2414 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Zn into separate concentrates. DIBDTPI was used for
this ore as the primary collector and Zn(CN)2 was used to
depress the Zn and Fe sulfides. It is noted however, that a
certain proportion of Ag in this ore is also present in sul-
fosalts not associated with any of the base metal sulfides.
When a small dosage of BCBDTC is added with DIBDTPI
during the Pb flotation stage, a significant shift in the Ag
grade-recovery curve (Figure 14). No detrimental effects on
Pb flotation nor on Zn/Fe selectivity were also observed.
Thus, it is quite clear that BCBDTC can selectively interact
with certain Ag species that even a strong, selective ligand
such as DIBDTPI cannot. This also correlates with the
voltammogram for Ag where the extent of passivation of
BCBDTC with Ag is stronger than DIBDTPI and with
the ToF-SIMS spectra which evidences the former’s ability
to form Ag complexes.
An additional strategy that was explored in this system
was bulk sulfide flotation of the final tailings, to recover any
argentiferous pyrite and other Ag values not floated prior.
PAX was used as the primary collector as well as CuSO4 to
activate pyrite. When BCBDTC is introduced in addition
to PAX and CuSO4, a significant shift in the Ag grade-
recovery curve is noticed, and the rates of Ag and S flota-
tion increase (Figure 15).
This strategy of bulk sulfide recovery is not only attrac-
tive in terms of minimizing the loss of any values, but also
for generating environmentally benign tailings by reducing
their sulfide content which is acid mine drainage generating.
PGM Ore
Bulk sulfide flotation is common practice to recover PGMs
both associated with chalcopyrite, pentlandite, and pyrrho-
tite and as individual species (PGE alloys, arsenides, tellu-
rides, sulfides, etc.). Sodium isobutyl xanthate (SIBX) and
a dithiophosphate such as di-ethyl (DEDTP) are often used
at high dosages. However, given the complex mineralogy
typical of such ores (there can be significant substitutions
in which over 350 different PGM species are possible), cer-
tain PGMs do not have the propensity to interact with xan-
thates or dithiophosphates. For this ore, when BCBDTC is
used at a low dosage on its own, PGM is recovered some-
what selectively against S (Figure 16).
Though the rates of PGM flotation are certainly stron-
ger with the SIBX/DEDTP suite, it is noteworthy that the
equilibrium recoveries of PGM for the two reagent schemes
are nearly the same, while a reduction of approximately
15% S recovery is achieved with BCBDTC. This can be
attributed to BCBDTC acting preferentially against base
metal sulfides which are “barren” (i.e., do not host any
PGMs).
When BCBDTC is added with the SIBX/DEDTP
suite, a positive shift in the PGM grade-recovery curve is
Figure 13. Au flotation with BCBDTC P80 -75 µm, pH -7.5, flotation
time -13 min
Zn into separate concentrates. DIBDTPI was used for
this ore as the primary collector and Zn(CN)2 was used to
depress the Zn and Fe sulfides. It is noted however, that a
certain proportion of Ag in this ore is also present in sul-
fosalts not associated with any of the base metal sulfides.
When a small dosage of BCBDTC is added with DIBDTPI
during the Pb flotation stage, a significant shift in the Ag
grade-recovery curve (Figure 14). No detrimental effects on
Pb flotation nor on Zn/Fe selectivity were also observed.
Thus, it is quite clear that BCBDTC can selectively interact
with certain Ag species that even a strong, selective ligand
such as DIBDTPI cannot. This also correlates with the
voltammogram for Ag where the extent of passivation of
BCBDTC with Ag is stronger than DIBDTPI and with
the ToF-SIMS spectra which evidences the former’s ability
to form Ag complexes.
An additional strategy that was explored in this system
was bulk sulfide flotation of the final tailings, to recover any
argentiferous pyrite and other Ag values not floated prior.
PAX was used as the primary collector as well as CuSO4 to
activate pyrite. When BCBDTC is introduced in addition
to PAX and CuSO4, a significant shift in the Ag grade-
recovery curve is noticed, and the rates of Ag and S flota-
tion increase (Figure 15).
This strategy of bulk sulfide recovery is not only attrac-
tive in terms of minimizing the loss of any values, but also
for generating environmentally benign tailings by reducing
their sulfide content which is acid mine drainage generating.
PGM Ore
Bulk sulfide flotation is common practice to recover PGMs
both associated with chalcopyrite, pentlandite, and pyrrho-
tite and as individual species (PGE alloys, arsenides, tellu-
rides, sulfides, etc.). Sodium isobutyl xanthate (SIBX) and
a dithiophosphate such as di-ethyl (DEDTP) are often used
at high dosages. However, given the complex mineralogy
typical of such ores (there can be significant substitutions
in which over 350 different PGM species are possible), cer-
tain PGMs do not have the propensity to interact with xan-
thates or dithiophosphates. For this ore, when BCBDTC is
used at a low dosage on its own, PGM is recovered some-
what selectively against S (Figure 16).
Though the rates of PGM flotation are certainly stron-
ger with the SIBX/DEDTP suite, it is noteworthy that the
equilibrium recoveries of PGM for the two reagent schemes
are nearly the same, while a reduction of approximately
15% S recovery is achieved with BCBDTC. This can be
attributed to BCBDTC acting preferentially against base
metal sulfides which are “barren” (i.e., do not host any
PGMs).
When BCBDTC is added with the SIBX/DEDTP
suite, a positive shift in the PGM grade-recovery curve is
Figure 13. Au flotation with BCBDTC P80 -75 µm, pH -7.5, flotation
time -13 min