XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2353
(+75µm) size classes. Sample masses, solids concentration
(%m/m), sizing, and assay data are then mass balanced by
minimising the weighted sum of squared errors. Errors are
reported at 90% confidence intervals.
RESULTS AND DISCUSSION
Overall Copper Recovery
The copper recovery as a function of time is shown in
Figure 2 for the different dosing methods at the high (5g/t)
and low (1g/t) dosing levels. Additionally, tests were per-
formed without collector to determine the ore’s degree of
natural floatability.
The results show that for the high dosage level, which
could be described as a ‘near overdosing’ level, all dosing
methods achieve a similar (~93%) final copper recovery,
but the initial recovery for the batch method is signifi-
cantly higher than for the aero- and zero methods. This
is not unexpected when one considers how the collector
concentration for the different methods varies over time.
Adsorption density is a function of solution concentration.
The batch method tests begin with collector concentration
at a maximum, and so will also begin with maximum col-
lector adsorption density on the mineral surface Therefore,
the batch method tests should demonstrate higher initial
recoveries than the other dosing methods, which begin
with collector concentration at 0 ppm.
For the no collector and low dosage tests, which could
be described as ‘starvation’ level, the batch method pro-
duced a similar shaped curve with marginally higher (~2%)
recoveries than the no collector test. Compared with the no
collector test, the final recovery of the aero- and zero meth-
ods are higher (~9.5 and 5.5% respectively). It is worth not-
ing that for the aero- and zero methods, the initial recoveries
are consistently lower than the no collector test. This result
supports the observation made while performing the tests
that it took several minutes to form a stable and persis-
tent froth bed for the aero- and zero method tests at both
the high and low dosage levels. The reason for this froth
response when there is only a minute collector concentra-
tion in the flotation system is yet to be determined.
Figure 3 shows the copper grade-recovery relation-
ships for the different dosing methods at high (5g/t) and
low (1g/t) collector dosing levels. The batch method and
no collector test curves fall within a narrow recovery range,
and for the low/no collector levels, have a steep grade curve.
These features would make manipulating the system to
consistently achieve a target grade difficult. The zero- and
aero tests fall approximately on the same curve for all meth-
ods and dosage levels, with the high dosage levels moving
rightwards along the curve to achieve more recovery at the
cost of grade.
Copper Recovery by Size
The copper recovery for the fine (–38µm), middling
(–38µm to +75µm) and coarse (+75µm) size fractions are
given in Table 1 for the different dosing methods at the low
and high collector dosage level.
For the high level (near overdosing), the recovery for
the fine fraction is the same for all dosing methods. Thus,
it appears that at the high collector dosing level, there is
sufficient collector in the system to make close to all of
the particles amenable to flotation hydrophobic enough to
be recovered, regardless of the dosing method employed.
Figure 4 shows that the distribution of copper in the con-
centrate is uniform for the different dosing levels for the
high level of collector dosing. It also shows that significantly
more copper is distributed in the coarser size fractions for
the high collector dosing level than for the low dosage level.
For the low dosage level (starvation), we begin to see
recovery differences for the different dosing methods. The
Air
Collector
Air
Collector
Air
Collector
Nebulizer
A B C
Figure 1. Schematic showing the apparatus used to deliver collector and the delivery point for the Batch (A), Aero (B) and
Zero (C) dosing methods
(+75µm) size classes. Sample masses, solids concentration
(%m/m), sizing, and assay data are then mass balanced by
minimising the weighted sum of squared errors. Errors are
reported at 90% confidence intervals.
RESULTS AND DISCUSSION
Overall Copper Recovery
The copper recovery as a function of time is shown in
Figure 2 for the different dosing methods at the high (5g/t)
and low (1g/t) dosing levels. Additionally, tests were per-
formed without collector to determine the ore’s degree of
natural floatability.
The results show that for the high dosage level, which
could be described as a ‘near overdosing’ level, all dosing
methods achieve a similar (~93%) final copper recovery,
but the initial recovery for the batch method is signifi-
cantly higher than for the aero- and zero methods. This
is not unexpected when one considers how the collector
concentration for the different methods varies over time.
Adsorption density is a function of solution concentration.
The batch method tests begin with collector concentration
at a maximum, and so will also begin with maximum col-
lector adsorption density on the mineral surface Therefore,
the batch method tests should demonstrate higher initial
recoveries than the other dosing methods, which begin
with collector concentration at 0 ppm.
For the no collector and low dosage tests, which could
be described as ‘starvation’ level, the batch method pro-
duced a similar shaped curve with marginally higher (~2%)
recoveries than the no collector test. Compared with the no
collector test, the final recovery of the aero- and zero meth-
ods are higher (~9.5 and 5.5% respectively). It is worth not-
ing that for the aero- and zero methods, the initial recoveries
are consistently lower than the no collector test. This result
supports the observation made while performing the tests
that it took several minutes to form a stable and persis-
tent froth bed for the aero- and zero method tests at both
the high and low dosage levels. The reason for this froth
response when there is only a minute collector concentra-
tion in the flotation system is yet to be determined.
Figure 3 shows the copper grade-recovery relation-
ships for the different dosing methods at high (5g/t) and
low (1g/t) collector dosing levels. The batch method and
no collector test curves fall within a narrow recovery range,
and for the low/no collector levels, have a steep grade curve.
These features would make manipulating the system to
consistently achieve a target grade difficult. The zero- and
aero tests fall approximately on the same curve for all meth-
ods and dosage levels, with the high dosage levels moving
rightwards along the curve to achieve more recovery at the
cost of grade.
Copper Recovery by Size
The copper recovery for the fine (–38µm), middling
(–38µm to +75µm) and coarse (+75µm) size fractions are
given in Table 1 for the different dosing methods at the low
and high collector dosage level.
For the high level (near overdosing), the recovery for
the fine fraction is the same for all dosing methods. Thus,
it appears that at the high collector dosing level, there is
sufficient collector in the system to make close to all of
the particles amenable to flotation hydrophobic enough to
be recovered, regardless of the dosing method employed.
Figure 4 shows that the distribution of copper in the con-
centrate is uniform for the different dosing levels for the
high level of collector dosing. It also shows that significantly
more copper is distributed in the coarser size fractions for
the high collector dosing level than for the low dosage level.
For the low dosage level (starvation), we begin to see
recovery differences for the different dosing methods. The
Air
Collector
Air
Collector
Air
Collector
Nebulizer
A B C
Figure 1. Schematic showing the apparatus used to deliver collector and the delivery point for the Batch (A), Aero (B) and
Zero (C) dosing methods