Determination of Fluorine in Basic Slag

Study on the chemical analysis of basic slag-V

Abstract

This investigation was undertaken to find rapid and accurate chemical methods for the analysis of basic slag. In the report (V), a simple combustion procedure and an indirect volumetric method were described for the determination of fluorine in basic slag.
Combustion procedure:
0·05 to 0·2g of sample mixed with 0·5g of SiO₂ and 0·5g of V₂O₅ is burned at 1300 to 1400°C With moist oxygen in a combustion tube. (Silver gauze rolls are placed at the exit of this tube). The moist oxygen flow rate is adjusted to approximately 200ml per minute.
After about 60mn., the contents of the absorbers (filled with waten) are transferred to a 500ml Erlenmeyer flask, and titrated immediately to a phenolphthalein end-point with 0·01 N NaOH. Approximately 0·5g of mannitol is added and the titration is again carried out to the same end point.
In direct volumetric method:
Sample of 0·3g are weighed in a beaker. Add 30ml of 1 to 3 acetic acid, and heat it for 1-2mn at about 350°C (CaO is decomposed).
The solution is filtered, and washed with hot water. The residue is dissolved in 10ml of hot 1 to 1 HCl. Dilute to 150ml with water. Heat to boiling and add 30ml of saturated solution of ammonium oxalate. Boil for 3mn. and then determin Ca by conventional volumetric KMnO₄ methods.