WO2002088432A1 - Arrangement of anode for utilisation in an electrolysis cell - Google Patents
Arrangement of anode for utilisation in an electrolysis cell Download PDFInfo
- Publication number
- WO2002088432A1 WO2002088432A1 PCT/NO2002/000157 NO0200157W WO02088432A1 WO 2002088432 A1 WO2002088432 A1 WO 2002088432A1 NO 0200157 W NO0200157 W NO 0200157W WO 02088432 A1 WO02088432 A1 WO 02088432A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- anode
- aluminium
- arrangement
- anodes
- electrolyte
- Prior art date
Links
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
- C25C3/12—Anodes
Definitions
- the present invention relates to an arrangement of anode for utilisation in an electrolysis cell. More specific it relates to improvements of anodes useful for retrofit of existing electrolysis cells, in which the anodes remains inert during operation.
- Aluminium is presently produced by electrolysis of an aluminium containing compound dissolved in a molten electrolyte, and the electrowinning process is performed in cells of conventional Hall-Heroult design. These electrolysis cells are equipped with horizontally aligned electrodes, where the electrically conductive anodes and cathodes of today's cells are made from carbon materials.
- the electrolyte is based on a mixture of sodium fluoride and aluminium fluoride, with smaller additions of alkaline and alkaline earth fluorides.
- the electrowinning process takes place as the current passed through the electrolyte from the anode to the cathode causes the electrical discharge of aluminium containing ions at the cathode, producing molten aluminium, and the formation of carbon dioxide at the anode.
- the present invention relates to an improved anode design mainly for retrofit of Hall- Heroult cells, where the anode of a principally inert material is fabricated in a specific manner to overcome one of the most important obstacles of utilisation of inert anodes in retrofit of Hall-Heroult cells;
- the purity of the produced aluminium metal can be achieved by increasing the electroactive surface of the anode, i.e. increasing the cathodic current density with respect to the anodic current density in the electrolysis cell. This feature can be obtained by optimising the shape of the anode surface and the overall anode structure.
- Inert anodes utilised in existing Hall-Heroult cells have to satisfy several demands.
- the most important demand is to contribute to the production of commercial purity aluminium metal, as pointed out by Thonstad and Olsen (Thonstad, J. and Olsen, E.: “Cell operation and metal purity challenges for the use of inert anodes", JOM, pp. 36-38, May 2001), without the need for new, costly purification processes.
- This requirement put demands on the electrochemical integrity of the inert anode material under the prevailing circumstances in the electrolyte.
- the design and/or electrode design can be utilised to contribute to maintain acceptable metal purities in retrofitted Hall-Heroult cells.
- the electrolyte (bath) in the aluminium electrolysis cell can for all practical purposes be considered to be saturated with inert anode components as dissolved oxides.
- the accumulation of anode material elements in the aluminium produced is then governed by the mass transfer coefficient for the species from the bath to the aluminium metal pool.
- a major drawback of inert anode retrofit of Hall-Heroult cells is that there are limited possibilities for reducing the large area of the metal pool cathode exposed to the electrolyte, without costly rebuilds of the cell (i.e. drained cell concepts).
- optional ways of reducing the metal contamination should be sought after, and one seductive possibility is to increase the electroactive surface of the anode.
- alumina containing species diffuse towards the anode and are discharged.
- the alumina concentration is different from the bulk electrolyte due to this discharge.
- the solubility of anode species (as oxides) will increase in the layer compared to the bulk electrolyte. It is well known that the solubility of inert anode material components, as oxides, decrease as the alumina concentration in the electrolyte increase.
- NO 176189 involves a novel cell design for an aluminium electrolysis cell involving the use of a horizontal, wetted cathode and several vertically aligned inert anodes.
- the purpose of the novel cell design is to increase the total anode surface area by inserting several vertical, planar anodes above the cathode, but maintained within the outlined outer circumference of the cathode, so that a low anodic current density can be maintained.
- the low anodic current density is necessary to operate the low temperature cell to prevent formation of fluorine containing species due to the low solubility of alumina in the suggested electrolyte.
- Such an electrolyte is not feasible to use in existing Hall-Heroult cells with retrofitted inert anodes.
- US 4,707,239 describes an electrode assembly for production of lead from a chloride based electrolyte.
- the anodes and cathodes
- the anodes are designed with saw tooth pattern and spacers to maintain stable ACD and the anodes are also equipped with holes for gas release.
- the purpose of the patented increased electrode area is to decrease voltage and energy requirements, increase metal production, increase effective inter electrode electrolyte area, enhance rapid gas removal, and reduce the overall metal production costs.
- the proposed anode design will have limited benefits in a retrofitted Hall- Heroult cell with inert anodes and a horizontal metal pool introducing variations in the effective ACD, without substantial changes made to the anode (electrical) properties).
- NO 308141 relates to the insertion of shapes (contours) on the cathode surface to "in situ" produce a rounding of the anode surface.
- the patent is based on the shapes (contours) being placed on the cathode of an Hall-Heroult cell, in which the cathodes are at least partially operated under drained conditions. This means that no horizontal metal pool is present as a continous surface across the whole cathode panel area.
- the "in situ" formation of the rounded anodes for enhanced gas release and reduced cell voltage is based on the use of carbon consumable anodes, and is as such not applicable to retrofit of existing Hall-Heroult cells with inert anodes, maintaining a horizontal metal pool in the cell.
- US 5,286,359 concerns the use of pyramid shaped anodes and cathodes in existing Hall- Heroult cells. Both electrode types are made from inert materials and the cell is operated at low ACDs with a metal pool located below the active cathode surfaces.
- the invention obtains increased anode and cathode surface area, although the proposed anode design would most likely operate at increased anodic current densities if deployed in a retrofitted cell with a horizontal metal pool due to the relative high electrical conductivity of the electrolyte.
- the present invention relates to an arrangement of anode for utilisation in an electrolysis cell. More specific it relates to improvements of anodes useful for retrofit of existing Hall- Heroult electrolysis cells, in which the anodes remains inert during operation.
- the proposed anode design takes into consideration the increase of the anode electroactive surface area in order to obtain one or more of the features listed below, whereof the two main features is:
- Anodic current density can be kept lower than in existing cells, or be maintained at the same level through an amperage increase.
- Figure 1 shows a first design of an anode surface with increased surface area
- Figure 2 shows a second proposed design of an anode surface with increased surface area
- Figure 3 shows a third possible design of an anode surface with increased surface area
- Figure 4 shows a fourth possible design of an anode surface with increased surface area
- Table 1 presents a comparison of different anode surface areas with a mainly horizontal underside with an extent of 700x1000 mm 2 with respect to alternative anode surface design modifications.
- an anode surface design (1) in which the surface area is increased through the introduction (forming, shaping) of a series of pyramidal elements
- FIG 2 is shown another anode surface design (10), in which the surface area is increased through the introduction (forming, shaping) of a series of (upward) protruding elements (11) with a pyramidal shape and rounded tops.
- a separate element (12) is also shown in perspective in the figure.
- figure 3 is shown a third possible design of an anode surface (20), in which the surface area is increased through the introduction (forming, shaping) of a series of (upward) protruding elements (21).
- a separate element (22) is also shown in perspective in the figure.
- this particular element is designed with a plurality of recesses/ steps (23, 24, 25, 26) that will actively contribute to the increase of the anode surface area.
- FIG 4 there is illustrated a fourth possible design of an anode surface (30), in which the surface area is increased through the introduction (forming, shaping) of a series of (upward) protruding elements (31).
- the figure shows the anode surface increasing measures applied in the length wise direction, although it may be applied both length wise and crosswise.
- a separate element (32) is also shown in perspective in the figure.
- this particular element is designed with first a series of waves defined by a sinus function (33). Thereafter, a second series of sinus waves (34) are superimposed on the first, creating what is called a double sinus function.
- This design will actively contribute to the increase of the anode surface area.
- Table 1 presents the effect on the anode surface area increase as a function of anode surface design changes. From the calculations in Table 1 it is clear that if the anode surface for instance is formed to a sinus-like shape, the anode surface area is considerably increased. By imposing the sinus function in two dimensions, the overall anode surface area does not increase if the amplitude and frequency is the same in both directions. However, by superimposing a second sinus function on the first one, where the superimposed sinus function has shorter wave length and a shorter amplitude, the surface area will increase even more. A sketch of this "double sinus" function is provided in figure 4. As indicated in Table 1, the double sinus function can increase the surface area of the anode by 240%. This corresponds to a (theoretical) current increase from 200 kA to 480 kA and yet maintaining the anodic current density of the retrofitted cell.
- the anode may be designed so that its electrical conductivity in the outer layer(s) is of the same order of magnitude as in the electrolyte. This can for instance be done by its construction based upon the conductivity of the material composition in the outer layer(s).
- Table 1 Effect of surface design modifications on anode surface area. Reference is a horizontal anode with a flat underside (700x1000 mm 2 ), and the table express the percent increase in anode surface area by introducing groves, saw tooth, rows of peaks and valleys, etc. on the electroactive anode surface,
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)
Abstract
Description
Claims
Priority Applications (10)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SK1328-2003A SK13282003A3 (en) | 2001-04-27 | 2002-04-24 | Arrangement of anode for utilisation in an electrolysis cell |
JP2002585705A JP2004527657A (en) | 2001-04-27 | 2002-04-24 | Anode arrangement for use in electrolysis cells |
BR0209208-5A BR0209208A (en) | 2001-04-27 | 2002-04-24 | Anode Array for Use in an Electrolysis Cell |
US10/476,151 US20040178079A1 (en) | 2001-04-27 | 2002-04-24 | Arrangement of anode for utilisation in an electrolysis cell |
EA200301182A EA200301182A1 (en) | 2001-04-27 | 2002-04-24 | DEVICE ANODA ELECTROLYTIC CELL |
EP02720682A EP1386023A1 (en) | 2001-04-27 | 2002-04-24 | Arrangement of anode for utilisation in an electrolysis cell |
NZ529979A NZ529979A (en) | 2001-04-27 | 2002-04-24 | Arrangement of anode for utilisation in an electrolysis cell provided that its working surface area is larger than its projected area |
CA002445676A CA2445676A1 (en) | 2001-04-27 | 2002-04-24 | Arrangement of anode for utilisation in an electrolysis cell |
NO20034729A NO20034729L (en) | 2001-04-27 | 2003-10-22 | Device at anode for use in an electrolytic cell |
IS7000A IS7000A (en) | 2001-04-27 | 2003-10-24 | Anode arrangement for use in electrolytic tanks |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NO20012118 | 2001-04-27 | ||
NO20012118A NO20012118D0 (en) | 2001-04-27 | 2001-04-27 | Device at anode for use in an electrolytic cell |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2002088432A1 true WO2002088432A1 (en) | 2002-11-07 |
Family
ID=19912411
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/NO2002/000157 WO2002088432A1 (en) | 2001-04-27 | 2002-04-24 | Arrangement of anode for utilisation in an electrolysis cell |
Country Status (15)
Country | Link |
---|---|
US (1) | US20040178079A1 (en) |
EP (1) | EP1386023A1 (en) |
JP (1) | JP2004527657A (en) |
CN (1) | CN1509347A (en) |
AR (1) | AR034317A1 (en) |
BR (1) | BR0209208A (en) |
CA (1) | CA2445676A1 (en) |
CZ (1) | CZ20033137A3 (en) |
EA (1) | EA200301182A1 (en) |
IS (1) | IS7000A (en) |
NO (1) | NO20012118D0 (en) |
NZ (1) | NZ529979A (en) |
SK (1) | SK13282003A3 (en) |
WO (1) | WO2002088432A1 (en) |
ZA (1) | ZA200308243B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2021515102A (en) * | 2018-02-28 | 2021-06-17 | マニュファクチュアリング システムズ リミテッド | Catalytic equipment and methods |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NO20024048D0 (en) * | 2002-08-23 | 2002-08-23 | Norsk Hydro As | Method of operation of an electrolytic cell and means for the same |
CN100392154C (en) * | 2005-03-10 | 2008-06-04 | 中南大学 | Protection means used for calcination starting or preheating exchanging inert anode for electrolysis of aluminium |
DE102010039638B4 (en) * | 2010-08-23 | 2015-11-19 | Sgl Carbon Se | Cathode, apparatus for aluminum extraction and use of the cathode in aluminum production |
CN106435652A (en) * | 2016-11-11 | 2017-02-22 | 中南大学 | Rolled porous lead alloy anode and preparation process thereof |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4681671A (en) * | 1985-02-18 | 1987-07-21 | Eltech Systems Corporation | Low temperature alumina electrolysis |
US4707239A (en) * | 1986-03-11 | 1987-11-17 | The United States Of America As Represented By The Secretary Of The Interior | Electrode assembly for molten metal production from molten electrolytes |
US5286359A (en) * | 1991-05-20 | 1994-02-15 | Reynolds Metals Company | Alumina reduction cell |
US6139704A (en) * | 1992-04-01 | 2000-10-31 | Moltech Invent S.A. | Application of refractory borides to protect carbon-containing components of aluminum production cells |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0560814B1 (en) * | 1990-11-28 | 1995-07-05 | MOLTECH Invent S.A. | Electrode assemblies and multimonopolar cells for aluminium electrowinning |
-
2001
- 2001-04-27 NO NO20012118A patent/NO20012118D0/en unknown
-
2002
- 2002-04-24 JP JP2002585705A patent/JP2004527657A/en not_active Abandoned
- 2002-04-24 EA EA200301182A patent/EA200301182A1/en unknown
- 2002-04-24 US US10/476,151 patent/US20040178079A1/en not_active Abandoned
- 2002-04-24 CA CA002445676A patent/CA2445676A1/en not_active Abandoned
- 2002-04-24 WO PCT/NO2002/000157 patent/WO2002088432A1/en active IP Right Grant
- 2002-04-24 CN CNA028099109A patent/CN1509347A/en active Pending
- 2002-04-24 BR BR0209208-5A patent/BR0209208A/en not_active IP Right Cessation
- 2002-04-24 NZ NZ529979A patent/NZ529979A/en active Application Filing
- 2002-04-24 EP EP02720682A patent/EP1386023A1/en not_active Withdrawn
- 2002-04-24 SK SK1328-2003A patent/SK13282003A3/en unknown
- 2002-04-24 CZ CZ20033137A patent/CZ20033137A3/en unknown
- 2002-04-26 AR ARP020101547A patent/AR034317A1/en unknown
-
2003
- 2003-10-22 ZA ZA200308243A patent/ZA200308243B/en unknown
- 2003-10-24 IS IS7000A patent/IS7000A/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4681671A (en) * | 1985-02-18 | 1987-07-21 | Eltech Systems Corporation | Low temperature alumina electrolysis |
US4707239A (en) * | 1986-03-11 | 1987-11-17 | The United States Of America As Represented By The Secretary Of The Interior | Electrode assembly for molten metal production from molten electrolytes |
US5286359A (en) * | 1991-05-20 | 1994-02-15 | Reynolds Metals Company | Alumina reduction cell |
US6139704A (en) * | 1992-04-01 | 2000-10-31 | Moltech Invent S.A. | Application of refractory borides to protect carbon-containing components of aluminum production cells |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2021515102A (en) * | 2018-02-28 | 2021-06-17 | マニュファクチュアリング システムズ リミテッド | Catalytic equipment and methods |
Also Published As
Publication number | Publication date |
---|---|
ZA200308243B (en) | 2004-07-01 |
NO20012118D0 (en) | 2001-04-27 |
EP1386023A1 (en) | 2004-02-04 |
CN1509347A (en) | 2004-06-30 |
AR034317A1 (en) | 2004-02-18 |
IS7000A (en) | 2003-10-24 |
CZ20033137A3 (en) | 2004-07-14 |
CA2445676A1 (en) | 2002-11-07 |
JP2004527657A (en) | 2004-09-09 |
BR0209208A (en) | 2004-07-06 |
SK13282003A3 (en) | 2004-05-04 |
EA200301182A1 (en) | 2004-04-29 |
NZ529979A (en) | 2005-08-26 |
US20040178079A1 (en) | 2004-09-16 |
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