JPH0610074A - Method for isolating tantalum and niobium - Google Patents

Abstract

PURPOSE: To make it possible to economically isolate tantalum from a starting raw material which is extremely little in the content of tantalum and is rich in niobium by a chemical treatment of a wet process and solvent extraction without using an indirect melt metallurgical method which is heretofore necessary.

CONSTITUTION: This wet process metallurgical method for isolating the tantalum and the niobium consists in treating the raw material contg. the tantalum and the niobium with hydrofluoric acid alone or a mixture composed of the hydrofluoric acid and sulfuric acid, then solvent extracting the fluorocomplex of the tantalum and the niobium by using methyl isobutyl ketone(MIBK) from the treated soln. and subjecting the org. ketone phase contg. the tantalum and the niobium to steam distillation, thereby newly producing the water phase capable of selectively extracting the tantalum by coming into contact with the fresh MIBK.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

FIELD AND BACKGROUND OF THE INVENTION The present invention is directed to treating raw materials containing tantalum and niobium with hydrofluoric acid alone or with a mixture of hydrofluoric acid and sulfuric acid, followed by the use of methyl isobutyl ketone from the treatment solution. The present invention relates to a hydrometallurgical method for isolating tantalum and niobium by solvent extraction of a fluorocomplex of tantalum and niobium, and then steam distillation of an organic ketone phase containing tantalum and niobium.

Tantalum and niobium are co-produced in most natural resources. However, the quantitative ratio of these two kinds of elements characteristically differs depending on the ore and the underground deposit. Niobium is generally obtained from Columbite and / or pyrochlore ores from Brazil, Canada and elsewhere. These ores, however, contain a small amount of tantalum. Ore rich in tantalum, such as tantalum, contains a correspondingly small amount of niobium.

However, for the isolation of tantalum and niobium, slag, which is mainly produced in the isolation of tin, is also used (Thailand, Brazil). Although these tin slags contain only small amounts of niobium and tantalum, they are now regarded as the most important source of these two elements.
Also, in these tin slags, the Ta / Nb ratio changes greatly.

Usually, these two types of metals or their compounds are
From the raw materials containing a very small amount of tantalum and niobium, for example, tin slag, the melt-metallurgical concentration method (fu
Indirectly isolated by sion metallurgical enrichment methods. Only tantalum / niobium concentrates obtained by artificially enriching in this way can be used economically in wet chemical processes. Currently, among these tin slags, tantalum is a very inconvenient T, as if it were a natural Kolumbu stone.
Some contain a / Nb ratio, that is, a small amount of tantalum and abundant niobium. Conventionally performed hydrometallurgical treatments and separation methods require a Ta / Nb ratio in the concentrate of at least 1: 3 and are therefore not applicable to these slags for economic reasons.

A conventional hydrometallurgical method for isolating tantalum or niobium is disclosed in US Pat. No. 3,117,833,
This consists of treating the tantalum / niobium raw material in a mineral acid, preferably a hydrofluoric acid / sulfuric acid mixture. Thereby both tantalum and niobium are dissolved as fluorocomplexes and subsequently methyl isobutyl ketone (MIB
K, 2-methyl-pentan-4-one) is used to separate first from the entrained elements and then from each other by multi-step solvent extraction. Here, the fluoroniobates or fluorotantalates are sequentially selectively re-extracted and further processed to give pure tantalum or niobium compounds.

Specifically, this shows that niobium can be selectively removed from the organic ketone phase containing niobium and tantalum, for example with dilute sulfuric acid, while the tantalum remaining in the organic phase can be reextracted with water.

However, using raw materials rich in niobium and having very low tantalum content, tantalum is present in the organic ketone phase only at very low concentrations at this point. This means that the volume / time yield becomes extremely poor and cannot be an economical method.

Further, US Pat. No. 3,403,983 discloses a fluorocomplex of these metals from a solution of the fluorocomplex of niobium and tantalum in an organic solvent which is easily steam distilled and is substantially immiscible with water. In the method of producing an aqueous solution of, the fluoro complex in the organic solvent obtained by extracting from the ore by a known multi-stage extraction method is subjected to steam distillation, and the solvent is quantitatively (completely) evaporated, Disclosed is a production method characterized in that a non-distillable aqueous solution containing a fluoro complex at a concentration higher than the content is obtained.

As a result, the problem of emulsion formation can be avoided, the organic solvent can be easily recovered and recycled, and an aqueous solution of niobium / tantalum fluoro complex having a concentration 3 to 4 times higher than that in the organic solvent solution can be obtained. The aqueous solution thus obtained is very suitable for economically carrying out the crystallization of K ₂ TaF ₇ .

The method therefore does not apply especially to niobium / tantalum complexes with a very low tantalum content.

The main object of the present invention is to provide a method which overcomes the above mentioned prior art and solves the above mentioned problems.
In particular, the method uses a starting material with a very low tantalum content and a high niobium content at the same time, by wet chemical treatment and solvent extraction, without using the indirect melting metallurgy method that was necessary in the conventional method. Suitable for isolating tantalum economically. Furthermore, all niobium is also isolated.

SUMMARY In accordance with the present invention, these problems are addressed when raw materials containing tantalum and niobium, such as tin slag, niobium ores and / or concentrates thereof, are treated with hydrofluoric acid alone or hydrofluoric acid and sulfuric acid. Treated with the mixture, and the resulting acid solution is initially MIBK
It is solved by extraction with (methyl isobutyl ketone), thereby transferring the niobium and tantalum together into the organic phase. Usually, the total amount of transition metals is calculated as oxides, and combined oxides (“CO”)
And abbreviated). Normally, niobium has not been selectively re-extracted from the organic phase so far with mineral acids or water, but the CO-containing ketone phase is subjected to steam distillation. This means that both valuable substances are converted to the aqueous phase in a highly concentrated form. Tantalum is now selectively extracted from this aqueous phase using fresh ketone (MIBK), while niobium remains in the aqueous phase.

The present invention thus treats a raw material containing tantalum and niobium in the aqueous phase with hydrofluoric acid alone or with a mixture of hydrofluoric acid and sulfuric acid, followed by the use of methyl isobutyl ketone from the resulting aqueous solution. In a hydrometallurgical process for isolating tantalum and niobium, which is then subjected to solvent extraction of a fluorocomplex of tantalum and niobium, and then steam distillation of an organic ketone phase containing tantalum and niobium to newly generate an aqueous phase. From the fresh aqueous phase thus produced, tantalum is selectively extracted with fresh methyl isobutyl ketone, while leaving substantially all of the niobium in the same aqueous phase.

By choosing the ratio of organic phase to aqueous phase, the amount of tantalum in the newly formed MIBK phase can be adjusted to the desired concentration. When this organic phase is subjected to further steam distillation, the concentration of tantalum in the aqueous phase newly formed by the distillation increases. A preferred embodiment of the present invention consists of treating the newly formed organic ketone phase containing tantalum with steam, thereby reextracting the tantalum.
The new concentrated tantalum solution thus produced can be processed further in a known manner.

The method of the present invention is excellent in that it can be applied to various raw materials having various tantalum / niobium content ratios. It is particularly advantageous when the Ta: Nb ratio in the raw material containing tantalum and niobium is 0.2 or less. The method is preferably applicable to columbite and / or tin slag with a Ta: Nb ratio of 1: 5 to 1:15.

Detailed Description of the Preferred Embodiments The invention is explained in more detail below by means of examples. However, the present invention is not limited to these examples.

[0017]

EXAMPLE 35% by weight Nb ₂ O ₅ , 4% by weight Ta ₂ O ₅
And a columbite ore containing SiO ₂ , FeO, MnO ₂ , TiO ₂ , and other impurities at a concentration of 70%.
Was treated with hydrofluoric acid alone. This makes CO (=
A solution with a total oxide of 135 g / l Nb ₂ O ₅ + Ta ₂ O ₅ ) and an acidity of 20 N was obtained. Ta of this raw material solution:
The Nb ratio was about 1: 9, corresponding to that of the raw ore.
The resulting solution was passed countercurrently through an organic phase consisting of methyl isobutyl ketone (MIBK) in a solvent extractor. The target valuable substance was sufficiently extracted from the raffinate (extraction residual liquid), and the CO was 0.3 g / l.
The ketone phase containing 89 g / l CO was washed with a small amount of 12N sulfuric acid to remove other elements extracted at the same time. The ketone phase containing niobium and tantalum was placed in the apparatus and subjected to steam distillation. TaNbMIBK solution 13 per hour
0 l was continuously fed to the top of the distillation column, while steam was fed to the bottom of the distillation column at 50 l per hour. All MIBK was distilled off leaving 30-40 liters of niobium and tantalum concentrate. These elements are
20 g / l Ta ₂ O ₅ and 180 g / l Nb ₂ O ₅ (ie
It was present as a fluoro complex at a concentration ratio of Ta: Nb = 1: 9). Since the acidity of the water phase of this steam distillation method is relatively low, selective extraction of tantalum was carried out using the same aqueous solution as it was.
It was carried out by contacting with new MIBK at a rate of 1 / h at a rate of 5 l / h, while niobium (180 g / l Nb ₂ O ₅ )
Remained in the aqueous phase and was treated separately. The obtained organic phase containing tantalum (140 g / l Ta ₂ O ₅ ) was added once again,
Treatment with steam (3 l TaMIBK solution / 1 l steam ratio) removed all MIBK from the system to produce a concentrated aqueous solution of tantalum fluoride (Ta ₂ O ₅ equivalent 200 g /
l or more). The tantalum fluoride obtained is obtained from US Pat.
KCl was added and converted to the final product, potassium heptafluorotantalate, in the usual manner as described in the Examples of 51,547.

Comparative Example (US Pat. No. 3,117,833
Niobium / processed ore used in Example 1
The tantalum solution was placed in a solvent extraction apparatus in the same manner as in Example 1,
It was passed countercurrently through an organic phase consisting of methyl isobutyl ketone (MIBK). The ketone phase contained 90 g / l C.O. and was washed with a small amount of 12N sulfuric acid to remove other extracted elemental impurities at the same time. Niobium is
The ketone phase containing niobium and tantalum was treated with 2N sulfuric acid to selectively and completely convert it into an aqueous phase, which was used as a niobium fluoride fluoride solution to isolate niobium hydroxide.
The ketone phase containing only tantalum as Ta ₂ O _{5 at} a concentration of 7.5 g / l was removed by steam distillation to convert it to an aqueous phase containing 25 g / l or less of Ta ₂ O ₅ . This solution has a relatively low tantalum content and requires a large amount of heat energy to be vaporized, and an attempt to produce tantalum hydroxide results in a very large amount of salt-containing wastewater, which cannot be further processed. Not economically appropriate.

The main features and aspects of the present invention are as follows.

1. A raw material containing tantalum and niobium is treated in the aqueous phase with hydrofluoric acid alone or with a mixture of hydrofluoric acid and sulfuric acid, and then a) using the methyl isobutyl ketone from the same aqueous solution, the fluorofluoric acid of tantalum and niobium Solvent extraction of the complex and then b) in a hydrometallurgical process for isolating tantalum and niobium which steam-distills the organic ketone phase containing tantalum and niobium to give rise to an aqueous phase, c) thus occurring A method for isolation, characterized in that tantalum is selectively extracted from the fresh aqueous phase with fresh methyl isobutyl ketone, while substantially all the niobium remains in the aqueous phase.

2. A method according to claim 1, wherein the new organic ketone phase containing tantalum is treated with steam again to re-extract tantalum.

3. In the second term, the Ta / Nb ratio is
Isolation method characterized in that ≦ 0.2 in a precursor containing tantalum and niobium.

4. In the first term, the Ta / Nb ratio is
Isolation method characterized in that ≦ 0.2 in a precursor containing tantalum and niobium.

5. The isolation method according to the above item 1, wherein the distilled ketone phase is condensed and reused in steps (a) and / or (c).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Joachim Etzkert Germany Day 3388 Bad Harzbruck 1 Bismarck Schutlerse 25 Ar (72) Inventor Walther Brutussus Germany Day 3387 Feinenburg 6 Ostschutler SE 14

Claims (1)

[Claims] 1. A raw material containing tantalum and niobium is treated in the aqueous phase with hydrofluoric acid alone or a mixture of hydrofluoric acid and sulfuric acid, and then a) tantalum from the same aqueous solution using methyl isobutyl ketone. In a hydrometallurgical process for isolating tantalum and niobium, which is subjected to solvent extraction of a fluorocomplex of niobium with niobium, and then b) steam distillation of an organic ketone phase containing tantalum and niobium to newly generate an aqueous phase, c). An isolation method, characterized in that tantalum is selectively extracted from fresh water phase thus produced with fresh methyl isobutyl ketone, while substantially all of niobium is left in the same water phase.