JPH01192728A - Production of high-purity potassium fluorotantalate - Google Patents

Abstract

PURPOSE:To produce the title compound hardly containing any impurities, by successive ly carrying out six steps including steps of removing various metallic ions from a solution of a Tacontaining raw material in HF-HCl with a cation exchange resin and adsorbing the Ta component on an anion exchange resin. CONSTITUTION:A solution of a Ta-containing raw material in HF and HCl is passed through a cation exchange resin to remove various impurities, such as Fe, Mn and Ni (first step). The resultant solution is then passed through an anion exchange resin to adsorb the Ta component thereon (second step). The impurities adsorbed together with the Ta component are subsequently washed in several steps (third step). The anion exchange resin adsorbing the Ta component is then eluted with a mixed solution of NH4NO3 and NH4F to separate the top.fraction thereof (fourth step). NH3 is subse quently passed through the residual Ta eluate to regulate pH to 6.8 and precipitate tantalum oxyfluoride (fifth step). The resultant precipitates are then filtered, washed and dissolved with HF to provide a solution. NH3 is subsequently passed therethrough to coprecipitate part of the Ta. The obtained precipitates are then filtered and the resultant filtrate is reacted with acidic KNO3 to afford crystals of K2TaF7, which are filtered, washed and dried to afford the final product (sixth step).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing high-purity potassium fluorotantalate, which is used as a mental metal material used in electronic materials, particularly electrode wiring for high-density LSIs, capacitors, etc. In particular, high melting point metals such as W and Mo are almost completely removed, and radioactive elements such as U, which have a negative impact on VLSI, are reduced to a level below PPb, making it possible to implement on an industrial scale. The present invention relates to a method for producing potassium fluorotantalate.

[Conventional technology]

As MOS memory becomes more flexible, tantalum is being used as a melt-resistant material for MOS memory. Requirements are becoming increasingly large. Until now, W, Mo, and their silicides have been put into practical use, but tantalum is not suitable for wiring (conventional SiO as an IC-related capacitor).
Since it has 5 to 6 times as much fat as □ etc., it can greatly contribute to the miniaturization and improvement of the characteristics of the device.

Conventionally, high purity Ta on an industrial scale has mostly relied on solvent extraction methods, but there are limits to the purity of Ta compounds produced by this method, such as EB
However, even if the material is purified by the above-mentioned method, leakage current due to impurities is always present, so that it is not sufficient as the above-mentioned electronic material.

Under these circumstances, there are many issues that require further consideration regarding the chemical removal of contained impurities, and in particular, there is a strong demand for countermeasures for the complete chemical removal of high flux and radioactive elements. It is something that

[Problem to be solved by the invention]

The present invention has been developed with the aim of obtaining high-purity Ta compounds by almost completely removing impurities from each strain, and the purity level of the raw materials used is The objective is to provide a complete fR manufacturing method on an industrial scale that can ensure that the final product is stable and pure even when there are fluctuations in the process.

[Friendly means of solving problems]

In order to solve the above problems, the present invention is comprised of the following six steps that are performed in sequence.

(1) First, the first step is to convert the raw material containing Ta into HF-HC.
1 solution is passed through a cation exchange resin to obtain U-M, F., Co, which is less likely to generate complexes due to HF.

This removes most of the metal ions such as Zu + Cr # Ni + P b.

01) In the second step, the Ta)IF-HCt bath from which most of the metals, U, etc. have been removed is passed through an anion exchange resin to coat the resin with Tat in solution. Furthermore, the third step is a step of cleaning impurities adsorbed on the ionic resin along with Ta in a t-order stage.

First of all, the cleaning solution is Ui, which is the most typical electronic material.
Mainly to remove HF (0.1~0.5N) and I
A mixture of C2 (0,1 to IN) is used. Depending on the composition of this mixture within the above range, most of the adsorbed U can be washed away by adding a cleaning liquid with an optimal composition in which the KD (adsorption coefficient) of U is in the range of 0 to 15.

Next, the outflow of Nb, which has properties similar to Tm and contains a relatively large amount, is caused by 3N HCl and 1. A mixture with IN)IF is used. Moreover, according to this mixed solution, in addition to Nb, TI, Zr, Hf, U, Co, Cr, and AL
, St, etc. can be removed at the same time. Furthermore, 0.5N HN
The mixed solution of O3 and 1.0NHF also removes Sn, which is relatively difficult to elute, and also removes Zr*Ni.
5AJLsIL'Os Bi sW, Hf, etc. will also be maintained.

Moreover, a relatively low 111 degrees of 0.1 to 0.3 N IC2 is used mainly to generate F@1r:#r. This washing is convenient for elution of metals that do not form complexes with low-grade HCl. Fe's t'yokaCo
, Zn, Cd.

Aj, Cr, etc. are also removed from the bath at the same time.

Furthermore, various metals are eluted by EDTA. This is done by washing the anion exchange resin with H2O until the effluent volume is close to 3, and then using a 0.05M solution of EDTA with the same volume to form a chelate compound with EDTA. , Hg, Pb, Ni, etc. However, if this cleaning is not necessary, omitting this cleaning will often have no substantial effect on the desired high purity of TaO.

As mentioned above, there are several cleaning methods to remove the ash from the fine particles, but these may be changed or omitted as appropriate depending on the type 1 impurities contained in the Ta raw material. It goes without saying that other measures may be taken.

Next, NH4 is added to the ion exchange resin that has undergone such washing.
A fourth step of removing the top fraction of the eluent after passing through a mixture of NH3' and NH4F and NH3'
The fifth step in which tantalum oxyfluoride is totally precipitated by adjusting the blowing pi''l't to 6.8 and simultaneously leaving impurities in the eluent will be explained.

First, in the fourth step, the top fujikusen, which contains minute amounts of high-melting point impurities that cannot be completely removed with ion exchange resin, is separated, and in the fifth step, the remaining eluent is neutralized. The oxyfluoride of Ta is obtained by using 3M
The mixture of NH4NO3 and IM NH4F is -3 to 3
．． It is used to make 5. In this case, there is a method of using NH2Cl or the like, but since it is difficult to remove Ct even in a trace amount, it is not preferable for electronic materials, so it is better to avoid it. An important measure in this step is that the top fraction of the eluent is separated.

# Since the top fraction of syneresis is separated from Vc, the first metals such as W and Mo are removed, and TaO increases in M content, greatly increasing the sheathing effect. becomes.

The next fifth step is to precipitate tantalum gold oxyfluoride in the form of tantalum gold oxyfluoride from the eluent remaining after the top fraction has been removed. Partition to -6,8 via NH3.

This strict adjustment of - can have a remarkable effect of preventing some impurities from being mixed into the oxyfluoride precipitate.

Furthermore, in the next 6th step, the fy-JE product of mental oxyfluoride produced in the 5th step is added to P'S.
Leave it undried after washing! N
A part of T1 and cine fines are simultaneously precipitated through coprecipitation (absorption y#) through H, to increase the purity, and then filtered, and the F solution is reacted with acidic KNO to 2TaF.

Obtain the crystals. This is then filtered, washed, and dried to produce the final product.

Note that unreacted Ta remains in the eluent and mother liquor from which oxyfluoride was separated, but at the same time, Sl remains.

Since F, etc. are also dissolved, HNO is added to make it acidic, and then NH is added to make it more than 19, and T a (O
When all H)s is produced, impurities in the liquid become the Ta (OH
) completely sorbed to s. This product is advantageous because it can be reused as an eluent for the fifth root after adjusting its composition to the /Fi base due to its purity. The high purity KNO used in the final step 61 can be obtained by the following method. First, add 1 to 2% of KNO3 in an acidic state to a bath solution of KNO3 obtained by reacting KNO crystals or KOH and HNO with gold.
Add HF bath solution of Ta and neutralize with KOH bath solution to reduce -1 to 9
If this is done above, T a (OH) s is generated. Ta(
O average.

(F solution) (made hostile with NO3) is subjected to the reaction.Ta(OH)s has a strong impurity adsorption ability, so a highly pure 0# solution can be obtained. A suitable degree is about 15%.

FIG. 1 is a process diagram showing the above first to sixth steps.

〔Example〕

Hereinafter, the present invention will be explained based on Examples.

As a raw material, mental capacitor scrap containing 7 to iohm% of Mn and various impurities was used. The Mnl of this succin f can be reduced to about 100 by aqua regia treatment. When a mixture fL of HF and HCl is applied to this scrap, it reacts violently with NO6 due to the catalytic action of Mn, and a raw material HF-HC1 liquid containing Tai is produced.

Using a set of two exchange towers each filled with 501 cation exchange resin, HF for 50 kg of the above-mentioned Succin f.
-Sheath production of a solution with adjusted mixed acid composition of HC1 was performed.

Next, two exchange towers each filled with 1501 anion exchange resin are used, the first tower adsorbs Ta, and the second tower collects trace amounts of Ta remaining in the solution. Approximately 25 yu of Ta was adsorbed as a metal in the first column.

0.3N HF-0.5N HC1 mixed solution, 1. I
NHF-3NHC6 mixture, 1.0NHF-・0.
5 N HNO, mixed solution, 0.2 N HCt solution, 0
．． Impurity t-baths are removed by sequentially using various cleaning solutions of 0.05M EDTA, each in an amount of 3 to 5 times the amount of resin. An average of 100 to 150 ppm of Ta is eluted in each washing solution, and this is collected in the second column.

The T1 analysis results of the final product are shown in the table below.

〔Effect of the invention〕

The present invention is based on the above structure, and the 7 steps of the first to sixth steps are as follows.
A method for producing high purity potassium fluorotantalate in a first step, in particular, the removal of various metal ions using a cation exchange resin in the first step is a method for producing Ta t- on a medium production scale. It is the most efficient method in this case, and it is an extremely preferable process as it can compensate for the fact that the conventional means of adsorbing Ta components using only anion exchange resin was not sufficiently suitable for ensuring stable purity. In addition, in the fourth step, the top fraction of the bath solution is separated to further purify Ta from which heavy metal ions have been separated and removed, and further, oxyfluoride is precipitated. Fifth
In the process, it is possible to prevent some impurities from being mixed into the oxyfluoride precipitate* by adjusting the PTI of 6.8 to the remaining bath solution after separating the top fraction. H of ride precipitation
A number of considerations have been taken in production to further improve purity on a production scale, such as coprecipitating NH5'i into the F bath solution to remove impurities as much as possible. This method is an extremely useful invention as it results in highly pure potassium fluorotantalate having almost no impurities.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the steps of the manufacturing method according to the present invention.

Claims (1)

[Claims] 1. A first step in which a raw HF-HCl solution containing Ta is passed through a cation exchange resin to remove various impurities such as Fe, Mn, Ni, etc.; a second step in which the Ta component in the solution is adsorbed through an ion exchange resin; a third step in which impurities adsorbed on the anion resin together with the Ta component are washed in several stages; The anion exchange resin was mixed with NH_4NO_3 and NH_
A fourth step of eluating with a mixture of 4F and separating the top fraction of the eluent, and adjusting the pH to 6.8 by passing NH_3 into the remaining Ta eluent after removing the top fraction, and adding tantalum oxyfluoride. a fifth step of precipitating the tantalum oxyfluoride and leaving impurities in the eluent; and a fifth step of filtering and washing the tantalum oxyfluoride precipitate, dissolving it with HF, passing NH_3 into the solution, partially co-precipitating Ta, and then filtration. Then, the filtrate was reacted with acidic KNO_3 to form K_2Ta.
A method for producing high-purity potassium fluorotantalate, comprising a sixth step of obtaining crystals of F_7, filtering, washing, and drying the crystals to obtain a final product. 2. In the 6th step, HNO_3 is added to the mother liquor from which tantalum oxyfluoride has been filtered, and NH_3 gas is passed through it.
2. The method for producing high-purity potassium fluorotantalate according to claim 1, wherein Ta(OH)_5 is produced at H9 or higher to adsorb impurities, and the eluent is adjusted to a predetermined composition and used again in the sixth step. 3. KNO_3 used in the sixth step is KNO_3.
2. The method for producing high-purity potassium fluorotantalate according to claim 1, wherein impurities are adsorbed and removed by Ta(OH)_5 produced when the solution of fluorotantalate is added in a small amount to 3 and then made alkaline with KOH.