JP6053370B2 - Molten salt electrolysis apparatus and method - Google Patents

Description

  The present invention relates to a molten salt electrolysis apparatus and method, and more particularly, to a molten salt electrolysis apparatus and method for electrolyzing a molten metal chloride and obtaining an electrolysis gas from an anode and an electrolysis genus from a cathode, respectively. Is.

  In recent years, when the molten salt, which is a molten metal chloride, is electrolyzed and the electrolytically generated gas is obtained from the anode and the electrolytically generated metal is obtained from the cathode, heat generation due to liquid resistance of the molten salt is suppressed while downsizing the device configuration. For this reason, attempts have been made to reduce the electrode spacing between the anode and the cathode, but for the reasons described below, it has not been successful to sufficiently reduce the electrode spacing at a practical level. .

  This is because when the electrode interval is reduced, the rate at which the so-called reverse reaction, which is a reaction in which the electrolysis gas and the electrolysis metal are recombined, increases, and the electrolysis current efficiency deteriorates. This is because the electrolysis voltage rises due to the overvoltage generated with the increase in the volume occupation ratio of the electrolysis gas in the meantime, and as a result, the power intensity during electrolysis tends to deteriorate.

  In other words, if the electrode spacing between the anode and cathode is reduced, heat generation due to liquid resistance of the molten salt can be suppressed while downsizing the device configuration, while the power during electrolysis is reduced due to deterioration of the electrolysis current efficiency and increase of the electrolysis voltage. A trade-off relationship occurs in which the basic unit deteriorates.

  Under such circumstances, Patent Document 1 proposes a configuration that is intended to improve the separability between the electrolysis gas and the electrolysis metal by tilting the electrode from the vertical direction in order to suppress the reverse reaction. ing.

No. 03-039488

  However, according to the study by the present inventor, the configuration proposed in Patent Document 1 is intended to improve the separation between the electrolysis gas and the electrolysis metal, but in this configuration, the anode and the cathode When the electrode spacing is further reduced, heat generation due to the liquid resistance of the molten salt can be further suppressed while the device configuration is further reduced, while the electrolytic current efficiency is deteriorated or the voltage between the electrodes is reduced. As a result, an increase in overvoltage exceeding the threshold value occurs, and the phenomenon that the power consumption rate during electrolysis deteriorates cannot be suppressed, and the trade-off relationship again occurs.

  In order to cope with the difficulty of narrowing the electrode spacing, generally, in such a configuration, a mixed salt system in which a molten salt is mixed with a second component not directly involved in electrolysis is used, and the liquid resistance of the mixed molten salt is adopted. By lowering the electrolysis voltage, the electrolysis voltage is lowered to improve the power consumption during electrolysis.

However, according to further studies by the inventor, when such a mixed salt system is employed,
Since it is necessary to eliminate unnecessary influence due to the second component, the apparatus configuration becomes complicated.

  The present invention has been made in view of such circumstances, and can suppress heat generation due to the liquid resistance of the molten salt by narrowing the electrode interval, while suppressing deterioration in electrolytic current efficiency and increase in electrolysis voltage. It is an object of the present invention to provide a molten salt electrolysis apparatus and method capable of improving the power consumption rate of the above.

In order to achieve the above object, the molten salt electrolysis apparatus according to the first aspect of the present invention includes an electrolytic cell for storing a molten salt that is a molten metal chloride as an electrolytic solution, an anode having an anode surface portion, and the anode surface portion. And an electrode unit to be immersed in the molten salt, each of the anode surface portion and the cathode surface portion being perpendicular to a first direction. Each of the anode surface portion and the cathode surface portion facing each other in an inclined inclination direction has a zigzag shape portion, and the zigzag shape portion includes a first inclined surface and a second protrusions extending in the inclined direction while projecting in a second direction perpendicular to the inclined direction with a second inclined surface, and said first inclined surface and the second in the second direction Same as adjacent to inclined surface Valley has a recess which is a groove exhibiting a constant width in a third direction perpendicular to the tilt direction and the second direction while extending in the inclined direction while being Ochii設with, the convex portion及fine the recess, in their state with each other corresponding ones had been adjacent to the inside of the front SL is disposed in the third direction, the distance between the anode surface and the cathode surface portions, 1 mm or more 5mm or less der is a shall.

  Further, in addition to the first aspect, the present invention is such that the inclination angle in the inclination direction of the zigzag shape portion of the anode surface portion and the cathode surface portion is set within a range of 10 degrees to 50 degrees, The convex portion has a pair of slopes that are continuous at a ridge portion, and the zigzag shape portion is set such that an angle with respect to the third direction in each of the pair of slopes is in a range of 5 degrees to 45 degrees. A second aspect is to have a zigzag angle.

The present invention, in addition to such a second aspect, each of the grooves of said recess, said der the width 0.5mm or more in the third direction is, the sum of the width of said groove, said plurality A third aspect is that the anode surface portion and the cathode surface portion provided with the recess are 20% or less of the width in the third direction of the at least one.

  Moreover, in addition to this 3rd aspect, this invention makes it the 4th aspect that the said width | variety of the said groove | channel is expanded in the depth direction of the said groove | channel.

  Moreover, in addition to this 3rd or 4th aspect, this invention makes it the 5th aspect that the said groove | channel has a branched groove | channel or protrusion in the bottom part of the depth direction of the said groove | channel.

  In addition to any of the third to fifth aspects, the present invention further includes a discharge pipe that surrounds the periphery of the groove upper end and opens above the liquid surface of the molten salt. Let it be the sixth aspect.

  In addition to the sixth aspect of the present invention, the seventh aspect is that the material of the exhaust pipe is any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz.

  Further, according to the present invention, in addition to any one of the first to seventh aspects, the anode surface portion and the cathode surface portion are parallel to each other, and an electrolytic reaction space is defined between them. Let's say that.

In addition to the eighth aspect of the present invention, the electrode unit further includes an insulating sheath that covers the outer periphery of the anode and the cathode except for the upper and lower sides of the electrolytic reaction space. Nine aspects.

In addition to the ninth aspect, the present invention has a tenth aspect in which the material of the insulating exterior is any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz.

In addition to any one of the first to tenth aspects of the present invention, the molten salt contains any of sodium chloride, potassium chloride, lithium chloride, calcium chloride, aluminum chloride, magnesium chloride, and zinc chloride. This is the eleventh aspect.

In addition to the eleventh aspect, the present invention has a twelfth aspect that the molten salt is a single salt system containing zinc chloride.

In another aspect, the present invention, in another aspect, comprising an electrolytic cell containing a molten salt that is a molten metal chloride as an electrolyte, an anode having an anode surface portion, and a cathode having a cathode surface portion facing the anode surface portion, An electrode unit to be immersed in the molten salt, and each of the anode surface portion and the cathode surface portion is inclinedly arranged in an inclination direction inclined with respect to a first direction which is a vertical direction, and the anode surface portion And corresponding ones of the cathode surface portions each have a zigzag-shaped portion, and the zigzag-shaped portion has a first inclined surface and a second inclined surface that are connected to each other and is perpendicular to the inclination direction. While projecting in the direction of 2 and extending in the inclined direction, and in the second direction while being recessed in the valleys between the adjacent ones of the first inclined surface and the second inclined surface to extend in the inclined direction It has a recess which is a groove exhibiting the tilt direction and the second constant width in a third direction perpendicular to the direction together, the protrusion及beauty the recess, adjacent to each other corresponding ones of them in to chosen condition, prior SL is disposed in the third direction, the distance between the anode surface and the cathode surface portions, preparing a molten salt electrolysis apparatus Ru der 5mm or more or less 1 mm, the electrode Electrolytically generated gas is generated at the anode surface portion, and an electrolytic process in which an electrolytically generated metal having a specific gravity greater than that of the pre-molten salt is generated at the cathode surface portion corresponding to the anode surface portion, and correspondence between the electrolytically generated gas and the electrolytically generated metal And a step of moving along the concave portion while collecting what is to be collected in the concave portion along the convex portion.

According to the molten salt electrolysis apparatus in the first aspect of the present invention, each of the anode surface portion and the cathode surface portion is inclined and arranged in an inclination direction inclined with respect to the first direction which is the vertical direction, and the anode surface portion and the cathode surface portion. Each of the correspondingly facing parts has a zigzag shaped portion. Here, the zigzag-shaped portion has a first inclined surface and a second inclined surface that are continuous with each other, and protrudes in a second direction perpendicular to the inclined direction and extends in the inclined direction, and the first In the third direction, the first inclined surface and the second inclined surface in the direction 2 are extended in the inclined direction while being recessed at the valleys between adjacent ones of the second inclined surface and in the third direction perpendicular to the inclined direction and the second direction. It has the recessed part which is a groove part which exhibits a fixed width. And these convex parts and concave parts are arrange | positioned in the 3rd direction in the state which connected the corresponding ones of them adjacently, and the distance between an anode surface part and a cathode surface part is 1 mm or more and 5 mm or less It is what is.

  Due to the zigzag shape portion, the electrolysis gas generated on the anode surface portion side can be collected in the concave portion of the zigzag shape portion on the anode surface portion, and the electrolysis metal that is a molten metal generated on the cathode surface portion side is It can gather in the recess of the zigzag shaped part. Here, the concave portion of the zigzag shape portion of the anode surface portion faces the convex portion of the zigzag shape portion of the cathode surface portion, and the concave portion of the zigzag shape portion of the cathode surface portion faces the convex portion of the zigzag shape portion of the anode surface portion. The ascending path of the electrogenerated gas and the flowing down path of the electrolyzed metal can be largely separated. For this reason, the recombination probability between the electrolysis gas and the electrolysis metal can be reduced, and the reverse reaction between them can be suppressed.

At the same time, when the electrolytically generated gas collects in the valleys of the concave portions of the zigzag-shaped portion of the anode surface portion, the electrolytically generated gas is easily united, and the rising rate of the combined electrolytic gas can be increased. As described above, when the rising rate of the electrolysis gas increases, the residence time of the electrolysis gas between the anode surface portion and the cathode surface portion is shortened, the volume occupancy of the electrolysis gas can be reduced, and the overvoltage during electrolysis can be reduced. Can be suppressed.

At the same time, since there is a space for the electrolytically generated metal to enter the valley of the concave portion of the zigzag shaped portion of the cathode surface portion, it is possible to suppress a short circuit due to the presence of the electrolytically generated metal between the narrow anode surface portion and the cathode surface portion. . Further, when the electrolytically generated metal collects in the valleys of the concave portions of the zigzag-shaped portion of the cathode surface portion, the electrolytically generated metal is easily united, and the flow rate of the combined electrolytically generated metal can be increased. As described above, when the flow rate of the electrolytically generated metal is increased, the residence time of the electrolytically generated metal between the anode surface portion and the cathode surface portion is shortened, and a short circuit during electrolysis can be more reliably suppressed. Such an effect on the cathode surface side becomes more remarkable in a system in which the specific gravity of the electrolytically generated metal is larger than that of the molten salt because the electrolytically generated metal surely sinks in the molten salt. Further, the effect on the anode surface portion side and the effect on the cathode surface portion side lead to improvement of the power source unit during electrolysis. Furthermore, since the concave portion is a groove, it is difficult for the electrolytic solution, which is a molten salt, to enter the groove, and the electrolytically generated gas and the electrolytically generated metal are reliably taken into the groove so as not to be diffused unnecessarily. be able to. Furthermore, the distance between the anode surface portion and the cathode surface portion is 1 mm or more and 5 mm or less, so that the distance between the anode surface portion and the cathode surface portion is narrowed to suppress heat generation due to the liquid resistance of the electrolyte that is a molten salt. The required voltage during electrolysis can be greatly reduced, and the power consumption can be greatly improved.

  According to the molten salt electrolysis apparatus in the second aspect of the present invention, the inclination angles of the zigzag-shaped portions of the anode surface portion and the cathode surface portion are each set within a range of 10 degrees to 50 degrees, and the zigzag of the zigzag-shaped section The angles are set in the range of 5 degrees or more and 45 degrees or less, respectively.

  In this way, by setting the inclination angle of the zigzag-shaped portion to 10 degrees or more, it is possible to reliably start raising the electrolysis gas along the corresponding recess, and to cope with the electrolysis metal. It is possible to reliably start to flow down along the recess. On the other hand, by setting the inclination angle of the zigzag-shaped portion to 50 degrees or less, it is possible to maintain the necessary rising speed along the corresponding concave portion in the electrolysis gas and to cope with the electrolysis metal. The necessary flow velocity along the recess to be maintained can be maintained. That is, by setting the inclination angles of the zigzag-shaped portions of the anode surface portion and the cathode surface portion within the range of 10 degrees or more and 50 degrees or less, between the anode surface portion and the cathode surface portion, the electrolytically generated gas or the electrolytically generated metal The electrolysis current efficiency can be improved by keeping the dwell time short while achieving the necessary movement.

  Further, by setting the zigzag angle of the zigzag-shaped portion to 5 degrees or more, it is possible to reliably start collecting the electrogenerated gas in the concave portion and to reliably start collecting the electrogenerated metal in the concave portion. . On the other hand, by setting the zigzag angles of the zigzag-shaped portions to 45 degrees or less, the volume in the recesses can be ensured as required without reducing the volume of the electrolytically generated gas relative to the recesses. A large amount can be collected, and a relatively large amount of electrolytically generated metal can be reliably collected in the recess. That is, the zigzag angle of the zigzag-shaped portion is set in the range of 5 degrees or more and 45 degrees or less, so that the electrolysis gas and the electrolysis metal are reliably concentrated between the anode surface portion and the cathode surface portion. And the amount collected can be relatively large.

According to the molten salt electrolysis apparatus in the third aspect of the present invention, by setting the groove width of the recess to 0.5 mm or more, it is possible to reliably take in the electrolysis gas and the electrolysis metal. In addition, by setting the total width of the grooves to 20% or less of the width of the corresponding anode or cathode, the width of the groove that tends to be inferior in function as an electrode surface portion is limited, and the effective electrolytic area is unnecessary. Reduction can be suppressed.

According to the molten salt electrolysis apparatus in the fourth aspect of the present invention, the width of the groove on each surface of the anode surface portion and the cathode surface portion is kept small by expanding the width of the groove in the depth direction. Therefore, the volume of the electrolytically generated gas and the electrolytically generated metal entering the groove can be increased while suppressing an unnecessary decrease in the effective electrolytic area, and the overvoltage suppressing effect and the short circuit suppressing effect can be enhanced.

  According to the molten salt electrolysis apparatus in the fifth aspect of the present invention, the groove that is the concave portion of the anode surface portion has a branch groove or a protrusion at the bottom in the depth direction thereof, so that the electrolytic solution that is the molten salt is Since it is more difficult to enter the inside of the branch groove or between the protrusions, the overvoltage suppression effect and the short-circuit suppression effect are further enhanced while maintaining the volume of the electrolytically generated gas and electrolytically generated metal that can enter the groove. Can do.

  According to the molten salt electrolysis apparatus in the sixth aspect of the present invention, the molten salt electrolysis apparatus surrounds the periphery of the upper end portion of the groove and is provided with a discharge pipe that opens on the liquid surface of the molten salt, so The generated electrolysis gas escapes to the space above the liquid surface of the molten salt in a series of gas flows, so that the resistance received when the electrolysis gas escapes from the molten salt can be reduced, and the residence time of the electrolysis gas can be reduced. The generation of overvoltage can be more reliably suppressed by reducing the size.

  According to the molten salt electrolyzer in the seventh aspect of the present invention, the material of the discharge pipe is any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz, so that the discharge pipe is in the molten salt. It can exhibit high corrosion resistance even in a severe corrosive environment, and since such a material is an insulator, it has an unnecessary influence on the current flow during electrolysis. You can eliminate that.

  According to the molten salt electrolyzer in the eighth aspect of the present invention, the anode surface portion and the cathode surface portion are parallel to each other, and an electrolytic reaction space is defined between them, so that a simple and stable configuration is achieved. In an easy-to-use apparatus mode, the molten salt can be reliably electrolyzed with high current efficiency.

According to the molten salt electrolyzer in the ninth aspect of the present invention, the outer periphery of the anode and the cathode is further provided with an insulating sheath that covers the entire outer surface except for the upper and lower portions of the electrolytic reaction space, thereby eliminating the need for an electrolytic reaction. Leakage current can be suppressed, and even when the molten salt is in a severe corrosive environment, the molten salt can be reliably electrolyzed while the anode and cathode are reliably protected.

According to the molten salt electrolyzer in the tenth aspect of the present invention, the material of the insulating sheath is any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz, so that the electrode unit is in the molten salt. Even in a severe corrosive environment, it can exhibit high corrosion resistance, and since this material is an insulator, it reliably suppresses unnecessary leakage current during the electrolytic reaction. be able to.

According to the molten salt electrolyzer in the eleventh aspect of the present invention, even when the molten salt contains any of sodium chloride, potassium chloride, lithium chloride, calcium chloride, aluminum chloride, magnesium chloride, and zinc chloride. The molten salt can be reliably electrolyzed while extracting the electrolytically generated gas above the electrode unit and extracting the electrolytically generated metal below the electrode unit.

According to the molten salt electrolysis apparatus in the twelfth aspect of the present invention, the molten salt is a single salt system containing zinc chloride, so that chlorine gas is reliably collected without adopting a mixed salt system as the molten salt. However, the molten salt can be reliably electrolyzed while being drawn out above the electrode unit and collecting the molten zinc exhibiting a specific gravity much heavier than the molten zinc chloride more reliably and drawing it below the electrode unit.

FIG. 1 is a schematic longitudinal sectional view of a molten salt electrolysis apparatus in an embodiment of the present invention. FIG. 2A is a top view of the molten salt electrolysis apparatus according to this embodiment as viewed from the negative side of the z-axis, and FIG. 2B is a front view of the negative electrode as viewed in the positive direction of the x-axis. FIG. Fig.3 (a) is the side view which looked at the cathode of the molten salt electrolysis apparatus in this embodiment in the positive direction of the y-axis, and FIG.3 (b) is AA sectional drawing of Fig.2 (a). 2B is a cross-sectional view taken along line A′-A ′ of FIG. 2B, and FIG. 3C is a cross-sectional view taken along line BB of FIG. 2A and is taken along line B′-B ′ of FIG. It is sectional drawing. 4A is a cross-sectional view taken along the line CC of FIG. 3A, and FIG. 4B is a partially enlarged view of FIG. FIG. 5 is a vertical cross-sectional view of the anode of the molten salt electrolysis apparatus in the present embodiment, and shows the same cross-sectional aspect as FIG. FIG. 6A is a longitudinal sectional view of the first intermediate electrode of the molten salt electrolysis apparatus in the present embodiment, and shows a cross-sectional aspect similar to FIG. 3B shown for the cathode, and FIG. These are DD sectional drawings of Drawing 6 (a). 7 (a) to 7 (d) are partial enlarged oblique sectional views of the anode of the molten salt electrolysis apparatus in the modified example of the present embodiment or another modified example, respectively, and FIG. ) In the same oblique section mode. FIG. 8A is a longitudinal sectional view of the cathode of the molten salt electrolysis apparatus in another modification of the present embodiment, and corresponds to FIG. 3B in position, and FIG. It is a longitudinal cross-sectional view of a cathode, and corresponds to FIG.3 (c) in position.

  Hereinafter, a molten salt electrolysis apparatus and method according to embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the figure, the x, y, and z axes form a triaxial orthogonal coordinate system, and the z direction is the vertical direction and corresponds to the vertical direction.

  FIG. 1 is a schematic longitudinal sectional view of a molten salt electrolysis apparatus in the present embodiment.

  As shown in FIG. 1, the molten salt electrolysis apparatus S has a basic configuration in which a molten salt 20 as an electrolytic solution can be accommodated in an electrolytic cell 10 and an electrode unit U can be immersed in the molten salt 20. .

Specifically, the molten salt 20 is a single salt system typically made of molten metal chloride, which is molten zinc chloride, and the electrolytic cell 10 is heated by an external heater (not shown). When the metal salt is zinc chloride, the metal salt is heated and maintained at a melting point of zinc chloride and a temperature higher than the melting point of zinc. Correspondingly, the electrolytic cell 10 has a material and a structure exhibiting heat resistance and corrosion resistance sufficient to accommodate the high-temperature molten salt 20. In addition to the zinc chloride applicable to the zinc reduction method which is one of the manufacturing methods of the solar cell polysilicon, the molten salt 20 is fundamental in demonstrating the function of the molten salt electrolysis apparatus S. In this case, sodium chloride, potassium chloride, lithium chloride, calcium chloride, aluminum chloride and magnesium chloride can be used. In some cases, a mixed salt system in which a second component is further added may be used.

  The electrode unit U includes an anode 30 and a cathode 40 facing the anode 30 in the x-axis direction, and a first intermediate electrode 50 disposed adjacent to and opposed to each other in the x-axis direction between the anode 30 and the cathode 40. And a second intermediate electrode 60. The electrode unit U may further include an insulating sheath 70 that substantially entirely covers the outer periphery of the anode 30, the cathode 40, the first intermediate electrode 50, and the second intermediate electrode 60. The anode 30, cathode 40, first intermediate electrode 50, and second intermediate electrode 60 are dimensionally stable electrodes called DSE (Dimensionally Stable Electrode), and preferably contain 90% by weight or more of graphite. The material of the insulating sheath 70 is preferably any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz. Note that the number of intermediate electrodes such as the first intermediate electrode 50 and the second intermediate electrode 60 is arbitrary, and in some cases, the number is zero, that is, the intermediate electrode may not be provided.

  The anode 30 and the cathode 40 are typically trapezoidal in the longitudinal section, and are disposed in the molten salt 20 with the top and bottom reversed, and the anode 30 and the cathode 40 include electrode rods 80a and 80b. Are connected correspondingly to supply electrolytic current. The anode 30 has an anode surface portion 30a on the positive side of the x-axis, and the anode surface portion 30a forms an inclined surface or the like that faces downward in the longitudinal section. On the other hand, the cathode 40 has a cathode surface portion 40b on the negative side of the x-axis, and the cathode surface portion 40b forms an inclined surface or the like that faces upward in the longitudinal section. The anode surface portion 30a and the cathode surface portion 40b have substantially the same surface area, are parallel to each other, and face each other at a predetermined interval. Here, when the intermediate electrodes such as the first intermediate electrode 50 and the second intermediate electrode 60 are not provided, the anode surface portion 30a and the cathode surface portion 40b are directly opposed to each other and their corresponding cathodes. A zigzag-shaped portion ZG that defines an electrolytic reaction space between the surface portion and the anode surface portion and functions as an electrode surface portion is provided.

  Here, the cathode 40 will be described in detail with reference to FIGS.

  FIG. 2A is a top view of the molten salt electrolysis apparatus according to this embodiment as viewed from the negative side of the z-axis, and FIG. 2B is a front view of the negative electrode as viewed in the positive direction of the x-axis. FIG. FIG. 3A is a side view of the cathode as viewed in the positive direction of the y-axis, and FIG. 3B is a cross-sectional view taken along the line AA in FIG. It is A'-A 'sectional drawing, FIG.3 (c) is BB sectional drawing of Fig.2 (a), and B'-B' sectional drawing of FIG.2 (b). 4A is a sectional view taken along the line CC in FIG. 3A, and FIG. 4B is a partially enlarged view of FIG. 4A.

As shown in more detail in FIGS. 2 to 4, the cathode 40 includes a first inclined surface 42 a and a second inclined surface 42 b that are continuous with each other, and the first inclined surface 42 a and the second inclined surface 42 with respect to the z axis. A convex portion 42 projecting in the direction opposite to the x ′ direction (which is the positive direction of the x axis and the negative direction of the z axis) perpendicular to the inclination direction of the two inclined surfaces 42b; A recess 44 having a certain depth and recessed in the x ′ direction is connected to each other while adjoining each other in the y-axis direction, thereby forming a cathode surface portion 40b which is a zigzag-shaped portion ZG. . In one convex portion 42, the connecting portion of the first inclined surface 42a and the second inclined surface 42b extends upward with a positive inclination in the xz plane between the upper surface 40c and the lower surface 40d of the cathode 40. The first inclined surface 42a and the second inclined surface 42b are adjacent to each other and have the same inclination as the ridge between the upper surface 40c and the lower surface 40d of the cathode 40. against recess 44 extending into, continuous descends with each inclined.

Further, the width of the recess 44, which is the groove, is preferably set to 0.5 mm or more in order to reliably take in the electrolytically generated metal therein. In addition, the total width of the concave portions 44 as the groove portions is limited by the width of the cathode 40 in order to limit the width of the groove portions that tend to be inferior in function as the cathode surface portion, and to secure a necessary and sufficient effective electrolysis area. It is preferable to set it to 20% or less.

  At both end portions 42t, 42t in the y-axis direction of the cathode 40, the convex portion 42 does not have to include both the first inclined surface 42a and the second inclined surface 42b. At the positive end 42t, the convex 42 has only the second inclined surface 42b, and at the negative end 42t in the y-axis direction, the convex 42 has only the first inclined surface 42a. A configuration example is shown. The cathode surface part 40b which is the zigzag-shaped part ZG is configured to include a required number of convex parts 42 and concave parts 44. In the minimum structural unit of the convex portion 42 and the concave portion 44, a configuration including one convex portion 42 and two concave portions 44 that are adjacent to each other, or one concave portion 44 and two adjacent to each other. The structure provided with the convex part 42 is mentioned. The convex portion 42 has only the second inclined surface 42b at the positive end 42t in the y-axis direction, and only the first inclined surface 42a at the negative end 42t in the y-axis direction. You may have. The recess 44 may be disposed adjacent to the positive end 42t in the y-axis direction and the negative end 42t in the y-axis direction. Further, the first inclined surface 42a and the second inclined surface 42b may have a curved surface shape as well as a planar shape.

  The concave portions 44 are continuous with the cutout portions 46 at their upper portions. The notch 46 is a notch that has a longitudinal section that is notched so as to project the upper surface 40c of the cathode 40 and extends in the y-axis direction. It is an equilateral right triangle.

  In the cathode 40, the electrolytically generated metal generated at the cathode surface portion 40 b by the electrolysis of the molten salt 20 flows along the first inclined surface 42 a and the second inclined surface 42 b of the convex portion 42 in the molten salt 20. , They gather together in the corresponding recesses 44, and the collected electrogenerated metals coalesce and flow down along the corresponding recesses 44, and further flow down over the lower surface 40d of the cathode 40, and more It is stored in the molten salt 20 at the bottom of the lower electrolytic cell 10. Further, even if the electrolytically generated metal generated near the upper end of the cathode surface portion 40b moves upward accompanying the rising electrolytically generated gas, the electrolytically generated metal is not separated from the first inclined surface 42a and the second inclined surface 42a. Since the inclined surface 42b flows into the notch 46 in the adjacent portion, it is unnecessarily diffused or accumulated in the cathode surface portion 40b toward the electrolytic reaction space defined between the cathode surface portion 40b and the corresponding anode surface portion. It is possible to flow down along the recess 44 continuous with the notch 46 without any problem. That is, the notch 46 functions as an introduction part that collects the electrolytically generated metal existing at the upper part of the cathode 40 and guides it to the recess 44. Further, the notch 46 may have an inclined surface that descends toward the recess 44.

  The concave portion 44 has a certain depth and width and is formed as a rectangular groove portion having an oblique cross section, but is not limited to this, and the first inclined surface 42a of the convex portion 42 and Although the certainty of collecting the electrolytically generated metal more reliably along the second inclined surface 42b and sending it downward is somewhat reduced, as shown by the one-dot chain line in FIG. The valley part where the connection part of the 2nd inclined surface 42b was continued may be sufficient. In addition, the notch portion 46 is formed leaving the ridge portions of the corresponding first inclined surface 42a and second inclined surface 42b at both end portions 42t and 42t, but is not limited thereto. Although the barrier function of sending the electrolytically generated metal downward without unnecessarily leaking in the lateral direction is somewhat reduced, it may be formed through both end portions 42t and 42t. Further, when the electrolytically generated metal generated around the upper end of the cathode surface portion 40b and blown up to the upper surface 40c can be ignored, the notched portion 46 may be omitted.

  The anode 30 is different from the cathode 40 in that the posture disposed in the molten salt 20 is opposite and only the related structure of the notch portion and the attachment portion of the electrode rods 80a and 80b is different. Therefore, the anode 30 will be described in detail with reference to FIG. 5 while omitting or simplifying the description and illustration as appropriate.

  FIG. 5 is a vertical cross-sectional view of the anode of the molten salt electrolysis apparatus in the present embodiment, and shows the same cross-sectional aspect as FIG.

As shown in detail in FIG. 5, the anode 30 has a convex portion 32 having a first inclined surface and a second inclined surface that are continuous with each other and projecting in the x ′ direction, and a certain depth. The concave portion 34 that is the groove portion that is provided and that is recessed in the direction opposite to the x ′ direction is connected to be adjacent to each other in the y-axis direction, thereby forming the anode surface portion 30a that is the zigzag-shaped portion ZG. In one of the protrusions 32, the connection portion of the first inclined surface and the second inclined surface extends upwardly with a positive slope in the x-z plane between the upper surface 30c and lower surface 30d of the anode 30 forms a ridge, such first inclined surface and the second inclined surface, they extend upwardly with the same slope and ridge between the upper surface 30c and lower surface 30d of the anode 30 together with the adjacent The aspect of descending and continuing with respect to the recess 34 while being inclined is the same as that in the cathode 40. The shape of the recess 34 is the same as that of the recess 44 in the cathode 40.

  However, the convex portion 32 in the anode surface portion 30a should be opposed to the concave portion 44 in the cathode surface portion 40b of the cathode 40, and the concave portion 34 in the anode surface portion 30a is opposed to the convex portion 42 in the cathode surface portion 40b of the cathode 40. Therefore, the zigzag-shaped portion ZG in the anode surface portion 30a of the anode 30 is arranged so that the projection phase and the concave portion are disposed in the y-axis direction correspondingly to the zigzag-shaped portion ZG in the cathode surface portion 40b of the cathode 40. Will shift. Correspondingly, the configuration of the zigzag-shaped portion ZG at both ends in the y-axis direction of the anode surface portion 30a of the anode 30 and the convex portion 42 and the concave portion 44 of the zigzag-shaped portion ZG at the cathode surface portion 40b of the cathode 40 are the minimum structural unit. In this case, the configuration of the zigzag-shaped portion ZG in the anode surface portion 30a of the anode 30 is also defined.

  Moreover, it is preferable to set the width | variety of the recessed part 34 which is a groove part to 0.5 mm or more, in order to take in electrolysis production gas there reliably. In addition, the total width of the recesses 34, which are such grooves, is limited by the width of the anode 30 in order to limit the width of the grooves that tend to be inferior in function as the anode surface portion, and to ensure a necessary and sufficient effective electrolytic area. It is preferable to set it to 20% or less.

  In addition, the recess 34 is formed as a rectangular groove portion having a certain depth and width and having an oblique cross section. However, the present invention is not limited to this, and similarly to the recess 44 in the cathode surface portion 40b, The valley part which the connection part of the 1st inclined surface and the 2nd inclined surface continued may be sufficient. In addition, a notch such as the notch 46 provided in the cathode 40 does not need to be provided in the anode 30 in terms of function.

  In the anode 30, the electrolysis gas generated in the anode surface portion 30 a by electrolysis of the molten salt 20 is along the first inclined surface 32 a and the second inclined surface 32 b of the convex portion 32 in the molten salt 20. The collected electrolysis gas gathers in the corresponding recesses 34, rises along the corresponding recesses 34 while uniting the bubbles, and rises over the upper surface 30c of the anode 30, The molten salt 20 is discharged outward from the liquid surface 20a. In addition, the 1st inclined surface 32a and the 2nd inclined surface 32b are illustrated in FIG. 7 for convenience.

  The first intermediate electrode 50 and the second intermediate electrode 60 have the same configuration having anode surface portions 50a and 60a and cathode surface portions 50b and 60b similar to the anode 30 and the cathode 40, respectively, and in the same posture, the molten salt The first intermediate electrode 50 is typically arranged in the shape of a rhombus with a vertical cross section, and the first intermediate electrode 50 is further referred to with reference to FIG. The details will be described representatively.

FIG. 6A is a longitudinal sectional view of the first intermediate electrode of the molten salt electrolysis apparatus in the present embodiment, and shows a cross-sectional aspect similar to FIG. 3B shown for the cathode, and FIG. These are DD sectional drawings of Drawing 6 (a).

As shown in more detail in FIG. 6, the first intermediate electrode 50 has a first inclined surface and a second inclined surface that are continuous with each other and protruded in a direction opposite to the x ′ direction. 52 and a concave portion 54 having a certain depth and width and having a rectangular cross-section and a rectangular shape, and is recessed in the x ′ direction, are connected to each other in the y-axis direction, A cathode surface portion 50b which is a zigzag shape portion ZG is formed. The cathode surface portion 50 b has the same configuration as that of the cathode surface portion 40 b in the cathode 40, and the connection portion between the first inclined surface and the second inclined surface is the upper surface of the first intermediate electrode 50 in one convex portion 52. It forms a ridge extending upwardly 50c and has a positive slope in the x-z plane between the lower surface 50d, according a first inclined surface and the second inclined surface, first with their adjacent Between the upper surface 50c and the lower surface 50d of the intermediate electrode 50, the recesses 54 extending upward with the same inclination as the ridges are respectively lowered and connected. Further, the convex part 52 and the concave part 54 are continuous with the notch part 56 at the upper part thereof. Such an aspect is the same as that in the cathode 40.

Further, the first intermediate electrode 50 has a convex portion 52 ′ having a first inclined surface and a second inclined surface continuous with each other and protruding in the x ′ direction, and has a certain depth and width. Then, the recess 54 ′, which is a rectangular groove portion having an oblique cross section and is recessed in the direction opposite to the x ′ direction, is connected while adjoining each other in the y axis direction, so that the anode which is the zigzag shape portion ZG A surface portion 50a is configured. The anode surface portion 50 a has the same configuration as that of the anode surface portion 30 a in the anode 30, and the connecting portion of the first inclined surface and the second inclined surface is connected to the first intermediate electrode 50 in one convex portion 52 ′. A ridge extending upward with a positive inclination in the xz plane is formed between the upper surface 50c and the lower surface 50d, and the first inclined surface and the second inclined surface are adjacent to each other and are adjacent to each other. against recess 54 'that extends upward with the same slope and ridge portion between the first top surface 50c and bottom surface 50d of the intermediate electrode 50, continuing to descend with each inclined. This aspect is the same as that in the anode 30.

  Here, the cathode surface portion 50b of the first intermediate electrode 50 is parallel to the anode surface portion 30a of the anode 30 and faces the anode surface portion 30a at a predetermined interval, and defines an electrolytic reaction space with the anode surface portion 30a. The anode surface portion 50a of the first intermediate electrode 50 is parallel to the cathode surface portion 60b of the second intermediate electrode 60 and is opposed to the cathode surface portion 60b by a predetermined distance to define an electrolytic reaction space. The anode surface portion 60a of the second intermediate electrode 60 is parallel to the cathode surface portion 40b of the cathode 40 and is opposed to the cathode surface portion 40b at a predetermined interval, and defines an electrolytic reaction space between the cathode surface portion 40b.

  In the first intermediate electrode 50, the electrolysis gas generated in the anode surface portion 50 a by the electrolysis of the molten salt 20 corresponds to the first inclined surface and the second of the convex portion 52 ′ in the molten salt 20. Along the inclined surfaces of the first and second recesses 54 ′, which correspond to each other, gather in the corresponding recesses 54 ′. The intermediate electrode 50 rises over the upper surface 50c and is discharged outward from the liquid surface 20a of the molten salt 20. On the other hand, the electrolysis-generated metal produced | generated by the cathode surface part 50b by electrolysis of the molten salt 20 flows along the 1st inclined surface and 2nd inclined surface of the convex part 52 in molten salt 20, and they respond | correspond Then, the electrogenerated metal collected in this way flows down along the corresponding concave portion 54 and further flows down over the lower surface 50d of the first intermediate electrode 50, so that the lower electrolytic cell 10 In the molten salt 20 at the bottom.

  Similarly, in the second intermediate electrode 60, the electrolysis gas generated at the anode surface portion 60 a by the electrolysis of the molten salt 20 rises while gathering and rises over the upper surface 60 c, and the liquid of the molten salt 20 Released outward from the surface 20a. On the other hand, the electrolyzed metal produced in the cathode surface portion 60b by the electrolysis of the molten salt 20 flows down while collecting, flows down over the lower surface 60d, and accumulates in the molten salt 20 at the bottom of the lower electrolytic cell 10. It is done.

  Here, the anode surface portion 30 a of the anode 30, the anode surface portion 50 a of the first intermediate electrode 50 and the anode surface portion 60 a of the second intermediate electrode 60, the cathode surface portion 40 b of the cathode 40, and the cathode surface portion 50 b of the first intermediate electrode 50. In addition, the inclination angle (angle with respect to the z axis) α of the zigzag-shaped portion ZG in the cathode surface portion 60b of the second intermediate electrode 60 is preferably in the range of 10 degrees to 50 degrees. Such an inclination angle α is representatively shown in the anode surface portion 30a of the anode 30 in FIG.

  This is because when the inclination angle α of the zigzag-shaped portion ZG is set to 10 degrees or more, the electrolysis gas can be reliably started to rise along the corresponding recess, and This is because it can be reliably started to flow down along the corresponding concave portion. At the same time, by setting the inclination angle α of the zigzag-shaped portion ZG to 50 degrees or less, it is possible to maintain the necessary rising speed along the corresponding concave portion in the electrolysis generated gas, and the electrolysis metal This is because it is possible to maintain the necessary flow velocity along the corresponding recess in the case. That is, when the inclination angle α of the zigzag-shaped portion ZG of the anode surface portion and the cathode surface portion is set within a range of 10 degrees or more and 50 degrees or less, electrolytic generation is generated between the anode surface section and the cathode surface section corresponding to each other. This is because it is possible to achieve good electrolysis current efficiency by keeping the residence time short while achieving the necessary movement of the gas and the electrolytically generated metal.

  Also, the zigzag angle (angle with respect to the y axis in the oblique section) β formed by the first inclined surfaces 32a, 42a, etc. and the second inclined surfaces 32b, etc. 42b in the anode surface portion 30a, the cathode surface portion 40b, etc. is 5 It is preferable that it is in the range of not less than 45 degrees and not more than 45 degrees. The zigzag angle β is representatively shown in FIGS. 4 (a) and 6 (b).

  This is because the zigzag angle β of the zigzag-shaped portion ZG is set to 5 degrees or more, respectively, so that it is possible to reliably start collecting the electrogenerated gas in the corresponding recess, and the corresponding recess in the electrogenerated metal. It is because it can start collecting surely. In addition, the zigzag angle β of the zigzag shaped portion ZG is set to 45 degrees or less, respectively, so that the volume in the corresponding concave portion can be secured to the required volume without excessively narrowing, and the electrogenerated gas can be reduced. This is because it is possible to reliably collect a relatively large amount in the corresponding concave portion and to reliably collect a relatively large amount of the electrolytically generated metal in the corresponding concave portion. That is, the zigzag angle β of the zigzag shaped portion ZG is set in the range of 5 degrees or more and 45 degrees or less, so that the electrolysis gas and the electrolysis metal are reliably concentrated between the anode surface portion and the cathode surface portion. This is because the amount collected can be relatively large.

  Referring again to FIG. 1, the insulation sheath 70 covers the entire outer periphery of the anode 30, the cathode 40, the first intermediate electrode 50, and the second intermediate electrode 60. Electrolytic reaction space defined between them, the upper end of the recess in the zigzag-shaped portion ZG of the anode surface portion of these electrodes, and the lower end of the recess in the zigzag-shaped portion ZG of the cathode surface portion of these electrodes An upper opening 70a and a lower opening 70b each having a shape are provided.

Specifically, the upper opening 70 a and the lower opening 70 b are the electrolytic reaction space defined between the anode surface portion 30 a of the anode 30 and the cathode surface portion 50 b of the first intermediate electrode 50, the first intermediate electrode 50. An electrolytic reaction space defined between the anode surface portion 50a of the second intermediate electrode 60 and the cathode surface portion 60b of the second intermediate electrode 60, and a space between the anode surface portion 60a of the second intermediate electrode 60 and the cathode surface portion 40b of the cathode 40. The upper opening 70a is disposed corresponding to the upper part of these electrolytic reaction spaces, while the lower opening 70b is provided below the electrolytic reaction spaces. Correspondingly arranged. The electrolysis gas generated by the electrolysis of the molten salt 20 at the anode surface portions 30a, 50a, and 60a and rising together is discharged to the outside of the electrode unit U through the upper openings 70a and rises, and the molten salt 20 liquid Released outward from the surface 20a. On the other hand,
Electrolytically generated metals that are generated in the cathode surface portions 40b, 50b, and 60b by the electrolysis of the molten salt 20 and flow down together are discharged to the outside of the electrode unit U through the lower openings 70b and flow down, respectively. In the molten salt 20 at the bottom.

  The zigzag-shaped portion ZG described above includes the anode surface portion 30a of the anode 30, the anode surface portion 50a of the first intermediate electrode 50, the anode surface portion 60a of the second intermediate electrode 60, the cathode surface portion 40b of the cathode 40, and the first. The intermediate electrode 50 may be selectively provided not only on the cathode surface portion 50b of the intermediate electrode 50 and the cathode surface portion 60b of the second intermediate electrode 60 but on any of them.

  Next, an electrolysis method for electrolyzing the molten salt using the molten salt electrolysis apparatus S having the above configuration will be described in detail. The series of steps of the electrolysis method may be automatically controlled by a controller having various databases while referring to detection data from various sensors, or part or all of the steps may be performed manually.

  First, the electrode unit U is disposed and fixed in the electrolytic cell 10 at a predetermined position, and the molten salt 20 is filled up to a predetermined liquid level so as to completely sink the electrode unit U. The molten salt 20 has a large specific gravity difference between the molten metal and the molten metal chloride in each molten state, and can be easily and reliably separated from the flow of the electrogenerated metal and the flow of the electrogenerated gas. Zinc was used.

  Next, an electrolytic current starts to flow between the anode 30 and the cathode 40 through the electrode rods 80a and 80b.

  Then, in the anode 30, the electrolysis gas is generated in the anode surface portion 30 a by electrolysis of the molten salt 20 in the electrolytic reaction space defined between the anode surface portion 30 a of the anode 30 and the cathode surface portion 50 b of the first intermediate electrode 50. The electrolytically generated gas generated in this way is in the molten salt 20 along the first inclined surface 32a and the second inclined surface 32b of the convex portion 32, and the concave portion 34 in which they correspond to each other. The electrolytically generated gas collected in this manner rises along the corresponding concave portion 34, passes through the upper surface 30 c of the anode 30, and is discharged out of the electrode unit U through the upper opening 70 a of the insulating sheath 70. It rises and is discharged outward from the liquid surface 20a of the molten salt 20. This phenomenon is the same in the anode surface portion 50a of the first intermediate electrode 50 and the anode surface portion 60a of the second intermediate electrode 60.

  At the same time, in the cathode 40, the electrolyzed metal is produced at the cathode surface portion 40 b by electrolysis of the molten salt 20 in the electrolytic reaction space defined between the anode surface portion 60 a of the second intermediate electrode 60 and the cathode surface portion 40 b of the cathode 40. Is generated. The electrolytically generated metal thus generated flows in the molten salt 20 along the first inclined surface 42a and the second inclined surface 42b of the convex portion 42, and gathers in the concave portion 44 where they correspond to each other, The electrolytically generated metal collected in this way flows down along the corresponding concave portion 44, passes through the lower surface 40 d of the cathode 40, is discharged out of the electrode unit U through the lower opening 70 b of the insulating sheath 70, and further flows down. And is stored in the molten salt 20 at the bottom of the lower electrolytic cell 10. This phenomenon is the same in the cathode surface portion 50 b of the first intermediate electrode 50 and the cathode surface portion 60 b of the second intermediate electrode 60.

  Then, when a predetermined electrolysis time has elapsed, the electrolysis current flowing between the anode 30 and the cathode 40 via the electrode rods 80a and 80b is stopped, and the current series of steps is completed. As a result of such a series of steps, an electrolysis product gas is obtained above the molten salt 20, and an electrolysis product metal is obtained at the bottom of the electrolytic cell 10.

Next, each modification of the electrode unit U in the molten salt electrolysis apparatus S in the present embodiment will be described in detail with reference to the drawings as appropriate. Each of the modified examples is the same as the configuration of the above-described embodiment except for the configuration specifically described, and therefore the description, illustration, and the like are appropriately omitted or simplified.

  7 (a) to 7 (d) are partial enlarged oblique sectional views of the anode of the molten salt electrolysis apparatus in each modification of the present embodiment, and are the same as FIG. 4 (b) shown for the cathode. It is shown in an oblique section.

  In the modification shown in FIG. 7A, the recess 34 itself of the anode 130 has the same configuration as that shown in FIG. 5, but a plurality of branch grooves 34a and 34b extending radially in the deepest part. , 34c. In addition, as shown in FIG. 1, a discharge pipe P is connected to the recess 34 having the branch grooves 34a, 34b, and 34c so as to surround them. The discharge pipe P is attached to the anode 130 through the recess 134 having the branch grooves 34a, 34b, and 34c as described above, and is opened above the liquid surface 20a of the molten salt 20. The material of the discharge pipe P is preferably any of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz. Moreover, this discharge pipe P is applicable also to the anode 30 which has the recessed part 34 without a branching groove | channel shown in FIG. In addition, the discharge pipe P is shown with a dashed-dotted line in the figure.

  In another modification shown in FIG. 7B, the concave portion 134 of the anode 230 has the same width in the y-axis direction at the opening end portion as that of the concave portion 34 of the anodes 30 and 130, but the depth thereof. It has a longitudinal cross-sectional shape that is widened in the direction. Similarly, in this other modification, the discharge pipe P is connected to the recess 34 so as to surround the recess 34.

  In another modification shown in FIG. 7C, the concave portion 134 of the anode 330 has a longitudinal cross-sectional shape that is gradually widened in the depth direction, and extends in the radial direction at the deepest portion. It has a plurality of branch grooves 134a, 134b, 134c. Similarly, in this modification, the discharge pipe P is connected to the recess 134 having the plurality of branch grooves 134a, 134b, and 134c so as to surround it.

  In the modification shown in FIG. 7D, the recess 34 itself of the anode 430 is the same as the configuration shown in FIGS. 5 and 7A, but a plurality of protrusions projecting in the x ′ direction from the deepest part. Projections 34a ', 34b', 34c '. Similarly, in this other modification, the discharge pipe P is connected to the recess 34 having the plurality of protrusions 34a ', 34b', 34c 'so as to surround it.

  In the configuration of each comparative example having the above configuration, electrolysis gas is generated in the anode surface portion 30 a by electrolysis of the molten salt 20, and the electrolysis gas generated in this way is the convex portion 32 in the molten salt 20. A concave portion 34 having a branch groove 34a, 34b, 34c, and a concave portion 134, and a concave portion 134 having a branch groove 134a, 134b, 134c that correspond to each other along the first inclined surface 32a and the second inclined surface 32b. The electrolysis gas collected in this manner rises along the recess 34 having the corresponding branch groove 34a, 34b, 34c, the recess 134 and the recess 134 having the branch grooves 134a, 134b, 134c, The upper surface 30c of the anode 30 is passed through the upper opening 70a of the insulating sheath 70 to reach the inside of the discharge pipe P. It is released to the outside from.

Here, since the concave portion 34 of the anode 130 in the modification shown in FIG. 7A has branch grooves 34a, 34b, and 34c, the electrolytically generated gas is more reliably introduced into the branch grooves 34a, 34b, and 34c. The molten salt 20 is not easily penetrated into the branch grooves 34a, 34b, and 34c, and the gas-liquid in the branch grooves 34a, 34b, and 34c is a factor that reduces the rising rate of the electrolysis gas. The mixed state becomes difficult to appear. The recess 134 of the anode 230 in another modification shown in FIG. 7B has a longitudinal cross-sectional shape that is gradually widened in the depth direction, so that the electrolytically generated gas is more reliably recessed. It is raised while staying in 134. In addition, the concave portion 134 of the anode 330 in another modification shown in FIG. 7C has a longitudinal sectional shape that is gradually widened in the depth direction, and in addition to the branch grooves 134a, 134b, and 134c. Therefore, the electrolytically generated gas is further raised while remaining in the recess 134 having the branch grooves 134a, 134b, and 134c. In addition, since the concave portion 34 of the anode 430 in another modification shown in FIG. 7D has projections 34a ′, 34b ′, and 34c ′, the electrolytically generated gas can be more reliably supplied to the projections 34a ′ and 34b ′. , 34c ′, the molten salt 20 is not easily penetrated into the groove, and the gas-liquid mixed state in the groove becomes a factor that reduces the rate of rise of the electrolysis gas. It becomes difficult to put out. Here, the electrolytically generated gas is raised while being more reliably retained in the groove between the protrusions 34a ′, 34b ′, 34c ′, and the molten salt 20 is prevented from entering the groove so as to be in a gas-liquid mixed state. From the standpoint of suppressing the occurrence of this, it is preferable that the total width of the protrusions 34 a ′, 34 b ′, 34 c ′ is set to 30% or less of the width of the anode surface portion 32.

  The configuration of each of the above modifications may be applied to the anode surface portion 50a of the first intermediate electrode 50 and the anode surface portion 60a of the second intermediate electrode 60, as shown in each discharge pipe P in FIG. .

  7B is applied to the cathode surface portion 40b of the cathode 40, the cathode surface portion 50b of the first intermediate electrode 50, and the cathode surface portion 60b of the second intermediate electrode 60. May be.

  FIG. 8A is a longitudinal sectional view of the cathode of the molten salt electrolysis apparatus in another modification of the present embodiment, and corresponds to FIG. 3B in position, and FIG. It is a longitudinal cross-sectional view of a cathode, and corresponds to FIG.3 (c) in position.

  In another modification shown in FIG. 8, the cathode 140 is different from the cathode 40 shown in FIGS. 2 to 4 in that the notched portion 46 is not provided, and the penetrating portion 146 and the penetrating through the closing portion 146 are provided. It has a configuration in which a hole 148 is provided.

  Specifically, the closing portion 146 is a protruding portion that closes the upper portion of the recess 44. The through hole 148 passes through the blocking portion 146 and opens the recess 44 toward the upper surface 40c through the through hole 148.

  In such a modified example, even if the electrolytically generated metal generated in the cathode surface portion 40b or the like by the electrolysis of the molten salt 20 moves upward and stays on the upper surface 40c of the cathode 140, the electrolytically generated metal remains in the through hole. Since it flows into 148, it can flow down along the recess 44 through the through hole 148 without unnecessarily diffusing toward the electrolytic reaction space defined between the cathode surface portion 40b and the corresponding anode surface portion. That is, the through-hole 148 functions as an introduction portion that collects the electrolytically generated metal existing in the upper portion of the cathode 40 and guides it to the recess 44. It is also possible to provide a counterbore part that counters the upper surface 40c around the opening of the through hole 148 in the upper surface 40c. In such a configuration, the electrolytically generated metal staying on the upper surface 40c is easily introduced into the through-hole 148 through the counterbore and flows down downward.

  The configuration of this modification may be applied to the cathode surface portion 40b of the cathode 40, the cathode surface portion 50b of the first intermediate electrode 50, and the cathode surface portion 60b of the second intermediate electrode 60, respectively.

  Next, each experimental example in the present embodiment including various modifications will be described in detail with reference to each comparative example.

As shown in the following (Table 1), in Comparative Examples A and B and Experimental Examples C to E, the electrode unit U includes the anode 30, the cathode 40, the first intermediate electrode 50, and the second intermediate electrode. The anode surface portion 30a of the anode 30 shown as an electrode inclination, the anode surface portion 50a of the first intermediate electrode 50 and the anode surface portion 60a of the second intermediate electrode 60, and the cathode surface portion 40b of the cathode 40, The sizes of the cathode surface portion 50b of the first intermediate electrode 50 and the cathode surface portion 60b of the second intermediate electrode 60 were set to be equal, and the inclination angle α was set to 45 ° C.

In Comparative Examples A and B and Experimental Examples C to E, molten zinc chloride is used as a molten salt 20 in a single salt system, and its temperature is controlled to be kept constant at 550 ° C. The current density was set to a constant value of 0.55 A / cm ² . Since the specific gravity of such molten zinc chloride is greater than the specific gravity of molten zinc, which is an electrolytic product metal, in the electrolytic reaction of molten zinc chloride, the molten zinc, which is an electrolytic product metal, moves downward in the molten zinc chloride, which is an electrolytic solution. It will sink. The anode 30, the cathode 40, the first intermediate electrode 50, and the second intermediate electrode 60 were made of graphite, and the insulating sheath 70 was made of alumina.

  Specifically, in Comparative Example A, the distance between the anode surface portion 30a of the anode 30 and the cathode surface portion 50b of the first intermediate electrode 50, each shown as the electrode interval, and the anode surface portion 50a of the first intermediate electrode 50 and the second surface. The distance between the cathode surface portion 60 b of the intermediate electrode 60 and the distance between the anode surface portion 60 a of the second intermediate electrode 60 and the cathode surface portion 40 b of the cathode 40 is 10 mm, and the anode surface portion 30 a of the anode 30 and the first intermediate electrode 50 The anode surface portion 50a and the anode surface portion 60a of the second intermediate electrode 60, the cathode surface portion 40b of the cathode 40, the cathode surface portion 50b of the first intermediate electrode 50, and the cathode surface portion 60b of the second intermediate electrode 60 have zigzag-shaped portions. ZG is not provided, and correspondingly, the anode surface portion 30a, the anode surface portion 50a and the anode surface portion 60a, and the cathode surface portion 40b, the cathode surface portion 50b and the cathode surface portion 60b are all provided with convex portions 3. It is not provided, and the like, and the concave portion 32 or the like. Further, the comparative example B is different from the comparative example 1 in that the electrode interval is 1 mm, and the other points are the same.

  When Comparative Example B is compared with Comparative Example A, in Comparative Example B, the current efficiency is reduced from 83.0% to 28.1%. This is because when the electrode interval is reduced from 10 mm to 1 mm, the chance of contact between the chlorine gas generated from the anode surface portions 30a, 50a and 60a and the molten zinc generated from the cathode surface portions 40b, 50b and 60b increases. This is thought to be due to an increase in the resulting reverse reaction. Further, as the electrode spacing is reduced from 10 mm to 1 mm in this way, the overvoltage is increased from 0.0 V to 2.5 V. Here, the overvoltage was defined as the difference between the theoretical electrolysis voltage calculated from the solution resistance and decomposition voltage of zinc chloride and the actual electrolysis voltage. That is, it is shown that normal molten salt electrolysis is generally not possible with a small electrode interval of 1 mm.

  In Experimental Example C, compared to Comparative Example B, the anode surface portion 30a of the anode 30, the anode surface portion 50a of the first intermediate electrode 50, the anode surface portion 60a of the second intermediate electrode 60, the cathode surface portion 40b of the cathode 40, the first The difference is that zigzag-shaped portions ZG are respectively provided on the cathode surface portion 50b of the first intermediate electrode 50 and the cathode surface portion 60b of the second intermediate electrode 60, and the other points are the same. The zigzag angle of the zigzag-shaped portion ZG is set to 10 degrees, and the recesses 34, etc., are simply between the first inclined surface 42a, the second inclined surface 42b, etc., which have no grooves. It was set in the valley that intersects.

When the experimental example C is compared with the comparative example B, in the experimental example C, the current efficiency is greatly improved from 28.1% to 48.5%. This is because zigzag-shaped portions are given to all of the anode surface portions 30a, 50a and 60a and the cathode surface portions 40b, 50b and 60b, so that the convex portions 32 and the like of the anode surface portions 30a, 50a and 60a While chlorine gas collects, molten zinc collects from the convex portions 42, etc. of the cathode face portions 40b, 50b, 60b to the concave portions 44, etc., so that the separation effect between chlorine gas and molten zinc is increased and the reverse reaction is suppressed. it is conceivable that. In addition, the overvoltage is also reduced from 2.5V to 1.8V. This is presumably because the chlorine gas escapes faster as it gathers and escapes while gathering in the concave portions 34 of the anode surface portions 30a, 50a, 60a. Together, these events result in an increase in power intensity (power efficiency) for generating zinc from 5.33 kW · hh / kg (Zn) to 3.87 kW · h / kg (Zn). The zigzag-shaped portion ZG is provided on all of the anode surface portions 30a, 50a, 60a and the cathode surface portions 40b, 50b, 60b.

  In Experimental Example D, compared to Experimental Example C, in the cathode surface portion 40b of the cathode 40, the cathode surface portion 50b of the first intermediate electrode 50, and the cathode surface portion 60b of the second intermediate electrode 60, those concave portions 44 and the like are used as groove portions. The difference is that it is configured, and the other points are the same. As shown in FIG. 4, the groove is typically rectangular with an oblique cross section, the width of the groove is 0.5 mm or more, and the sum of them is 20% or less of the width of the cathode surface portion 50b or the like. The predetermined value was set within the range.

  Comparing Experimental Example D with Experimental Example C, the current efficiency is further improved from 48.5% to 61.3%. This is because the recesses 44 and the like of the cathode surface portions 40b, 50b and 60b are configured as grooves, so that the molten zinc is more effectively collected in the recesses 44 and the like which are the groove portions of the cathode surface portions 40b, 50b and 60b. It is thought that the separation effect of gas and molten zinc was further increased and the reverse reaction was suppressed. On the other hand, although the overvoltage is slightly reduced from 1.8 V to 1.7 V, it is almost equal to the value of Experimental Example C. This is presumably because the zigzag-shaped portion ZG of the anode surface portions 30a, 50a, 60a remains a simple valley portion in Experimental Example C, so that the chlorine gas escape itself does not change. These events are combined, and as a result, the power consumption for generating zinc is improved from 3.87 kW · hh / kg (Zn) to 3.09 kW · h / kg (Zn).

  In Experimental Example E, in contrast to Experimental Example D, in the anode surface portion 30a of the anode 30, the anode surface portion 50a of the first intermediate electrode 50, and the anode surface portion 60a of the second intermediate electrode 60, these concave portions 34 and the like are experimental examples. The difference is that it is configured as a groove portion equivalent to the groove portion in C and the discharge pipe P made of alumina is provided to the concave portion 34 and the like, and the other points are the same. The discharge pipe P is set to have a predetermined diameter sufficient to surround the recess 34 or the like that is the groove.

  When the experimental example E is compared with the experimental example D, the current efficiency is further improved from 61.3% to 70.0%. This is because, in addition to the concave portions 34 and the like of the anode surface portions 30a, 50a, and 60a being configured as the groove portions, the discharge pipe P is provided to the concave portions 34 and the like that are the groove portions of the anode surface portions 30a, 50a, and 60a. The rising speed of the chlorine gas increases, and the chlorine gas quickly escapes out of the molten salt 20 from the recesses that are the groove portions of the anode surface portions 30a, 50a, 60a. It is thought that the separation effect of gas and molten zinc was further increased and the reverse reaction was further suppressed. Thus, since the volume of chlorine gas with respect to the volume of molten zinc chloride in the electrolytic reaction space is greatly reduced, the overvoltage is also greatly reduced from 1.7V to 0.5V. Then, these events are combined, and as a result, the power intensity for generating zinc is improved from 3.09 kW · hh / kg (Zn) to 2.24 kW · h / kg (Zn). .

  Further, although not shown in the table, in the configuration of Experimental Example D, the concave portion 34 and the like of the anode surface portions 30a, 50a, and 60a are the groove portions equivalent to the groove portions in Experimental Example C, that is, from the configuration of Experimental Example E. When comparing the experimental examples with the discharge pipe P omitted with respect to the experimental examples E and D, the current efficiency and overvoltage did not reach the level of the experimental example E, but were improved over those of the experimental example D. This is probably because although the drain pipe P is not provided, the recesses 34 and the like of the anode surface portions 30a, 50a, and 60a are used as the groove portions, so that the chlorine gas escapes faster than the experimental example D. .

  From each of the above experimental examples and comparative examples, the anode face portions 30a, 50a, 50a, 50a, It can be said that the zigzag-shaped portion ZG is imparted to 60a and the cathode surface portions 40b, 50b, 60b, the recesses 34, 44, etc. are set as grooves, and the significance of imparting the discharge pipe P is confirmed.

  In the present invention, the type, arrangement, number, and the like of the members are not limited to the above-described embodiments, and the components depart from the gist of the invention, such as appropriately replacing the constituent elements with those having the same operational effects. Of course, it can be appropriately changed within the range not to be.

  As described above, in the present invention, it is possible to suppress the heat generation due to the molten salt liquid resistance by narrowing the electrode interval, and suppress the deterioration of the electrolysis current efficiency and the increase of the electrolysis voltage, thereby reducing the power consumption during electrolysis. In the field of molten metal chloride electrolysis, in particular, a method for producing polysilicon for solar cells. It is expected to be widely applicable in the field of electrolysis of zinc chloride fused zinc chloride applicable to one zinc reduction method.

S ... Molten salt electrolysis apparatus P ... Discharge pipe U ... Electrode unit ZG ... Zigzag shaped part 10 ... Electrolytic tank 20 ... Molten salt 20a ... Liquid surface 30, 130, 230, 330, 430 ... Anode 30a ... Anode surface part 30c ... Upper surface 30d ... lower surface 32 ... convex portion 32a ... first inclined surface 32b ... second inclined surface 34, 134 ... concave portions 34a, 34b, 34c, 134a, 134b, 134c ... branch grooves 34a ', 34b', 34c '... projection 40 140 ... Cathode 40b ... Cathode surface portion 40c ... Upper surface 40d ... Lower surface 42 ... Convex portion 42a ... First inclined surface 42b ... Second inclined surface 42t ... End portion 44 ... Recess 46 ... Notch portion 146 ... Closure portion 148 ... Through hole 50 ... first intermediate electrode 50a ... anode surface portion 50b ... cathode surface portion 50c ... upper surface 50d ... lower surface 52 ... convex portion 54 ... recessed portion 56 ... notched portion 60 ... second intermediate electrode 60a ... anode surface portion 60b ... Pole face 60c ... upper surface 60d ... lower surface 70 ... insulating sheath 70a ... upper opening 70b ... lower opening 80a, 80b ... electrode rod

Claims (13)

An electrolytic cell containing a molten salt which is a molten metal chloride as an electrolytic solution;
An electrode unit to be immersed in the molten salt, having an anode having an anode surface portion and a cathode having a cathode surface portion facing the anode surface portion;
With
Each of the anode surface portion and the cathode surface portion is inclinedly arranged in an inclination direction inclined with respect to a first direction that is a vertical direction,
Each of the anode surface portion and the cathode surface portion corresponding to each other has a zigzag shape portion,
The zigzag-shaped portion has a first inclined surface and a second inclined surface that are continuous with each other , and protrudes in a second direction perpendicular to the inclined direction and extends in the inclined direction, and In the second direction, the first inclined surface and the second inclined surface extend in the inclined direction and are perpendicular to the inclined direction and the second direction while being recessed at a valley portion between adjacent ones. the third has a recess which is a groove exhibiting a constant width in the direction of, the convex portion及beauty the recess, in their state with each other corresponding ones had been adjacent to the inside of the front Symbol third direction is disposed,
The distance between the anode surface and the cathode surface portions, the molten salt electrolysis apparatus Ru der 5mm or more or less 1 mm.   The inclination angles of the zigzag-shaped portions of the anode surface portion and the cathode surface portion in the inclination direction are each set within a range of 10 degrees to 50 degrees, and the convex portion has a pair of inclined surfaces that are continuous at a ridge portion. 2. The molten salt electrolysis apparatus according to claim 1, wherein the zigzag-shaped portion has a zigzag angle in which an angle with respect to the third direction in each of the pair of slopes is set in a range of 5 degrees to 45 degrees. . Each of the grooves of the recess state, and are the width of 0.5mm or more in the third direction, the sum of the width of the groove, the plurality of recesses are provided in the anode surface and the cathode surface portions The molten salt electrolysis apparatus according to claim 2, wherein the molten salt electrolysis apparatus is 20% or less of a width in the third direction of the at least one of the at least one.   The molten salt electrolysis apparatus according to claim 3, wherein the width of the groove is widened in a depth direction of the groove.   The molten salt electrolysis apparatus according to claim 3 or 4, wherein the groove has a branch groove or a protrusion at a bottom portion in a depth direction of the groove.   The molten salt electrolysis apparatus according to any one of claims 3 to 5, further comprising a discharge pipe that surrounds the periphery of the upper end portion of the groove and opens above the liquid surface of the molten salt.   The molten salt electrolysis apparatus according to claim 6, wherein a material of the discharge pipe is any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz.   The molten salt electrolysis apparatus according to any one of claims 1 to 7, wherein the anode surface portion and the cathode surface portion are parallel to each other, and an electrolytic reaction space is defined therebetween. The molten salt electrolysis apparatus according to claim 8 , wherein the electrode unit further includes an insulating sheath that entirely covers the outer periphery of the anode and the cathode except for the top and bottom of the electrolytic reaction space. The molten salt electrolysis apparatus according to claim 9 , wherein a material of the insulating exterior is any one of alumina, mullite, silicon nitride, silicon carbide, graphite, and quartz. The molten salt electrolysis device according to any one of claims 1 to 10 , wherein the molten salt includes any one of sodium chloride, potassium chloride, lithium chloride, calcium chloride, aluminum chloride, magnesium chloride, and zinc chloride. The molten salt electrolysis apparatus according to claim 11 , wherein the molten salt is a single salt system containing zinc chloride. An electrode to be immersed in the molten salt, having an electrolytic cell for storing a molten salt, which is a molten metal chloride, as an electrolyte, an anode having an anode surface portion, and a cathode having a cathode surface portion facing the anode surface portion Each of the anode surface portion and the cathode surface portion is inclined in an inclined direction inclined with respect to a first direction that is a vertical direction, and the corresponding ones of the anode surface portion and the cathode surface portion are Each having a zigzag-shaped portion, and the zigzag-shaped portion has a first inclined surface and a second inclined surface that are connected to each other , and protrudes in a second direction perpendicular to the inclined direction. A convex portion extending in the direction, and extending in the inclined direction while being recessed at a valley portion between adjacent ones of the first inclined surface and the second inclined surface in the second direction and the inclined portion Direction and said second Has a recess which is a groove exhibiting a constant width in a third direction perpendicular to the direction, the convex portion及beauty the recess, in their state with each other corresponding ones had been adjacent to the inside of the front Stories is disposed in the third direction, the distance between the anode surface and the cathode surface portions, preparing a molten salt electrolysis apparatus Ru der 5mm or more or less 1 mm,
An electrolysis step in which an electrolysis gas is generated at the anode surface portion of the electrode, and an electrolysis metal having a specific gravity greater than that of the pre-molten salt is generated at the cathode surface portion corresponding to the anode surface portion;
Moving the corresponding electrolytically generated gas and electrolytically generated metal along the concave portion while collecting the corresponding one of the electrolytically generated metal and the electrolytically generated metal;
A molten salt electrolysis method comprising:

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