2785
Influence of Ultrafine Particles on the Floatability of Target
Minerals: Particle Attachment Dynamics in a Model Stirred Cell
Milad Eftekhari, Karin Schwarzenberger
Helmholtz-Zentrum Dresden-Rossendorf
Kerstin Eckert
Helmholtz-Zentrum Dresden-Rossendorf and Dresden University of Technology
ABSTRACT: Successful flotation depends on several sub-processes, often expressed as a single parameter,
floatability, which represents the efficiency of the particles to float. Floatability has been studied as a function
of various parameters, but translating these results to industrial-scale operations is complex due to different cell
hydrodynamics and designs. In this study, we use a novel approach to quantify particle floatability by studying
particle attachment to a single bubble in a model stirred cell. The method allows precise hydrodynamic control,
visualization of the attachment process, and observation of the bubble surface. In particular, we investigate the
effect of ultrafine particles on the dynamics of particles attachment and thus their floatability. The results show
that ultrafine particles can indeed significantly influence the recovery rate of target minerals in a flotation cell.
INTRODUCTION
Froth flotation is a commonly used technique for separating
valuable minerals from their ores in the mining industry.
For many decades, the emphasis of flotation was on par-
ticles of a few tens of micrometers. However, the depletion
of existing high grade ore deposits in the recent years has
shifted the current mining standards towards the exploita-
tion of lower grade mineral deposits. These low-grade ores
must be finely ground to release the finely dispersed valu-
able minerals, which can lead to various problems and chal-
lenges associated with fine/ultra-fine particles (Farrokhpay
et al. 2021). Unlike ultrafine particles, fine particles are
in the target range of flotation, and various methods have
been developed to increase their recovery, such as enhanc-
ing the collision rate by increasing the shear rate in the
flotation cell. Ultrafine particles, on the other hand, are
considered problematic because they increase the complex-
ity of the system, for example by affecting the viscosity of
the slurry (Farrokhpay et al. 2021) or (over-) stabilizing the
froth phase (Aktas et al. 2008).
Ultrafine particles have a much larger surface area per
unit mass than the coarser particles and therefore consume
a relatively higher collector dosage (Pease et al. 2006). Fully
liberated ultrafine particles can also coat the surface of valu-
able minerals, resulting in poor collector adsorption on the
surface of valuable target minerals, increasing their hydro-
philic behavior. Ultrafine particles can also lead to excessive
stabilization of the froth phase (Aktas et al. 2008), which
can be detrimental to the flotation process. This is because
if the froth is too stable, gangue particles are less likely to
be drained back into the pulp, resulting in lower grade and
selectivity of the concentrate (Farrokhpay et al. 2021). The
extent of the stability depends on the size, hydrophobicity
and shape of the particles (Barbian et al. 2005 Pugh et al.
2005). It is shown that 10 µm galena particles can extend
the froth lifetime of an alcohol aqueous solution from 17
Influence of Ultrafine Particles on the Floatability of Target
Minerals: Particle Attachment Dynamics in a Model Stirred Cell
Milad Eftekhari, Karin Schwarzenberger
Helmholtz-Zentrum Dresden-Rossendorf
Kerstin Eckert
Helmholtz-Zentrum Dresden-Rossendorf and Dresden University of Technology
ABSTRACT: Successful flotation depends on several sub-processes, often expressed as a single parameter,
floatability, which represents the efficiency of the particles to float. Floatability has been studied as a function
of various parameters, but translating these results to industrial-scale operations is complex due to different cell
hydrodynamics and designs. In this study, we use a novel approach to quantify particle floatability by studying
particle attachment to a single bubble in a model stirred cell. The method allows precise hydrodynamic control,
visualization of the attachment process, and observation of the bubble surface. In particular, we investigate the
effect of ultrafine particles on the dynamics of particles attachment and thus their floatability. The results show
that ultrafine particles can indeed significantly influence the recovery rate of target minerals in a flotation cell.
INTRODUCTION
Froth flotation is a commonly used technique for separating
valuable minerals from their ores in the mining industry.
For many decades, the emphasis of flotation was on par-
ticles of a few tens of micrometers. However, the depletion
of existing high grade ore deposits in the recent years has
shifted the current mining standards towards the exploita-
tion of lower grade mineral deposits. These low-grade ores
must be finely ground to release the finely dispersed valu-
able minerals, which can lead to various problems and chal-
lenges associated with fine/ultra-fine particles (Farrokhpay
et al. 2021). Unlike ultrafine particles, fine particles are
in the target range of flotation, and various methods have
been developed to increase their recovery, such as enhanc-
ing the collision rate by increasing the shear rate in the
flotation cell. Ultrafine particles, on the other hand, are
considered problematic because they increase the complex-
ity of the system, for example by affecting the viscosity of
the slurry (Farrokhpay et al. 2021) or (over-) stabilizing the
froth phase (Aktas et al. 2008).
Ultrafine particles have a much larger surface area per
unit mass than the coarser particles and therefore consume
a relatively higher collector dosage (Pease et al. 2006). Fully
liberated ultrafine particles can also coat the surface of valu-
able minerals, resulting in poor collector adsorption on the
surface of valuable target minerals, increasing their hydro-
philic behavior. Ultrafine particles can also lead to excessive
stabilization of the froth phase (Aktas et al. 2008), which
can be detrimental to the flotation process. This is because
if the froth is too stable, gangue particles are less likely to
be drained back into the pulp, resulting in lower grade and
selectivity of the concentrate (Farrokhpay et al. 2021). The
extent of the stability depends on the size, hydrophobicity
and shape of the particles (Barbian et al. 2005 Pugh et al.
2005). It is shown that 10 µm galena particles can extend
the froth lifetime of an alcohol aqueous solution from 17