JPH0270029A - Manufacture of ta or nb and its manufacturing apparatus - Google Patents

Abstract

PURPOSE:To improve the productivity of Ta or Nb and to facilitate the treatment of a mixed salt at the time of reducing K2TaF7 or K2Nb7 as a starting material by reducing the inside of a vessel to a nonoxidizing atmosphere and recovering and reducing Na and K. CONSTITUTION:K2TaF7 or K2NbF7 is charged to a reducing vessel 1 from a hopper 3 together with NaCl. The inside of the vessel 1 is evacuated 8, to which Ar or the like is introduced. A heating furnace 2 is electrified and is furthermore heated by rotating a stirrer 5 when K2TaF7-NaCl is started to metl. Na or K is charged to a melting furnace 4 and is melted. The liquid Na is gradually dropped and is brought into reaction with the above melt. Unreacted liquid Na is trapped into a lower tray of a condenser 11 for the use in the next reduction. A valve 6 is opened to extract a molten mixed salt contg. Ta powder into an acceptor 7. The mixed salt is washed by boiling water to remove NaCl, NaF and KF by melting into coarse Ta powder, which is then washed by a diluted acid and is water-washed to dry. In this way, Ta or Nb can be obtd. in good yield without using alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for producing Ta or Nb.

o' Conventionally, as a method for producing Ta or Nb, for example, the method disclosed in Japanese Patent Publication No. 58-35564 has been used.

In this method, after the reduction reaction is completed, the entire container is cooled to room temperature, the product is solidified, and then taken out directly from the container.

At this time, Na or K, which is added in excess of 10 to 20% over the theoretical equivalent, remains unreacted and poses an obstacle to safe handling. For this reason, it is necessary to convert the material into a stable compound using alcohol before cleaning.

As mentioned above, the conventional method had the following drawbacks: (1) After the reduction reaction, the whole container was cooled to room temperature, which required a long cooling time, resulting in a loss in equipment operation.

(2) 10 to 20% of Na or K stabilized with alcohol is lost as it is, and alcohol and its work are required.

■ Reduction products deposited in lumps at the bottom of the container have low solubility in water, so if they remain in lumps, it takes time to dissolve.

PROBLEMS TO BE SOLVED BY THE INVENTION The present invention solves the drawback described in 1.The purpose of the present invention is to extract the product from the system in a molten state after the reduction reaction and to make it suitable for washing treatment. The purpose is to republish unreacted Na or K.

2TaF to help solve problems
In the reduction of Na or K in 7 or 2NbF7, NaCJ is usually used to lower the melting point of t, and as a reaction heat reducer and an inhibitor of alloy formation in Na-.
It is used by mixing and adding.

As an example, a method and apparatus for reducing TaF7 with Na will be described below, but similar steps can be taken in the case of K2TaF7.

First, K2TaF7 and NaCJ are mixed and charged into a reduction vessel, and after exhausting the air, an inert gas, for example Ar, is introduced at a pressure slightly higher than human pressure, and heated in a heating furnace.

K2TaF, -NaCJ dissolves at about 600℃, but 7
Heat to 00'C to dissolve completely.

There is a Na melting furnace in the upper part of the reduction vessel, and since Na is liquid, it is dripped into 2TaF, . . . -NaCJ in small amounts.

K, 1'aF7 is reduced by Na as shown in the following equation.

K2TaF, +5Na −+ Ta +2KF −
1-5NaF This reaction generates a large amount of heat of formation, and if Na is added dropwise all at once, the reaction temperature may rise rapidly by about 200°C, and this temperature change will affect the particle size of the 1a powder produced. .

Therefore, in order to make the particle size uniform to some extent, it is necessary to control the rate of dropping Na, that is, control the reaction temperature.

After the completion of lower Naa, the temperature is maintained at 800-900°C as post l+eat, iB to grow grains of Ta powder.

Conventionally, after this, it took a long time to cool down the product in the reduction container to room temperature, but in the present invention, post
After heating, the reduction product is extracted in molten form from the bottom of the container.

The reduction product may be spread out into a thin plate shape and solidified, for example, to make the subsequent cleaning process easier.
It can also be rapidly cooled and solidified in granular form in a mold.

In the conventional method, this mixed salt was deposited in lumps at the bottom of the container, so it was impossible to crush it, and it took a long time to dissolve and wash it with hot water.

On the other hand, unreacted Na (usually used in an amount of 10 to 20% more than the theoretical equivalent) is
At this time, it is trapped in the ~a condenser provided at the top of the reduction container and re-added to 2TaF, -NaCl during the next reduction and reused.

For this reason, in the past, in order to prevent unreacted Na from igniting and burning before being extracted after reduction cooling, a large amount of alcohol was always used to stabilize the salt mixture, but in the method of the present invention, the mixed salt extracted with a solution contains Na. Alcohol is not necessary as it does not contain alcohol.

As an example, 2TaF',
.

We will describe the method and equipment for Na reduction.

The equipment consists of ■ reduction container (SUS type), ■ electric furnace, ■ raw material supply hopper, ■ Na7 @ melting furnace, ■ stirrer, ■ extraction valve (SUS type), ■ product receiver, ■ exhaust and Ar introduction. It is made up of pipes.

First, 5.0 kg of 2TaF7 (reagent number 1) and 6.0 kg of NaCJ (also number 1) are dried and placed in the hopper (2) and fed to the reduction container (2) via the feeder.

Immediately exhaust from ■ and 0. When ITorr, Ar is 1. ．．
Introduce up to 0.05 kg/d. This reduction container should be subjected to an airtight test I in advance to confirm that there are no leaks.

Next, the heating furnace (2) is energized to raise its temperature, or when the temperature reaches about 200° C. as measured by the [phase] thermometer, the furnace is evacuated from (2) again to eliminate degassed gas and Ar is introduced. When K2TaF7-NaCJ starts to dissolve at about 600'C, turn on the stirrer (2) and further raise the temperature to 700°C.

In parallel with the melting of K2TaF7-NaCJ, 5.0 kg of Na was also inserted into the Na melting furnace (2) and replaced with Ar.

Since Na reacts violently with moisture, make sure that the inside of the Naf4 melting furnace is completely dry and airtight.

Since Na has a low melting point of 98°C, it is melted at about 120°C and kept warm with a mantle heater.

K, TaF, -NaC] reaches 700'C,
Open the ■ valve and gradually drip liquid Na.

Adjust so that the [phase] thermometer reading does not exceed 700-730'C by dropping. Normally 1.5Hr (56g/m
1n) It takes.

Once the Na drop is finished, raise the temperature to 900°C to 311°C.
Hold r.

As is the case during the reaction, the pressure inside the container is 1.02 kg/d.
When the pressure becomes lower, introduce Ar and be careful not to allow negative pressure. This 900°Cpost hea
During cooling, the condenser (air-cooled condenser tube) is cooled down to about 0.
Collect unreacted Na for 5 minutes. There is an overwhelming amount of Na vapor inside the container, and the boiling point of Na is 882°C, which has a large difference from the melting point, so it is easy to condense.

Until the liquid Na accumulates in the lower tray of the condenser, the next time you reduce it, pull out the plug and let it fall. Therefore, from the next time onwards, it will no longer be necessary to use Na in excess of 10 to 20% of the theoretical equivalent.

Next, the (1) extraction valve is opened and the mixed salt solution containing Ta powder is extracted to (2) the product receiver.

To do this, simply open the needle of the withdrawal valve, which is closed during reduction, by 10-15+ nm, but the area around the valve must be heated to about 800''C to prevent the mixed salt from solidifying.

After the reaction, the products fall to the level of the withdrawal valve,
Some of the product accumulates at the bottom.

The extracted mixed salt (25.5 kg) spreads in a receiver (vat) to a thickness of 10 nwn or less and solidifies immediately.

Since this mixed salt is thin, it is easily crumbled and subsequent processing is easy, and since there is no unreacted Na, it will not catch fire even without using alcohol.

Next, the Ta powder and mixed salt are leached with hot water to remove the Na powder.
C1, NaF and KF were dissolved and removed to obtain crude Ta powder.

Subsequently, it was washed with dilute acids such as HCI and HN O3 to remove impurities such as heavy metals, and after washing with water, it was vacuum dried to obtain Ta powder of 6.7 dia.

From this, the average particle diameter (F, S, S, S) and oxygen content were measured.

Although the above embodiment describes one batch, semi-continuous operation is possible in which raw materials are charged from the hopper immediately after the mixed salt is extracted and the same reduction can be repeated repeatedly.

Table 1 shows the results of the conventional method and the method of the present invention.

Table 1 Implementation results of the conventional method and the method of the present invention = 8 (1) As explained above, 2TaF7 or 2NbF7
In the reduction with Na or K, the mixed salt after the reaction is extracted from the system in a molten state and solidified, which has the following advantages.

(1) The productivity of the apparatus is significantly improved because conventional batch reduction can be repeated in a semi-continuous manner.

(2) Unreacted Na or K can be reused, making conventional alcohol unnecessary.

(3) Since the reaction product is taken out to the coagulation device outside the reduction vessel, the mixed salt can be easily washed.

(4) The recovery rate of Ta or Nb increases.

■　Reduction container ■Electric furnace ■ Raw material supply hopper ■ Na melting furnace mixer extraction valve product receiver Exhaust and Ar introduction pipe P Na valve thermometer Na condenser

Claims (3)

[Claims] (1) In the method of recovering Ta or Nb by reducing K_2TaF_7 or K_2NbF_7 with Na or K, after the reaction, the inside of the reduction vessel is kept in a non-oxidizing atmosphere so that Na or K remains as a single substance in the reduction vessel. A method for producing Ta or Nb, which comprises taking out the mixed salt from the system, recovering Na or K in the upper part of the same furnace, and using it again as a reducing agent. (2) Production of Ta or Nb, which is characterized by having a reduction device used for production of Ta or Nb, a device that can take out the solution after the reaction from the device and can be sealed, and a coagulation device in a sealed state downstream of the device. Device. (3) An apparatus for producing Ta or Nb, characterized in that unreacted Na or K after the reaction in the above production apparatus is temporarily collected in a condenser provided in a reduction vessel and allowed to flow downward as needed.