By attacking the iron ore with nitric acid and hydrofluoric acid, all the phosphorus present is oxidized to phosphoric acid, while the silica is fed as silicon tetrafluorides. Phosphoric acid is precipitated in the ammonium phosphomolybdate state. The precipitate, washed, is dissolved in an excess of titrated solution of sodium hydrate which is titrated with titrated solution of nitric acid. Solutions and reagents. Method. Try it blank. Calculation.
UNI 3623-1955 history
1955UNI 3623-1955 Procedures for chemical analysis of minerals. Determination of phosphorus in iron ore. Alkalimetric method, for standard analyses.