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Impact of Low pH Pit Water Containing Various Ion Species on
Copper Sulfide Flotation at Chino Mine
Fahimeh Dehghani, Corrina Beaven, Thien Vethosodsakda
Freeport-McMoRan-Chino Mine
ABSTRACT: The surface chemistry of sulfide ores plays a substantial role in flotation performance. Chino
Mine, New Mexico, is going to mine ore underneath a pit water level containing dissolved compounds and
ions of almost all types with a low pH around 1.8. The water will change the surface chemistry of the ore.
Consequently, the processing of this ore would be challenging. In this study, the impact of pit water was
investigated on copper sulfide flotation by conducting bench-scale flotation. In the first step, some control tests
were done on clean ore to check its flotation performance. Then, a series of flotation tests were designed and
conducted based on various contacting times between ore and pit water, diverse types, and dosage of chemicals,
pH, and solid%. Finally, the tests results were analyzed to identify any negative impact of pit water on the
kinetics, grade, and recovery of the flotation.
Keywords: Copper minerals flotation, Surface chemistry, Chemical reagents
INTRODUCTION
Due to ongoing global economic development, there is a
significant need for both copper production and consump-
tion. By 2035, global copper demand will roughly double
from the 25 million metric tons (MMt) today to nearly 50
MMt (S&P Global, 2022). Therefore, exploration, extrac-
tion, and processing of the potential copper sources would
be necessary to cover market needs. In Chino Mine, 26
million tons of copper minerals with 0.64% Cu were cov-
ered by 500 million gallons of pit water with a low pH. So,
it is valuable to extract and process the ore. But pit water
contains various types of ions and compounds. The impacts
of those compounds should be considered on flotation
performance.
The accumulation of varied species can have positive
and negative effects on the minerals’ surface chemistry and
flotation performance. Unwanted minerals can be activated
by alkali metal ions such as Ca2+. The presence of Ca2+ can
also depress pyrite in copper flotation. Sulfate and thiosul-
fate can increase froth stability and decrease the grade of
the concentrate (Biçak et al., 2012 Forssberg and Hallin,
1989 Johnson, 2003 Levay and Schumann, 2006 Rao
and Finch, 1989).
Hydrolyse ions such as NaCl and KCl are attributed
to their high ionic strength. However, hydrolysable ions
such as magnesium, calcium, carbonate, etc. participate by
increasing pH. Additionally, secondary ions such as Mg2+,
CO32-, SO42–, etc. may play a significant role in surface
phenomena, including bubble coalescence and froth layer
thickness growth (Laskowski and Castro, 2008 2012).
The most important chemical aspect to be considered in
flotation systems is the precipitation of ions at an alkaline
pH. Lime addition forms Mg(OH)2, calcium carbon-
ate (CaCO3), and other insoluble Ca salts. Precipitates
formed at pH 10 are detrimental to the flotation process,
Impact of Low pH Pit Water Containing Various Ion Species on
Copper Sulfide Flotation at Chino Mine
Fahimeh Dehghani, Corrina Beaven, Thien Vethosodsakda
Freeport-McMoRan-Chino Mine
ABSTRACT: The surface chemistry of sulfide ores plays a substantial role in flotation performance. Chino
Mine, New Mexico, is going to mine ore underneath a pit water level containing dissolved compounds and
ions of almost all types with a low pH around 1.8. The water will change the surface chemistry of the ore.
Consequently, the processing of this ore would be challenging. In this study, the impact of pit water was
investigated on copper sulfide flotation by conducting bench-scale flotation. In the first step, some control tests
were done on clean ore to check its flotation performance. Then, a series of flotation tests were designed and
conducted based on various contacting times between ore and pit water, diverse types, and dosage of chemicals,
pH, and solid%. Finally, the tests results were analyzed to identify any negative impact of pit water on the
kinetics, grade, and recovery of the flotation.
Keywords: Copper minerals flotation, Surface chemistry, Chemical reagents
INTRODUCTION
Due to ongoing global economic development, there is a
significant need for both copper production and consump-
tion. By 2035, global copper demand will roughly double
from the 25 million metric tons (MMt) today to nearly 50
MMt (S&P Global, 2022). Therefore, exploration, extrac-
tion, and processing of the potential copper sources would
be necessary to cover market needs. In Chino Mine, 26
million tons of copper minerals with 0.64% Cu were cov-
ered by 500 million gallons of pit water with a low pH. So,
it is valuable to extract and process the ore. But pit water
contains various types of ions and compounds. The impacts
of those compounds should be considered on flotation
performance.
The accumulation of varied species can have positive
and negative effects on the minerals’ surface chemistry and
flotation performance. Unwanted minerals can be activated
by alkali metal ions such as Ca2+. The presence of Ca2+ can
also depress pyrite in copper flotation. Sulfate and thiosul-
fate can increase froth stability and decrease the grade of
the concentrate (Biçak et al., 2012 Forssberg and Hallin,
1989 Johnson, 2003 Levay and Schumann, 2006 Rao
and Finch, 1989).
Hydrolyse ions such as NaCl and KCl are attributed
to their high ionic strength. However, hydrolysable ions
such as magnesium, calcium, carbonate, etc. participate by
increasing pH. Additionally, secondary ions such as Mg2+,
CO32-, SO42–, etc. may play a significant role in surface
phenomena, including bubble coalescence and froth layer
thickness growth (Laskowski and Castro, 2008 2012).
The most important chemical aspect to be considered in
flotation systems is the precipitation of ions at an alkaline
pH. Lime addition forms Mg(OH)2, calcium carbon-
ate (CaCO3), and other insoluble Ca salts. Precipitates
formed at pH 10 are detrimental to the flotation process,