KR20200122927A - Apparatus for Electrolytic Reduction and Method for Electrolytic Reduction - Google Patents

Abstract

The present invention provides an electrolytic reduction apparatus and an electrolytic reduction method which can increase the efficiency of electrolytic reduction. The electrolytic reduction apparatus comprises: a cathode unit of a vessel shape with an opened upper portion which includes a bottom unit and a sidewall unit, and fills metal (loid) oxide in an internal space; a support wall unit separated along the inside of the sidewall unit of the cathode unit to be arranged; a porous plate unit arranged on the inner surface of a lower portion of the support wall unit; and a carbon-based anode unit arranged to come in contact with molten salt in an internal space formed by the support wall unit and the porous plate unit. The electrolytic reduction method comprises: a step of filling metal (loid) oxide in at least a portion of an internal space formed by the sidewall unit, the bottom unit, the support wall unit, and the porous plate unit of the electrolytic reduction apparatus; a step of accommodating molten salt in at least a portion of an internal space formed by the support wall unit and the porous plate unit; and a step of supplying a current to the cathode unit and the carbon-based anode unit to perform electrolytic reduction.

Description

Electrolytic reduction apparatus and electrolytic reduction method {Apparatus for Electrolytic Reduction and Method for Electrolytic Reduction}

The present invention relates to an electrolytic reduction device and an electrolytic reduction method for producing a solid (semi) metal from a (semi) metal oxide using electrolytic reduction.

The recycling of spent nuclear fuel, which is a nuclear fuel after being used as fuel in a nuclear reactor, is a process of separating and extracting uranium and plutonium contained in spent nuclear fuel, and is largely divided into wet treatment and dry treatment. First, wet processing technology is strictly controlled internationally because it can separate plutonium that can produce nuclear weapons alone, whereas dry processing technology cannot purely separate plutonium contained in spent nuclear fuel. It is a difficult technique to use. One of these dry processing technologies is'Pyro-processing'.

Pyro-processing technology is a technology that converts spent nuclear fuel in the form of oxides generated in light water reactors into (semi)metal form and recycles it as nuclear fuel for sodium-cooled high-speed reactors. In general, pyroprocessing technology is a mechanical pretreatment process-volatile oxidation (Voloxidation) process-oxide electrolytic reduction process-electrorefining process-electro smelting process-electrodeposit recovery process-uranium casting process-waste gas treatment process-salt recovery process-waste Includes a treatment process.

In the pyroprocessing technology, the electrolytic reduction process of oxides is a process for reducing fuel materials composed of (semi)metal oxides, that is, spent nuclear fuel prior to electrorefining. At this time, the molten salt is electrolyzed at the cathode to generate a reduced metal derived from the molten salt, and the reduced metal derived from the molten salt reduces the (semi)metal oxide to produce a solid (semi)metal.

In the electrolytic reduction process using LiCl in which a small amount of Li ₂ O is dissolved as a commonly used molten salt, Li ₂ O or LiCl is electrolyzed to produce Li and O ₂ or Cl ₂ , and Li is a (semi)metal oxide Is reduced. When the electrolytic reduction reaction is performed in this way, gas such as oxygen gas or chlorine gas is generated, so that the conventional electrolytic reduction device uses a material having excellent oxidation resistance as a cathode material, especially a platinum material. However, the oxidation resistance is excellent platinum anode is expensive, and delivered in a reducing step is dissolved by the liquid Li metal produced, Li ₂ PtO not only oxidized to the _third embodiment, particularly LiCl-Li Li ₂ O in the ₂ O molten salt When the concentration of is less than 0.5 wt%, a phenomenon in which the platinum anode melts was observed, resulting in a problem of poor stability during the process.

Thus, a carbon-based anode was applied instead of a platinum-based anode, but the carbon dioxide generated from the carbon-based anode reacted with oxygen ions (O ^2- ) of molten salt (Li ₂ O), resulting in a carbonate of lithium carbonate (Li ₂ CO ₃ ). Ions are generated, and the generated carbonate ions may react with Li metal or cause side reactions that cause a parasitic reaction to generate oxygen with carbon particles by receiving electrons at the cathode. These side reactions lowered the current efficiency and caused a problem of reducing the efficiency of reducing the (semi) metal oxide to (semi) metal, and the produced carbon particles were reduced to lower the quality of the generated metal. .

In particular, in the conventional electrolytic reduction apparatus, since the Li metal generated in the cathode can move in all directions inside the free molten salt, as the Li metal reaches the anode, there is a problem of causing a side reaction as described above.

The present invention is to solve the above problems, and while using a carbon-based anode, it prevents the diffusion of the reduced metal (eg, Li metal) derived from the molten salt generated in the cathode into the molten salt, and occurs at the anode. An electrolytic reduction device and electrolytic reduction method that prevents the phenomenon that the carbon-based impurities (for example, carbon particles, etc.) deteriorate the quality of the final produced solid (semi) metal, and ultimately increases the efficiency of electrolytic reduction. Want to provide.

According to an embodiment of the present invention, a cathode portion having a bottom portion and a side wall portion, and a cathode portion in the shape of an upper opening type container for filling (semi) metal oxides into the inner space; A support wall portion spaced apart from and disposed along the inside of the side wall portion of the cathode portion; A porous plate portion disposed on an inner surface of a lower portion of the support wall portion; And a carbon-based anode portion disposed to contact the molten salt in an inner space consisting of the support wall portion and the porous plate portion.

In addition, according to another embodiment of the present invention, the step of filling (semi) metal oxide into at least a portion of the inner space consisting of the side wall portion, the bottom portion, the support wall portion and the porous plate portion of the electrolytic reduction device described above; Accommodating molten salt in at least a portion of the inner space formed of the support wall portion and the porous plate portion; And performing electrolytic reduction by supplying current to the cathode and the carbon-based anode.

The electrolytic reduction device of the present invention includes a cathode portion in the shape of a container with an upper opening for filling the inner space with (semi) metal oxide, and thus reduced metals derived from molten salts (eg, Li metal, etc.) ) Generation is limited to the bottom and sidewalls of the inside of the cathode, not the outside of the cathode, and the molten salt of Li metal is derived by filling the portion where the reduced metal derived from the molten salt is generated as above. There is an effect of preventing the current efficiency of the electrolytic reduction reaction from deteriorating due to the diffusion of the reduced metal of the molten salt directly into the molten salt.

In addition, by including a porous plate portion on the inner surface of the lower portion of the support wall portion disposed inside the cathode portion, reducing metal derived from molten salt such as Li metal generated inside the cathode portion is prevented from reaching the carbon-based anode portion. , The effect of ultimately improving the efficiency of electrolytic reduction by preventing carbon-based impurities (for example, carbon particles, etc.) generated from the carbon-based anode from reaching the cathode through the molten salt and deteriorating the quality of the solid metal. There is.

Furthermore, unlike the conventional electrolytic reduction device in which the enlargement of the device was inevitable in order to accommodate a large amount of molten salt (electrolyte) compared to the solid (semi) metal generated from the (semi) metal oxide, the present invention is There is also an effect that the apparatus can be downsized by using the container itself for receiving the over-molten salt as the cathode.

In addition, as the carbon-based anode part is disposed above the inner space composed of the support wall part and the porous plate part, and a flow path for discharging oxygen gas or chlorine gas is included inside the carbon-based anode part, a separate cover member (e.g. For example, there is an effect of preventing a decrease in electrolytic reduction efficiency due to oxygen gas or chlorine gas without a shroud.

1 is a schematic view showing an electrolytic reduction device according to an embodiment of the present invention.
2 is a schematic view showing an electrolytic reduction device according to the prior art.
3 is a cross-sectional view of a structure in which a (semi)metal oxide is filled and molten salt is accommodated in at least a part of an internal space composed of a bottom portion, a sidewall portion, a support wall portion, and a porous plate portion of a cathode according to an embodiment of the present invention. It is a city schematically showing.
4 is a schematic view showing the structure of a carbon-based anode according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides an electrolytic reduction device.

1 schematically shows an electrolytic reduction device according to an embodiment of the present invention.

The electrolytic reduction device includes a bottom portion 102 and a side wall portion 101, and includes a cathode portion 100 in the shape of an upper opening type container for filling the (semi) metal oxide 10 in the inner space; A support wall portion 200 spaced apart from and disposed along the inner side of the side wall portion 101 of the cathode portion 100; A porous plate portion 300 disposed on an inner surface of a lower portion of the support wall portion 200; And a carbon-based anode part 400 disposed to contact the molten salt 20 in an inner space formed of the support wall part 200 and the porous plate part 300.

The cathode part 100 has an inner space for filling the (semi) metal oxide 10 and may be in the shape of a columnar container having an upper opening. Therefore, the cathode part 100 can accommodate the (semi) metal oxide 10 and the molten salt 20, thus serving as an electrolytic reduction reactor and at the same time as an electrode. Accordingly, the electrolytic reduction reaction is possible with only a small amount of molten salt compared to the content of the solid (semi) metal produced by reduction from the (semi)metal oxide 10, thereby making it possible to reduce the size of the electrolytic reduction device.

In the cathode part 100, the molten salt 20 is electrolyzed and reduced in-situ to form a reduced metal derived from the molten salt 20, and the reduced metal derived from the molten salt 20 is Chemical reaction with the (semi) metal oxide 10 is reduced to a solid (semi) metal.

As shown in FIG. 2, the conventional electroreduction device is composed of a cathode portion and an anode portion facing side by side by being partially immersed in the molten salt. There is a problem in that the reduction of (semi)metal oxides to solid (semi)metals is inhibited by wearing out the anode or causing a side reaction of oxidizing or forming carbon-based impurities at the anode.

In the electrolytic reduction device of the present invention, (semi)metal oxide 10 is filled in at least a part of the inner space consisting of the side wall part 101, the bottom part 102, the support wall part 200, and the porous plate part 300 Can be. Accordingly, the reduced metal derived from the molten salt can be generated only in the bottom portion 102 and the sidewall portion 101 inside the cathode portion 100, not outside the cathode portion 100, and the filled (quasi ) The metal oxide 10 prevents the free diffusion of the reduced metal derived from the molten salt into the molten salt 20, thereby solving the existing problems as described above.

The (semi) metal oxide 10 may be a spent nuclear fuel used for pyroprocessing, and specifically may include uranium oxide (UO ₂ ).

The (semi)metal oxide 10 includes all metal oxides or semimetal oxides, and specifically, may include at least one selected from uranium oxide, titanium oxide, silicon oxide, tantalum oxide, and mixtures thereof. , But is not limited thereto.

The (semi) metal oxide 10 may be in the form of powder, granules, pulverized pellets, porous pellets, high density pellets, etc. having a maximum diameter of 1 cm or less.

The (semi)metal oxide 10 may be filled to a position equal to or higher than the level of the molten salt 20. When the (semi) metal oxide 10 is filled only to a position lower than the liquid level of the molten salt 20, the molten salt 20 permeates toward the (semi) metal oxide 10 and the cathode ( Pass through the (semi) metal oxide portion filled between the side wall portion 101 of 100) and the support wall portion 200 and seep thereon, so that the molten salt 20 can be filled to the same height as the liquid level of the molten salt. In this way, the reduced metal derived from the molten salt generated in the sidewall portion 101 of the cathode portion 100 not in contact with the (semi) metal oxide 10 was filled on the (semi) metal oxide 10 portion. There is a problem that it can be freely moved toward the molten salt 20.

In addition, the (semi)metal oxide 10 may be filled to a position equal to the level of the molten salt 20 or higher by a height of about 0.5 cm or less. As described above, the molten salt 20 accommodated in at least a part of the inner space composed of the support wall part 200 and the porous plate part 300 is provided with the side wall part 101 of the cathode part 100 and the support wall part ( 200) can penetrate into the (semi) metal oxide 10 filled between the molten salts. According to the experiment of the present inventor, even the (semi) metal oxide filled to a position about 0.5 cm higher than the level of the molten salt It was confirmed that this permeation.

The cathode portion 100 may be formed of a material such as stainless steel (304, 316L), Inconel, or the like.

The support wall portion 200 may be disposed to be spaced apart along the inner side of the side wall portion 101 of the cathode portion 100. The support wall part 200 may have a hollow column shape so as to be matched with the cathode part 100.

The support wall part 200 may be disposed independently from the cathode part 100 or the carbon-based anode part 400, or may be disposed in a form detachably connected to any one of them. For example, the support wall part 200 may be integrally connected to the upper end of the sidewall part 101 of the cathode part 100 or may be detachably connected through a connection part 30 such as a hook shape.

Since the support wall part 200 is formed of an insulating material, it may serve to electrically insulate the carbon-based anode part 400 and the cathode part 100. In addition, in the support wall part 200, the (semi) metal oxide 10 filled in at least a part of the inner space between the side wall part 101 of the cathode part 100 and the support wall part 200 is the molten salt ( 20) It can also serve as a support that prevents it from flowing down into the interior. Accordingly, the support wall part 200 may be disposed to have a height higher than a height at which the (semi) metal oxide 10 is filled.

In addition, the inner surface of a part of the lower part of the support wall part 200 is in contact with the (semi) metal oxide 10 and the molten salt 20, and the outer surface of a part of the lower part of the support wall part 200 is (semi) It may be in contact with the metal oxide 10. That is, a part of the inner space of the lower part of the support wall part 200 may be filled with (semi) metal oxide 10, and the (semi) part of the inner space of the lower part of the support wall part 200 is filled. The molten salt 20 may be accommodated on the metal oxide 10.

The support wall part 200 may be a material through which the (semi) metal oxide 10 or the molten salt 20 does not pass, and may include a material having mechanical stability while having corrosion resistance in a high-temperature molten salt. I can. Specifically, the material of the support wall part 200 may include at least one selected from magnesia (MgO), yttria (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), and mixtures thereof, and magnesia (MgO ), yttria (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), or at least one selected from a metal material coated with a mixture thereof.

The porous plate portion 300 may be disposed on an inner surface of the lower portion of the support wall portion 200. Specifically, the porous plate portion 300 may be disposed on an inner surface of a portion of the lower portion of the support wall portion 200, and the molten salt 20 accommodated in an inner space of a portion of the lower portion of the support wall portion 200 Can be placed within.

The porous plate portion 300 can pass the molten salt 20, but the reduced metal derived from the molten salt generated in the cathode portion 100 by an electrolytic reduction reaction is transferred to the carbon-based anode portion 400. In contrast, the carbon-based impurities generated in the carbon-based anode part 400 can be prevented from being transferred to the (semi) metal oxide 10, thereby enhancing the efficiency of electrolytic reduction.

The porous plate portion 300 may be formed of a mesh diaphragm, and may be formed of a diaphragm having a plurality of overlapping mesh structures, for example, a five-ply mesh structure.

The material of the porous plate portion 300 is not limited thereto, as long as it is a material having strong corrosion resistance such as stainless steel or Inconel.

The molten salt 20 may be accommodated in at least a part of the inner space formed of the support wall part 200 and the porous plate part 300. In addition, some of the molten salt 20 may be impregnated in the (semi)metal oxide 10. The molten salt 20 may be in a liquid state.

The molten salt 20 may be an electrolyte containing an alkali metal element or an alkaline earth metal element, and specifically, may include at least one electrolyte selected from lithium chloride, calcium chloride, lithium oxide, calcium oxide, and mixtures thereof. have.

The molten salt 20 may be obtained by heating at least one selected from lithium chloride, calcium chloride, lithium oxide, calcium oxide, and mixtures thereof to 550°C or higher, specifically 550 to 650°C.

In addition, an inert gas, for example, argon (Ar), etc., may be accommodated other than the inner space in which the molten salt 20 is accommodated, among at least a portion of the inner space formed of the support wall part 200 and the porous plate part 300. .

The reduced metal derived from the molten salt may be an alkali metal or alkaline earth metal, such as lithium or calcium, generated by electrolysis of the molten salt 20 in the negative electrode part 100.

The electrolytic reduction device moves oxygen ions derived from (semi)metal oxides 10 at the lower end of the support wall part 200 to the molten salt 20 that the carbon-based anode part 400 is in contact with. It may further include a porous flow path portion 500 for.

The porous flow path part 500 is a hollow basket made of a porous double plate, and may be disposed in a space filled with the (semi)metal oxide 10.

The hollow basket may include a hollow (internal space) between the double plates since the porous flow path part 500 is formed of a porous double plate.

The porous double plate of the porous passage part 500 does not pass through the solid (semi) metal obtained by reduction from the (semi) metal oxide 10, and the oxygen ions derived from the (semi) metal oxide 10 pass. It can act as a channel for oxygen ions. Accordingly, compared to the case where only the (semi) metal oxide 10 is filled, the oxygen ion movement speed occurs much faster, and thus the carbon-based anode part 400 can be moved faster.

In this case, the molten salt 20 may be accommodated in the hollow (internal space) between the double plates of the porous flow path part 500.

The carbon-based anode part 400 may be disposed so as to contact the molten salt 20 in an inner space composed of the support wall part 200 and the porous plate part 300. In addition, the carbon-based anode part 400 may include a flow path for discharging oxygen gas or chlorine gas generated in the electrolytic reduction reaction therein.

The flow of oxygen gas or chlorine gas occurring in the carbon-based anode part 400 and the carbon-based anode part 400 according to an embodiment of the present invention is schematically shown in FIG. 4.

The carbon-based anode part 400 has a plurality of lower portions of the carbon-based anode part 400 immersed in the molten salt 20 or the side of the carbon-based anode part 400 not immersed in the molten salt 20 It may contain a flow path (hollow). It is possible to facilitate the discharge of oxygen gas or chlorine gas generated through the plurality of flow paths (hollows).

The carbon-based anode part 400 may further include a flange 401 attached to the carbon-based anode part 400. The flange 401 is disposed above the carbon-based anode part 400 so that the carbon-based anode part 400 is fixed to the cover 600 for sealing the upper part of the cathode part 100.

The flange 401 may be made of a material such as metal, such as stainless steel, which is resistant to high temperatures.

Conventionally, a cover member (for example, a shroud) is separately installed around the anode to prevent the oxygen gas or chlorine gas generated by the electrolytic reduction reaction from corroding the interior of the device or reacting with reactants and products. Thus, the gas was discharged to the outside of the apparatus while being stored in the anode.

However, in the electrolytic reduction device according to the present invention, in particular, the carbon-based anode part 400 is disposed above the inner space composed of the support wall part 200 and the porous plate part 300, and a flow path for discharging gas is provided therein. As a result, since the carbon-based anode part 400 serves as a cover member such as a shroud, it is possible to prevent a decrease in electrolytic reduction efficiency due to oxygen gas or chlorine gas without a separate cover member.

That is, the carbon-based anode part 400 may not substantially include a separate cover member for discharging oxygen gas or chlorine gas generated in the electrolytic reduction reaction. Substantially not including the separate cover member means that the electrolytic reduction device no longer includes a separate cover member such as a shroud as the carbon-based anode part 400 serves as a cover member. can do.

The electrolytic reduction device may further include a cover 600 for sealing an upper portion of the cathode part 100, and a part of the cover 600 is an internal space for containing the carbon-based anode part 400 It may include.

A discharge part 40 for facilitating the discharge of gas may be further included in a portion where one end of the carbon-based anode part 400 contacts at least a part of the cover 500.

The electrolytic reduction device may further include a heating unit (not shown in the drawing) for heating the (semi) metal oxide 10 and the molten salt 20, and the heating unit may further include an electrolytic reduction reaction. , It is possible to use a heating unit such as an electric furnace for ordinary heating without limitation.

In addition, the electrolytic reduction device may further include a support part (not shown in the drawing) for supporting the negative electrode part 100, and the support part does not affect the electrolytic reduction reaction, and supports the negative electrode part 100 As long as it can be done, the material or its shape is not limited.

The support may further include a temperature control member for controlling the temperature of the electrolytic reduction reaction.

The electrolytic reduction device may further include an electric device (not shown in the drawing) capable of supplying current to the cathode part 100 and the carbon-based anode part 400, and the electric device includes the cathode part ( 100) and the carbon-based anode part 400, as long as a voltage is applied to supply current, a conventional electric device may be used without limitation.

In addition, the present invention provides an electrolytic reduction method.

The electrolytic reduction method includes the steps of filling (semi) metal oxide into at least a portion of an inner space composed of the sidewall part, the bottom part, the support wall part, and the porous plate part of the electrolytic reduction device described above; Accommodating molten salt in at least a portion of the inner space formed of the support wall portion and the porous plate portion; And performing electrolytic reduction by supplying current to the cathode and the carbon-based anode.

At this time, the (semi)metal oxide may be filled to a position equal to or higher than the level of the molten salt.

For the (semi) metal oxide, molten salt, cathode portion, support wall portion, porous plate portion, and carbon-based anode portion, the same descriptions of the electrolytic reduction apparatus may be applied.

In addition, the electrolytic reduction method may be obtained by heating at least one selected from the lithium chloride, calcium chloride, lithium oxide, calcium oxide, and mixtures thereof to 550°C or higher, specifically 550 to 650°C.

The step of supplying current to the cathode and the carbon-based anode may include applying a voltage negative to the reduction potential of the molten salt cation and the (semi) metal oxide cation to the cathode; And applying a voltage positive to the oxidation potential of the molten salt anion and/or the oxygen ion derived from the (semi)metal oxide to the carbon-based anode.

According to an embodiment of the present invention, a LiCl-Li ₂ O electrolyte may be used as the molten salt, and an electrolytic reduction device and an electrolytic reduction method for pyroprocessing using UO ₂ as the (semi) metal oxide are provided. do.

In the above electrolytic reduction process, Li ₂ O is electrolyzed at the cathode portion as shown in Equation (1) below to generate a reduced metal (Li) and oxygen gas (O ₂ ) derived from a molten salt, as shown in Equation (2) below. Likewise, Li reduces UO ₂ and generates new Li ₂ O again, so that the amount of Li ₂ O in the electrolytic reduction device can be kept constant, so that LiCl can be used continuously and the addition of Li metal is not required. There is this.

[Equation (1)]

２Li ₂ O ⇔ 4Li + O ₂ (electrolysis)

[Equation (2)]

UO ₂ + 4Li ⇔ U + 2Li ₂ O (reduced)

[Equation (3)]

UO ₂ ⇔ U + O ₂ (total reaction)

Meanwhile, in the carbon-based anode part, by reacting with oxygen ions derived from (semi) metal oxide, carbon dioxide (CO ₂ ) is generated as shown in the following formula (4), and Li generated in the cathode part is converted into the molten salt. It is diffused and reacts with carbon dioxide (CO ₂ ) generated in the carbon-based anode portion to generate carbon-based impurities (carbon particles (C), etc.).

[Equation (4)]

C (carbon) 2O ^2- + CO ⇔ ₂ + 4e ^-

[Equation (5)]

2Li + CO ₂ ⇔ 2Li ₂ O + C (carbon)

In addition, carbon dioxide (CO ₂ ) generated from the carbon-based anode reacts with oxygen ions (O ^2- ) of Li ₂ O as shown in Equation (6) below, and the carbonate ions (CO ₃ ² ) of lithium carbonate (Li ₂ CO ₃ ) ^-) a can be produced, the carbonate ion is the following formula (7) to react with Li metal, or as in equation (8) e (e in the cathode part as shown ^- and s) for receiving carbon particles (C) Side reactions that generate oxygen (O ₂ ) may occur.

[Equation (6)]

CO ₂ + Li ₂ O ⇔ Li ₂ CO ₃ ⇔ ₂ Li ⁺ + CO ₃ ^2-

[Equation (7)]

^{_{CO 3 2- + 2Li ⇔ Li 2}} CO 3 + 2e -

[Equation (8)]

2CO ₃ ^2- + 2e ^- ⇔ 2C + 3O ₂

As described above, according to the electrolytic reduction device and the electrolytic reduction method of the present invention, as the cathode has an inner space for filling (semi) metal oxide (UO ₂ ), and has a columnar container shape of an upper opening , Reduced metal (Li) derived from molten salt is generated only at the bottom and sidewalls of the inside of the cathode, not outside of the cathode, and the reduced metal derived from the molten salt due to the (semi) metal oxide (UO ₂ ) filled (Li) has the effect of preventing free diffusion into the molten salt (LiCl-Li ₂ O).

Further, as the porous plate-shaped portion is included, the molten salt (LiCl-Li ₂ O) is passed through, while the reduced metal (Li) derived from the molten salt generated in the cathode portion is moved to the carbon-based anode portion by an electrolytic reduction reaction. In contrast, the carbon-based impurities (carbon particles (C)) generated in the carbon-based anode portion can be prevented from being transferred to the (semi)metal oxide (UO ₂ ), and thus the molten salt-derived There is also an effect of increasing the efficiency of electrolytic reduction by suppressing side reactions caused by reducing metal (Li) and carbon-based impurities (carbon particles (C)).

100: cathode
101: side wall portion
102: bottom
200: support wall portion
300: porous plate portion
400: carbon-based anode portion
401: flange
500: porous flow path portion
600: cover
10: (semi) metal oxide
20: molten salt
30: connection
40: discharge unit
1: cathode basket
2: cathode
3: heating furnace
4: gas discharge pipe
5: heat sink
6: electrolyzer
7: anode
8: anode shroud

Claims (20)

A cathode portion in the shape of an upper opening type container including a bottom portion and a side wall portion, and for filling (semi) metal oxides in the inner space;
A support wall portion spaced apart from and disposed along the inside of the side wall portion of the cathode portion;
A porous plate portion disposed on an inner surface of a lower portion of the support wall portion; And
A carbon-based anode portion disposed to contact the molten salt in an inner space consisting of the support wall portion and the porous plate portion;
Electrolytic reduction device comprising a. The method according to claim 1,
An electrolytic reduction device in which (semi)metal oxide is filled in at least a part of an inner space consisting of the side wall part, the bottom part, the support wall part, and the porous plate part. The method according to claim 2,
The electrolytic reduction device in which molten salt is accommodated in at least a part of the inner space composed of the support wall portion and the porous plate portion. The method of claim 3,
The (semi)metal oxide is filled to a position equal to or higher than the level of the molten salt. The method according to claim 1,
The (semi) metal oxide is an electrolytic reduction device comprising at least one selected from uranium oxide, titanium oxide, silicon oxide, tantalum oxide, and mixtures thereof. The method according to claim 1,
The molten salt includes at least one electrolyte selected from lithium chloride, calcium chloride, lithium oxide, calcium oxide, and mixtures thereof. The method according to claim 1,
The electrolytic reduction device that the cathode part has a columnar container shape. The method of claim 7,
The electrolytic reduction device in which the support wall portion has a hollow column shape to match the cathode portion. The method according to claim 1,
Electrolytic reduction device further comprising a connection portion for fixing the support wall portion to the cathode portion. The method according to claim 1,
The electrolytic reduction device that the support wall portion is formed of an insulating material. The method according to claim 1,
The porous plate portion inhibits the transfer of the reduced metal derived from the molten salt generated in the cathode portion to the anode portion by an electrolytic reduction reaction, and the carbon-based impurities generated in the carbon-based anode portion is the (semi)metal oxide Electrolytic reduction device for suppressing the movement to. The method of claim 11,
The electrolytic reduction device of the porous plate portion is formed of a mesh diaphragm. The method according to claim 1,
The electrolytic reduction device further comprises a porous flow path for moving oxygen ions derived from (semi)metal oxides to the molten salt in contact with the carbon-based anode at the lower end of the support wall. The method of claim 13,
The electrolytic reduction device in which the porous flow path part is a hollow basket made of a porous double plate. The method according to claim 1,
The electrolytic reduction device of the carbon-based anode unit comprising a flow path for discharging oxygen gas or chlorine gas generated in the electrolytic reduction reaction. The method according to claim 1,
The electrolytic reduction device of the carbon-based anode part substantially does not include a separate cover member for discharging chlorine gas generated in the electrolytic reduction reaction. The method according to claim 1,
Electrolytic reduction device further comprising a cover for sealing the upper portion of the cathode. Filling (semi) metal oxide into at least a portion of the inner space consisting of the sidewall portion, the bottom portion, the support wall portion, and the porous plate portion of the electrolytic reduction device of claim 1;
Accommodating molten salt in at least a portion of the inner space formed of the support wall portion and the porous plate portion; And
Performing electrolytic reduction by supplying current to the cathode and the carbon-based anode;
Electrolytic reduction method comprising a. The method of claim 18,
The electrolytic reduction method of the (semi) metal oxide is filled to a position equal to or higher than the level of the molten salt. The method of claim 18,
The step of supplying current to the negative electrode and the carbon-based positive electrode may include applying a voltage negative to the reduction potential of the cation of the molten salt and the cation of the (semi) metal oxide to the negative electrode; And applying a positive voltage to the carbon-based anode portion rather than the oxidation potential of the molten salt anion or the oxygen ion derived from the (semi)metal oxide.

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