JPS62292619A - Purifying method for niobium - Google Patents

Abstract

PURPOSE:To obtain high-purity Nb by utilizing the difference of affinity between a quaternary ammonium compd. difficult-to-dissolve in water and a Ta fluorocomplex anion, an Nb fluorocomplex anion and impurities. CONSTITUTION:After dissolving a compd. contg. Nb by hydrofluoric acid and regulating the concn. of hydrofluoric acid in an acidic aq. soln. to 4 normal and under, it is brought into contact with an organic solvent difficult-dissolve in water incorporating 1.5-5 times equivalent quaternary ammonium compd. difficult-to-dissolve in water for Ta amount incorporated in the acidic aq. soln. and thereby Ta is extracted in the organic soln. and removed. Then the acidic aq. soln. is brought into contact with the organic solvent difficult-to-dissolve in water incorporating 1-2 times equivalent quaternary ammonium compd. difficult-to-dissolve in water for Nb amount incorporated in the acidic aq. soln. and thereby Nb is extracted in the organic solvent. This organic solvent incorporating Nb is brought into contact with the aq. soln. contg. hydrofluoric acid and the impurities incorporated in the organic solvent are extracted in the aq. soln.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for purifying niobium to obtain high purity niobium compounds, particularly high purity niobium pentoxide, from crude niobium or niobium compounds containing impurities.

The recent development of the electronics industry is remarkable, and functional elements based on new principles are being developed one after another. Along with this,
The raw materials used are also required to be of even higher purity. High-purity niobium and niobium pentoxide have recently attracted attention as surface acoustic wave filters, optoelectronic devices, and superconducting materials, and higher purity is desired.

For example, in the case of surface acoustic wave filters, high-purity niobium pentoxide is used to manufacture the constituent material lithium niobate single crystal. It is strongly desired to provide the following. For optical glass, optical switches, optical waveguides, and other optoelectronic materials, high-purity niobium pentoxide, which does not contain transition elements such as iron, silicon, chromium, and nickel, which cause light absorption loss, is essential for performance reasons. be.

These demands for high purity are hardly satisfied with the conventional purity of 9996 to 99.9 Excellent (2N to 8N), and 99.9%.
The demand for purity of 91-99.9999% (4N-6N) continues.

In view of the above-mentioned requirements, the object of the present invention is to provide a high-purity pentoxide suitable for use in the electronics industry and optoelectronics field, which is free from impurities and substantially free of alkali metals, silicon, aluminum, and transition elements such as iron and nickel. The purpose of the present invention is to provide a method for refining niobium to obtain niobium.

<Conventional technology> Silicon, iron, copper, aluminum, tantalum.

As a method for purifying niobium from crude niobium or niobium compounds containing impurities such as calcium, the following distillation method and RK extraction method are generally known. The distillation method is
For example, niobium or a niobium compound is mixed with carbon and chlorinated at about 600 to 800°C by passing chlorine gas, and the difference in boiling points of these chlorides is utilized (for example, German Patent No. 1017601 and German Patent No. 1056105). o
However, in this method, for example, tungsten chloride A/(boiling point: 289°C) and niobium chloride (boiling point: 249°C)
The difference in boiling point between niobium chloride and niobium chloride is only 10°C, which is small for industrial purposes, and it is difficult to control the temperature during fractional distillation. However, the solvent extraction method has the disadvantage that highly pure niobium pentoxide cannot be obtained.The solvent extraction method involves dissolving niobium or niobium compounds containing other impurities in a tank μ, for example, with hydrofluoric acid, and then Methyl ethyl ketone, cyclohexanone, methyl isobutymu
The niobium and tank y in the acidic aqueous solution are extracted into the organic solvent by contacting with an organic solvent consisting of an aliphatic ketone such as ketone to remove impurities while leaving them in the aqueous phase, and then the organic solvent containing niobium and tank Contact μ with dilute sulfuric acid
Do you have it? gi, niobium is back-extracted into an acidic aqueous solution and separated from the tank.Furthermore, the niobium in the acidic aqueous solution is brought into contact with an organic solvent consisting of an aliphatic ketone again, and some of the niobium is back-extracted along with the niobium. However, in this method, since the difference in R phase of tantalum and niobium with respect to organic solvents is small, some of the tantalum is also removed during back extraction of niobium. At the same time, tantalum is back-extracted and then brought into contact with a fresh organic solvent again to extract the tantalum into an organic solvent. However, it is not possible to completely separate and remove the tantalum, and contamination of the tank with 0.1 to several percent of niobium cannot be avoided. 0 Also, when extracting tank μ and niobium into an organic solvent,
A small amount of impurities that were extracted along with the niobium were back-extracted into an acidic aqueous solution together with the niobium during the niobium back-extraction, and could not be separated from the niobium, resulting in a disadvantage that highly pure niobium pentoxide could not be obtained.

<Problems to be Solved by the Invention> The problems to be solved by the present invention are that, under the current circumstances, it is possible to efficiently produce tanta, alkali metals, silicon,
The problem is solved by providing a method for producing niobium w4 that can remove aluminum, transition elements, etc. and obtain a high-purity niobium compound, especially high-purity niobium pentoxide, which is substantially free of them. Means for Purifying Niobium> The present inventors have developed a method for purifying niobium with high purity, high yield, and economical excellence from niobium or niobium compounds containing impurities. The contained compound is dissolved with hydrofluoric acid or an acid containing hydrofluoric acid, and then, after adjusting the hydrofluoric acid concentration, it is mixed with a poorly water-soluble organic solvent containing an equivalent or more of a poorly water-soluble 4M ammonium compound. When brought into contact, tantalum is extracted and removed into the organic solution with extremely high selectivity, and when the acidic aqueous solution containing niobium after removing the tank μ is mixed and brought into contact with the organic solution, niobium is efficiently removed. organic g
The affinity between niobium and the 4R ammonium compound in the organic solution is compared to the affinity between the 4R ammonium compound and other impurities that are partially extracted along with niobium. By contacting the organic solution containing niobium, which is much stronger, with an aqueous wash solution containing a compound selected from the group consisting of hydrofluoric acid inorganic acids and ammonium salts, most of the niobium in the organic solution is removed from the aqueous wash solution. It was discovered that the impurities in the organic solution were almost completely removed by washing into the washing aqueous solution, while the impurities in the organic solution were almost completely removed by washing into the washing water. After dissolving with an inorganic acid containing niobium or hydrofluoric acid, and then reducing the hydrogen fluoride concentration of the obtained acidic aqueous solution containing niobium to 4N or less, the acidic aqueous solution and the acidic aqueous solution containing niobium are dissolved. Tantalum is selectively dissolved in an organic solution by mixing and contacting a poorly water-soluble organic solvent containing a poorly water-soluble quaternary ammonium compound in an amount of 1.5 to 5.0 times the amount of a small amount of impurities in the tank μ. The process of extraction and removal.

(b) An acidic aqueous solution containing niobium after extracting and removing the tank ρ, and a poorly water-soluble quaternary ammonium compound in an amount of 1.0 to 2.0 times the equivalent of the amount of niobium contained in the acidic aqueous solution. The niobium-containing organic solution obtained in the step (/1 (t=)) of extracting the niobium in the acidic aqueous solution by mixing and contacting the slightly water-soluble organic solvent containing the organic solution with hydrofluoric acid. , an aqueous solution containing at least hydrofluoric acid selected from the group consisting of inorganic acids and ammonium salts, and removing impurities extracted along with niobium in the organic solution. The present invention relates to a method for purifying niobium characterized by the following.

The method of purifying niobium using a water-repelling tg quaternary ammonium compound as in the present invention was completely unknown in the past, and for the first time in the method of the present invention.
It has become possible to industrially obtain niobium pentoxide with a high purity of 9% to 99.9999% (5N to 6N).

The present invention will be specifically explained below. The niobium-containing crude raw materials used in the present invention include crude niobium pentoxide, niobium hydroxide, niobium compounds such as niobate, single crystal waste such as lithium niobate, etc. Opmetal y-containing scraps and mixtures thereof are preferred.

First, these crude raw materials are dissolved in hydrogen fluoride or a mixed acid containing hydrofluoric acid and, if necessary, an inorganic acid such as hydrochloric acid, nitric acid, or sulfuric acid. Next, using water, the concentration of hydrofluoric acid in this acidic aqueous solution containing niobium is adjusted to 4N, preferably 2N.
It is known that each impurity element present in niobium or crude raw materials exists in different states depending on the element in such an acidic aqueous solution. i.e. alkali metals such as lithium, sodium, potassium, lithium,
alkaline earth metals such as magnesium,
Elements such as manganese, iron, nickel, and copper are used as cations, while elements such as aluminum, titanium, silicon, and tin are partially used as fluoride anions. ?)% Niobium exists in the form of fluorocycles such as pentafluoroquiniopic acid (H-Nbopg).

The present invention is based on the difference in the affinity between the various elements and the quaternary ammonium compound based on the existence form of the above various elements in an acidic aqueous solution and the shape of the fluorine complex of niobium and tantalum.
〇 Tantalum is one of the impurities that must be removed to purify niobium, and is the most difficult element to separate. Focusing on this, tantalum is extracted and removed using an acidic aqueous solution containing niobium or an organic solution containing a hardly water-soluble quaternary ammonium compound.

The poorly water-soluble quaternary ammonium compound used in the present invention is represented by the following general formula (where RX, R,
R,, R4 represents an alkyl group or an aralkyl group, R
The total number of carbon atoms from 1 to R4 is 20 to 80, x
H represents halogen, hydroxyl group, nitric acid group, carbonic acid group or sulfuric acid group, and n represents 1 or 2. ) Due to the presence of non-polar hydrocarbon groups, it is soluble in organic solvents, but poorly soluble in water or acidic or alkaline aqueous solutions (
(including insoluble). Specific examples of poorly water-soluble quaternary ammonium compounds include tri-n-octylmethylammonium chloride, tetra-n-hexyl-ammonium iodide, cetylbenzyldimethylammonium chloride, n-octylmethylammonium hydroxide, and bistetra-n sulfate. Examples include -hexylammonium, tri-n-octyl-methylammonium nitrate, and bistri-n-octyl-methylammonium carbonate.

The poorly water-soluble organic solvent for dissolving the poorly water-soluble quaternary N & ammonium compound is a low polar organic solvent that is soluble in water and phase separates from water, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, hexane, heptane,
Aliphatic hydrocarbons such as cyclohexane and kerosene, alcohols such as isoamyl alcohol, octatool, and tridecyl alcohol, ketones such as methoxyketone and methyl isobutyl ketone, halogenated hydrogen dihydrides such as chloroform and dichloroethane, and ethyl ether, propi〃
Examples include ether lvs such as ether, and mixtures thereof.

The amount of the poorly water-soluble quaternary ammonium compound contained in the poorly water-soluble organic solvent is preferably 1.5 to 5.0 times equivalent to the impurity tanta/V in the acidic aqueous solution containing niobium. Adjust to 1.5 to 2.0 times equivalent.

If the amount of quaternary ammonium compound in the organic solution is less than the equivalent amount to the tank containing the acidic aqueous solution, tantalum in the acidic aqueous solution will not be completely extracted and removed, tantalum will remain in the acidic aqueous solution, and niobium will be extracted. Sometimes it is extracted together with niobium and cannot be removed by subsequent washing, making it impossible to obtain highly pure niobium. On the other hand, for tantalum in acidic aqueous solution, 6.
When using a quaternary ammonium compound that exceeds 0 times equivalent, the removal of tank y in the acidic aqueous solution becomes more complete, but an excess of quaternary ammonium compound that is more than equivalent to tank ~ is used for extraction of niobium. , the amount of niobium extracted and removed along with tantalum increases, resulting in a loss of niobium, which is undesirable.

In addition, when the hydrofluoric acid concentration in the acidic aqueous solution is 4N or more, the affinity between the tantalum fluorine complex anion and the quaternary ammonium compound and the affinity between the niobium fluorine complex anion and the *4fi ammonium compound This is not preferable because the difference in tantalum becomes smaller, the tantalum selectivity during tantalum extraction decreases, and the separation between the tank and niobium deteriorates.

The mixed contact between the acidic aqueous solution containing niobium and a small amount of tantalum and the organic solution containing the water-soluble quaternary ammonium compound can be carried out using known fluid contact means, such as a batch-type mixing extraction device, a mixer setoff type liquid-liquid This can be carried out using an extraction device, a vertically moving liquid-liquid countercurrent extraction device, or the like.

Through this mixed contact, the impurity tantalum in the acidic aqueous solution is almost completely extracted into the lc organic solution, and when the organic solution is removed in layers, an acidic aqueous solution containing only niobium and substantially no tank y is obtained. An acidic aqueous solution containing niobium that does not contain tantalum and a water-soluble organic solvent containing a water-soluble quaternary ammonium compound are mixed and contacted to extract niobium in the acidic aqueous solution into an organic solution. The amount of poorly water-soluble quaternary ammonium compound contained is 1.0 to 1.0 to niobium contained in the acidic aqueous solution.
The amount is selected to be 2.0 times equivalent, preferably 1.0 to 1.5 times equivalent. If the amount of the quaternary ammonium compound in the organic solution is less than the equivalent amount to niobium, niobium in the acidic aqueous solution cannot be completely extracted, resulting in a decrease in the yield of niobium. Even if the amount of the quaternary ammonium compound in the organic solution exceeds 2.0 equivalents to niobium, no particular improvement in the extraction rate of niobium is observed.

Mixing and contacting of the two liquids can be carried out using the liquid contacting means described above. By this mixing and contacting, almost all of the niobium in the acidic aqueous solution is extracted into the organic solution, and only a small amount of impurities other than niobium are extracted with the niobium. By mixing and contacting the thus obtained organic solution containing substantially only niobium, which remains in the acidic aqueous solution after being extracted, with the cleaning aqueous solution using the liquid contacting means described above, a part of the niobium is removed. , the impurities extracted into the organic solution along with the niobium are washed away.

The aqueous solution for cleaning the organic solution is an aqueous solution containing at least hydrofluoric acid selected from the group consisting of hydrofluoric acid, inorganic acids, and ammonium salts, and specifically, an aqueous solution of hydrofluoric acid alone or hydrochloric acid, Examples include an aqueous solution containing hydrofluoric acid and at least one compound selected from the group consisting of inorganic acids such as nitric acid and sulfuric acid, and ammonium salts such as ammonium fluoride, ammonium chloride, ammonium nitrate, and ammonium sulfate. Preferably, an aqueous solution consisting of hydrofluoric acid and the above-mentioned inorganic acid or ammonium salt is used, and in particular, a mixed acid aqueous solution of hydrofluoric acid and hydrochloric acid or hydrofluoric acid and sulfuric acid can be suitably used.

The concentration of hydrofluoric acid contained in the cleaning aqueous solution is 0.5 mo
1/) or more, more preferably 1 mol/7 or more. If it is less than 0.5 mol/J, niobium flows out into the washing aqueous solution during washing, resulting in a large decrease in the yield of niobium.

The concentration of inorganic acids other than hydrofluoric acid and ammonium salts contained in the cleaning aqueous solution is 4 mol/J or less as a sum, more preferably 2 mol/7 or less.
If the ratio is mol/1 or more, niobium flows out into the washing aqueous solution, resulting in a large decrease in the yield of niobium.

The organic solution containing only niobium obtained as described above is brought into contact with an aqueous solution containing aqueous ammonia in a conventional manner to hydrolyze the niobium fluorine complex, and the produced niobium hydroxide is precipitated and separated. About 900 pieces of dried Tsuki
High purity niobium pentoxide can be obtained by calcining and dehydrating at ℃ 0 According to the method of the present invention, the yield is 95%, and the content of impurities in tank y is 10 ppm or less, alkali metals, iron. High purity niobium pentoxide containing impurities such as manganese, silicon, aluminum, and other transition elements of several ppm or less can be obtained.

On the other hand, an organic solution containing a quaternary ammonium compound from which niobium has been extracted is obtained by hydrolyzing and separating niobium and then treating it as it is or with an aqueous acid solution such as hydrochloric acid to separate the oil and liquid, resulting in almost no loss as an organic solution. It can be recycled and used again without needing to be used.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 As a raw material, niobium 57.411. Tantalum 4.2*.

Silicon 1.5*, iron 0.4%, titanium 0.2*, tin 0
, 1 * Crude niobium hydroxide 1 containing sodium, potassium, and aluminum (all of which are heavy and heavy)
57.15', dissolved with hydrofluoric acid and diluted with dissolved water, 45.1 f/I for niobium and 8.1 f/I for tantalum.
8ri/j 2jp of an acidic aqueous solution with a hydrofluoric acid concentration of 0.5N! 90 Trichloride as a poorly water-soluble quaternary ammonium compound
Using toluene as a poorly water-soluble organic solvent, a toluene solution containing 29.5 f/J of trin-octylmethylammonium chloride was prepared by IJ.
The above niobium-containing acidic aqueous solution 2 and the quaternary ammonium compound-containing toene solution 1j were put into the prepared extraction tank with a stirrer of 〇Contents@51, and the liquid was stirred for about 1 hour, allowed to stand still and separated, and the tantalum was extracted. The tank in the acidic aqueous solution containing the remaining niobium extracted and removed by the organic solution was virtually undetectable.

Then, 28% of tri-n-octylmethylammonium chloride
5.5? Prepare a toluene solution containing /I and add it to the above acidic aqueous solution containing substantially no tank y,
Similarly, the niobium in the acidic aqueous solution was stirred and mixed for about 1 hour, and then separated by standing to extract it into an organic solution. The organic solution from which niobium was extracted as described above and 2 J of mixed acid with a hydrochloric acid concentration of 1N and a hydrofluoric acid concentration of 2N.
The niobium was brought into mixed contact with the niobium, and some of the inert substances extracted along with the niobium were washed away with an acidic aqueous solution.

This washing operation was repeated twice in total, and after removing the inert substances in the organic solution, ammonia water was added to the washed niobium-containing organic solution until the pH became 8 to 9, and the niobium was hydrolyzed. It was precipitated and separated as niobium oxide.

This precipitate was filtered, washed with pure water, dried, and then calcined at 900° C. for 4 hours to obtain purified niobium pentoxide. The yield and impurity content of the obtained niobium pentoxide were as shown in Table 1.

Table 1 □□□□Be) Example 2 As raw materials, 161.9g6 of niobium, 4.5% of 'J thium
, tantalum i, o96, silicon 0.8 m, potassium 1
．． Using single crystal scrap 116.62 containing niobium 1% and aluminum 0.1% (both weight %), it was dissolved in a mixed acid of hydrofluoric acid and sulfuric acid, and the undissolved portion was diluted with filtered pure water to obtain niobium 86.62. 1/1, 2J of an acidic aqueous solution containing 0.4N of hydrofluoric acid and 1N of K acid was prepared.

Slightly water-soluble quaternary ammonium compound (hydroxide) n-octylmethylammonium, sparingly water-soluble @ using xylene as a solvent, containing tri-n-octylmethylammonium hydroxide 19.91/1 Add 1 xylene solution
4 adjustments were made.

Acidic aqueous solution 21 containing the above niobium and organic solution 1 containing a quaternary ammonium compound! were placed in an extraction tank with an internal volume of 51 mm and equipped with a stirrer, and the two liquids were stirred and mixed for about 1 hour.
The mixture was allowed to stand still for separation, and the tank μ was extracted and removed into an organic solution.

No tantalum was detected in the remaining acidic aqueous solution.

Next, a coconut solution tα2.5j containing 120 f/J of tri-n-octylmethylammonium hydroxide was prepared, added to the above acidic aqueous solution, and stirred and mixed to extract niobium in the acidic aqueous solution into an organic solution. Tangent f8 liquid 2 from which niobium was extracted by K.
2N and fluoride water x acidity, ammonium nitrate degree 0.
The impurities that were partially accompanied by the niobium and extracted were removed by washing with the acidic aqueous solution. This operation was repeated 8 times in total to remove the impurities in the organic solution. 97 below 0 removed! Purification was carried out in the same manner as in Example 1. Niobium pentoxide was obtained. The yield and impurity content of niobium pentoxide were as shown in Table 2. It has the effects described below.

Claims (3)

[Claims] (1) (a) A compound containing niobium is dissolved in hydrofluoric acid or an inorganic acid containing hydrofluoric acid, and then the concentration of hydrofluoric acid in the acidic aqueous solution is reduced to 4N or less, and then the compound containing niobium is dissolved in the acidic aqueous solution. The tantalum in the acidic aqueous solution is mixed and contacted with a poorly water-soluble organic solvent containing a poorly water-soluble quaternary ammonium compound in an amount of 1.5 to 5.0 times the amount of tantalum contained in the acidic aqueous solution. Step of extracting and removing tantalum in an organic solution (b) An acidic aqueous solution containing niobium after tantalum has been removed and 1.
The product obtained in step (c) and step (b) of extracting niobium in the acidic aqueous solution with the organic solution by mixing and contacting with a poorly water-soluble organic solvent containing a water-repellent quaternary ammonium compound in an amount of 0 to 2.0 times equivalent. The niobium-containing organic solution is brought into contact with an aqueous solution containing at least hydrofluoric acid selected from the group consisting of hydrofluoric acid, inorganic acids, and ammonium salts, and niobium and niobium are added to the organic solution. 1. A method for purifying niobium, comprising the step of removing impurities incidentally extracted. (2) A method for purifying niobium according to claim 1, characterized in that a quaternary ammonium compound represented by the following general formula is used as the poorly water-soluble quaternary ammonium compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Here, R_1, R_2, R_3, and R_4 represent an alkyl group or an aralkyl group, and R_1 to R_4
The total number of carbon atoms is 20 to 80, X represents a halogen, a hydroxyl group, a nitric acid group, a carbonic acid group, or a sulfuric acid group, and n represents 1 or 2. ) (3) The aqueous solution containing at least hydrofluoric acid selected from the group consisting of hydrofluoric acid, inorganic acids, and ammonium salts is selected from hydrochloric acid, nitric acid, sulfuric acid, ammonium fluoride, ammonium chloride, ammonium nitrate, and ammonium sulfate. 2. The method for purifying niobium according to claim 1, wherein the method is an aqueous solution containing at least one compound and hydrofluoric acid.