Determination of CO₂ Contents in Slags and Molten Salts by B₂O₃ Fusion and KBF₄ Fusion Methods

Abstract

Two methods have been developed for the determination of the CO₂ contents (carbonate ion contents) in oxide-containing melts. They are the B₂O₃ fusion method and the KBF₄ fusion method. The latter is applicable to chloride melts. The methods consist of two simple procedures: (1) fusion of a sample with B₂O₃ or KBF₄ to evolve CO₂ from the sample, and subsequently (2) determination of the amount of the evolved CO₂ by the weight loss method or using a commercially available carbon analyzer. The present methods have been used to determine the solubility of CO₂ in the Na₂O–SiO₂ system at 1473 K under 101325 Pa of CO₂ and in the NaCl–Na₂O system at 1073 K under 101325 Pa of CO₂. The present methods were found to be successfully applicable even to melts where the thermobalance method is inapplicable because of the low solubilities of CO₂ or the evaporation losses of the melts.