Tribo-Electrostatic Beneficiation of Recycled
PolymersReview of Past Work and Discussion of an Improved
Separation System
Rodger Butler, Kyle FlynnST Equipment & Technology, Needham MA
Motivation
•Dry Processing of Recycled Polymers (Recycled Carpet) for Beneficial Use
•Recovery of Nylon with Ash Content Less than 5% • Removal of Calcium Carbonate
•Separation of Nylon from Polypropylene
•Others?
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Outline
Conventional Electrostatic Separation (ESS)
New Technology - STET Tribo-electrostatic Belt Separator
Applications for The STET ESS
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Review of Previous Work using ESS for Polymers
ST Equipment & Technology LLC, Confidential
Conventional ESS Technology – High Tension Roll (HTR) Separators
Separates conductors from non-conductors (metal from plastic)
All particles must contact drum surface
Feed rates <5 TPH/m drum width
Lower particle size limit: ~0.075 mm
Limitations
Elder and Yan, 2003
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Conventional ESS Technology – Free Fall Separators
Elder and Yan, 2003
Physical footprint
Single stage separation
Must maintain laminar flow
Avoid particle-to-particle contact in separation zone
• Large electrode gap
• High applied voltage
• Low particle loading
• Low throughput / capacity
Too large – No separation
Too small – Collects on Electrodes
Motion influenced by aerodynamics
Lower particle size limit of ~0.10 mm
Particle Size Effects
Limitations
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Triboelectric Series for Plastics
Triboelectric Series for Plastic
Positive End +
Acrylonitrile-Butadiene- Styrene ABS
Polypropylene PP
Polycarbonate PC
Polyamide (Nylon) PA
Polyethylene Terephthalate (Polyester) PET
Polystyrene PS
Polyethylene PE
Polyvinyl Chloride PVC
Polytetrafluoroethylene PTFE
Negative End -
1. G. Dodbiba, Magnetic and Electrical Separation, Vol. 11, No. 1-2, pp. 63-92 2. Hersh, S.P., and Montgomery, D.J., Text. Res. J., Vol. 25, pp. 279
• The Triboelectric series differs slightly based on the researcher reporting the work.
• The STET Separator relies on particle-to-particle charging, and is able to separate materials with small differences in work function.
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Summary of Past Work
• I.I. Inculet – Inst. Phys. Conf., (1991)• Used a fluidized bed tribo-charging device• Separated Acrylic, Nylon, PE or PVC achieving 95%
purity.
• G. Dodbiba – Akita University, Japan (2001 – 2003)• Air cyclone – particles charged by contact with cyclone• Separated PET from PE with grade higher than 95%• Separated ABS, PS and PP with grades of 85 – 92%
• C. Xiao – American Plastics Council • Rotating drum charging device with free fall separator• Separation of PC from PVC
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STET Electrostatic Separator
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STET Electrostatic Separator
Small gap and intense agitationHigh electric field strength with moderate applied voltage (typ. 8 - 20 kV)High efficiency multi-stage separation through charging/recharging & internal recycle
Very low residence times ~1 sec
Wide particle size range <0.001 to ~0.5 mm
High capacity Up to 1,400 ft^3/hr
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STET Electrostatic SeparatorPlant Location Country Separators Comission
DateNew England Power Somerset, MA 1 1995
Duke Energy Roxboro, NC 2 1997
CPSG Brandon Shores, MD 2 1999
Scottish Power Longannet, Scotland 1 2002
Jacksonville Electric SJRPP Jacksonville, FL 2 2003
SMEPA Morrow, MS 1 2004
NB Power Belledune, NB 1 2005
RWE Didcot, England 1 2005
PP&L Brunner Island, PA 2 2007
TECO Big Bend, FL 3 2008
RWE Aberthaw, Wales 1 2008
EDF Energy W. Burton, England 1 2008
ZGP Janikowo, Poland 1 2011
KOSEP YONG HEUNG 5 & 6 1 2014
Siekerki Poland 1 2016
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Consistent Product from Variable Feed
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Recommended Applications
• Completely Liberated Material• Ideally a Two Component Mixture• Dry and Free Flowing• Fine - 100% less than 500 microns
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Thank You!
Thank You!ST Equipment & Technology
101 Hampton Ave
Needham, MA 02494
+1-781-972-2300 www.steqtech.com
Kyle FlynnManager, Process Engineering
(+1) [email protected]
Rodger ButlerDirector Contract Administration
(+1) [email protected]
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Backup Slides
• The Following Slides are Included as Supporting Material
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STET Proven ResultsFe
ed
Resu
lts
Calcium Carbonate
9.5% SiO2
< 1% SiO2
89% CaCO3Recovery
Improved Brightness
Talc
58% Talc
42% Magnesite
95% Talc
77% Recovery
88% Talc
82% Recovery
Barite Fly Ash
200,000 TPY
82%BaSO4
3.78 (SG)
8 % - 25% LOI
92% BaSO4
4.21 SG
74% Recovery
Processed ash:
2.5% LOI
ST Equipment & Technology LLC, Confidential
STET Electrostatic Separator
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Value Created (USD per ton product)
Economic Value
YESMaybe
NO
ST Equipment & Technology LLC, Confidential
STET Electrostatic Separator
ST Equipment & Technology LLC, Confidential