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Improving Flotation Using Super Collectors
Mohit Gupta, Kaiwu Huang, Roe-Hoan Yoon
Center for Advanced Separation Technologies, Virginia Tech, Blacksburg, VA
ABSTRACT: In flotation, air bubbles selectively collect hydrophobic particles, leaving hydrophilic particles
behind. Various hydrophobizing agents (collectors) are used to increase the water contact angles (q) of target
minerals, typically to 60–80°. In the present work, we developed novel collectors that can increase q 150°.
Based on laboratory flotation test results and liberation data, the impacts of using the new reagents, tentatively
called Super Collectors, have been determined using a flotation model that can predict both grade and recovery.
The results show that the new reagents can greatly increase throughput without losing copper recoveries. The
reagents are also useful for coarse particle flotation.
INTRODUCTION
In 1905, Sulman and Picard were awarded a U.S. patent
for using air bubbles to selectively collect hydrophobic par-
ticles from the aqueous phase, leaving hydrophilic particles
behind (US Patent 793,808). Since then, flotation has been
used to produce practically all metals humans use, includ-
ing copper.
Flotation is a surface-based separation process that
works efficiently for a relatively narrow particle over the
20 and 150 µm range (Wills and Finch, 2016). With
steadily declining ore grades with time, it becomes neces-
sary to grind mined ores to finer sizes for mineral liberation,
which entails significant increases in energy consumption.
To address this issue, the mineral processing industry has
developed a strong interest in increasing the upper particle
size limit well above the upper particle size limit of 150 µm.
There are two ways to improve coarse particle flotation.
One is to reduce the turbulence in a flotation cell, and the
other is to increase the attractive force for bubble-particle
attachment to minimize the probability of bubble-particle
detachment. The attachment force should decrease with
increasing particle size as the contact area decreases with
increasing particle size and decreasing surface liberation.
At Escondida, mineral liberation drops dramatically above
150 µm, causing difficulties in floating particles above this
size due to the small area of surface exposure for copper-
bearing minerals (Clark et al., 2005).
Flotation commences with bubble-particle attachment
which requires a mineral surface to be selectively hydropho-
bized for bubble-particle attachment. Particle hydropho-
bicity is measured most commonly by contact angles (θ)
which vary with the interfacial tensions at the solid/liquid
(gSL), solid/vapor (gSV), and liquid/vapor (gLV) interfaces.
These surface tensions can be controlled such that the wet-
ting tension (gLV–gSL) becomes less than gLV to rupture the
wetting film and form a three-phase contact line with finite
contact angle. The authors of the present investigation
developed a novel method of rendering mineral surfaces
hydrophobic with θ 150°, and named the proprietary
reagents tentatively “Super Collectors (SCs).” There are
more than one reagent compositions that can render most
of the minerals hydrophobic with the q in the range of 115
to 170°. In general, hydrophobic surfaces with q 150° are
referred to as superhydrophobic.
It was the objective of the present investigation to
compare the performance of the super collectors with a
Improving Flotation Using Super Collectors
Mohit Gupta, Kaiwu Huang, Roe-Hoan Yoon
Center for Advanced Separation Technologies, Virginia Tech, Blacksburg, VA
ABSTRACT: In flotation, air bubbles selectively collect hydrophobic particles, leaving hydrophilic particles
behind. Various hydrophobizing agents (collectors) are used to increase the water contact angles (q) of target
minerals, typically to 60–80°. In the present work, we developed novel collectors that can increase q 150°.
Based on laboratory flotation test results and liberation data, the impacts of using the new reagents, tentatively
called Super Collectors, have been determined using a flotation model that can predict both grade and recovery.
The results show that the new reagents can greatly increase throughput without losing copper recoveries. The
reagents are also useful for coarse particle flotation.
INTRODUCTION
In 1905, Sulman and Picard were awarded a U.S. patent
for using air bubbles to selectively collect hydrophobic par-
ticles from the aqueous phase, leaving hydrophilic particles
behind (US Patent 793,808). Since then, flotation has been
used to produce practically all metals humans use, includ-
ing copper.
Flotation is a surface-based separation process that
works efficiently for a relatively narrow particle over the
20 and 150 µm range (Wills and Finch, 2016). With
steadily declining ore grades with time, it becomes neces-
sary to grind mined ores to finer sizes for mineral liberation,
which entails significant increases in energy consumption.
To address this issue, the mineral processing industry has
developed a strong interest in increasing the upper particle
size limit well above the upper particle size limit of 150 µm.
There are two ways to improve coarse particle flotation.
One is to reduce the turbulence in a flotation cell, and the
other is to increase the attractive force for bubble-particle
attachment to minimize the probability of bubble-particle
detachment. The attachment force should decrease with
increasing particle size as the contact area decreases with
increasing particle size and decreasing surface liberation.
At Escondida, mineral liberation drops dramatically above
150 µm, causing difficulties in floating particles above this
size due to the small area of surface exposure for copper-
bearing minerals (Clark et al., 2005).
Flotation commences with bubble-particle attachment
which requires a mineral surface to be selectively hydropho-
bized for bubble-particle attachment. Particle hydropho-
bicity is measured most commonly by contact angles (θ)
which vary with the interfacial tensions at the solid/liquid
(gSL), solid/vapor (gSV), and liquid/vapor (gLV) interfaces.
These surface tensions can be controlled such that the wet-
ting tension (gLV–gSL) becomes less than gLV to rupture the
wetting film and form a three-phase contact line with finite
contact angle. The authors of the present investigation
developed a novel method of rendering mineral surfaces
hydrophobic with θ 150°, and named the proprietary
reagents tentatively “Super Collectors (SCs).” There are
more than one reagent compositions that can render most
of the minerals hydrophobic with the q in the range of 115
to 170°. In general, hydrophobic surfaces with q 150° are
referred to as superhydrophobic.
It was the objective of the present investigation to
compare the performance of the super collectors with a