2
Frother selection plays a critical part in the froth zone
characterisation during flotation. Frothers must prevent
bubble coalescence in the pulp phase, be sufficiently stable
to support the weight of the mineral, stabilise the froth and
allow drainage of water and entrained gangue minerals to
the pulp, ensure mobility and not be so stable that the froth
does not break down in the launders. Frothers can also
increase flotation kinetics.
Moyo discusses frother characterisation techniques,
which look at certain froth characteristics that play a role
in frother performance [5]. A number of methods over the
years have been developed to assess foam formation, one of
the most simple being measurement of the maximum froth
height achieved at a given superficial gas velocity [6, 7, 8, 9,
10]. Iglesias et al. modified Bikerman’s method by switching
off gas once the dynamic equilibrium height was reached
[11]. The decay of foam volume was measured with time.
This parameter was used to characterize the persistence of
the foam produced from a solution of known concentra-
tion. McLaughlin et al. used almost the same method as
Iglesias et al., however, introduced an induction time (time
elapsed between air termination and the start of froth col-
lapse) and used this as the characterizing parameter instead
[12, 11]. Their method was used on three phase froths. Xu
et al. proposed a new method of evaluating froth stability
and foamability [13]. Their adjustment of the technique
was based on their understanding that when frothers are
compared at the same concentration they will produce dif-
ferent froth heights and hence different froth stabilities. In
general, two types of tests are used, dynamic and static tests.
In a dynamic test, air is supplied continuously and foam is
allowed to grow until steady state is reached where the rate
of formation is in equilibrium with rate of decay (bubble
bursting). In static tests, the rate of foam formation is zero:
once the foam is formed, it is allowed to collapse without
further gas input or agitation.
Barbian et al. highlights the crucial role frothers play
in PGM and sulphide ore flotation recovery, where they
evaluated the effect of various frothers, with the optimal
frother-collector combination, on 4E PGM recovery by
means of laboratory batch flotation tests and a subsequent
plant trial [14]. They discussed how challenging it was to
measure froth stability quantitatively, both at laboratory
and at industrial scales. They used a quantitative dynamic
stability measure, based on the Bikerman foam test using a
non-overflowing froth column to quantify froth stability.
At laboratory scale, the froth stability measured agreed very
closely with other methods, and could be related to flota-
tion performance. The metallurgical results clearly indicated
that changes in air rate, froth depth and frother concentra-
tion result in variation in flotation performance that can be
attributed to changes in froth stability. The results showed
that high froth stability conditions occur at intermediate air
flowrates, and result in improved flotation performance. It
was found that the froth stability column is an accurate and
cost-effective method for quantifying froth stability, and for
indicating changes in flotation performance. However, the
data obtained from the ‘Bikerman’ type testwork may not
be always transferrable to the metallurgical performance
indicators as shown during the frother study described in
this paper.
Khoshdast et al. revealed that the 2D froth structure
measurement methods are associated with a considerable
bias, while 3D techniques can effectively represent the
actual froth properties [15]. It was also found that the
potential interactions between various frothers properties
and how they can influence the flotation performance in an
industrial environment are not yet understood and needs
further investigation.
Corin et al. as well as Farrokhpay and Zanin, studied
the effect of an increase in the ionic strength of plant water
on the stability of the froth [16, 17]. Their data showed that
an increase in the ionic strength of the plant water increased
the froth stability. Another study by Corin and Wiese,
investigated froth stability with respect to ionic strength
and frother dosage and showed that it may be possible
to interchangeably use frother dosage and solution ionic
strength to tailor the solids and water recoveries needed
from an operation [18]. McFadzean et al. also compared
the effect of frother mixtures with that of their single com-
ponent frothers on the froth stability, froth recovery and
entrainment of a platinum-bearing UG2 ore using polygly-
col and alcohol frothers [2]. The study showed that frother
mixtures resulted in a greater froth stability than either of
their component frothers. The increased froth stability was
reflected in increased froth recoveries and greater overall
valuable mineral recoveries. Farrokhpay and Zanin, dis-
cussed the synergic effect of collector and frother on froth
stability and flotation recovery where reagents (and in par-
ticular collectors and frothers) cannot be selected without
considering their synergistic effect, this concept was rarely
applied in plant practice [19]. The feed mineralogy was
also shown to have an important role in how particles and
reagents interact in flotation. The case study data suggested
that the collection and froth zone could rarely be optimised
independently of each other.
The current study investigates a frother screening
methodology using Senfroth 200 as the industry baseline,
Frother selection plays a critical part in the froth zone
characterisation during flotation. Frothers must prevent
bubble coalescence in the pulp phase, be sufficiently stable
to support the weight of the mineral, stabilise the froth and
allow drainage of water and entrained gangue minerals to
the pulp, ensure mobility and not be so stable that the froth
does not break down in the launders. Frothers can also
increase flotation kinetics.
Moyo discusses frother characterisation techniques,
which look at certain froth characteristics that play a role
in frother performance [5]. A number of methods over the
years have been developed to assess foam formation, one of
the most simple being measurement of the maximum froth
height achieved at a given superficial gas velocity [6, 7, 8, 9,
10]. Iglesias et al. modified Bikerman’s method by switching
off gas once the dynamic equilibrium height was reached
[11]. The decay of foam volume was measured with time.
This parameter was used to characterize the persistence of
the foam produced from a solution of known concentra-
tion. McLaughlin et al. used almost the same method as
Iglesias et al., however, introduced an induction time (time
elapsed between air termination and the start of froth col-
lapse) and used this as the characterizing parameter instead
[12, 11]. Their method was used on three phase froths. Xu
et al. proposed a new method of evaluating froth stability
and foamability [13]. Their adjustment of the technique
was based on their understanding that when frothers are
compared at the same concentration they will produce dif-
ferent froth heights and hence different froth stabilities. In
general, two types of tests are used, dynamic and static tests.
In a dynamic test, air is supplied continuously and foam is
allowed to grow until steady state is reached where the rate
of formation is in equilibrium with rate of decay (bubble
bursting). In static tests, the rate of foam formation is zero:
once the foam is formed, it is allowed to collapse without
further gas input or agitation.
Barbian et al. highlights the crucial role frothers play
in PGM and sulphide ore flotation recovery, where they
evaluated the effect of various frothers, with the optimal
frother-collector combination, on 4E PGM recovery by
means of laboratory batch flotation tests and a subsequent
plant trial [14]. They discussed how challenging it was to
measure froth stability quantitatively, both at laboratory
and at industrial scales. They used a quantitative dynamic
stability measure, based on the Bikerman foam test using a
non-overflowing froth column to quantify froth stability.
At laboratory scale, the froth stability measured agreed very
closely with other methods, and could be related to flota-
tion performance. The metallurgical results clearly indicated
that changes in air rate, froth depth and frother concentra-
tion result in variation in flotation performance that can be
attributed to changes in froth stability. The results showed
that high froth stability conditions occur at intermediate air
flowrates, and result in improved flotation performance. It
was found that the froth stability column is an accurate and
cost-effective method for quantifying froth stability, and for
indicating changes in flotation performance. However, the
data obtained from the ‘Bikerman’ type testwork may not
be always transferrable to the metallurgical performance
indicators as shown during the frother study described in
this paper.
Khoshdast et al. revealed that the 2D froth structure
measurement methods are associated with a considerable
bias, while 3D techniques can effectively represent the
actual froth properties [15]. It was also found that the
potential interactions between various frothers properties
and how they can influence the flotation performance in an
industrial environment are not yet understood and needs
further investigation.
Corin et al. as well as Farrokhpay and Zanin, studied
the effect of an increase in the ionic strength of plant water
on the stability of the froth [16, 17]. Their data showed that
an increase in the ionic strength of the plant water increased
the froth stability. Another study by Corin and Wiese,
investigated froth stability with respect to ionic strength
and frother dosage and showed that it may be possible
to interchangeably use frother dosage and solution ionic
strength to tailor the solids and water recoveries needed
from an operation [18]. McFadzean et al. also compared
the effect of frother mixtures with that of their single com-
ponent frothers on the froth stability, froth recovery and
entrainment of a platinum-bearing UG2 ore using polygly-
col and alcohol frothers [2]. The study showed that frother
mixtures resulted in a greater froth stability than either of
their component frothers. The increased froth stability was
reflected in increased froth recoveries and greater overall
valuable mineral recoveries. Farrokhpay and Zanin, dis-
cussed the synergic effect of collector and frother on froth
stability and flotation recovery where reagents (and in par-
ticular collectors and frothers) cannot be selected without
considering their synergistic effect, this concept was rarely
applied in plant practice [19]. The feed mineralogy was
also shown to have an important role in how particles and
reagents interact in flotation. The case study data suggested
that the collection and froth zone could rarely be optimised
independently of each other.
The current study investigates a frother screening
methodology using Senfroth 200 as the industry baseline,