Final report
Polypropylene recovery from
post consumer carpets
Report into the recovery of polypropylene from post consumer carpets
Executive summary
In the UK, up to 500,000 tonnes per annum of post consumer carpets are sent to landfill. Currently, there are very few
recycling processes in existence to handle this waste stream. One option is to size reduce synthetic post consumer
carpets for use in equestrian surface applications. However, this is a relatively low value application and it should be
possible to gain a higher value material from recovered post consumer carpets.
Axion Consulting were commissioned by Envirolink Northwest to investigate a recycling option for post consumer
carpets, in response to an application for technical support made by Carpet Recycling UK.
The aim of the project was to research and develop a recycling process for post consumer carpets made from
polypropylene (PP). Working closely with Carpet Recycling UK, the project was to assess whether a recycled PP product
could be produced from post consumer carpets.
The project consisted of a combination of demonstration trials and laboratory work, all of which took place at Axion
Polymers in Salford. The project involved the following stages:
 Size reduction of the carpets using a granulator fitted with a 15mm screen;
 Screening of the carpets with a 12mm flip-flop screen;
 Laboratory scale extrusion of the clean granulated material; and
 Physical properties testing of the extruded polymer.
There were three samples of carpet tested:
 PP post industrial carpet; and
 PP post consumer carpet mix sourced from a household waste recycling centre (HWRC) in Salford and from a
carpet recycler in Leicestershire.
 PP post consumer tufted carpet sourced from a household waste recycling centre (HWRC) in Salford.
An initial sample of post consumer carpet was tested with a portable near infrared (NIR) machine to identify which
carpets were made from PP. Only the PP carpets were granulated and screened. Subsequent preparations for the
laboratory extrusion work indicated that the granulated material was not entirely PP and contained contamination.
Assessment of the sample showed fibres from the carpets, which were identified as nylon and polyethylene
terephthalate (PET). An attempt was made to extrude the material but it was not possible to maintain the extrusion
strand. This issue highlighted the problem of carpets containing a range of fibres made from different polymers.
A second sample of post consumer carpets was sourced from the same HWRC as the first sample, but this time only
carpets of a tufted construction were included. All the carpets were thoroughly tested with a Fourier Transform InfraRed
(FTIR) machine. Only carpet pieces, where both the pile and backing fibres had been confidently identified as PP were
processed.
The granulation trial, in terms of size reduction, was a success. The carpets required manual size reduction to
approximately 20x20cm pieces before granulation, to ensure the carpets did not tangle around the granulator shaft and
block the machine. Additionally the machine was fed slowly to allow plenty of time for the material to be processed and
to prevent blockages from occurring. The granulator size reduced the material and successfully released the pile fibres
from the backing fibres.
The granulated material was then processed over the flip-flop screen. The results of the trial showed that 38% of the
material was oversized and 59% was undersized with a 3% loss. The oversize fraction was the desired product and
assessment of the material showed it was significantly cleaner than the feed material. The undersize fraction contained
a high proportion of small fibres and dust/dirt contamination. The yield loss in the screening trial was high and this was
due to the combination of the granulator and flip-flop screen sizes. For a 12mm flip-flop screen the carpet should ideally
only be granulated to approximately 20-25mm. If a smaller granulated fraction is produced, as in this trial, the flip-flop
screen should then be smaller, at 6-8mm, in order to reduce yield losses.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
2
Samples of both post industrial PP carpet and the clean granulated post consumer carpet were extruded, moulded into
plaques and bars and physical properties tested. The post industrial sample was used as the benchmark against which
the post consumer fraction was compared. The physical tests showed that both the fractions were good but there were
measurable differences between the two samples.
Physical properties test
Melt Flow Rate (at 230°C,
2.16kg)
Tensile
Elongation @ Yield
Elongation @ Break
Density
Ash
Units
Post industrial sample
Post consumer sample
Mpa
%
%
g/cm3
%
6
22
7.3
35.1
1.15
17
52
23
10.1
28.8
1.023
10
The differences between the two samples are not unexpected as the post industrial material was manufactured recently,
where as some of the post consumer samples may be 10 to 15 years old and made with different techniques and grades
of PP. Not only is the age of the material likely to cause variations, different carpet manufacturers are likely to use
different grades of PP causing more variations. Therefore it is anticipated that the physical properties of the extruded
fibres from post consumer carpets is likely to change between batches of carpets.
A direct comparison with virgin PP is difficult due to the presence of fillers in the carpets samples. However, in general
terms the physical properties of the post industrial sample are good compared to what would be expected from a filled
PP product.
It is thought that the post industrial extruded polymer could be used in injection moulding applications, although further
research with moulding companies would be required to verify the suitability of the material. The post consumer
polymer could potentially be used in medium to lower grade injection moulding applications, such as plant pots or
buckets.
The main conclusions from the project are:
 Post industrial carpet can be processed into a product with good physical properties which has potential for use in
a range of applications;
 Post consumer carpet, consisting of entirely PP fibres, can be recycled into a product with physical properties
making it suitable for use in medium grade applications;
 However, the extruded product from the post consumer carpet is only acceptable if the carpets can be correctly
identified and sorted. Correct identification and segregation of post consumer carpets into an entirely PP
fraction is critical to the viability of a commercial process to recycle carpets; and
 Carpets which contain a mix of polymers, including PP, produced a fraction which was not suitable for extrusion
and hence the end market for mixed synthetic carpets is still likely to be equestrian surfaces.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
3
Table of contents
1
Introduction ................................................................................................................................ 6
1.1
Types of carpets................................................................................................................. 6
1.2
Existing recycling techniques ............................................................................................... 8
1.3
Existing end markets for post consumer carpets .................................................................... 9
2
Demonstration trials ................................................................................................................. 10
2.1
Sourcing of the carpets for the trials ................................................................................... 10
2.2
Initial demonstration work.................................................................................................. 13
2.3
Size reduction ................................................................................................................... 15
2.3.1
Granulation .......................................................................................................... 15
2.3.2
Results of granulation trial ..................................................................................... 16
2.3.3
Discussion of results .............................................................................................. 16
2.3.4
Shredding............................................................................................................. 17
2.3.5
Results of shredding trial ....................................................................................... 17
2.3.6
Discussion of results .............................................................................................. 17
2.3.7
Alternative size reduction options ........................................................................... 18
2.4
Screening and cleaning ...................................................................................................... 19
2.4.1
Flip-flop screen ..................................................................................................... 19
2.4.2
Results of flip-flop trial........................................................................................... 20
2.4.3
Discussion of results .............................................................................................. 22
2.4.4
Alternative cleaning options ................................................................................... 22
2.5
Extrusion .......................................................................................................................... 23
2.5.1
Laboratory extrusion ............................................................................................. 23
2.5.2
Physical properties comparison of extruded products ................................................ 23
2.6
Discussion of demonstration trial results .............................................................................. 25
3
Waste carpets volumes in Northwest England ........................................................................ 26
3.1
Carpet specification ........................................................................................................... 26
3.2
Composition of mixed carpet waste ..................................................................................... 26
3.3
Source of waste carpets ..................................................................................................... 26
3.3.1
Industrial sources.................................................................................................. 26
3.3.2
Commercial waste sources ..................................................................................... 26
3.3.3
Domestic waste sources ........................................................................................ 27
3.3.4
Total carpet waste ................................................................................................ 27
4
Proposed recycling flowsheet for waste PP carpets ................................................................ 28
4.1
Mass balance for recycling PP carpets ................................................................................. 29
5
Commercial viability of recycling post consumer carpets ....................................................... 32
6
Conclusions ............................................................................................................................... 37
Appendices ............................................................................................................................................ 38
Appendix 1 - Carpet Recycling UK ‘Tufted PP carpet waste arising in NW’, 2009 .............................. 38
List of figures
Figure 1 Schematic of woven carpets ..................................................................................................................... 6
Figure 2 Schematic of tufted carpets ...................................................................................................................... 7
Figure 3 Flow diagram of demonstration trials ....................................................................................................... 10
Figure 4 Samples of carpets which were granulated .............................................................................................. 11
Figure 5 Sample of carpet showing backing and pile fibres ..................................................................................... 11
Figure 6 Second backing layer peeled back to show primary backing layer and latex ................................................ 12
Figure 7 Sample of contaminated carpets ............................................................................................................. 13
Figure 8 Granulator set up .................................................................................................................................. 15
Figure 9 Granulated carpet .................................................................................................................................. 16
Figure 10 Shredded post consumer carpets .......................................................................................................... 17
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
4
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Flip-flop screen at Axion Polymers ......................................................................................................... 19
Flip-flop screen processing the granulated carpets .................................................................................. 20
Oversize output from flip-flop ............................................................................................................... 21
Undersize output from flip-flop ............................................................................................................. 21
PP test bars moulded from post industrial carpets .................................................................................. 24
PP test bars moulded from post consumer carpets .................................................................................. 25
recycling process for waste PP carpets .................................................................................................. 28
Option 1 mass balance for the recycling of PP carpets ............................................................................ 29
Option 2 mass balance for the recycling of PP carpets ............................................................................ 30
List of tables
Table
Table
Table
Table
Table
Table
1
2
3
4
5
6
Granulator mass balance ......................................................................................................................... 16
Mass balance for flip-flop trial .................................................................................................................. 20
Physical properties results from the carpet samples .................................................................................... 23
HWRC case studies ................................................................................................................................. 27
Economic payback calculation for option 1................................................................................................. 33
Economic payback calculation for option 2................................................................................................. 35
Glossary
FTIR
NIR
PET
PP
Fourier Transform Infra Red Spectroscopy
Near Infra Red Spectroscopy
Polyethylene Terephthalate
Polypropylene
Acknowledgements
Axion Consulting would like to thank Carpet Recycling UK for their input and assistance with the project.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
5
1
Introduction
Carpets have been in use for many years and the quantities entering the UK waste stream are in excess of half a million
tonnes per year. Currently in the UK the recycling rate for carpets is less than 2%, with only a few companies involved
and recycling processing only in development stages.
Carpets are considered to have high carbon footprints as they contain virgin plastic manufactured from petrochemicals.
The manufacturing process to produce the virgin raw materials for carpets can be energy and carbon intensive.
The aim of this project was to research and develop a recycling process for carpets made from polypropylene (PP).
Working closely with Carpet Recycling UK the project was to assess whether a PP product could be produced from the
carpets.
The two types of carpet considered by this project were:
 Post industrial carpet which has never left the manufacturing site and is therefore clean; and
 Post consumer carpets, including off-cuts from installation and uplifted flooring which is dirty.
Recycling of the post consumer carpets was the main focus of work for the project.
1.1
Types of carpets
There are various types of carpets in the domestic market. The two most common are:
 Woven; and
 Tufted.
Figure 1 and Figure 2 show diagrams of tufted and woven carpets to illustrate the differences between the two styles.
Figure 1 Schematic of woven carpets1
Woven carpets are manufactured by weaving the carpet pile onto other fibres with a loom. Woven carpets tend to
contain a range of coloured yarns to produce intricate patterns. The manufacturing process also tends to be quite slow.
The fibres onto which the carpet pile is woven can be polyester, whilst the pile itself tends to be PP.
1
http://www.armelcarpet.com/images/WovenDiag.gif
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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Figure 2 Schematic of tufted carpets2
Tufted carpets are the most common type for use in domestic applications. They are manufactured by attaching the pile
fibres to a backing layer. The pile fibres can be natural materials such as wool or synthetic materials such as PP. A latex
compound is then used to bond the fibres to the backing layer. A second backing layer is added to the carpet,
sometimes this can be made of hessian but it can also be manmade fibres such as PP. The second backing layer
provides stability to the carpet.
Various types of materials can be found in carpets including:
 Plastics and rubber:
o PP;
o Polyester/PET;
o Nylon;
 Natural fibres:
o Wool;
o Hessian/Jute;
There are a wide variety of carpet manufacturers and the age of post consumer carpet found in the waste stream can
vary from a few years to over 15 years. End of life carpets can contain significant quantities of dust/dirt, which need to
be removed during the recycling process.
2
http://www.fine-flooring.com/TuftedDiagA.gif
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
7
1.2
Existing recycling techniques
Research undertaken by Axion into carpet recycling indicates that recycling processes do exist abroad and significant
work has already been conducted into suitable processes. In particular, both the United States and Europe have been
carrying out research into carpet recycling for a number of years.
Founded in 2002, the Carpet America Recovery Effort (CARE) is a joint industry-government non-profit organisation.
Their mission is to develop market based solutions for recovering value from post consumer carpet. However in America
over 80% of the carpets handled by CARE were made from nylon and only 8% were PP.3 Carpets in America also tend
to have deeper piles than UK carpets and the recycling technologies developed in the USA typically involve shearing of
the pile from the carpet backing, rather than shredding or granulation. For example, InterfaceFLOR in Georgia, America,
has a recycling process which shears off the pile fibres from the carpets. The main focus for the process is the recovery
of nylon 6 and 66 for use in new carpet tiles, but a PP fraction is created by the process which is then sold on4.
In Europe, in the late 1990’s, extensive work was done by the European carpet industry to develop a recycling route for
post consumer carpets. The project involved the following stages5:
 The RECAM (Recovery of Carpet Materials) Project. The aim of RECAM, which was funded by the European
Community, was to develop an economically feasible, closed loop system for post consumer and post industrial
carpet waste. The project studied the collection, identification and sorting of carpets as well as the recovery of
high grade materials and energy from residual fractions. The project was completed in 1999;
 Development of the technology. This involved finding or developing the necessary technical equipment and tools
for the recycling process. One element of this was COCARE, a coding system to allow for easy identification of
carpets; and
 Pilot plant. Carpet Recycling Europe (CRE) was established in 1998 with the aim to implement the findings from
the RECAM project. The project involved the building of the first automated sorting plant for carpets in Mainz,
Germany. It was the intention of the project to use the pilot plant to gather data to allow for an economic,
technical and environmental assessment of the carpet recycling process. The plant was able to process
approximately 3.5 tonnes per hour. Although the plant demonstrated technical feasibility, the economic
conditions were unfavourable, due to landfill being the cheaper option at the time. Because of this the plant
closed in August 2002. The project concluded that although technically feasible, carpet recycling would require
more favourable economic conditions for the process to become viable.
The work completed by RECAM and CRE provided useful know how into the recycling of carpets.
In Germany in 1999 Polyamid 20006, the largest nylon 6 carpet recycling facility, was built. The plant reclaimed post
consumer carpet from all over Europe and utilised chemical depolymerisation and re-polymerisation of nylon 6 and
extrusion compounding of nylon 66. The plant also recovered PP which was sold for use in fibre reinforced concrete
panels. Again due to difficult economic conditions and a lack of suitable feed material the plant shut in June 2003 7,8.
Currently in the UK, there is no well developed recycling sector for post consumer carpets. The UK's first carpet recycler
was Swindon based Greenback Recycling which was set up only a few years ago. However Greenback does not produce
an extruded product from the carpets they receive.
3
4
5
6
7
8
CARE 2008 Annual Report - accessible as www.carpetrecovery.org
http://www.interfaceflor.com/Default.aspx?Section=3&Sub=6&Ter=24
http://www.gut-ev.de/en/frames_issues_rec.htm
http://www.ptonline.com/articles/200205cu2.htm
http://www.concentro.de/downloads/fallstudie_3_en.pdf
http://etd.gatech.edu/theses/available/etd-08222008-132753/unrestricted/subbiah_valli_200812_mast.pdf
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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1.3
Existing end markets for post consumer carpets
There are various end markets which currently exist for material from post consumer carpets. The main, relatively low
value, end market in the UK is the equestrian or the horticultural market. In the equestrian market the material
recovered from the carpets is used as an additive to sand based all-weather surfaces. surface material and laid on the
ground. Once the carpet has been used as an equestrian surface the plastics cannot be recovered further.
Although not a well developed option in the UK, the materials recovered from carpets have the potential for use in a
range of every day products including:
 Plastic park benches;
 Road cones;
 Compost bins;
 Plastic car parts;
 Soil erosion protection;
 Underlay;
 Insulation;
 Building products; and
 Sports surfaces.
The use of materials recovered from carpets in the manufacture of new carpets, closed loop recycling, is currently
uncommon.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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2
Demonstration trials
The overall project plan was to demonstrate a possible recycling process for post consumer PP carpets.
The flow diagram in Figure 3 shows the various demonstration trials completed as part of the project. The three main
stages were:
 Size reduction by granulation;
 Screening of the granulated material with a flip-flop screen to remove fines; and
 Laboratory scale extrusion trials and physical properties testing.
Figure 3 Flow diagram of demonstration trials
Carpet Recycling Trials
Post-consumer PP carpets
Granulation of carpets at
Axion Polymers
Screening of granulated
carpets with flip-flop
screen at Axion Polymers
Sample of granulated
carpet
Sample of screened
granulated carpet
Extrusion and physical properties testing of samples
2.1
Sourcing of the carpets for the trials
The project involved collecting post consumer carpets from the Cobden Street HWRC in Salford and a carpet recycler in
Theddingworth, Leicestershire.
The initial trial used carpets which were tested with a handheld Near Infrared (NIR) Spectrometer to identify the
polymers the carpets were made from. The sample comprised of both woven and tufted carpets. Most of the carpet
pieces were large and had clearly been uplifted and rolled up. There were a few small off-cut pieces which were clean
and appeared to have not been used.
A second quantity of carpets was also sourced from the same facility and was tested with a Fourier Transform Infrared
(FTIR) machine to identify the polymers present. The second sample consisted of only tufted style carpets. The
photographs in the figures below show the various pieces of carpet.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
10
Figure 4 Samples of carpets which were granulated
Figure 5 Sample of carpet showing backing and pile fibres
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
11
Figure 6 Second backing layer peeled back to show primary backing layer and latex
Figure 5 and Figure 6 show tufted carpets but with subtle differences. Tufted carpets have tufts individually inserted
into a lattice backing layer by a needling technique. A latex compound is then coated onto the backing to anchor the
tufts in place. An additional backing layer is then added to provide stability and strength. In Figure 5 the additional
backing layer is also a ‘scrim’ or lattice i.e. the same as the lattice layer onto which the tufts were initially attached,
which gives the backing a mesh like appearance. In Figure 6 the additional backing layer is an artificial ‘felt’ like fabric
made from PP. Peeling the ‘felt’ layer back shows the latex compound and lattice backing layer onto which the tufts
were inserted. The tufts, lattice layer and ‘felt’ in both of the above samples are all made from PP.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
12
2.2
Initial demonstration work
Prior to any trials being conducted on post consumer carpet a small amount of initial test work was conducted with post
industrial carpet.
The post industrial carpet sample would form the benchmark against which the post consumer carpet could be
compared. It was anticipated that the results from the post industrial carpet would be as good as could be obtained for
recycled carpet, as the carpet has never been laid and therefore was not contaminated with dirt or dust.
Testing of the post industrial carpet comprised of:
 Melting small pieces of the carpet - this was necessary in order to be able to granulate the material using the
laboratory scale granulator;
 Granulation of the carpet with a 3mm screen;
 Extrusion of the granulated carpet; and
 Moulding of test plaques and bars to conduct physical properties testing on the extruded polymer.
The results from the initial post industrial carpet trial were very promising and hence the project proceeded according to
the plan in Figure 3. Prior to granulation the carpets were assessed with a hand held NIR scanner and only the carpets
with a PP signal were processed. During the preparations for the extrusion stage of the trial it was discovered that the
carpets were not entirely PP and the granulated material contained contamination in the form of PET and nylon, see
Figure 7.
Figure 7 Sample of contaminated carpets
In Figure 7 there are visible fibres which have not melted, which were identified as PET and nylon. Both PET and nylon
have higher melting points than PP and hence did not melt in the extrusion preparation stage.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
13
The contamination meant that the extrusion process would need to operate in excess of 300°C to ensure all the fibres
melted and extruded correctly. In turn this would have a significant detrimental effect on the physical properties of the
PP component. Based on this a second sample of post consumer carpets was sourced which were visually identified as
of a tufted construction. These pieces were thoroughly tested with an FTIR machine to ensure all fibres within the
carpets were PP.
The following sections report on the processing of the second sample of post consumer PP carpets.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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2.3
Size reduction
The first stage of the recycling of post consumer carpets is a size reduction process. The two main size reduction
techniques are:
 Granulation; and
 Shredding.
2.3.1 Granulation
A small scale, hand fed granulator with a 15mm screen at Axion Polymers was used for the granulation trial. Figure 8
shows a photograph of the granulator used for the trial.
The aim of the trial was to test the ability of the granulator at size reducing the carpets and to assess the output product
from the granulation process.
The carpets had to be manually size reduced prior to being fed into the granulator to pieces approximately 20-30mm in
size. This was to prevent the carpet pieces from becoming entangled in the granulator shaft and blocking the machine.
Figure 8 Granulator set up
The pieces of carpets were fed by hand into the top of the granulator. The granulated material comes out at the bottom
of the granulator and is sucked through to the collection bag. The material passes through a cyclone, prior to the
collection bag, which removes some of the dust from the granulated material.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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2.3.2 Results of granulation trial
Due to the manual way in which the granulator was fed it was not possible to measure the throughput. The material
was purposefully fed slowly to ensure the system would not block and hence the time taken to process the material
would not reflect the actual throughput rate which could be achieved in a commercial scale process.
Table 1 Granulator mass balance
kg
%
Feed 11.97 100%
Granulation
kg
%
Granulated material 11.70 98%
kg %
Losses 0.27 2%
Figure 9 Granulated carpet
2.3.3 Discussion of results
The granulator trial was successful. The granulator did not block and appeared to be able to process the carpets with
relative ease. However it was necessary to manually size reduce the carpets prior to granulation to prevent tangling
around the granulator shaft. In a commercial process a pre size reduction stage is likely to be required. It is probable
that the pre size reduction stage would require some manual input, albeit the size reduction itself could be done with a
cutting machine.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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The granulator successfully size reduced the material. A good degree of separation was achieved with a significant
quantity of the pile fibres being released from the backing fibres. The granulation action was also sufficient to remove
some of the latex from the pile fibres.
2.3.4 Shredding
As a comparison to the granulation trial a shredding trial was conducted by Carpet Recycling UK at MachTech Service in
Rochdale, UK.
2.3.5 Results of shredding trial
Figure 10 Shredded post consumer carpets
The carpet material used in the shredder trial was different to that used in the second granulator trial, hence the
different coloured fibres seen in the photographs. The shredded carpets were taken from the initial sample of carpets
which were not exclusively PP. The carpets had been identified as having both PP pile and PP backing but the sample
had not been segregated into woven and tufted carpets. It is thought that the non-PP warp fibres in the woven carpets
were the source of the contamination seen in the partially melted material from the granulation trial.
2.3.6 Discussion of results
In contrast to the granulated carpets the shredded material contained more pieces of small complete carpet. The size of
the fibres in the shredded material is smaller than in the granulated material. There are some noticeable pieces of latex
within the shredded sample, where as in the granulated sample there are not many latex pieces visible.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
17
The pile in the granulated sample pulls apart to create a cotton wool like material but this is not the case with the
shredded carpet, where the fibres have remained as short twisted piles.
2.3.7 Alternative size reduction options
The main alternative technique for size reducing carpets is the shearing technique used in America. The shearing
technique works by shaving the pile fibres from the backing layers of the carpet. This produces two fractions; one
consisting of the pile fibres and one of the backing layers. Typically the latex backing is disposed of, whilst the carpet
pile fibre is processed through a screen or dry cleaner, then extruded and pelletised.
In the past shearing has been considered an unsuitable technique for the recycling of carpets in the UK, as the pile on
UK carpets is generally too short. Development work on shearing of short-pile carpet has now started but it is likely that
the yield of pile fibres recovered by shearing would be too low for the process to be economically viable.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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2.4
Screening and cleaning
Post consumer carpet can contain significant quantities of dirt and other forms of contamination. In order to have a
clean fraction for the extrusion stage the granulated material was processed over a flip-flop screen to remove the fines
and dust.
The flip-flop screen was chosen as the technique to clean the granulated carpet because of the action it creates. The
movement of the flip-flop screen back and forth causes the material to jump up and down as it travels down the screen.
This motion results in a high G-force screening action. It was hoped that this would cause the dust, dirt and possibly
latex compound to be liberated from the granulated carpet.
2.4.1 Flip-flop screen
Figure 11 shows the flip-flop screen used for the trial, which has a 12x12mm deck.
Figure 11 Flip-flop screen at Axion Polymers
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
19
2.4.2 Results of flip-flop trial
Figure 12 Flip-flop screen processing the granulated carpets
Table 2 Mass balance for flip-flop trial
Losses
Granulated kg
%
material
6.36 100%
kg
%
0.20 3%
Screening
Oversize kg
%
fraction 2.41 38%
Undersize kg
%
fraction
3.75 59%
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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Figure 13 Oversize output from flip-flop
Figure 14 Undersize output from flip-flop
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
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2.4.3 Discussion of results
The flip-flop screen was able to process the granulated material. The results of the trial showed that 38% of the
material was oversized and 59% was undersized, with a 3% loss of material. The oversize fraction was the desired
product and a visual assessment of the material showed it was significantly cleaner than the feed material. The
undersize fraction contained a high proportion of small fibres and dust/dirt particles.
The yield loss in the screening trial was high, which was due to the screen sizes used in the two trials (granulation and
flip-flop screen). For a 12mm flip-flop screen the carpet should ideally only be granulated to approximately 20-25mm.
If a smaller granulated fraction is produced, as in this trial, ideally the flip-flop screen should then be smaller, at 6-8mm,
in order to reduce yield losses.
During the trial it was observed that the material tended to get caught as it travelled down the screen and rolled like
tumble weed. On occasions manual intervention with a broom was required to keep the material moving down the
screen.
Although the flip-flop screen was able to remove the dust and dirt, it would be advisable to conduct further work with
other types of screens and screen sizes in order to select the most suitable screen for processing of carpets.
2.4.4 Alternative cleaning options
A Pla.to dry cleaning unit could be used as an alternative method to remove the dust and fines from the size reduced
carpet. The Pla.to dry cleaning unit has a screen with beaters which knocks the material against itself and the screen,
with the dust being removed from the carpet through the screen. The Pla.to dry cleaner does not require water to clean
the material which is an advantage. However the cost of Pla.to dry cleaner is in the region of €200,000, which is
significantly more than a basic flip-flop screen.
As the results from the flip-flop screen trial were promising the decision was made that a trial with a Pla.to dry cleaner
was unnecessary.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
22
2.5
Extrusion
The following two samples were extruded using a laboratory scale extruder:
 Post industrial material; and
 Post consumer granulated and flip-flopped carpet.
2.5.1 Laboratory extrusion
In order to be able to process the carpets with the laboratory equipment at Axion Polymers the carpets required partial
melting. The partial melting was achieved by placing small samples of granulated carpet in a vacuum forming machine
for a short period of time. After partial melting the carpets were granulated to 3mm, the particle size required for the
extruder feed system.
Both samples were extruded using the laboratory scale extruder without any complications.
An attempt was also made to extrude the initial sample of carpet which contained PET and nylon contamination.
However, the contamination caused the strand from the extruder to blow and the material spluttered from the nozzle.
The material had been dried prior to extrusion and so its inability to extrude was not due to moisture content.
2.5.2 Physical properties comparison of extruded products
The samples of post industrial and post consumer carpet underwent a number of physical properties tests:
 Melt Flow Rate (MFR). The MFR is the number of grams of polymer that can be pushed out of a capillary die of
standard dimensions (diameter 2.095 mm, length 8.0 mm) under the action of standard weight (2.16 kg for PP,
at 230°C) in ten minutes (ASTM Standard 1238). The usual melt index range is from less than 1.0 (called
fractional) to up to 100 for injection moulding. The higher the MFR, the easier the PP fills the plastic mould and
the easier the injection or blow moulding process. As the MFR increases, some of the physical properties, such
as impact strength decrease;
 Tensile strength (Ultimate) (MPa). The ultimate tensile strength is the maximum stress a material can withstand
when subjected to tension, compression or shearing. Typical PP tensile strengths range from 20-80 MPa9;
 Elongation at point of yield (%). The elongation at point of yield measures the elongation to the point where the
maximum stress is applied;
 Elongation at break (%). The elongation at break measures the elongation at the point of rupture;
 Density (g/cm3); and
 Ash (%). The ash test indicates the content of filler (typically chalk) within the polymer.
Table 3 Physical properties results from the carpet samples
Physical properties test
MFR (at 230°C, 2.16kg)
Tensile
Elong @ Yield
Elong @ Break
Density
Ash
Units
Mpa
%
%
g/cm3
%
Post industrial sample
6
22
7.3
35.1
1.15
17
Post consumer sample
52
23
10.1
28.8
1.023
10
Table 3 shows the results of the physical properties testing of the two samples. The post industrial sample formed the
base case against which the post consumer material was compared. The physical property tests showed that both the
fractions were good but there were measurable differences between the samples.
9
http://encyclopedia.stateuniversity.com/pages/21823/tensile-strength.html
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
23
The post industrial sample has a MFR of 6, whilst the post consumer sample MRF was 52. This means the post
consumer sample may be easier to mould, but is likely to have a lower impact strength. The tensile strengths of the two
samples are similar. The post industrial sample has a lower elongation at yield than the post consumer sample, but a
higher elongation at break. The post industrial sample stretched 7.3% before the maximum force was reached, whilst
the post consumer sample stretched 10.1% before maximum stress was achieved. However the post industrial sample
was stretched 35% before breaking, whereas the post consumer sample was only stretched 29%. The post industrial
sample had 17% filler content, while the post consumer material had 10%.
The differences between the samples are not unexpected as the post industrial material has been manufactured
recently, where as some of the post consumer samples may be 10 to 15 years old and made with different
manufacturing techniques and polymers. Different manufacturers are likely to use different grades of PP with different
quantities of fillers. The melt flow index of the PP may change during manufacturing of the carpets due to the sheer
forces created in the manufacturing process. Therefore it is highly probable that different batches of post consumer
carpet will demonstrate different physical properties to those stated above due to variations in the age, type and
manufacturer of the carpets.
A direct comparison of either result with virgin PP is difficult due to the presence of fillers in the carpet samples. In
general terms the post industrial sample had good physical properties compared to what would be expected from a
virgin filled PP.
The colour of the extruded PP is influenced by the colour of the carpets forming the feed material. Figure 15 and
Figure 16 shows the test bars which were made from the post industrial and post consumer carpets. Both extruded
polymers are brown in colour, with the post consumer sample being darker than the post industrial.
It is likely that the PP produced from post consumer carpets would require the addition of master batch to make the final
product black. Black PP will be more attractive to potential customers and hence should be sold for a higher price.
Figure 15 PP test bars moulded from post industrial carpets
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
24
Figure 16 PP test bars moulded from post consumer carpets
It is thought that the post industrial extruded polymer could be used in injection moulding applications, although further
research with moulding companies would be required to verify the suitability of the material. With the post consumer
polymer it is expected that there would still be a market for the material, likely to be in medium to lower grade injection
moulding applications such as plant pots or buckets.
2.6
Discussion of demonstration trial results
Overall the demonstration trials were successful and the project showed that an extruded PP product could be produced
from the post consumer carpets.
The granulator was able to size reduce the carpets without any problems, but care was taken to ensure the feed rate
was slow enough to prevent blockages. The granulator was a suitable size reduction technique for carpets and
produced a slightly different style of output to the shredded material. The shredded particles were smaller and less of
the fibres were released. The granulator output consisted of a cotton wool like material and more of the fibres had been
liberated.
The flip-flop screen produced an oversize fraction which was noticeably cleaner, with significantly less dirt/dust
contamination than the feed material. However, too much of the granulated material was captured in the undersize
fraction. This was due the screen size of the flip-flop screen being slightly too large for the particle size of the
granulated material, hence the loss to the undersize fraction. The trial proved that a screening technique, such as a flipflop, could be used to remove the dust and dirt.
The extrusion trial was very successful. The results of the physical properties testing showed that both the post
industrial and post consumer samples of extruded PP were of a good standard and quality; the post industrial sample
had slightly better physical properties than the post consumer sample. Both samples appeared suitable for injection
moulding applications, with the post consumer material likely to be used in medium to low grade injection moulding
applications such as plant pots or buckets.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
25
3
Waste carpets volumes in Northwest England
The following section is based on information provided by Carpet Recycling UK. The full report by Carpet Recycling UK
can be found in Appendix 1.
The aim of the task was to calculate the volume of post consumer carpet waste available in the Northwest of England.
3.1
Carpet specification
Based on the results obtained from the demonstration trials in this project, the waste carpet material must meet the
following specification:
 Each piece of carpet to be positively identified as having PP pile fibre;
 Carpet type to be of a tufted construction;
 All the backing fibres to be positively identified as PP;
 The carpet to be dry;
 No heavy contamination (for example paint, nails); and
 Acceptable for manual handling (for example no pet urine or odours).
3.2
Composition of mixed carpet waste
Research indicates that 45% of mixed carpet waste is identified as having a pile fibre made from PP. Of this 45%, 70%
has a synthetic backing. Based on sales the split between tufted and woven carpets is expected to be approximately
85:15 respectively. Typically, woven carpets have backing fibres containing polyester so these carpets can be
discounted. This means that 27% of mixed carpet waste meets the PP fibre and tufted construction criteria.
3.3
Source of waste carpets
There are three key sources of carpet waste:
 Industrial;
 Commercial; and
 Domestic.
3.3.1 Industrial sources
In the Northwest of England there is one carpet manufacturing site which produces post industrial carpet waste meeting
the specification. The quantity generated is approximately 20 tonnes per month.
3.3.2 Commercial waste sources
The following results are based on a case study with Flooring UK, a flooring contractor based in Southport and serving
mainly public sector housing contracts. Flooring UK generates approximately ten bales of tufted PP carpets per month,
weighing 3.33 tonnes in total, which gives an annual quantity of approximately 40 tonnes.
Assuming that it would be feasible to collect similar amounts from eleven flooring retailers or contractors in the region,
this would give 450 tonnes per annum.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
26
3.3.3 Domestic waste sources
The main route for the disposal of waste carpets from domestic sources is through Household Waste Recycling Centres
(HWRC).
Compositional analysis of the residual waste collected at HWRCs indicates that the carpet content can range from 5%15%. A conservative estimate of 8% has been used in the following calculations.
In order for carpet to be collected at HWRCs there must be space on site for a suitable storage container to keep the
carpets dry.
Table 4 shows two case studies for HWRCs in the Northwest of England.
Table 4 HWRC case studies
Area
HWRC
sites
Sites which
could collect
carpets
Residual waste to
landfill from suitable
sites
Carpet
waste
(8%)
Assuming a 75%
availability rate for
carpet waste
Merseyside
municipal
waste
16
12
90,000 tonnes
7,200 tonnes
5,400 tonnes
Cheshire
16
6
15,750 tonnes
1,260 tonnes
945 tonnes
Using the information in the above table an estimate of the carpet waste airings in the whole of the Northwest of
England was completed.
It was assumed that 60% of HWRC sites could take a suitable container for carpet collections, meaning 63 of the 103
HWRCs in the Northwest region could be considered.
The residual waste from Merseyside and Cheshire HWRCs accounts for 30% of the total waste in the Northwest region.
Extrapolating the case study results of 6,345 tonnes per annum of carpet waste from Merseyside and Cheshire to the
whole of the Northwest region gives 21,150 tonnes per annum of waste carpets.
However this figure is for all carpet waste and, as stated previously, the composition of mixed carpet waste is such that
only 27% of the material will meet the specification. Hence 5,710 tonnes of post consumer tufted PP carpets could be
collected from HWRCs in the region.
3.3.4 Total carpet waste
The calculations show the following volumes of waste:
 Industrial waste - 240 tonnes;
 Commercial waste - 450 tonnes; and
 Domestic waste – 5,710 tonnes.
Total waste arisings of carpet which meets the specification is estimated at 6,400 tonnes per annum.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
27
4
Proposed recycling flowsheet for waste PP carpets
Figure 17 shows the proposed process for the recycling of post consumer carpets. One of the main aspects of the recycling process is the correct identification of the carpets to
ensure that only PP carpets are processed through the recycling plant.
The recycling plant requires three main processing stages:
 Size reduction;
 Screening/cleaning; and
 Extrusion.
Figure 17 recycling process for waste PP carpets
Overall stages required for recycling for PP carpets
Collection of
carpet waste from
a range of sources
Delivery of carpet
waste to central
processing
location
Polymer
identification and
testing of carpets
Segregation of PP
and mixed
polymer carpets
Size reduction of
carpets
Screening of size
reduced carpets
Waste fraction
Non-PP carpets
and PP woven
carpets
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
Fines fraction
28
Extrusion of
cleaned carpets
PP pellets
4.1
Mass balance for recycling PP carpets
Two options for the recycling of post consumer PP carpets have been proposed:
 Option 1 involves buying in bales of pre-sorted tufted PP carpet at £80/te; and
 Option 2 involves buying in size reduced tufted PP carpets at £250/te.
Figure 18 Option 1 mass balance for the recycling of PP carpets
PP carpet recycling mass balance – Option 1
Power cost
Stage operating 8 hours,
5 days a week
5000 te/year of
Baled sorted tufted
PP carpet
Cost £80/te
De-baling
stage
Power cost
Stage operating 8 hours,
5 days a week
5000 te
Size reduction
stage
Power cost
Stage operating 8 hours,
5 days a week
Power cost
Stage operating 24 hours,
5 days a week
Screening
stage
Yield = 80%
Extrusion
stage
Yield = 97%
5000 te
4000 te
1000 te
120 te
Waste to landfill
1120 te
Disposal cost £60/te
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
29
3880 te of PP pellet
Sell for £500/te
Figure 19 Option 2 mass balance for the recycling of PP carpets
PP carpet recycling mass balance – Option 2
5000 te/year of
Sorted and size
reduced tufted PP
carpet
Cost £250/te
Power cost
Stage operating 8 hours,
5 days a week
Power cost
Stage operating 24 hours,
5 days a week
Screening
stage
Yield = 80%
Extrusion
stage
Yield = 97%
4000 te
1000 te
3880 te of PP pellet
Sell for £500/te
120 te
Waste to landfill
1220 te
Disposal cost £60/te
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
30
The option 1 mass balance in Figure 18 has the following assumptions:
 The process is split into two stages:
o Stage one is the de-baling, size reduction and screening stages. These operate 8 hours a day for 5 days
a week;
o Stage two is the extrusion stage which operates 24 hours a day for 5 days a week;
 A feed quantity of 5,000 tonnes per year of post consumer carpets pre-sorted into tufted PP carpets costing
£80/te delivered;
 It has been assumed that 100% of the carpets delivered to the plant will meet the specification;
 All of the carpets are shredded and screened with a yield of 80%;
 The undersize fraction from the screen has no economic value and will be sent to landfill to be disposed of; and
 The oversize fraction from the screen is extruded. The extrusion process produces a small quantity of waste
which also has to be landfilled.
The option 2 mass balance in Figure 19 has to following assumptions:
The process is split into two stages:
o Stage one is the screening stages which operates for 8 hours a day for 5 days a week;
o Stage two is the extrusion stage which operates 24 hours a day for 5 days a week;
 A feed quantity of 5,000 tonnes per year of sorted and size reduced post consumer tufted PP carpets costing
£250/te;
 It has been assumed that 100% of the carpets delivered to plant will meet the specification;
 The size reduced carpets are screened, again with a yield of 80%;
 The undersize fraction from the screen has no economic value and will be sent to landfill for final disposal; and
 The oversize fraction from the screen is extruded. The extrusion process produces a small quantity of waste
which also has to be landfilled.
It should be noted that the landfill disposal cost will increase to at least £68/t in April 2010 when landfill tax
increases to £48/t
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
31
5
Commercial viability of recycling post consumer carpets
The project has shown that from a technical perspective post consumer carpets can be recycled into an extruded PP
material, which has potential use in a range of end markets.
However the commercially viability of the process is dependent on the following factors:
 A regular supply of feed material, which meets the specification;
 Rigorous identification techniques to ensure that only PP material is processed through to extrusion. If too many
carpets containing non-PP fibres were processed the resultant product would be of too low a grade to be
extruded and hence would not achieve the same market value as the PP pellets; and
 Research conducted as part of this project indicated that the key issue for many carpet recycling plants is the
economics of the process. If landfill is a cheaper option than processing, which it has been and in some places
may still be the case, then the economics of the recycling process can be unfavourable.
Based on the information obtained during the project a payback calculation has been completed for each option to
assess the commercial viability of the recycling process.
The payback calculation for option 1 uses the following assumptions:
 The plant capacity is 7,500 tonnes per annum;
 The project did not select any specific processing equipment and therefore the capital cost estimate is based on
Axion’s own recycling equipment experience. The capital cost takes into account the purchasing of:
o Carpet identification equipment; a hand held NIR sorter(s) or a bench top FTIR machine for quality
control;
o 4te per hour de-baler;
o 4te per hour size reduction machine;
o Screening machine;
o Buffer storage silos before extrusion;
o Three 400kg extrusion machines;
o Conveyors;
o Fire protection;
 The calculation assumes that a suitable site and building for the processing facility would be rented rather than
purchased, hence the inclusion of an £80,000 rental cost;
 The power cost break down consists of:
o Stage 1 of the process operates for 2,000 hours per annum and 5,000 tonnes of carpet can be de-baled,
shredded and screened. The power cost for stage 1 is £14,000 per annum based on 10p/kW hr;
o Stage 2 requires three 400kg extruders to meet the necessary capacity. This stage runs for 6,000 hours
per annum and processes 4,000 tonnes of carpet which costs £252,000 per annum.
o Total power cost is £266,000;
 The labour costs breakdown consists of:
o Labour for stage 1 - de-baling, size reduction and screening:
o Three operatives required for stage 1 working 8 hours a day, 5 days a week at a job cost of £18,000 per
annum per person, gives a labour cost of £54,000;
o Labour for stage 2 - extrusion:
o Extrusion process will operate 24 hours a day, 5 days a week which requires three shifts with three
operatives per shift, with an additional allowance of two personnel, at a job cost of £18,000 per
annum per person, gives a labour cost of £198,000;
o A technical manager at £25,000;
o Total labour cost is £277,000;
 Other additional operating costs include compliance costs such as quality control, health and safety and
environmental considerations;
 It has been assumed the cost to the processor for the waste carpet to be delivered to the processing site will be
£80/te;
 The small quantity of material, from the screening and extrusion process, which requires disposal to landfill costs
£38,100 per annum;
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
32


The extruded PP pellet has been estimated to sell for £500/te creating just under £2 million revenue per annum;
and
The calculation shows the margin per annum is over £800,000, which gives a payback time of just over one year.
Table 5 Economic payback calculation for option 1
Capacity
Capital cost of plant
Operating costs
Power Stage 1
Basis of operation for debaling, size reduction and screening
De-baler
Size reduction
Screening
Cost (assuming 10p/kW hr)
Power costs
Overall Equipment Effectiveness (OEE)
Plant input for shredding
Stage 1 power costs
Power Stage 2
Extruder capacity
Basis of operation for extrusion
Extrusion (3 x 400kg extruders)
Cost (assuming 10p/kW hr)
Power costs
Overall Equipment Effectiveness (OEE)
Material for extrusion
Stage 2 power costs
Total power costs
Labour
Labour costs stage 1
3 operators at 8 hours per day with job cost £18,000
Labour costs stage 2
3 shifts with 3 people per shift + 2 spare with job cost £18,000
Technical management
Total labour costs
tpa
te/hr
£
7,500
3.57
1,000,000
hr/yr
kW hr/hr
kW hr/hr
kW hr/hr
£/hr
£/te of feed
%
te/yr
£/yr
2,000
20
60
20
10
2.80
70%
5,000
14,000
te/hr
hr/yr
kW hr/hr
£/hr
£/te of feed
%
te/yr
£/yr
£/yr
1.0
6,000
600
60
63
70%
4,000
252,000
266,000
£/yr
54000
£/yr
£/yr
£/yr
198000
25,000
277,000
Others
Rent and rates 10,000 sq ft at £8/sq ft
£/yr
80,000
Compliance - quality, safety, environment
£/yr
30,000
Insurance
£/yr
15,000
Total Operating Costs
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
668,000
33
Table 5 Economic payback calculation Table 5 cont’d
Cost of delivered feed
Feed cost
Disposal cost (at £60/te)
£/te
£/yr
£/yr
80
400,000
38,100
PP pellet - value of product
£/te
500
Quantity of PP pellet
te/yr
3,880
Revenue from PP product
£/yr
1,940,000
Total revenue
£/yr
1,940,000
Margin
£/yr
833,900
Revenue
Payback time (years)
1.2
The payback calculation for option 2 uses the following assumptions:
 The plant capacity is 7,500 tonnes per annum;
 The project did not select any specific processing equipment and therefore the capital cost is estimated based on
Axion’s own recycling equipment experience. The capital cost takes into account the purchasing of:
o Carpet identification equipment; a hand held NIR sorter(s) or a bench top FTIR machine for quality
control;
o Screening machine;
o Buffer storage silos before extrusion;
o Three 400kg extrusion machines;
o Conveyors;
o Fire protection;
 The calculation assumes that a suitable site and building for the processing facility would be rented rather than
purchased, hence the inclusion of an £64,000 rental cost;
 The power cost break down consists of:
o Stage 1 of the process operates for 2,000 hours per annum and 5,000 tonnes of carpet can be screened.
The power cost for stage 1 is £2,800 per annum based on 10p/kW hr;
o Stage 2 requires three 400kg extruders to meet the necessary capacity. This stage runs for 6,000 hours
per annum and processes 4,000 tonnes of carpet which costs £252,000 per annum;
o Total power cost is £254,800;
 The labour costs breakdown consists of:
o Labour for stage 1 - de-baling and screening;
o One operative required for stage 1 working 8 hours a day, 5 days a week at a job cost of £18,000 per
annum per person gives a labour cost of £18,000;
o Labour for stage 2 - extrusion:
o Extrusion process operating 24 hours a day, 5 days a week will require thee shifts with three operatives
per shift with an additional allowance of two personnel, at a job cost of £18,000 per annum per
person, gives a labour cost of £198,000;
o A technical manager at £25,000;
o Total labour cost is £241,000;
 Other additional operating costs include compliance costs such as quality control, health and safety and
environmental considerations;
 It has been assumed the cost for the sorted and shredded carpet to be delivered to the processing site will be
£250/te;
 The small quantity of material, from the screening and extrusion process, which requires disposal to landfill costs
£38,100 per annum;
 The PP pellet has been estimated to sell for £500/te creating just less than £2 million revenue per annum; and
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
34

The calculation shows the margin per annum is £47,100 which gives a payback time of 17 years.
Table 6 Economic payback calculation for option 2
Capacity
Capital cost of plant
Operating costs
Power Stage 1
Basis of operation for screening
Screening
Cost (assuming 10p/kW hr)
Power costs
Overall Equipment Effectiveness (OEE)
Plant input for screening
Stage 1 power costs
Power Stage 2
Extruder capacity
Basis of operation for extrusion
Extrusion (3 x 400kg extruders)
Cost (assuming 10p/kW hr)
Power costs
Overall Equipment Effectiveness (OEE)
Material for extrusion
Stage 2 power costs
Total power costs
Labour
Labour costs stage 1
1 operators at 8 hours per day with job cost £18,000
Labour costs stage 2
3 shifts with 3 people per shift + 2 spare with job cost £18,000
Technical management
Total labour costs
tpa
te/hr
£
7,500
3.57
800,000
hr/yr
kW hr/hr
£/hr
£/te of feed
%
te/yr
£/yr
2,000
20
2
0.56
70%
5,000
2,800
te/hr
hr/yr
kW hr/hr
£/hr
£/te of feed
%
te/yr
£/yr
£/yr
1.0
6,000
600
60
63
70%
4,000
252,000
254,800
£/yr
18,000
£/yr
£/yr
£/yr
198,000
25,000
241,000
Others
Rent and rates 8,000 sq ft at £8/sq ft
£/yr
64,000
Compliance - quality, safety, environment
£/yr
30,000
Insurance
£/yr
15,000
Total Operating Costs
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
604,800
35
Table 6 Cont’d
Cost of delivered feed
Feed cost
Disposal cost (at £60/te)
£/te
£/yr
£/yr
250
1,250,000
38,100
PP pellet - value of product
£/te
500
Quantity of PP pellet
te/yr
3,880
Revenue from PP product
£/yr
1,940,000
Total revenue
£/yr
1,940,000
Margin
£/yr
47,100
Revenue
Payback time (years)
17.0
The two payback calculations show that the more economically favourable scenario is to purchase sorted bales of tufted
PP carpet and to size reduce the material as part of the process rather than purchasing already size reduced material.
The main issue with the second option is the high cost of the feed material. Both processes have similar overheads and
revenue but the feed costs are significantly different, hence the difference in the payback times.
If the cost of the feed material in option 1 is increased from £80/te to £150/te the payback time increases to 2.1 years
but overall the economics are still promising. Therefore, there is flexibility in the option 1 model to cope with increased
feed prices.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
36
6
Conclusions
The main conclusions from the project are:
 Post industrial carpet can be processed into a product with good physical properties which has potential for use in
a range of applications including injection moulding;
 Post consumer carpet, consisting of entirely PP fibres, can be recycled into a product with good physical
properties making it suitable for use in medium to low grade applications, for example injection moulded plant
pots or buckets. The processing stages required to achieve the product are straight forward and involve size
reduction, screening and extrusion;
 Should a carpet recycling plant be of commercial interest further work would be required to select the correct
equipment for each of the processing stages;
 However, a critical factor to the success and quality of the extruded polymer is the correct identification of all
polymer fibres within the carpet. Carpets which contain polymers other than PP, for example nylon or PET,
produce a granulated material which cannot be extruded. It is expected that carpets which contain mixed
polymer blends are more likely to be of woven than tufted construction. The probable end market for mixed
polymer carpets remains equestrian surface applications; and
 The economics of the recycling process look promising and the assessment considered two possible processing
scenarios of which the option of buying pre-sorted whole carpets was favourable over pre-sorted and size
reduced carpets. The payback period of the first option (buying pre-sorted whole carpets) was just over a
year; whereas the payback for the second option (buying pre-sorted and size reduced carpets) was 17 years.
In conclusion the project has proved that a good quality polymer pellet can be produced from post consumer carpets
made entirely of PP, if all of the carpet fibres are correctly identified.
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
37
Appendices
Appendix 1 - Carpet Recycling UK ‘Tufted PP
carpet waste arising in NW’, 2009
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
38
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
39
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
40
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
41
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
42
Axion Consulting Ltd
Tudor House, Meadway,
Bramhall, Cheshire
SK7 2DG
Tel: +44 161 426 7731
Fax: +44 161 426 7732
info@axionconsulting.co.uk
www.axionconsulting.co.uk
Project Name: Envirolink WPC0102 PP recovery from post consumer carpets
Date: December 2009
43