3052 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Other Collectors
Orfom ® CO Collectors are collectors with a good potential
to maximize the recovery of gold/silver-bearing minerals as
well as mixed copper sulfide minerals while simultaneously
eliminating gangue minerals like pyrite. Results in Figure 9
were obtained on chalcopyrite and molybdenite for one of
these collectors, CO 100, which is n-dodecyl mercaptan.
Results in the absence and presence of Orfom ® D8 show
the same results as obtained for ethyl xanthate although
the pH range of 8-11 is not as wide (compare Figure 6).
Because the collector has an organic tail that contains 12
carbons, these results do not necessarily concur with the
proposed mechanism that suggested xanthate collector
be no longer than 4 carbons if it were vertically oriented.
However, it is known that mercaptans are not as strong of
collectors as xanthates and it could be that the adsorption
density of the CO 100 was low. This would still allow the
Orfom ® D8 to mask its hydrophobicity. It is important to
note that, even under these conditions, molybdenite was
still not impacted.
CONCLUSIONS
The FT-IR and zeta potential results gathered in this
research verifies the mechanism of Orfom ® D8 as a Cu
depressant for Cu-Mo flotation. FT-IR spectra showed
Orfom ® D8 and KEX both chemisorbed on chalcopyrite
but did not interact with molybdenite. Chemisorption
to chalcopyrite occurred through the trithiocarbonate
-120
-100
-80
-60
-40
-20
0
20
40
2 4 6 8 10 12
pH
FeS2
FeS2 +D8
Figure 7. Electrophoretic Mobility of Pyrite with and without Orfom® D8
-200
-150
-100
-50
0
50
100
2 4 6 8 10 12
pH
PbS
PbS +D8
Figure 8. Electrophoretic Mobility of Galena with/without Orfom® D8
Electrophorec
Mobility/mV
ElectrophoretiMob
ilit/mV
y

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Extracted Text (may have errors)

3052 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Other Collectors
Orfom ® CO Collectors are collectors with a good potential
to maximize the recovery of gold/silver-bearing minerals as
well as mixed copper sulfide minerals while simultaneously
eliminating gangue minerals like pyrite. Results in Figure 9
were obtained on chalcopyrite and molybdenite for one of
these collectors, CO 100, which is n-dodecyl mercaptan.
Results in the absence and presence of Orfom ® D8 show
the same results as obtained for ethyl xanthate although
the pH range of 8-11 is not as wide (compare Figure 6).
Because the collector has an organic tail that contains 12
carbons, these results do not necessarily concur with the
proposed mechanism that suggested xanthate collector
be no longer than 4 carbons if it were vertically oriented.
However, it is known that mercaptans are not as strong of
collectors as xanthates and it could be that the adsorption
density of the CO 100 was low. This would still allow the
Orfom ® D8 to mask its hydrophobicity. It is important to
note that, even under these conditions, molybdenite was
still not impacted.
CONCLUSIONS
The FT-IR and zeta potential results gathered in this
research verifies the mechanism of Orfom ® D8 as a Cu
depressant for Cu-Mo flotation. FT-IR spectra showed
Orfom ® D8 and KEX both chemisorbed on chalcopyrite
but did not interact with molybdenite. Chemisorption
to chalcopyrite occurred through the trithiocarbonate
-120
-100
-80
-60
-40
-20
0
20
40
2 4 6 8 10 12
pH
FeS2
FeS2 +D8
Figure 7. Electrophoretic Mobility of Pyrite with and without Orfom® D8
-200
-150
-100
-50
0
50
100
2 4 6 8 10 12
pH
PbS
PbS +D8
Figure 8. Electrophoretic Mobility of Galena with/without Orfom® D8
Electrophorec
Mobility/mV
ElectrophoretiMob
ilit/mV
y

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XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3053
(SCS2–) functionality as revealed in FT-IR results, while
the carboxylate (CO2–) functionality protruded into solu-
tion due to the highly negative potential existing on the
functional group, hence making chalcopyrite hydrophilic
thereby causing its depression even though ethyl xanthate
was still present as a co-adsorbed species. Although the
two molecules are the same length, the hydrophilic forces
from Orfom ® D8 dominate because they reach further into
solution than the hydrophobic forces from ethyl xanthate.
Measured differently from previously results, zeta potential
studies with Orfom ® D8 also confirm that chalcopyrite
possesses a negatively charged surface between pH 7.5-10.5
but is maximum near pH 8.5-9.5 which agrees with flota-
tion tests conducted in previous studies. Pyrite and galena
interaction with Orfom ® D8 mimic that of chalcopyrite
indicating that Orfom ® D8 can also cause their depression.
When the collector was changed to n-dodecyl mercaptan
(Orfom CO 100), the same behavior of Orfom ® D8 on
chalcopyrite was observed. This was not anticipated but
results were explained because mercaptans are weaker col-
lectors and may have adsorbed at low density in a horizon-
tal orientation.
ACKNOWLEDGMENTS
Sincere appreciation is extended to Montana Technological
University and its Metallurgical &Materials Engineering
Department for their support of this research. Many thanks
are offered to Freeport McMoRan, Rio Tinto and Capstone
Copper for their coordinated funding and sponsorship.
Special gratitude is extended to David Miller of Chevron
Phillips Chemical who helped with the coordination we
hope he has a wonderful retirement.
REFERENCES
[1] Bagci, E., Ekmekci, Z. and Bradshaw, D., 2007.
Adsorption behaviour of xanthate and dithiophosph-
inate from their mixtures on chalcopyrite. Minerals
Engineering, 20(10), pp.1047–1053.
[2] Bai, L., Liu, J., Han, Y., Jiang, K. and Zhao, W., 2018.
Effects of xanthate on flotation kinetics of chalcopy-
rite and talc. Minerals, 8(9), p.369.
[3] Bozer, K.A., 2022. Synthesis and Stabilization of
Gold Nanoparticles from Chloride and Cyanide
Systems (Doctoral dissertation, Montana Tech of The
University of Montana).
[4] Bresson, C.R., Parlman, R.M. and Robles, B.R.,
Phillips Petroleum Co, 1984. Polycarboxylic acid
derivatives and uses. U.S. Patent 4,482,480.
[5] Burke, A., Yilmaz, E., Hasirci, N.E.S.R.İ.N. and
Yilmaz, O., 2002. Iron (III) ion removal from solu-
tion through adsorption on chitosan. Journal of
Applied Polymer Science, 84(6), pp.1185–1192.
[6] Chen, J.H., Lan, L.H. and Liao, X.J., 2013.
Depression effect of pseudo glycolythiourea
acid in flotation separation of copper–molybde-
num. Transactions of Nonferrous Metals Society of
China, 23(3), pp.824–831.
-110.00
-90.00
-70.00
-50.00
-30.00
-10.00
10.00
30.00
pH
CuFeS2 +CO 100
CuFeS2 +CO 100 +D8
MoS2 +CO 100
MoS2 +CO 100 +D8
Figure 9. Electrophoretic Mobility of Chalcopyrite and Molybdenite with CO 100
collector and Orfom® D8
Zeta
Potenti
(mV)

Previous Page Next Page

Extracted Text (may have errors)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3053
(SCS2–) functionality as revealed in FT-IR results, while
the carboxylate (CO2–) functionality protruded into solu-
tion due to the highly negative potential existing on the
functional group, hence making chalcopyrite hydrophilic
thereby causing its depression even though ethyl xanthate
was still present as a co-adsorbed species. Although the
two molecules are the same length, the hydrophilic forces
from Orfom ® D8 dominate because they reach further into
solution than the hydrophobic forces from ethyl xanthate.
Measured differently from previously results, zeta potential
studies with Orfom ® D8 also confirm that chalcopyrite
possesses a negatively charged surface between pH 7.5-10.5
but is maximum near pH 8.5-9.5 which agrees with flota-
tion tests conducted in previous studies. Pyrite and galena
interaction with Orfom ® D8 mimic that of chalcopyrite
indicating that Orfom ® D8 can also cause their depression.
When the collector was changed to n-dodecyl mercaptan
(Orfom CO 100), the same behavior of Orfom ® D8 on
chalcopyrite was observed. This was not anticipated but
results were explained because mercaptans are weaker col-
lectors and may have adsorbed at low density in a horizon-
tal orientation.
ACKNOWLEDGMENTS
Sincere appreciation is extended to Montana Technological
University and its Metallurgical &Materials Engineering
Department for their support of this research. Many thanks
are offered to Freeport McMoRan, Rio Tinto and Capstone
Copper for their coordinated funding and sponsorship.
Special gratitude is extended to David Miller of Chevron
Phillips Chemical who helped with the coordination we
hope he has a wonderful retirement.
REFERENCES
[1] Bagci, E., Ekmekci, Z. and Bradshaw, D., 2007.
Adsorption behaviour of xanthate and dithiophosph-
inate from their mixtures on chalcopyrite. Minerals
Engineering, 20(10), pp.1047–1053.
[2] Bai, L., Liu, J., Han, Y., Jiang, K. and Zhao, W., 2018.
Effects of xanthate on flotation kinetics of chalcopy-
rite and talc. Minerals, 8(9), p.369.
[3] Bozer, K.A., 2022. Synthesis and Stabilization of
Gold Nanoparticles from Chloride and Cyanide
Systems (Doctoral dissertation, Montana Tech of The
University of Montana).
[4] Bresson, C.R., Parlman, R.M. and Robles, B.R.,
Phillips Petroleum Co, 1984. Polycarboxylic acid
derivatives and uses. U.S. Patent 4,482,480.
[5] Burke, A., Yilmaz, E., Hasirci, N.E.S.R.İ.N. and
Yilmaz, O., 2002. Iron (III) ion removal from solu-
tion through adsorption on chitosan. Journal of
Applied Polymer Science, 84(6), pp.1185–1192.
[6] Chen, J.H., Lan, L.H. and Liao, X.J., 2013.
Depression effect of pseudo glycolythiourea
acid in flotation separation of copper–molybde-
num. Transactions of Nonferrous Metals Society of
China, 23(3), pp.824–831.
-110.00
-90.00
-70.00
-50.00
-30.00
-10.00
10.00
30.00
pH
CuFeS2 +CO 100
CuFeS2 +CO 100 +D8
MoS2 +CO 100
MoS2 +CO 100 +D8
Figure 9. Electrophoretic Mobility of Chalcopyrite and Molybdenite with CO 100
collector and Orfom® D8
Zeta
Potenti
(mV)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3051
negative surface charge at all of the pH conditions investi-
gated, i.e., pH 2-12. These results do not change when the
molybdenite is treated with Orfom ® D8 as shown in green.
In this regard, Orfom ® D8 has no impact on molybdenite.
Clearly, Orfom ® D8 has a significant impact on chal-
copyrite but no bearing on molybdenite. The different
behavior between the two mineral surfaces clearly shows
specificity for chalcopyrite explaining why it is selectively
depressed and molybdenite continues to float. More impor-
tantly, these results were determined with the Malvern
Zetasizer Nano ZS, but duplicate profiles obtained by
Young and Timbillah [17–20] who used a Microtrac Stabino,
an instrument that measures zeta potential via a streaming
potential technique. Again, the mechanism is verified.
Preliminary Studies – Other Minerals and Collectors
Aside from chalcopyrite and molybdenite, Cu-Mo ores
normally contain other sulfide minerals. These ores ubiqui-
tously include pyrite but could also include galena, sphal-
erite and a host of distinctive sulfides. Knowing how these
minerals behave in the absence and presence of Orfom ®
D8 can be important after all, their presence can cause
contamination of the Cu and Mo concentrates let alone
create potential environmental problems and other mining
sustainability issues. Furthermore, results could open new
markets for using the depressant. Lastly, as noted previ-
ously, the Orfom ® D8 adsorption mechanism was derived
from studies involving ethyl xanthate. Its behavior with
other collectors needs to be explored.
Pyrite
According to Young and Timbillah [17–20], the pros-
pect of Orfom ® D8 being used for pyrite depression was
raised based on interaction or binding energy studies (see
Figure 2b). These theoretical calculations confirm the
electrophoretic mobility results shown in Figure 7. In the
absence of Orfom ® D8, pyrite exhibits a slight negative
potential at most pH values. Charge reversal is observed
between pH 7.5-9.5. When the pyrite is treated with
Orfom ® D8, the pyrite becomes more negative between
~pH 6.5-11 and particularly between pH 7-10. The pH
range is wider than observed for chalcopyrite, indicat-
ing pyrite and chalcopyrite depression will occur simul-
taneously. Young and Timbillah [17–20] used XRD and
SEM/MLA and saw increased pyrite in the chalcopyrite
concentrate.
Galena
Electrophoretic mobility results for galena are shown in
Figure 8. As shown in yellow, galena exhibits a slightly
negative zeta potential across the whole pH range but with-
out charge reversal. However, when galena is treated with
Orfom ® D8, it yields negative zeta potentials from pH
6-11.5 as shown in green. Assessing Orfom ® D8 interac-
tion shows that the pH range decreases from galena pyrite
chalcopyrite. Clearly, Orfom ® D8 would depress galena
under the same conditions used in Cu-Mo separation. If
galena were present in Cu-Mo bulk sulfide concentrate, it
would report to the Cu concentrate.
-160
-140
-120
-100
-80
-60
-40
-20
0
20
2 4 6 8 10 12
pH
CuFeS2 +D8
CuFeS2
Mo
Mo +D8
Figure 6. Electrophoretic Mobility of Chalcopyrite and Molybdenite with/without
Orfom® D8 Depressant
Zeta
potential
/mV

Previous Page Next Page

Extracted Text (may have errors)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3051
negative surface charge at all of the pH conditions investi-
gated, i.e., pH 2-12. These results do not change when the
molybdenite is treated with Orfom ® D8 as shown in green.
In this regard, Orfom ® D8 has no impact on molybdenite.
Clearly, Orfom ® D8 has a significant impact on chal-
copyrite but no bearing on molybdenite. The different
behavior between the two mineral surfaces clearly shows
specificity for chalcopyrite explaining why it is selectively
depressed and molybdenite continues to float. More impor-
tantly, these results were determined with the Malvern
Zetasizer Nano ZS, but duplicate profiles obtained by
Young and Timbillah [17–20] who used a Microtrac Stabino,
an instrument that measures zeta potential via a streaming
potential technique. Again, the mechanism is verified.
Preliminary Studies – Other Minerals and Collectors
Aside from chalcopyrite and molybdenite, Cu-Mo ores
normally contain other sulfide minerals. These ores ubiqui-
tously include pyrite but could also include galena, sphal-
erite and a host of distinctive sulfides. Knowing how these
minerals behave in the absence and presence of Orfom ®
D8 can be important after all, their presence can cause
contamination of the Cu and Mo concentrates let alone
create potential environmental problems and other mining
sustainability issues. Furthermore, results could open new
markets for using the depressant. Lastly, as noted previ-
ously, the Orfom ® D8 adsorption mechanism was derived
from studies involving ethyl xanthate. Its behavior with
other collectors needs to be explored.
Pyrite
According to Young and Timbillah [17–20], the pros-
pect of Orfom ® D8 being used for pyrite depression was
raised based on interaction or binding energy studies (see
Figure 2b). These theoretical calculations confirm the
electrophoretic mobility results shown in Figure 7. In the
absence of Orfom ® D8, pyrite exhibits a slight negative
potential at most pH values. Charge reversal is observed
between pH 7.5-9.5. When the pyrite is treated with
Orfom ® D8, the pyrite becomes more negative between
~pH 6.5-11 and particularly between pH 7-10. The pH
range is wider than observed for chalcopyrite, indicat-
ing pyrite and chalcopyrite depression will occur simul-
taneously. Young and Timbillah [17–20] used XRD and
SEM/MLA and saw increased pyrite in the chalcopyrite
concentrate.
Galena
Electrophoretic mobility results for galena are shown in
Figure 8. As shown in yellow, galena exhibits a slightly
negative zeta potential across the whole pH range but with-
out charge reversal. However, when galena is treated with
Orfom ® D8, it yields negative zeta potentials from pH
6-11.5 as shown in green. Assessing Orfom ® D8 interac-
tion shows that the pH range decreases from galena pyrite
chalcopyrite. Clearly, Orfom ® D8 would depress galena
under the same conditions used in Cu-Mo separation. If
galena were present in Cu-Mo bulk sulfide concentrate, it
would report to the Cu concentrate.
-160
-140
-120
-100
-80
-60
-40
-20
0
20
2 4 6 8 10 12
pH
CuFeS2 +D8
CuFeS2
Mo
Mo +D8
Figure 6. Electrophoretic Mobility of Chalcopyrite and Molybdenite with/without
Orfom® D8 Depressant
Zeta
potential
/mV