Norm

ISO 4277:1977 en

Cryolite, natural and artificial - Conventional test for evaluation of free fluorides content

  • Deze norm is ingetrokken sinds 30-10-2009

31,57

Over deze norm

Status Ingetrokken
Aantal pagina's 3
Gepubliceerd op 01-11-1977
Taal Engels
Applicable to products having contents of AlF3 of more than 0.15 % (m/m) or of NaF of more than 0.4 % (m/m). Covers sintering of a test portion with a known quantity of sodium fluoride in a muffle furnace at a temperature of (790 10) °C. Under these conditions, aluminium fluoride in excess of that required by the stoichiometric formula AlF3 .3NaF reacts to form cryolite; extraction of the ground sintered mass with boiling water. Acidification with hydrochloric acid solution to a pH less than 3.7 and titration of the excess sodium fluoride with thorium nitrate solution in the presence of alizarin-S as indicator. Has also been approved by the IUPAC.

Details

ICS-code 71.060.50
Nederlandse titel Cryolite, natural and artificial - Conventional test for evaluation of free fluorides content
Engelse titel Cryolite, natural and artificial - Conventional test for evaluation of free fluorides content
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