Recycling polypropylene carpets In association with Carpet Recycling UK Funded by Envirolink...
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Transcript of Recycling polypropylene carpets In association with Carpet Recycling UK Funded by Envirolink...
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