CH417975A - Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum - Google Patents

Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum

Info

Publication number
CH417975A
CH417975A CH1432462A CH1432462A CH417975A CH 417975 A CH417975 A CH 417975A CH 1432462 A CH1432462 A CH 1432462A CH 1432462 A CH1432462 A CH 1432462A CH 417975 A CH417975 A CH 417975A
Authority
CH
Switzerland
Prior art keywords
aluminum
sodium
production
exhaust gases
fluoride
Prior art date
Application number
CH1432462A
Other languages
German (de)
Inventor
Erwin Dr Moser
Original Assignee
Alusuisse
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 Alusuisse filed Critical Alusuisse
Priority to CH1432462A priority Critical patent/CH417975A/en
Priority claimed from CH4450757A external-priority patent/CH372846A/en
Publication of CH417975A publication Critical patent/CH417975A/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B01D47/06—Spray cleaning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/68—Halogens or halogen compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/48—Halides, with or without other cations besides aluminium
    • C01F7/50—Fluorides
    • C01F7/54—Double compounds containing both aluminium and alkali metals or alkaline-earth metals

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Treating Waste Gases (AREA)

Description

  

  Verfahren zur Gewinnung von Natrium-Aluminium-Doppelfluoriden aus den bei der       elektrolytischen    Herstellung von     Aluminium    entweichenden     HF-haltigen    Ofenabgasen    Das Hauptpatent Nr. 372 846 bezieht sich auf  ein Verfahren zur Gewinnung von Natrium-Alumi  nium-Doppelfluoriden aus den bei der elektrolyti  schen Herstellung von Aluminium entweichenden  HF-haltigen Ofenabgasen und zeichnet sich dadurch  aus, dass man die Abgase mit Wasser auswäscht und  die erhaltene fluorwasserstoffhaltige wässerige Lösung  mit einer solchen Menge Aluminiumhydroxid ver  setzt, dass eine A1F3- und HF-haltige Lösung ent  steht, diese Lösung dann mit Natriumhydroxid oder  Natriumkarbonat versetzt,

   worauf das     Natrium-Alu-          minium-Doppelfluorid    ausfällt.  



  Nach einer weiteren Ausbildung der Erfindung  wird nun die fluorwasserstoffhaltige wässerige Lö  sung mit Aluminiumoxid bzw. Aluminiumhydroxid  und mit Natriumfluorid zur Reaktion gebracht, wobei  Natrium-Aluminium-Doppelfluorid ausfällt.  



  Die der AlF3-Lösung zugesetzte NaF-Lösung  kann z. B. durch Auslaugen von Ofenausbruch und  Umsetzung der damit erhaltenen Soda- und Natron  lauge mit HF-Lösung gewonnen werden. Die Aus  bruchlauge kann auch direkt der HF-sauren     AlF3-          Lösung    zugegeben werden, wobei gleichzeitig mit  der Bildung von NaF Kryolith oder ein anderes  Natrium - Aluminium - Doppelfluorid ausfällt. Mit  Ofenausbruch wird hier das Material bezeichnet, das  aus der     unbrauchbar    gewordenen Auskleidung der  Ofenwanne von Aluminiumelektrolysezellen ausge  brochen wird.

   Es enthält neben Kohlenstoff be  trächtliche Mengen an Na2CO3, NaF, Kryolith  und     A1203.    Je - nach     Zusammensetzung    des Ofen  ausbruches und der Aufschlussmethode ändert das  Verhältnis zwischen Na2CO3, NaOH, NaF- und  Na-Aluminat-Gehalt in der Lösung.    Die NaF-Lösung kann aber auch auf bekannte  Weise dadurch erzeugt werden, dass ein Teil der  Ofenabgase in einer besonderen Anlage mit Soda  lösung oder Natronlauge gewaschen wird. Anstelle  dieser Sodalösung oder Natronlauge kann zu diesem  Zweck auch Ofenausbruchlauge verwendet werden.  



  Ausserdem lässt sich die NaF-Lösung auch da  durch gewinnen, dass die Abgase in einer ersten  Stufe nur unvollständig mit Wasser gewaschen wer  den, so dass in einer zweiten Stufe Fluorwasserstoff  auch noch mit Sodalösung, Natronlauge oder Ofen  ausbruchlauge absorbiert werden kann. Natürlich  kann umgekehrt auch zuerst in einer ersten Stufe       alkalisch    und in einer zweiten mit Wasser gewaschen  werden.



  Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum. The main patent No. 372 846 relates to a process for the production of sodium-aluminum double fluorides from the during the electrolytic production of HF-containing furnace exhaust gases escaping from aluminum and is characterized by the fact that the exhaust gases are washed out with water and the resulting aqueous solution containing hydrogen fluoride is mixed with such an amount of aluminum hydroxide that an A1F3- and HF-containing solution is formed, this solution then with sodium hydroxide or sodium carbonate added,

   whereupon the sodium-aluminum double fluoride precipitates.



  According to a further embodiment of the invention, the aqueous solution containing hydrogen fluoride is now reacted with aluminum oxide or aluminum hydroxide and with sodium fluoride, with sodium-aluminum double fluoride precipitating out.



  The NaF solution added to the AlF3 solution can e.g. B. can be obtained by leaching out of the furnace and converting the soda and sodium hydroxide solution thus obtained with HF solution. The caustic solution can also be added directly to the HF-acidic AlF3 solution, with the formation of NaF cryolite or another sodium-aluminum double fluoride precipitating out at the same time. The term “furnace breakout” refers to the material that is broken out of the unusable lining of the furnace pan of aluminum electrolysis cells.

   In addition to carbon, it contains considerable amounts of Na2CO3, NaF, cryolite and A1203. Depending on the composition of the furnace breakout and the digestion method, the ratio between Na2CO3, NaOH, NaF and Na-aluminate content in the solution changes. The NaF solution can, however, also be generated in a known manner by washing part of the furnace exhaust gases in a special system with soda solution or sodium hydroxide solution. Instead of this soda solution or caustic soda, furnace breakout liquor can also be used for this purpose.



  In addition, the NaF solution can also be obtained by the fact that the exhaust gases are only incompletely washed with water in a first stage, so that in a second stage hydrogen fluoride can also be absorbed with soda solution, sodium hydroxide solution or furnace breakout liquor. Conversely, it is of course also possible to wash with alkaline first in a first stage and with water in a second.

Claims (1)

PATENTANSPRUCH Verfahren zur Gewinnung von Natrium-Alumi nium-Doppelfluoriden aus den bei der elektrolyti schen Herstellung von Aluminium entweichenden HF-haltigen Ofenabgasen, dadurch gekennzeichnet, dass man die Abgase mit Wasser auswäscht und die erhaltene fluorwasserstoffhaltige wässerige Lösung mit Aluminiumoxid bzw. Aluminiumhydroxid und mit Natriumfluorid zur Reaktion bringt, wobei Na- trium-Aluminium-Doppelfluorid ausfällt. PATENT CLAIM A process for obtaining sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum, characterized in that the exhaust gases are washed out with water and the resulting aqueous solution containing hydrogen fluoride is washed with aluminum oxide or aluminum hydroxide and with sodium fluoride brings about the reaction, whereby sodium-aluminum double fluoride precipitates. UNTERANSPRUCH Verfahren nach Patentanspruch, dadurch gekenn zeichnet, dass die fluorwasserstoffhaltige wässerige Lösung zuerst mit Aluminiumoxid oder Aluminium- hydroxid unter Bildung von Aluminiumfluorid zur Reaktion gebracht und dann mit Natriumfluorid ver setzt wird. SUBCLUDED Method according to claim, characterized in that the aqueous solution containing hydrogen fluoride is first reacted with aluminum oxide or aluminum hydroxide to form aluminum fluoride and is then reacted with sodium fluoride.
CH1432462A 1957-04-01 1957-04-01 Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum CH417975A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CH1432462A CH417975A (en) 1957-04-01 1957-04-01 Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH4450757A CH372846A (en) 1957-04-01 1957-04-01 Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum
CH1432462A CH417975A (en) 1957-04-01 1957-04-01 Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum

Publications (1)

Publication Number Publication Date
CH417975A true CH417975A (en) 1966-07-31

Family

ID=25714248

Family Applications (1)

Application Number Title Priority Date Filing Date
CH1432462A CH417975A (en) 1957-04-01 1957-04-01 Process for the production of sodium-aluminum double fluorides from the HF-containing furnace exhaust gases escaping during the electrolytic production of aluminum

Country Status (1)

Country Link
CH (1) CH417975A (en)

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