XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2359
sumps feeding thickeners, and they need to use a defoamer
to ensure they can dewater slurry effectively. Another factor
dictating the amount of strong frother component tends to
be the recirculation of strong frother in the process water
compared to weaker frothers that tend to volatilize and
escape from the process, the strong frothers are carried in
the process water through the concentrate thickeners, and
find their way back into the process. A typical sign of this is
good plant performance during the trial of the new frother,
but increasing incidences of overfrothing in cleaner circuits,
sumps and thickeners a few weeks later. More importantly,
it is readily apparent from either bench scale flotation tests
of rougher tails and assay by size, or liberation data that
there are substantial losses in the coarse size fraction and
that a stronger frother is required.
Thus, there is still a need to maximize coarse particle
recovery with a use of a strong frother upfront, without
having to worry about frothing issues in the cleaners and
further downstream, or recirculation of these frothers.
NOVEL SWITCHABLE FROTHER
Recently, Syensqo has developed a novel frother technology
that enables maximizing the flotation of coarse particles in
the rougher without causing frothing issues in the cleaners,
namely the Transfoamer ™ line of frothers. This technology
relies on a pH triggered transformation in chemistry: the
product acts as a very strong frother at rougher pH range
(8–10.5). It is able to float the coarse particles, and as the
pH increases from the rougher to the cleaners stages (10.5–
11.8) it switches to a weaker frother. This product allows
for improved recoveries of coarse particles in the roughers,
while being weak in the cleaner circuits just like a weak
frother.
It enables a more aggressive and stable operating
regime in the roughers that is not possible with formulated
frothers. The switch to weak frother, once it happens, is
irreversible. The rate of switching from the strong to weak
frother is a function of pH. At pH 11.5, it can take about
30 minutes to complete the switch from strong to weak.
The product has been trialed at multiple Cu-Mo-Au opera-
tions around the globe with very promising results.
Expected Advantages
It is expected that 1st cleaners at plants will function much
more efficiently. It should help reduce the circulating load
in the cleaning circuit. Many plants, on occasion, send the
cleaner scavenger product to tailings to reduce the solids
density in the cleaners having a weak frother in the clean-
ing circuit will help avoid this situation and the resulting
metal losses. Circulating load from column back to cleaners
will also improve because of the higher concentrate grade in
cleaners. Finally, if there are issues with thickener overflow
clarity, the technology is expected to help with this, result-
ing in improved water availability. It is also expected that
plants can reduce pH and thus improve their Au recovery
when this may be operationally desirable.
Results from Pilot Plant Testing
Syensqo decided to run a continuous pilot plant at SGS
Lakefield to: a) demonstrate that the “switch” from strong
to weak was happening at practical timescales (typical
rougher-cleaner residence times), and b) the benefits in the
cleaners could be realized.
Figure 1 shows the flowsheet for the pilot plant in
which the Transfoamer ™ technology was evaluated. Ore
was ground to P80 of 200 m in a batch mill, with the con-
centrate feeding the rougher circuit consisting of 4 cells with
a residence time of about 16 minutes. The rougher concen-
trate was sent to a regrinding pin mill for it to be ground
to a size of ~30–45 microns. This reground rougher con-
centrate was sent to a conditioning tank. Lime was added
to the rougher concentrate going to the regrind mill, with
a small amount added to the conditioning tank to ensure
that the pH was as close to 11.5 as possible. The level in
the conditioning tank was the way to control the residence
time. The cleaner concentrates from each cell were collected
and sent for assay, along with cleaner tails and rougher tails.
In addition, the rougher feed and rougher concentrates
were periodically sampled. Two prototypes of the technol-
ogy were evaluated, namely the T-100 and T-200. T-200
was compared to a traditional strong frother, and T-100 to
a mixture of strong and weak frother (20/80, as is typical).
The results from the pilot plant test for T-200 are
shown in Table 1. The approach here was to compare the
T-200 to a strong frother, by pushing for the same type of
rougher circuit operation, but achieving higher concentrate
grade and reduced mass pull in the cleaning circuit.
In the rougher, it is noted that the process was run such
that the mass recoveries, concentrate grade and Cu recover-
ies were virtually the same. For the first cell in the cleaner
circuit, we see that the mass recovery has halved from 2.7%
to 1.2%, the Cu concentrate grade has doubled from 9.3
to 19.3%, a clear indicator that the froth has weakened.
We also see that the Cu recovery has dropped from 88.8%
to 82.9% this is because we did not have an opportunity
to optimize the run, i.e., a very limited operating time was
possible for each run with the planned schedule, and real
time assays were not available. If we pushed for slightly
greater mass pull (an additional 0.2%), Cu recovery would
have easily been equivalent to the strong frother. Another
sumps feeding thickeners, and they need to use a defoamer
to ensure they can dewater slurry effectively. Another factor
dictating the amount of strong frother component tends to
be the recirculation of strong frother in the process water
compared to weaker frothers that tend to volatilize and
escape from the process, the strong frothers are carried in
the process water through the concentrate thickeners, and
find their way back into the process. A typical sign of this is
good plant performance during the trial of the new frother,
but increasing incidences of overfrothing in cleaner circuits,
sumps and thickeners a few weeks later. More importantly,
it is readily apparent from either bench scale flotation tests
of rougher tails and assay by size, or liberation data that
there are substantial losses in the coarse size fraction and
that a stronger frother is required.
Thus, there is still a need to maximize coarse particle
recovery with a use of a strong frother upfront, without
having to worry about frothing issues in the cleaners and
further downstream, or recirculation of these frothers.
NOVEL SWITCHABLE FROTHER
Recently, Syensqo has developed a novel frother technology
that enables maximizing the flotation of coarse particles in
the rougher without causing frothing issues in the cleaners,
namely the Transfoamer ™ line of frothers. This technology
relies on a pH triggered transformation in chemistry: the
product acts as a very strong frother at rougher pH range
(8–10.5). It is able to float the coarse particles, and as the
pH increases from the rougher to the cleaners stages (10.5–
11.8) it switches to a weaker frother. This product allows
for improved recoveries of coarse particles in the roughers,
while being weak in the cleaner circuits just like a weak
frother.
It enables a more aggressive and stable operating
regime in the roughers that is not possible with formulated
frothers. The switch to weak frother, once it happens, is
irreversible. The rate of switching from the strong to weak
frother is a function of pH. At pH 11.5, it can take about
30 minutes to complete the switch from strong to weak.
The product has been trialed at multiple Cu-Mo-Au opera-
tions around the globe with very promising results.
Expected Advantages
It is expected that 1st cleaners at plants will function much
more efficiently. It should help reduce the circulating load
in the cleaning circuit. Many plants, on occasion, send the
cleaner scavenger product to tailings to reduce the solids
density in the cleaners having a weak frother in the clean-
ing circuit will help avoid this situation and the resulting
metal losses. Circulating load from column back to cleaners
will also improve because of the higher concentrate grade in
cleaners. Finally, if there are issues with thickener overflow
clarity, the technology is expected to help with this, result-
ing in improved water availability. It is also expected that
plants can reduce pH and thus improve their Au recovery
when this may be operationally desirable.
Results from Pilot Plant Testing
Syensqo decided to run a continuous pilot plant at SGS
Lakefield to: a) demonstrate that the “switch” from strong
to weak was happening at practical timescales (typical
rougher-cleaner residence times), and b) the benefits in the
cleaners could be realized.
Figure 1 shows the flowsheet for the pilot plant in
which the Transfoamer ™ technology was evaluated. Ore
was ground to P80 of 200 m in a batch mill, with the con-
centrate feeding the rougher circuit consisting of 4 cells with
a residence time of about 16 minutes. The rougher concen-
trate was sent to a regrinding pin mill for it to be ground
to a size of ~30–45 microns. This reground rougher con-
centrate was sent to a conditioning tank. Lime was added
to the rougher concentrate going to the regrind mill, with
a small amount added to the conditioning tank to ensure
that the pH was as close to 11.5 as possible. The level in
the conditioning tank was the way to control the residence
time. The cleaner concentrates from each cell were collected
and sent for assay, along with cleaner tails and rougher tails.
In addition, the rougher feed and rougher concentrates
were periodically sampled. Two prototypes of the technol-
ogy were evaluated, namely the T-100 and T-200. T-200
was compared to a traditional strong frother, and T-100 to
a mixture of strong and weak frother (20/80, as is typical).
The results from the pilot plant test for T-200 are
shown in Table 1. The approach here was to compare the
T-200 to a strong frother, by pushing for the same type of
rougher circuit operation, but achieving higher concentrate
grade and reduced mass pull in the cleaning circuit.
In the rougher, it is noted that the process was run such
that the mass recoveries, concentrate grade and Cu recover-
ies were virtually the same. For the first cell in the cleaner
circuit, we see that the mass recovery has halved from 2.7%
to 1.2%, the Cu concentrate grade has doubled from 9.3
to 19.3%, a clear indicator that the froth has weakened.
We also see that the Cu recovery has dropped from 88.8%
to 82.9% this is because we did not have an opportunity
to optimize the run, i.e., a very limited operating time was
possible for each run with the planned schedule, and real
time assays were not available. If we pushed for slightly
greater mass pull (an additional 0.2%), Cu recovery would
have easily been equivalent to the strong frother. Another