Electrolytic cell intended for the production of aluminium and electrolytic smelter comprising this cell

Abstract

This cell (1) comprises a pot shell (2) having two longitudinal sides (18) which are symmetrical in relation to a longitudinal median plane (P) of the electrolytic cell (1), an anode assembly which can only move in vertical translation with respect to the pot shell (2), the anode assembly comprising an anode block (100) and a transverse anode support (200) extending at right angles to the longitudinal sides (18) of the pot shell (2), from which support the anode block (100) is suspended. The anode support (200) comprises two connecting portions (202) from which electrolysis current is supplied to the anode support (200), and the cell (1) comprises electrical connection conductors (20) electrically connected to the two connecting portions (202) of the anode support (200), the two connecting portions (202) being located on either side of the plane (P).

Claims

1. An electrolytic cell configured for the production of aluminum by electrolysis, in which the electrolytic cell comprises a pot shell having two opposite longitudinal sides, an anode assembly configured to only move in vertical translation with respect to the pot shell and designed to be removed and replaced periodically, the anode assembly comprising at least one anode block and a transverse anode support extending substantially transversely to the longitudinal sides of the pot shell from which the at least one anode block is suspended, the transverse anode support comprising two connecting portions through which the transverse anode support is provided with electrolysis current, the electrolytic cell further comprising electrical connection conductors that are not configured to be removed and replaced periodically with the anode assembly, the electrical connection conductors being electrically connected to the two connecting portions of the transverse anode support, characterized in that the two connecting portions are at a distance from each other in a substantially transverse direction of the electrolytic cell, wherein the anode assembly is removably connected to the electrolytic cell such that the two connecting portions of the transverse anode support are removably connected to the electrical connection conductors, and wherein the anode assembly is supported by the electrical connection conductors and moveable with the electrical connection conductors.

2. The electrolytic cell according to claim 1, characterized in that the two opposite longitudinal sides are substantially symmetrical in relation to a longitudinal median plane of the electrolytic cell and characterized in that the two connecting portions are located on either side of the longitudinal median plane.

3. The electrolytic cell according to claim 2, characterized in that the transverse anode support comprises two end portions, and characterized in that the connecting portions are located on the end portions of the transverse anode support.

4. The electrolytic cell according to claim 1, characterized in that the transverse anode support comprises a first structure made of a first electrically conducting material and a second structure made of a second electrically conducting material, the second material having an electrical conductivity which is substantially greater than an electrical conductivity of the first material.

5. The electrolytic cell according to claim 4, characterized in that the first structure comprises a transverse bar extending substantially transversely from one connecting portion to the other connecting portion.

6. The electrolytic cell according to claim 5, characterized in that the transverse bar extends between the end portions in a single piece.

7. The electrolytic cell according to claim 4, characterized in that the second structure is attached to the first structure in such a way that the first structure mechanically supports the second structure.

8. The electrolytic cell according to claim 4, characterized in that the second structure at least partly forms the connecting portions of the anode support.

9. The electrolytic cell according to claim 4, characterized in that the second structure comprises two separate parts each at least partly forming one of the two connecting portions.

10. The electrolytic cell according to claim 9, characterized in that the two separate parts are distant from each other in the substantially transverse direction of the cell.

11. The electrolytic cell according to claim 10, characterized in that the two opposite longitudinal sides are substantially symmetrical in relation to a longitudinal median plane of the electrolytic cell, and in that the two separate parts are located on either side of the longitudinal median plane.

12. The electrolytic cell according to claim 11, characterized in that the two separate parts are substantially symmetrical in relation to the longitudinal median plane.

13. The electrolytic cell according to claim 10, characterized in that the transverse anode support comprises a plurality of stubs attached to the first structure designed to be sealed in voids formed in a surface of said at least one anode block, and characterized in that a distance between the two separate parts in the substantially transverse direction is equivalent to a distance between two adjacent stubs of the plurality of stubs.

14. The electrolytic cell according to claim 10, characterized in that the transverse anode support comprises a plurality of stubs attached to the first structure and that each of the two separate parts is attached to the first structure only at a location where the stubs and one of the connecting portions are attached.

15. The electrolytic cell according to claim 9, characterized in that the anode assembly comprises two adjacent anode blocks in the substantially transverse direction of the electrolytic cell, the two anode blocks being supported by the same first structure and located beneath the two separate parts of the second structure.

16. The electrolytic cell according to claim 4, characterized in that the first structure forms a ring, and in that the second structure is located within the ring formed by the first structure.

17. The electrolytic cell according to claim 16, characterized in that the ring has U-shaped ends, the second structure comprising two parts, each having a corresponding U-shape matching the U-shape of the ends of the ring, and characterized in that at ambient temperature a length of an outer perimeter wall of curved portions of the corresponding U-shape formed by each part of the second structure is shorter than a length of an inner perimeter wall in curved portions of the U-shape formed by the end of the ring matching the corresponding U-shape.

18. The electrolytic cell according to claim 1, characterized in that the anode support forms a ring bounded by two transverse bars connected together at ends thereof, the transverse bars extending substantially parallel to each other and perpendicular to the longitudinal sides of the pot shell.

19. The electrolytic cell according to claim 16, characterized in that the anode assembly comprises two adjacent anode blocks in a longitudinal direction of the electrolytic cell, each anode block being supported by one separate transverse bar of the two transverse bars.

20. The electrolytic cell according to claim 1, characterized in that the anode assembly comprises a plurality of stubs extending between the anode support and the at least one anode block, and characterized in that the anode support comprises a portion which is elbowed in a vertical plane at each end of the portion in such a way that the connecting portions of the anode support are located above the top surface of the stubs.

21. The electrolytic cell according to claim 1, characterized in that the anode assembly comprises a plurality of stubs extending substantially vertically between the anode support and the at least one anode block, and in that the stub comprises a substantially horizontal sealing end sealed within the at least one anode block.

22. The electrolytic cell according to claim 1, characterized in that the longitudinal sides extend in a substantially longitudinal direction, and each of the at least one anode block has a length extending in the substantially transverse direction and a width extending in the substantially longitudinal direction, wherein the length of each of the at least one anode block is greater than the width, and wherein the transverse anode support extends along the length of each of the at least one anode block.

23. The electrolytic cell according to claim 1, characterized in that the electrical connection conductors comprise a first electrical connection conductor located along one of the longitudinal sides and a second electrical connection conductor located along an opposite one of the longitudinal sides.

24. The electrolytic cell according to claim 1, characterized in that the electrical connection conductors extend along each of the longitudinal sides of the pot shell.

25. The electrolytic cell according to claim 1, further comprising connectors removably connecting the two connecting portions of the transverse anode support to the electrical connection conductors.

26. The electrolytic cell according to claim 1, characterized in that the anode assembly is removably connected to the electrolytic cell such that the entire anode assembly, including the at least one anode block and the transverse anode support, is removable together as a single unit.

27. An electrolysis plant comprising a row of electrolytic cells according to claim 1, arranged electrically in series, characterized in that the electrolytic cells are located transversely in relation to a length of the row.

28. An electrolytic cell configured for the production of aluminum by electrolysis, in which the electrolytic cell comprises a pot shell having two opposite longitudinal sides, an anode assembly configured to only move in vertical translation with respect to the pot shell and designed to be removed and replaced periodically, the anode assembly comprising at least one anode block and a transverse anode support extending substantially transversely to the longitudinal sides of the pot shell from which the at least one anode block is suspended, the transverse anode support comprising two connecting portions through which the transverse anode support is provided with electrolysis current, the electrolytic cell further comprising electrical connection conductors that are not configured to be removed and replaced periodically with the anode assembly, the electrical connection conductors being electrically connected to the two connecting portions of the transverse anode support, characterized in that the two connecting portions are at a distance from each other in a substantially transverse direction of the electrolytic cell, wherein the anode assembly is removably connected to the electrolytic cell such that the two connecting portions of the transverse anode support are removably connected to the electrical connection conductors, and wherein the electrical connection conductors do not extend over any part of the anode assembly.

29. An electrolytic cell configured for the production of aluminum by electrolysis, in which the electrolytic cell comprises a pot shell having two opposite longitudinal sides, an anode assembly configured to only move in vertical translation with respect to the pot shell and designed to be removed and replaced periodically, the anode assembly comprising at least one anode block and a transverse anode support extending substantially transversely to the longitudinal sides of the pot shell from which the at least one anode block is suspended, the transverse anode support comprising two connecting portions through which the transverse anode support is provided with electrolysis current, the electrolytic cell further comprising electrical connection conductors that are not configured to be removed and replaced periodically with the anode assembly, the electrical connection conductors being electrically connected to the two connecting portions of the transverse anode support, characterized in that the two connecting portions are at a distance from each other in a substantially transverse direction of the electrolytic cell, wherein the anode assembly is removably connected to the electrolytic cell such that the two connecting portions of the transverse anode support are removably connected to the electrical connection conductors, and wherein the electrical connection conductors are arranged fully under the anode support of the anode assembly.

30. An electrolytic cell configured for the production of aluminum by electrolysis, in which the electrolytic cell comprises a pot shell having two opposite longitudinal sides, an anode assembly configured to only move in vertical translation with respect to the pot shell and designed to be removed and replaced periodically, the anode assembly comprising at least one anode block and a transverse anode support extending substantially transversely to the longitudinal sides of the pot shell from which the at least one anode block is suspended, the transverse anode support comprising two connecting portions through which the transverse anode support is provided with electrolysis current, the electrolytic cell further comprising electrical connection conductors that are not configured to be removed and replaced periodically with the anode assembly, the electrical connection conductors being electrically connected to the two connecting portions of the transverse anode support, characterized in that the two connecting portions are at a distance from each other in a substantially transverse direction of the electrolytic cell, wherein the anode assembly is removably connected to the electrolytic cell such that the two connecting portions of the transverse anode support are removably connected to the electrical connection conductors, and wherein the electrical connection conductors connect directly to a bottom surface of the transverse anode support.

Description

(1) Other features and advantages of this invention will be clearly apparent from the following detailed description of an embodiment provided by way of a non-limiting example with reference to the appended drawings, in which:

(2) FIG. 1 is a schematic view from the side in cross-section of an electrolytic cell according to one embodiment of the invention,

(3) FIG. 2 is a schematic view from the side in cross-section of an electrolytic cell according to one embodiment of the invention,

(4) FIG. 3 is a schematic view from the side of an anode assembly of an electrolytic cell according to one embodiment of the invention,

(5) FIG. 4 is a view of the anode assembly in FIG. 3 from above,

(6) FIG. 5 is a view in cross-section along the line I-I in FIG. 3 of the side respectively on which an anode assembly is illustrated,

(7) FIG. 6 is a schematic view from the side of an anode assembly of an electrolytic cell according to one embodiment of the invention,

(8) FIG. 7 is a view of the anode assembly in FIG. 6 from above,

(9) FIG. 8 is a view in cross-section along the line II-II in Figure FIG. 6,

(10) FIG. 9 is a side view in schematic cross-section of an anode assembly of an electrolytic cell according to one embodiment of the invention,

(11) FIG. 10 is a schematic view from above of an anode assembly of an electrolytic cell according to one embodiment of the invention,

(12) FIG. 11 is a schematic side view in cross-section along the line III-Ill in FIG. 10,

(13) FIG. 12 is a schematic view from above of an anode assembly of an electrolytic cell according to one embodiment of the invention,

(14) FIG. 13 is a schematic side view in cross-section along the line IV-IV in FIG. 12,

(15) FIG. 14 is a schematic perspective view of an anode assembly in FIGS. 12 and 13,

(16) FIG. 15 is a schematic view from above of an anode assembly of an electrolytic cell according to one embodiment of the invention,

(17) FIG. 1 shows electrolytic cells 1 according to one embodiment of the invention which are intended for the production of aluminum by electrolysis.

(18) Electrolytic cells 1 comprise a pot shell 2, made in particular of steel, within which there is a lining 4 of refractory materials, a cathode 6 of carbon material, through which pass cathode conductors 8 designed to collect the electrolysis current at cathode 6 to route it to cathode collector bars 10, passing through the base or sides of pot shell 2, linking conductors 12 running substantially horizontally as far as the next electrolytic cell 1 from cathode collector bars 10, an electrolyte bath 14, in which alumina is dissolved, and a layer 16 of liquid metal, in particular liquid aluminum, which forms during the electrolysis reaction.

(19) Pot shell 2 may be of substantially parallelepiped shape. It comprises two opposite longitudinal sides 18, which are substantially symmetrical in relation to a longitudinal median plane P of electrolytic cell 1. Pot shell 2 may have two transverse sides connecting the longitudinal sides substantially bounding a rectangle.

(20) By longitudinal median plane is meant the plane substantially perpendicular to a transverse direction X of electrolytic cell 1 separating electrolytic cell 1 into two substantially equal parts.

(21) It will be noted that electrolytic cell 1 is arranged transversely in relation to the length of a row of electrolytic cells. In other words electrolytic cell 1 extends lengthwise in a longitudinal direction Y which is substantially perpendicular to the X direction in which the row of electrolytic cells, which electrolytic cell 1 belongs to, extends.

(22) Electrolytic cell 1 according to the invention also comprises an anode assembly. The anode assembly comprises one or more anode blocks 100 and a transverse anode support 200 extending transversely in relation to the length of electrolytic cell 1, from which anode block or blocks 100 is/are suspended.

(23) Anode blocks 100 are more particularly made of carbon material of the pre-baked type, i.e. baked before being placed in electrolytic cell 1.

(24) The anode assembly can only move in translation, in particular in vertical translation, in relation to pot shell 2. Electrolytic cell 1 is also configured to allow an anode assembly to be changed via the top, as illustrated in FIG. 1 for cell 1 located to the right of FIG. 1.

(25) As shown in FIG. 1 or 2, transverse anode support 200 extends substantially at right angles to the longitudinal sides 18 of pot shell 2. In other words transverse anode support 200 extends in a substantially transverse direction X of electrolytic cell 1.

(26) Transverse anode support 200 comprises two connecting portions 202. Electrolysis current is provided to anode support 200 via these connecting portions 202.

(27) Electrolytic cell 1 further comprises electrical connection conductors 20, electrically connected to two connecting portions 202, to carry electrolysis current to anode support 200.

(28) Electrical connection conductors 20 extend substantially vertically along each longitudinal side 18 of pot shell 2.

(29) It will be noted that the two connecting portions 202 are located on either side of plane P so that anode support 200 benefits from connection on both sides.

(30) The two connecting portions 202 are separate and distant from each other in a substantially transverse direction X of electrolytic cell 1.

(31) The two connecting portions 202 may be arranged substantially symmetrically in relation to plane P.

(32) They may be arranged at each of the two ends of transverse anode support 200.

(33) In particular, connecting portions 202 may be arranged close to longitudinal sides 18 of pot shell 2.

(34) More specifically, they may be arranged substantially vertically above the longitudinal sides 18 of pot shell 2, or more advantageously they may not extend beyond pot shell 2, i.e. they may be arranged outside the volume obtained by the vertical translation of a surface projected onto a horizontal plane by pot shell 2.

(35) Connecting portions 202 are therefore less exposed to the heat released by electrolytic bath 14 when in operation.

(36) As shown in FIGS. 10 and 12, anode support 200 is in the form of a ring. In particular, it comprises two longitudinal bars 204, which are substantially parallel to each other, substantially at right angles to the longitudinal sides 18 of pot shell 2, i.e. in a substantially transverse direction X of the electrolytic cell. Bars 204 are connected to each other at their ends.

(37) Each longitudinal bar 204 extends in one piece between its two ends. In other words, each longitudinal bar 204 comprises a single mechanical piece extending from one of its ends to its other end.

(38) Connecting portions 202 are advantageously located at the ends of each of longitudinal bars 204, and therefore at the ends of the ring formed by anode support 200, in such a way that they are as far removed as possible from the center of electrolytic cell 1.

(39) As shown in the figures, anode support 200 may comprise a first structure 210 designed to ensure the mechanical integrity of anode support 200 and a second structure 220 intended to carry electrolysis current from connecting portions 202 to anode block or blocks 100.

(40) First structure 210 is made of a first electrically conducting material. Second structure 220 is made of a second electrically conducting material. The second material has a substantially greater electrical conductivity than that of the first material.

(41) For example, first structure 210 is made of steel and second structure 220 is made of copper. So the first material may be steel and the second material may be copper, anode support 200 thereby comprising a steel/copper composite.

(42) First structure 210 is formed by longitudinal bars 204. Second structure 220 may be formed by additional copper bars, separate from longitudinal bars 204. The copper bars may match the shape of longitudinal bars 204.

(43) Second structure 220 is attached to first structure 210. Therefore first structure 210 supports second structure 220.

(44) First structure 210 is of an annular shape. For this purpose, longitudinal bars 204 may be a single bar bent at its ends, or separate bars attached together at their ends. Copper conducting bars 222 forming second structure 220 may also be bent to match the shape of first structure 210.

(45) Connecting electrical conductors 20 may be connected to second structure 220. As shown in FIG. 14, second structure 220 more particularly forms a plate 32 in each connecting portion 202, the plate being designed to rest against a connection surface of associated electrical connection conductor 20. A connector 30 may be used to provide a good electrical connection for anode support 200 by compressing connecting portion 202 (the plate) against the associated electrical connection conductor 20 (the connecting surface).

(46) Second structure 220 is advantageously subdivided into two separate parts 220a, 220b corresponding to two separate conduction bars 222 at a distance from each other. Part of each of conducting bars 222 at least partly forms one of two connecting portions 202.

(47) According to the embodiment in FIGS. 1 to 9, second structure 220 is located on one side of bar 204 forming first structure 210.

(48) According to the embodiment in FIGS. 10 to 13, second structure 220 is located within the ring formed by first structure 210. The second structure is therefore shorter than it would be if located on the exterior of the ring and is also protected by the first part surrounding it.

(49) More particularly, according to the embodiment in FIGS. 10 and 11, the ring formed by first structure 210 has U-shaped ends and the two conducting bars 222 or parts 220a, 220b of second structure 220 are also U-shaped, matching that of the ends of the ring formed by first structure 210. Furthermore, at ambient temperature, i.e. at a temperature of between 15 C. and 25 C., the length of the outer perimeter wall of the curved portions of the U formed by each conducting bar 222 is shorter than the length of the inner perimeter wall of the curved portions of the U formed by the corresponding end of the ring.

(50) When cold there is also a gap between conducting bars 222 and longitudinal bars 204, in particular at the curved portions of these bars.

(51) As shown in the figures, the anode assembly comprises a plurality of stubs 230 between anode support 200 and anode block or blocks 100.

(52) Each stub 230 comprises a proximal end attached to an upper face of anode block, or one of anode blocks 100, and a distal end attached to first structure 210 only. The proximal end may for example be welded to first structure 210. An electrical connection may further be made by welding between stubs 230 and second structure 220.

(53) Each stub 230 may extend in a substantially straight direction between its proximal end and its distal end, as shown in FIG. 5.

(54) Second structure 220 is advantageously attached to first structure 210 only at connecting portions 202 and/or at the distal ends of stubs 230, as illustrated in FIGS. 10 and 12.

(55) Second structure 220 is for example riveted, bolted or welded to the first structure. According to the embodiment in FIGS. 10 and 12, a plurality of attachment members 240 keeps second structure 220 attached to first structure 210.

(56) Each part 220a, 220b provides separate stubs 230 with electrical current, and the parts are distant from each other in a substantially transverse direction of the electrolytic cell.

(57) Because of this double connection on either side of the anode support it is possible to use a second discontinuous structure of two parts 220a, 220b and minimize the costs of raw material. The two parts 220a, 220b are more particularly separated by a distance corresponding to the distance between the two stubs 230 closest to the center of the anode assembly and are symmetrical in relation to plane P.

(58) Each stub 230 may comprise a single proximal end and a single distal end. In other words stubs 230 may have no cross-members or longitudinal members extending in a substantially horizontal plane.

(59) As shown in FIG. 9, the proximal end may be of one piece, with a substantially horizontal bar 240 or sealing plate extending transversely in relation to the cell and sealed within anode block 100.

(60) FIG. 15 shows another anode assembly in which such a bar 240 or sealing plate extends longitudinally in relation to the cell.

(61) As shown in FIGS. 2 to 8 and 10 to 13, anode support 200 advantageously comprises an elbowed portion 250 at each of its ends.

(62) More specifically, longitudinal bars 204 and, if applicable, conducting bars 222 may be bent in order to have an elbow portion 250 in a vertical plane at each of their ends so that the connecting portions of the anode support are located above the top surface of the stubs.

(63) The distance between the anode support and the anode block may therefore be smaller, and as a consequence so also may be the height of the stubs. Excessively high stubs would result in an increase in the potential drop, which harms the performance of the electrolytic cell, as well as an increase in the length and mass of the conducting material forming the anode support.

(64) As shown in FIGS. 2 and 11, anode support 200 may comprise at least one longitudinal reinforcing member 260 extending in a substantially transverse direction X of electrolytic cell 1 connecting the two ends of anode support 200.

(65) As shown in FIG. 12, anode support 200 may further include one or more cross-members 270, extending in a substantially longitudinal direction Y of electrolytic cell 1. Cross-member or members 270 connect the two longitudinal bars 204 together.

(66) These longitudinal members 260 and cross-members 270 may also serve as means of attachment for handling the anode assembly or the anode support.

(67) According to the embodiment in FIGS. 10 to 14 the anode assembly comprises two adjacent anode blocks 100a, 100b in a longitudinal direction Y of electrolytic cell 1. Each anode block 100a, 100b is advantageously supported by a separate longitudinal bar 204.

(68) As will be seen in the figures, the proximal end of each stub 230 may be located on a median line of the upper surface of corresponding anode block 100.

(69) Each stub 230 may for example extend in only a substantially vertical direction.

(70) According to the embodiment in FIGS. 6 to 8, the anode assembly comprises two adjacent anode blocks 100a, 100a or 100b, 100b in a longitudinal direction Y of electrolytic cell 1, and these two anode blocks 100a, 100a or 100b, 100b are borne by the same longitudinal bar 204.

(71) As shown in FIG. 8, stubs 230 may then extend obliquely or at least have a horizontal component.

(72) Still according to the embodiment in FIGS. 6 to 8, stubs 230 connecting one longitudinal bar 204 to two anode blocks 100a, 100b or 100a, 100b may be arranged in pairs. The two stubs 230 in one pair are aligned in a substantially longitudinal direction Y of the electrolytic cell 1. In other words the two stubs 230 in one pair may extend in a plane which is substantially perpendicular to a substantially transverse direction X of electrolytic cell 1.

(73) According to another aspect, the invention relates to an electrolysis plant, in particular and aluminum smelter, comprising an electrolytic cell 1 as described previously.

(74) Of course the invention is not in any way limited to the embodiment described above, this embodiment only being provided by way of example. Modifications are possible, in particular from the point of view of the constitution of the various components, or through replacement by technical equivalents, without thereby going beyond the scope of protection of the invention.