JP2001213626A - Process of producing tantalum hydroxide and/or niobium hydroxide suitable for reuse of raw materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process to produce tantalum hydroxide and/or niobium hydroxide efficiently recovering ammonia and fluorine as raw materials in a suitable form of reuse even at the low cost of production as before. SOLUTION: This process comprises step (A) in which ammonia is added to the raw material liquid comprising hydrofluoric acid solution containing tantalum and/or niobium to precipitate tantalum hydroxide and/or niobium hydroxide and the precipitate is filtered, and step (B) in which calcium hydroxide is added to the filtrate obtained by the above filtration, generated ammonia is recovered through aeration and calcium fluoride precipitate formed is recovered by filtration.

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 tantalum hydroxide and / or niobium hydroxide which can recover ammonia and fluorine as raw materials in a form suitable for reuse.

[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 associated with 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.

[0004] There are several methods for producing tantalum oxide and / or niobium oxide, and the hydrofluoric acid dissolution-solvent extraction method described below is common. FIG. 2 shows a general manufacturing process of tantalum oxide and niobium oxide. As shown in FIG. 2, first, ore such as tantalite,
Raw materials such as scrap of a tantalum capacitor are ground and dissolved with hydrofluoric acid, and sulfuric acid is added to adjust the concentration of the solution. Next, this adjusted solution was filtered with a filter press to make a clean solution and subjected to solvent extraction with MIBK (methyl isobutyl ketone).
Extracted by BK. At this time, impurities such as iron, manganese, and silicon contained in the raw material remain in the raffinate, thereby removing the impurities.

When the MIBK containing tantalum and niobium thus obtained is back-extracted with dilute sulfuric acid, niobium is transferred to an aqueous solution, and pure tantalum remains in MIBK. The tantalum in MIBK is purified, back-extracted with water, and transferred to an aqueous solution.
Collect and reuse BK. On the other hand, niobium in the aqueous solution is M
Extract again with IBK, extract a small amount of tantalum, and purify niobium in the aqueous solution to a pure one. MIBK at the time of niobium purification is combined with a solvent before separation of tantalum and niobium. When aqueous ammonia is added to each of the aqueous solutions of tantalum and niobium thus purified, tantalum hydroxide and niobium precipitate. Further, the precipitate of the hydroxide is filtered, dried, and finally calcined to obtain tantalum oxide and niobium oxide.

Conventionally, as shown in FIG. 3, a filtrate (ammonium fluoride solution) obtained when a precipitate of tantalum hydroxide and niobium hydroxide is separated by filtration is concentrated / crystallized by a reboiler. It was reused as ammonium fluoride crystals.

However, this ammonium fluoride crystal is only used as a surface treating agent for glass as an industrial ammonium salt (NH ₄ F.HF) by the addition of hydrofluoric acid. It is not used as a raw material. For this reason, at present, it cannot be said that the hydrofluoric acid in the raw material has been recovered in a form sufficiently suitable for reuse.

On the other hand, in the filtrate generated from the precipitation step, since oil (MIBK) is dissolved in the liquid, there is a possibility that this oil may be mixed as a foreign substance during the production (concentration) of ammonium fluoride. For this reason, prior to the concentration step, a step of removing oil from the filtrate using activated carbon or the like is separately performed, which causes a problem that the production cost increases.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and recovers ammonia and fluorine as raw materials in a form suitable for reuse while maintaining the same low production cost as in the prior art. Another object is to efficiently produce tantalum hydroxide and / or niobium hydroxide.

[0010]

That is, the present invention provides:
(A) a step of adding ammonia to a raw material solution comprising a hydrofluoric acid solution containing tantalum and / or niobium to precipitate tantalum hydroxide and / or niobium hydroxide, and filtering off the precipitate; (B) Adding calcium hydroxide to the filtrate obtained by the filtration, recovering the generated ammonia by aeration, and recovering the generated calcium fluoride precipitate by filtration. The present invention provides a method for producing tantalum hydroxide and / or niobium hydroxide suitable for recycling raw materials.

Here, in the production method of the present invention, (C) the recovered ammonia is brought into contact with a hydrofluoric acid solution containing tantalum and / or niobium to be absorbed, and the obtained solution is mixed with the raw material liquid. It is preferable that the method further comprises a step of circulating as a part or the whole.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing tantalum hydroxide and / or niobium hydroxide according to the present invention will be specifically described.

FIG. 1 shows the tantalum hydroxide and / or tantalum hydroxide of the present invention.
Or the manufacturing process of niobium hydroxide is shown. As shown in FIG. 1, the production method of the present invention comprises (A) a precipitation step of tantalum hydroxide and / or niobium hydroxide, (B) a recovery step of ammonia and calcium fluoride, and (C) ammonia And the like.

(A) Tantalum hydroxide and / or hydroxyl
Niobium hydride precipitation step In the production method of the present invention, a hydrofluoric acid solution containing tantalum and / or niobium is used as a raw material liquid.
Here, hydrofluoric acid is used when dissolving the raw ore of tantalum and / or niobium (for example, tantalite) as a fluoride, and is inevitably contained in the raw material liquid. Therefore, as the hydrofluoric acid solution containing niobium, an aqueous solution obtained by purifying a niobium-containing aqueous solution after tantalum / niobium separation by MIBK in the above-described production process based on FIG. 2 can be used.
As the hydrofluoric acid solution containing tantalum, an aqueous solution obtained by back-extracting tantalum with water from the tantalum-containing MIBK after tantalum / niobium separation in the manufacturing process based on FIG. 2 described above can be used. It should be noted that the hydrofluoric acid solution containing such tantalum and / or niobium is not limited to these, and those manufactured by various known methods can be used.

The concentration of tantalum and / or niobium in the raw material liquid (purified liquid of tantalum and / or niobium) is not particularly limited, but the higher the concentration, the more advantageous the drainage amount. Generally, the concentration of the raw material liquid is the ore (raw material) before separation.
30 to 3 because it varies depending on the composition of Ta: Nb.
It is as wide as 00 g / L. Usually, Ta and Nb in the raw material liquid are H ₂ Ta (Nb) F ₇ or Ta (Nb) F ₅
-It is present in the aqueous solution in the form of a fluoride such as 2HF, and there is another 0.2 to 5% by weight of free hydrofluoric acid that is free.

In the production method of the present invention, tantalum hydroxide and / or niobium hydroxide are precipitated by adding ammonia to the raw material liquid. This ammonia may be added in gaseous form, but may be added to an aqueous ammonia solution (NH
₄ OH). Further, ammonium bicarbonate or ammonium carbonate can be added in an aqueous solution. The concentration of the aqueous ammonia solution and the amount thereof may be appropriately determined according to the amounts of tantalum and / or niobium in the raw material liquid, and are not particularly limited.

In the production method of the present invention, the precipitate-containing solution obtained as described above is filtered, and the precipitate composed of tantalum hydroxide and / or niobium hydroxide is filtered. This filtration step can be performed according to various known methods, and is not particularly limited.

The thus obtained tantalum hydroxide and / or
Or, niobium hydroxide is generally used as an intermediate material of tantalum oxide and / or niobium, and in that case, further processing such as drying and calcination will be performed.

(B) Ammonia and calcium fluoride
In the production method of the present invention, calcium hydroxide is added to the filtrate obtained in the step (A), the generated ammonia is recovered by aeration, and the generated calcium fluoride precipitate is recovered by filtration. I do.

Calcium hydroxide is added mainly to generate ammonia in the filtrate by the following reaction and to precipitate fluorine in the filtrate as calcium fluoride. Ca (OH) ₂ + 2NH ₄ F → CaF ₂ +2
NH ₃ + 2H ₂ O calcium hydroxide may be added in the form of a solid or in the form of an aqueous solution. Further, it is preferable that the amount of calcium hydroxide to be added is a reaction equivalent to the amount of fluorine in the raw material liquid.

The ammonia thus generated is recovered by aeration. In particular, the filtrate contains oil (MIBK)
Is dissolved, but by performing this aeration treatment, the oil is also removed at the same time, so there is no need to provide a separate step of removing the oil. Therefore, the manufacturing cost can be reduced by the aeration treatment. The aeration may be performed by flowing a gas such as air into the filtrate and exposing it, and is not particularly limited. Further, a configuration may be adopted in which ammonia collected by aeration is absorbed by a liquid such as water.

On the other hand, the generated calcium fluoride precipitate is
Collected by filtration. This filtration can be performed according to various known methods. The use of the calcium fluoride thus obtained is not particularly limited, but is preferably used as a raw material of hydrofluoric acid because it can be reused when the raw ore is dissolved to obtain a tantalum / niobium liquid.

According to a preferred embodiment of the present invention, the filtrate to which calcium hydroxide has been added is heated in order to speed up the progress of the reaction and recover ammonia and calcium fluoride sufficiently and efficiently. In addition, since the solubility of ammonia in water also decreases as the temperature rises, more ammonia can be recovered. The heating temperature at this time is 70 to 1
The temperature is preferably set to 00 ° C, more preferably 80 to 90 ° C.
° C. Within such a range, there is an advantage that ammonia can be completely recovered and the N standard in wastewater can be satisfied. In addition, the time for which the temperature is maintained at the elevated temperature may be appropriately determined in consideration of the amount of ammonia to be recovered, the processing temperature, the processing efficiency, and the like, and is not particularly limited.

(C) Ammonia Circulation Step According to a preferred embodiment of the present invention, the ammonia recovered in the step (B) is brought into contact with the hydrofluoric acid solution containing tantalum and / or niobium described in (A). And the resulting solution is circulated as part or all of the raw material liquid. This makes it possible to efficiently reuse the ammonia as a raw material without waste. In addition, this contact
The absorption is preferably performed by bringing the ammonia gas and the hydrofluoric acid solution into gas-liquid contact using a scrubber or the like, but is not limited thereto.

Here, the degree of absorption of the recovered ammonia into the hydrofluoric acid solution may be determined in consideration of the overall balance of the amount of ammonia, and is not particularly limited. Therefore, the amount may be such that the hydrofluoric acid solution is neutralized, or may be such an amount that not only the neutralization but also the precipitation of hydroxide is precipitated. The hydrofluoric acid solution in which the recovered ammonia has been absorbed in this way is circulated as part or all of the raw material liquid and is subjected to the above-mentioned step (A). Since it is added, there is an advantage that the amount of ammonia newly added in the step (A) can be significantly reduced.

Although the production method of the present invention has been described in detail above, the present invention is not limited to these.
Optional steps may be added as appropriate without departing from the purpose of the present invention.

[0027]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of specific examples, but the present invention is not limited thereto.

250 mL of a niobium liquid as a raw material liquid (mixer settler-produced liquid, solvent; water, Nb concentration; 148.6)
g / L, content of F present as HF; 37.88
g), ammonia gas was added as a neutralizing agent to neutralize the niobium solution. The amount of ammonia added at this time was 21.42 g, which is an amount that does not cause precipitation of niobium hydroxide. 25 in the resulting neutralized niobium solution
A weight percent aqueous ammonia solution was added to precipitate the niobium hydroxide. The hydroxide precipitate was separated by filtration to obtain 373.9 g of niobium hydroxide as the object of the present invention.

On the other hand, the filtrate 160 obtained by the filtration
0 mL (ammonium fluoride solution, NH ₃ content; 5
(1.38 g, F content; 57.51 g), 135 g of calcium hydroxide was added. The temperature of the resulting solution was raised to 80 ° C. to generate ammonia, and at the same time, air was introduced and aerated to recover 21.42 g of the target ammonia of the present invention. Here, the recovered ammonia can be circulated and reused as ammonia gas as the above-mentioned neutralizing agent.

By filtering the solution (calcium fluoride slurry) after the ammonia was recovered in this way, the calcium fluoride precipitate was separated by filtration to recover 141 g of calcium fluoride, which was the object of the present invention.

[0031]

As described above, according to the production method of the present invention, while recovering ammonia and fluorine as raw materials in a form suitable for reuse, the production method can be carried out while reducing the production cost as in the prior art. Tantalum and / or niobium hydroxide can be produced efficiently. If the obtained ammonia is recycled as a raw material, the production cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a process for producing tantalum hydroxide and / or niobium hydroxide in the present invention.

FIG. 2 is a view showing a process for producing tantalum hydroxide and / or niobium hydroxide in a conventional method.

FIG. 3 is a diagram showing a process of circulating a filtrate after filtration in the production process of FIG. 2;

Claims (3)

[Claims] 1. A step of adding ammonia to a raw material solution comprising a hydrofluoric acid solution containing tantalum and / or niobium to precipitate tantalum hydroxide and / or niobium hydroxide, and filtering the precipitate. And (B) a step of adding calcium hydroxide to the filtrate obtained by the filtration to collect the generated ammonia by aeration and collecting the generated calcium fluoride precipitate by filtration. A method for producing tantalum hydroxide and / or niobium hydroxide suitable for reusing raw materials. 2. The method according to claim 1, wherein the filtrate is heated to 70 to 100 ° C. when recovering the ammonia. (C) a step of contacting and absorbing the recovered ammonia with a hydrofluoric acid solution containing tantalum and / or niobium, and circulating the obtained solution as part or all of the raw material liquid; The method according to claim 1, further comprising: