REVIEW OF POST-CONSUMER PLASTIC PREPARATION IN AUSTRIA AND NEW
APPROACHES FOR FEEDSTOCK RECYCLING
M. Bauer1, M. Lehner1,
1University of Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria

e-mail:markus.bauer@unileoben.ac.atAbstract
For reasons of security in supply and high plant availabilities in feedstock recycling, substantiated knowledge about postconsumer plastics streams, their management and particular mechanical preparation processes is essential. Therefore, aflow chart has been developed based on data from literature, statistics and plant visits to illustrate the structure of theexisting preparation processes, their interlocking and the underlying material streams in Austria. This provides the basis
to figure out new concepts to supply adequate feedstock for material recycling like polyolefins and polystyrene (POS) richfractions. Therefore, tests of two sorting devices, the near- infrared sorting unit (NIR- unit) and the sorting centrifuge havebeen conducted. The investigated plastic-rich materials are mixed plastics (MP) and refused derived fuel of high calorificvalue (RDF-HC). The tests show that the sorting centrifuge produces POS fractions of high purity (100 %) and recovery(100 %), but it is an apparatus of high complexity. A succesfull application for sorting of post-comsumer plastics is indoubt. The NIR- unit creates lower purities (90 %) and recovery rates (80 %) but is a proven technology in plastic sorting.

Keywords: post- consumer plastic streams, plastic sorting, feedstock recycling, near-infrared sorting, sorting centrifuge
1.

Introduction

Today the highest volumes of raw materials in man-madeproduction are plastics. Low weight, low cost,
multifunctional applicability and analogous materialproperties compared to others ensure their leading
position. The steadily increasing consumption of plastics
results in high material streams leading to an enormous
challenge for sustainable management of the postconsumer material. Mechanical recycling only partly
covers the need of material recovery. The majority ofthese valuable hydrocarbons ends up in landfills or as
heating fuels, in other words is converted directly toalmost non-recoverable CO2 and H2O. In contrast
feedstock recycling comes across this problem andincreases the sustainability of plastic utilization byrecovering the hydrocarbon molecules.
To guarantee material supply of feedstock recycling
plants and to secure high plant availabilities asubstantiated knowledge about post-consumer plastics
streams, their management and particular mechanicalpreparation processes is crucial.
2.

Materials and Methods

Phase IThe current situation of plastic containing waste streams
of different plastic contents in Austria has been
investigated. Austria was chosen as an example becauseof sufficient data availability. The result of this basic study
is a flow chart, relating the found waste streams with theestablished preparation technologies and recycling,
recovery and disposal systems. The scheme combines
information and data from literature [1], [2] and statistics[3]. Moreover, visits of waste treatment plants andmeetings with plant operators complete the usedsources. The objective is to illustrate the structure of theexisting preparation processes and their interlocking.
Based on the current situation, starting points for new
concepts to absorb appropriate plastic fractions likepolyolefins and polystyrene (POS) are figured out.
Referring to the different compositions of the material
streams and the given technical embedding diverse
separation and sorting equipment undergo further tests.
Phase II
Tests include dry processing as well as wet processing.
Today, latter is very unusual for preparing post-consumer
plastics, because most of the material is incinerated.
Furthermore, the tests are conducted on pilot scale
plants mostly at laboratories of the corresponding
equipment suppliers or universities.
In particular the focus is on two plastic-rich waste
streams:• Residues of packaging waste sorting plants
named mixed plastics (MP) which go topreparation plants for producing refusedderived fuels (RDF)• Refused derived fuels of high calorific value(RDF-HC) for co-combustion at the primaryburner in cement kilns
The plastic content of both of these fractions is more than
50 % per mass. A rough specification is shown in Table
1, in which all the shares are referring to mass.
The sorting tests aim to gain information about thesorting efficiency expressed in the form of material

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013

purities and recoveries and to calculate mass balances.
POS are separated from the rest.
Table 1: Rough specification of MP and RDF- HCMP
RDF- HC
Particle size [mm]30 - 250< 30Bulk density [kg/m³]
50 - 100
200 - 250
Water content [%]10 - 20
15 - 25
POS content [%]
> 60
> 50
Impurities [%]
< 40
< 50
Calorific value [%]
> 25
> 20
Halogens [%]<3<1
Based on literature research and the experiences fromphase I following apparatuses have been investigated:• near- infrared sorting unit (NIR- unit) respective
dry processing• sorting centrifuge respective wet processing
Depending on the material stream’s properties especiallythe particle size the NIR- units and the sorting centrifuge
are intended to be applied at different positions along thepreparation chain. Consequently the MP of larger particle
size is processed on the NIR-unit and the smaller
particles in the RDF-HC are tested on the sorting
centrifuge.
3.

Results and Discussion

Phase I
Austria’s total post- consumer plastic of about 500 000
t/a in 2009 splits into five main waste streams. They aresummarized in Table 2 in percent by mass and order of
their plastic content.
Table 2: Plastic-rich waste streams in Austria
Plastic content[%]
Production waste
100Packaging waste
70
Domestic commercial waste
25
Shredder waste
25
Municipal waste
10
Either directly or after different preparation steps morethan 70 % per mass of post- consumer plastics are used
for heat and/or energy recovery in mono or cocombustion plants. Slightly more than 20 % aremechanically recycled. The remaining amounts are
system losses or get landfilled. The predominating
sorting technology for the majority of post- consumer
plastic streams is the near-infrared sorting unit, apartfrom simple sorting technologies like ballistic separators,
air classifiers and manual sorting for quality control.
Further commonly used equipment for crushing areimpact mills and for material stream splitting are drumsieves.
Phase II
The test results of the NIR- unit and the sorting centrifuge
in pilot- scale are summarized in Table 3. The first line inTable 3 shows the share of the POS fraction and the rest
referring to the input mass stream respectively.

Table 3: Results of the sorting tests
NIR- unit
Sorting centrifuge[%][%]
Share POS
4551
Share rest5549
Sum
100
100
Purity of POS
90
100
Recovery of POS
80
100
Purity and recovery are defined in equation (1) and (2).
ci,j = mi,j / mj,tot(1)
ci,jpurity [kg/kg]
mi,jmass of material i in the stream j [kg]mj,tottotal mass of the stream j [kg]ri,j = mi,j / mj,input(2)
ri,jrecovery [kg/kg]
mi,jmass of material i in the stream j [kg]mj,input mass of the material i in the input [kg]The test results show clearly that the separation of POS
conducted by the sorting centrifuge is of high efficiency.
But on the other hand the sorting centrifuge is a very
complex apparatus with many influencing parameters,
which caused a couple of problems during the test
procedure. Originally the sorting centrifuge was not buildfor processing this type of impure materials like RDFHC. As consequence there is a doubt that stable andtrouble free operation for sorting RDF- HC in commercial
plants could be guaranteed. The NIR- unit produces POSof lower purity and recovery but apart from that it is aproven sorting technology for all kind of plastic-rich waste
streams. Choosing smart interconnection of several NIRunits will help to increase POS recovery.
4.

Conclusions

Based on the current main post- consumer plastic
streams, the frequently used preparation technologies
and recycling, recovery and disposal systems, thecurrent structure of post- consumer plastic management
in Austria is illustrated. Consequently, the potential of
producing POS enriched plastic fraction could be
estimated. Tests of diverse sorting equipment showpromising results to create new concepts for efficient
post- consumer plastic preparation of high material
recovery.
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[2] C. Neubauer, B. Walter: Behandlung von gemischten
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Umweltbundesamt GmbH, 2008.
[3] Bundesministerium für Land- und Forstwirtschaft,Umwelt
undWasserwirtschaft
eds.:
Bundesabfallwirtschaftsplan 2011 – Teil 1. Vienna:
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7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013