2226 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
recovered by steam stripping, condensed, and recycled in
Phase IV. The hydrophobic particles exiting this step are
recovered as concentrate substantially free of hydrophilic
waste particles and surface moisture.
EXPERIMENTAL AND RESULTS
Copper Concentration
A CST sample assaying 0.265%Cu was received from a
porphyry copper ore flotation plant. An SEM analysis of
the sample showed that much of the unrecovered copper
was in the –20 µm fraction. Nevertheless, 99% of the
copper-bearing minerals (chalcopyrite) exhibited 30%
surface liberation. Furthermore, some of them may have
been superficially oxidized during the course of long
retention times associated with recirculation. Therefore,
the CST sample was wet ground in a laboratory ball mill
to d80 =14 µm before subjecting the mill product to a
single-stage laboratory flotation test. The test was con-
ducted using 0.3 kg/t potassium amyl xanthate (KAX)
and 0.041 kg/t potassium octyl hydroxamate (KOHX) at
pH 11.5 as adjusted with lime. The result obtained after a
4-minute flotation time are presented in Table 2. The cop-
per recovery was high (82.1%) but the concentrate grade
was low (1.03%Cu).
The flotation product was then subjected to a TLF test
to obtain 30.36%Cu concentrate at a 79% copper recov-
ery. These results clearly demonstrate the effectiveness of
the TLF process for the recovery of ultrafine minerals with
d80 =14 µm, which can be attributed to the high contact
angles and elimination of entrainment.
In another TLF test, a copper concentrate assaying
34.7%Cu was obtained at a 75.8% recovery. The high
degree of selectivity observed was most probably due to the
removal of the entrained particles in the Morganizer (Step
III, Figure 2). The use of CaO as a pyrite depressant also
helped increase the product grade.
Ultra-Clean Coal Production
Table 2 shows the bench-scale TLF test results obtained
with Eastern Kentucky bituminous coal. The coal sample
was taken from the third-stage flotation concentrate stream
in an operating coal preparation plant. The as-received
sample assayed 4.97% ash content and the particle size
was d80 =11.2 μm. As shown, a single-stage TLF process
reduced the ash content to 2.30% with an organic recovery
of 99%. In the presence of a dispersant (Reagent A), the
ash content was further reduced to 2.04%. It is likely that
the dispersing agent increased hydrophilicity of the ash-
forming minerals, which in turn increased the differences
in surface properties between coal and mineral matter. It
Figure 2. Steps in TLF process: I) collection of hydrophobic
particles by oil drops in water, II) formation of o/w
emulsion, III) formation of w/o emulsion by phase inversion
and demulsification by vibrating screens in a Morganizer,
IV) recovery and recycling of spent oil
Table 1. Recovery of copper from a CST by flotation, followed by TLF
Process Products
Weight (%)Grade
(%Cu)
Cu Recovery (%)
Flotation TLF Flotation TLF
TLF Conc. — 2.7 30.36 — 79.0
Tail — 97.3 0.22 — 21.0
Feed — 100.0 1.03 — 100.0
Flotation Conc. 21.1 — 1.03 82.1 —
Tail 78.9 — 0.06 17.9 —
Feed 100.0 — 0.265 100.0 —
recovered by steam stripping, condensed, and recycled in
Phase IV. The hydrophobic particles exiting this step are
recovered as concentrate substantially free of hydrophilic
waste particles and surface moisture.
EXPERIMENTAL AND RESULTS
Copper Concentration
A CST sample assaying 0.265%Cu was received from a
porphyry copper ore flotation plant. An SEM analysis of
the sample showed that much of the unrecovered copper
was in the –20 µm fraction. Nevertheless, 99% of the
copper-bearing minerals (chalcopyrite) exhibited 30%
surface liberation. Furthermore, some of them may have
been superficially oxidized during the course of long
retention times associated with recirculation. Therefore,
the CST sample was wet ground in a laboratory ball mill
to d80 =14 µm before subjecting the mill product to a
single-stage laboratory flotation test. The test was con-
ducted using 0.3 kg/t potassium amyl xanthate (KAX)
and 0.041 kg/t potassium octyl hydroxamate (KOHX) at
pH 11.5 as adjusted with lime. The result obtained after a
4-minute flotation time are presented in Table 2. The cop-
per recovery was high (82.1%) but the concentrate grade
was low (1.03%Cu).
The flotation product was then subjected to a TLF test
to obtain 30.36%Cu concentrate at a 79% copper recov-
ery. These results clearly demonstrate the effectiveness of
the TLF process for the recovery of ultrafine minerals with
d80 =14 µm, which can be attributed to the high contact
angles and elimination of entrainment.
In another TLF test, a copper concentrate assaying
34.7%Cu was obtained at a 75.8% recovery. The high
degree of selectivity observed was most probably due to the
removal of the entrained particles in the Morganizer (Step
III, Figure 2). The use of CaO as a pyrite depressant also
helped increase the product grade.
Ultra-Clean Coal Production
Table 2 shows the bench-scale TLF test results obtained
with Eastern Kentucky bituminous coal. The coal sample
was taken from the third-stage flotation concentrate stream
in an operating coal preparation plant. The as-received
sample assayed 4.97% ash content and the particle size
was d80 =11.2 μm. As shown, a single-stage TLF process
reduced the ash content to 2.30% with an organic recovery
of 99%. In the presence of a dispersant (Reagent A), the
ash content was further reduced to 2.04%. It is likely that
the dispersing agent increased hydrophilicity of the ash-
forming minerals, which in turn increased the differences
in surface properties between coal and mineral matter. It
Figure 2. Steps in TLF process: I) collection of hydrophobic
particles by oil drops in water, II) formation of o/w
emulsion, III) formation of w/o emulsion by phase inversion
and demulsification by vibrating screens in a Morganizer,
IV) recovery and recycling of spent oil
Table 1. Recovery of copper from a CST by flotation, followed by TLF
Process Products
Weight (%)Grade
(%Cu)
Cu Recovery (%)
Flotation TLF Flotation TLF
TLF Conc. — 2.7 30.36 — 79.0
Tail — 97.3 0.22 — 21.0
Feed — 100.0 1.03 — 100.0
Flotation Conc. 21.1 — 1.03 82.1 —
Tail 78.9 — 0.06 17.9 —
Feed 100.0 — 0.265 100.0 —