CA1150189A - Chisel for a crust breaking facility and method for operation of the same - Google Patents
Chisel for a crust breaking facility and method for operation of the sameInfo
- Publication number
- CA1150189A CA1150189A CA000359982A CA359982A CA1150189A CA 1150189 A CA1150189 A CA 1150189A CA 000359982 A CA000359982 A CA 000359982A CA 359982 A CA359982 A CA 359982A CA 1150189 A CA1150189 A CA 1150189A
- Authority
- CA
- Canada
- Prior art keywords
- chisel
- projection
- crust
- sidewall
- cross
- 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
- C25C3/14—Devices for feeding or crust breaking
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D17/00—Details of, or accessories for, portable power-driven percussive tools
- B25D17/02—Percussive tool bits
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Electrolytic Production Of Metals (AREA)
- Preliminary Treatment Of Fibers (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
- Percussive Tools And Related Accessories (AREA)
- Organic Insulating Materials (AREA)
- Debarking, Splitting, And Disintegration Of Timber (AREA)
- Disintegrating Or Milling (AREA)
- Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Immobilizing And Processing Of Enzymes And Microorganisms (AREA)
- Sealing Battery Cases Or Jackets (AREA)
- Primary Cells (AREA)
- Hybrid Cells (AREA)
- Working Measures On Existing Buildindgs (AREA)
- Crushing And Pulverization Processes (AREA)
- Crushing And Grinding (AREA)
Abstract
A B S T R A C T
Device and method for breaking open the solidified crust of electrolyte on an electrolytic cell, in particular a cell for producing aluminum. At least one projection is provided on the lower part of the shaft of a chisel used on a crust breaker.
After breaking through the crust, the chisel is lowered further at least until the lowest projection or projections reaches/
reach the lower half of the crust.
Device and method for breaking open the solidified crust of electrolyte on an electrolytic cell, in particular a cell for producing aluminum. At least one projection is provided on the lower part of the shaft of a chisel used on a crust breaker.
After breaking through the crust, the chisel is lowered further at least until the lowest projection or projections reaches/
reach the lower half of the crust.
Description
Chisel for a crust breaking facility and method for operation of the same The invention relates to a chisel for a facili-ty for breaking open the solidified crust on an electrolytic cell, in particular S on a cell for producing aluminum, and a method ~or using the chisel in practice.
In the manu~acture of aluminum from aluminum oxide the latter is dissolved in a fluoride melt made up for the greater part of cryolite. The aluminwm which separates out at the cathode collects under the fluoride melt on the carbon Eloor of the cell; -the sur-face of this liquid aluminum acts as the cathode. Dipping into the melt from above are anodes which, in the conventional reduc-tion process~ are made of amorphous carbon. As a result of the electrolytic decomposition of the aluminum oxide, oxygen is pro-duced at the carbon anodes; this oxygen combines with the carbonin the anodes to form C02 and CO. The e~ = process takes place in a temperature range of approximately 940-970C.
The concentration of aluminum oxide decreases in the course of the process. At an A12O3 concentration of 1-2 wt.% the so-called anode effect occurs producing an increase in vol-tage from e.g.
4-4.5 V to 30 V and more. Then at the latest the crust mus-t be broken open and the concentration of aluminum oxide increased by adding more alumina to the cell.
_z _ 3~
der normal operating conditions the cell is fed with aluminum oxide regularly, even when no anode effect occurs. Also, whenever the anode effect occurs the crust must be broken open and the al-umina concentra-tion increased by the addition of more aluminum oxide, whlch is called servicing the cell.
For many years now servicing the cell includes breaking open -the crust of solidified melt between the anodes and the side ledge of the cell, and then adding fresh aluminum oxide. This process which is still wiclely practised today is finding increasing cri~
ticism because of the pollution of the air in the po-t room and the air outside. In recent years therefore it has become increas~
ingly necessary and obligatory to hood over or encapsulate the reduc-tion cells and to treat the exhaust gases. It is however not possible to capture completely all the exhaust gases by hood-ing the cells if the cells are serviced in the classical mannerbetween the anodes and the side ledge of -the cells.
More recently therefore aluminum producers have been going over to servicing at the longitudinal axis of the cell. After breaking open the crust, the alumina is fed to the cell ei-ther locally and continuously according to the point feeder principle or dis-continuously along the whole of the central axis o~ the celi.
In both cases a storage bunker for alumina is provided above the cell. The same applies for the transverse cell feeding proposed recently by the applicant (US Patent 4 172 018).
~ ~ 5~ 3 The breaking open of the solidified electrolyte i~
carried out with conventional, well known devices fitted with chisels which are rectangular or round in cross section.
The under part of the chisel which comes into immediate contact with the solidified electrolyte when breaking through the crust is, in the case of the known devices, e.g. vertical to the sidewalls, or is in the form of a cone or blunted cone on the face vertical to the side-walls of the chisel. In Canadian ~atent ~pplication 359,978, filed September 9, 1980, Thomas Haggenmacher et al, a chisel shape providing a stamping or shearing action is described.
When using permanently installed crust breaking facilities an opening of close fit for the chisel is created in the crust as a result of the repeated servicing at relatively short intervals and previous operation of the chisel, i.e., only a very small space exists between the chisel and the crust which is broken open. Depending on the shape of the crust breaker, in particular the chisel, there is a greater or lesser risk of the chisel becoming jammed in this opening in the crust.
It is ther~fore an object of the invention to develop a device for breaking open the crust on an electro-lytic cell and a method for its operation which ensures continuous operation without it jamming.
In one aspect of the invention there is provided a process for breaking the solidified crust on an electro-lytic cell by operating a crust breaker fitted with a chisel which comprises providing a chisel having a vertical sidewall with at least one projection in the lower region of the vertical sidewall, penetrating the crust with said chisel, lowering said chisel further at least until the ~ J~ ~ ~
lowest projection or projections reaches the lower half of the crust.
In another aspect of the invention there is pro-vided a device particularly a chisel for a crust breaking facility for breaking through the solidified crust of an electrolyte on an electrolytic cell, which comprises a chisel having a vertical sidewall and at least one pro-jection in the lower region of the vertical sidewalls of the chisel.
Such projection is usefully of an elongated shape and extends, horlzontally positioned, over at least a part of the periphery of the chisel. However, two or more projections can also be provided in parallel planes; their distance from the under side of the chisel and the distance between each other can be varied according to the geometry of the cell.
The projections are prefera~ly made of the same material as the chisel, in particular a hard, weldable steel e.g. St 45-50. Preshaped projections can be mounted-on the vertical sidewalls of the chisel by suitable methods of fixing e.g. welding or bolting. The projections can also be in the form of weld seams which are finished off by a suitable finishing process. The chisel and projections can be in one piece by e.g. machining the chisel to the appropriate shape. In general the projections are rect-angular in cross section; a square shape is preferred, and they are often slightly undercut on the lower side.
.~ .
.~.1l Sri~
The dimensions of the projection are important: a projection which stands out too far from the chisel is in danger of being deformed; if it stands out too little then it will be ineffective. A distance of 5-15 mm is therefore preferred. In particular the chisel has a cross-sectional dimension wherein all surfaces of the projection or projections extend outwardly substantially less than the cross-sectional dimension`~
The solution according to the invention - taking into account the process in mind - is such that the chisel, with `
1.5~D~
at leas ne proj~ction in the lower re~Jion of its ~idew~11s, after breaking through the crust, is lowered further at least until the lowes-t pro~ection reaches the lower half (in terms of its thickness) of the crust.
S On pressing the projections into the solidiEied electrolyte, the same create a ~ap, which prevents the chisel forming an open-ing which is a close fit for the chisel. If it i5 desired that . the projections push completely through the crust when the chisel is lowered, then these are positioned far down the chisel side-~
walls i.e. near the working face of the chisel. If on the otherhand the projections are required to break through only the upper half of the crust, they are mounted correspondingly further up the chisel walls. It is in fact possible to position these pro-jections even further from the working end i.e. urther up; this is however of little value as the following advantages will not or will only partially be realised as the chisel is lowered the next -time viz., that:
- the chisel does not jam in the crust - the chisel can be withdrawn without difficulty - the forces on the piston rod arrangement can be reduced.
The crust breaker facility which in principle comprises a press-ure cylinder, piston rod and chisel is mounted directly or in-directly on the superstructure of the cell or is a component part of a cell servicing vehicle or manipulator.
5f~
Exemplified embodiments of the invention are described in the following with the help of schematic drawings viz.
Fig. 1: A longitudinal section through a chisel which is rec-tangular in cross section and features pro]ections on its narrow edges, shown here in the lowest working position.
Fig. 2: An end view of the chisel shown in fig. 1.
Fig. 3: A view of a chisel which is round in cross section and~
which features two pairs of projec-tions at different levels and displaced around the circumference with resp-ect to each other.
Flg. 4: A cross section along IV-IV of the chisel shown in fig.3.
Fig~ 5: A longitudinal cross section through part of a chisel with projections of various sizes.
.
Fig. 1 shows a chisel which is an elongated rectangle in cross section, 150 x 140 mm in the case in question. The lower part of the chisel 10 is immersed in the melt 14 i.e. it has completely penetrated the solidified melt 16. This lower part is shown here to be fish-tailed in shape. Although this shape is of advantage, the lower part of the chisel can have any suitable shape.
The lower pair of projections 12 on the narrow side has almost completely penetrated the crus-t. As a result an almost complete and con-tinuous gap 18 has been created between the chisel 10 and the crust. As shown in fig. 1, alumina~ying on the crust 16 is trickling down this gap. This does not cause the chisel 10 to jam, S therefore the chisel 10 can readily be wi-thdrawn after penetrating the crust 16. When the cell is serviced again - which with the automatic systems takes place after a brief interval - the chisel can be introduced without any aifficulty into the ~è-~s hole created by the projections. If the chisel is not exactly centred, it pushes away the residual nose 17 of solidified crust 16 lef~
over from the previous servicing of the cell, and does so withou-t difficulty or any great force.
In embodiments of the invention not lllustrated here Eur-ther pro-jections can be provided on -the broad face of the chisel.
Furthermore, the chisel can also be pushed down further so that the lower pair of projections 12 penetrate the crust cornpletely.
The sidewall of the projections (which are about 1 cm2 in cross section) facing -the bath or the side of the chisel is undercut, preferably at an angle of up to 20. This working face which is inclined upwards towards the chisel causes the projections to act like teeth.
The alumina and the pieces of crus-t broken off by the lower face of the chisel which are pushed il~tO the molten eleotrclyte 14 are omitt d here for the salce of clarity in the figure Figures 3 and 4 show a chisel 22 which is round in cross section.
In this case too it holds that the lower par-t of the chisel, which is conical here, can have an~ other suitable form.
A lower pair of projections 24 extends round the greater par-t of the periphery of the chisel; this can be seen particularly well in fig. 4 which is a hori~ontal section of the chisel shown in fig~ 3. Another pair of projections 26 further up the shaft of~
clro~nd the chisel on the other hand extend r~3~d a relatively small part o the circumference.
Whereas the projections shown in figures 1~4 are characterised not only by their longish shape and their horizon-tal position, but also by their uniform width, fig. 5 shows a part of a longitudinal view through a chisel which has projections of various widths. The lowest projection 30, which acts first on the solidified electrol-yte, is narrow, and the uppermost projection 34 is the widest.
This means that when the crust breaker is put into action, the space created between the chisel and the crust is enlarged in stages from the bottom to the top.
It is understood of course tha-t the projections according to the invention secured to the lower region of the chisel can have many different forms and achieve the same result. The lowest part of the chisel bearing or forming the projections can be in the ~.s~
form of an exchangeable part which is releasably connected to -the shaft of the chisel. This version has the advantage that af-ter a certain degree of wear or when repair is called for, only -the lowest part and not the whole chisel need be changed.
In the manu~acture of aluminum from aluminum oxide the latter is dissolved in a fluoride melt made up for the greater part of cryolite. The aluminwm which separates out at the cathode collects under the fluoride melt on the carbon Eloor of the cell; -the sur-face of this liquid aluminum acts as the cathode. Dipping into the melt from above are anodes which, in the conventional reduc-tion process~ are made of amorphous carbon. As a result of the electrolytic decomposition of the aluminum oxide, oxygen is pro-duced at the carbon anodes; this oxygen combines with the carbonin the anodes to form C02 and CO. The e~ = process takes place in a temperature range of approximately 940-970C.
The concentration of aluminum oxide decreases in the course of the process. At an A12O3 concentration of 1-2 wt.% the so-called anode effect occurs producing an increase in vol-tage from e.g.
4-4.5 V to 30 V and more. Then at the latest the crust mus-t be broken open and the concentration of aluminum oxide increased by adding more alumina to the cell.
_z _ 3~
der normal operating conditions the cell is fed with aluminum oxide regularly, even when no anode effect occurs. Also, whenever the anode effect occurs the crust must be broken open and the al-umina concentra-tion increased by the addition of more aluminum oxide, whlch is called servicing the cell.
For many years now servicing the cell includes breaking open -the crust of solidified melt between the anodes and the side ledge of the cell, and then adding fresh aluminum oxide. This process which is still wiclely practised today is finding increasing cri~
ticism because of the pollution of the air in the po-t room and the air outside. In recent years therefore it has become increas~
ingly necessary and obligatory to hood over or encapsulate the reduc-tion cells and to treat the exhaust gases. It is however not possible to capture completely all the exhaust gases by hood-ing the cells if the cells are serviced in the classical mannerbetween the anodes and the side ledge of -the cells.
More recently therefore aluminum producers have been going over to servicing at the longitudinal axis of the cell. After breaking open the crust, the alumina is fed to the cell ei-ther locally and continuously according to the point feeder principle or dis-continuously along the whole of the central axis o~ the celi.
In both cases a storage bunker for alumina is provided above the cell. The same applies for the transverse cell feeding proposed recently by the applicant (US Patent 4 172 018).
~ ~ 5~ 3 The breaking open of the solidified electrolyte i~
carried out with conventional, well known devices fitted with chisels which are rectangular or round in cross section.
The under part of the chisel which comes into immediate contact with the solidified electrolyte when breaking through the crust is, in the case of the known devices, e.g. vertical to the sidewalls, or is in the form of a cone or blunted cone on the face vertical to the side-walls of the chisel. In Canadian ~atent ~pplication 359,978, filed September 9, 1980, Thomas Haggenmacher et al, a chisel shape providing a stamping or shearing action is described.
When using permanently installed crust breaking facilities an opening of close fit for the chisel is created in the crust as a result of the repeated servicing at relatively short intervals and previous operation of the chisel, i.e., only a very small space exists between the chisel and the crust which is broken open. Depending on the shape of the crust breaker, in particular the chisel, there is a greater or lesser risk of the chisel becoming jammed in this opening in the crust.
It is ther~fore an object of the invention to develop a device for breaking open the crust on an electro-lytic cell and a method for its operation which ensures continuous operation without it jamming.
In one aspect of the invention there is provided a process for breaking the solidified crust on an electro-lytic cell by operating a crust breaker fitted with a chisel which comprises providing a chisel having a vertical sidewall with at least one projection in the lower region of the vertical sidewall, penetrating the crust with said chisel, lowering said chisel further at least until the ~ J~ ~ ~
lowest projection or projections reaches the lower half of the crust.
In another aspect of the invention there is pro-vided a device particularly a chisel for a crust breaking facility for breaking through the solidified crust of an electrolyte on an electrolytic cell, which comprises a chisel having a vertical sidewall and at least one pro-jection in the lower region of the vertical sidewalls of the chisel.
Such projection is usefully of an elongated shape and extends, horlzontally positioned, over at least a part of the periphery of the chisel. However, two or more projections can also be provided in parallel planes; their distance from the under side of the chisel and the distance between each other can be varied according to the geometry of the cell.
The projections are prefera~ly made of the same material as the chisel, in particular a hard, weldable steel e.g. St 45-50. Preshaped projections can be mounted-on the vertical sidewalls of the chisel by suitable methods of fixing e.g. welding or bolting. The projections can also be in the form of weld seams which are finished off by a suitable finishing process. The chisel and projections can be in one piece by e.g. machining the chisel to the appropriate shape. In general the projections are rect-angular in cross section; a square shape is preferred, and they are often slightly undercut on the lower side.
.~ .
.~.1l Sri~
The dimensions of the projection are important: a projection which stands out too far from the chisel is in danger of being deformed; if it stands out too little then it will be ineffective. A distance of 5-15 mm is therefore preferred. In particular the chisel has a cross-sectional dimension wherein all surfaces of the projection or projections extend outwardly substantially less than the cross-sectional dimension`~
The solution according to the invention - taking into account the process in mind - is such that the chisel, with `
1.5~D~
at leas ne proj~ction in the lower re~Jion of its ~idew~11s, after breaking through the crust, is lowered further at least until the lowes-t pro~ection reaches the lower half (in terms of its thickness) of the crust.
S On pressing the projections into the solidiEied electrolyte, the same create a ~ap, which prevents the chisel forming an open-ing which is a close fit for the chisel. If it i5 desired that . the projections push completely through the crust when the chisel is lowered, then these are positioned far down the chisel side-~
walls i.e. near the working face of the chisel. If on the otherhand the projections are required to break through only the upper half of the crust, they are mounted correspondingly further up the chisel walls. It is in fact possible to position these pro-jections even further from the working end i.e. urther up; this is however of little value as the following advantages will not or will only partially be realised as the chisel is lowered the next -time viz., that:
- the chisel does not jam in the crust - the chisel can be withdrawn without difficulty - the forces on the piston rod arrangement can be reduced.
The crust breaker facility which in principle comprises a press-ure cylinder, piston rod and chisel is mounted directly or in-directly on the superstructure of the cell or is a component part of a cell servicing vehicle or manipulator.
5f~
Exemplified embodiments of the invention are described in the following with the help of schematic drawings viz.
Fig. 1: A longitudinal section through a chisel which is rec-tangular in cross section and features pro]ections on its narrow edges, shown here in the lowest working position.
Fig. 2: An end view of the chisel shown in fig. 1.
Fig. 3: A view of a chisel which is round in cross section and~
which features two pairs of projec-tions at different levels and displaced around the circumference with resp-ect to each other.
Flg. 4: A cross section along IV-IV of the chisel shown in fig.3.
Fig~ 5: A longitudinal cross section through part of a chisel with projections of various sizes.
.
Fig. 1 shows a chisel which is an elongated rectangle in cross section, 150 x 140 mm in the case in question. The lower part of the chisel 10 is immersed in the melt 14 i.e. it has completely penetrated the solidified melt 16. This lower part is shown here to be fish-tailed in shape. Although this shape is of advantage, the lower part of the chisel can have any suitable shape.
The lower pair of projections 12 on the narrow side has almost completely penetrated the crus-t. As a result an almost complete and con-tinuous gap 18 has been created between the chisel 10 and the crust. As shown in fig. 1, alumina~ying on the crust 16 is trickling down this gap. This does not cause the chisel 10 to jam, S therefore the chisel 10 can readily be wi-thdrawn after penetrating the crust 16. When the cell is serviced again - which with the automatic systems takes place after a brief interval - the chisel can be introduced without any aifficulty into the ~è-~s hole created by the projections. If the chisel is not exactly centred, it pushes away the residual nose 17 of solidified crust 16 lef~
over from the previous servicing of the cell, and does so withou-t difficulty or any great force.
In embodiments of the invention not lllustrated here Eur-ther pro-jections can be provided on -the broad face of the chisel.
Furthermore, the chisel can also be pushed down further so that the lower pair of projections 12 penetrate the crust cornpletely.
The sidewall of the projections (which are about 1 cm2 in cross section) facing -the bath or the side of the chisel is undercut, preferably at an angle of up to 20. This working face which is inclined upwards towards the chisel causes the projections to act like teeth.
The alumina and the pieces of crus-t broken off by the lower face of the chisel which are pushed il~tO the molten eleotrclyte 14 are omitt d here for the salce of clarity in the figure Figures 3 and 4 show a chisel 22 which is round in cross section.
In this case too it holds that the lower par-t of the chisel, which is conical here, can have an~ other suitable form.
A lower pair of projections 24 extends round the greater par-t of the periphery of the chisel; this can be seen particularly well in fig. 4 which is a hori~ontal section of the chisel shown in fig~ 3. Another pair of projections 26 further up the shaft of~
clro~nd the chisel on the other hand extend r~3~d a relatively small part o the circumference.
Whereas the projections shown in figures 1~4 are characterised not only by their longish shape and their horizon-tal position, but also by their uniform width, fig. 5 shows a part of a longitudinal view through a chisel which has projections of various widths. The lowest projection 30, which acts first on the solidified electrol-yte, is narrow, and the uppermost projection 34 is the widest.
This means that when the crust breaker is put into action, the space created between the chisel and the crust is enlarged in stages from the bottom to the top.
It is understood of course tha-t the projections according to the invention secured to the lower region of the chisel can have many different forms and achieve the same result. The lowest part of the chisel bearing or forming the projections can be in the ~.s~
form of an exchangeable part which is releasably connected to -the shaft of the chisel. This version has the advantage that af-ter a certain degree of wear or when repair is called for, only -the lowest part and not the whole chisel need be changed.
Claims (15)
1. A chisel for a crust breaking facility for break-ing through the solidified crust of electrolyte on an electrolytic cell which comprises a chisel having a vertical sidewall and at least one projection provided in the lower region of the vertical sidewall of the chisel, said chisel having a cross-sectional dimension wherein all surfaces of said at least one projection extend outwardly substantially less than said cross-sectional dimension.
2. A chisel according to claim 1, wherein the at least one projection extends around at least a part of the chisel periphery, is rectangular in cross section, and projects out 5-15 mm from the sidewall of the chisel.
3. A chisel according to claim 2, wherein said at least one projection is square in cross section.
4 A chisel according to claim 1 or 2, wherein the at least one projection is secured in a horizontal position to the sidewalls of the chisel by means of welding or screwing.
5. A chisel according to claim 1 or 2, wherein the at least one projection is weld seams.
6. A chisel according to claim 1 or 2, wherein the at least one projection and the chisel are component parts of the same piece.
7. A chisel according to claim 1 or 2, wherein the face of the projection facing the lower part of the chisel is undercut.
8. A chisel according to claim 1 or 2, wherein the face of the projection facing the lower part of the chisel is undercut at an angle of up to 20°.
9. A chisel according to claim 1 or 2, wherein a plurality of projections on different planes on the chisel sidewall project out equal distances from said sidewall.
10. A chisel according to claim 1 or 2, wherein a plurality of projections on different planes on the chisel sidewall project out from said sidewall by distances which increase from the bottom of the chisel upwards.
11. A chisel according to claim 1 or 2, for breaking through the solidified crust of electrolyte on an electro-lytic cell for producing aluminum.
12. A process for breaking the solidified crust on an electrolytic cell by operating a crust breaker fitted with a chisel which comprises:
providing a chisel having a vertical sidewall with at least one projection in the lower region of the vertical sidewall, said chisel having a cross-sectional dimension wherein all surfaces of said at least one projection extend outwardly substantially less than said cross-sectional dimension, penetrating the crust with said chisel and, lowering said chisel further at least until the lowest projection or projections reaches the lower half of the crust.
providing a chisel having a vertical sidewall with at least one projection in the lower region of the vertical sidewall, said chisel having a cross-sectional dimension wherein all surfaces of said at least one projection extend outwardly substantially less than said cross-sectional dimension, penetrating the crust with said chisel and, lowering said chisel further at least until the lowest projection or projections reaches the lower half of the crust.
13. A process according to claim 12, wherein the at least one projection extends around at least a part of the chisel periphery, is rectangular in cross section, and projects out 5-15 mm from the sidewall of the chisel.
14. A process according to claim 12 or 13, wherein the chisel is lowered further at least until the lowest projection or projections are pushed completely through the crust.
15. A process according to claim 12 or 13, for breaking the solidified crust on an electrolytic cell for producing aluminum.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH8151/79-6 | 1979-09-10 | ||
| CH815179 | 1979-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150189A true CA1150189A (en) | 1983-07-19 |
Family
ID=4335944
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000359982A Expired CA1150189A (en) | 1979-09-10 | 1980-09-09 | Chisel for a crust breaking facility and method for operation of the same |
Country Status (14)
| Country | Link |
|---|---|
| US (2) | US4317595A (en) |
| EP (1) | EP0025418B1 (en) |
| JP (1) | JPS5647582A (en) |
| AT (1) | ATE2551T1 (en) |
| AU (1) | AU539612B2 (en) |
| CA (1) | CA1150189A (en) |
| DE (1) | DE2943291C2 (en) |
| ES (1) | ES8106768A1 (en) |
| GR (1) | GR69698B (en) |
| IS (1) | IS1151B6 (en) |
| NO (1) | NO154173C (en) |
| NZ (1) | NZ194874A (en) |
| YU (1) | YU231080A (en) |
| ZA (1) | ZA805336B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH644156A5 (en) * | 1979-09-10 | 1984-07-13 | Alusuisse | DEVICE FOR OPERATING ELECTROLYSIS OVENS. |
| CN102011149B (en) * | 2010-12-23 | 2015-12-02 | 高伟 | Inflow push-type aluminum oxide feeding device |
| EP3278931A1 (en) * | 2016-08-02 | 2018-02-07 | HILTI Aktiengesellschaft | Flat chisel |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR615512A (en) * | 1927-01-10 | |||
| US1614287A (en) * | 1920-07-17 | 1927-01-11 | Rembrandt Peale | Mining machine |
| AT237909B (en) * | 1962-12-07 | 1965-01-11 | Vmw Ranshofen Berndorf Ag | Electropneumatic device for the automatic periodic addition of alumina in aluminum electrolysis furnaces |
| CH496100A (en) * | 1967-04-07 | 1970-09-15 | Alusuisse | Method and device for operating a furnace for the electrolytic production of aluminum |
-
1979
- 1979-10-26 DE DE2943291A patent/DE2943291C2/en not_active Expired
-
1980
- 1980-08-28 ZA ZA00805336A patent/ZA805336B/en unknown
- 1980-09-01 GR GR62790A patent/GR69698B/el unknown
- 1980-09-05 US US06/184,343 patent/US4317595A/en not_active Expired - Lifetime
- 1980-09-08 NZ NZ194874A patent/NZ194874A/en unknown
- 1980-09-08 IS IS2583A patent/IS1151B6/en unknown
- 1980-09-08 NO NO802645A patent/NO154173C/en unknown
- 1980-09-08 ES ES494888A patent/ES8106768A1/en not_active Expired
- 1980-09-08 AU AU62111/80A patent/AU539612B2/en not_active Ceased
- 1980-09-09 AT AT80810285T patent/ATE2551T1/en not_active IP Right Cessation
- 1980-09-09 EP EP80810285A patent/EP0025418B1/en not_active Expired
- 1980-09-09 CA CA000359982A patent/CA1150189A/en not_active Expired
- 1980-09-10 YU YU02310/80A patent/YU231080A/en unknown
- 1980-09-10 JP JP12586980A patent/JPS5647582A/en active Pending
-
1981
- 1981-11-19 US US06/323,021 patent/US4380492A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| YU231080A (en) | 1983-06-30 |
| DE2943291C2 (en) | 1983-02-10 |
| JPS5647582A (en) | 1981-04-30 |
| DE2943291A1 (en) | 1981-04-02 |
| US4317595A (en) | 1982-03-02 |
| EP0025418B1 (en) | 1983-02-16 |
| NO802645L (en) | 1981-03-11 |
| IS1151B6 (en) | 1984-03-05 |
| AU6211180A (en) | 1981-03-19 |
| GR69698B (en) | 1982-07-08 |
| NO154173B (en) | 1986-04-21 |
| NO154173C (en) | 1986-08-06 |
| AU539612B2 (en) | 1984-10-11 |
| NZ194874A (en) | 1984-12-14 |
| IS2583A7 (en) | 1981-03-11 |
| ATE2551T1 (en) | 1983-03-15 |
| US4380492A (en) | 1983-04-19 |
| EP0025418A1 (en) | 1981-03-18 |
| ES494888A0 (en) | 1981-09-01 |
| ZA805336B (en) | 1981-09-30 |
| ES8106768A1 (en) | 1981-09-01 |
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