RI 7213 Recovery Of Hydrofluoric Acid From Waste Fluosilicic Acid - Preliminary Studies

Preliminary studies showed that direct hydrolysis of H2SiF6 to SiO2 and HF at elevated temperatures was subject to many mechanical difficulties, and that corrosion of construction materials was a serious problem. Elimination of SiO2 from the HF product was generally poor. An alternative procedure, hydrolysis of lime-neutralized H2SiF6 by steam at 950° to 1,100° C, yielded a product very low in SiO2. Condensates containing up to 300 g/1 HF were prepared.