2458 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Effect of Grinding Mill Type
The effect of grinding mill type on the recovery of miller-
ite and pentlandite from the nickel sulphide sample with
ethyl xanthate at the air-set potential and pH 9 is shown
in Figure 6. There appears to be little difference between
steel and stainless steel with almost all the millerite being
recovered after 8 minutes of flotation and between 70 and
75% of the pentlandite after grinding in either media. The
slight differences between the two tests may be due to slight
differences in feed distribution.
Effect of Collector Type
The other collectors (apart for xanthate) chosen for testing
were a thionocarbamate, Cytec 3894, and a dithiophos-
phate, Cytec Aero 3501. As both were commercial grade
and an accurate molecular weight was unknown, the same
collector dose as in the xanthate tests (100 g/t) was used for
all collector types. The recovery of millerite and pentland-
ite from the nickel sulphide-quartz mixture at the air-set
potential and pH 9 after grinding in a steel mill and using
three collector types is shown in Figure 7. After 8 minutes,
millerite was almost completely recovered with all three col-
lector types but the recovery of pentlandite varied between
60 and 75%. For the dosage used, xanthate recovered the
most pentlandite and the thionocarbamate the least.
Figure 8 shows the effect of pulp potential on the
recovery of millerite and pentlandite at pH 9 using the
three different collectors. Xanthate floats millerite strongly
between 0 and +650 mV SHE and the dithiophosphate
collector also floated millerite very strongly from –100 to
+600 mV SHE. In contrast, the thionocarbamate collector
floated millerite strongly at the air-set potential and above
but flotability was reduced below the air-set potential. With
a dithiophosphate collector, there did not appear to be any
region where a separation between the two minerals could
be achieved. The recovery of pentlandite was similar across
the pulp potential range tested. However, with the thiono-
carbamate collector, a separation between the two minerals
was possible at high potential and with better selectivity
relative to xanthate.
CONCLUSIONS
This study has demonstrated that millerite can be separated
from pentlandite via froth flotation using pulp potential
(Eh) control. The key findings were:
• The separation can be made at high potentials using
xanthate or thionocarbamate as collector, but no sep-
aration was achieved using dithiophosphate
• The region of separation is different to that pre-
dicted from single mineral tests presumably due to
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9
Flotation Time (min)
Steel mill, Millerite
Steel mill, Pentlandite
S.Steel mill, Millerite
S.Steel mill, Pentlandite
Figure 6. Recovery-time data comparing the effect of grinding mill type on the recovery of millerite and
pentlandite at the air set potential at pH 9 with 100 g/t KeX
Percent
recovery
of
mine
ra(%)
l
Effect of Grinding Mill Type
The effect of grinding mill type on the recovery of miller-
ite and pentlandite from the nickel sulphide sample with
ethyl xanthate at the air-set potential and pH 9 is shown
in Figure 6. There appears to be little difference between
steel and stainless steel with almost all the millerite being
recovered after 8 minutes of flotation and between 70 and
75% of the pentlandite after grinding in either media. The
slight differences between the two tests may be due to slight
differences in feed distribution.
Effect of Collector Type
The other collectors (apart for xanthate) chosen for testing
were a thionocarbamate, Cytec 3894, and a dithiophos-
phate, Cytec Aero 3501. As both were commercial grade
and an accurate molecular weight was unknown, the same
collector dose as in the xanthate tests (100 g/t) was used for
all collector types. The recovery of millerite and pentland-
ite from the nickel sulphide-quartz mixture at the air-set
potential and pH 9 after grinding in a steel mill and using
three collector types is shown in Figure 7. After 8 minutes,
millerite was almost completely recovered with all three col-
lector types but the recovery of pentlandite varied between
60 and 75%. For the dosage used, xanthate recovered the
most pentlandite and the thionocarbamate the least.
Figure 8 shows the effect of pulp potential on the
recovery of millerite and pentlandite at pH 9 using the
three different collectors. Xanthate floats millerite strongly
between 0 and +650 mV SHE and the dithiophosphate
collector also floated millerite very strongly from –100 to
+600 mV SHE. In contrast, the thionocarbamate collector
floated millerite strongly at the air-set potential and above
but flotability was reduced below the air-set potential. With
a dithiophosphate collector, there did not appear to be any
region where a separation between the two minerals could
be achieved. The recovery of pentlandite was similar across
the pulp potential range tested. However, with the thiono-
carbamate collector, a separation between the two minerals
was possible at high potential and with better selectivity
relative to xanthate.
CONCLUSIONS
This study has demonstrated that millerite can be separated
from pentlandite via froth flotation using pulp potential
(Eh) control. The key findings were:
• The separation can be made at high potentials using
xanthate or thionocarbamate as collector, but no sep-
aration was achieved using dithiophosphate
• The region of separation is different to that pre-
dicted from single mineral tests presumably due to
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9
Flotation Time (min)
Steel mill, Millerite
Steel mill, Pentlandite
S.Steel mill, Millerite
S.Steel mill, Pentlandite
Figure 6. Recovery-time data comparing the effect of grinding mill type on the recovery of millerite and
pentlandite at the air set potential at pH 9 with 100 g/t KeX
Percent
recovery
of
mine
ra(%)
l