JPS5915967B2 - Method for reducing zirconium tetrachloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for obtaining spongy metallic zirconium by reducing zirconium tetrachloride vapor with molten metallic magnesium.

When performing a reduction reaction of zirconium tetrachloride with magnesium, conventionally, an apparatus as shown in FIGS. 3, or a method in which zirconium tetrachloride vapor is further introduced through a guide pipe 4 or the like has been adopted.

In this case, both reactions mainly proceed on the surface of the molten magnesium, but the formation of metallic zirconium 5 is also observed on the inner wall surface of the upper part of the crucible 2 due to the reaction between magnesium droplets and vapor and zirconium tetrachloride vapor.

Such a reaction on the inner wall surface is unavoidable in an apparatus in which zirconium tetrachloride vapor is introduced onto molten magnesium, as in the apparatus shown in both figures, so such a reaction has a poor yield, and as will be explained later. The zirconium that formed on the inner walls was of low quality, and even if it was recovered, it would not be usable as a reactor material.

Furthermore, the method for producing metallic zirconium previously proposed by the present inventor in Japanese Patent Publication No. 56-8901 involves reducing the vapor of zirconium tetrachloride with molten metallic magnesium in the same manner as above.

At this time, after the reduction reaction, the crucible is taken out and the lower part of the crucible that holds a large amount of produced zirconium is separated, and the lower parts of the multiple crucibles are collected and charged into one vacuum distillation apparatus to remove the by-product magnesium chloride and unreacted metal. Separate magnesium from zirconium.

On the other hand, most of the magnesium chloride retained in the upper part of the crucible, which had been separated, was extruded out using a press, and the mixture of zirconium, magnesium chloride, etc. that had adhered to the inner wall surface was removed. After being removed, it is reused by joining it to the lower part of the crucible.

Since such deposits are firmly attached to the wall surface, it is difficult to remove them mechanically. Conventionally, the deposits are immersed in water to elute the magnesium chloride content in the deposits and to absorb the heat of dissolution. A small gap was created between the deposit and the wall surface, and a chisel was inserted into the gap to remove it.

The zirconium recovered in this way naturally adsorbs a large amount of moisture, and some of it is converted into oxides due to heat generation, so it can no longer be used for nuclear reactors, and can only be used as a raw material for low-quality metals. Even in this method, the yield was still low, as in some cases it was discarded.

In the process of reducing zirconium tetrachloride vapor with molten magnesium metal as described above, the present inventors believe that if the upper part of the crucible is joined to the lower part with sponge-like zirconium etc. attached to the inner wall surface and the reused unit is used, the reduction reaction can occur. Due to the high temperature at the time, the adhesion of the deposits to the wall weakens, and when the amount of deposits increases to a certain extent, it falls to the bottom of the crucible and is made into a product, so there is always only a constant amount of deposits on the wall. I discovered that it doesn't exist.

Based on the above findings, the present invention removes most of the by-product reducing agent metal chloride in advance, so that the spongy metal remains on the wall surface together with a small amount of by-product metal chloride and unreacted reducing agent metal. The upper part of the crucible is joined and integrated with the lower part of the empty crucible, and the reduction reaction is carried out again inside the crucible.

The gist of the present invention is to take out the crucible from which spongy zirconium can be precipitated from a reduction reaction apparatus for producing spongy zirconium by heating zirconium tetrachloride with metallic magnesium, and to cut it. A lower part of the crucible that can hold a relatively large amount of zirconium,
In this method, most of the magnesium chloride from the upper part of the crucible is divided into the upper part of the crucible that can hold a relatively small amount of zirconium, while removing most of the by-product magnesium chloride present in the crucible and separating and recovering the spongy zirconium. After removing the zirconium, a relatively small amount of zirconium supported on the inner wall of the upper part of the crucible is kept in a dry state, and the upper part of the crucible is joined and integrated with the empty lower part of the crucible for reuse. It consists in a method for reducing zirconium.

The reducing device used to carry out the method of the present invention may be configured as shown in FIGS. 1 and 2, or in the device shown in FIG. In addition to this, various known reduction devices may be used.

At this time, especially when the by-product magnesium chloride 6 coexists with zirconium 5 in the upper part of the crucible 2 as shown in Fig. 2, the crucible 2 is taken out from the furnace 1 and cut as shown in A-A. Cut at a position where most of the produced zirconium is contained at the bottom of the crucible.

The magnesium chloride on the top of the crucible is removed using a press or other conventional mechanical means.

On the other hand, if a magnesium chloride discharge device 7 is provided in the reduction device as shown in FIG. 1, and most of the magnesium chloride present in the upper part of the crucible is discharged in a molten state before the crucible 2 is taken out from the furnace 1, After the crucible is cut as described above, it is possible to eliminate magnesium chloride discharge from the upper part of the crucible by a mechanical method.

According to the method of the present invention, the cut upper part of the crucible from which most of the magnesium chloride has been discharged is joined to a new lower part of the crucible, or the contents are recovered and joined again to the empty lower part of the crucible. It is used for the reduction reaction, but until it is bonded to the lower part of the crucible, the deposits in the upper part of the crucible, which mainly consist of zirconium, are shielded from the outside air by the following means to prevent the adsorption of moisture in the atmosphere. .

That is, (1) placing the cut upper part of the crucible or the thin metal cylinder on which zirconium or the like is to be deposited on the inner wall in a normal drying chamber; (2) placing a lid on the crucible upper part or the metal cylinder; Alternatively, put it in an airtight container and evacuate. (3) Fill the metal cylinder or container with inert gas according to method (2) above. (4) Cover the deposit with a waterproof covering such as vinyl. .

The operation of the method of the invention will now be illustrated by the following examples.

EXAMPLE 9 Metallic magnesium 900 was charged into a crucible 2 with an inner diameter of 109 CIn and a height of 225 cm arranged as shown in Fig. 2.
The crucible 2 was placed in the furnace 1.

After the temperature of the furnace 1 was raised to 800° C. to melt the magnesium in the crucible 2, zirconium tetrachloride vapor was blown into the crucible 2 from above to perform a reduction reaction.

After the reaction is complete, the crucible 2 taken out from the furnace 1 is heated to 70C from the bottom.
After cutting at the position I11 and removing the magnesium chloride deposited in the lower part of the crucible, a zirconium sponge weighing about 1000 kg was obtained through a vacuum distillation operation.

On the other hand, after extruding most of the magnesium chloride packed inside the cut crucible using a hydraulic press, the upper part of the crucible was approximately 100 to 200
It was stored in a drying room with the ICG zirconium still attached.

During this time, the lower part of the crucible was subjected to vacuum distillation, and then the produced zirconium sponge was taken out and emptied.

The upper part of the crucible was taken out of the drying room, welded together with the lower part of the crucible, and 900 Icg of magnesium was charged again.
It was used in the reduction reaction.

After the reduction reaction, the same operation as above was performed, but the amount of zirconium attached to the inner wall of the crucible was approximately 100 to 200.
It was about the same amount as last time in kg.

As is clear from the above description, according to the method of the present invention, (1) produced metals attached to the inner wall of the crucible, which could only be used as raw materials for discarded low-grade products, can be Product yield = ! Shi improved by more than 5 units.

(2) The work step of removing deposits from the crucible wall after each reaction is no longer necessary, and labor savings can be achieved in this respect.

(3) The deposits on the inner wall surface of the upper part of the crucible act as a kind of heat insulator during the reduction reaction, so even if the temperature inside the crucible rises abnormally due to the heat generated by the reduction reaction of the raw metal chloride,
Does not alloy with the crucible wall.

Therefore, compared to the conventional method, the introduction rate of raw material chloride was reduced by about 2
I was able to increase the number by 0.

(4) Since the deposits do not adsorb oxygen mainly due to moisture,
A product with low oxygen content and low hardness was obtained.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal cross-sectional views showing an example of a reduction apparatus that is conventionally known and can be used to carry out the method of the present invention. In the figures, each reference number represents the following member. 1... Furnace, 2... Crucible, 3... Curved steam introduction pipe, 4... Guide pipe, 5... Zirconium, 6... ...Magnesium chloride, 7...
... Magnesium chloride discharge device.

Claims (1)

[Scope of Claims] 1. A crucible from which spongy zirconium can be deposited is removed from a reduction reaction device for reducing zirconium tetrachloride with metallic magnesium to produce spongy zirconium, and is cut into a relatively large amount. In a method of separating and recovering spongy zirconium by dividing the crucible into a lower crucible that can hold zirconium and an upper crucible that can hold a relatively small amount of zirconium, while removing most of the by-product magnesium chloride present in the crucible, After removing most of the magnesium chloride from the upper part of the crucible, the relatively small amount of zirconium supported on the inner wall of the upper part of the crucible is kept dry, and the upper part of the crucible is joined and integrated with the empty lower part of the crucible for reuse. A method for reducing zirconium tetrachloride, characterized by: 2. The method for reducing zirconium tetrachloride according to claim 1, wherein the zirconium is adhered to the inner wall of a thin metal cylinder that is placed in close contact with the inner wall of the crucible.