Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 66.4.4 Valorisation of fluosilicic acidDescriptionThe absorption of SiF 4 in hydrofluoric acid solutions yields a 25 to 35 % fluosilicic acidtechnical grade solution. The possible uses of this product are:• direct use in the fluorination of potable water• production of the hexafluorosilicates of sodium, potassium, magnesium, lead, copper, zinc,ammonium• production of sodium fluoride• production of kryolite (sodium hexafluoroaluminate), potassium hexafluoroaluminate, andaluminum fluoride, for aluminum production• depending on the intended scale, production of HF.Achieved environmental benefitsDisposal of the by-product into the environment is avoided.Cross-media effectsNone believed likely.Operational dataNo information provided.ApplicabilityAs this production is in competition with the by-products originating from glass etching withHF and phosphoric acid production, and as the demand is limited, excess production isneutralised with lime to CaF 2 and SiO 2 , before landfilling.For production of HF from fluosilicic acid, see Section 6.4.10.EconomicsCost benefits.Driving force for implementationCost benefits.References to literature and example plants[22, CEFIC, 2000, 24, Dreveton, 2000, 25, Davy, 2005]Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 271