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 PDF

Info

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
Application number
US119461A
Other languages
English (en)
Inventor
Zorzenoni Guglielmo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Montedison SpA
Original Assignee
Montedison SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Montedison SpA filed Critical Montedison SpA
Application granted granted Critical
Publication of US3192140A publication Critical patent/US3192140A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • C25C3/22—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.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
US119461A 1960-06-27 1961-06-26 Removal, by suction, of anodic gases formed in electrolytic cells employed for aluminum production Expired - Lifetime US3192140A (en)

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)

* Cited by examiner, † Cited by third party
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)

* Cited by examiner, † Cited by third party
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

Patent Citations (6)

* Cited by examiner, † Cited by third party
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)

* Cited by examiner, † Cited by third party
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

Similar Documents

Publication Publication Date Title
US2273795A (en) Electrolytic process
US3578580A (en) Electrolytic cell apparatus
CN101368282A (zh) ***极稀土金属电解槽及采用该电解槽的电解工艺
CN1492949A (zh) 用于生产金属的方法和电解沉积槽
CA1069462A (fr) Methode d'utilisation de cellules electrolytiques a electrodes horizontales
GB1169012A (en) Furnace and Process for Producing, in Fused Bath, Metals from their Oxides, and Electrolytic Furnaces having Multiple Cells formed by Horizontal Bipolar Carbon Electrodes
US3192140A (en) Removal, by suction, of anodic gases formed in electrolytic cells employed for aluminum production
CN114599820A (zh) 熔融盐膜电解槽
CN102605383B (zh) 一种氢循环电解方法和装置及其在氧化铝生产的应用
US7879220B2 (en) Method and means for improving electrolysis cell operation
CN205616961U (zh) 一种纯铝阴极低能耗铝电解槽
ES8403984A1 (es) Cuba de electrolisis para la produccion de aluminio.
CN105780055B (zh) 以铝作为阴极的铝电解槽
US4597839A (en) Method and apparatus for production of a metal from metallic oxide ore
GB962599A (en) Electrolytic furnace for aluminium production
CN210826386U (zh) 一种镁电解槽
JPS5834553B2 (ja) Ｚ↓ｒ又はＨ↓ｆ生成用電解槽
CN85100748A (zh) 一种连续电解生产金属钕及钕铁合金的槽型结构
CN1831198A (zh) 一种用于铝电解惰性阳极焙烧启动或预热更换的保护装置
US3692645A (en) Electrolytic process
CA1289509C (fr) Methode de galvanoplastie economisant l'energie
US3486994A (en) Process for preparing chlorine by electrolysis of aqueous hydrochloric acid
US4601804A (en) Cell for electrolytic purification of aluminum
CN213680928U (zh) 一种抗氧化的预焙阳极
US2448262A (en) Metal cleaning