ISO 9502:1993

Metallurgical-grade fluorspar — Determination of silica content — Reduced-molybdosilicate spectrometric method ISO 9502:1993

Publication date:   Mar 18, 1993

Scope

The principle of the method specified is to decompose a test portion by alkaline fusion with sodium carbonate and subsequent acidification with hydrochloric acid in the presence of boric acid to complex fluoride, selective reduction to the blue molybdosilicic acid complex, spectrometric measurement of the absorbance of the coloured complex at a wavelength corresponding to the absorption maximum of approximately 650 nm. Applies to products having silica contents, expressed as SiO2, in the range 0,2 % (m/m) to 30 % (m/m).