The pH control in floatation process used for
refining nonferrous metals such as lead and zinc is one of the most severe
controls. The reasons are, firstly the long dead time system between chemical
feed and pH detection, and secondly the limited allowance of the pH value
required for higher gains of floating metals, or yields. In other words,
it is necessary to reduce the control hunting which is likely to occur in
the dead time system, and also to maintain the pH value within the narrow
range which satisfies the conditions.
Now, great performance have been observed in the applications of Dead Time
Computing Module model JFT2, Math Function Module model JF, and Linearizer
model JFX to this control system for dead time compensation. The outline
of the system is illustrated in the figure below. |
