US20100200420A1 - Control of by-pass current in multi-polar light metal reduction cells - Google Patents

Control of by-pass current in multi-polar light metal reduction cells Download PDF

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US20100200420A1
US20100200420A1 US12/677,599 US67759908A US2010200420A1 US 20100200420 A1 US20100200420 A1 US 20100200420A1 US 67759908 A US67759908 A US 67759908A US 2010200420 A1 US2010200420 A1 US 2010200420A1
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cell
polar
electrode
polar electrode
anode
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Adam J. Gesing
David K. Creber
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    • 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
    • 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
    • C25C3/02—Electrolytic production, recovery or refining of metals by electrolysis of melts of alkali or alkaline earth metals
    • 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
    • C25C3/04—Electrolytic production, recovery or refining of metals by electrolysis of melts of magnesium
    • 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
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/04—Diaphragms; Spacing elements

Definitions

  • This invention relates to the control of by-pass current in multi-polar metal reduction cells, particularly those used for the production of light metal such as magnesium, aluminum, sodium, lithium, etc.
  • Multi-polar electrolysis cells may be used, where such cells have at least one, and usually several, multi-polar electrodes positioned in the space between an anode and a cathode forming a series connection of sub-cells.
  • the multi-polar electrodes increase the number of electrolysis steps at which electrolysis may take place, and thus increase the cell energy and production efficiency compared to mono-polar cells of the same amperage.
  • a gas is normally generated in the electrolyte during the process of electrolysis (for example, chlorine is generated when magnesium is derived from magnesium chloride). In a vertical electrode cell, the resulting gas bubbles rise between the electrodes, lifting the surrounding electrolyte with them.
  • Multi-polar electrolysis cells that employ the gas-lift principal may be of two main kinds.
  • the anode, cathode and multi-polar electrodes are planar and are arranged face-to-face in a row with suitable gaps therebetween.
  • the anode is in the form of a solid upright rod and the cathode and multi-polar electrodes are in the form of hollow cylinders of different diameters encircling the rod at increasing distances, the cathode being the most distant from the anode rod.
  • the electrodes are encased in a container lined with refractory material that provides thermal insulation for the molten electrolyte and the molten metal.
  • An arrangement for the collection and removal of generated gas is also provided at the upper end of the cell.
  • bypass current travels around the ends of the multi-polar electrodes following a more direct path through the electrolyte between the cathode and the anode rather than passing between the multi-polar electrodes through the series-connected sub-cells formed between adjacent electrodes. This leads to reduced cell productivity, increased power consumption and decreased current efficiency.
  • the by-pass current may typically reduce current efficiency by 3 to 5% or more.
  • a by-pass current forms most readily at the upper end of the electrodes if the electrolyte overflows the electrodes driven by the rising volume of gas.
  • the by-pass current has been kept in check by designing the electrode cassettes (i.e. electrode assemblies) in such a way that the thickness of the electrolyte layer passing over the tops of the electrodes is minimized. This requires careful electrolyte level control to ensure that adequate, but not excessive, flow is maintained. Despite such measures, by-pass currents still flow and there is a reduction of current efficiency. Examples of prior patents in which level control is suggested to reduce the by-pass current are U.S. Pat. No. 4,514,269 which issued on Apr. 30, 1985 to Sivilotti, and U.S. Pat. No.
  • Certain exemplary embodiments can provide a multi-polar electrolytic cell for producing a light metal by electrolysis of a corresponding metal salt.
  • the cell comprises a molten electrolyte containing a metal salt that produces a light metal and a gas when electrolyzed, and an arrangement of generally vertical electrodes surrounded by the molten electrolyte, including an anode, a cathode and at least one current-conducting multi-polar electrode interposed between the anode and the cathode.
  • At least one of the multi-polar electrode(s) has an upper end with an electrical insulator positioned over the upper end (at least partially covering the upper end surface of the electrode). In use of the cell, the insulator(s) is (are) immersed beneath the electrolyte as it overflows the electrodes.
  • the cell may minimize or eliminate by-pass current normally encountered in multi-polar electrolysis cells.
  • Cells of this kind preferably lack outlets or channels for the rising electrolyte that would permit the electrolyte to be diverted around and prevented from rising over the upper ends of the electrodes.
  • the electrode structure (whether planar or cylindrical) is preferably such that all or substantially all of the rising electrolyte passes over the insulated upper ends of the multi-polar electrode(s), as well as the cathode, during normal operation of the cell.
  • the cells are preferably of a kind that, but for the insulation of the upper ends of the electrodes as disclosed herein, would develop a significant by-pass current during use.
  • exemplary embodiments can provide a method of minimizing or eliminating by-pass current between an anode and a cathode in a multi-polar electrolysis cell suitable for production of a light metal, the method comprising electrically insulating an upper end of at least one multi-polar electrode of the cell, and conducting electrolysis with the insulated upper end maintained below an upper surface of molten electrolyte containing a metal salt to be electrolyzed held within the cell.
  • by-pass current we mean current that flows around (above, below and beside) a multi-polar electrode resulting in a skipping of at least one multi-polar electrolysis step between electrodes (anode, cathode or multi-polar electrode) without contributing to the electrolysis reaction. It is sometimes referred to as current leakage and it represents a loss of current efficiency of the cell.
  • the insulators are covered by electrolyte either by virtue of the overflow of the rising electrolyte and/or by virtue of the insulators being positioned below the upper level of the electrolyte that it adopts when current is not flowing through the cell.
  • the upper ends of the electrodes, or at least the insulators may stand proud of the upper level of the electrolyte when no current is flowing. In the latter case, they may be immersed.
  • Such insulation may be placed on the face of the anode (or surrounding a cylindrical anode). The insulation can be effective even if it is entirely below the electrolyte surface, but it is particularly preferred that it extend above the electrolyte surface. This insulation minimizes further the bypass currents that would flow from the anode across the adjacent multi-polar electrode even when the multi-polar electrode has an insulator present.
  • the anode and multi-polar electrodes used in the present invention may be made of graphite, metals, cermets, composites, and laminates of these materials.
  • the cathode is generally made of steel.
  • the electrodes are generally non-consumable in that the electrode is not consumed by the main electrolysis reaction. However, side reactions may contribute to some deterioration of the electrode material.
  • the electrical insulators should preferably be stable in the cell environment and resistant to attack or degradation by electrolyte and the products of electrolysis at the cell operating temperature for the duration of the cell life. When magnesium is the metal being produced, alumina is the preferred material for the insulators. Other materials may alternatively be employed, e.g.
  • the insulator may be a solid sintered or fused-cast ceramic block keyed into the edge of the graphite electrode or held in place by ceramic spacers.
  • the insulators may comprise a coating layer applied to the appropriately shaped electrode edge by a ceramic coating process, such as plasma spraying, sputter deposition and chemical vapour deposition.
  • Still another electrode edge insulator may comprise thin ceramic tiles adhesively bonded to the electrode by cement.
  • One way of providing the upper ends of the multi-polar electrodes with electrically insulating surfaces is to add pieces of insulating refractory material to the upper ends of the electrically conductive parts of the electrodes.
  • FIG. 1 is plan view of a multi-polar electrolysis cell with the top removed suitable for use with the present invention, the cell containing a cassette of electrodes of upright planar shape;
  • FIG. 2 is a plan view of a multi-polar electrolysis cell with the top removed suitable for use with the present invention, the cell containing a plurality of cassettes or electrodes of upright cylindrical shape;
  • FIG. 3 is a vertical cross-section of an electrode cassette along the line A-A in either FIG. 1 or FIG. 2 in which the multi-polar electrodes (either planar or cylindrical) are insulated in accordance with one preferred form of the present invention;
  • FIG. 4 is a vertical cross-section of an electrode cassette along the line A-A on either FIG. 1 or FIG. 2 in which the multi-polar electrodes (either planar or cylindrical) are insulated in accordance with a preferred form of the present invention, but with the upper ends at different heights;
  • FIG. 5 is a vertical cross-section of an electrolysis cell provided with one or more cylindrical cassettes of the kind shown in FIG. 4 ;
  • FIGS. 6A to 6G illustrate various ways in which insulating material may be fixed to the electrically-conductive material of electrodes
  • FIG. 7A is a partial perspective view of an alternative design of insulating block suitable for insulating upper ends of planar or electrodes;
  • FIG. 7B is a partial perspective view of an alternative design of insulating block suitable for insulating upper ends of cylindrical electrodes
  • FIG. 8 is a graph showing the variation of by-pass currents in one example of a cell with insulators of various heights on the tops of the multi-polar electrodes.
  • FIG. 9 is a graph of the measured current efficiency of a cell using insulators on the tops of some multi-polar electrodes relative to a cell without insulators over an extended period of cell operation.
  • the present invention is capable of being used with multi-polar cells of all kinds, but mainly multi-polar cells that have vertical (or sloping) electrodes that are planar or cylindrical.
  • the exemplary embodiments relate in particular to such cells in which electrolyte circulation is achieved by use of a “gas-lift” principal in which a gas generated during electrolysis over the entire active surfaces of the electrodes causes upward flow of electrolyte in the inter-electrode gaps.
  • the electrolyte reaches the tops of the gaps, it overflows the adjacent tops of the electrodes (the multi-polar electrodes and cathode) and returns to the body of the cell.
  • normally no channels are provided to divert the electrolyte and to avoid such overflow.
  • the indicated flow of electrolyte allows for efficiency of electrolyte circulation, but permits communication between electrodes and hence the possibility of the development of bypass current.
  • a good circulation in the cell is needed to keep the inter-electrode gaps supplied with fresh salt to be electrolyzed, permit efficient removal of the anode gas which is generated and collection of the metal cathode product and thus allow productivity to be maintained. It is therefore desired to reduce bypass current (current efficiency loss) without reducing the efficiency of circulation.
  • FIGS. 1 and 2 are simplified plan views of electrolysis cells 10 each with a top wall removed.
  • the cell of FIG. 1 has an electrode cassette made up of planar electrodes, whereas the cell of FIG. 2 has several electrode cassettes made up of cylindrical electrodes.
  • the cell 10 includes an outer wall 11 provided with a refractory lining 12 that provides insulation against heat loss and flow of electricity.
  • the cell is divided into an electrode compartment 13 and a reservoir compartment 14 separated from each other by a vertical refractory wall 15 .
  • the compartments 13 and 14 communicate with each other via channels (not shown in these figures, but shown later in relation to FIG. 5 ) provided near the top and bottom of the wall 15 . This allows molten electrolyte 16 to circulate freely between the two compartments.
  • Fresh metal salt may be added to the electrolyte in reservoir compartment 14 from time to time to replenish the salt consumed during the process of electrolysis.
  • the electrode compartment 13 of FIG. 1 contains an arrangement of electrodes in the form of an electrode cassette 18 made up of a vertical planar anode 19 flanked on each side at a distance by a pair of vertical planar cathodes 20 . Interposed between the anode and the cathodes are eight vertical planar multi-polar electrodes 21 , four on one side of the anode and four on the other side of the anode.
  • Ceramic insulators made up of a ceramic anode side insulator 25 , ceramic cathode side insulators 26 , ceramic side edge insulators 27 and ceramic spacers 28 . These ceramic insulators and spacers prevent the development of bypass current at the vertical side edges 22 and 23 of the electrode cassette 18 . They also prevent movement of electrolyte 16 into or out of the cassette 18 at the side edges 22 and 23 so the flow of electrolyte is kept vertical. In some embodiments, it is convenient if these insulators are made part of the adjacent outer wall 11 , 12 and the vertical refractory wall 15 . The electrode cassette 18 is positioned between short vertical refractory walls 24 .
  • the electrode compartment of FIG. 2 contains a plurality of cylindrical electrode assemblies or cassettes 18 made up of an outer cylindrical cathode 20 , an inner rod-like cylindrical anode 19 , and four multi-polar electrodes 21 in between the cathode and anode.
  • the electrodes are nested together in the manner shown.
  • FIG. 3 is a vertical cross-section through an electrode cassette 18 along line A-A in either FIG. 1 or in FIG. 2 as these cross-sections of both figures look essentially the same.
  • the cassette 18 of electrodes is made up of the anode 19 (which may be planar as in FIG. 1 or a circular rod as in FIG. 2 ) and the cathode 20 (again either planar or cylindrical).
  • the gap between the anode and the cathode on each side is filled by four different spaced multi-polar electrodes 21 (the embodiment of FIG. 1 ) or different parts of the four cylindrical multi-polar electrodes (the embodiment of FIG. 2 ) separated by gaps 36 .
  • the upper ends 29 of the multi-polar electrodes 21 are capped by insulators 33 which are blocks made of an electrically-insulating refractory material. The method of attachment of the blocks to the electrodes is discussed in detail later.
  • the anode 19 rests on a ceramic spacer block 40 that in turn rests on the floor of the cell or more preferably on a support within the cell (not shown in this view).
  • the cathode 20 rests on a refractory ceramic spacer 41 and the multi-polar electrodes 21 rest on aligned ceramic refractory 20 spacer blocks 42 which rest on a support within the cell (not shown).
  • the blocks 40 , 41 and 42 are provided with gaps 43 that align with the gaps 36 between the electrodes so that electrolyte may enter the cassette 18 of electrodes from below.
  • the anode 19 is also provided with a ceramic refractory circumferential insert 45 on its exterior surface in the region confronting the upper ends of the multi-polar electrodes and the insulators 33 .
  • This insert provides an insulating refractory shield that further minimizes the risk of bypass current.
  • the cassettes 18 as shown in FIG. 3 are immersed in the electrolyte 16 of the cell such that the tops of the insulators 33 are, at least in use, positioned below the surface of the electrolyte 16 .
  • the gas generated in the gaps 36 between the anode, cathode and multi-polar electrodes causes electrolyte (now containing droplets of metal resulting from the electrolysis) to flow upwards, and to form a layer 50 of electrolyte on the top of the electrodes which flows outwardly in a transverse manner to the openings or channels around the cassette.
  • the electrolyte then flows into the electrode compartment 13 ( FIG. 1 and FIG.
  • FIG. 4 shows an alternative embodiment having cylindrical electrode cassettes 18 in which the electrodes are configured as in FIG. 3 , except that the upper ends of the insulators 33 on the top of the multi-polar electrodes 21 are arranged in a stepwise manner of increasing height towards the anode 19 .
  • a cassette can be operated with the electrodes immersed well below the surface of the electrolyte, but can also be advantageously operated with the electrolyte level controlled so that the electrolyte containing the metal droplets cascades over the tops to achieve a relatively thin layer of electrolyte as shown at 50 .
  • This type of stepped arrangement is shown for cassettes without insulators on the top of the electrodes in U.S. Pat. No. 5,935,394 (the disclosure of which is incorporated herein by reference).
  • Such a stepped arrangement has been used to reduce the bypass currents with some effectiveness, but the addition of insulators adds a still further significant reduction of bypass currents in arrangements of this kind.
  • FIG. 5 shows a vertical cross-section of a cell 10 similar to that of FIG. 2 but provided with at least one electrode cassette 18 of the type shown in FIG. 4 .
  • the cell 10 comprises a vessel provided with outer walls 11 having a refractory and insulating lining 12 .
  • the vessel has a lined cover 17 that is sealed against gas leaks from the cell but has a gas vent 24 which may be connected to a conduit (not shown) for gas delivery to other equipment.
  • the electrode cassette 18 is connected to a current source (not shown) by an anode busbar 51 at the top of the anode 19 and by a cathode busbar 52 welded to the cathode 20 of the electrode cassette 18 , and passing through the wall 11 of the cell, where it is sealed against electrolyte leakage.
  • the cell is divided by vertical refractory wall 15 into an electrode compartment 13 occupied by the electrode cassette or cassettes 18 , and reservoir compartment 14 where metal collection takes place.
  • the vertical refractory wall 15 is provided with an upper opening 31 and lowery opening 32 (or more than one of such openings).
  • the bottom of each electrode cassette 18 is supported above the floor of the electrode compartment 13 by refractory supports 34 . These supports are sufficiently open that they do not impede the flow of electrolyte to and within the cassette.
  • the cell is filled with molten electrolyte 16 to a level 35 in the reservoir compartment 14 .
  • the electrolyte flows upwards between the electrodes in the electrode cassette 18 , flows over the tops of the insulators 33 to the electrode compartment 13 , and into the reservoir compartment via the opening 31 .
  • the molten metal is entrained as droplets in the electrolyte stream and the droplets float to the surface in the reservoir compartment, where they coalesce to form a floating layer 30 .
  • the electrolyte eventually flows back to the electrode compartment 13 via the lower opening 32 .
  • Metal is periodically removed by vacuum tapping via an opening (not shown) in the top cover 17 .
  • the cover 17 may also have a closable opening (not shown) for the introduction of metal salt into the cell from time to time.
  • Means are also preferably provided to maintain the upper level of the electrolyte 16 at a predetermined level 35 in the cell.
  • Such means are known in the prior art, for example in U.S. Pat. No. 4,518,475 (the disclosure of which is incorporated herein by reference).
  • the control of the electrolyte level is less critical.
  • the insulators 33 are preferably positively secured to the electrodes 21 to prevent their dislodgment during operation of the cell. Depending on the material used for the insulators, they may experience buoyancy when submerged in the electrolyte, so there is therefore usually a need to attach the insulators by means other than gravity alone.
  • the electrical insulation helps to prevent the development of bypass current between the anode and the cathode.
  • the insulators 33 effectively provide the multi-polar electrodes with electrical insulation extending completely along the top edges 29 of the electrodes.
  • FIGS. 6A through 6G illustrate some ways in which the insulators may be attached to the multi-polar electrodes, or to an anode or cathode. These methods employ pins or inserts 61 ( FIGS. 6A , 6 B, 6 C, 6 D), tongue and grooves 63 ( FIGS. 6A , 6 B and 6 C), dovetails 62 ( FIGS. 6E , 6 F, 6 G), adhesive or the like, or a combination of two or more of these mounting features.
  • the ceramic materials can be fixed securely to the conductive electrode material to prevent dislodgement of the ceramic during operation of the cell.
  • the fixtures can be asymmetric or “off-centre” as shown, or symmetric. If off-centre, the thicker electrode material is preferably positioned on the anode face of the electrode since that surface is more likely to experience wear and loss of material in use, and the off-centre positioning thus increases the effective operating life of the cassette.
  • FIG. 7A is a partial view of the top of an electrode cassette which illustrates another preferred embodiment of the invention in which the insulators 33 are interconnected to form a unitary block 33 A.
  • the multi-polar electrodes 21 are each capped at their upper ends 29 with an elongated insulator 33 that covers the entire upper end surface of the electrode.
  • the insulators 33 are joined together by spacers 34 and end plates 35 .
  • the gaps 36 ′ between the spacers and end plates align with the inter-electrode gaps 36 between the electrodes 21 .
  • the spacers 34 and end plates 35 extend across the inter-electrode gaps, they are narrow enough not to impede the flow of electrolyte unduly. However, they support the insulators 33 and make the cassette more rigid and secure.
  • FIG. 7B shows a similar arrangement for cylindrical electrode cassettes.
  • the insulators 33 may be joined to form a block 33 B of ceramic material having the shape as shown in FIG. 7B .
  • the block 33 B consists of insulators 33 that are circular (in plan view) with rounded upper ends 55 .
  • a circular gap 36 ′ aligns with the inter-electrode gap 36 between the electrodes 21 .
  • Spacers 34 interconnect the insulators in diametrically opposed positions, thus unifying the block 33 B. Again, the spacers 34 do not unduly restrict the flow of electrolyte.
  • the following generally comments can be made about the dimensions of the insulators 33 .
  • electrical resistance to the bypass current is determined by the ratio of the length of the gap between the adjacent insulators and the cross-sectional area of the gap which is proportional to its width. Optimization is preferred to achieve the best balance between the hydrodynamic resistance to electrolyte flow and the electrical resistance to bypass currents.
  • the preferred dimensions for the insulators can be stated as follows, in which the terms “width”, “length” and “height” have the following meanings for cells having both planar and cylindrical electrodes:
  • Width The through-thickness of the multi-polar electrode, parallel to the direction that the current is traveling though the multi-polar electrode.
  • Length The horizontal direction, parallel to the electrode face, generally normal to the current flow.
  • Height The vertical direction, parallel to the face of the electrode face.
  • ACD multi-polar electrodes
  • Width Between 0.1 and 1.5 times the width of the underlying multi-polar electrode, and more preferably more than 0.5 times the width. Length: Equal to the length of the multi-polar electrode (does not extend beyond the ends of the multi-polar electrodes). Height: 1 to 20 times the electrode gap (ACD).
  • insulators In cells having more than one multi-polar electrode, it is desirable to provide insulators on the upper ends of all the multi-polar electrodes. However, the provision of insulators on only one or some of the multi-polar electrodes is better than having no insulators at all.
  • Bypass currents over the tops of the multi-polar electrodes are affected by electrolyte overflow depth, number of multi-polar electrodes, thickness of multi-polar electrodes and gap between multi-polar electrodes, decomposition potential and electrolyte conductivity.
  • the effect of placing insulators at the electrode upper ends is to add an additional degree of resistance to the leakage current pathway. This extra electrical resistance, which is developed by increasing the bypass current pathway through the electrolyte, has the effect of decreasing the overall bypass current. developed by increasing the bypass current pathway through the electrolyte, has the effect of decreasing the overall bypass current.
  • FIG. 8 An example of the variation of bypass current for a range of insulator heights (expressed as multiples of the ACD) has been calculated and is shown in FIG. 8 .
  • Insulator heights as low as about 1 times the ACD are effective, and beyond heights that are 20 times the ACD, the improvement with increased height is less.
  • a height of more than 10 times the ACD is not preferred, and a height of at least 5 times the ACD ensures an economically useful effect on the bypass currents without a significant negative impact on the electrolyte flow or cell productivity.
  • an electrolytic reduction cell having 24 planar multi-polar electrodes was provided with elongated rectangular insulators attached to the tops of four of the multi-polar electrodes.
  • the refractory material used for the insulators was made from a 93% alumina/5% silica castable mixture.
  • the width of each insulator was the same as that of the multi-polar electrode on which it rested, the length was the same as that of the multi-polar electrode length and the height was 6 times the average ACD.
  • the cell was operated for 685 days under normal conditions. The test showed that the cell operated properly, and, although the multi-polar electrodes did erode over the operational lifetime of the cell, the insulator dimensions did not change and the insulators remained fixed to the top of the multi-polar electrodes.
  • the current efficiency was calculated, compared to a cell lacking such insulators and the results are plotted against cell life in FIG. 9 . This shows a consistently higher current efficiency with even a few insulators over the case with no such insulators.

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  • Chemical Kinetics & Catalysis (AREA)
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  • Metallurgy (AREA)
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  • Electrolytic Production Of Metals (AREA)
US12/677,599 2007-09-14 2008-09-03 Control of by-pass current in multi-polar light metal reduction cells Abandoned US20100200420A1 (en)

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US12/677,599 US20100200420A1 (en) 2007-09-14 2008-09-03 Control of by-pass current in multi-polar light metal reduction cells
PCT/CA2008/001544 WO2009033260A1 (fr) 2007-09-14 2008-09-03 Régulation de courant de dérivation dans des cellules d'électrolyse de métal léger multipolaires

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CN110808354A (zh) * 2019-11-25 2020-02-18 衡阳凯新特种材料科技有限公司 绝缘性能好的耐用型氮化硅电极保护罩

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CN102206839A (zh) * 2011-06-24 2011-10-05 遵宝钛业有限公司 一种镁电解槽的砌筑方法
CN104562092B (zh) * 2015-02-03 2017-05-10 奉新赣锋锂业有限公司 一种多阳极金属锂电解槽

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CA2697396C (fr) 2011-11-08
AU2008299528B2 (en) 2012-02-16
CA2697396A1 (fr) 2009-03-19
AU2008299528A1 (en) 2009-03-19
RU2010112494A (ru) 2011-10-20
CN101802270A (zh) 2010-08-11
WO2009033260A1 (fr) 2009-03-19
NO20100526L (no) 2010-06-11

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