US3907651A - Method for the molten salt electrolytic production of metals from metal chlorides and electrolyzer for carrying out the method - Google Patents

Method for the molten salt electrolytic production of metals from metal chlorides and electrolyzer for carrying out the method Download PDF

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Publication number
US3907651A
US3907651A US437608*A US43760874A US3907651A US 3907651 A US3907651 A US 3907651A US 43760874 A US43760874 A US 43760874A US 3907651 A US3907651 A US 3907651A
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metal
electrolysis
electrolyzer
zone
cathode
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Expired - Lifetime
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US437608*A
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English (en)
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Knut Anton Andreassen
Kjell Bjorn Stiansen
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Norsk Hydro ASA
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Norsk Hydro ASA
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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
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/04—Electrolytic production, recovery or refining of metals by electrolysis of melts of magnesium

Definitions

  • This invention relates to a method for the molten salt electrolytic production of metals from metal chlorides, and more particularly a method of producing magnesium and chlorine from molten salt containing magnesium chloride. Further, the invention relates to an electrolyzer having double-acting cathodes for carrying out the method.
  • the electrolyte In the ordinary production of magnesium by molten salt electrolysis of magnesium chloride, the electrolyte circulates in a closed loop between the electrolyzing zone and what may be called the outside-lying zones. This natural circulation is probably essentially due to the gas lift effect.
  • One of the main requirements for carrying out the magnesium chloride electrolysis and for the constructional design of Mg electrolysis cells therefor is that the two products, magnesium and chlorine, should be collectable with a minimum of loss. Since recombination of the products is an obvious source of possible loss, it is considered highly important to prevent this by aiming at rapid and complete separation of magnesium and chlorine.
  • the gas is first removed from the electrolyte/metal mixture in a gas separation zone and the metal is then removed from the electrolyte in a metal separation zone.
  • an electrolyzer having a plurality of cells has a number of gas and metal collecting zones.
  • Electrolyzers which work according to this principle comprise three main zones, the electrolysis zone, gas separation zone and metal separation zone.
  • the term gas separation zone is herein intended to mean the zone at the cathode top or immediately above the cathodes. In this zone, the upward flow of molten salt is drastically deflected, as further described below.
  • the two first-mentioned zones are in principle separated from the last-mentioned zone by a partition wall.
  • This partition wall has openings at its lower end to allow the electrolyte to flow into the electrolysis zone. Further, openings are provided at the upper end, although below the surface of the electrolyte, through which openings electrolyte and magnesium metal formed can flow from the gas separation zones into the metal collection zone.
  • An electrolyzer of this type is shown and described in Norwegian Pat. No.
  • This solution has a number of obvious weak nesses.
  • Metal which is produced at sites remote from the opening will have a relatively long residence time in an electrolyte full of gas with a consequent increased risk of recombination.
  • the main flow of electrolyte in the electrolysis zone is diagonal so that the gas is to a great extent moved towards the partition wall and can readily follow the electrolyte through the opening.
  • There is small possibility of controlling the velocity of the electrolyte in front of and in the opening so that it is difficult to achieve a sufficient difference between the gas bubble and electrolyte velocity vectors and a resulting efficient separation of gas from electrolyte and metal.
  • the purpose of the present invention is to effect an accumulation of the two main products magnesium and chlorine in a low number of zones with a minimum of loss due to recombination thereof, providing a rapid and complete separation of gas and metal. More particularly then, a purpose of the invention is to provide a method rendering an extensive possibility of varying flow velocities in the critical region in which gas separation is to take place.
  • the metal together with the electrolyte are separated from the rising stream of chlorine gas by being deflected in a direction substantially opposite to the direction of the rising gas bubbles, the metal and electrolyte being made to flow, utilizing the natural convection, through openings or ducts provided in each cathode, such duets terminating at or in the adjacent metal separation or collection zone, whereupon the electrolyte continues to circulate into the electrolysis zones through openings provided near the bottom of the clectrolyzer, the separated metal rising to the surface of the metal collection zone, as known per se.
  • the invention also relates to an clectrolyzer for carrying out the method and having double-acting cathodes and a partition wall between the electrolysis and gas separation zones on one side and the metal separation zone on the other, there being provided in each cathode one or more ducts which provide communication between gas separation zones and the metal separation zone.
  • the inlet openings of the ducts are preferably located in the horizontal plane of the cathode tops, the outlet openings being located in the vertical plane of the partition wall.
  • the method of the invention results in that the flow in the electrolysis zone, that is the space between anode and cathode, will be substantially in a vertically upward direction. There is no tendency to produce a diagonal flow. Basically this is the most correct flow pattern, that which will remove gas and metal from that zone in a minimum of time.
  • the electrolyte and metal flow make a 180 turn and continue vertically downward. Basically this is the best solution in order to rapidly and completely remove gas from the liquid.
  • the electrolyte and metal flow then continues within the cathode towards the metal separation zone without interfering with the conditions in the electrolysis and gas separation zone.
  • the choice of site and shape of the inlet opening of the duct enables a high degree of control of flow velocities in the gas separation zone to be achieved.
  • the velocities can be adjusted so that the metal will quickly be removed from the gas separation zone by the electrolyte while the gas is retained.
  • the construction results in that the whole region above the cathode functions as a gas separation zone as contrasted to cells having the usual window opening.
  • the rapid and efficient separation of gas from electrolyte/metal mixture achieved by the invention provides a number of possible advantages.
  • Reduced transfer of gas into the metal collection zone means a lower actual loss of gas and reduces pollution problems caused by such loss of gas.
  • FIG. 1 is a horizontal section of an clectrolyzer having double-acting cathodes according to the invention.
  • FIG. 2 is a vertical section along the line AA in FIG. 1.
  • FIG. 3 is a vertical section along the line B-B in FIG. 2.
  • Anodes l and cathodes 2 are arranged alternately so that both electrode types are double-acting.
  • the electrolysis zone is shown by designation numeral 3, the gas separation zone by 4 and the metal separation zone by 5.
  • the duct 6 in the hollow cathode has an inlet at 7 and an outlet at 8.
  • the inlet opening of the duct is located in the horizontal plane of the cathode top, while the outlet opening is located in the vertical plane of the partition wall 10.
  • the cathode is supported by supporting plate 9.
  • a sloping top edge of the cathodes 2 is indicated at 11 where the cathodes extend under the partition 10, and at 12, the internal cathode bottom is showed to be sloping.
  • the flow pattern of the coil construction is indicated by arrows.
  • the electrolyte flows, together with the gas and metal formed at the cathode, vertically upward in the electrolysis zone 3.
  • the electrolyte/metal flow makes a 180 turn to flow vertically downward into the duct 6 provided in the cathode 2.
  • the electrolyte/metal flow makes a 90 turn before entering into the metal separation zone 5. In the latter, the metal separates out, rises to the surface of the electrolyte to remain there. The electrolyte flows downward, turns to flow under the electrodes and from there returns to the electrolysis zone 3.
  • the elec'trolyzer shown in FIGS. 1-3 only represents a preferred embodiment of an eleetrolyser to be used for carrying out the method of the invention in practice and that other constructions and modifications can be employed which provide a suitable relationship of the parameters having an influence upon the flow pattern.
  • the cathodes can be provided with a number of ducts and their inlet openings as well as their outlet openings at the metal separation zone can be varied to suit the flow pattern desirably aimed at To show the practical value of the invention, large scale operation tests were carried out using electrolysis cells with and without hollow cathodes.
  • Example II The test of Example I was repeated except that an electrolyzer was employed having conventional solid cathodes and having window openings in the partition wall at electrolyte surface level for the electrolyte to flow into the metal collection chamber. Results:
  • said passage means comprises at least one duct in each said electrode, each said duct having an inlet opening in the top ofthe respective said electrode; and said step of defleeting comprises passing said electrolyte and metal downwardly through said inlet openings.
  • each cathode having opposite exterior electrolytically active surfaces, said opposite surfaces of each cathode facing corresponding electrolytically active surfaces of separate of said alternately arranged anodes;
  • At least one gas separation zone positioned above and in communication with said electrolysis zones
  • electrolysis zones extend substantially vertically to said gas separation zone, the flow of electrolyte, gas and metal within each electrolysis zone being substantially vertically upwardly.
  • each said passage means comprises at least one duct extending through the respective said cathode and includes means for directing said electrolyte and metal substantially vertically downwardly in a direction opposite to the vertical upward direction of movement of said gas.
  • each said duct has an inlet opening at the top of the respective said cathode.
  • each said electrode comprises a double-walled hollow member with a U-shaped cross section, said member having an open top comprising said inlet opening, said member extending through said partition, each said duet having an outlet opening in a vertical plane of said partition.
  • each said member at the portion thereof extending through said partition, has an inclined surface forming a ceiling of said outlet opening.
  • each said member has a bottom wall inclined towarc said partition and forming a bottom portion of the respective said duct.

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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)
US437608*A 1973-01-30 1974-01-29 Method for the molten salt electrolytic production of metals from metal chlorides and electrolyzer for carrying out the method Expired - Lifetime US3907651A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NO00371/73A NO130119B (enrdf_load_stackoverflow) 1973-01-30 1973-01-30

Publications (1)

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US3907651A true US3907651A (en) 1975-09-23

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US437608*A Expired - Lifetime US3907651A (en) 1973-01-30 1974-01-29 Method for the molten salt electrolytic production of metals from metal chlorides and electrolyzer for carrying out the method

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US (1) US3907651A (enrdf_load_stackoverflow)
JP (1) JPS5332765B2 (enrdf_load_stackoverflow)
BR (1) BR7400636D0 (enrdf_load_stackoverflow)
CA (1) CA1034531A (enrdf_load_stackoverflow)
DD (1) DD110671A5 (enrdf_load_stackoverflow)
ES (1) ES422735A1 (enrdf_load_stackoverflow)
FR (1) FR2215484B1 (enrdf_load_stackoverflow)
GB (1) GB1430351A (enrdf_load_stackoverflow)
IL (1) IL44087A (enrdf_load_stackoverflow)
IS (1) IS2190A7 (enrdf_load_stackoverflow)
NL (1) NL7401184A (enrdf_load_stackoverflow)
NO (1) NO130119B (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4058448A (en) * 1976-06-23 1977-11-15 Muzhzhavlev Konstantin Dmitrie Diaphragmless electrolyzer for producing magnesium and chlorine
EP0027016A1 (en) * 1979-09-27 1981-04-15 Hiroshi Ishizuka Improvement in an apparatus for electrolytic production of magnesium metal from its chloride
US4514269A (en) * 1982-08-06 1985-04-30 Alcan International Limited Metal production by electrolysis of a molten electrolyte
US4518475A (en) * 1982-06-14 1985-05-21 Alcan International Limited Apparatus for metal production by electrolysis of a molten electrolyte
WO2003062496A1 (en) * 2002-01-24 2003-07-31 Northwest Aluminum Technology Low temperature aluminum reduction cell

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO139865C (no) * 1977-06-06 1979-05-23 Norsk Hydro As Utskiftbar katodeenhet egnet som modul for oppbygging av stabile, ikke deformerbare katodesystemer i elektrolysoerer for fremstilling av magnesium samt elektrolysoer med innmonterte katodeenheter
JP4975244B2 (ja) * 2004-08-20 2012-07-11 東邦チタニウム株式会社 溶融塩電解による金属の製造方法および製造装置
RU2284372C1 (ru) * 2005-03-03 2006-09-27 Открытое Акционерное Общество "Корпорация Всмпо-Ависма" Электролизер для получения магния и хлора

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2393686A (en) * 1942-02-06 1946-01-29 Mathieson Alkali Works Electrolytic production of magnesium
US3374163A (en) * 1962-11-15 1968-03-19 Ciba Ltd Cell for electrolysis with molten salt electrolyte
US3749660A (en) * 1971-02-10 1973-07-31 A Kolomiitsev Electrolyzer for production of magnesium

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2393686A (en) * 1942-02-06 1946-01-29 Mathieson Alkali Works Electrolytic production of magnesium
US3374163A (en) * 1962-11-15 1968-03-19 Ciba Ltd Cell for electrolysis with molten salt electrolyte
US3749660A (en) * 1971-02-10 1973-07-31 A Kolomiitsev Electrolyzer for production of magnesium

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4058448A (en) * 1976-06-23 1977-11-15 Muzhzhavlev Konstantin Dmitrie Diaphragmless electrolyzer for producing magnesium and chlorine
EP0027016A1 (en) * 1979-09-27 1981-04-15 Hiroshi Ishizuka Improvement in an apparatus for electrolytic production of magnesium metal from its chloride
US4518475A (en) * 1982-06-14 1985-05-21 Alcan International Limited Apparatus for metal production by electrolysis of a molten electrolyte
US4560449A (en) * 1982-06-14 1985-12-24 Alcan International Limited Metal production by electrolysis of a molten electrolyte
US4514269A (en) * 1982-08-06 1985-04-30 Alcan International Limited Metal production by electrolysis of a molten electrolyte
WO2003062496A1 (en) * 2002-01-24 2003-07-31 Northwest Aluminum Technology Low temperature aluminum reduction cell

Also Published As

Publication number Publication date
DE2404365A1 (de) 1974-08-22
NO130119B (enrdf_load_stackoverflow) 1974-07-08
IL44087A (en) 1976-09-30
IS2190A7 (is) 1974-03-08
DD110671A5 (enrdf_load_stackoverflow) 1975-01-05
BR7400636D0 (pt) 1974-09-10
FR2215484A1 (enrdf_load_stackoverflow) 1974-08-23
ES422735A1 (es) 1976-04-01
DE2404365B2 (de) 1976-08-19
IL44087A0 (en) 1974-05-16
NL7401184A (enrdf_load_stackoverflow) 1974-08-01
CA1034531A (en) 1978-07-11
JPS49106417A (enrdf_load_stackoverflow) 1974-10-09
GB1430351A (en) 1976-03-31
JPS5332765B2 (enrdf_load_stackoverflow) 1978-09-09
FR2215484B1 (enrdf_load_stackoverflow) 1976-11-26

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