106 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
major challenges of this process is the selection of potential
peptide candidates from libraries of several thousand avail-
able reagents. However, promising new work has developed
screening methods to effectively narrow down the list of
potential peptide candidates for selective absorption onto
target mineral species (Ku, Forbes &Brito e Abreu, 2024).
Another promising development is the use of responsive
molecules that can change the properties in response to any
stimulus such as pH, temperature and using light exposure
(Ng et al., 2018). The use of techniques such as Reversible
Addition-Fragmentation Chain Transfer (RAFT), opens up
new possibilities for polymer synthesis and the ability to
produce reagent molecules with a wider range of structures
and functions (Amini et al., 2023). These studies are in an
early exploratory stage but may pave the way for the devel-
opment of new and innovative flotation chemistries in the
future.
However, when delving deep into the complexity of
reagent chemistry, one must not lose site of the big pic-
ture. For both oxide and sulphide mineral systems, collec-
tor selectivity can be made even more challenging by the
presence of complex mineral textures, particle shape factors
and particle surface roughness and the nature of the process
water (Forbes et al., 2022 Fosu et al., 2015 Jefferson et
al., 2023 Pereira et al., 2023). This means that collector
selectivity is also dependent on outside factors such as ore
mineralogy, comminution mechanism and water sources/
water treatment strategies. Limited collector selectivity can
lead to a significant decrease in concentrate grades, mov-
ing the flotation process further away from the maximum
theoretical grade/recovery limit. It can also have a strong
impact on downstream processes. For example, an elevated
presence of pyrite in flotation concentrates treated by pyro-
metallurgy can result in significant quantities of toxic gases
(SxOy) being released into the atmosphere. For this reason,
the development of selective connector chemistries cannot
be viewed as a niche area of science, but rather it should be
viewed as an integral part of a holistic approach to mineral
processing technology development.
CHARACTERIZATION FOR DIAGNOSIS
AND OPTIMISATION
Offline Characterization
The mineralogy and liberation of an ore and its surface spe-
ciation have a significant effect on flotation performance.
To help diagnose and find solutions to overcome problems
in mineral processing flotation circuits, it is important
that methods exist to accurately characterize these particle
properties. There are some significant new techniques and
developments which are paving the way for more accurate
particle assessment.
X-ray tomography (XRT) is an emerging charac-
terization technique for measuring particle mineralogy
and liberation (Reyes et al, 2018 Miller and Lin, 2018).
Measurement is performed by passing an x-ray beam
through a sample and measuring attenuation (Figure 7).
Minerals can be identified because different elements of
different density absorb the x-rays to a different degree.
XRT has the advantage that it produces 3D images of par-
ticles which do not suffer from the stereological error asso-
ciated with the 2D measurement performed using MLA
or QEMSCAN systems. Stereological error means that the
degree of liberation measured for a particle class is biased
and can lead to wrong interpretations. It is difficult to dis-
cern, for example, whether the presence of liberated gangue
in a coarse size fraction is a consequence of natural float-
ability (which would require chemical depression to reduce
recovery) or because it has wrongly been classified as liber-
ated because of stereological error.
XRT is also a non-destructive technique which opens
the way for it to be used online down the track or in a
Figure 7. Schematic of the components of an X-Ray tomography system (after Zeiss, 2011)
major challenges of this process is the selection of potential
peptide candidates from libraries of several thousand avail-
able reagents. However, promising new work has developed
screening methods to effectively narrow down the list of
potential peptide candidates for selective absorption onto
target mineral species (Ku, Forbes &Brito e Abreu, 2024).
Another promising development is the use of responsive
molecules that can change the properties in response to any
stimulus such as pH, temperature and using light exposure
(Ng et al., 2018). The use of techniques such as Reversible
Addition-Fragmentation Chain Transfer (RAFT), opens up
new possibilities for polymer synthesis and the ability to
produce reagent molecules with a wider range of structures
and functions (Amini et al., 2023). These studies are in an
early exploratory stage but may pave the way for the devel-
opment of new and innovative flotation chemistries in the
future.
However, when delving deep into the complexity of
reagent chemistry, one must not lose site of the big pic-
ture. For both oxide and sulphide mineral systems, collec-
tor selectivity can be made even more challenging by the
presence of complex mineral textures, particle shape factors
and particle surface roughness and the nature of the process
water (Forbes et al., 2022 Fosu et al., 2015 Jefferson et
al., 2023 Pereira et al., 2023). This means that collector
selectivity is also dependent on outside factors such as ore
mineralogy, comminution mechanism and water sources/
water treatment strategies. Limited collector selectivity can
lead to a significant decrease in concentrate grades, mov-
ing the flotation process further away from the maximum
theoretical grade/recovery limit. It can also have a strong
impact on downstream processes. For example, an elevated
presence of pyrite in flotation concentrates treated by pyro-
metallurgy can result in significant quantities of toxic gases
(SxOy) being released into the atmosphere. For this reason,
the development of selective connector chemistries cannot
be viewed as a niche area of science, but rather it should be
viewed as an integral part of a holistic approach to mineral
processing technology development.
CHARACTERIZATION FOR DIAGNOSIS
AND OPTIMISATION
Offline Characterization
The mineralogy and liberation of an ore and its surface spe-
ciation have a significant effect on flotation performance.
To help diagnose and find solutions to overcome problems
in mineral processing flotation circuits, it is important
that methods exist to accurately characterize these particle
properties. There are some significant new techniques and
developments which are paving the way for more accurate
particle assessment.
X-ray tomography (XRT) is an emerging charac-
terization technique for measuring particle mineralogy
and liberation (Reyes et al, 2018 Miller and Lin, 2018).
Measurement is performed by passing an x-ray beam
through a sample and measuring attenuation (Figure 7).
Minerals can be identified because different elements of
different density absorb the x-rays to a different degree.
XRT has the advantage that it produces 3D images of par-
ticles which do not suffer from the stereological error asso-
ciated with the 2D measurement performed using MLA
or QEMSCAN systems. Stereological error means that the
degree of liberation measured for a particle class is biased
and can lead to wrong interpretations. It is difficult to dis-
cern, for example, whether the presence of liberated gangue
in a coarse size fraction is a consequence of natural float-
ability (which would require chemical depression to reduce
recovery) or because it has wrongly been classified as liber-
ated because of stereological error.
XRT is also a non-destructive technique which opens
the way for it to be used online down the track or in a
Figure 7. Schematic of the components of an X-Ray tomography system (after Zeiss, 2011)