| 摘要 |
PURPOSE:To considerably control solvent deterioration by carrying out predetermined low temp. operation in recovery of mineral acids from waste acid, with a neutral phosphate type solvent, discharged from pickling of metal with mineral acids including nitric acid and hydrofluoric acid. CONSTITUTION:For example, in pickling of stainless steel or the like a mixt. of nitric acid and hydrofluoric acid is used. Since metal such as iron is dissolved in this pickling soln., and the soln. can not be used repeatedly, it is discharged as waste acid. When the mineral acids are recovered from the waste acid with a neutral phosphate base solvent, by regulating the operation temp. to below 30 deg.C the deterioration loss of the expensive solvent can be reduced remarkably. This method is applicable to a waste soln. contg. Ni, Cr, Co, etc. used in catalyst surface treatment. |
