CA1108092A - Aluminum electrolytic cell - Google Patents
Aluminum electrolytic cellInfo
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- CA1108092A CA1108092A CA290,930A CA290930A CA1108092A CA 1108092 A CA1108092 A CA 1108092A CA 290930 A CA290930 A CA 290930A CA 1108092 A CA1108092 A CA 1108092A
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Abstract
Title of the Invention:
Aluminum Electrolytic Cell Abstract of the Disclosure:
An aluminum electrolytic cell wherein, in a sealed type electrolytic cell having a raw material aluminum chloride feeding port and chlorine gas discharging ports in the top part and a molten metal reservoir in the bottom part and provided with an electrode part in the intermediate part so that a molten salt electrolytic bath containing aluminum chloride is electrolyzed in the cell and molten aluminum is collected from the metal reservoir in the bottom part, the electrode part is formed of funnel-shaped electrodes laminated at a fixed distance between the electrodes or a pair of right and left electrode plate groups opposed to each other at a fixed distance between them and inclined to be lower inward at least one intermediate bi-polar electrode is provided between both cathode and anode and a gas rising passage is formed between the outer edges of the funnel-shaped electrodes or the electrode plates and -the inner wall of the cell to prevent the rechlorination of aluminum after the electrolysis.
Aluminum Electrolytic Cell Abstract of the Disclosure:
An aluminum electrolytic cell wherein, in a sealed type electrolytic cell having a raw material aluminum chloride feeding port and chlorine gas discharging ports in the top part and a molten metal reservoir in the bottom part and provided with an electrode part in the intermediate part so that a molten salt electrolytic bath containing aluminum chloride is electrolyzed in the cell and molten aluminum is collected from the metal reservoir in the bottom part, the electrode part is formed of funnel-shaped electrodes laminated at a fixed distance between the electrodes or a pair of right and left electrode plate groups opposed to each other at a fixed distance between them and inclined to be lower inward at least one intermediate bi-polar electrode is provided between both cathode and anode and a gas rising passage is formed between the outer edges of the funnel-shaped electrodes or the electrode plates and -the inner wall of the cell to prevent the rechlorination of aluminum after the electrolysis.
Description
g~
Background of the Invention;
Field of the Invention:
The present invention relates to electrolytic cells for obtaining aluminum from aluminum chloride by electro-lyzing a molten salt electrolytic ba~h containing molten aluminum chloride.
Description of the Prio~ Art:
An aluminum chloride electrolyzi.ng method of obtain-.ing al~lminum by holding and electrolyzing such halide molten salt electrolytic bath containing mol.ten alum inum chloride as, for example, an electrolytic bath of AlC13 - NaCl - LiCl system or AlC13 - MgC12 - NaCl system at a temperature akove the melting point of aluminum has such various advantages that it can be operated at an electrolyzing temperature near the temperature of 700C which is about 300C lower than in the Hall Heroult process and that, as the anode reaction product by the electrolysis is a chlorine gas, no reaction with graphite used an an electrode material will take place and therefore the electrode will not be worn, is therefore noted as an aluminum electrolyzing method of a type of saving energy and resources but is not yet fixed as of an industrial electrolytic cell.
However, considered most possible up to date is an electrolytic cell hy horizontal bi-polar electrodes manufactured recently by ALCOA*, U.S.A. (U.S. Patent No.
3,822,195).
The feature of this electrolytic cell of ALCOA is that many horizontal rectangular graphite electrode plates are *Trade Mark - .~
z set between both electrodes o~ an electrolYtiC cell filled with a halide molten salt containing aluminum chloride so as to produce a proper cl.earance from the inner wall of the cell and the aluminum chloride in the bath between ~he respective laminated electrodes is electrol.y~ed by passinc3 an electric current between both electrodes so as to pro-duce a chlorine gas between the anodes of the respective electrodes and molten aluminum grains on the cathode sur~
faces, the chlorine gas produced at the anodes is made to rise through the air gap formed between the electrodes and the inner wall of the cell as a rising passage from one side o~ the rectangular electrodes, a unidirectional cir-culating current of the electrolytic bath is formed by its rising force and, on the other hand, the molten alum~
inum grains produced at the cathodes move on the cathode surfaces due to the above mentioned circulating current, reach the gas rising passage, are lowered countercurrently against the circulating current through the gas rising passage by their own weight and are accumulated in the bottom of the cell.
However, in such AI.COA* electrolytic cell, as mentioned above, there have been defects that, as the chlorine gas and molten aluminum move countercurrently through the same gas rising passage and the chlorine gas produced at the anodes concentrates on one slde of the rectangle, the gas content in the electrolytic bath between the electrodes on the discharging side will be so large and the chances of the aluminum and chlorine gas contacting each other will be 50 many that the alum-inum ~ill be re-chlorinated and the current efficiency *Trade Mark ~ 3 --~ .
will be reduced.
Sun~ary o the Invention:
An object of the present invention is to provide an electrolytic cell wherein the deects of the above mentioned conventional electrolytic cell are ellminated and an efficient electrolysis of aluminum chloride can be made.
According to the invention there is provided a sealed electrolytic cell for electrolyzing a molten salt electro-lytic ba~h containing aluminum chloride to produce moltenaluminum metal which comprises a cell housing an electrical element in said housing comprising an array of at least three electrode plates inclined downwardly and inwardly towards the housing center in fixed generally parallel spaced apart relation, substantially centrally located apertures in all such plates in general~y vertical align-ment to define a common passageway extending vertically through said electrode array and outer passages defined between the outer side edges of said electrode plates and the inner wall o said cell housing, one outer electrode plate acting as a cathode, the other outer plate actiny as an anode and each intermediate plate acting as a bi-polar electrode, raw material inlet means at the top of said housing for introducing aluminum chloride into the elec-trolyte bath above and in substantial alignment with the central common passageway in said electrode plate array, chlorine gas discharying means at the top of said housing, and an aluminum metal collecting reservoir at the bottom of said housing below said electrode element.
Brief Description of the Drawings:
Fig. lA is a vertically sectional view of an embodiment ~ 8~ Z
of an electrolytic cell according to the present invention.
Fig. lB is a sectional view on line ~-B in Fig. lA.
Fig. 2 is a developed view of flan~e parts and sleeves in the respective electrodes in the embodiment in Fig. 1.
Fig. 3 is a vertically sectional view of another embodiment of the electrolytic cell according to the present invention.
Fig. 4 is a plan view of the embodiment in Fig. 3.
- 4a --~F
. .
, , . , ~ ,, .
Detailed Description of Preferred Embodiments:
In the embodiment in Figs. 1 and 2, numeral 1 indicates a cylindrical sealed type electrolytic cell formed of an outer plate 2 made o~ iron, an insulating glasswool layer 3, a refractory aluminum material 4 and a refractory nitride material 5 from outside. Numeral 6 indicates a sealing lid part provided in the top part of the electro-lytic cell 1 and formed the same as the electrolytic cell 1. A raw material feeding port 7 for introducing a raw material aluminum chloride vapor into a bath is provided in the center part of the lid part 6. A plurality of gas discharging ports 8 for discharging a chlorine gas gener-ated by an electrolysis out of the cell are provided in the peripheral side part of the lid part 6.
A reservoir 9 for molten aluminum obtained by the electrolysis is formed in the bottom part of the electro-lytic cell 1 and bricks made of graphite are used for the inner wall 10 of this part. Numeral 11 indicates an outlet port for collecting molten aluminum accumulated in the molten aluminum reservoir 9. A temperature regulating mechanism 12 is provided on the periphery of the outlet port 11 so that, by properly controlling the temperature of the inner wall of the outlet port 11, the thickness of the solidified metal layer 13 deposited on the inner wall can be adjusted and the metal delivering velocity can be thereby adjusted. 14, 15, 15 and 16 are funnel-shaped electrodes made of graphite, having respectively center holes 17 and peripheral clearances and concavely inclining toward the center holes 17. The respective electrodes 14, 15, 15 and 16 are arranged laminately at a proper distance between them on the vertical center axis of the , , 9~
electrolytic celi l and the uppermost electrode 14 and lowermost electrode 16 are fitted respectively with current passing terminals 18 and 19 so as to respectively form an anode and cathode~ A sleeve 17a made of such a refractory material as of alumina or nitride having a resistance to bath is fitted in each center hole 17 as a sealing material. By the way, the electrodes 15 located intermediately between both electrodes 14 and 16 act as a bi-polar electrode having functions as of both electrodes on both upper and lower surfaces. 20, 20', 20" , 20" ' and 20'''' are sleeves made of such the refractory material as of alumina or nitride having a resistance to bath for coating and protecting the outside surfaces of the elec-trodes 14, 15, 15 and 16 and holding the respective electrodes 14, 15, 15 and 16 at a fixed distance between them. The respective electrodes 14 J 15, 15 and 16 are supported by the above mentioned sleeves 20, 20', 20'', 20'" and 20"'' on flange parts 21, 21', 21" and 21" ' provided respectively on the peripheries of the lower ends.
Further, the above mentioned respective sleeves and flanges are provided respectively with incisions 23J 23', 23'' and 23' " and 24, 24', 247' and 24"' communicating at proper intervals. By the way, as seen in the developed view shown in Fig. 2, the incisions 24, 24', 24" and 24' " formed respectively in the above mentioned flange parts 21, 21' 22'' and 21'" had better have the openings made gradually larger with the approach to the upper part of the cell in which the amount of the gas is larger. 25 is a hood made of such refractory material as of alumina or nitride having a resistance to bath, connecting the center hole 17 of the upper most funnel-shaped electrode 14 with the above _ ~ _ 8~)~2 mentioned raw material feeding port 7 and having on the lower peripheral surface a plurality of passages 26 through which the electrolytic bath flows in. By the way, the hood 25 may be made by cylindrically stacking firebricks or the like.
The operation of the electrolytic cell formed as in this embodiment shall be described in the following.
When the cell 1 is first filled to the bath level 27 with a halide electrolytic bath containing aluminum chloride and an electric current is passed between both electrodes 14 and 16, the respective funnel-shaped electrodes 15 present as held between the electrodes 14 and 16 will become bi-polar electrodes and their upper surfaces and lower surfaces will function respectively as cathodes and anodes.
Therefore, by the electrolysis of aluminum chloride in the electrolytic bath present in the spaces between the respective electrodes 14, 15, 15 and 16, a chlorine gas will be produced on the anode surfaces and molten aluminum will be deposited in the form of grains on the cathode surfaces.
Now, as the respective electrodes 14, 15, 15 and 16 are funnel-shaped, the molten aluminum grains produced on the cathode surfaces will lower centripetally toward the center holes 17 along the sloped upper surfaces of the funnels and will fall into the center holes 17 to be accumulated in the molten metal reservoir 9. On the other hand, on the anodes, the produced chlorine gas will diffusely rise in the periph-eral direction along the sloped lower surfaces oE the funnels, will rise through the peripheral clearances (gas rising passages) through the incision 23, 23', 23l' and 23''' of the sleeves and the incisions 24, 24', 24'' and 24''' of the flanges and will be discharged out of the cell through the gas discharging ports ~ provided in the peripheral part ~1~8~9Z
of the lid part 6 in the cell top part.
In such case, the electrolytic bath contained in the above mentioned gas rising passages will produce a rising current due to the buoyant effect by the rising force of the chlorine 9as. On the contrary, a ~alling current will be produced in the center hole 17 of the electrode. Thus, as shown by the arrows in Fig. 1, the electrolytic bath will form a circulating current which will pass through between the respective electrodes 14, 15, 15 and 16 from the center hole 17, will reach the peripheral part of the cell, will rise through the peripheral clearances (gas rising passages), will be separated from the chlorine gas in the uppermost part and then will return to the center hole 17 again from the passages 26 of the hood 25O
By the way, in the case of laminating a plurality of funnel-shaped electrodes 14, 15, 15 and 16 at a fixed dis-tance between them, the electrodes having flanges which are also supporters are used in the dra~ing but, for example, the electrodes may be held by setting separators of stays by a plurality of fine alumina pipes. It is needless to say that, in such case, a proper gas rlsing passage will have to be provided between the electrodes and the inner wall of the cell. Also, the electrodes may be held only by cylindrical sleeves which may be made to communicate with the peripheral clearances ~gas rising passages) by providing incisions.
By the way, in this embodiment, the raw material feed-ing port 7 and the center hole 17 of the electrode are connected with each other through the hood 25 but the raw material aluminum chloride vapor can be bl.own directly into ~38~;~
the center hole of the electrode from the raw material ~eed-ing port without using the hood.
The embodiment in Figs. 3 and 4 shall be described in the following. In this embodiment, the same reference numerals are attached to the same respective parts as in Figs. 1 and
Background of the Invention;
Field of the Invention:
The present invention relates to electrolytic cells for obtaining aluminum from aluminum chloride by electro-lyzing a molten salt electrolytic ba~h containing molten aluminum chloride.
Description of the Prio~ Art:
An aluminum chloride electrolyzi.ng method of obtain-.ing al~lminum by holding and electrolyzing such halide molten salt electrolytic bath containing mol.ten alum inum chloride as, for example, an electrolytic bath of AlC13 - NaCl - LiCl system or AlC13 - MgC12 - NaCl system at a temperature akove the melting point of aluminum has such various advantages that it can be operated at an electrolyzing temperature near the temperature of 700C which is about 300C lower than in the Hall Heroult process and that, as the anode reaction product by the electrolysis is a chlorine gas, no reaction with graphite used an an electrode material will take place and therefore the electrode will not be worn, is therefore noted as an aluminum electrolyzing method of a type of saving energy and resources but is not yet fixed as of an industrial electrolytic cell.
However, considered most possible up to date is an electrolytic cell hy horizontal bi-polar electrodes manufactured recently by ALCOA*, U.S.A. (U.S. Patent No.
3,822,195).
The feature of this electrolytic cell of ALCOA is that many horizontal rectangular graphite electrode plates are *Trade Mark - .~
z set between both electrodes o~ an electrolYtiC cell filled with a halide molten salt containing aluminum chloride so as to produce a proper cl.earance from the inner wall of the cell and the aluminum chloride in the bath between ~he respective laminated electrodes is electrol.y~ed by passinc3 an electric current between both electrodes so as to pro-duce a chlorine gas between the anodes of the respective electrodes and molten aluminum grains on the cathode sur~
faces, the chlorine gas produced at the anodes is made to rise through the air gap formed between the electrodes and the inner wall of the cell as a rising passage from one side o~ the rectangular electrodes, a unidirectional cir-culating current of the electrolytic bath is formed by its rising force and, on the other hand, the molten alum~
inum grains produced at the cathodes move on the cathode surfaces due to the above mentioned circulating current, reach the gas rising passage, are lowered countercurrently against the circulating current through the gas rising passage by their own weight and are accumulated in the bottom of the cell.
However, in such AI.COA* electrolytic cell, as mentioned above, there have been defects that, as the chlorine gas and molten aluminum move countercurrently through the same gas rising passage and the chlorine gas produced at the anodes concentrates on one slde of the rectangle, the gas content in the electrolytic bath between the electrodes on the discharging side will be so large and the chances of the aluminum and chlorine gas contacting each other will be 50 many that the alum-inum ~ill be re-chlorinated and the current efficiency *Trade Mark ~ 3 --~ .
will be reduced.
Sun~ary o the Invention:
An object of the present invention is to provide an electrolytic cell wherein the deects of the above mentioned conventional electrolytic cell are ellminated and an efficient electrolysis of aluminum chloride can be made.
According to the invention there is provided a sealed electrolytic cell for electrolyzing a molten salt electro-lytic ba~h containing aluminum chloride to produce moltenaluminum metal which comprises a cell housing an electrical element in said housing comprising an array of at least three electrode plates inclined downwardly and inwardly towards the housing center in fixed generally parallel spaced apart relation, substantially centrally located apertures in all such plates in general~y vertical align-ment to define a common passageway extending vertically through said electrode array and outer passages defined between the outer side edges of said electrode plates and the inner wall o said cell housing, one outer electrode plate acting as a cathode, the other outer plate actiny as an anode and each intermediate plate acting as a bi-polar electrode, raw material inlet means at the top of said housing for introducing aluminum chloride into the elec-trolyte bath above and in substantial alignment with the central common passageway in said electrode plate array, chlorine gas discharying means at the top of said housing, and an aluminum metal collecting reservoir at the bottom of said housing below said electrode element.
Brief Description of the Drawings:
Fig. lA is a vertically sectional view of an embodiment ~ 8~ Z
of an electrolytic cell according to the present invention.
Fig. lB is a sectional view on line ~-B in Fig. lA.
Fig. 2 is a developed view of flan~e parts and sleeves in the respective electrodes in the embodiment in Fig. 1.
Fig. 3 is a vertically sectional view of another embodiment of the electrolytic cell according to the present invention.
Fig. 4 is a plan view of the embodiment in Fig. 3.
- 4a --~F
. .
, , . , ~ ,, .
Detailed Description of Preferred Embodiments:
In the embodiment in Figs. 1 and 2, numeral 1 indicates a cylindrical sealed type electrolytic cell formed of an outer plate 2 made o~ iron, an insulating glasswool layer 3, a refractory aluminum material 4 and a refractory nitride material 5 from outside. Numeral 6 indicates a sealing lid part provided in the top part of the electro-lytic cell 1 and formed the same as the electrolytic cell 1. A raw material feeding port 7 for introducing a raw material aluminum chloride vapor into a bath is provided in the center part of the lid part 6. A plurality of gas discharging ports 8 for discharging a chlorine gas gener-ated by an electrolysis out of the cell are provided in the peripheral side part of the lid part 6.
A reservoir 9 for molten aluminum obtained by the electrolysis is formed in the bottom part of the electro-lytic cell 1 and bricks made of graphite are used for the inner wall 10 of this part. Numeral 11 indicates an outlet port for collecting molten aluminum accumulated in the molten aluminum reservoir 9. A temperature regulating mechanism 12 is provided on the periphery of the outlet port 11 so that, by properly controlling the temperature of the inner wall of the outlet port 11, the thickness of the solidified metal layer 13 deposited on the inner wall can be adjusted and the metal delivering velocity can be thereby adjusted. 14, 15, 15 and 16 are funnel-shaped electrodes made of graphite, having respectively center holes 17 and peripheral clearances and concavely inclining toward the center holes 17. The respective electrodes 14, 15, 15 and 16 are arranged laminately at a proper distance between them on the vertical center axis of the , , 9~
electrolytic celi l and the uppermost electrode 14 and lowermost electrode 16 are fitted respectively with current passing terminals 18 and 19 so as to respectively form an anode and cathode~ A sleeve 17a made of such a refractory material as of alumina or nitride having a resistance to bath is fitted in each center hole 17 as a sealing material. By the way, the electrodes 15 located intermediately between both electrodes 14 and 16 act as a bi-polar electrode having functions as of both electrodes on both upper and lower surfaces. 20, 20', 20" , 20" ' and 20'''' are sleeves made of such the refractory material as of alumina or nitride having a resistance to bath for coating and protecting the outside surfaces of the elec-trodes 14, 15, 15 and 16 and holding the respective electrodes 14, 15, 15 and 16 at a fixed distance between them. The respective electrodes 14 J 15, 15 and 16 are supported by the above mentioned sleeves 20, 20', 20'', 20'" and 20"'' on flange parts 21, 21', 21" and 21" ' provided respectively on the peripheries of the lower ends.
Further, the above mentioned respective sleeves and flanges are provided respectively with incisions 23J 23', 23'' and 23' " and 24, 24', 247' and 24"' communicating at proper intervals. By the way, as seen in the developed view shown in Fig. 2, the incisions 24, 24', 24" and 24' " formed respectively in the above mentioned flange parts 21, 21' 22'' and 21'" had better have the openings made gradually larger with the approach to the upper part of the cell in which the amount of the gas is larger. 25 is a hood made of such refractory material as of alumina or nitride having a resistance to bath, connecting the center hole 17 of the upper most funnel-shaped electrode 14 with the above _ ~ _ 8~)~2 mentioned raw material feeding port 7 and having on the lower peripheral surface a plurality of passages 26 through which the electrolytic bath flows in. By the way, the hood 25 may be made by cylindrically stacking firebricks or the like.
The operation of the electrolytic cell formed as in this embodiment shall be described in the following.
When the cell 1 is first filled to the bath level 27 with a halide electrolytic bath containing aluminum chloride and an electric current is passed between both electrodes 14 and 16, the respective funnel-shaped electrodes 15 present as held between the electrodes 14 and 16 will become bi-polar electrodes and their upper surfaces and lower surfaces will function respectively as cathodes and anodes.
Therefore, by the electrolysis of aluminum chloride in the electrolytic bath present in the spaces between the respective electrodes 14, 15, 15 and 16, a chlorine gas will be produced on the anode surfaces and molten aluminum will be deposited in the form of grains on the cathode surfaces.
Now, as the respective electrodes 14, 15, 15 and 16 are funnel-shaped, the molten aluminum grains produced on the cathode surfaces will lower centripetally toward the center holes 17 along the sloped upper surfaces of the funnels and will fall into the center holes 17 to be accumulated in the molten metal reservoir 9. On the other hand, on the anodes, the produced chlorine gas will diffusely rise in the periph-eral direction along the sloped lower surfaces oE the funnels, will rise through the peripheral clearances (gas rising passages) through the incision 23, 23', 23l' and 23''' of the sleeves and the incisions 24, 24', 24'' and 24''' of the flanges and will be discharged out of the cell through the gas discharging ports ~ provided in the peripheral part ~1~8~9Z
of the lid part 6 in the cell top part.
In such case, the electrolytic bath contained in the above mentioned gas rising passages will produce a rising current due to the buoyant effect by the rising force of the chlorine 9as. On the contrary, a ~alling current will be produced in the center hole 17 of the electrode. Thus, as shown by the arrows in Fig. 1, the electrolytic bath will form a circulating current which will pass through between the respective electrodes 14, 15, 15 and 16 from the center hole 17, will reach the peripheral part of the cell, will rise through the peripheral clearances (gas rising passages), will be separated from the chlorine gas in the uppermost part and then will return to the center hole 17 again from the passages 26 of the hood 25O
By the way, in the case of laminating a plurality of funnel-shaped electrodes 14, 15, 15 and 16 at a fixed dis-tance between them, the electrodes having flanges which are also supporters are used in the dra~ing but, for example, the electrodes may be held by setting separators of stays by a plurality of fine alumina pipes. It is needless to say that, in such case, a proper gas rlsing passage will have to be provided between the electrodes and the inner wall of the cell. Also, the electrodes may be held only by cylindrical sleeves which may be made to communicate with the peripheral clearances ~gas rising passages) by providing incisions.
By the way, in this embodiment, the raw material feed-ing port 7 and the center hole 17 of the electrode are connected with each other through the hood 25 but the raw material aluminum chloride vapor can be bl.own directly into ~38~;~
the center hole of the electrode from the raw material ~eed-ing port without using the hood.
The embodiment in Figs. 3 and 4 shall be described in the following. In this embodiment, the same reference numerals are attached to the same respective parts as in Figs. 1 and
2.
The greatest difference between this embodiment and the above described embodiment is that pairs of right and left inclidined electrode plate groups are provided instead of the funnel-shaped electrodes made of graphite and used in the above described embodiment. That is to say, 14a, 15a, --- l5a, 16a and 14'a, 15'a, --- 15'a, 16'a are pairs of righ~ and left inclined electrode plate groups provided as respectively opposed to each other on the right and left.
14a and 14'a are anodes. 16a and 16'a are cathodes. 15a, 15a --- 15'a, 15'a --- ~respectively four pairs in the draw-ing) are bi-polar electrodes formed respectively between the anodes and cathodes 14a, 16a and 14'a, 16'a. The respective upper surfaces function as cathodes and the respective lower surfaces function as anodes.
The respective electrode plates are kept at a fixed distance between them respectively by spacers 28, 28, ---28', 28' ---, the anodes 14a and 14'a and cathodes 16a and 16'a are held in an outer casing respectively by conductive rods 18, 18' and 19, 19' and the conductive rods 19 and 19' are positively supported by refractory materials 30. These right and left electrode plate groups are provided as opposed to each other with a fixed clearance between them. A falling passage 17a for the electrolytic bath and molten metal is formed between them. Further, rising passages 29 and 29' for .~
8`~
the electrolytic bath and chlorine gas are ~ormed between the respective electrode plate groups 14a, 15a, - - 15a. 16a and 14'a, 15'a, --- 15'a, 16'a and the inner wall (refractory material layer 5) of the elect~olytic cell. By the way, it is preferrable that the above mentioned rising passages 29 and 29' are made wider with the approach to the upper part of the cell in which the amount of the gas is larger.
Now, the operation of the electrolytic bath of this embodiment is substantlally the same as of the above des-cribed embodiment~ When the cell is first filled to thebath level 27 with a halide electrolytic bath containing aluminum chloride and an electric current is passed between both electrodes 14a, 16a and 14'a, 16'a of the right and left electrode plate groups, the respective electrode plates 15a and 15'a present as held between both electrodes 14a and 16a' and between both electrodes 14'a and 16a' will operate as bi-polar electrodes in which thir upper surfaces will function as cathodes and their lower surfaces will function as anodes. The aluminum chloride in the electrolytic bath present in the spaces between the respective electrode 14a, 15a, --- 15a, 16a and between the respective electrodes l~a', 15a', --- 15a', 16' will be electrolvzed~ a chlorine gas will be produced on the anode surfaces and molten aluminum will be deposited in the form of grains on the cathode surfaces.
However, as the respective electrode plates 14a, 15a, --lSa, 16a and 14a', 15a', --- 15a', l~a' slant to lower inward, the molten aluminum grains produced on the cathode surfaces will lower due to their own weight inward of the cell along the sloped upper surfaces of the electrode plates, will further fall into the passage 17a formed in the ~,.
clearance between both electrode plate groups and will be accumulated in the molten metal reservoir 9.
On the other hand, the chlorine gas produced on th~
anode surfaces will rise outward of the cell along the sloped lower surfaces of the respective electrode plates, will rise through the rising passages 29 and 29' formed of the clearances between the outer ends of the electrode plates and the inner wall of the cell and will be discharged out of the cell thro~lgh the gas discharging ports 8 provided in the lid part in the top part of the cell.
In such case, the electrolytic bath contained in the above mentioned rising passayes 29 and 29' will be subjected to the buoyancy effect by the rise of the chlorine gas and will prodce a rising current. On the other hand, a falling current will be produced on the contrary in the falling pas-sage 17a formed between the right and left electrode plate groups and, therefore, as indicated by the arrows in Fi~. 3, the electrolytic bath in the cell will form a circulating current which will go outward in the cell through between the respective electrode plates 14a, 15a, --- 15a~ 16, 14'a, 15'a, --- 15'a 16'a, will rise through the gas rising pas-sages 29 and 29', will reach the upper part of the cell and will return again to the falling passage 17a between the respective electrode plate groups.
As explained in the above, according to the present invention, as the electrode part arranged in the intermediate part of the electrolytic cell is formed to incline so as to be lower inward, the chlorine gas produced on the anode ~ur-faces of the electrodes will quickly rise along the sloped lower surfaces of the electrode plates and, on the other hand, the molten aluminum grains deposited on the cathode surfaces of the electrodes will quickly lower due to their own weight along the sloped upper surfaces of the electrode plates and therefore the chances of the a]uminum being re-chlorinated will be remarkably few. Further, as the chlorine gas rising passage and the molten metal falling passage are respectively independent of each other, the chances of the aluminum and chlorine gas contacting each other in these parts will be also few and therefore it will be possible to substantially perfectly prevent the loss by the re-oxidation.
By the way, from the viewpoint of the structure and the current efficiency in the case o~ the electrolysis, it is proper that the angle of inclination of the inclined electrode plates set in the embodiment of the present invention is about 10 to 50 degrees.
Further, the present invention is not limited to the above mentioned embodiment. For example, in the case of obtaining an electrolytic cell of a large capacity, the above mentioned pair of electrode plate groups may be made one set and a plurality of such sets may be arranged in parallel.
The greatest difference between this embodiment and the above described embodiment is that pairs of right and left inclidined electrode plate groups are provided instead of the funnel-shaped electrodes made of graphite and used in the above described embodiment. That is to say, 14a, 15a, --- l5a, 16a and 14'a, 15'a, --- 15'a, 16'a are pairs of righ~ and left inclined electrode plate groups provided as respectively opposed to each other on the right and left.
14a and 14'a are anodes. 16a and 16'a are cathodes. 15a, 15a --- 15'a, 15'a --- ~respectively four pairs in the draw-ing) are bi-polar electrodes formed respectively between the anodes and cathodes 14a, 16a and 14'a, 16'a. The respective upper surfaces function as cathodes and the respective lower surfaces function as anodes.
The respective electrode plates are kept at a fixed distance between them respectively by spacers 28, 28, ---28', 28' ---, the anodes 14a and 14'a and cathodes 16a and 16'a are held in an outer casing respectively by conductive rods 18, 18' and 19, 19' and the conductive rods 19 and 19' are positively supported by refractory materials 30. These right and left electrode plate groups are provided as opposed to each other with a fixed clearance between them. A falling passage 17a for the electrolytic bath and molten metal is formed between them. Further, rising passages 29 and 29' for .~
8`~
the electrolytic bath and chlorine gas are ~ormed between the respective electrode plate groups 14a, 15a, - - 15a. 16a and 14'a, 15'a, --- 15'a, 16'a and the inner wall (refractory material layer 5) of the elect~olytic cell. By the way, it is preferrable that the above mentioned rising passages 29 and 29' are made wider with the approach to the upper part of the cell in which the amount of the gas is larger.
Now, the operation of the electrolytic bath of this embodiment is substantlally the same as of the above des-cribed embodiment~ When the cell is first filled to thebath level 27 with a halide electrolytic bath containing aluminum chloride and an electric current is passed between both electrodes 14a, 16a and 14'a, 16'a of the right and left electrode plate groups, the respective electrode plates 15a and 15'a present as held between both electrodes 14a and 16a' and between both electrodes 14'a and 16a' will operate as bi-polar electrodes in which thir upper surfaces will function as cathodes and their lower surfaces will function as anodes. The aluminum chloride in the electrolytic bath present in the spaces between the respective electrode 14a, 15a, --- 15a, 16a and between the respective electrodes l~a', 15a', --- 15a', 16' will be electrolvzed~ a chlorine gas will be produced on the anode surfaces and molten aluminum will be deposited in the form of grains on the cathode surfaces.
However, as the respective electrode plates 14a, 15a, --lSa, 16a and 14a', 15a', --- 15a', l~a' slant to lower inward, the molten aluminum grains produced on the cathode surfaces will lower due to their own weight inward of the cell along the sloped upper surfaces of the electrode plates, will further fall into the passage 17a formed in the ~,.
clearance between both electrode plate groups and will be accumulated in the molten metal reservoir 9.
On the other hand, the chlorine gas produced on th~
anode surfaces will rise outward of the cell along the sloped lower surfaces of the respective electrode plates, will rise through the rising passages 29 and 29' formed of the clearances between the outer ends of the electrode plates and the inner wall of the cell and will be discharged out of the cell thro~lgh the gas discharging ports 8 provided in the lid part in the top part of the cell.
In such case, the electrolytic bath contained in the above mentioned rising passayes 29 and 29' will be subjected to the buoyancy effect by the rise of the chlorine gas and will prodce a rising current. On the other hand, a falling current will be produced on the contrary in the falling pas-sage 17a formed between the right and left electrode plate groups and, therefore, as indicated by the arrows in Fi~. 3, the electrolytic bath in the cell will form a circulating current which will go outward in the cell through between the respective electrode plates 14a, 15a, --- 15a~ 16, 14'a, 15'a, --- 15'a 16'a, will rise through the gas rising pas-sages 29 and 29', will reach the upper part of the cell and will return again to the falling passage 17a between the respective electrode plate groups.
As explained in the above, according to the present invention, as the electrode part arranged in the intermediate part of the electrolytic cell is formed to incline so as to be lower inward, the chlorine gas produced on the anode ~ur-faces of the electrodes will quickly rise along the sloped lower surfaces of the electrode plates and, on the other hand, the molten aluminum grains deposited on the cathode surfaces of the electrodes will quickly lower due to their own weight along the sloped upper surfaces of the electrode plates and therefore the chances of the a]uminum being re-chlorinated will be remarkably few. Further, as the chlorine gas rising passage and the molten metal falling passage are respectively independent of each other, the chances of the aluminum and chlorine gas contacting each other in these parts will be also few and therefore it will be possible to substantially perfectly prevent the loss by the re-oxidation.
By the way, from the viewpoint of the structure and the current efficiency in the case o~ the electrolysis, it is proper that the angle of inclination of the inclined electrode plates set in the embodiment of the present invention is about 10 to 50 degrees.
Further, the present invention is not limited to the above mentioned embodiment. For example, in the case of obtaining an electrolytic cell of a large capacity, the above mentioned pair of electrode plate groups may be made one set and a plurality of such sets may be arranged in parallel.
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A sealed electrolytic cell for electrolyzing a molten salt electrolytic bath containing aluminum chloride to produce molten aluminum metal which comprises a cell housing an electrical element in said housing comprising an array of at least three electrode plates inclined down-wardly and inwardly towards the housing center in fixed generally parallel spaced apart relation, substantially centrally located apertures in all such plates in gen-erally vertical alignment to define a common passageway extending vertically through said electrode array and outer passages defined between the outer side edges of said electrode plates and the inner wall of said cell housing, one outer electrode plate acting as a cathode, the other outer plate acting as an anode and each inter-mediate plate acting as a bi-polar electrode, raw material inlet means at the top of said housing for introducing aluminum chloride into the electrolyte bath above and in substantial alignment with the central common passageway in said electrode plate array, chlorine gas discharging means at the top of said housing, and an aluminum metal collecting reservoir at the bottom of said housing below said electrode element.
2. The aluminum electrolytic cell according to claim 1 wherein said electrode plates are funnel-shaped and a hole is made in the center thereof to form said central aperture.
3. The aluminum electrolytic cell according to claim 1 wherein each said electrode plate is formed by a pair of rightwardly and leftwardly inclined electrode plates, the inside edges of each such pair being spaced apart a fixed distance to form said central aperture.
4. The aluminum electrolytic cell according to claim 1 wherein a hood is disposed between said raw material feeding means and the uppermost electrode plate, said hood extending at its lower margins into said electrolyte bath and having passages for the electrolytic bath in said margins.
5. The aluminum electrolytic cell according to claim 1 wherein said outer passages are made generally wider in the direction of the top of the cell housing.
6. The aluminum electrolytic cell according to claim 3 wherein the angle of inclination of said inclined elec-trode plates is 10 to 50 degrees from the horizontal.
7. The aluminum electrolytic cell according to claim 2 wherein said funnel-shaped electrode plates are maintained with a fixed spacing between them by a plurality of flanges provided at the outer peripheries thereof and cooperating sleeves fitted to the inner wall of the cell housing for supporting the flanges.
8. The aluminum electrolytic cell according to claim 3 wherein said electrode plates are held with a fixed spacing by spacers.
9. A sealed electrolytic cell including a housing having a top cover provided generally at the center thereof with a raw material feeding port and adjacent its periphery with at least one gas discharging port, and a bottom wall defining a molten metal reservoir and a metal outlet port, and with said housing a plurality of funnel-shaped electrode plates having generally centrally located holes therein in alignment with said feeding port, said electrode plates being stacked with fixed clearance so as to form at least one intermediate bi-polar electrode between a cathode and an anode plate, and means defining an adequate gas rising passage formed between the outer peripheral side edge of each of the electrode plates and the inner wall of the housing, said raw material feeding port being connected to the center hole of the uppermost funnel-shaped electrode through a hood.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA290,930A CA1108092A (en) | 1977-11-15 | 1977-11-15 | Aluminum electrolytic cell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA290,930A CA1108092A (en) | 1977-11-15 | 1977-11-15 | Aluminum electrolytic cell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108092A true CA1108092A (en) | 1981-09-01 |
Family
ID=4110036
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA290,930A Expired CA1108092A (en) | 1977-11-15 | 1977-11-15 | Aluminum electrolytic cell |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1108092A (en) |
-
1977
- 1977-11-15 CA CA290,930A patent/CA1108092A/en not_active Expired
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