has been conventionally performed. Increases the concentration of Ta / Nb, thereby improving the productivity. 5. Since the filtrate in the filtration step after the NaOH treatment does not contain much impurities, the NaOH used in the NaOH treatment step
It can be reused as water for dissolution or as a neutralizing agent for wastewater treatment of Fe salt solutions.

[Brief description of the drawings]

FIG. 1 is a process chart for producing tantalum oxide / niobium oxide from a conventional tantalum and / or niobium-containing alloy by an oxidative roasting method.

FIG. 2 is a process diagram of a method for dissolving and extracting an iron-containing tantalum / niobium alloy according to the present invention.

FIG. 3 shows F in NaOH treatment in Example 3 of the present invention.
Time from the end of charging the e-Ta / Nb alloy and F
It is a graph which shows the relationship with e content rate.

FIG. 4 is a graph showing the relationship between the use equivalent of H ₂ SO ₄ and the Fe removal rate in Example 4.

FIG. 5 is a graph showing the relationship between the HCl equivalent and the Fe removal rate in Example 5.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshio Sohama 1-1-1, Nihonbashi Muromachi, Chuo-ku, Tokyo Mitsui Kinzoku Mining Co., Ltd. F-term (reference) 4D004 AA21 AB03 CA04 CA13 CA15 CA30 CA34 CA35 CA42 CB03 CB13 CC04 CC12 DA02 DA03 DA06 4D056 AB05 AB08 AC22 BA03 CA06 CA14 CA18 CA22 DA01 DA05 DA10 4G048 AA01 AB02 AB08 AC08 AE06

Claims (1)

[Claims] 1. A method for dissolving and extracting tantalum and / or niobium in a tantalum and / or niobium-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid. And / or after charging a required amount of niobium-containing alloy, first treat with caustic soda, subject the treatment liquid to solid-liquid separation, and treat the resulting insoluble product with a mineral acid other than hydrofluoric acid to obtain tantalum and niobium. Other metal impurities are eluted in the mineral acid, followed by solid-liquid separation, and the remaining insoluble product obtained is dissolved and extracted with hydrofluoric acid or a mixed acid thereof and sulfuric acid. A method for dissolving and extracting tantalum and / or niobium-containing alloy.