534 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
particles, part of the each collected sample is fed into a
Mastersizer, from Malvern Panalytical, for size distribution
analysis. The Mastersizer measures particle size distribution
using laser diffraction. The results are typically presented as
the percentage of particles within each size range.
SINGLE PARTICLE EXPERIMENT
RESULTS
The different motion directions, forward and backward,
have been observed for particles in hopping mode and
surfing mode experimentally. Backward motion means
particles move in the direction opposite to the traveling
wave field, and it has been observed and suggested that
this was due to the second harmonic wave of ETW field
(MasudaWashizu and Iwadare, 1987, MasudaWashizu and
Kawabata, 1988). By utilizing the different transport direc-
tions, Masuda and coworkers tried to separate biological
cells (MasudaWashizu and Iwadare, 1987) Machowski and
coworkers (MachowskiBalachandran and Hu, 1995) per-
formed the separation experiments on sand and pulverised
alumina powders. In chapter 4, the additional analysis is
provided based on the simulation results, which shows that
the backward motion due to the effect of harmonic wave is
only noticeable when the particle size is large or frequency
is high. In this section, the motion direction of large size
particle of ballotini have been researched and recorded.
Figure 8 shows one of the typical motions of ballotini
of size between 300 and 350 µm. The images were extracted
from high-speed camera videos and superimposed. In the
experiment, the voltage amplitude was 1500 V and the
frequency was 60 Hz. The wave direction was rightward
and the motion direction of the particle was leftward. In
the frame capture process, the time interval between each
frame was the same, so the time interval was the same. The
different distances between the particle points means that
the velocity of particle was fluctuating.
Using the software of Tracker, the variation of par-
ticle position with time can be recorded accurately. And
the recording frame rate is 2134 f/s. Therefore, the particle
motion characteristics such as, moving velocity, accelera-
tion, and levitation height can be analyzed quantitatively.
The relationship between the average velocity and frequency
is shown in Figure 9. The negative velocities at other fre-
quencies in the range of 5 to 180 Hz means particle exhib-
iting backward motion consistently. And there was a prime
frequency showing the highest particle speed.
An important experimental phenomenon was the
backward motion exhibited by large particles of ballotini
in surfing mode. It suggests that DEP becomes more domi-
nant as the particle size increases. The dielectrophoretic
forces contributes to the backward motion. Therefore, large
particles with low charge more easily move backward.
Considering that DEP is volume related, DEP hardly
affects the motion of small particles. Additionally, the influ-
ence of frequency varies in proportion to the size of par-
ticles. Therefore, different sizes of particles can potentially
be separated by their different motion directions at a proper
designed frequency. This give the guidance for the design of
separation system.
PARTICEL TRANSPORT AND
SEPARATION RESULTS
The study examined particles across four size ranges: 30 to
50 µm, 75 to110 µm, 220 to 280 µm, and 300 to 350 µm.
Figure 10 illustrates the correlation between recovery rate
and frequency. Origin software was utilized to generate a
spline line connecting the data points. A crossover point is
observed on both the forward and backward recovery rate
Figure 8. Superimposed frames from high-speed camera video showing surfing mode backward
motion of ballotini particle at 60 Hz, 1500 V
particles, part of the each collected sample is fed into a
Mastersizer, from Malvern Panalytical, for size distribution
analysis. The Mastersizer measures particle size distribution
using laser diffraction. The results are typically presented as
the percentage of particles within each size range.
SINGLE PARTICLE EXPERIMENT
RESULTS
The different motion directions, forward and backward,
have been observed for particles in hopping mode and
surfing mode experimentally. Backward motion means
particles move in the direction opposite to the traveling
wave field, and it has been observed and suggested that
this was due to the second harmonic wave of ETW field
(MasudaWashizu and Iwadare, 1987, MasudaWashizu and
Kawabata, 1988). By utilizing the different transport direc-
tions, Masuda and coworkers tried to separate biological
cells (MasudaWashizu and Iwadare, 1987) Machowski and
coworkers (MachowskiBalachandran and Hu, 1995) per-
formed the separation experiments on sand and pulverised
alumina powders. In chapter 4, the additional analysis is
provided based on the simulation results, which shows that
the backward motion due to the effect of harmonic wave is
only noticeable when the particle size is large or frequency
is high. In this section, the motion direction of large size
particle of ballotini have been researched and recorded.
Figure 8 shows one of the typical motions of ballotini
of size between 300 and 350 µm. The images were extracted
from high-speed camera videos and superimposed. In the
experiment, the voltage amplitude was 1500 V and the
frequency was 60 Hz. The wave direction was rightward
and the motion direction of the particle was leftward. In
the frame capture process, the time interval between each
frame was the same, so the time interval was the same. The
different distances between the particle points means that
the velocity of particle was fluctuating.
Using the software of Tracker, the variation of par-
ticle position with time can be recorded accurately. And
the recording frame rate is 2134 f/s. Therefore, the particle
motion characteristics such as, moving velocity, accelera-
tion, and levitation height can be analyzed quantitatively.
The relationship between the average velocity and frequency
is shown in Figure 9. The negative velocities at other fre-
quencies in the range of 5 to 180 Hz means particle exhib-
iting backward motion consistently. And there was a prime
frequency showing the highest particle speed.
An important experimental phenomenon was the
backward motion exhibited by large particles of ballotini
in surfing mode. It suggests that DEP becomes more domi-
nant as the particle size increases. The dielectrophoretic
forces contributes to the backward motion. Therefore, large
particles with low charge more easily move backward.
Considering that DEP is volume related, DEP hardly
affects the motion of small particles. Additionally, the influ-
ence of frequency varies in proportion to the size of par-
ticles. Therefore, different sizes of particles can potentially
be separated by their different motion directions at a proper
designed frequency. This give the guidance for the design of
separation system.
PARTICEL TRANSPORT AND
SEPARATION RESULTS
The study examined particles across four size ranges: 30 to
50 µm, 75 to110 µm, 220 to 280 µm, and 300 to 350 µm.
Figure 10 illustrates the correlation between recovery rate
and frequency. Origin software was utilized to generate a
spline line connecting the data points. A crossover point is
observed on both the forward and backward recovery rate
Figure 8. Superimposed frames from high-speed camera video showing surfing mode backward
motion of ballotini particle at 60 Hz, 1500 V