XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2339
poor pentlandite flotation performance for stainless steel
milled NK ore.
Flotation Performance Based On
The milling media have significant influences on the flota-
tion performance of both two ores, but there is a striking
difference between JC and NK ore. For JC ore, stainless
steel milling obtained remarkable higher Cu and Ni grade,
slightly higher Cu and Ni recovery, significantly lower solid
and water recovery and slower Ni flotation. In the initial
stage of flotation for stainless steel milled JC ore, the floated
minerals are mainly Cu sulphides, presenting a remarkable
copper color, while relatively less amounts of nickel min-
erals and gangue minerals are floated. After milled with
cast iron balls, a large amount of serpentine floats up at
the beginning of flotation, and the final solid recovery is
significantly higher. While for NK ore, stainless steel mill-
ing obtained higher Cu grade but much lower Ni grade,
significantly lower Cu and Ni recovery, also lower solid and
water recovery.
The differences in flotation kinetics are mainly caused
by the galvanic effect on the mineral surface, while iron
contamination produced during cast iron milling process
are the main factors contributing to the differences in flo-
tation behavior of gangue minerals. Cast iron balls have
strong reducibility, and its rest potentials is lower than sul-
fide minerals in ores. During the milling process, cast iron
balls always acts as an anode in the galvanic couple, whereas
sulfide minerals with high rest potential act as cathodes.
Within the galvanic interaction, electrons transfer from the
anode to the cathode, resulting in oxidation of cast iron
balls, while the surface oxidation and metal ions dissolu-
tion on sulphide minerals surface is hindered. The flow
of electrons from the grinding media to sulphide miner-
als increases the oxidation of grinding media, leading to
more oxidized iron species in the slurry and on the surface
of sulphide minerals, namely Fe(OH)3, FeOOH, Fe2O3,
and Fe3O4 (Azizi et al., 2013). At the same time, a cer-
tain amount of iron in the form of ions is produced in the
slurry. The iron oxides have a certain depression effect on
sulfide minerals (Huang and Grano, 2005 Bruckard et al.,
2011), which is consistent with the trend of flotation recov-
ery after milled JC ores with two media.
During the stainless steel milling process, chalcopyrite
with lowest rest potential serves as anode in the galvanic
couple, the oxidation and dissolution of which is acceler-
ated with electrons flowing from chalcopyrite to pentland-
ite and pyrrhotite, while pentlandite and pyrrhotite act as
cathode, on which oxygen is preferentially reduced (Azizi
et al., 2013). Meanwhile, the copper ions dissolved from
chalcopyrite due to the galvanic oxidation will result in the
activation of pentlandite and pyrrhotite, which is incon-
sistent with the flotation performance of higher Po and Pn
flotation recovery for both JC and NK ore milled with cast
iron balls.
It has been widely recognized that the milling environ-
ment has a large effect on the flotation of sulphide minerals
(Peng and Grano, 2010). The difference of flotation per-
formance for the two ores after milled with different milled
media is speculated to be mainly attributed to mineral
composition difference of two ores. The gangue minerals
of NK ore are mainly pyroxene, talc, and chromite, with
the high content of strong hydrophobic mineral—talc up
to 7%. The main gangue minerals of JC copper nickel ore
are serpentine, with a content up to 34%. The minerals that
have a significant effect on the flotation process of copper
nickel minerals are talc and serpentine. There are significant
differences in the surface properties and flotation behav-
ior of talc and serpentine under the action of two milled
media, which in turn have a significant effect on the flota-
tion performance of sulfide copper nickel ores.
The Fe species generated during the milling process of
JC ore with cast iron balls enhance the attachment of ser-
pentine on sulphide minerals surface, which contribute to
much more serpentine introduced to the flotation concen-
trate. But in the case of NK ore, the flotation performance
is a completely different situation due to the naturally
hydrophobic mineral, talc. When milled with stainless steel
balls, the surface properties of talc remain strong hydropho-
bicity, and a certain proportion of the frother are adsorbed
by talc, resulting in a significant decrease in the flotation
amount of sulphide minerals. The Fe species produced dur-
ing cast iron milling covers on the surface to some extent
reduce the strong hydrophobicity of talc and the adsorp-
tion and consumption capacity of frothers and collectors
(Seng and Finch, 2010). Therefore, it can increase the flota-
tion amount of sulfide minerals in ores with high talc con-
tent, while increasing the entrainment effect on chromite,
resulting in a significant increase of concentrate mass, but a
decrease in talc and gangue proportion in the concentrate.
It is supposed that strong hydrophobicity and adsorption
capacity on frothers and collectors of talc result in a much
lower copper nickel recovery of NK ore after stainless steel
balls milled compared to cast iron balls milled. Further
investigation is necessary to verify the influence of mineral
component on the flotation performance under different
milling conditions.
poor pentlandite flotation performance for stainless steel
milled NK ore.
Flotation Performance Based On
The milling media have significant influences on the flota-
tion performance of both two ores, but there is a striking
difference between JC and NK ore. For JC ore, stainless
steel milling obtained remarkable higher Cu and Ni grade,
slightly higher Cu and Ni recovery, significantly lower solid
and water recovery and slower Ni flotation. In the initial
stage of flotation for stainless steel milled JC ore, the floated
minerals are mainly Cu sulphides, presenting a remarkable
copper color, while relatively less amounts of nickel min-
erals and gangue minerals are floated. After milled with
cast iron balls, a large amount of serpentine floats up at
the beginning of flotation, and the final solid recovery is
significantly higher. While for NK ore, stainless steel mill-
ing obtained higher Cu grade but much lower Ni grade,
significantly lower Cu and Ni recovery, also lower solid and
water recovery.
The differences in flotation kinetics are mainly caused
by the galvanic effect on the mineral surface, while iron
contamination produced during cast iron milling process
are the main factors contributing to the differences in flo-
tation behavior of gangue minerals. Cast iron balls have
strong reducibility, and its rest potentials is lower than sul-
fide minerals in ores. During the milling process, cast iron
balls always acts as an anode in the galvanic couple, whereas
sulfide minerals with high rest potential act as cathodes.
Within the galvanic interaction, electrons transfer from the
anode to the cathode, resulting in oxidation of cast iron
balls, while the surface oxidation and metal ions dissolu-
tion on sulphide minerals surface is hindered. The flow
of electrons from the grinding media to sulphide miner-
als increases the oxidation of grinding media, leading to
more oxidized iron species in the slurry and on the surface
of sulphide minerals, namely Fe(OH)3, FeOOH, Fe2O3,
and Fe3O4 (Azizi et al., 2013). At the same time, a cer-
tain amount of iron in the form of ions is produced in the
slurry. The iron oxides have a certain depression effect on
sulfide minerals (Huang and Grano, 2005 Bruckard et al.,
2011), which is consistent with the trend of flotation recov-
ery after milled JC ores with two media.
During the stainless steel milling process, chalcopyrite
with lowest rest potential serves as anode in the galvanic
couple, the oxidation and dissolution of which is acceler-
ated with electrons flowing from chalcopyrite to pentland-
ite and pyrrhotite, while pentlandite and pyrrhotite act as
cathode, on which oxygen is preferentially reduced (Azizi
et al., 2013). Meanwhile, the copper ions dissolved from
chalcopyrite due to the galvanic oxidation will result in the
activation of pentlandite and pyrrhotite, which is incon-
sistent with the flotation performance of higher Po and Pn
flotation recovery for both JC and NK ore milled with cast
iron balls.
It has been widely recognized that the milling environ-
ment has a large effect on the flotation of sulphide minerals
(Peng and Grano, 2010). The difference of flotation per-
formance for the two ores after milled with different milled
media is speculated to be mainly attributed to mineral
composition difference of two ores. The gangue minerals
of NK ore are mainly pyroxene, talc, and chromite, with
the high content of strong hydrophobic mineral—talc up
to 7%. The main gangue minerals of JC copper nickel ore
are serpentine, with a content up to 34%. The minerals that
have a significant effect on the flotation process of copper
nickel minerals are talc and serpentine. There are significant
differences in the surface properties and flotation behav-
ior of talc and serpentine under the action of two milled
media, which in turn have a significant effect on the flota-
tion performance of sulfide copper nickel ores.
The Fe species generated during the milling process of
JC ore with cast iron balls enhance the attachment of ser-
pentine on sulphide minerals surface, which contribute to
much more serpentine introduced to the flotation concen-
trate. But in the case of NK ore, the flotation performance
is a completely different situation due to the naturally
hydrophobic mineral, talc. When milled with stainless steel
balls, the surface properties of talc remain strong hydropho-
bicity, and a certain proportion of the frother are adsorbed
by talc, resulting in a significant decrease in the flotation
amount of sulphide minerals. The Fe species produced dur-
ing cast iron milling covers on the surface to some extent
reduce the strong hydrophobicity of talc and the adsorp-
tion and consumption capacity of frothers and collectors
(Seng and Finch, 2010). Therefore, it can increase the flota-
tion amount of sulfide minerals in ores with high talc con-
tent, while increasing the entrainment effect on chromite,
resulting in a significant increase of concentrate mass, but a
decrease in talc and gangue proportion in the concentrate.
It is supposed that strong hydrophobicity and adsorption
capacity on frothers and collectors of talc result in a much
lower copper nickel recovery of NK ore after stainless steel
balls milled compared to cast iron balls milled. Further
investigation is necessary to verify the influence of mineral
component on the flotation performance under different
milling conditions.