XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 655
CONCLUDING SUMMARY
The low alkaline flotation process (FLOT-ART) has been
developed to replace cyanide and lime conventionally used
for depressing pyrite in various copper and copper-gold
operations. The key feature of FLOT-ART is that it is envi-
ronmentally friendly and has no significant detrimental
effect on flotation performance when poor quality water
such as brackish or high salinity water is used. Moreover,
the flotation performance and process economics of this
process are better than that for conventional high lime and
cyanide-based schemes even for some complex copper ores
with a high pyrite to copper ratio. The literature review
clearly points out the potential of this low-alkaline process
but an in-depth understanding of the principles is critical
for its successful use.
Figure 3 demonstrates that the problems with high
lime addition to depress pyrite in copper or copper-gold
flotation. High lime addition often requires a higher dosage
of collector and/or a stronger non-selective collector (eg.
xanthate) to maintain higher copper recoveries. A stronger
collector inadvertently activates some liberated as well as
locked pyrite associated with copper minerals. This in turn
necessitates further increase in lime addition to depress the
activated pyrite, which slows down the flotation kinetics
of copper minerals. To compensate, a higher dosage of col-
lector becomes necessary to ensure the copper recovery is
not compromised. This becomes a vicious cycle leading to
a high alkaline flotation system with compromised selectiv-
ity. This can become even more problematic with the use of
non-conventional water sources like brackish or seawater,
eventually leading to poor recovery and concentrate quality
(Gorain et al., 2013, 2016). In our experience, a high alka-
line flotation with non-selective reagent chemistry leads to
sub-optimal copper flotation performance.
Gorain et al (2016) have demonstrated for very com-
plex copper ores (with high pyrite content) that selective
copper flotation is possible using a low alkaline flotation
system. FLOT-ART’s application of advanced electrochem-
istry in the flotation of some copper and copper-gold ores
using non-conventional water sources like seawater has
demonstrated that effective depression of pyrite is possible
using a low alkaline flotation system (pH8.5). This dispels
the myth that pyrite depression for copper ores is only pos-
sible at high pH flotation conditions (pH10.5) in cleaner
flotation. A low alkaline flotation process for copper-gold
ores also improves the recovery of gold and molybdenite.
Figure 3. Illustration of a viscous cycle involving a high alkaline flotation system using non-
selective or mixed collector system
CONCLUDING SUMMARY
The low alkaline flotation process (FLOT-ART) has been
developed to replace cyanide and lime conventionally used
for depressing pyrite in various copper and copper-gold
operations. The key feature of FLOT-ART is that it is envi-
ronmentally friendly and has no significant detrimental
effect on flotation performance when poor quality water
such as brackish or high salinity water is used. Moreover,
the flotation performance and process economics of this
process are better than that for conventional high lime and
cyanide-based schemes even for some complex copper ores
with a high pyrite to copper ratio. The literature review
clearly points out the potential of this low-alkaline process
but an in-depth understanding of the principles is critical
for its successful use.
Figure 3 demonstrates that the problems with high
lime addition to depress pyrite in copper or copper-gold
flotation. High lime addition often requires a higher dosage
of collector and/or a stronger non-selective collector (eg.
xanthate) to maintain higher copper recoveries. A stronger
collector inadvertently activates some liberated as well as
locked pyrite associated with copper minerals. This in turn
necessitates further increase in lime addition to depress the
activated pyrite, which slows down the flotation kinetics
of copper minerals. To compensate, a higher dosage of col-
lector becomes necessary to ensure the copper recovery is
not compromised. This becomes a vicious cycle leading to
a high alkaline flotation system with compromised selectiv-
ity. This can become even more problematic with the use of
non-conventional water sources like brackish or seawater,
eventually leading to poor recovery and concentrate quality
(Gorain et al., 2013, 2016). In our experience, a high alka-
line flotation with non-selective reagent chemistry leads to
sub-optimal copper flotation performance.
Gorain et al (2016) have demonstrated for very com-
plex copper ores (with high pyrite content) that selective
copper flotation is possible using a low alkaline flotation
system. FLOT-ART’s application of advanced electrochem-
istry in the flotation of some copper and copper-gold ores
using non-conventional water sources like seawater has
demonstrated that effective depression of pyrite is possible
using a low alkaline flotation system (pH8.5). This dispels
the myth that pyrite depression for copper ores is only pos-
sible at high pH flotation conditions (pH10.5) in cleaner
flotation. A low alkaline flotation process for copper-gold
ores also improves the recovery of gold and molybdenite.
Figure 3. Illustration of a viscous cycle involving a high alkaline flotation system using non-
selective or mixed collector system