ISO 9502:1993 PDF Download

The procedure for figuring out how much silica is in metallurgical-grade fluorspar is described in the ISO 9502:1993 standard. The silica content of the standard is determined using a reduced-molybdosilicate spectrometric technique and ranges from 0.2% (m/m) to 30% (m/m).

The process involves utilizing sodium carbonate to perform alkaline fusion on a fluorspar sample. Boric acid is added to the resultant mixture to create fluoride complexes, which are subsequently acidified with hydrochloric acid. The formation of the blue molybdosilicic acid complex includes selective reduction in the next phase. The absorbance at a particular wavelength, usually around 650 nm, is then calculated in order to measure this compound spectrophotometrically.