
6 Foam Fractionation: Principles and Process Design
In minerals otation, there is the potential to add a further two reagents:
3. An “activator,” which helps the collector selectively adsorb to a par-
ticular particle species, and
4. A “depressant,” which helps prevent the collector from adsorbing to
a particular particle species.
When air is bubbled through the slurry in the “collection zone,” the coal
particles have the opportunity to attach to the bubbles, whence they are trans-
ported up the column and into the foam layer above, known as the cleaning
zone. The hydrophilic ash particles do not attach and most fall through the
slurry to be ...