| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for recovering hydrofluoric acid, which is a batch-type hydrofluoric acid recovery method for recovering purified hydrofluoric acid from a hydrofluoric acid waste solution discharged from the etching process of a glass substrate, or the like by a distillation method, and by which production of scales is completely suppressed and the purified hydrofluoric acid containing further reduced impurities can be recovered in a high yield, and with which it is possible to simplify an apparatus. SOLUTION: In the method for recovering the hydrofluoric acid, crude hydrofluoric acid is taken out as vapor by heating a hydrofluoric acid waste solution in an evaporation pot (1), and at the same time, in recovery operations for recovering distillates by distilling the crude hydrofluoric acid with a distillation tower (2), the distillate is recovered as recovery water when the concentration of hydrogen fluoride in the distillate is not higher than the upper limit of the concentration of hydrogen fluoride in the recovery water, the distillate is recovered as an intermediate solution when the concentration of hydrogen fluoride in the distillate is not lower than the upper limit of the concentration of hydrogen fluoride in the recovery water and lower than the concentration of hydrogen fluoride in the hydrofluoric acid to be recovered, and the distillate is recovered as the purified hydrofluoric acid when the concentration of hydrogen fluoride in the distillate is not lower than the concentration of hydrogen fluoride in the hydrofluoric acid to be recovered. Further, in the method, sulfuric acid is added to the hydrofluoric acid waste solution of the distillation tower (2) in an amount sufficient to suppress the deposition of metal components. COPYRIGHT: (C)2006,JPO&NCIPI
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