9
concentrate grade, and lower froth stability improves selec-
tivity [24]. The Bikerman foam stability test is perhaps the
best-known method of quantifying the tenacity of a foam
and has been used in many cases to describe the ‘foamabil-
ity’ of systems [7, 23]. The data from the Bikerman test, for
the frother only tests does not correlate to the strength of
the frother. In addition, when other reagents are added to
the system then the data shows that as the frother increases
in strength, the more stable the froth as would be expected.
Figure 8 shows the delta change in froth stability in
seconds between each frother evaluated with and without
reagents. The data shows that the frother becomes more
stable in the presence of other reagents, viz, collectors
and depressant and corresponds to the collector strength.
Cappuccitti and Nesset describe a ‘strong’ frother as one
that produces large changes in stable froth height relative to
gas hold-up, and a ‘weak’ frother as one that does the oppo-
site[25]. This definition remains somewhat arbitrary in that
it does not link to frother concentration (ppm) directly,
but the notion that a significant slope change occurs at the
CCC (critical coalescence concentration) means that clas-
sification curves for frothers can be readily produced by
conducting tests above and below the region of the frothers
CCC. Operationally, frothers that are stronger will bring
more water into the froth and hence be less selective due
to increased entrainment. The metallurgical indicators have
demonstrated that a stronger frother (more stable frother)
does not necessarily give the best grade and recovery for
that particular ore.
In order to compare different methodologies, viz.,
metallurgical versus simple froth stability tests, Figure 9 was
plotted which shows the mass pull from the bench scale
flotation tests as a function of the froth stability values gen-
erated during froth stability tests. One would expect that
mass pull should increase as the froth stability increases.
However, if the froth is stabilised by the frother but is well
drained, then one might expect to get a stable froth during
froth stability tests but a lower mass pull during metallurgi-
cal tests. This illustrates that there is a strong froth for good
recovery (high froth stability) as well as high drainage to
reduce entrainment (lower mass pull). This was also illus-
trated in the work of McFadzean et al., where it was shown
that certain frother blends could produce froths with both
higher froth stability, but also lower entrainability, when
showing synergistic interactions with the components of
the frother blend [2]. This point also illustrates the danger
of relying on a single, simple technique such as a froth sta-
bility test to draw wide-ranging conclusions.
Figure 8. Delta change in froth stability (s) for Senfroth 200, Senfroth 153 and Senfroth 522
with and without reagents on a Merensky ore
concentrate grade, and lower froth stability improves selec-
tivity [24]. The Bikerman foam stability test is perhaps the
best-known method of quantifying the tenacity of a foam
and has been used in many cases to describe the ‘foamabil-
ity’ of systems [7, 23]. The data from the Bikerman test, for
the frother only tests does not correlate to the strength of
the frother. In addition, when other reagents are added to
the system then the data shows that as the frother increases
in strength, the more stable the froth as would be expected.
Figure 8 shows the delta change in froth stability in
seconds between each frother evaluated with and without
reagents. The data shows that the frother becomes more
stable in the presence of other reagents, viz, collectors
and depressant and corresponds to the collector strength.
Cappuccitti and Nesset describe a ‘strong’ frother as one
that produces large changes in stable froth height relative to
gas hold-up, and a ‘weak’ frother as one that does the oppo-
site[25]. This definition remains somewhat arbitrary in that
it does not link to frother concentration (ppm) directly,
but the notion that a significant slope change occurs at the
CCC (critical coalescence concentration) means that clas-
sification curves for frothers can be readily produced by
conducting tests above and below the region of the frothers
CCC. Operationally, frothers that are stronger will bring
more water into the froth and hence be less selective due
to increased entrainment. The metallurgical indicators have
demonstrated that a stronger frother (more stable frother)
does not necessarily give the best grade and recovery for
that particular ore.
In order to compare different methodologies, viz.,
metallurgical versus simple froth stability tests, Figure 9 was
plotted which shows the mass pull from the bench scale
flotation tests as a function of the froth stability values gen-
erated during froth stability tests. One would expect that
mass pull should increase as the froth stability increases.
However, if the froth is stabilised by the frother but is well
drained, then one might expect to get a stable froth during
froth stability tests but a lower mass pull during metallurgi-
cal tests. This illustrates that there is a strong froth for good
recovery (high froth stability) as well as high drainage to
reduce entrainment (lower mass pull). This was also illus-
trated in the work of McFadzean et al., where it was shown
that certain frother blends could produce froths with both
higher froth stability, but also lower entrainability, when
showing synergistic interactions with the components of
the frother blend [2]. This point also illustrates the danger
of relying on a single, simple technique such as a froth sta-
bility test to draw wide-ranging conclusions.
Figure 8. Delta change in froth stability (s) for Senfroth 200, Senfroth 153 and Senfroth 522
with and without reagents on a Merensky ore