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Recycling polypropylene carpets
In association with Carpet Recycling UK
Funded by Envirolink Northwest
Jane Gardner
Presentation Summary
• Project aims
• Types of carpet
• Current recycling routes
• Demonstration trial results
• Economic assessment
• Project conclusions
Project aims
• To develop a process for recycling polypropylene carpets
• To assess commercial viability of the process
UK Carpet sustainability
• Over half a million tonnes/year of carpet enters the UK waste stream
• Recycling rate currently less than 2%
• Carpets have high carbon footprint due to use of virgin materials – big sustainability gain if recycled
Carpet materials
• Polymers:– Polypropylene (PP);– Polyester/Polyethylene terephthalate (PET);– Nylon;– Chalk-filled elastomers;
• Natural fibres:– Wool; and– Hessian/Jute.
Types of carpet - woven
• Made by weaving the carpet pile into warp fibres with a loom
http://www.armelcarpet.com/images/WovenDiag.gif
• Warp fibres can be polyester or PP, whilst the pile tends to be PP
Types of carpet - tufted
• Pile fibres attached to a backing layer
http://www.fine-flooring.com/TuftedDiagA.gif
• Pile fibres - wool or PP • Elastomer compound
bonds fibres to the backing layer
• Second backing layer – made from hessian or manmade fibre such as PP
Carpet recycling initiatives
America:
• CARE – Carpet America Recovery Effort – founded 2002
Europe – late 1990’s:
• RECAM - Recovery of Carpet Materials
• CRE - Carpet Recycling Europe
• Polyamid 2000 in Germany
UK – late 2000’s:
• Greenback Recycling
• Reeds Carpets – exhibition/temporary floors
Existing end markets• Typically low value• Equestrian surfaces – additive to sand based all
weather surfaces• Plastic cannot be
recovered once used as equestrian surface
• Other applications:• Horticultural
market
http://www.equestriansurfaces.co.uk/aboutus.html
Axion recycling trials
• NIR ID sorting
• Size reduction
• Screening
• Extrusion
Size reduction• Granulation
– 15mm screen
• Alternative options:– Shearing– Shredding
Granulated PP carpet
Screen to remove dust, fines
• High energy flip-flop screen
• 12x12mm deck
• Alternative technique– dry cleaning
Screening results
• Oversized fraction cleaner and less dusty than feed
• High yield loss - due to screen size of granulator (15mm) relative to flip-flop (12mm)
• For 12mm flip-flop - granulator needs to be 20-25mm
• For 15mm granulator screen - flip-flop needs to be 6-8mm
Target fraction Non-target fraction Losses
Oversized Undersized -
38% 59% 3%
Lab scale extrusion
• Sorted PP carpet samples:
– Post industrial
– Post consumer
• Material prepared for extrusion by partial melting then granulation
Extrusion problems
• Initial batch of carpets could not be extruded
• Presence of un-melted fibres made from different polymers – nylon and PET
• Problem due to different types of carpet – woven and tufted
• Second batch of tufted carpet processed successfully
Moulded polymer
• Post industrial – injection moulding applications
• Post consumer – lower grade injection moulding, for example plant pots and buckets
Physical propertiesPhysical properties
testUnits
Post industrial sample
Post consumer sample
MFI (at 230°C, 2.16kg) 6 52
Tensile Mpa 22 23
Elong @ Yield % 7.3 10.1
Elong @ Break % 35.1 28.8
Density g/cm3 1.15 1.023
Ash % 17 10
Commercial assessment
• Feed stock in Northwest - estimated at over 6,000 tonnes per annum meeting specification of:– Tufted construction;– Positively identified PP pile and backing
fibres;– Dry and with no heavy contamination;– Suitable for manual handling.
Overall recycling scheme
Processing option 1
De-baling stage
Size reduction stage
Screening stage
Yield = 80%
Extrusion stage
Yield = 97%
5000 te/year ofBaled sorted
tufted PP carpet
Cost £80/te
5000 te 4000 te3880 te of PP pelletSell for £500/te
Waste to landfill1120 te
Disposal cost £60/te
1000 te
5000 te
Power costStage operating 8 hours,
5 days a week
Power cost Stage operating 8 hours,
5 days a week
Power cost Stage operating 24
hours, 5 days a week
120 te
Power costStage operating 8 hours,
5 days a week
Processing option 2
5000 te/year ofSorted and size
reduced tufted PP carpet
Cost £250/te
Screening stage
Yield = 80%
Extrusion stage
Yield = 97%
4000 te 3880 te of PP pelletSell for £500/te
Waste to landfill1220 te
Disposal cost £60/te
1000 te
Power cost Stage operating 8 hours,
5 days a week
Power cost Stage operating 24 hours,
5 days a week
120 te
Payback calculationOption 1 Option 2
Plant capacity tpa 7500 7500
Capital costs £ £1,000,000 £800,000
Power £/yr £266,000 £254,800
Labour £/yr £277,000 £241,000
Others £/yr £125,000 £109,000
Total operating costs
£/yr £668,000 £604,800
Feed costs £/yr £400,000 £1,250,000
Disposal £/yr £38,100 £38,100
Revenue £/yr £1,940,000 £1,940,000
Margin £/yr £833,900 £47,100
Payback Years 1.2 17.0
Technical conclusions• Straight forward processing route:
– Rigorous PP identification and sorting
– Size reduction
– Screening
– Extrusion
• Finished PP:
– Good physical properties,
– Suitable for use in medium to low grade applications, Eg injection moulded plant pots
Commercial conclusions
• Critical success factor - correct identification of all polymer fibres within the carpet
• Economics of the recycling process are promising
• Next step: Commercial scale testing
Axion Consulting
Tudor House
Meadway
Bramhall
SK2 2DG
0161 426 7731