| 摘要 |
PURPOSE:To control the activity of the zinc phosphate treating liquid containing complex hydrofluoric acid as an active material. CONSTITUTION:The treating liquid in a treating vessel 1 is supplied to a mixing vessel 3, and the simple fluoride soln. in a simple fluoride replenishing vessel 2 is supplied to the mixing vessel 3, and the aluminum salt of the complex hydrofluoric acid in the treating liquid is converted to complex hydrofluoric acid, and the HF concn. remaining in a mixed liquid is measured by the metallic silicon electrode meter at a HF concn. measuring part, and a control signal is sent from a control unit 5 to a pump 10 and a flow control part 11 based on an obtained data, and the simple fluoride soln. is supplied to the treating liquid in the treating vessel 1 from the simple fluoride replenishing vessel 2, and the activity of the treating liquid in the treating vessel 1 is recovered and controlled in a prescribed range. |
