ISO 1693:1976 Preview

Cryolite, natural and artificial -- Determination of fluorine content -- Modified Willard-Winter method

Specifies the determination for natural and synthetic materials having a molar ratio sodium fluoride/aluminium trifluoride between 3 and 1,7 approximately. The principle consists in fusion of a test portion with sodium carbonate, separation of fluorine by distillation with sulphuric acid or perchloric acid. Titration with thorium nitrate solution in presence of sodium alizarinsulphonate/methylene blue as indicator. Alternatively, the thorium nitrate titration may be made using only sodium alizarinsulphonate, the end-point being*spectrophotometrically determined at 525 nm.


General information

  • Current status : Published
    Publication date : 1976-09
  • Edition : 1
    Number of pages : 6
  • :
    ISO/TC 226
    Materials for the production of primary aluminium
  • 71.060.50
    Salts

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