CA1190517A - Reduction pot for fused salt electrolytic production of aluminum and process for installing the iron cathode bars - Google Patents
Reduction pot for fused salt electrolytic production of aluminum and process for installing the iron cathode barsInfo
- Publication number
- CA1190517A CA1190517A CA000410425A CA410425A CA1190517A CA 1190517 A CA1190517 A CA 1190517A CA 000410425 A CA000410425 A CA 000410425A CA 410425 A CA410425 A CA 410425A CA 1190517 A CA1190517 A CA 1190517A
- Authority
- CA
- Canada
- Prior art keywords
- iron bars
- channels
- bars
- carbon blocks
- reduction
- 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.)
- Expired
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
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- 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
ABSTRACT
A reduction pot for the fused salt electrolytic production of aluminum has channels which open downwards when in the working position in the carbon blocks of an electrically conductive lining, preferably the cross-sections of the channels at 500-850°C correspond exactly to that of iron bars heated to the same temperature and received in the channels, part of the weight of the carbon blocks is borne approximately uniformly by the iron bars which project out of both ends of the carbon blocks during the reduction process, the iron bars are installed in the reduction pot by inserting them at ambient temperature through windows in a steel outer shell into the interior of the pot' in this way it is possible to obtain the desired low contact resistance between the carbon blocks and the iron bars thereby providing for a more direct flow of electric current, without reducing the service life of the pot.
A reduction pot for the fused salt electrolytic production of aluminum has channels which open downwards when in the working position in the carbon blocks of an electrically conductive lining, preferably the cross-sections of the channels at 500-850°C correspond exactly to that of iron bars heated to the same temperature and received in the channels, part of the weight of the carbon blocks is borne approximately uniformly by the iron bars which project out of both ends of the carbon blocks during the reduction process, the iron bars are installed in the reduction pot by inserting them at ambient temperature through windows in a steel outer shell into the interior of the pot' in this way it is possible to obtain the desired low contact resistance between the carbon blocks and the iron bars thereby providing for a more direct flow of electric current, without reducing the service life of the pot.
Description
~
eduction pot Eor fused salt electrolytic production of aluminum and process for installing the iron cathode bars .~
The present invention relates to a reduction pot for fused salt electrolytic production oE aluminum where the said pot compris~s a steel shell, a thermally insulating laver and an electrically conductive inner lining which is resist-ant to molten materials and comprises carbon blocks running in the transverse direction with solid iron bars embedded in them and projecting out of the ends, and relates too to a process for inst~lling the iron bars.
The electrolytic process for producing aluminum from alum-¦inum oxide involves dissolving the latter in a fluoride ¦melt which is comprised for the greater part of cryolite.
¦The cathodically precipitated aluminum collects on the carbon floor of the cell under the fluoride melt, the sur-face of the liquid aluminum itself acting as the cathode.
Dipping into the melt from above are anodes which in conven-tional processes are made of amorphous carbon. Oxygen is l formed as a result of the electrolytic decomposition of thé l~
aluminum oxide; this oxygen reacts with the carbon of the anodes to form CO2 and CO. The electrolytic process takes ;~
place in the temperature range ca. 940 970 C.
I I ~
The inner lining of the reduction pot is made of carbon /
I 1:
. ~
5~L~
~blocks which have embedded in them at least one iron bar which is either continuous or separated in the middle. In ordex to achieve the smallest possible voltage drop accross the cell, the contact resistance between the iron bar and ¦ the carbon block must be as small as possible.
¦ Various methods for joininy the carbon block and the iron ~ bar are known to the expert in the field e.g.
I
- ramming in with a conductive paste - casting in with cast iron - adhesive fixing.
In conventional ~eduction pots the carbon blocks and the - iron bars may be of various dimensions viz., length, breadth and height and shape.
Today the method of casting the bars into the carbon blocks to attain good electrical contact is widely practised. The iron bars,laid in-to the channel in the carbon block,are held in place by pouring cast iron in around the bars. Both thP iron bars and the carbon block are preheated tog0ther and then cooled to the temperature of the surroundings after the cast iron has been poured in. As the thermal expansion and cont action of the iron ~s four times greater then that of the carbon, a gap results between the carbon and the cast iron when they are cooled. When the carbon block containing the iron bars is installed in a reduction cell, this gap does not close until the temperature of the cell is raised for putting it into service; the closing of this gap improves the electrical and mechanical contact between the iron and the carbon. If the gap formed by contraction closes before reaching the operating temperature, the faster expanding iron bar can act upon the carbon of the cathode element in such a manner khat cracks are produced in the cathode element A disadvantage of cast iron is that it has a relatively low electrical conductivity. Furthermore, wi.th the normal cast-in iron bars the compressive force in the uppermost region of the bar in its working position is often insufficient to produce the desired low contact resistance hetween the carbon block and the iron. This means that the electric curr-ent does not then flow via the shortest route through the carbon floor of the cell, but makes a detour into the side-walls of the iron bar instead of flowing directly through 20 ¦ the uppermost aceO Both factors can result in a voltage drop of e.g. up to 0.1 volt which is detrimental in terms of the energy balance of the cell. Some years ago therefore attempts were made, see eOg. J. E]ectrochemical Technology Vol. 5, No. 3-4, (1967), pp~ 152 154, to achieve direct contact between the iron bars and the carbon blocks.
~ ,~ : ' , A hole which corresponds to the shape and size of the iron bar is made in the carbon block and the iron bar placed in the hole without ramming paste, cast iron or adhesive. However, as no aluminum reduction cell has been S built using this principle in the relatively long intervening period, this process has apparently not proved itself.
According to the above mentioned article the iron bar must lie flush against the carbon at the working tem-perature of the cell. In practice this is hardly possible to achieve. During the electrolysis process, if the smallest dimensional inaccuracy exists, either the electrical contact resistance is too great or cracks are produced in the ~raphite block, the latter leading to a much reduced service life of the pot.
The invention see~s to avoid the above mentioned disadvantages of casting-in the iron bars in the carbon blocks, without reducing the service life of the reduction pot, yet lowering the contact resistance between the carbon block and the iron bar.
In accordance with one aspect of the invention, there is provided a reduction pot for the fused salt electro-l~tic production of aluminum comprising an outer steel shell, a thermally in,sulating layer and an electrically conductive inner: lining resistant to a molten charge, said electrically conductive innér lining being comrpised of transversely lying carbon blocks containing solid iron bars which project out of both ends of said carbon blocks, wherein channels which open downwards when in the working position are provided in said carbon blocks for receiving said iron bars.
In accordance with another aspect of the invention, there is provided a process for installing solid iron bars in a reduction pot used for the fused salt electrolytic production of aluminum, said pot comprising an outer steel " ~ .
shell, a thermally insulating layer and an electrically conductive inner lining resistant to a molten charge, said electrically conductive inner lining being comprised of transversely lying carbon blocks containing solid iron bars which project out of both ends of said carbon blocks, said carbon blocks con-taining channels which open downwards when in the working position, wherein said solid iron bars, at the temperature of its surroundings, are inserted through windows in said outer steel shell into the interior of said pot.
In particular and preferred embodiments the reduction pot has the following features:
-channels - which open downwards when in -the working position-are provided running in the longitudinal direction in each carbon block over at least 20% of its length, starti g from both snd faces, and such that the cross sec-tion of the channels at 500~850 C corresponds exactly to that of the iron bar heated to the same temperature, - the iron bars set in the channels and extending over at least 20~ of the length of the carbon block, starting from the end faces/ project out of -the whole of the lower face of the carbon block during the reduction process, and - a part of the weight of the carbon blocks is borne, approx-imately uniformly~ by all of the iron bars.
Trials have shown that the bottom opening in the channel -with normal dimensions of carbon block and iron bar - can be stretched approximately 1 mm before the carbon cracks or chips. A certain degree of elasticity in the carbon blocks is very important if anchoring the iron bars in the carbon without the use of cast iron.
This can be illustrated for the preferred temperature of around 700 C: At this temperature the channel and the iron bar in it have exactly the same cross section i.eu the iron bar lies intimately against the carbon along its whole length but without exerting any pressure against it. At higher temperatures, above 700C, for example at 940-970 C
at which the reduction process takes place, the iron bar resses against the carbon. Thanks to the elasticity of the carbon block, however, no crack is formed as would in ¦the case of a hole ra-ther than a channel.
¦A part of the weight of the carbon lining is distributed ¦approximately uniformly on the iron bars projecting out ¦of the carbon blocks. When the iron bars are in the working ¦ position therefore, they press against the correspondingly ¦ shaped part of the channel, even if the cross section of the ¦ iron bar is smaller than that of the channel. This pressure lO ¦ results in the smallest possible contact resistance between carbon and iron in that area closest to the liquid aluminum forming the cathode of the cell. The voltage drop is there-fore minimised with respect to two factors:
l - contact resistance between carbon and iron 15 ¦ - voltage drop in the carbon lining of the pot.
I
The iron bars can, in the conventional manner, extend over the whole length of the carbon blocks or be separated by a short or longer distance in the middle. It is known that, during the fused salt electrolytic production of alumin~, most of the electric current flows in the outer part o the iron bars in the reduction pot. It suffices therefore if the iron bars extend from both end faces of the carbon blocks into at least 20~ of the length of the carbon blocks towards the centre of the cell. In the centre of ~ ;
_ -- -- -- -- -- -- -- -- --- -- -- --the carbon blocks the iron bars can therefore be separated by up to 60% of the length of the block. 'rhe channels can extend the whole length of the carbon block or only over ~ a length corresponding -to that requirecl by -the iron bar; in the latter case, however, there is preferably a gap of 0.5 - 1 cm provided between the end faces of the iron bar and the channel.
The iron bars projecting preferably about 0.5 - 1.5 cm out of the bottom fac~ of the carbon blocks and the correspond-ingly shaped channel can be of any suitable geometric form.Preferably, however, the iron bars and the corresponding channel have a rounded cross section at least in the upper-most part as viewed in the working position. This provides the great advantage that, on prizing the sidewalls of the channel in the carbon block apart, the notch effect is minimised i~e. in channels with a rounded off upper section crack Eormation starts at higher pressures from the iron bars than in channels with angular cross sections there.
Iron bars and the corresponding channels of circular cross ~0 section are particularly advantageous as - round bars have the smallest surface ar~a for a constant cross section - which means the same electrical conduct-ivity with smaller thermal losses, - the strength of the block is increased considerably be-cause of the absence of a notch effect, - because of the higher maximum contact pressure, the con~
tact resistance between the carbon and the iron can be reduced, - simple, round win~ows for the cathode bars can be made in the steel shell of the pot, and these can be easily sealed with pre-fabricated materials, and - it is particularly easy to manufacture the bars.
lO ¦ The essential feature of the process according to the in-vention for installing the iron bars in a reduction pot with ¦ channels which are open at the bottom in the working position ¦ is that the iron bars~at the temperature of the surroundings, l are pushed, throu~h the windows in the steel shell into 15 ¦ the interior of the pot.
I
¦ The windows are usefully of the same geometric shape as ¦ the cross section of the iron bars. These windows are pre-ferably only slightly, in particular 0.5 - 2 cm larger l than the linear dimension of the bar cross section i.e.
20 ¦ there is only little play to allow the bar to pass through l the windoT~. In this case the gaps are easy to seal off.
I , _ g _ - ~-~
If the iron bars are, at least in the lower part, rectang-ular or tapering upwards, then they can - in keeping with the corxesponding channel - be laid on the layer of insul-lation. The carbon block can then be lowered onto it.
However, with all bar cross sections - and for reasons of geometry usually a necessity with bars of round cross section - the carbon blocks are lowered until e.g. about 0.5 - 2.5 cm above the layer of insulation; the iron bars are then pushed into the channels, and finally the carbon block lowered completely. These then rest on the iron bars which project out of the channels.
Th invention explained in greater detail in the following / with the help of a drawing illustrating an exemplified ¦ embodiment. The figure shows a schematic cross section throug]
15 ¦ a carbon block with two iron bars in the operating position but before completely lowering the carbon block.
¦ The carbon block 10 which is rectangular in cross section contains parallel, round iron bars 12 lying in the longitud-l inal direction in correspondingly shaped channels 14 which 20 ¦ are partly open at the bottom. Each iron bar 12 ls surrounded ¦ by inner sidewalls 16 of the carbon block 10. When the iron bar~ 12 exert pressure on the carbon block 10 at the operating ~emperature, the sidewalls 16 are pri~ed apart slightly. The edges lB of the sidewalls 16 are preferably rounded or cut away.
When the carbon block 10 has been fully lowered, the lower extremity 20 of the iron bar 12 rests on the insulation -not shown here. This causes the uppermost surface of theiron bar 12 to be pressed against the correspondîng part of the channel 14; the contac-t resistance between the car~on and the iron is then reduced to a minimum. The direct electr-ic current can then flow via the most direct route from the top surface of the carbon block 10 in the direction of the arrows and into the iron bar 12 with a minimum of contact resistance to overcome.
The essential advantages of the invention can be summarised as follows:
- The iron bars no longer have to be cast, stuck or rammed in but simply pushed through a window into a correspond-ing, downwards open, channel in the carbon block. This permits savings in energy, material, time~ equipment and workshop facilities.
- The carbon block is no longer exposed to the risks associ-ated with casting-in i.e. during transport, pre-heating, casting-in and handling.
'''--'-'''1-'' - The voltage drop in the electrolytic process can be lower-ed in the cathode part of the cell by up to 0.1 volt.
eduction pot Eor fused salt electrolytic production of aluminum and process for installing the iron cathode bars .~
The present invention relates to a reduction pot for fused salt electrolytic production oE aluminum where the said pot compris~s a steel shell, a thermally insulating laver and an electrically conductive inner lining which is resist-ant to molten materials and comprises carbon blocks running in the transverse direction with solid iron bars embedded in them and projecting out of the ends, and relates too to a process for inst~lling the iron bars.
The electrolytic process for producing aluminum from alum-¦inum oxide involves dissolving the latter in a fluoride ¦melt which is comprised for the greater part of cryolite.
¦The cathodically precipitated aluminum collects on the carbon floor of the cell under the fluoride melt, the sur-face of the liquid aluminum itself acting as the cathode.
Dipping into the melt from above are anodes which in conven-tional processes are made of amorphous carbon. Oxygen is l formed as a result of the electrolytic decomposition of thé l~
aluminum oxide; this oxygen reacts with the carbon of the anodes to form CO2 and CO. The electrolytic process takes ;~
place in the temperature range ca. 940 970 C.
I I ~
The inner lining of the reduction pot is made of carbon /
I 1:
. ~
5~L~
~blocks which have embedded in them at least one iron bar which is either continuous or separated in the middle. In ordex to achieve the smallest possible voltage drop accross the cell, the contact resistance between the iron bar and ¦ the carbon block must be as small as possible.
¦ Various methods for joininy the carbon block and the iron ~ bar are known to the expert in the field e.g.
I
- ramming in with a conductive paste - casting in with cast iron - adhesive fixing.
In conventional ~eduction pots the carbon blocks and the - iron bars may be of various dimensions viz., length, breadth and height and shape.
Today the method of casting the bars into the carbon blocks to attain good electrical contact is widely practised. The iron bars,laid in-to the channel in the carbon block,are held in place by pouring cast iron in around the bars. Both thP iron bars and the carbon block are preheated tog0ther and then cooled to the temperature of the surroundings after the cast iron has been poured in. As the thermal expansion and cont action of the iron ~s four times greater then that of the carbon, a gap results between the carbon and the cast iron when they are cooled. When the carbon block containing the iron bars is installed in a reduction cell, this gap does not close until the temperature of the cell is raised for putting it into service; the closing of this gap improves the electrical and mechanical contact between the iron and the carbon. If the gap formed by contraction closes before reaching the operating temperature, the faster expanding iron bar can act upon the carbon of the cathode element in such a manner khat cracks are produced in the cathode element A disadvantage of cast iron is that it has a relatively low electrical conductivity. Furthermore, wi.th the normal cast-in iron bars the compressive force in the uppermost region of the bar in its working position is often insufficient to produce the desired low contact resistance hetween the carbon block and the iron. This means that the electric curr-ent does not then flow via the shortest route through the carbon floor of the cell, but makes a detour into the side-walls of the iron bar instead of flowing directly through 20 ¦ the uppermost aceO Both factors can result in a voltage drop of e.g. up to 0.1 volt which is detrimental in terms of the energy balance of the cell. Some years ago therefore attempts were made, see eOg. J. E]ectrochemical Technology Vol. 5, No. 3-4, (1967), pp~ 152 154, to achieve direct contact between the iron bars and the carbon blocks.
~ ,~ : ' , A hole which corresponds to the shape and size of the iron bar is made in the carbon block and the iron bar placed in the hole without ramming paste, cast iron or adhesive. However, as no aluminum reduction cell has been S built using this principle in the relatively long intervening period, this process has apparently not proved itself.
According to the above mentioned article the iron bar must lie flush against the carbon at the working tem-perature of the cell. In practice this is hardly possible to achieve. During the electrolysis process, if the smallest dimensional inaccuracy exists, either the electrical contact resistance is too great or cracks are produced in the ~raphite block, the latter leading to a much reduced service life of the pot.
The invention see~s to avoid the above mentioned disadvantages of casting-in the iron bars in the carbon blocks, without reducing the service life of the reduction pot, yet lowering the contact resistance between the carbon block and the iron bar.
In accordance with one aspect of the invention, there is provided a reduction pot for the fused salt electro-l~tic production of aluminum comprising an outer steel shell, a thermally in,sulating layer and an electrically conductive inner: lining resistant to a molten charge, said electrically conductive innér lining being comrpised of transversely lying carbon blocks containing solid iron bars which project out of both ends of said carbon blocks, wherein channels which open downwards when in the working position are provided in said carbon blocks for receiving said iron bars.
In accordance with another aspect of the invention, there is provided a process for installing solid iron bars in a reduction pot used for the fused salt electrolytic production of aluminum, said pot comprising an outer steel " ~ .
shell, a thermally insulating layer and an electrically conductive inner lining resistant to a molten charge, said electrically conductive inner lining being comprised of transversely lying carbon blocks containing solid iron bars which project out of both ends of said carbon blocks, said carbon blocks con-taining channels which open downwards when in the working position, wherein said solid iron bars, at the temperature of its surroundings, are inserted through windows in said outer steel shell into the interior of said pot.
In particular and preferred embodiments the reduction pot has the following features:
-channels - which open downwards when in -the working position-are provided running in the longitudinal direction in each carbon block over at least 20% of its length, starti g from both snd faces, and such that the cross sec-tion of the channels at 500~850 C corresponds exactly to that of the iron bar heated to the same temperature, - the iron bars set in the channels and extending over at least 20~ of the length of the carbon block, starting from the end faces/ project out of -the whole of the lower face of the carbon block during the reduction process, and - a part of the weight of the carbon blocks is borne, approx-imately uniformly~ by all of the iron bars.
Trials have shown that the bottom opening in the channel -with normal dimensions of carbon block and iron bar - can be stretched approximately 1 mm before the carbon cracks or chips. A certain degree of elasticity in the carbon blocks is very important if anchoring the iron bars in the carbon without the use of cast iron.
This can be illustrated for the preferred temperature of around 700 C: At this temperature the channel and the iron bar in it have exactly the same cross section i.eu the iron bar lies intimately against the carbon along its whole length but without exerting any pressure against it. At higher temperatures, above 700C, for example at 940-970 C
at which the reduction process takes place, the iron bar resses against the carbon. Thanks to the elasticity of the carbon block, however, no crack is formed as would in ¦the case of a hole ra-ther than a channel.
¦A part of the weight of the carbon lining is distributed ¦approximately uniformly on the iron bars projecting out ¦of the carbon blocks. When the iron bars are in the working ¦ position therefore, they press against the correspondingly ¦ shaped part of the channel, even if the cross section of the ¦ iron bar is smaller than that of the channel. This pressure lO ¦ results in the smallest possible contact resistance between carbon and iron in that area closest to the liquid aluminum forming the cathode of the cell. The voltage drop is there-fore minimised with respect to two factors:
l - contact resistance between carbon and iron 15 ¦ - voltage drop in the carbon lining of the pot.
I
The iron bars can, in the conventional manner, extend over the whole length of the carbon blocks or be separated by a short or longer distance in the middle. It is known that, during the fused salt electrolytic production of alumin~, most of the electric current flows in the outer part o the iron bars in the reduction pot. It suffices therefore if the iron bars extend from both end faces of the carbon blocks into at least 20~ of the length of the carbon blocks towards the centre of the cell. In the centre of ~ ;
_ -- -- -- -- -- -- -- -- --- -- -- --the carbon blocks the iron bars can therefore be separated by up to 60% of the length of the block. 'rhe channels can extend the whole length of the carbon block or only over ~ a length corresponding -to that requirecl by -the iron bar; in the latter case, however, there is preferably a gap of 0.5 - 1 cm provided between the end faces of the iron bar and the channel.
The iron bars projecting preferably about 0.5 - 1.5 cm out of the bottom fac~ of the carbon blocks and the correspond-ingly shaped channel can be of any suitable geometric form.Preferably, however, the iron bars and the corresponding channel have a rounded cross section at least in the upper-most part as viewed in the working position. This provides the great advantage that, on prizing the sidewalls of the channel in the carbon block apart, the notch effect is minimised i~e. in channels with a rounded off upper section crack Eormation starts at higher pressures from the iron bars than in channels with angular cross sections there.
Iron bars and the corresponding channels of circular cross ~0 section are particularly advantageous as - round bars have the smallest surface ar~a for a constant cross section - which means the same electrical conduct-ivity with smaller thermal losses, - the strength of the block is increased considerably be-cause of the absence of a notch effect, - because of the higher maximum contact pressure, the con~
tact resistance between the carbon and the iron can be reduced, - simple, round win~ows for the cathode bars can be made in the steel shell of the pot, and these can be easily sealed with pre-fabricated materials, and - it is particularly easy to manufacture the bars.
lO ¦ The essential feature of the process according to the in-vention for installing the iron bars in a reduction pot with ¦ channels which are open at the bottom in the working position ¦ is that the iron bars~at the temperature of the surroundings, l are pushed, throu~h the windows in the steel shell into 15 ¦ the interior of the pot.
I
¦ The windows are usefully of the same geometric shape as ¦ the cross section of the iron bars. These windows are pre-ferably only slightly, in particular 0.5 - 2 cm larger l than the linear dimension of the bar cross section i.e.
20 ¦ there is only little play to allow the bar to pass through l the windoT~. In this case the gaps are easy to seal off.
I , _ g _ - ~-~
If the iron bars are, at least in the lower part, rectang-ular or tapering upwards, then they can - in keeping with the corxesponding channel - be laid on the layer of insul-lation. The carbon block can then be lowered onto it.
However, with all bar cross sections - and for reasons of geometry usually a necessity with bars of round cross section - the carbon blocks are lowered until e.g. about 0.5 - 2.5 cm above the layer of insulation; the iron bars are then pushed into the channels, and finally the carbon block lowered completely. These then rest on the iron bars which project out of the channels.
Th invention explained in greater detail in the following / with the help of a drawing illustrating an exemplified ¦ embodiment. The figure shows a schematic cross section throug]
15 ¦ a carbon block with two iron bars in the operating position but before completely lowering the carbon block.
¦ The carbon block 10 which is rectangular in cross section contains parallel, round iron bars 12 lying in the longitud-l inal direction in correspondingly shaped channels 14 which 20 ¦ are partly open at the bottom. Each iron bar 12 ls surrounded ¦ by inner sidewalls 16 of the carbon block 10. When the iron bar~ 12 exert pressure on the carbon block 10 at the operating ~emperature, the sidewalls 16 are pri~ed apart slightly. The edges lB of the sidewalls 16 are preferably rounded or cut away.
When the carbon block 10 has been fully lowered, the lower extremity 20 of the iron bar 12 rests on the insulation -not shown here. This causes the uppermost surface of theiron bar 12 to be pressed against the correspondîng part of the channel 14; the contac-t resistance between the car~on and the iron is then reduced to a minimum. The direct electr-ic current can then flow via the most direct route from the top surface of the carbon block 10 in the direction of the arrows and into the iron bar 12 with a minimum of contact resistance to overcome.
The essential advantages of the invention can be summarised as follows:
- The iron bars no longer have to be cast, stuck or rammed in but simply pushed through a window into a correspond-ing, downwards open, channel in the carbon block. This permits savings in energy, material, time~ equipment and workshop facilities.
- The carbon block is no longer exposed to the risks associ-ated with casting-in i.e. during transport, pre-heating, casting-in and handling.
'''--'-'''1-'' - The voltage drop in the electrolytic process can be lower-ed in the cathode part of the cell by up to 0.1 volt.
Claims (16)
1. A reduction pot for the fused salt electrolytic production of aluminum comprising an outer steel shell, a thermally insulating layer and an electrically conductive inner lining resistant to a molten charge, said electrically conductive inner lining being comprised of transversely lying carbon blocks containing solid iron bars which project out of both ends of said carbon blocks, wherein channels which open downwards when in the working position are provided in said carbon blocks for receiving said iron bars.
2. A reduction pot according to claim 1, wherein said channels extend in the longitudinal direction.
3. A reduction pot according to claim 1, wherein said channels extend over at least 20% of the length of said carbon blocks, starting from both end faces.
4. A reduction pot according to claim 1, 2 or 3, wherein the cross section of said channels at 500 to 850°C.
corresponds exactly to the cross section of said iron bars heated to the same temperature.
corresponds exactly to the cross section of said iron bars heated to the same temperature.
5. A reduction pot according to claim 1, 2 or 3, wherein said iron bars project out of the whole of the lower face of said carbon blocks during the reduction process.
6. A reduction pot according to claim 1, 2 or 3, wherein a part of the weight of said carbon blocks is supported approximately uniformly, by all of said iron bars.
7. A reduction pot according to claim 1, 2 or 3, wherein at about 700°C. the cross section of said channels corresponds exactly to the cross section of said iron bar.
8. A reduction pot according to claim 1, 2 or 3, wherein said iron bars project from 0.5 to 1.5 cm out of the bottom face of said carbon blocks during the reduction process.
9. A reduction pot according to claim 1, 2 or 3, wherein said channels and said corresponding iron bars have a rounded cross section in at least the uppermost region as viewed in the working position.
10. A reduction pot according to claim 1, 2 or 3, wherein said channels and said iron bars have a circular cross section.
11. A reduction pot according to claim 1, 2 or 3, wherein said outer steel shell comprises windows for passage of said bars into said pot, said windows having the same geometrical shape as the cross sections of said iron bars.
12. A reduction pot according to claim 1, 2 or 3, wherein said outer steel shell has windows which are from 0.5 to 2.0 cm larger than the corresponding linear dimen-sions of the cross sections of said iron bars, said windows being of the same geometrical shape as the cross sections of said iron bars.
13. A reduction pot for the fused salt electrolytic production of aluminum comprising an outer steel shell, a thermally insulating layer and an electrically conductive inner lining layer resistant to a molten charge, said electrically conductive inner lining comprising transversely lying carbon blocks containing solid iron bars which project out of opposed ends of said blocks, said blocks having longitudinal channels defined therein to receive said bars, said channels having an opening in facing relationship with a floor of said outer shell, said channels extending over at least 20% of the length of said blocks measured from both opposed end faces of said blocks, said channels having cross sectional dimensions which, at a temperature of 500 to 850°C., correspond exactly with the cross sectional dimensions of the iron bars heated to the same temperature, said bars projecting out of the lower face of said inner lining define by said blocks, and a part of the weight of said blocks being supported approximately uniformly, by all of said iron bars.
14. A process for installing solid iron bars in a reduction pot used for the fused salt electrolytic produc-tion of aluminum, said pot comprising an outer steel shell, a thermally insulating layer and an electrically conductive inner lining resistant to a molten charge, said electrically conductive inner lining being comprised of transversely lying carbon blocks containing solid iron bars which project out of both ends of said carbon blocks, said carbon blocks containing channels which open downwards when in the working position, wherein said solid iron bars, at the temperature of its surroundings, are inserted through windows in said outer steel shell into the interior of said pot.
15. A process according to claim 14, wherein said carbon blocks are simply lowered onto appropriately shaped said solid iron bars.
16. A process according to claim 15, wherein said carbon blocks are lowered in two stages, first to about 0.5 to 2.5 cm above said insulating layer, appropriately shaped said solid iron bars, and secondly, lowered com-pletely to said insulating layer.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH5567/81 | 1981-08-31 | ||
| CH5567/81A CH657383A5 (en) | 1981-08-31 | 1981-08-31 | ELECTROLYSIS PAN FOR PRODUCING ALUMINUM BY MELTFLOW ELECTROLYSIS AND METHOD FOR INSERTING THE IRON BAR. |
| DE3135083A DE3135083C1 (en) | 1981-08-31 | 1981-09-04 | Electrolytic pot for producing aluminium by means of molten-salt electrolysis and method for employing the iron bars |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190517A true CA1190517A (en) | 1985-07-16 |
Family
ID=25697998
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000410425A Expired CA1190517A (en) | 1981-08-31 | 1982-08-30 | Reduction pot for fused salt electrolytic production of aluminum and process for installing the iron cathode bars |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0073735B1 (en) |
| JP (1) | JPS5845390A (en) |
| AU (1) | AU557296B2 (en) |
| CA (1) | CA1190517A (en) |
| CH (1) | CH657383A5 (en) |
| DE (1) | DE3135083C1 (en) |
| ZA (1) | ZA826026B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NO157462C (en) * | 1985-10-24 | 1988-03-23 | Hydro Aluminium As | LAMINATED CARBON CATHOD FOR CELLS-MELT-ELECTROLYTIC ALUMINUM PREPARATION. |
| GB2542150A (en) * | 2015-09-09 | 2017-03-15 | Dubai Aluminium Pjsc | Cathode assembly for electrolytic cell suitable for the Hall-Héroult process |
| DE102016210693A1 (en) * | 2016-06-15 | 2017-12-21 | Sgl Cfl Ce Gmbh | Cathode block having a novel groove geometry |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2105247C3 (en) * | 1971-02-04 | 1980-06-12 | Schweizerische Aluminium Ag, Zuerich (Schweiz) | Furnace for the fused aluminum electrolysis |
| US3851377A (en) * | 1973-03-27 | 1974-12-03 | D Dumas | Sealing of metal bars in carbonized blocks |
| US4001104A (en) * | 1974-01-03 | 1977-01-04 | Union Carbide Corporation | Cemented collector bar assemblies for aluminum cell carbon bottom block |
| US4076610A (en) * | 1975-07-10 | 1978-02-28 | Elettrocarbonium S.P.A. | Cathode in cells for producing aluminium by electrolysis of smelted salts thereof |
| FR2318244A1 (en) * | 1975-07-17 | 1977-02-11 | Savoie Electrodes Refactaires | PROCESS FOR JOINING METAL BARS WITH CARBON BLOCKS |
-
1981
- 1981-08-31 CH CH5567/81A patent/CH657383A5/en not_active IP Right Cessation
- 1981-09-04 DE DE3135083A patent/DE3135083C1/en not_active Expired
-
1982
- 1982-08-18 EP EP82810344A patent/EP0073735B1/en not_active Expired
- 1982-08-19 ZA ZA826026A patent/ZA826026B/en unknown
- 1982-08-20 AU AU87480/82A patent/AU557296B2/en not_active Ceased
- 1982-08-30 CA CA000410425A patent/CA1190517A/en not_active Expired
- 1982-08-31 JP JP57151652A patent/JPS5845390A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CH657383A5 (en) | 1986-08-29 |
| AU557296B2 (en) | 1986-12-18 |
| JPS5845390A (en) | 1983-03-16 |
| EP0073735B1 (en) | 1985-10-23 |
| EP0073735A2 (en) | 1983-03-09 |
| ZA826026B (en) | 1983-07-27 |
| DE3135083C1 (en) | 1983-03-10 |
| AU8748082A (en) | 1983-03-10 |
| EP0073735A3 (en) | 1983-04-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |