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ISO 5438:1993

Acid-grade and ceramic-grade fluorspar — Determination of silica content — Reduced-molybdosilicate spectrometric method

Mar 18, 1993
95.99   Withdrawal of Standard   Mar 3, 2010

General information

95.99     Mar 3, 2010

ISO

ISO/TC 175

International Standard

73.080  

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Scope

The method specified is based on decomposition of a test portion by fusion with sodium carbonate and subsequent acidification with hydrochloric acid in the presence of boric acid to complex fluoride, formation of the molybdosilicic acid complex and selective reduction to the blue molybdosilicic acid complex with addition of tartaric acid to prevent interference from phosphate, spectrometric measurement of the absorbance of the coloured complex at the wavelength of maximum absorption (about 795 nm). Applies to products having silica contents, expressed as SiO2, in the range 0,05 % (m/m) to 4,0 % (m/m).

Life cycle

PREVIOUSLY

WITHDRAWN
ISO 5438:1985

NOW

WITHDRAWN
ISO 5438:1993
95.99 Withdrawal of Standard
Mar 3, 2010