EP3347509B1 - Cathode assembly for electrolytic cell suitable for the hall-héroult process - Google Patents
Cathode assembly for electrolytic cell suitable for the hall-héroult process Download PDFInfo
- Publication number
- EP3347509B1 EP3347509B1 EP16843770.5A EP16843770A EP3347509B1 EP 3347509 B1 EP3347509 B1 EP 3347509B1 EP 16843770 A EP16843770 A EP 16843770A EP 3347509 B1 EP3347509 B1 EP 3347509B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cathode
- insert
- bar
- slot
- bore
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000009626 Hall-Héroult process Methods 0.000 title claims description 12
- 230000002093 peripheral effect Effects 0.000 claims description 25
- 239000004411 aluminium Substances 0.000 claims description 21
- 229910052782 aluminium Inorganic materials 0.000 claims description 21
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 20
- 230000004323 axial length Effects 0.000 claims description 19
- 239000004020 conductor Substances 0.000 claims description 17
- 238000005868 electrolysis reaction Methods 0.000 claims description 12
- 239000003575 carbonaceous material Substances 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 7
- 230000000712 assembly Effects 0.000 claims description 5
- 238000000429 assembly Methods 0.000 claims description 5
- 239000012811 non-conductive material Substances 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 36
- 229910052802 copper Inorganic materials 0.000 description 36
- 239000010949 copper Substances 0.000 description 36
- 229910000831 Steel Inorganic materials 0.000 description 33
- 239000010959 steel Substances 0.000 description 33
- 210000004027 cell Anatomy 0.000 description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 16
- 229910052799 carbon Inorganic materials 0.000 description 8
- 229910002804 graphite Inorganic materials 0.000 description 8
- 239000010439 graphite Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 238000007789 sealing Methods 0.000 description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 229910001018 Cast iron Inorganic materials 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000003628 erosive effect Effects 0.000 description 5
- 239000011244 liquid electrolyte Substances 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- -1 aluminium ions Chemical class 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910001610 cryolite Inorganic materials 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 125000006850 spacer group Chemical group 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 102220533938 T cell receptor beta variable 11-3_L55A_mutation Human genes 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/16—Electric current supply devices, e.g. bus bars
Definitions
- the invention relates to an improvement of an electrolysis cell (also called “pot") for producing aluminium by fused salt electrolysis using the Hall-Heroult-process. More precisely it relates to a cathode assembly for such electrolytic cell allowing to decrease the cathode voltage drop and modify the current distribution along the cathode assemblies in a desirable way.
- the invention relates to a cathode assembly in which the electrical contact between the cathode material and the busbar to which the cathode is connected involves a copper bar.
- the Hall-Heroult process is the only continuous industrial process for producing metallic aluminium form aluminium oxide.
- Aluminium oxide Al 2 O 3
- molten cryolite Na 3 AlF 6
- the resulting mixture typically at a temperature comprised between 940°C and 970°C acts as a liquid electrolyte in an electrolytic cell.
- An electrolytic cell used for the Hall-Heroult process typically comprises a steel shell (so-called “pot-shell”), a lining (comprising refractory bricks protecting said steel shell against heat, and cathode blocks usually made from graphite, anthracite or a mixture of both), and a plurality of anodes (usually made from carbon) that plunge into the liquid electrolyte.
- Anodes and cathodes are connected to external busbars.
- An electrical current is passed through the cell (typically at a voltage between 3.8 V to 5 V) which electrochemically reduces the aluminium oxide, split by the electrolyte into aluminium ions and oxygen ions, into aluminium at the cathode and oxygen at the anode, said oxygen reacting with the carbon of the anode.
- the resulting metallic aluminium is not miscible with the liquid electrolyte, has a higher density than the liquid electrolyte and will thus accumulate as a liquid metal pad on the cathode surface below the electrolyte, from where it needs to be removed from time to time, usually by suction into a crucible.
- Industrial electrolytic cells presently used for the Hall-Heroult process are generally rectangular in shape and have a length usually comprised between 8 and 25 meters and a width usually comprised between 3 and 5 meters. Most newly installed pots operate at a current intensity comprised between about 400 kA and 600 kA. They are always operated in series of several tens (up to several hundreds) pots (such a series being called a "potline"); within each series DC currents flow from one cell to the neighbouring cell. Much effort is still being made to optimise the process in order to increase its energy efficiency.
- Aluminium conductors are used for the busbar systems for both anodes and cathodes.
- aluminium cannot be used in direct contact with the cathode blocks due to its low melting point (about 660°C for pure aluminium).
- steel bars are conventionally used for ensuring electrical contact with the cathode blocks; these so-called cathode bars are connected to cathode busbars (made from aluminium) by welded and/or bolted connectors.
- Cathode bars are typically fitted into slots machined into the lower surface of the cathode block. Electrical contact between the steel bar and the carbon material of the cathode block can be direct, or the steel bar can be embedded in cast iron.
- the increase in the electrical conductivity of the cathode bars implies the use of a material having a higher electrical conductivity than steel bars. All reported solutions imply the use of inserts made from a material with a higher electrical conductivity into the cathode bar, which is usually made from steel. The material with a higher electrical conductivity is usually copper. Typical solutions comprise a copper rod or bar that is inserted into a groove or slot machined into the steel cathode bar, over all or part of the length of said cathode bar.
- FR 1 161 632 (Pechiney) discloses a copper insert fitted into a groove machined in a carbon cathode block using cast iron as a sealing material.
- the composition of cast iron used for sealing cathode bars into the grooves of carbon cathodes is known to be critical (see US 2,593,751 assigned to Pechiney), because the cast iron should not undergo any swelling due to structural transformations, as swelling could cause the carbon material to develop cracks.
- a copper bar with circular cross section fitted into a steel bar with outer rectangular cross section and an inner "U” section, the "U” section being closed by a block see US 3,551,319 (Kaiser); a copper bar welded to a lateral face of a steel bar, see US 2,846,388 (Pechiney); a copper bar with rectangular cross section inserted into a steel tube with rectangular cross sections, see US 5,976,333 (Alcoa); a copper bar with circular cross section inserted into a steel tube with rectangular external cross section and a bore with circular cross section, see WO 2005/098093 (Aluminium Pechiney).
- WO 2013/039893 (Alcoa) describes the use of a copper insert as a joint
- WO 2007/071392 (SGL Carbon) describes the use of sheets made from expanded graphite
- RU 2285754 describes the use of a carbonaceous paste.
- Such a joint material may improve the electrical contact between the carbon block and the steel bar.
- RU 2285754 proposes to secure the copper bar inserted into the slot of the steel bar by welded-on steel plates while allowing for a narrow cavity between the copper insert and the steel bar, i.e. the section of the copper insert is somewhat smaller than that of the groove into which it is fitted.
- the opposite approach is taken by WO 2009/055844 describing the use of roll bonding or explosion bonding in order to obtain an excellent contact between the copper insert and the steel bar over the whole length of the insert.
- Another problem addressed by many inventions is the connection between the copper insert and the steel cathode bar. This contact is critical for at least three reasons: the electrical contact between the copper insert and the cathode bar should be as good as possible; the thermal expansion coefficients of steel and copper are rather different and may lead to dimensional variations during the start-up of the pot; and the thermal conductivity of copper and steel is rather different, which needs to be taken into account for designing (and minimising) the heat transfer between the pot and the aluminium busbar.
- the copper inserts do not extend along the whole length of the steel cathode bar, but a spacer section is provided at each end of the cathode bar into which the copper insert does not extend.
- the copper bar can be made in two pieces separated in the centre of the cathode by a steel plug and/or an air gap.
- a steel plug and/or an air gap.
- WO 2002/42525 Servico
- a cathode bar comprising a steel bar into which at each end a copper bar is inserted, the copper insert extending beyond the end of the steel bar and ensuring the electrical contact with the connection to the aluminium busbar.
- This peak current density causes local erosion of the cathode due to magnetohydrodynamic effects which are related to high magnetic fields and lead to stirring of the molten aluminium and generalized and/or localized wear on the cathode surface that is in contact with the molten metal pad; this is particularly marked when the block is rich in graphite. Such local erosion can limit the lifetime of the cathode.
- WO 2005/98093 describes the presence of an unsealed zone at the extremity between the cathode bar and the cathode material.
- a similar solution is proposed in WO 2004/031452 (ALCAN) using embedding spacers. Fine tuning of the electrical conductivity of cathode blocks parallel to their length by using specially designed cathode bars with copper inserts can therefore decrease the localised cathode erosion; some of the cited documents also address the influence of thermal losses though cathode bars on magnetohydrodynamic effects, knowing that the use of copper inserts tends to lead to an increase of the thermal conductivity of the cathode bar.
- WO 2004/059039 describes cathode assembly in which a marginal zone of the cathode block facing the collector that has a higher electrical resistance parallel to the length of the cathode block than in the centre of the cathode block; this goal is obtained by using copper inserts or plates with different thickness over different portions of the length of the steel bar, in conjunction with electrically insulating layers between the copper bar and the steel bar.
- These cathode structures are rather difficult to manufacture and to assemble.
- cathode bar systems allow some fine-tuning of electrical conductivity at the outer face of the cathode assembly, they are rather complex to manufacture, and do not offer much flexibility as to the conductivity profile than can be achieved over the length of the cathode block.
- a cathode assembly suitable for a Hall-Heroult electrolysis cell comprising
- This cathode assembly is the first object of the present invention.
- peripheral walls of said insert define a functional clearance with the facing walls of said cathode body and/or said cathode bar, said functional clearance being filled with a solid non-conductive material or with air.
- Said electrically non-conductive region is placed inside the groove in such a way that it starts at the edge of the front wall and/or rear wall of cathode body and extends towards the centre of the cathode body.
- the non-conductive region extends over a part of the axial length of this insert, which is comprised between 6 and 20%, in particular between 9 and 15% of the whole axial length of this insert.
- the slot or bore in cathode bar has a substantially constant cross section over its axial length and the non-conductive region is defined by a local restriction of the cross section of the insert.
- the insert has a substantially constant cross section over its axial length and the non-conductive region is defined by a local widening of the cross section of the slot or bore of cathode bar.
- both the slot or bore in the cathode bar and the insert have a polygonal cross section, and at least one peripheral wall of said insert is remote from facing walls of the slot or bore in the non-conductive region.
- both the slot or bore in the cathode bar and the insert have a circular cross section, and peripheral wall of said insert is remote from facing wall of the slot or bore in the non-conductive region, so as to define an annular gap there between.
- the axial length of said second so called non-conductive region is between 50 mm and 250 mm, in particular between 100 and 200 mm.
- the insert and the slot are polygonal in cross-section, the number of walls of the insert, contacting the cathode bar, being superior in the conductive region(s) than in the non-conductive region(s).
- Another object of the invention is a process for making a cathode assembly according to the invention, comprising the steps of
- Yet another object of the invention is an electrolytic cell for the production of aluminium by the Hall-Heroult process, comprising at least one cathode assembly according to the invention.
- a last object is a process for making aluminium by the Hall-Heroult process, using an electrolysis cell having cathodes assemblies according to the invention.
- a cathode assembly comprises the cathode body 1 and the cathode bar 3.
- the present invention applies to cathodes used in the Hall-Heroult process that form the bottom of an electrolysis cell, said cathodes being assembled from individual cathode assemblies C, each of which bears at least one cathode bar 3.
- the Hall-Heroult process and the outline of an electrolysis cell are known to a person skilled in the art and will not be described here in great detail.
- the cathode assembly of the invention is designated as a whole by alphanumeric reference C. It is suitable for a Hall-Heroult electrolysis cell, but could be used in other electrolytic processes.
- the cathode assembly C first comprises a cathode body 1, of known type, which is made of a carbonaceous material, typically graphitized carbon or graphite.
- This cathode body 1 which has an elongated shape, has opposite front 11 and rear 12 walls, as well as peripheral walls. The latter are formed by parallel upper and lower walls 13 and 14, as well as parallel side walls 15 and 16.
- its length L1 (see figure 2 ) , i.e. the distance between walls 11 and 12
- W1 i.e. the distance between walls 15 and 16
- its height H1 is between about 420 mm and about 580 mm.
- the lower wall 14 of cathode body 1 is provided with a longitudinal groove 17 extending from one cathode body end to the other (see in particular figure 2 ).
- the free end of the groove 17 leads to fronts 11 or rear 12 wall of body 1.
- groove 17 Opposite side walls of groove 17 are referenced 171 and 172, whereas its upper wall is referenced 173 (see figure 3 ) .
- its width W17 i.e. the distance between walls 171 and 172, is between about 130 mm and about 280 mm.
- its depth D17 i.e. the distance between upper wall 173 and the surface of lower wall 14, is between about 150 mm and about 240 mm.
- the cathode assembly C also comprises two cathode bars 3 and 3', each of which is accommodated in groove 17.
- Each cathode bar 3 or 3' is made of a first conductive material, typically steel.
- This cathode bar 3 which has an elongated shape (see in particular figure 4 ), has opposite front 31 and rear 32 walls, as well as peripheral walls. The latter are formed by upper and lower walls 33 and 34, as well as side walls 35 and 36. Two adjacent walls form longitudinal chamfers or rounded corners 39 , in a known manner.
- upper and lower wall 33,34 and / or side walls 35,36 are parallel; in an advantageous variant of this embodiment the cathode bar is essentially rectangular in cross section.
- the length L3 of cathode bar 3 is superior to that of length of half groove 17, so as to define a projection 38 (see in particular figure 2 ), which extends beyond front wall 11 of the cathode block body.
- the length L38 of projection 38 is between about 350 mm and about 600 mm.
- the width W3 of bar 3 i.e. the distance between walls 35 and 36, is slightly inferior to the width W17 of groove 17.
- the height H3 of bar 3 i.e. the distance between walls 33 and 34, is slightly inferior to the height H17 of groove 17.
- the upper wall 33 of cathode bar 3 is provided with a housing formed by a longitudinal slot 37.
- This slot 37 extends over only a part of the whole length of the cathode bar 3, i.e. it does not longitudinally lead to front and rear walls thereof.
- this slot may be provided in another peripheral wall of cathode bar 3 , in particular in side walls 15,16 ; in this (less preferred) case a symmetrical configuration is preferred.
- Opposite side walls of slot 37 are referenced 371 and 372, whereas its bottom wall is referenced 373 (see figure 5 ).
- its width W37 i.e. the distance between walls 371 and 372
- its depth D37 i.e. the distance between walls bottom wall 373 and the surface of upper wall 33, is between about 50 mm and about 80 mm.
- the cathode assembly C also comprises two inserts 5 and 5', each of which is accommodated in a respective slot 37 and 37', see figure 9 .
- Each insert 5 or 5' is made of a second conductive material, having a higher electrical conductivity than that of said first conductive material, typically copper.
- This insert 5 which has an elongated shape, has opposite front 51 and rear 52 walls, as well as peripheral walls. The latter are formed by upper and lower walls 53 and 54, as well as side walls 55 and 56. In one embodiment upper and lower wall 53,54 and / or side walls 55,56 are parallel; in an advantageous variant of this embodiment the insert 5 is essentially rectangular in cross section.
- the above length L5 of insert 5 is called axial length, namely along main axis of this insert.
- This term "axial length” also applies for above mentioned lengths L1 and L3 .
- the peripheral length of insert i.e. the sum of the lengths of its sides, in cross section like on figures 10 and 11 .
- the peripheral contact length of insert 5 is the sum of the lengths of its sides, which contact cathode bar 3.
- the axial length L5 of insert 5 is slightly smaller to that of slot 37. Over its length, this insert comprises at least three regions, the cross-sections of which are different. In the illustrated example, this insert includes two end regions 5A and 5B, which have the same cross-section, as well as an intermediate region 5C, which has a different cross-section as will be further explained.
- the ratio L5C / L5 between the axial length L5C of intermediate region 5C and the axial length L5 of whole insert 5 is between about 8 % and about 20 %, in particular between about 9 % and about 15 %.
- the height H5 of insert i.e. the distance between walls 53 and 54, is slightly inferior to the height H37 of slot 37. This height can differ over the whole length of insert 5, related to the longitudinal deformation of the collector bar.
- the width and/or height of insert 5, i.e. the distance between walls 55 and 56, and/or between walls 53 and 54, may not be constant over this length, which defines the above mentioned different regions.
- the width W5A or W5B of end regions 5A and 5B substantially corresponds to that of slot 37. Therefore, once the insert 5 is placed into slot 37, there is a fit, first, between side wall 371 of said slot 37 and side walls 55A, 55B of said insert 5 and, moreover, between side wall 372 of said slot 37 and side walls 56A, 56B of said insert 5.
- This fit which is shown on figure 11 , makes it possible to create an electric contact between cathode bar 3 and regions 5A and 5B of the insert 5.
- side walls 55C and 56C of intermediate region 5C define recesses with side walls 55A and 56A, as well as 55B and 56B, of adjacent end regions 5A and 5B.
- these side walls 55C and 56C are distant from facing walls 371 and 372 of slot 37, in order to define two functional gaps or clearances 7 (see figure 10 ).
- These clearances are better shown on figure 12 , where their scale is enlarged towards other mechanical elements, in view of clarity.
- the width W7 of these clearances i.e. the closest distances between respective walls 371, 372 of slot 37 and intermediate region 5C, is enough to avoid any electric contact between bar 3 and insert 5, in this intermediate region. In an advantageous manner, this width is greater than about 0.5 mm, in particular greater than about 0.8 mm.
- this width W7 is between about 0.5 mm and about 2 mm, in particular between about 0.5 mm and about 1 mm.
- Figures 10 and 11 show cross sections of insert 5 accommodated in slot 37, respectively in intermediate region 5C and in end region 5B.
- the electrically conductive contact peripheral length of insert can be defined by the length of this insert contacting cathode bar 3, in cross section like on figures 10 and 11 .
- This contact may be direct, like on figure 11 , or may be indirect, i.e. it is then ensured via a conductive material.
- electrically conductive contact peripheral length is equal to the sum of the lengths of three sides of this end region 5A, i.e. H5 + W5A + H5.
- the electrically conductive surface corresponds to the product between conductive peripheral length, as defined above, and axial length. For region 5A, this conductive surface is equal to (2*H5 + W5A)*L55A.
- electrically conductive peripheral length is equal to H5+W5B+H5
- conductive surface is equal to (2*H5 + W5B)*L55B.
- the electrically conductive contact peripheral length of insert is superior in each end region, which is therefore called electrically conductive region, than in the intermediate region, which is therefore called electrically non-conductive region.
- the non-conductive region is placed inside the cathode block groove in such a way that it starts at the edge of the front wall 11 and/or rear wall 12 of cathode body 1 and extends towards the centre of the cathode body 1.
- conductive ratio i.e. the ratio between, on the one hand, electrically conductive contact surface in non-conductive region and, on the other hand, electrically conductive contact surface in conductive region. In the shown example, this ratio is approximately equal to 10 %.
- electrically conductive contact length in non-conductive region is equal to 0, since no part of region 5C contacts cathode bar 3. Facing walls respectively 54C and 373 define another clearance 7". The conductive ratio is therefore equal to 0.
- electrically conductive contact length in non-conductive region is equal to ( L54C + L56C ) .
- the conductive ratio is by far inferior to 1.
- the insert and the slot are rectangular in cross-section, i.e. they have four peripheral walls. According to some non-illustrated variants, this insert and this slot may have different polygonal cross sections, with a different number of peripheral walls. In this case, the number of walls of the insert, contacting the cathode bar, is superior in the conductive region(s) than in the non-conductive region(s).
- both the slot 37 and the insert 5 are non-polygonal, but define a portion of a circle in cross section, in particular a half circle.
- the non shown conductive region has the same radial dimension as the slot, whereas the non-conductive region is defined by a portion 5C of the insert, the radial dimension of which is reduced.
- the conductive ratio is equal to 0.
- Figures 16 to 25 show another embodiment, wherein both the insert and the slot of cathode bar are circular in cross section.
- reference numerals 2, 4 and 6 will be given respectively to cathode body, cathode bar and insert.
- the mechanical elements of cathode body 2, which are similar to those of cathode body 1 of first embodiment, will be given the same reference numerals, the first digit "2" being used instead of "1".
- the mechanical elements of cathode bar 4, which are similar to those of cathode bar 3 of first embodiment, will be given the same reference numerals, the first digit "4" being used instead of "3".
- the mechanical elements of insert 6, which are similar to those of insert 5 of first embodiment, will be given the same reference numerals, the first digit "6" being used instead of "5".
- cathode body 2 is substantially identical to that of cathode body 1.
- the structure of each cathode bar 4 or 4' is globally similar to that of cathode bar 3 or 3'.
- cathode bar 4 differs from cathode bar 3, essentially in that the housing 47 receiving the insert 6 is not formed by a slot 37, but by a bore 47. The latter does not transversally lead to a side wall of the bar 4, but longitudinally leads to the one single wall of this bar, namely rear wall 42, as can be seen on figures 19 and 22 .
- this bore 47 differs from slot 37, in that it is circular in cross-section.
- its length L47 (see figure 22 ), i.e. the distance between its bottom 473 and front wall of bar 4
- its diameter D47 is between about 30 mm and about 70 mm.
- the cathode assembly C' of this second embodiment also comprises two inserts 6 and 6', each of which is accommodated in a respective bore 47 and 47'.
- this insert 6 has an elongated shape, as well as a circular cross-section. It has opposite front 61 and rear 62 walls, as well as a peripheral wall 63.
- the axial length L6 of insert 6 can be equal to that of slot 47 . Over its length, this insert comprises at least three regions, the cross-sections of which are different. In the illustrated example, this insert includes two end regions 6A and 6B, which have the same cross-section, as well as an intermediate region 6C, which has a different cross-section as will be further explained.
- the ratio L6C / L6 between the axial length L6C of intermediate region and the axial length L6 of whole insert is between about 6 % and about 20 %, in particular between about 9 % and about 15 %.
- the diameter D6A or D6B of end regions 6A and 6B substantially corresponds to that of bore 47. Therefore, once the insert 6 is placed into bore 47, there is a fit between side wall 471 of this bore and side walls 63A, 63C of the insert (as shown on figure 23 with side wall 63A). This makes it possible to create an electric contact between bar 4 and regions 6A and 6B of the insert 6.
- the diameter D6C of intermediate region 6C is slightly inferior to the diameter D6A or D6B of end regions 6A and 6B.
- peripheral walls 63C are distant from facing walls 471 of bore 47, in order to define an annular gap or clearance 9. Said clearance 9 is better shown on figure 25 , where its scale is enlarged towards other mechanical elements, in view of clarity.
- the width W9 of this clearance 9, i.e. the closest distance between facing walls of bore 47 and intermediate region 6C, is enough to avoid any electric contact between bar 4 and insert 6, in this intermediate region. In an advantageous manner, this width is greater than about 0.5 mm, and advantageously not exceeding 2 mm. By way of example, this width W9 is between 0.5 mm and 2 mm, in particular between 0.5 mm and 1 mm.
- the conductive ratio as defined above, is equal to 0 since no region of tapered region 6C contacts the bar 4 .
- the cross section of the slot is constant and the insert has at least one local tapered region, the transversal dimension of which is smaller.
- the cross section of the insert may be constant, whereas the slot has at least one local widened region, the transversal dimension of which is larger.
- Each widened region of the slot defines a non-conductive region of the insert.
- the electrically non-conductive region 7 of the copper insert 5 can be placed inside the cathode block groove in such a way that it starts at the edge of the front wall and/or rear wall of cathode body 1 and extends towards the centre of the cathode body.
- the copper insert 5 can also extend until the outer end of the steel cathode bar 3.
- the cathode assembly C according to the present invention can be of the same height or of different height, and/or can have a structured surface, and accordingly the cathode formed by these cathode assemblies can have a single flat upper surface (which is by far the most common cathode structure), or its upper surface can comprise regions of different heights or can be otherwise structured.
- the gaps between facing walls of cathode bar 3 and groove 17 are filled with cast iron, in a known way, and/or with a carbonaceous intermediate material.
- Said intermediate carbonaceous material in direct contact with the metallic connection bar 3 must be somewhat deformable, such as to accommodate the higher thermal expansion of the metallic connection bar 3, usually made from steel, with respect to the material of the cathode assembly C.
- compressed expanded graphite most conveniently in the form of a sheet
- carbonaceous sealing paste can be used, and/or carbonaceous sealing paste.
- Compressed expanded graphite is available in the form of sheet of different densities and thickness from several manufacturers and under different tradenames (such as PapyexTM manufactured by Mersen, and SigraflexTM manufactured by SGL).
- the sealing paste advantageously includes carbonaceous particles dispersed in a binder that has a high carbon yield after baking.
- Said carbonaceous particles can be graphite particles.
- Such sealing pastes are commercially available from different manufacturers and under various tradenames (Sealing paste HCF 80 from Carbone Savoie for example).
- the thickness of the sealing paste is calculated according to the width of the collector bar, taking into consideration the differential of thermal expansions between the copper and the graphitized cathode assembly; a thickness comprised between 15 and 25 mm can be used.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Description
- The invention relates to an improvement of an electrolysis cell (also called "pot") for producing aluminium by fused salt electrolysis using the Hall-Heroult-process. More precisely it relates to a cathode assembly for such electrolytic cell allowing to decrease the cathode voltage drop and modify the current distribution along the cathode assemblies in a desirable way.
- In particular, the invention relates to a cathode assembly in which the electrical contact between the cathode material and the busbar to which the cathode is connected involves a copper bar.
- The Hall-Heroult process is the only continuous industrial process for producing metallic aluminium form aluminium oxide. Aluminium oxide (Al2O3) is dissolved in molten cryolite (Na3AlF6), and the resulting mixture (typically at a temperature comprised between 940°C and 970°C) acts as a liquid electrolyte in an electrolytic cell. An electrolytic cell (also called "pot") used for the Hall-Heroult process typically comprises a steel shell (so-called "pot-shell"), a lining (comprising refractory bricks protecting said steel shell against heat, and cathode blocks usually made from graphite, anthracite or a mixture of both), and a plurality of anodes (usually made from carbon) that plunge into the liquid electrolyte. Anodes and cathodes are connected to external busbars. An electrical current is passed through the cell (typically at a voltage between 3.8 V to 5 V) which electrochemically reduces the aluminium oxide, split by the electrolyte into aluminium ions and oxygen ions, into aluminium at the cathode and oxygen at the anode, said oxygen reacting with the carbon of the anode. The resulting metallic aluminium is not miscible with the liquid electrolyte, has a higher density than the liquid electrolyte and will thus accumulate as a liquid metal pad on the cathode surface below the electrolyte, from where it needs to be removed from time to time, usually by suction into a crucible.
- The electrical energy is a major operational cost in the Hall-Heroult process. Capital cost is an important issue, too. Ever since the invention of the process at the end of the 19th century much effort has been undertaken to improve the energy efficiency (expressed in kW/h per kg or ton of aluminium), and there has also be a trend to increase the size of the pots and the current intensity at which they are operated in order to increase the plant productivity and bring down the capital cost per unit of aluminium produced in the plant.
- Industrial electrolytic cells presently used for the Hall-Heroult process are generally rectangular in shape and have a length usually comprised between 8 and 25 meters and a width usually comprised between 3 and 5 meters. Most newly installed pots operate at a current intensity comprised between about 400 kA and 600 kA. They are always operated in series of several tens (up to several hundreds) pots (such a series being called a "potline"); within each series DC currents flow from one cell to the neighbouring cell. Much effort is still being made to optimise the process in order to increase its energy efficiency.
- The passage of the enormous current intensities through the electrolytic cell leads to ohmic losses at various locations of the pot. Aluminium conductors are used for the busbar systems for both anodes and cathodes. However, aluminium cannot be used in direct contact with the cathode blocks due to its low melting point (about 660°C for pure aluminium). As a consequence, steel bars are conventionally used for ensuring electrical contact with the cathode blocks; these so-called cathode bars are connected to cathode busbars (made from aluminium) by welded and/or bolted connectors. Cathode bars are typically fitted into slots machined into the lower surface of the cathode block. Electrical contact between the steel bar and the carbon material of the cathode block can be direct, or the steel bar can be embedded in cast iron.
- During the past decades, much effort has been devoted to the decrease of ohmic losses in cathode bars. Most inventions reported in prior art patents focus on the intrinsic conductivity of the steel cathode bar, or on the contact resistance between the cathode bar and the cathode block or between the cathode bar and the aluminium busbar.
- The increase in the electrical conductivity of the cathode bars implies the use of a material having a higher electrical conductivity than steel bars. All reported solutions imply the use of inserts made from a material with a higher electrical conductivity into the cathode bar, which is usually made from steel. The material with a higher electrical conductivity is usually copper. Typical solutions comprise a copper rod or bar that is inserted into a groove or slot machined into the steel cathode bar, over all or part of the length of said cathode bar. The basic concept of a copper insert fitted into a slot or groove machined in a steel cathode bar is described in
WO 2001/63014 WO 2005/098093 (Aluminium Pechiney) andWO 2009/055844 (BHB Billington). -
FR 1 161 632US 2,593,751 assigned to Pechiney), because the cast iron should not undergo any swelling due to structural transformations, as swelling could cause the carbon material to develop cracks. - A large number of more specific embodiments have been described for these copper inserts, such as: A copper bar with circular cross section fitted into a steel bar with outer rectangular cross section and an inner "U" section, the "U" section being closed by a block, see
US 3,551,319 (Kaiser); a copper bar welded to a lateral face of a steel bar, seeUS 2,846,388 (Pechiney); a copper bar with rectangular cross section inserted into a steel tube with rectangular cross sections, seeUS 5,976,333 (Alcoa); a copper bar with circular cross section inserted into a steel tube with rectangular external cross section and a bore with circular cross section, seeWO 2005/098093 (Aluminium Pechiney). - Several documents disclose the use of a joint material present between the cathode material and the steel bar:
WO 2013/039893 (Alcoa) describes the use of a copper insert as a joint,WO 2007/071392 (SGL Carbon) describes the use of sheets made from expanded graphite, andRU 2285754 RU 2285754 WO 2009/055844 describing the use of roll bonding or explosion bonding in order to obtain an excellent contact between the copper insert and the steel bar over the whole length of the insert. - Another problem addressed by many inventions is the connection between the copper insert and the steel cathode bar. This contact is critical for at least three reasons: the electrical contact between the copper insert and the cathode bar should be as good as possible; the thermal expansion coefficients of steel and copper are rather different and may lead to dimensional variations during the start-up of the pot; and the thermal conductivity of copper and steel is rather different, which needs to be taken into account for designing (and minimising) the heat transfer between the pot and the aluminium busbar. For this reason, in some prior art embodiments the copper inserts do not extend along the whole length of the steel cathode bar, but a spacer section is provided at each end of the cathode bar into which the copper insert does not extend. Also, the copper bar can be made in two pieces separated in the centre of the cathode by a steel plug and/or an air gap. Such a structure is described in
US 6,387,237 andUS 6,231,745 (Alcoa). The opposite approach is proposed byWO 2002/42525 - As can be seen, there has been a wealth of different designs of copper inserts in cathode bars.
- In addition to the goal to decrease ohmic losses, the insertion of copper bars of complex shape into cathode bars has been used to fine-tune the current distribution over the length of the cathode bar. In fact, changes to the properties of cathode blocks have led to the emergence of new problems such as, for example, erosion of cathodes. For example, it has been observed that as the graphite content of cathode blocks increases, a block becomes more sensitive to erosion problems at the head of the block. In fact, the current density is not distributed uniformly over the entire width of the pot, and there is a peak current density at each end of the block, on the surface of the cathode. This peak current density causes local erosion of the cathode due to magnetohydrodynamic effects which are related to high magnetic fields and lead to stirring of the molten aluminium and generalized and/or localized wear on the cathode surface that is in contact with the molten metal pad; this is particularly marked when the block is rich in graphite. Such local erosion can limit the lifetime of the cathode. These phenomena are well known in the art (see for a review: Sørlie and Øye, "Cathodes in Aluminium Electrolysis", 3rd edition (2010), in particular p.205-209 and p.527-550). In order to decrease this effect,
WO 2005/98093 WO 2004/031452 (ALCAN) using embedding spacers. Fine tuning of the electrical conductivity of cathode blocks parallel to their length by using specially designed cathode bars with copper inserts can therefore decrease the localised cathode erosion; some of the cited documents also address the influence of thermal losses though cathode bars on magnetohydrodynamic effects, knowing that the use of copper inserts tends to lead to an increase of the thermal conductivity of the cathode bar. -
WO 2004/059039 (SGL) describes cathode assembly in which a marginal zone of the cathode block facing the collector that has a higher electrical resistance parallel to the length of the cathode block than in the centre of the cathode block; this goal is obtained by using copper inserts or plates with different thickness over different portions of the length of the steel bar, in conjunction with electrically insulating layers between the copper bar and the steel bar. These cathode structures are rather difficult to manufacture and to assemble. - A similar effect is achieved in a simpler way by a copper insert that ends at a specified distance from the outer face of the cathode block, as described in
WO 2008/062318 (Rio Tinto Alcan). Another system aiming to achieve the same effect isWO 03/014423 US 6,231,745 (Alcoa) describes a half-length copper insert that extends somewhat out of the cathode block, but does not extend outside the cell wall. - While these cathode bar systems allow some fine-tuning of electrical conductivity at the outer face of the cathode assembly, they are rather complex to manufacture, and do not offer much flexibility as to the conductivity profile than can be achieved over the length of the cathode block.
- It is the objective of the present invention to come up with a new design of cathode bars that decreases ohmic losses and that allows flexible fine tuning of electrical conductivity of the cathode assembly along its length, and that is simple to manufacture.
- According to the invention, the problem is solved by a cathode assembly suitable for a Hall-Heroult electrolysis cell, comprising
- a cathode body made of a carbonaceous material;
- at least one cathode bar made of a first conductive material, said cathode bar being fitted in a groove provided in said cathode body;
- at least an insert made of a second conductive material, having a higher electrical conductivity than that of said first conductive material, said insert being fitted in a slot provided in said cathode bar;
- This cathode assembly is the first object of the present invention.
- In an embodiment, in the non-conductive region, peripheral walls of said insert define a functional clearance with the facing walls of said cathode body and/or said cathode bar, said functional clearance being filled with a solid non-conductive material or with air.
- Said electrically non-conductive region is placed inside the groove in such a way that it starts at the edge of the front wall and/or rear wall of cathode body and extends towards the centre of the cathode body.
- In an embodiment, the non-conductive region extends over a part of the axial length of this insert, which is comprised between 6 and 20%, in particular between 9 and 15% of the whole axial length of this insert.
- In another embodiment, the slot or bore in cathode bar has a substantially constant cross section over its axial length and the non-conductive region is defined by a local restriction of the cross section of the insert.
- In yet another embodiment, the insert has a substantially constant cross section over its axial length and the non-conductive region is defined by a local widening of the cross section of the slot or bore of cathode bar.
- In yet another embodiment, both the slot or bore in the cathode bar and the insert have a polygonal cross section, and at least one peripheral wall of said insert is remote from facing walls of the slot or bore in the non-conductive region.
- In yet another embodiment both the slot or bore in the cathode bar and the insert have a circular cross section, and peripheral wall of said insert is remote from facing wall of the slot or bore in the non-conductive region, so as to define an annular gap there between.
- In all embodiments, advantageously, the axial length of said second so called non-conductive region is between 50 mm and 250 mm, in particular between 100 and 200 mm.
- In another embodiment, the insert and the slot are polygonal in cross-section, the number of walls of the insert, contacting the cathode bar, being superior in the conductive region(s) than in the non-conductive region(s).
- Another object of the invention is a process for making a cathode assembly according to the invention, comprising the steps of
- a) providing a cathode body made of a carbonaceous material;
- b) providing a groove or bore in said cathode body;
- c) providing at least one cathode bar made of a first conductive material,
- d) providing a slot or bore in said cathode bar,
- e) providing at least one insert made of a second conductive material, having a higher electrical conductivity than that of said first conductive material, said insert being fitted in a slot or bore provided in said cathode bar;
- f) providing at least one cathode bar being fitted in said groove or bore provided in said cathode body;
- Yet another object of the invention is an electrolytic cell for the production of aluminium by the Hall-Heroult process, comprising at least one cathode assembly according to the invention.
- A last object is a process for making aluminium by the Hall-Heroult process, using an electrolysis cell having cathodes assemblies according to the invention.
-
-
Figures 1 to 26 represent various embodiments of the present invention. -
Figure 1 is a perspective view, showing a first embodiment of a cathode assembly according to the invention, wherein the insert of this assembly is rectangular in cross section. -
Figure 2 is a bottom view, showing the cathode assembly offigure 1 . -
Figure 3 is a cross section showing the cathode assembly offigure 1 , along line III-III offigure 2 . -
Figure 4 is a perspective view, showing a cathode bar which belongs to the cathode assembly of thefigure 1 . -
Figure 5 is a cross section showing the cathode bar offigure 4 , along line V-V offigure 4 . -
Figure 6 is a perspective view, showing an insert which belongs to the cathode assembly of thefigure 1 . -
Figures 7 and 8 are cross sections showing the insert offigure 6 , along lines respectively VII-VII and VIII-VIII offigure 6 . -
Figure 9 is a perspective view, showing the insert offigure 6 which is fitted in a slot of the cathode bar offigure 4 . -
Figures 10 and 11 are cross sections showing the insert fitted in the slot of the cathode bar, along lines respectively X-X and XI-XI offigure 9 . -
Figure 12 is a view at a larger scale, showing the detail XII offigure 10 . -
Figures 13 to 15 are cross sections analogous tofigure 12 , showing variants of this first embodiment the invention. -
Figure 16 is a perspective view, analogous tofigure 1 , showing a second embodiment of a cathode assembly according to the invention, wherein the insert of this assembly is circular in cross section. -
Figure 17 is a bottom view, analogous tofigure 2 , showing the cathode assembly offigure 16 . -
Figure 18 is a cross section showing the cathode assembly offigure 1 , along line XVIII-XVIII offigure 17 . -
Figure 19 is a perspective view, analogous tofigure 6 , showing a cathode bar which belongs to the cathode assembly of thefigure 16 . -
Figure 20 is a cross section showing the cathode bar offigure 19 , along line XX-XX offigure 19 . -
Figure 21 is a perspective view, analogous tofigure 6 , showing an insert which belongs to the cathode assembly of thefigure 16 . -
Figure 22 is a bottom view, showing the insert offigure 21 which is fitted in a hole of the cathode bar offigure 4 . -
Figures 23 and 24 are cross sections showing the insert fitted in the hole of the cathode bar, along line XXIII-XXIII and line XXIV-XXIV, respectively, offigure 22 . -
Figure 25 is an enlarged view, showing the detail XXV offigure 24 . -
Figure 26 is a cross section of a cathode assembly along a vertical longitudinal plane, showing more specifically the end regions of the insert and the cathode body. - The followina reference signs are used on the figures:
1,2 Cathode body 171, 172 Side walls of groove 17 3,3',4,4' Cathode bar 173 Bottom wall of groove 17 5,5',6,6' Insert (bar) 371,372 Side walls of slot 37 5A,5B End regions of insert 5 373 Bottom of slot 37 5C Intermediate region of insert 5 C Cathode block 7 Clearance 11,12 Front / rear wall of cathode body 1 13,14 Upper / lower wall of cathode body 1 51,52 Front / rear wall of insert 5 15,16 Side walls of cathode body 1 53,54 Upper / lower wall of insert 5 17 Longitudinal groove in cathode body 1 54A,54B Lower wall of insert 5 (end regions) 31,32 Front / rear wall of cathode bar 3 55,56 Side walls of insert 5 33,34 Upper / lower wall of cathode bar 3 55A,55B Side walls of insert 5 (end regions) 35,36 Side walls of cathode bar 3 55C Side wall of insert 5 (intermediate) 37,37' Slot forming housing 56A,56B Side walls of insert 5 (end regions) 38 Projection 39 Chamfer DX Depth of element X : D37 HX Height of element X : H1, H3, H5, H37 LX Length of element X : L3, L5, L5C, L38 WX Width of element W: W1, W3, W51, W5A, W5B, W7, W17, W37 - In the present description, the terms "upper" and "lower" refer to a cathode block in use, lying on a horizontal ground surface. Moreover, unless specific contrary indication, "conductive" means "electrically conductive".
According to the terminology used in the present description and in the art, a "cathode assembly" C comprises thecathode body 1 and thecathode bar 3. - The present invention applies to cathodes used in the Hall-Heroult process that form the bottom of an electrolysis cell, said cathodes being assembled from individual cathode assemblies C, each of which bears at least one
cathode bar 3. The Hall-Heroult process and the outline of an electrolysis cell (also called "pot") are known to a person skilled in the art and will not be described here in great detail. - The cathode assembly of the invention is designated as a whole by alphanumeric reference C. It is suitable for a Hall-Heroult electrolysis cell, but could be used in other electrolytic processes.
- The cathode assembly C first comprises a
cathode body 1, of known type, which is made of a carbonaceous material, typically graphitized carbon or graphite. Thiscathode body 1, which has an elongated shape, hasopposite front 11 and rear 12 walls, as well as peripheral walls. The latter are formed by parallel upper andlower walls parallel side walls figure 2 ), i.e. the distance betweenwalls figure 2 ), i.e. the distance betweenwalls figure 1 ), i.e. the distance betweenwalls - The
lower wall 14 ofcathode body 1 is provided with alongitudinal groove 17 extending from one cathode body end to the other (see in particularfigure 2 ). The free end of thegroove 17 leads tofronts 11 or rear 12 wall ofbody 1. - The structure of
groove 17 will now be described. Opposite side walls ofgroove 17 are referenced 171 and 172, whereas its upper wall is referenced 173 (seefigure 3 ). By way of example, its width W17, i.e. the distance betweenwalls upper wall 173 and the surface oflower wall 14, is between about 150 mm and about 240 mm. - The cathode assembly C also comprises two
cathode bars 3 and 3', each of which is accommodated ingroove 17. Eachcathode bar 3 or 3' is made of a first conductive material, typically steel. The structure ofbar 3 will now be described, bearing in mind that structure of the other bar 3' is identical. Thiscathode bar 3, which has an elongated shape (see in particularfigure 4 ), hasopposite front 31 and rear 32 walls, as well as peripheral walls. The latter are formed by upper andlower walls side walls rounded corners 39, in a known manner. In one embodiment upper andlower wall side walls - The length L3 of
cathode bar 3 is superior to that of length ofhalf groove 17, so as to define a projection 38 (see in particularfigure 2 ), which extends beyondfront wall 11 of the cathode block body. By way of example, the length L38 ofprojection 38 is between about 350 mm and about 600 mm. Moreover the width W3 ofbar 3, i.e. the distance betweenwalls groove 17. Finally the height H3 ofbar 3, i.e. the distance betweenwalls groove 17. During manufacture, the gaps between facing walls ofbar 3 and groove 17 are filled with cast iron, in a known way, and/or with an intermediate carbonaceous material (seefigure 3 ) which will be described below. - Turning back to
figure 4 , theupper wall 33 ofcathode bar 3 is provided with a housing formed by alongitudinal slot 37. Thisslot 37 extends over only a part of the whole length of thecathode bar 3, i.e. it does not longitudinally lead to front and rear walls thereof. As a variant, this slot may be provided in another peripheral wall ofcathode bar 3, in particular inside walls slot 37 are referenced 371 and 372, whereas its bottom wall is referenced 373 (seefigure 5 ). By way of example, its width W37, i.e. the distance betweenwalls bottom wall 373 and the surface ofupper wall 33, is between about 50 mm and about 80 mm. - The cathode assembly C also comprises two
inserts 5 and 5', each of which is accommodated in arespective slot 37 and 37', seefigure 9 . Eachinsert 5 or 5' is made of a second conductive material, having a higher electrical conductivity than that of said first conductive material, typically copper. The structure ofinsert 5 will now be described, bearing in mind that structure of the other insert 5' is identical. Referring tofigures 6 to 8 , thisinsert 5, which has an elongated shape, hasopposite front 51 and rear 52 walls, as well as peripheral walls. The latter are formed by upper andlower walls side walls lower wall side walls insert 5 is essentially rectangular in cross section. - The above length L5 of
insert 5 is called axial length, namely along main axis of this insert. This term "axial length" also applies for above mentioned lengths L1 and L3. Let us also define the peripheral length of insert, i.e. the sum of the lengths of its sides, in cross section like onfigures 10 and 11 . As will be more precisely defined hereafter, the peripheral contact length ofinsert 5 is the sum of the lengths of its sides, whichcontact cathode bar 3. - For allowing the insert to expand inside the slot the axial length L5 of
insert 5 is slightly smaller to that ofslot 37. Over its length, this insert comprises at least three regions, the cross-sections of which are different. In the illustrated example, this insert includes twoend regions intermediate region 5C, which has a different cross-section as will be further explained. The ratio L5C/L5 between the axial length L5C ofintermediate region 5C and the axial length L5 ofwhole insert 5 is between about 8 % and about 20 %, in particular between about 9 % and about 15 %. - The height H5 of insert, i.e. the distance between
walls slot 37. This height can differ over the whole length ofinsert 5, related to the longitudinal deformation of the collector bar. On the other hand, the width and/or height ofinsert 5, i.e. the distance betweenwalls walls - The width W5A or W5B of
end regions slot 37. Therefore, once theinsert 5 is placed intoslot 37, there is a fit, first, betweenside wall 371 of saidslot 37 andside walls insert 5 and, moreover, betweenside wall 372 of saidslot 37 andside walls insert 5. This fit, which is shown onfigure 11 , makes it possible to create an electric contact betweencathode bar 3 andregions insert 5. - On the other hand,
side walls intermediate region 5C define recesses withside walls adjacent end regions side walls walls slot 37, in order to define two functional gaps or clearances 7 (seefigure 10 ). These clearances are better shown onfigure 12 , where their scale is enlarged towards other mechanical elements, in view of clarity. The width W7 of these clearances, i.e. the closest distances betweenrespective walls slot 37 andintermediate region 5C, is enough to avoid any electric contact betweenbar 3 andinsert 5, in this intermediate region. In an advantageous manner, this width is greater than about 0.5 mm, in particular greater than about 0.8 mm. By way of example, this width W7 is between about 0.5 mm and about 2 mm, in particular between about 0.5 mm and about 1 mm. -
Figures 10 and 11 show cross sections ofinsert 5 accommodated inslot 37, respectively inintermediate region 5C and inend region 5B. On these figures, as previously mentioned, the electrically conductive contact peripheral length of insert can be defined by the length of this insert contactingcathode bar 3, in cross section like onfigures 10 and 11 . This contact may be direct, like onfigure 11 , or may be indirect, i.e. it is then ensured via a conductive material. - As shown on
figure 11 ,side walls end region 5A, i.e. H5 + W5A + H5. The electrically conductive surface corresponds to the product between conductive peripheral length, as defined above, and axial length. Forregion 5A, this conductive surface is equal to (2*H5 + W5A)*L55A. In an analogous manner, forregion 5B, electrically conductive peripheral length is equal to H5+W5B+H5, and conductive surface is equal to (2*H5 + W5B)*L55B. - On the other hand, as shown on
figure 10 , onlylower wall 54C contacts the cathode bar, but the contact between insert and collector bar is not good enough to allow the current to flow. Electrically conductive peripheral length ofregion 5C is therefore at most equal to W5C and, in any case, far inferior to electrically conductive distance inother regions surface 54C compared to the contact surface inzone - As explained in the above paragraph, the electrically conductive contact peripheral length of insert is superior in each end region, which is therefore called electrically conductive region, than in the intermediate region, which is therefore called electrically non-conductive region. This makes it possible to tailor the electrical conductivity of the
cathode bar 3, and more generally the electrical conductivity of the cathode assembly C, parallel to its length, by an appropriate choice of the different parameters indicated above. Tailoring the electrical conductivity of the cathode assembly C allows to modify the magnetic fields in the electrolysis cell that keep the molten metal in movement, and allows eventually to modify the magnetohydrodynamics of the electrolysis cell. - The non-conductive region is placed inside the cathode block groove in such a way that it starts at the edge of the
front wall 11 and/orrear wall 12 ofcathode body 1 and extends towards the centre of thecathode body 1. - Let us define the so-called conductive ratio, i.e. the ratio between, on the one hand, electrically conductive contact surface in non-conductive region and, on the other hand, electrically conductive contact surface in conductive region. In the shown example, this ratio is approximately equal to 10 %.
- As a first variant, shown in
figure 13 , electrically conductive contact length in non-conductive region is equal to 0, since no part ofregion 5Ccontacts cathode bar 3. Facing walls respectively 54C and 373 define anotherclearance 7". The conductive ratio is therefore equal to 0. - As another variant, shown in
figure 14 , electrically conductive contact length in non-conductive region is equal to (L54C+L56C). There is only onesingle clearance 7, betweenwall 55C andcathode bar 3. The conductive ratio is by far inferior to 1. - In the first shown embodiment, the insert and the slot are rectangular in cross-section, i.e. they have four peripheral walls. According to some non-illustrated variants, this insert and this slot may have different polygonal cross sections, with a different number of peripheral walls. In this case, the number of walls of the insert, contacting the cathode bar, is superior in the conductive region(s) than in the non-conductive region(s).
- According to another variant, shown on
figure 15 , both theslot 37 and theinsert 5 are non-polygonal, but define a portion of a circle in cross section, in particular a half circle. In this case, the non shown conductive region has the same radial dimension as the slot, whereas the non-conductive region is defined by aportion 5C of the insert, the radial dimension of which is reduced. In this non-conductive region, there is substantially no contact between the insert and the facing wall of the slot, which defines aclearance 7 which leads onupper wall 33. In this variant, the conductive ratio is equal to 0. -
Figures 16 to 25 show another embodiment, wherein both the insert and the slot of cathode bar are circular in cross section. Hereafter,reference numerals cathode body 2, which are similar to those ofcathode body 1 of first embodiment, will be given the same reference numerals, the first digit "2" being used instead of "1". The mechanical elements ofcathode bar 4, which are similar to those ofcathode bar 3 of first embodiment, will be given the same reference numerals, the first digit "4" being used instead of "3". The mechanical elements ofinsert 6, which are similar to those ofinsert 5 of first embodiment, will be given the same reference numerals, the first digit "6" being used instead of "5". - The structure of
cathode body 2 is substantially identical to that ofcathode body 1. The structure of eachcathode bar 4 or 4' is globally similar to that ofcathode bar 3 or 3'. However,cathode bar 4 differs fromcathode bar 3, essentially in that thehousing 47 receiving theinsert 6 is not formed by aslot 37, but by abore 47. The latter does not transversally lead to a side wall of thebar 4, but longitudinally leads to the one single wall of this bar, namelyrear wall 42, as can be seen onfigures 19 and22 . Moreover this bore 47 differs fromslot 37, in that it is circular in cross-section. By way of example, its length L47 (seefigure 22 ), i.e. the distance between its bottom 473 and front wall ofbar 4, is between about 1000 mm and about 1750 mm. By way of example, its diameter D47 (seefigure 20 ) is between about 30 mm and about 70 mm. - The cathode assembly C' of this second embodiment also comprises two
inserts 6 and 6', each of which is accommodated in arespective bore 47 and 47'. Referring tofigure 21 , thisinsert 6 has an elongated shape, as well as a circular cross-section. It hasopposite front 61 and rear 62 walls, as well as aperipheral wall 63. - The axial length L6 of
insert 6 can be equal to that ofslot 47. Over its length, this insert comprises at least three regions, the cross-sections of which are different. In the illustrated example, this insert includes twoend regions intermediate region 6C, which has a different cross-section as will be further explained. The ratio L6C/L6 between the axial length L6C of intermediate region and the axial length L6 of whole insert is between about 6 % and about 20 %, in particular between about 9 % and about 15 %. - The diameter D6A or D6B of
end regions bore 47. Therefore, once theinsert 6 is placed intobore 47, there is a fit betweenside wall 471 of this bore andside walls figure 23 withside wall 63A). This makes it possible to create an electric contact betweenbar 4 andregions insert 6. On the other hand, the diameter D6C ofintermediate region 6C is slightly inferior to the diameter D6A or D6B ofend regions - In other words,
peripheral walls 63C are distant from facingwalls 471 ofbore 47, in order to define an annular gap orclearance 9. Saidclearance 9 is better shown onfigure 25 , where its scale is enlarged towards other mechanical elements, in view of clarity. The width W9 of thisclearance 9, i.e. the closest distance between facing walls ofbore 47 andintermediate region 6C, is enough to avoid any electric contact betweenbar 4 andinsert 6, in this intermediate region. In an advantageous manner, this width is greater than about 0.5 mm, and advantageously not exceeding 2 mm. By way of example, this width W9 is between 0.5 mm and 2 mm, in particular between 0.5 mm and 1 mm. In this embodiment, the conductive ratio, as defined above, is equal to 0 since no region oftapered region 6C contacts thebar 4. - In the above shown and non-shown embodiments, the cross section of the slot is constant and the insert has at least one local tapered region, the transversal dimension of which is smaller. As a variant, the cross section of the insert may be constant, whereas the slot has at least one local widened region, the transversal dimension of which is larger. Each widened region of the slot defines a non-conductive region of the insert.
- As shown on
figure 26 , the electricallynon-conductive region 7 of thecopper insert 5 can be placed inside the cathode block groove in such a way that it starts at the edge of the front wall and/or rear wall ofcathode body 1 and extends towards the centre of the cathode body. - It should be noted the
copper insert 5 can also extend until the outer end of thesteel cathode bar 3. - The cathode assembly C according to the present invention can be of the same height or of different height, and/or can have a structured surface, and accordingly the cathode formed by these cathode assemblies can have a single flat upper surface (which is by far the most common cathode structure), or its upper surface can comprise regions of different heights or can be otherwise structured.
- As mentioned above, during manufacture, the gaps between facing walls of
cathode bar 3 and groove 17 are filled with cast iron, in a known way, and/or with a carbonaceous intermediate material. Said intermediate carbonaceous material in direct contact with themetallic connection bar 3 must be somewhat deformable, such as to accommodate the higher thermal expansion of themetallic connection bar 3, usually made from steel, with respect to the material of the cathode assembly C. As an intermediate carbonaceous material in direct contact with thecathode bar 3 and the cathode assembly C, compressed expanded graphite (most conveniently in the form of a sheet) can be used, and/or carbonaceous sealing paste. - Compressed expanded graphite is available in the form of sheet of different densities and thickness from several manufacturers and under different tradenames (such as Papyex™ manufactured by Mersen, and Sigraflex™ manufactured by SGL).
- Concerning the carbonaceous sealing paste, the sealing paste advantageously includes carbonaceous particles dispersed in a binder that has a high carbon yield after baking. Said carbonaceous particles can be graphite particles. Such sealing pastes are commercially available from different manufacturers and under various tradenames (Sealing paste HCF 80 from Carbone Savoie for example). The thickness of the sealing paste is calculated according to the width of the collector bar, taking into consideration the differential of thermal expansions between the copper and the graphitized cathode assembly; a thickness comprised between 15 and 25 mm can be used.
Claims (13)
- A cathode assembly (C) suitable for a Hall-Heroult electrolysis cell, comprising- a cathode body (1,2) made of a carbonaceous material;- at least one cathode bar (3,3',4,4') made of a first conductive material, said cathode bar (3,3',4,4') being fitted in a groove (17) provided in said cathode body (1,2);- at least an insert (5,5',6,6') made of a second conductive material, having a higher electrical conductivity than that of said first conductive material, said insert (5,5',6,6') being fitted in a slot or bore (37) provided in said cathode bar (3,3',4,4');characterized in that said insert (5,5',6,6') has at least one first so-called electrically conductive region and at least one second so-called electrically non-conductive region, the electrically conductive contact peripheral length of said insert with said cathode body (1,2) and/or said cathode bar (3,3',4,4') being superior in the first region than in the second region, the peripheral contact length of the insert being the sum of the lengths of its sides, in cross section, which contact the cathode bar and/or the cathode body.
- A cathode assembly (C) according to claim 1, characterized in that, in the non-conductive region, peripheral walls of said insert define a functional clearance with the facing walls of said body (1,2) and/or said cathode bar (3,3',4,4'), said functional clearance being filled with a solid non-conductive material or with air.
- A cathode assembly (C) according to claim 1 or 2, characterized in that said electrically non-conductive region is placed inside the groove in such a way that it starts at the edge of the front wall and/or rear wall of cathode body (1,2) and extends towards the centre of the cathode body.
- A cathode assembly (C) according to any of claims 1 to 3, characterized in that the non-conductive region extends over a part of the axial length of this insert, which is comprised between 6 and 20%, in particular between 9 and 15% of the whole axial length of this insert.
- A cathode assembly (C) according to any of claims 1 to 4, characterized in that the slot or bore (37) in cathode bar (3,3',4,4') has a substantially constant cross section over its axial length and the non-conductive region is defined by a local restriction of the cross section of the insert (5,5',6,6').
- A cathode assembly (C) according to any of claims 1 to 4, characterized in that the insert (5,5',6,6') has a substantially constant cross section over its axial length and the non-conductive region is defined by a local widening of the cross section of the slot or bore (37) of cathode bar (3,3',4,4').
- A cathode assembly (C) according to any of claims 1 to 6, characterized in that both the slot or bore (37) in the cathode bar (3,3',4,4') and the insert (5,5',6,6') have a polygonal cross section, and at least one peripheral wall of said insert is remote from facing walls of the slot or bore in the non-conductive region.
- A cathode assembly (C) according to any of claims 1 to 6, characterized in that both the slot or bore (37) in the cathode bar (3,3',4,4') and the insert (5,5',6,6') have a circular cross section, and peripheral wall of said insert is remote from facing wall of the slot or bore in the non-conductive region, so as to define an annular gap there between.
- A cathode assembly (C) according to any of claims 1 to 8, characterized in that the axial length of said second so called non-conductive region is between 50 mm and 250 mm, in particular between 100 and 200 mm.
- A cathode assembly (C) according to any of claims 1 to 9, characterized in that the insert (5,5',6,6') and the slot (37) are polygonal in cross-section, the number of walls of the insert, contacting the cathode bar (3,3',4,4'), being superior in the conductive region(s) than in the non-conductive region(s).
- A process for making a cathode assembly (C) according to any of claims 1 to 10, comprising the steps ofa) providing a cathode body (1,2) made of a carbonaceous material;b) providing a groove or bore (17) in said cathode body;c) providing at least one cathode bar (3,3',4,4') made of a first conductive material,d) providing a slot or bore (37) in said cathode bar (3,3',4,4'),e) providing at least one insert (5,5',6,6') made of a second conductive material, having a higher electrical conductivity than that of said first conductive material, said insert being fitted in a slot or bore (37) provided in said cathode bar (3,3',4,4');f) providing at least one cathode bar being fitted in said groove or bore (17) provided in said cathode body (1,2);wherein said insert (5,5',6,6') has at least one first so-called electrically conductive region and at least one second so-called electrically non-conductive region, the electrically conductive contact length, in cross section, of said insert with said body and/or said cathode bar being superior in the first region than in the second region.
- Electrolytic cell for the production of aluminium by the Hall-Heroult process, comprising at least one cathode assembly (C) according to any of claim 1 to 10.
- A process for making aluminium by the Hall-Heroult process, using an electrolysis cell having cathode assemblies (C) according to any of claims 1 to 10.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1515963.5A GB2542150A (en) | 2015-09-09 | 2015-09-09 | Cathode assembly for electrolytic cell suitable for the Hall-Héroult process |
PCT/IB2016/055324 WO2017042691A1 (en) | 2015-09-09 | 2016-09-07 | Cathode assembly for electrolytic cell suitable for the hall-héroult process |
Publications (3)
Publication Number | Publication Date |
---|---|
EP3347509A1 EP3347509A1 (en) | 2018-07-18 |
EP3347509A4 EP3347509A4 (en) | 2019-05-01 |
EP3347509B1 true EP3347509B1 (en) | 2020-08-05 |
Family
ID=54345988
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16843770.5A Active EP3347509B1 (en) | 2015-09-09 | 2016-09-07 | Cathode assembly for electrolytic cell suitable for the hall-héroult process |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP3347509B1 (en) |
GB (1) | GB2542150A (en) |
WO (1) | WO2017042691A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2554702A (en) * | 2016-10-05 | 2018-04-11 | Dubai Aluminium Pjsc | Cathode assembly for electrolytic cell suitable for the Hall-Héroult process |
GB2595460A (en) * | 2020-05-26 | 2021-12-01 | Dubai Aluminium Pjsc | Cathode assembly with metallic collector bar systems for electrolytic cell suitable for the Hall-Héroult process |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0052577B1 (en) * | 1980-11-19 | 1984-02-15 | Schweizerische Aluminium AG | Anchorage for a cathode bar |
CH657383A5 (en) * | 1981-08-31 | 1986-08-29 | Alusuisse | ELECTROLYSIS PAN FOR PRODUCING ALUMINUM BY MELTFLOW ELECTROLYSIS AND METHOD FOR INSERTING THE IRON BAR. |
FR2606428B1 (en) * | 1986-11-10 | 1989-02-03 | Pechiney Aluminium | METHOD AND DEVICE FOR SEALING, UNDER PRESSURE, CATHODE RATES |
US6231745B1 (en) * | 1999-10-13 | 2001-05-15 | Alcoa Inc. | Cathode collector bar |
AUPQ584800A0 (en) * | 2000-02-25 | 2000-03-16 | Comalco Aluminium Limited | An electrical reduction cell |
WO2004031452A1 (en) * | 2002-10-02 | 2004-04-15 | Alcan International Limited | Collector bar providing discontinuous electrical connection to cathode block |
FR2868435B1 (en) * | 2004-04-02 | 2006-05-26 | Aluminium Pechiney Soc Par Act | CATHODIC ELEMENT FOR THE EQUIPMENT OF AN ELECTROLYSIS CELL INTENDED FOR THE PRODUCTION OF ALUMINUM |
US9371593B2 (en) * | 2012-09-11 | 2016-06-21 | Alcoa Inc. | Current collector bar apparatus, system, and method of using the same |
-
2015
- 2015-09-09 GB GB1515963.5A patent/GB2542150A/en not_active Withdrawn
-
2016
- 2016-09-07 EP EP16843770.5A patent/EP3347509B1/en active Active
- 2016-09-07 WO PCT/IB2016/055324 patent/WO2017042691A1/en active Application Filing
Non-Patent Citations (1)
Title |
---|
None * |
Also Published As
Publication number | Publication date |
---|---|
GB201515963D0 (en) | 2015-10-21 |
GB2542150A (en) | 2017-03-15 |
WO2017042691A1 (en) | 2017-03-16 |
EP3347509A1 (en) | 2018-07-18 |
EP3347509A4 (en) | 2019-05-01 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP1927679B1 (en) | Electrolysis cell for the production of aluminium comprising means to reduce the voltage drop | |
EP3277864B1 (en) | Cathode block for electrolytic cell suitable for the hall-héroult process | |
US11136682B2 (en) | Cathode current collector for a Hall-Heroult cell | |
CA2347858C (en) | Cathode collector bar with spacer for improved heat balance | |
EP3347509B1 (en) | Cathode assembly for electrolytic cell suitable for the hall-héroult process | |
EP3571333B1 (en) | Cathode assembly with metallic collector bar for electrolytic cell suitable for the hall-héroult process | |
EP3523463B1 (en) | Cathode assembly for electrolytic cell suitable for the hall-héroult process | |
EP4394089A1 (en) | Cathode collector bar and cathode assembly for hall-heroult process with low voltage drop and low thermal loss | |
WO2017168310A1 (en) | Cathode block with copper-aluminium insert for electrolytic cell suitable for the hall-héroult process | |
WO2016088001A1 (en) | Electrolytic pot for hall-heroult process, having a cathode formed of high and low cathode blocks | |
EP4158084A1 (en) | Cathode assembly with metallic collector bar systems for electrolytic cell suitable for the hall-héroult process |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE |
|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE |
|
17P | Request for examination filed |
Effective date: 20180409 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
AX | Request for extension of the european patent |
Extension state: BA ME |
|
DAV | Request for validation of the european patent (deleted) | ||
DAX | Request for extension of the european patent (deleted) | ||
A4 | Supplementary search report drawn up and despatched |
Effective date: 20190328 |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: C25C 3/10 20060101ALI20190322BHEP Ipc: C25C 3/16 20060101ALI20190322BHEP Ipc: C25C 3/06 20060101AFI20190322BHEP |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: GRANT OF PATENT IS INTENDED |
|
INTG | Intention to grant announced |
Effective date: 20200324 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE PATENT HAS BEEN GRANTED |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: REF Ref document number: 1298825 Country of ref document: AT Kind code of ref document: T Effective date: 20200815 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602016041580 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: IE Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: LT Ref legal event code: MG4D |
|
REG | Reference to a national code |
Ref country code: NO Ref legal event code: T2 Effective date: 20200805 |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: MP Effective date: 20200805 |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: MK05 Ref document number: 1298825 Country of ref document: AT Kind code of ref document: T Effective date: 20200805 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: BG Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20201105 Ref country code: SE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: HR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: PT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20201207 Ref country code: LT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: ES Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20201106 Ref country code: FI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: LV Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: RS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: PL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: CZ Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: RO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: SM Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: EE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R097 Ref document number: 602016041580 Country of ref document: DE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: MC Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
REG | Reference to a national code |
Ref country code: BE Ref legal event code: MM Effective date: 20200930 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200907 |
|
26N | No opposition filed |
Effective date: 20210507 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20201105 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200930 Ref country code: BE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200930 Ref country code: SI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: IE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200907 Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200930 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20201105 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: TR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: MT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 Ref country code: CY Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200805 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: IS Payment date: 20230928 Year of fee payment: 8 Ref country code: FR Payment date: 20230914 Year of fee payment: 8 Ref country code: DE Payment date: 20230928 Year of fee payment: 8 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NO Payment date: 20230929 Year of fee payment: 8 |