Interaction between SiO2 and a KF–KCl–K2SiF6 Melt

The solubility mechanism of silica in a fluoride–chloride melt has been determined in situ using Raman spectroscopy. The spectroscopy data revealed that the silica solubility process involved Si–O bond breakage and Si–F bond formation. The process results in the formation of silicate complexes, fluorine-bearing silicate complexes, and silicon tetrafluoride in the melt. Mass spectrometry of the vapor phase over the KF–KCl–K2SiF6 and KF–KCl–K2SiF6–SiO2 melts and differential scanning calorimetry coupled with thermal gravimetric analysis of these melts were performed to verify the silica solubility mechanism.