Iron ores — Determination of silicon content — Part 2: Reduced molybdosilicate spectrophotometric method

The method is based on decomposition of the test portion by fusion with sodium tetraborate and treatment with dilute nitric acid, addition of ammonium molybdate to convert silicate into a molybdatosilicate complex, reduction to molybdenum blue with ascorbic acid, and spectrophotometric measurement of the absorbance of the molybdenum blue complex at a wavelength of approximately 600 nm. Applies to silicon contents between 0,1 % and 5,0 % in natural iron ores, iron ore concentrates and agglomerates, including sinter products, especially for ores containing fluorine.