2450
Use of Controlled Pulp Potential for the Separation of Millerite
from Pentlandite by Froth Flotation
Leanne K. Smith, Mark I. Pownceby, Warren J. Bruckard
CSIRO Mineral Resources
Nebeal Faris, Miao Chen
CSIRO Mineral Resources
School of Science, RMIT University
ABSTRACT: The use of controlled pulp potential (Eh) during froth flotation to separate two nickel sulfide
minerals, millerite (NiS) and pentlandite (Fe4.5Ni4.5S8), and thereby produce separate millerite and pentlandite
products was investigated. Batch single mineral flotation tests were performed on a high-quality nickel sulfide
specimen from Canada, grading 55.2% Ni and containing 47.4% pentlandite and 51.9% millerite. Potassium
ethyl xanthate, a commercial grade thionocarbamate, and a commercial grade dithiophosphate were used as the
collectors and flotation was performed at pH 9. The pulp potential was varied between –100 and +750 mV vs
SHE by using sodium hypochlorite save for at +350 mV, which was the air-set potential. No selective separation
of millerite over pentlandite was achieved using the dithiophosphate collector across the pulp potential range
studied. Selective separation of millerite over pentlandite took place above the air-set potential with xanthate
with the best result obtained at +650 mV vs SHE, where the cumulative recovery of millerite to the flotation
concentrate was 97% and pentlandite 24%. Selective separation of millerite over pentlandite at +650 mV vs
SHE was also accomplished with the thionocarbamate collector, the selectivity being better relative to xanthate
with only 14% of the pentlandite reporting to the millerite concentrate. Use of this approach could theoretically
enable the recovery of separate high- and low-grade nickel concentrates from nickel sulfide ores containing both
millerite and pentlandite.
INTRODUCTION
Since the establishment of the electrochemical aspects of
sulfide mineral flotation numerous investigations into the
effects of pulp potential (Eh) control in flotation of sulfide
minerals have been pursued (Cheng and Iwasaki, 1992
Ralston, 1991 Ruonal et al., 1997 Woods, 2003). CSIRO
Mineral Resources has also investigated the effect of pulp
potential on the flotation a range of sulfide minerals from
single mineral batch flotation tests performed on high-
grade natural minerals diluted in quartz (Heyes and Trahar,
1977, 1979 Guy and Trahar, 1984, 1985 Trahar, 1984
Senior et al., 1994, 2006, 2009 Smith et al., 2011, 2012).
For example, the data has been used to identify flotation
conditions where pulp potential and pH effects might be
exploited to separate arsenic-rich minerals from other cop-
per minerals (Bruckard et al., 2010 Smith and Bruckard,
2007 Smith et al., 2012) and arsenic-rich minerals from
other nickel sulfides (Smith et al., 2009).
A summary of research to date by Shean and Cilliers
(2011) and Woods (2003) suggests that very little published
research has been carried out on the application of Eh control
during the differential flotation of individual nickel sulfide
Use of Controlled Pulp Potential for the Separation of Millerite
from Pentlandite by Froth Flotation
Leanne K. Smith, Mark I. Pownceby, Warren J. Bruckard
CSIRO Mineral Resources
Nebeal Faris, Miao Chen
CSIRO Mineral Resources
School of Science, RMIT University
ABSTRACT: The use of controlled pulp potential (Eh) during froth flotation to separate two nickel sulfide
minerals, millerite (NiS) and pentlandite (Fe4.5Ni4.5S8), and thereby produce separate millerite and pentlandite
products was investigated. Batch single mineral flotation tests were performed on a high-quality nickel sulfide
specimen from Canada, grading 55.2% Ni and containing 47.4% pentlandite and 51.9% millerite. Potassium
ethyl xanthate, a commercial grade thionocarbamate, and a commercial grade dithiophosphate were used as the
collectors and flotation was performed at pH 9. The pulp potential was varied between –100 and +750 mV vs
SHE by using sodium hypochlorite save for at +350 mV, which was the air-set potential. No selective separation
of millerite over pentlandite was achieved using the dithiophosphate collector across the pulp potential range
studied. Selective separation of millerite over pentlandite took place above the air-set potential with xanthate
with the best result obtained at +650 mV vs SHE, where the cumulative recovery of millerite to the flotation
concentrate was 97% and pentlandite 24%. Selective separation of millerite over pentlandite at +650 mV vs
SHE was also accomplished with the thionocarbamate collector, the selectivity being better relative to xanthate
with only 14% of the pentlandite reporting to the millerite concentrate. Use of this approach could theoretically
enable the recovery of separate high- and low-grade nickel concentrates from nickel sulfide ores containing both
millerite and pentlandite.
INTRODUCTION
Since the establishment of the electrochemical aspects of
sulfide mineral flotation numerous investigations into the
effects of pulp potential (Eh) control in flotation of sulfide
minerals have been pursued (Cheng and Iwasaki, 1992
Ralston, 1991 Ruonal et al., 1997 Woods, 2003). CSIRO
Mineral Resources has also investigated the effect of pulp
potential on the flotation a range of sulfide minerals from
single mineral batch flotation tests performed on high-
grade natural minerals diluted in quartz (Heyes and Trahar,
1977, 1979 Guy and Trahar, 1984, 1985 Trahar, 1984
Senior et al., 1994, 2006, 2009 Smith et al., 2011, 2012).
For example, the data has been used to identify flotation
conditions where pulp potential and pH effects might be
exploited to separate arsenic-rich minerals from other cop-
per minerals (Bruckard et al., 2010 Smith and Bruckard,
2007 Smith et al., 2012) and arsenic-rich minerals from
other nickel sulfides (Smith et al., 2009).
A summary of research to date by Shean and Cilliers
(2011) and Woods (2003) suggests that very little published
research has been carried out on the application of Eh control
during the differential flotation of individual nickel sulfide