JPS5846555B2 - Denkaisou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic cell, and in particular to a molten salt electrodeposition method that allows deposited metals (including alloys), such as titanium, to be formed into any desired shape, such as a smooth plate or a lump. Relates to electrolytic cells used for

Conventionally, the electrolyzed product obtained by the general molten salt electrodeposition method has been in the form of a melt, a granular powder, or a sponge.

Therefore, research has been conducted on electrodeposition methods that can shape the electrolyzed product into a smooth plate shape.
The electrodeposition methods shown in No. 94943 and No. 726754 were provided by the present inventors.

For example, the electrodeposition method disclosed in the above-mentioned No. 726754 uses at least barium chloride, magnesium chloride,
A molten salt bath containing a combination bath of a four-component system consisting of sodium chloride and calcium chloride whose solidification point is below 600°C and a low-valent compound of a desired metal, such as titanium, is used. Part or all at least 500℃
The desired metal, such as titanium, is heated to a temperature above to adjust the bath condition, and the high valence compound of the metal in the bath near the electrode where the desired metal, for example titanium, is electrodeposited is adjusted to the molar ratio of the analytical value at room temperature. While maintaining the low valence of metal compounds to 7 or less,
Electrodeposition is performed at a temperature of 00 to 580°C.

In this electrodeposition method, the composition of the molten salt bath is important, as well as the ionic state of the molten salt, including the electrodeposited metal ions, the molten state in the molten salt, and the crystal composition state of crystallization. is also one of the important factors.

In other words, the temperature range of the electrolytic bath in the electrolytic bath has at least two parts: a temperature part near the cathode insertion part (low temperature part) and another part whose temperature is higher than that temperature part (high temperature part). This is an important element.

To explain further, in this electrodeposition method, the molten salt bath composition is a supersaturated composition at the electrolysis temperature.

Therefore, if the entire electrolytic cell is kept at the electrolysis temperature for a long time, the supersaturated components will crystallize, the crystals will grow, and even if the electrolytic bath is stirred, they will remain suspended in the electrolytic bath. gradually becomes impossible.

Furthermore, the crystal composition of the supersaturated component also changes due to cooling, and the state of the electrodeposited metal ions also changes.

When the electrodeposited metal ion is a polyvalent metal, the ion state changes further due to a disproportionation reaction or the formation of a complex.

From this fact, even if the molten salt element ratio in the cathode insertion part can be kept almost constant at the electrolysis temperature, the condition of the electrodeposit deteriorates during long-term electrolysis.

Therefore, in order to perform long-term electrolysis satisfactorily, it is necessary to raise the temperature of the molten salt bath to at least the electrolysis temperature.

For example, to describe an electrolytic cell for smooth electrodeposition of titanium metal, there is a low-temperature section where the cathode is placed, which is maintained at an electrolysis temperature below the liquidus line of the molten salt composition, and a temperature higher than that of this section. It is desirable to have a high-temperature section that heats to an extent that melts at least a portion of the excess molten salt composition crystallized at the electrolysis temperature and restores the function of the molten salt.

By circulating the electrolytic bath between the second low temperature section and the high temperature section, it is possible to restore the function of the molten salt bath continuously and automatically while continuing electrodeposition. In this case, due to the large temperature difference, a solidified film, that is, a crust or a scale, forms at the contact area between the plow bath surface and the wall surface of the electrolytic cell.
It was recognized that these changes the flow near the bath surface of the electrolytic bath, which interferes with good electrolysis over a long period of time.

The present invention inhibits such growth of last or scale and enables good electrolysis over a long period of time.

That is, in the present invention, there is provided a crushing means for crushing the crust and scale of a tank containing a molten salt electrolytic bath by continuously or periodically applying an impact to the surface of the bath or shaking and stirring the bath. will be established.

In addition, in order to prevent the airtightness of the electrolytic bath from being damaged by providing this crushing means and the electrolytic bath coming into contact with air and being oxidized, at least the surface of the electrolytic bath is heated with an inert gas such as argon (Ar). This is to ensure airtightness.

Hereinafter, an example of an electrolytic cell according to the present invention will be explained in detail with reference to FIG. figure).

Inside the tank 1, the electrolytic bath 2 is kept at an electrolysis temperature of, for example, 500°C or less, preferably 480 to 440°C, and includes a low-temperature part 5 in which the cathode 4 is arranged, and a low-temperature part 5 in which the electrolytic bath 2 is kept at an electrolysis temperature of 500°C or less, preferably 480 to 440°C. A high-temperature section 6 is provided in which the electrolytic bath 2 is maintained at a temperature at which it can be sufficiently melted, such as 500° C. or higher, preferably 520 to 560° C., to recover the function of the electrolytic bath 2.

Then, by providing a suitable stirring means, a reflux is generated in the electrolytic bath 2 to form a closed loop in the low temperature section 5 and the high temperature section 6, respectively, and at the same time, the entire space between the low temperature section 5 and the high temperature section 6 is stirred. This also creates a circular flow.

Note that a cooling section 5a is provided in a part of the low temperature section 5.

This cooling section 5a is provided on the upstream side with respect to the overall flow of the electrolytic bath within the low temperature section 5.

In this case, the cathode 4 is disposed on the downstream side with respect to the overall flow of the electrolytic bath outside the portion of the low-temperature section 5 where the cooling section 5a is provided, thereby forming the cathode cooling section 5b.

A closed loop circulation is formed between the cooling section 5a and the cathode cooling section 5b, and at the same time, circulation from the high temperature section 6 to the cooling section 5 to the high temperature section 6 is created.

In this manner, by causing the electrolytic bath 2 to circulate in each of the sections 5a, 5b and 6, the electrolytic bath 2 is allowed to stay in each section 5a, 5b and 6 for the required time.

The high temperature section 6 includes, for example, a deep tank section provided on one side of the tank 1.
The depressed part is the high temperature part 6, the upper part is the cooling part 5a of the low temperature part 5, and the shallow tank part adjacent thereto is the cathode cooling part 5b of the low temperature part 5. Thus, the bottom surface 7 of the cathode cooling part 5b is
It is possible to form a shelf extending above the high temperature part 6 so as to form a shelf.

Further, at least the edge of the bottom surface 7 on the high temperature portion 6 side may be provided with an inclined surface that dips toward the high temperature @6.

Incidentally, the cathode 4 disposed in the low temperature section 5 is moved by rotating it or moving it by one angle.

Further, an anode 8 is arranged opposite to the cathode 4. In the illustrated example, a diaphragm 9 is disposed surrounding the anode 8, thereby preventing the electrolytic bath composition from changing due to anode reaction products generated during electrolysis.

A vertical separator 10 with or without through holes may be disposed between the cooling @5a and the cathode cooling portion 5b.

The temperatures of the cooling section 5a, the cathode cooling section 5b, and the high temperature section of the low temperature section 5 are set so that the electrolytic bath 2 has a required temperature distribution using, for example, an internal heating type heater (not shown) so that the respective temperatures are the same. Do it like this.

Further, the cooling section 5a may be provided with a means for cooling the electrolytic bath 2 as required.

On the other hand, in the electrolytic bath 2, a closed loop circulation is formed in each of the above-mentioned parts 5a, sb and 6, and a part of the circulation is supplied to each part 5a.
, 5b and 6, the stirring means for forming the overall flow circulating between them is constructed by arranging two or more stirring mechanisms 11 to 13 such as propeller screws or helical screws.

For example, the first stirring mechanism 11 is provided in the depressed part, that is, the high temperature part 4 in the deep tank, the second stirring mechanism 12 is provided in the cooling part 5a, and the third stirring mechanism 13 is provided in the cathode cooling part 5b. .

Then, the first to third stirring mechanisms 11 to 13 are operated simultaneously by selecting their efficiency, rotation speed, rotation direction, etc., taking into account, for example, the viscosity, specific gravity, and shape of the electrolytic bath. By doing so, each part 5 is shown with an arrow in FIG.
A, 5b, and 6 can be caused to have a circular flow, and each part can be circulated to each part 6 → 5a → 5b → 6, etc. Furthermore, if necessary, the high temperature part 6 and the cooling part 5a can be circulated. It is possible to form a reflux flow forming another closed loop, which can also be called a grain regulating part, in the intermediate part 14 of the grain size regulating part.

When forming a reflux flow in such an intermediate section 14, the electrolytic bath flow from the low temperature section 5 enters the high temperature section 6, where it is once heated to a high temperature and the sufficiently melted electrolytic bath is sent to the cooling section 5a. Therefore, the effect of adjusting the size and quality of crystallized particles, that is, performing a particle-regulating action.

In the present invention, the tank 1 is provided with a crushing means 15 for crushing crust and scale generated on the surface of the electrolytic bath 2 and its periphery.

The details of this crushing means 15 include, for example, as shown in FIG. An operating rod 17 that moves in the vertical direction so as to enter is provided.

Reference numeral 18 denotes a drive unit, such as an air cylinder, which is connected to the operating rod 17 and drives it to move up and down.

The operating rod 17 penetrates into the tank 1 from outside the tank 1 through a through hole 19 formed in the lid 3, and a seal portion 20 is provided above the through hole 19.
A cannula 21 is attached to support the cylinder 18 through the through hole 19, and the through hole 19 is hermetically sealed by the backing 22 of the seal portion 20.

FIG. 3 shows another example of the crushing means 15. In this example, the crushing means 15 is attached to the lid 3 so that it can swing within the range shown by generatrix lines 23 and 24 in the figure. This is the case when it is installed in

That is, in this case, the swing bearing part 25 is disposed between the lid 3 and the seal part 20, and the swing bearing part 25 has a spherical protrusion 26 on the circumferential surface, for example, under the seal part 20. A tube body 27 having a structure may be attached thereto, and a spherical recess 28 that abuts the spherical surface of the protrusion 26 may be provided on the outer periphery of the protrusion 26.

As in this example, when an impact is applied while the crushing means 15 is oscillated, a solidified film is formed at the contact area with the wall surface of the electrolytic cell.
It is easily peeled off and crushed by being dragged along by the fracture of the film in the center.

However, if the solidification of the wall coating progresses beyond a certain level, it is necessary to provide the impact body 16 directly near the wall surface.

FIG. 4 shows another example of the crushing means 15. In this example, the lower part of the cylinder 18 and the lid 3 are arranged so that the operating position of the impact body 16 can be adjusted according to the position of the bath surface 2a. Tube bodies 29 and 30 that can fit into each other and slide in the axial direction are installed in communication with the through hole 19, and the arrangement height of the cylinder 18,
Therefore, the height position of the impact body 16 can be adjusted.

In this case, the tubes 29 and 30 may be frictionally engaged with each other, or appropriate fixing means (not shown) may be provided to hold the tubes 29 and 30 together.
and 30 can be set to any desired sliding position.

31 is a backing that seals between the tube bodies 29 and 30.

In addition, in FIGS. 3 and 4 described above, parts corresponding to those in FIG. 2 are given the same reference numerals and redundant explanation will be omitted.

Each of the above-mentioned crushing means 15 slams the impact body 16 against the bath surface 2a by reciprocating the operating rod 1T in its axial direction using an air cylinder 18 or by swinging it, thereby causing rocking agitation. In particular, the coagulated film, that is, the crust and scale of the bath 2 caused by the temperature difference mentioned above is crushed.

This crushing operation can be performed continuously or at regular intervals, for example every 30 to 60 minutes.

In addition, an inert gas such as argon is introduced into the space above the bath 2 in the tank 1 so that the surface of the bath 2 is hermetically sealed from the atmosphere.

In other words, it helps maintain airtightness.

When electrodeposition is performed using the electrolytic bath described above, the electrolytic bath 2 has a high temperature section 6 and a low temperature section 5, that is, a cathode cooling section 15b where electrodeposition is performed.
In addition, a crushing means 15 is provided especially in the low-temperature part where hardening (solidification) of the electrolytic bath surface is likely to occur.
is arranged, thereby crushing the hardened or to be hardened portion of the bath 2, effectively preventing the flow of the bath 2 from being obstructed by this hardening, i.e. by crust or scale. It can be avoided.

Therefore, electrodeposition can be continued in good bath conditions for a long period of time.

When the surface of the bath 2 is isolated from the atmosphere using an inert gas, even if the crushing means 15 is disposed through the lid 3 as described above, air may enter the tank through this penetrating portion. It is also possible to effectively avoid the possibility that the liquid comes into contact with the bath 2 and oxidizes the liquid.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an electrolytic cell according to the present invention, and FIG.
4 through 4 are sectional views showing examples of the crushing means. 1 is a tank, 2 is an electrolytic bath, 3 is a lid, 4 is a cathode, 8 is an anode, 5
1 is a low temperature section, 6 is a high temperature section, 15 is a crushing means, 16 is an impact body, 17 is an operating rod, and 18 is an air cylinder.

Claims (1)

[Claims] 1. An electrolytic cell, characterized in that the tank containing the molten salt electrolytic bath is provided with a lid for airtight sealing, and further provided with means for crushing at least the surface coagulated film of the electrolytic bath.