3
comparing it to different frothers of different strengths
using an initial screening of the 4E PGM concentrate
grade versus recovery data with and without other reagents
in the first concentrate during a hot float. After which, a
collector dosage curve was determined using the optimum
frother selected. Once the optimum collector dosage was
determined, a plant trial was conducted over six weeks in
an On Off configuration. Froth stability tests (Bikerman)
were also conducted on a three-phase system mimicking
the conditions used during the hot float test work for com-
parative purposes.
EXPERIMENTAL
Materials
A sample of Merensky ore was used for the frother case
study. The feed grade of the ore was 4.50 g/t, 4.12 g/t and
4.19 g/t 4E (Pt, Pd, Rh, Au) for the hot float test work,
collector dosage optimization test work and plant trial,
respectively.
The frothers evaluated were Senfroth 200 – an alco-
hol and polyglycol based frother and Senfroth 153 and
Senfroth 522 were polyglycol based frothers.
Batch Flotation Test Work
The initial phase of the test work screened the frothers using
rougher feed hot floats at the operation on a Merensky ore.
The samples were taken after the primary mill and before
any reagents were added. The stream had a particle size of
45% –75 µm, and were floated with the frother only and
with other reagents plus the frother. Only the first concen-
trate, which was collected for 10 minutes, was analysed
for 4E PGM. The frothers evaluated were Senfroth 200,
Senfroth 153 and Senfroth 522 at a dosage of 20 g/t. The
other reagents comprised, SIBX at a dosage of 215 g/t,
Senkol 8 at a dosage of 53 g/t and Norilose 6064 was added
at a dosage of active content of 29 g/t.
The frother strength evaluated ranged from weak to
strong, the order was as follows Senfroth 200 was weaker
than Senfroth 153 which was weaker that Senfroth 522. It
is a common rule that the strength of the frother is assessed
by either its dynamic foamability index (DFI) or its critical
coalescence concentration (CCC). The smaller the value of
CCC the stronger the frother is. This general rule (CCC
rule) however is superficial although being well accepted
[20]. The polyglycol ether range of frothers has strong sur-
face activity, and their molecular weight (MW) and carbon
chain-length determine their strength and performance
with an increase in molecular weight (MW) resulting in
increased frothability, but lower selectivity [21, 22]. The
strength of the frothers evaluated were classified according
to their MW.
The second phase of the flotation test work determined
the optimal collector dosage for the optimal frother selected
from the initial phase of the test work. Batch flotation
test work was conducted on a 2 kg Merensky ore sample.
Flotation was carried out for 25 minutes with froth scrap-
ing every 15 seconds. The pulp level was kept constant by
adding process water when needed. Three concentrates were
collected at intervals of 0–3 minutes, 3–10 minutes and
10–25 minutes. All the concentrates and the tailings sam-
ples were filtered and dried. The dry masses were recorded,
sample preparation was completed and the samples were
submitted for 4E PGM chemical analyses. A Denver flota-
tion machine equipped with a 4.5 l cell was used during the
testwork. The impeller was run at 900 rpm and the air was
set at 7.5 L/min. Reagent dosages for the collectors dosage
curve (SIBX) was 100 g/t, 200 g/t and 300 g/t, Senkol 8
was at 53 g/t, the depressant (Norilose 6064) was added at a
dosage of active content of 29 g/t and the frother (Senfroth
153) at a dosage of 20 g/t. Error bars are based on the stan-
dard error of duplicate flotation batch tests.
Plant Trial
The plant trial was conducted over six weeks in an On Off
configuration. Reagent dosages for the collectors (SIBX)
was 215 g/t, Senkol 8 was at 53 g/t, the depressant (Norilose
6064) was added at a dosage of active content of 29 g/t and
the frother (Senfroth 153) at a dosage of 20 g/t.
Froth Stability Test Work
Froth stability tests were conducted as a screening tool for
the frothers evaluated. The test work was conducted on
frothers only and with frothers in combination with other
reagents, namely, collectors and depressants. The test work
was conducted as a three-phase system which included the
Merensky ore. The frothers evaluated were Senfroth 200,
Senfroth 153 and Senfroth 522 at a dosage of 20 g/t. The
other reagents comprised, SIBX at 215 g/t, Senkol 8 at 53
g/t and Norilose 6064 at 29 g/t. The work was conducted
in a non-overflowing column as described in McFadzean
et al. [2]. An overhead stirrer was used to keep the solids
in suspension. The tests were conducted at three different
superficial gas velocities, namely, 0.98, 1.47, and 1.96 cm/s.
Maximum equilibrium froth height was measured and
divided by the superficial gas velocity to give the froth sta-
bility value, as described by Bikerman [23]. The froth sta-
bility tests could only be conducted on a finer grind of 80%
–75 μm due to ore settling in the feed tank and blocking
comparing it to different frothers of different strengths
using an initial screening of the 4E PGM concentrate
grade versus recovery data with and without other reagents
in the first concentrate during a hot float. After which, a
collector dosage curve was determined using the optimum
frother selected. Once the optimum collector dosage was
determined, a plant trial was conducted over six weeks in
an On Off configuration. Froth stability tests (Bikerman)
were also conducted on a three-phase system mimicking
the conditions used during the hot float test work for com-
parative purposes.
EXPERIMENTAL
Materials
A sample of Merensky ore was used for the frother case
study. The feed grade of the ore was 4.50 g/t, 4.12 g/t and
4.19 g/t 4E (Pt, Pd, Rh, Au) for the hot float test work,
collector dosage optimization test work and plant trial,
respectively.
The frothers evaluated were Senfroth 200 – an alco-
hol and polyglycol based frother and Senfroth 153 and
Senfroth 522 were polyglycol based frothers.
Batch Flotation Test Work
The initial phase of the test work screened the frothers using
rougher feed hot floats at the operation on a Merensky ore.
The samples were taken after the primary mill and before
any reagents were added. The stream had a particle size of
45% –75 µm, and were floated with the frother only and
with other reagents plus the frother. Only the first concen-
trate, which was collected for 10 minutes, was analysed
for 4E PGM. The frothers evaluated were Senfroth 200,
Senfroth 153 and Senfroth 522 at a dosage of 20 g/t. The
other reagents comprised, SIBX at a dosage of 215 g/t,
Senkol 8 at a dosage of 53 g/t and Norilose 6064 was added
at a dosage of active content of 29 g/t.
The frother strength evaluated ranged from weak to
strong, the order was as follows Senfroth 200 was weaker
than Senfroth 153 which was weaker that Senfroth 522. It
is a common rule that the strength of the frother is assessed
by either its dynamic foamability index (DFI) or its critical
coalescence concentration (CCC). The smaller the value of
CCC the stronger the frother is. This general rule (CCC
rule) however is superficial although being well accepted
[20]. The polyglycol ether range of frothers has strong sur-
face activity, and their molecular weight (MW) and carbon
chain-length determine their strength and performance
with an increase in molecular weight (MW) resulting in
increased frothability, but lower selectivity [21, 22]. The
strength of the frothers evaluated were classified according
to their MW.
The second phase of the flotation test work determined
the optimal collector dosage for the optimal frother selected
from the initial phase of the test work. Batch flotation
test work was conducted on a 2 kg Merensky ore sample.
Flotation was carried out for 25 minutes with froth scrap-
ing every 15 seconds. The pulp level was kept constant by
adding process water when needed. Three concentrates were
collected at intervals of 0–3 minutes, 3–10 minutes and
10–25 minutes. All the concentrates and the tailings sam-
ples were filtered and dried. The dry masses were recorded,
sample preparation was completed and the samples were
submitted for 4E PGM chemical analyses. A Denver flota-
tion machine equipped with a 4.5 l cell was used during the
testwork. The impeller was run at 900 rpm and the air was
set at 7.5 L/min. Reagent dosages for the collectors dosage
curve (SIBX) was 100 g/t, 200 g/t and 300 g/t, Senkol 8
was at 53 g/t, the depressant (Norilose 6064) was added at a
dosage of active content of 29 g/t and the frother (Senfroth
153) at a dosage of 20 g/t. Error bars are based on the stan-
dard error of duplicate flotation batch tests.
Plant Trial
The plant trial was conducted over six weeks in an On Off
configuration. Reagent dosages for the collectors (SIBX)
was 215 g/t, Senkol 8 was at 53 g/t, the depressant (Norilose
6064) was added at a dosage of active content of 29 g/t and
the frother (Senfroth 153) at a dosage of 20 g/t.
Froth Stability Test Work
Froth stability tests were conducted as a screening tool for
the frothers evaluated. The test work was conducted on
frothers only and with frothers in combination with other
reagents, namely, collectors and depressants. The test work
was conducted as a three-phase system which included the
Merensky ore. The frothers evaluated were Senfroth 200,
Senfroth 153 and Senfroth 522 at a dosage of 20 g/t. The
other reagents comprised, SIBX at 215 g/t, Senkol 8 at 53
g/t and Norilose 6064 at 29 g/t. The work was conducted
in a non-overflowing column as described in McFadzean
et al. [2]. An overhead stirrer was used to keep the solids
in suspension. The tests were conducted at three different
superficial gas velocities, namely, 0.98, 1.47, and 1.96 cm/s.
Maximum equilibrium froth height was measured and
divided by the superficial gas velocity to give the froth sta-
bility value, as described by Bikerman [23]. The froth sta-
bility tests could only be conducted on a finer grind of 80%
–75 μm due to ore settling in the feed tank and blocking