1. Proceedings of the ASME 2013 International Mechanical Engineering Congress & Exposition
IMECE2013
November 13-21, 2013, San Diego, California, USA
IMECE2013-62396
POST-CONSUMER PLASTIC SORTATION WITH THE USE OF ELECTROMAGNETIC
SEPARATION METHODS FOR RECYCLING
Connor G. Kress and Matthew Franchetti
The University of Toledo
Mechanical, Industrial, and Manufacturing Engineering Department
Toledo, Ohio, USA
ABSTRACT
In 2010, the United States generated over
31 million tons of plastic waste, and from that total,
only 8% was recycled. With demand for lower cost
plastics and public attention to environmental
concerns increasing, the expanding recycling
industry has provided an opportunity to lower raw
material costs and create sustainable jobs.
Traditionally, manual or optical methods that used
infrared technologies were utilized to sort plastic
wastes for recycling. Once these plastic wastes
were sorted, they were cleaned, shredded, and
melted into raw materials. These methods are
costly and can experience high nonconformance
rates during the sortation processes. This paper
discussed an emerging technique that utilizes a
novel process that sorts shredded plastic particles
by using electromagnetic (EM) waves and Ferro
fluids. The process involves placing various types
of shredded plastic particles of into a tank filled with
Ferro fluid. The plastic particles and Ferro fluid are
then subjected to an EM wave by the use of an EM
coil. The EM wave alters the viscosity of the Ferro
fluid and causes the shredded plastic particles to
rise and sink at different vertical levels within the
Ferro fluid tank, based on their respective densities.
This method allows for an efficient, accurate, and
low cost method to sort plastic particles as
compared to conventional technologies. This paper
provides a detailed analysis of this method in terms
of the equipment requirements, installation costs,
operation costs, and life cycle assessment (LCA).
Overviews of the model development, experimental
design, and test results are provided that
demonstrates proof-of-concept. Finally, a cost,
efficiency, and accuracy comparison of this method
to conventional methods is provided. The results of
the study indicated that the EM separation method
offers significant cost, efficiency, and accuracy
improvements over conventional methods. EM
separation method may reduce operating costs by
approximately 15-20% due to reduced equipment
and labor expenses versus convention methods.
Initial modeling and testing indicate that accuracy
rates may be increased from the 80-90% of existing
methods to nearly 100%.
INTRODUCTION

2. Since 1960, the US Gross Domestic
Product has increased from $520.5 billion to $14.6
trillion in 2010 [1]. As the United States has grown
more productive, and as more goods are
consumed, more waste is generated. Of this waste
stream, plastic refuse is problematic for society and
has experienced low recycling rates. For example,
the US generated 31 million tons of plastic waste in
2010 and of that total, only 8% was recycled [2].
With increasing demand for lower cost plastics and
heightened public attention to environmental
concerns, the expanding recycling industry has
provided an opportunity to lower raw material costs
and create sustainable jobs. A cost benefit analysis
of the existing plastic sortation and recycling
methods is necessary to better understand and
promote the increased recycling of these materials.
The process of turning plastic waste into reusable
material at an industrial rate has pushed recycling
into the 21st century. Technological advances in the
recycling field have increased the efficiency and
productivity of sortation processes. By using a
standardized approach, the various methods of
plastic recycling technology can be quantified and
compared.
Recycling rates have expanded 28% in the
past 20 years (National Association for PET
Container Resources, 2010). With demand for lower
cost plastics increasing, and increased
environmental concerns, recycling has not only
become a necessity, but a profitable business. In
just 2 years, recycling rates of plastics have
increased by 8% alone (National Association for
PET Container Resources, 2010). This is expected
to be greatly influenced by the US’s Recycling
Works Program which establishes a 75% solid
municipal waste recycling goal for 2015 (Recycling
Works Program, 2012). It also dictates that 30% of
all waste in the United States will be recycled, both
by the manufactures and the consumers. This sets
the precedent for major growth in the recycling
industry in the next several years. Along with
possible subsidies from the federal government, the
program is expected to generate 1.5 million new
jobs in both recycling and post-manufacturing waste
recovery (Recycling Works Program, 2012). The
government involvement has amazing potential for
a complete redesign of the recycling market in the
United States. The problem with the situation is that
modern technologies are rarely used in current
waste processing because the machines require
large amounts of initial capital. If federal/state
government subsidized capital for these operations,
what technologies would they use? And how would
they know that those technologies are superior to
current methods?
In order to correctly analyze the current and
possible future technologies presented, a control
medium needed to be set. Plastic waste was
chosen as a standard as its frequently recycled and
very common to nearly every locality in the U.S. this
makes it an ideal control variable to be used in
proposed recycling plants funded by the Federal
government. Landfill disposal of plastics has
significantly increased (EPA,2012) and the ease of
acquiring usable waste for large scale operations is
a desirable feature of using plastic.
Process of the Experiment
Stage 1
The goal of this experiment is to determine the
relationship between the material properties of
Ferro fluid in reaction to an Electromagnetic pulse.
Ideally a universal co-efficient can be found that
correctly determine the wave propagation in the
Ferro fluid in relation to the particle length.
Stage 2
The purpose of this stage is to produce a scale
model of the machine in order to look at the
processing accuracy and the overall viability of the
system for an industrial basis. After completing
testing, a cost-analysis of the assembly will be
conducted for the purpose of implementing stage 3
Stage 3
During this stage, the construction of a full-scale
model begins. It will be used for the actual industrial
feasibility. After construction, the efficiency’s and
costs will be compared to other market competitors.

3. The is a high probability that modeling can be of use
to predict profitability over a time scale.
The Analysis of the Testing
During the analysis of the Experiment, two forms of
testing will be used. The first stage will use
theoretical math and physics to determine the
mathematical relationship between the
Electromagnetic Pulse and the Ferro Fluid. This
relationship will further be confirmed with
experimentation. Specifically, this experiment will
generalize relationships and idealize the proof of
concept. Whereas the analysis of the second and or
third stage will be conducted largely on efficiency
and cost principles.
METHODS AND MATERIALS
The idea of grinding whole plastic
containers into particles prior to sorting allowed the
our team to focus on developing a concept that was
solely based on sorting particles (rather than both
particles and containers) in such a way that was
scalable.
A Ferro fluid is a fluid in which fine particles
of iron, magnetite or cobalt are suspended, typically
in oil, and can be manipulated with magnetic fields.
The typical size of the suspended iron particles are
in the nanometer range, but for this application a
micrometer range will be used as larger particles
tend to respond better to a magnetic field. When
the fluid is subjected to an electromagnetic wave,
the iron particles align and the viscosity changes.
Ferro Fluid
Ferro fluid is liquid that can be manipulated with
magnetic fields. For this experiment, it will act as the
fluid displaying variable Viscosity’s. Ferro fluids are
colloidal liquids composed of suspended
ferromagnetic particles in a carrier liquid. Typically
the carrier liquids are oils, water, acids, or organic
solvents. In this suspension, the addition of a
surfactant prevents the ferric particle from binding to
each other. This results in the autonomous flow
properties of the Ferro fluid when not exposed to
the Magnetic Field. Yet, as a Magnetic Field is
introduced into the system, the Ferro fluid will align
and form temporary domains in the system. These
temporary domains alter the viscosity of the Ferro
fluid. Although the Ferro fluid is magnetically active
while being exposed to EM Fields, it will
immediately lose those properties after the field is
removed. This material feature is called colloidal
liquidity, and from this characteristic the entire
experiment is possible. Because Ferro fluids can
change material properties when exposed to
electromagnetic pulses, this allows for near
complete control of the material.
Figure 1: Separation example
This is caused by the relatively small particle size
of the ferromagnetic particle in the Ferro fluid. For
this experiment, we examined Ferro fluid with a
particle size in the range of multiple micrometers'
diameter, while though technicality it is a
Magnetorheological fluid. A Ferro fluid typically in in
the nanometer range for diameter. It known that the
larger particles respond with better results to
Magnetic fields. For this experiment we will refer the
liquid as a Ferro fluid.
Electromagnetic core
In order to ascertain whether Ferro fluid has any
sort of measurable response to magnetic waves it is
necessary to devise a method to reliably generate a
magnetic field. In deciding what equipment to use to
make this generation possible, a set of design
criterion was laid out. These design qualifications
included the ability to vary performance
characteristics, the existence of experimentally
tested mathematics, as well as a set of feasibility
checks which included cost, manufacturability, and
speed of delivery.
Upon investigation it was decided that a small, iron
cored electromagnet was the best fit for our
aforementioned needs. An iron core electromagnet
is easily customized through changes in radius,

4. length and number of turns, has a well-developed
set of equations for various design types and can be
manufactured in house (in the MIME shop) quickly
and inexpensively.
Material Properties of Box
The type of plastic chosen to contain the Ferro fluid
was antistatic acrylic. It was chosen for its ability to
highly resist the building of static charge. If the box
was not antistatic then the acrylic would absorb
charge. This charge could potentially become large
enough to create voltage that could be hazardous to
both equipment and/or people. If the box were to
build charge on the surface then the EM waves and
the Ferro fluid could be effected. Careful control of
the EM waves is imperative in controlling and
understanding how the Ferro fluid reacts in the
given field. Also, some of the data acquisition will
be done digitally; this plastic should reduce the
chance of a stored charge causing a voltage
change, altering the data.
This particular acrylic was also chosen because of
its inherent resistance to deflection that could have
been caused by a net change of pressure in the
box. The acrylic is ideal for use in a pressure
vessel. When this experiment was being designed,
it was not yet determined whether or not a net
pressure would occur, therefore causing the overall
density of the Ferro fluid to fluctuate based on the
relative pressure change.
After designing and building the pressure vessel, we
conducted a static pressure test to determine the
pressure seal of the box. Here below we plotted our
results for a pressure loss resulting from the largest
theoretical pressure possible based on the design of
the vessel. This loss is roughly 1 psi loss over 6
minutes, or .06 psi per second. For a typical test
that occurs in less than 20 seconds, and has a
pressure change of less than one psi, we
determined this pressure vessel is sufficiently well
sealed, and deem it an acceptable standard for
testing.
Graph 1: pressure loss of sealed vessel
Material Properties of Ferro Fluid
The most critical property of the Ferro fluid to be
useful in plastic separation is its specific gravity. In
order to control which plastic will rise to the top of
the solution, the density of the fluid must be altered
to values that lie between the specific gravities of
differing plastics. Table 1 below shows the different
types of recycled plastics and their corresponding
specific gravity values.
Plastic
Type
Specific Gravity (g/cm^3)
Polyolefin Polypropylene .916-.925
Low-density Polyethylene .936-.955
High-density
Polyethylene
.956-.980
Non-olefins Bulk Polystyrene 1.050-1.220
Polyvinyl Chloride 1.304-1.336
Polyethylene
Terephthalate
1.330-1.400
Table 1. Specific Gravity of Various Plastics
According to the MSDS sheet for the Ferro fluid,
there is density range of .92-1.47 g/cc with a
specific product density of 1.21 g/cc at 25 degrees
Celsius. The actual density of the Ferro fluid will be
confirmed experimentally using the following
equation where P is the density, M is mass, and V is
volume:
Using an precise digital scale and an accurate
graduated cylinder, the density can effectively be
calculated. For this experiment, the specific gravity
of the sample Ferro fluid was 1.15g/cc at 25 degree
Celsius.

5. In order for any given plastic to float in the solution,
the specific gravity of the Ferro fluid must be greater
than that of the plastic. Based on this assumption, it
was concluded that an 11% change in specific
gravity is necessary in order to produce the desired
effect of separating plastic waste.
Pressure Data Acquisition
Change in density of the Ferro fluid cannot be
measured directly. Upon initial research, we
decided to use the ideal gas law to prove that there
is indeed a density change by logging a pressure
change. The two variables are related by the
following function:
P/ρ=RT
Assuming that the temperature is constant along
with R, density will change inversely with pressure.
Since the system will be closed and the box is rigid,
the volume will not change by any significant
amount. It is hypothesized that the excitation of the
Ferro fluid by EM waves will cause the density of
the fluid to increase. This will decrease the volume
of the fluid causing a vacuum to be created in the
air. Therefore, the team had to design a data
acquisition system that would account for this
negative pressure change in the air.
Two methods were proposed to measure the
vacuum effect. One was the use a mechanical
vacuum gauge, while the other was the idea to use
a digital manometer. The mechanical vacuum
gauge seemed like the likely solution because the
effects from EM waves on a digital system were
unknown. The team was afraid that the magnetic
flux would induct a current and skew the data.
However, all of the vacuum gauges that the team
found used mercury to detect and scale the
pressure change. Mercury is slightly magnetic and
could skew the data by a large percentage since the
anticipated pressure change is so small. Research
done prior to the project being handed off to the
team found that in the closed system contained with
the aforementioned box the pressure change should
be very minimal (around 1psi). The final solution
was to use a digital manometer offset from the
system, making the effect from the EM waves
negligible. The digital manometer is also far more
accurate than the mechanical vacuum gauge.
Furthermore, a pressure transducer was placed into
the Ferro fluid to examine the change in specific
gravity in real time. This pressure transducer was
selected on the basis of the following
characteristics. Firstly, it is waterproof and highly
resistant to acidic decay, as some Ferro fluids are
slightly acidic. Secondly, this pressure transducer is
also bidirectional; this allows a dynamic response to
the Ferro fluid to be ascertained when it exposed to
an Electromagnetic pulse. Thirdly, this device
produces a varying signal based on voltage, not
current. Combined with a calibrated data acquisition
system, a detailed pressure change could be
pictured accurately.
Thermal Data Acquisition
The team plans on using thermocouples to show
that there will not be a significant change in
temperature as the Ferro fluid is excited by an EM
wave. If this is proven using experimental data
taken from each thermocouple, then the method
described above can be used to measure the
pressure change of the system.
However, if there is a significant change in
temperature, then a different method relating
change in pressure and change in temperature
must be used. As stated above, one of the
assumptions that the team is making is that volume
of the box will not change significantly. In this case
Gay-Lussac’s law can be applied using the following
function to derive a change in pressure:
State 1 corresponds to the system at rest before the
Ferro fluid is excited by the EM coil and state 2 is
real time data collected as an experiment is
conducted. Pressure at state 1 will be measured
without the influence of EM waves, resulting in
much more accurate data. The offset digital
manometer will accurately measure the pressure of
the air, but there also needed to be a way to
measure the initial pressure of the fluid. The team
has decided to use a very accurate pressure
transducer to find this value. Change in pressure of
the air will prove the concept of density change but

6. accurate measurements of the pressure of the fluid
will allow the team to quantify the change in density
values. Temperature of state 1 will be measured
very shortly after the EM coil is turned on so that
there is a presence of a magnetic field. This may
cause the data to be inaccurate. However, the goal
in comparing the temperature at state 1 with a given
temperature found in a predetermined state 2 is to
find a ratio of the two. By subjecting both
measurements to the same magnetic field, the
expectation is that the error at both state 1 and 2
will be negligible, resulting in an accurate ratio that
can then be plugged into the above equation to
solve for pressure at state 2.
In order to account for the possible error caused by
EM waves on the digital measurement system a
separate experiment was designed to show the
relation between the actual temperature of the
system and the measured value from the
thermocouples. This is imperative to determine
because the effect on the measurement system
from the magnetic field coupled with the Ferro fluid
is unknown. Temperature will be measured right
before EM waves are emitted and again right after.
The system will then be heated up and the test will
be conducted again until a sufficient number of data
points have been collected. Then the actual
temperature of the system can be plotted vs. the
digital readout corresponding to the given
temperature to find the relationship between the
two. Using this relationship, the digital readout can
be interpolated back to find the actual temperature.
Having an accurate temperature will result in a more
accurate derivation of the density at each state.
Magnetic Field Sensor
For this experiment two magnetic field sensors we
determined to be needed in order to quantify the
strength of the field propagated throughout the
system. The effect on the digital measurement
system is unknown so some sort of calibration is
necessary. One sensor will be placed just under the
coil and the other will be placed directly opposite on
the other side of the box. Before testing occurred, a
series of tested were conducted to find a
relationship between the magnetic field strength and
the amount in which the digital measurement
systems are affected in order to increase accuracy.
For this experiment we chose to use Pasport
magnetic sensors. These sensors are pre-calibrated
and consist of a sensor in a housing that allows for
easy use and high quality data. Additionally, this
system also allows multiple sensors to allow for
greater data stream to confirm static conditions.as
well as a comparison for calibration of
instrumentation in the NI system.
Software
In this experiment, two type of software were to be
used. The software for stage one will be Labview,
the accompanying software with the National
instruments Data acquisition system. In our
experiment a Series X DAQ box was used. The
data acquisition system is USB based and allows
for a relative simple and inexpensive setup yet
produces a high quality of accuracy. This system
was also chosen on because of it closed metal
frame/chassis that allows for radiant
electromagnetic energy to be dissipated safely
through a ground. The DAQ was used to collect
data, and analyze it for material qualities.
Channel Basis Device Range Calibration
A1 Pressure Transducer 0-500spi Purchased
A2 Thermo K type TC -200&1350
F
Icebath/
Boiling
A3 Thermo K type TC -200&1350
F
Icebath/
Boiling
A4 Thermo K type TC -200&1350
F
Icebath/
Boiling
Table 2: Thermocouple channels
Calibration of the system was conducted within 24
hours of experimentation in order to lower the
likelihood of a calibration error. For the pressure
transducer, the manufacturer had pre-calibrated the
device. We also confirmed this basis by testing at 1
Atm. additionally; we seconded the calibration by
using a different device, a Pasport Absolute
pressure gauge. Both of these methods yielded
near exact calibration for testing the pressure.
Calibration for each k type thermocouple was
achieved by recording variation from temperatures
ranging from 33! (IceBath) To 214! (Boiling water).

7. The handheld thermometer and an infrared optical
temperature measurement device seconded these
results.
The second software will be ANSY Maxwell. This
program will be used to model the 3D wave
propagation of the electromagnetic pulse. The
modeling of this experiment will likely occur in stage
2 in order to better determine the exact physic
present in the exposed Ferro fluid.
Testing Method
This experiment was conducted in three major
parts.
1. Ambient to EM exposure
2. EM exposure to Ambient
3. Static EM exposure
For each section we tested three voltages, and from
these tests we would obtain our data samples. In
the first part, an EM pulse was added in order to
observe the change in Ferro fluid. Secondly, the EM
pulse was removed halfway through sampling to
observe the change in the density. For the third part
of the experiment, we looked at the system with the
ambient conditions. We also looked at a static test
to confirm the test data accuracy.
DATA
Graph 2: Ambient to EM exposure, 5 Volts
Graph 3: Ambient to EM exposure, 10 Volts
Graph 4: Ambient to EM exposure, 15 Volts
Graph 5: EM exposure to Ambient, 5 Volts

8. Graph 6: EM exposure to Ambient, 10 Volts
Graph 6: EM exposure to Ambient, 15 Volts
Graph 7: tempurature Readings Ambient to EM
exposure
Graph 8: temperture Readings EM exposure to
Ambient
Magnetic Gauss Readings
For this section we chose a 10V data sample. In this
sample you can see the variation in Gauss output
from one side of the electromagnet to the other side
of the pressure vessel near the pressure transducer.
As you can see, there is typically minimal Gauss
field near the pressure transducer. This data was
selected on the basis that it best represents what
happened in a average test.
Graph 9: Gauss Dispersion throughout the Box
Manometer readings
During the Calibration and testing it was determined
that the Net air pressure of the pressure vessel did
not change. This was originally discovered by
ambient readings of the manometer, while testing
there appeared to be no net change in pressure.
This was confirmed using a highly accurate
Absolute pressure measurement device.
CONCLUSIONS
After conducting this experiment it we believe that it
is in fact possible to manipulate the internal
pressures of Ferro fluid using a predetermined
electromagnetic pulse. After applying a low pass
filter we were able to determine the resulting net
change of pressure and specific gravity.
As you can see above, when exposed to the pulse,
the Ferro fluid completely reorders and causes a
decrease of specific gravity. When this phenomena
first appeared we assumed it to be an error in either
our program or in lab setup. But after doing some
research, we believe this to be a natural quality of
colloidal liquids. Therefore we have concluded and
proved that Ferro fluid’s specific gravity can rapidly

9. be changed via a magnetic pulse, while still
preserving the temperature of the Ferro fluid.
Possible sources of error
This particular experiment presented some sources
of error. Firstly, human error was a possible creation
of error. This is largely in part to the number of
different people that helped conduct the experiment.
Secondly, it is possible that error appeared from our
computer/DAQ system. Although these systems are
highly accurate, we did not have a National
Instruments Expert on hand to oversee data
acquisition.
Lastly there is the possibility of the magnetic pulse
affecting the measurement devices and disrupting
the voltage signal. After concluding this experiment,
static tests were taken to help determine whether
electromagnetic waves corrupted signals. In the
electromagnetic coil thermocouple, a major
disruption was observed. We concluded that its
extremely close proximity to the EM pulse certainly
led to its corruption. This was corrected by taking
the temperature before/after the coil was active. As
for the other two thermocouples, very little
disruption was observable, both in dynamic and
static tests. Finally, after conducting static tests we
were able to determine a slight level of
electromagnetic disruption in the pressure
transducer. This has been quantified and has been
used to confirm actual pressure changes.
TestType Volts PEm (psi) PAm(psi) ρAm (g/cm^3) ρEm(g/cm^3) Deltaρ (g/cm^3) % Change
Static 5.4V 14.66513 14.75494 1.157 1.149957601 0.007042399 0.608677501
Static 10.3V 14.52481 14.76228 1.157 1.138388187 0.018611813 1.608626852
Static 14.4V 14.52491 14.78893 1.157 1.136344608 0.020655392 1.785254241
Dynamic 5.4V 14.02982 14.35228 1.157 1.131005005 0.018952596 1.638080923
Dynamic 10.3V 13.77698 14.39044 1.157 1.107676931 0.030711256 2.654386884
Dynamic 14.4V 13.73137 14.40381 1.157 1.102985341 0.033359267 2.883255596
Table 3: % Change in Density
Further Research
From this experiment, we will progress onto stage
two of this experiment. We deem this proof of
concept to be valid. In the future we hope to re-
examine the core design and the frequency of the
voltage to maximize and refine the magnetic pulse
to produce an accurate change in the specific
gravity of the Ferro Fluid.
APPENDIX A
Single Layer Iron Cored Solenoid Magnetic
Flux Density Calculation
Figure 2: Solenoid coil design
Where:

10. Using these:
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