PROCEDEU DE OBTINERE A ACIDULUI FLUORHIDRIC ANHIDRU

摘要

Conc. aq. H2SiF6 contg. 40-50% H2SiF6 is decomposed by boiling with 93-98% H2SO4 to give a gas contg. H2O, HF, and SiF4 which is partially dried with H2SO4 and from which HF is absorbed in a circulating stream of H2SO4/HSO3F. The SiF4 is absorbed in dilute (18%) aq. H2SiF6 to provide conc. soln. after removal of SiO2 ppte. Product contains 99.9% HF, 0.02% H2SO4, 0.04% H2O, and 0.03% SiF4 and is obtd. by distn. of mixt. with H2SO4/HSO3F. Spent H2SO4 from process contains 75.5% H2SO4 and 0.15% HF at a rate of e.g. 1340 kg/h for HF production rate of e.g. ca. 40 kg/h. Under these conditions 60 kg/h 22% oleum is required to keep water content of H2SO4/HSO3F absorbent at required level.