XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2697
for the same position, the signal for a higher tip speed is
lower. However, when the force signals are averaged over
each vertical distance for a certain tip speed, a clear propor-
tional trend is seen as that in Figure 3 (b). Although TKE
can be estimated from power readings of the cell, this is an
estimated global value and cannot be used for the spatial
distribution of turbulence in a flotation cell.
CONCLUSIONS AND OUTLOOK
To better quantify the turbulent kinetic energy (TKE) in
multiphase flows, an improved piezosensor technique was
proposed. By means of this piezosensor it was demonstrated
that turbulence can be inferred from the pressure differ-
ence at the sensor boundary layer, and further insights were
gained when compared to previous literature. For instance,
it was shown that across different radial and axial positions,
the forces calculated were statistically significantly different
from each other, especially in the case between the region
near the rotor-stator and the rest of the cell. Moreover, an
initial correlation was established between the calculated
forces from the sensor and TKE obtained both experimen-
tally (PIV) and empirically, which have not been performed
previously. It is worth noting that the main assumptions for
the empirical correlations using the power draw method are
local equilibrium between turbulence production and dis-
sipation and local isotropy of small scales.
It was further shown that the need to understand the
local changes in turbulence in a flotation cell is clear, how-
ever, optical techniques such as PIV or LDA, are limited
in applicability due to opaque 3-phase slurries and rough
operating conditions in industrial flotation cells. The piezo-
electric sensor technique offers adaptability as no special
conditions are required. It is portable and requires a few
inexpensive devices to output reasonable results.
• Due to the complex nature of turbulence, it is aimed
to improve on these first results by considering the
following:
• PIV experiments in dilute two-phase (1% gas frac-
tion) flows to study the effect of the sensor film on
the local flow pattern with bubbles (as opposed to
single-phase (liquid) only)
• Compare the force signals with numerical results
• Improve signal stability by using more advanced
measurement devices with higher sensitivity
Figure 6. PVS Force measurements in two-phase with varying superficial gas velocities and tip speeds, at radial position: (a)
9cm (b) 15cm
for the same position, the signal for a higher tip speed is
lower. However, when the force signals are averaged over
each vertical distance for a certain tip speed, a clear propor-
tional trend is seen as that in Figure 3 (b). Although TKE
can be estimated from power readings of the cell, this is an
estimated global value and cannot be used for the spatial
distribution of turbulence in a flotation cell.
CONCLUSIONS AND OUTLOOK
To better quantify the turbulent kinetic energy (TKE) in
multiphase flows, an improved piezosensor technique was
proposed. By means of this piezosensor it was demonstrated
that turbulence can be inferred from the pressure differ-
ence at the sensor boundary layer, and further insights were
gained when compared to previous literature. For instance,
it was shown that across different radial and axial positions,
the forces calculated were statistically significantly different
from each other, especially in the case between the region
near the rotor-stator and the rest of the cell. Moreover, an
initial correlation was established between the calculated
forces from the sensor and TKE obtained both experimen-
tally (PIV) and empirically, which have not been performed
previously. It is worth noting that the main assumptions for
the empirical correlations using the power draw method are
local equilibrium between turbulence production and dis-
sipation and local isotropy of small scales.
It was further shown that the need to understand the
local changes in turbulence in a flotation cell is clear, how-
ever, optical techniques such as PIV or LDA, are limited
in applicability due to opaque 3-phase slurries and rough
operating conditions in industrial flotation cells. The piezo-
electric sensor technique offers adaptability as no special
conditions are required. It is portable and requires a few
inexpensive devices to output reasonable results.
• Due to the complex nature of turbulence, it is aimed
to improve on these first results by considering the
following:
• PIV experiments in dilute two-phase (1% gas frac-
tion) flows to study the effect of the sensor film on
the local flow pattern with bubbles (as opposed to
single-phase (liquid) only)
• Compare the force signals with numerical results
• Improve signal stability by using more advanced
measurement devices with higher sensitivity
Figure 6. PVS Force measurements in two-phase with varying superficial gas velocities and tip speeds, at radial position: (a)
9cm (b) 15cm