US3192140A - Removal, by suction, of anodic gases formed in electrolytic cells employed for aluminum production - Google Patents
Removal, by suction, of anodic gases formed in electrolytic cells employed for aluminum production Download PDFInfo
- Publication number
- US3192140A US3192140A US119461A US11946161A US3192140A US 3192140 A US3192140 A US 3192140A US 119461 A US119461 A US 119461A US 11946161 A US11946161 A US 11946161A US 3192140 A US3192140 A US 3192140A
- Authority
- US
- United States
- Prior art keywords
- anode
- crust
- bath
- carbon
- gas
- 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 - Lifetime
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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
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/22—Collecting emitted gases
Definitions
- This invention relates to an improvement in the efiiciency of production of aluminum by electroyltic reduction of alumina dissolved in a molten salt bath, such as cryolite. This is attained by rapid exhaustion of carbon dioxide formed on the carbon anode employed in the process, the exhaustion taking place primarily at a site, or at a plurality of sites, closely adjacent to the surface of a crust formed on the surface of the bath, and also preferably closely adjacent to the sides of the anode carbon block, and consequently as close as feasible to the submerged anodically active surfaces or surface of the anode block.
- the amount of aluminum recovered in such prior processes, per unit of current per unit of time, is less than that theoretically calculated according to Faradays law.
- the ratio between the amount of aluminum recovered and that corresponding to said calculation is defined as the current efliciency, which varies from 83 to 90%, depending upon the type of electroyltic cell employed.
- molten aluminum forms or separates directly upon the cathode surface, which may be horizontal,
- Oxygen separates at the anode, which is formed of carbon or has a carbon surf-ace. The oxygen combines with the anode carbon to form carbon dioxide, primarily.
- This invention is based in part upon the concept that a maximum increase in current efficiency is to be obtained by a maximal rate of exhaustion of carbon dioxide from the bath.
- the movement of gas bubbles at or along the electrode surfaces is controlled, so as to obtain minimal time of contact with said surface, especially the anode surface.
- the exhausting devices are, preferably, positioned closely adjacent the surface of the However, measures taken to bath and adjacent the sides of the anode carbon or anode carbon blocks.
- the invention is generally applicable to all types of furnaces used for electrolysis of alumina in a molten bath, including furnaces having opposed parallel horizontal anode and cathode surfaces, and those having opposed parallel anode and cathode surfaces which are inclined to the vertical, or even vertical.
- the invention has its greatest application to the type of furnace in which the anodic surface is disposed above a lower cathodic surface, more or less horizontally, so that a gas layer may normally tend to form under the anode carbon. Formation of this gas layer is prevented, or minimized, by the action of a closely adjacent aspirating device applying a vacuum, preferably equivalent to a pressure depression of about 1 to 15 mm. of water, and advantageously between 5 and 10 mm. water.
- the drawing illustrates application of the invention to a furnace of this type for electrolysis of alumina in molten cryolite.
- FIG. 1 is a vertical longitudinal section; FIG. 2 being a top view.
- the furnace employs, for example, a Soderberg carbon anode.
- the general features of this type of furnace are well known.
- the carbon anode it is suspended in a pot 25 above a lower cathode structure formed by the carbonaceous bottom 24 of the pot.
- the pot is filled with molten cryolite 11, of alumina is fed thereto.
- the molten aluminum collects on the cathode bottom and is periodically removed.
- the anodecathode distance is adjusted by raising or lowering the anode, to maintain the desired bath temperature.
- a crust 13 of solidified bat-h forms on the top surface, which may be partly covered with alumina (not shown), added as the next charge.
- the gas formed primarily at the anode, is carbon dioxide, as explained above.
- a part of this gas reacts with-metal in the bath, to oxidize the metal. This metal loss is a principal cause of diminished efiiciency of the process, also explained above.
- Beneath the crust 13 is a space 15 in which the anodic gases collect.
- one or-more gas aspirating hoods 5 are connected to the top of the hood, through which the gas is exhausted, by conduit 3 and exhaust pump 1. Any powder removed with the gas is separated at 4, before passage to the main exhaust pipe 21.
- Rod 6 serves as a pneumatic drill, which is oscillated vertically to keep open the hole in the crust shown immediately below head 14.
- the drill may be operated by compressed air supplied by a pipe through a valve (not shown) or by a motor 8 through a crankand-connecting rod system 9.
- At 10 is the sealing gasket for gas-tight reciprocating of the hammer-drill.
- Test cells of 25,000 a. are provided the delivery of each being 14 liters of gas per second.
- the indicated magnitude of the depression, 5-10 mm. Water, is sufficient, that is-to say it would serve nopurpose to go beyond the value of 10 mm.
- the drawing illustrates a cell having a single anode, it will be understood that the invention is applicable to a cell or cells having a plurality of anodes.
- the aspirator or aspirators are disposed adjacent both opposite sides of each anode block.
- the apparatus comprising a carbon anode and a cathode in contact withthe bath, a crust of solidified electrolyte tending to form on the surface of the bath and a gaseous oxide of carbon forming and tending to collect in the space between said crust and the surface of'said bath;
- the improvement comprising hood means having suction means and arrangedso as to apply suction tosaid space suhiciently to lower the pressure at said hood to below atmospheric pressure'and to remove the gaseous oxide of carbon so as to prevent formation of a cushion of said gas against and beneath the surface of said anode, said hood having a gas intake disposed adjacent to the surface of the bath and adjacent a side of the anode, and pneumatic reciproeating hammer-drill means within said hood means at said gas intake to drill a hole in the crust to permit application of said suction.
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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)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT1138860 | 1960-06-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3192140A true US3192140A (en) | 1965-06-29 |
Family
ID=11135111
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US119461A Expired - Lifetime US3192140A (en) | 1960-06-27 | 1961-06-26 | Removal, by suction, of anodic gases formed in electrolytic cells employed for aluminum production |
Country Status (2)
Country | Link |
---|---|
US (1) | US3192140A (fr) |
CH (1) | CH373190A (fr) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3501386A (en) * | 1966-05-17 | 1970-03-17 | Arthur F Johnson | Apparatus and process for the reduction of aluminum |
US3673075A (en) * | 1970-04-24 | 1972-06-27 | Reynolds Metals Co | Alumina reduction system |
US3714002A (en) * | 1970-09-02 | 1973-01-30 | Reynolds Metals Co | Alumina reduction cell and improved anode system therein |
US5045168A (en) * | 1989-07-03 | 1991-09-03 | Norsk Hydro A.S. | Point feeder for aluminium electrolysis cell |
US5108557A (en) * | 1990-10-04 | 1992-04-28 | Northwest Aluminum Company | Ore point feeder and method for soderberg aluminum reduction cells |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2631972A (en) * | 1948-06-28 | 1953-03-17 | Bruno B A Luzzatto | Process and apparatus for the electrolytic production of materials |
DE895379C (de) * | 1942-11-13 | 1953-11-02 | Aeg | Elektrolyseofen fuer Schmelzflusselektrolyse zur Gewinnung des Aluminiums |
US2713024A (en) * | 1959-04-24 | 1955-07-12 | Montedison Spa | Process for the continuous feeding of electrolytic aluminum cells |
US2917441A (en) * | 1955-12-28 | 1959-12-15 | Reading Anthracite Company | Self baking electrode construction |
US2964305A (en) * | 1958-11-20 | 1960-12-13 | Chicago Pneumatic Tool Co | Crust breaking apparatus |
US3006825A (en) * | 1957-12-19 | 1961-10-31 | Electrokemisk As | Method of charging aluminium furnaces |
-
1961
- 1961-06-26 US US119461A patent/US3192140A/en not_active Expired - Lifetime
- 1961-06-26 CH CH744861A patent/CH373190A/fr unknown
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE895379C (de) * | 1942-11-13 | 1953-11-02 | Aeg | Elektrolyseofen fuer Schmelzflusselektrolyse zur Gewinnung des Aluminiums |
US2631972A (en) * | 1948-06-28 | 1953-03-17 | Bruno B A Luzzatto | Process and apparatus for the electrolytic production of materials |
US2917441A (en) * | 1955-12-28 | 1959-12-15 | Reading Anthracite Company | Self baking electrode construction |
US3006825A (en) * | 1957-12-19 | 1961-10-31 | Electrokemisk As | Method of charging aluminium furnaces |
US2964305A (en) * | 1958-11-20 | 1960-12-13 | Chicago Pneumatic Tool Co | Crust breaking apparatus |
US2713024A (en) * | 1959-04-24 | 1955-07-12 | Montedison Spa | Process for the continuous feeding of electrolytic aluminum cells |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3501386A (en) * | 1966-05-17 | 1970-03-17 | Arthur F Johnson | Apparatus and process for the reduction of aluminum |
US3673075A (en) * | 1970-04-24 | 1972-06-27 | Reynolds Metals Co | Alumina reduction system |
US3714002A (en) * | 1970-09-02 | 1973-01-30 | Reynolds Metals Co | Alumina reduction cell and improved anode system therein |
US5045168A (en) * | 1989-07-03 | 1991-09-03 | Norsk Hydro A.S. | Point feeder for aluminium electrolysis cell |
US5108557A (en) * | 1990-10-04 | 1992-04-28 | Northwest Aluminum Company | Ore point feeder and method for soderberg aluminum reduction cells |
Also Published As
Publication number | Publication date |
---|---|
CH373190A (fr) | 1963-11-15 |
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