| 摘要 |
Fluorosilicic acid solutions, which normally undergo decomposition when distilled, thereby creating unwanted forms of SiO2, are rendered stable during distillation by providing in the fluorosilicic acid solution an amount of HF which is at least about 10 parts of HF per 36 parts of H2SiF6 and an amount of H2O which is at least about 54 parts of H2O per 36 parts of H2SiF6. The mixture is distilled to remove any excess H2O and excess HF that is present, without encountering formation of SiO2, until an azeotropic solution containing about 36% H2SiF6, about 10% HF and about 54% H2O is reached. The ternary azeotrope, being of constant quality and concentration, is more suitable for use in various processes, such as processes for making fumed SiO2, than H2SiF6 solutions which are not of constant quality or concentration. |
