| 摘要 |
PURPOSE:To reduce the running cost by feeding washing water to the 2nd washing vessel without feeding washing water to the 3rd washing vessel in three washing stages and by restricting the amount of washing water to be fed to a specified range. CONSTITUTION:A material to be treated is pretreated with a pretreating soln. in a degreasing vessel 1, and it is successively washed with water in the 1st washing vessel 2, the 2nd washing vessel 3 and the 3rd washing vessel 4. The concn. of the chemical soln. sticking to the surface of the material is successively reduced from C0 to C3, and after attaining a prescribed dilution ratio C0/C3, the material is transferred to the next chemical conversion stage. At this time, the amount X of washing water to be fed to the 3rd washing vessel 4 is made zero, and a required amount Y of washing water is fed to the 2nd washing vessel 3. The prescribed dilution ratio C0/C3 is attained by the amount Y. |
