CaF<SUB>2</SUB>沈殿分離-原子吸光分析による低水素用溶接棒被覆剤ならびに同原料中のFの間接定量

Abstract

An indirect determination of F by atomic absorption spectrophotometry was studied. F was precipitated as CaF2, and Ca in CaF2 which was separated by filtering was determined by atomic absorption analysis.The results are as follows:(1) The addition of excess CaCl2 as a reagent for precipitation decreased the solubility of CaF2 in the solution.(2) The solution was boiled for formation of CaF2, and CeCl3 was added to the solution, after cooling to room temperature F-dissolved in the solution was precipitated as CeF3.(3) When absorbance of Ca2+was measured after HClO4 dryness of CaF2, and CeF3, the presence of Ce3+in CeF3 increased absorbance of Ca2+.(4) The amount of F, when 20 mg or over, recovered by both Ca2+ and Cf3+ was about 96.5% actually, and the amount of F obtained from the absorbance of Ca2+, which was increased by Ce3+, was indicated twice as much as F (about 1.5%) recovered by Ce3+, but the amount of F recovered as CaF2 was about 95%, and as CeF3 was about 1.5%. These values were nearly constant so that the effect of the increase of the absorbance was used in that condition for increase of value of F, and F could be determined as the recovery of about 98%.(5) The method was successfully applied to the determination of F in the coating of the low hydrogen type of electrode, fluorides of alkaline earth metals, and cryolite.