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

info@axionconsulting.co.uk