| 摘要 |
PURPOSE:To reduce the escaping amount of F2 and perform evaporation and concentration efficiently without producing any scale by adding the hydroxide of alkaline (earth) metals to the waste water containing borofluoride from solder plating bath or the like, controlling the same to the specific pH and separating the hydroxide then evaporating and concentrating the solution. CONSTITUTION:The hydroxide of alkaline (earth) metals (for example, NaOH, KOH) is added to the waste water containing borofluoride from solder plating bath or the like and its pH is controlled to 8 or more. Next, the hydroxide formed is separated away, after which the waste water is evaporated and concentrated. According to this method, no scale is generated in the concentrated solution and therefore the efficiency of evaporation-concentration treatment may be improved and further the F2 escaping amount in the evaporating vapor may be decreased. |
