Reference number
ISO 5438:1993
ISO 5438:1993
© ISO 2024
ISO 5438:1993
Acid-grade and ceramic-grade fluorspar — Determination of silica content — Reduced-molybdosilicate spectrometric method
Edition 2
1993-03
1993-03
Retirada
Resumen
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).
Ciclo de vida
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Anteriormente
RetiradaISO 5438:1985
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Ahora