3.1.2. Dynamic froth studies three-phase system
In the three phase frothing studies, the froth height was only
measured in the glass column at the maximum gas flow rate of 2 l/min.
The maximum froth volume values obtained in absence and presence of
solids are plotted on Fig. 4.
The results show that the mixture of chalcopyrite and pyroxene
enhanced the froth formation in the case when only frother was present
in solution. However, the solids seem to inhibit frothing when
depressants are also added to the system. This phenomenon could be
observed in case of both polysaccharides, independently of their type.
The appearance of the three-phase froth had the same character
as the foams formed in the two-phase system. The bubbles forming
the frother–guar froth were larger in size and were separated by
thinner liquid films than in case of the frother–CMC blend. Mostly the
top part of the froth formed by the frother–guar blend was much
lighter in color than in the case of the frother–CMC blend, suggesting
that there were fewer chalcopyrite particles present. This might be
attributed to the strong depressing effect of the guar. However it is
more likely that it is caused by the changed rheology of the liquid that
enhances draining, and coalescence of the bubbles, so inhibiting
the transport of the particles into the top layer of the froth. The
Polyederschaum type of froth structure on the upper part of the froth
was clearly visible when guar was added to the system, indicating a
gas content of over 50–75%. The DF200-CMC froth on the other hand
had much higher liquid and solid content resulting in a darker,
mineralized froth.
3.1.3. Static foam/froth studies in two and tree phase systems
The overview of the results of the static foam collapse tests done with
the frother alone and the frother–depressant blends in the glass column,
are presented on Fig. 5a. There is a striking difference in the behavior of
the reagent blends when it comes to the issue of foam stability.