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Routes to Recycling or Disposal of Thermoset Composites

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Presentation on theme: "Routes to Recycling or Disposal of Thermoset Composites"— Presentation transcript:

1 Routes to Recycling or Disposal of Thermoset Composites
Steve Pickering School of Mechanical, Materials and Manufacturing Engineering

2 Presentation Outline Need to Recycle
Problems in recycling thermoset composites Recycling/Disposal Processes mechanical recycling thermal processing Future Prospects

3 Need to Recycle Pressure from legislation EU Directives Landfill
End-of-Life Vehicles Waste Electrical and Electronic Equipment Construction and Demolition Waste

4 Does not measure recycling quality (environmental benefit)
Recycling Heirarchy Prevent waste Reuse product Recycle material Incineration with material and energy recovery with energy recovery without recovery Landfill Does not measure recycling quality (environmental benefit)

5 Problems in Recycling Thermoset Composites
Technical Problems Thermosetting polymers can’t be remoulded Long fibres Mixtures of materials (different compositions) Contamination Costs Collection and Separation

6 Recycling Processes for Thermoset Composites
Mechanical Recycling (comminution) Thermal Processes Pyrolysis/ Gasification Powdered fillers Fibrous products (potential reinforcement) Combustion with energy recovery (and material utilisation) Fluidised bed process Chemical products, fibres and fillers Clean fibres and fillers with energy recovery

7 Mechanical Recycling Size reduction Coarse primary crushing
Hammer milling followed by grading to give: Powder Coarser fractions (reinforcement rich) All scrap material is contained in recyclate (incl. different polymers, contamination, paint….)

8 Mechanical Recycling Recycling into new composites
Powdered recyclate useful as a filler (up to 25% incorporated in new composite) Coarser recyclate has reinforcement properties (up to 50% substitution of glass fibre) Several companies have been founded to commercialise recycling – ERCOM (Germany), Phoenix Fiberglass (Canada)

9 Mechanical Recycling Recycling into other products
Compounding with thermoplastics Production of reinforcement with recyclate core to allow resin flow during impregnation Using recyclate to provide damping (noise insulation) Alternative to wood fibre Asphalt

10 Thermal Processing Combustion with Energy and Material Recovery
Calorific value of thermosetting resins ~ 30 MJ/kg Co-combustion with municipal waste in mass burn incinerators Co-combustion in cement kilns Co-combustion with coal in fluidised bed

11 Thermal Processing Combustion with energy recovery
Calorific value depends on inorganic content ( MJ/kg) Filler effects: CaCO MJ/kg (+800 C) ATH 1.0 MJ/kg ‘Cleaner than coal’ Bulky ash remaining

12 Thermal Processing Combustion with energy and material recovery
Cement manufacture energy recovery from polymer glass and fillers combine usefully with cement minerals fuel substitution limited to <10% by boron in E-glass Potential savings <£20/tonne of GRP used

13 Thermal Processing Combustion with energy and material recovery
Fluidised Bed Coal Combustion (Limestone filled composites) energy recovery from polymer limestone filler absorbs oxides of sulphur from coal commercial trial undertaken

14 Thermal Processing – Fluidised Bed Process
Cyclone Air Inlet Electric Pre-heaters Fibre Scrap CFRP Recovered Fluidised Bed Air distributor plate 300 mm Afterburner Clean flue gas To energy recovery Fan

15 Fluidised Bed Processing
Materials and Energy Recovery Fluidised Bed Scrap FRP Separation of fibres and fillers Recovered Fibres Fillers Heat Recovery Energy Clean Flue Gas Secondary Combustion Chamber Fibres and fillers carried in gas flow

16 Fluidised Bed Operation
Temperature: 450 to 550 deg C Fluidising air velocity: up to 1.3 m/s Fluidising medium: silica sand 1mm Able to process contaminated and mixed composites eg: double skinned, foam cored, painted automotive components with metal inserts

17 Recovered Glass Fibres
Properties Strength: reduced by 50% (at 450 C) Stiffness: unchanged Purity: 80% Fibre length: 3 to 5 mm (wt)

18 Reuse of Recycled Glass Fibre Moulding Compounds
Moulding - virgin glass fibre Moulding Compounds Only effect is 25% reduction in impact strength no change to processing conditions demonstrator components produced Moulding - 50% recycled glass fibre

19 Outline Process Economics Glass Fibre Recycling
Commercial Plant Schematic (5000 tonnes/year)

20 Outline Process Economics Glass Fibre Recycling
5,000 tons/year Capital £3.75million Annual costs: £1.6 million Annual Income: £1.3 million Breakeven throughput: 10,000 tons/year

21 Fluidised Bed Process Clean flue gas Scrap CFRP Cyclone Afterburner
Air Inlet Electric Pre-heaters Fibre Scrap CFRP Recovered Fluidised Bed Air distributor plate 300 mm Afterburner Clean flue gas To energy recovery Fan

22 Carbon Fibre Properties
Tensile strength reduced by 25% Little change in modulus No oxidation of carbon fibres

23 Carbon Fibre Properties Fibre Quality
Fibre surface quality similar to virgin fibre Clean fibres produced ~200mm 100mm 100m

24 Recovered Fibre Composite
Fibres made into polycarbonate composite Strength Stiffness

25 Thermal Processing Reactor Pyrolysis Process Condenser Scrap feed
Hot gases Solid and Liquid Hydrocarbon Products Combustible Gases to heat reactor Solid Products (fibres, fillers, char) Pyrolysis Process

26 Thermal Processing Pyrolysis Processes
Heating composite (400 – 800°C) in absence of air to give hydrocarbon products – gases and liquids fibres Some char contamination on fibres Hydrocarbon products potential for use as fuels or chemical feedstock Low temperature (200°C) catalytic pyrolysis for carbon fibre Gasification – limited oxygen – no char, fuel gases evolved

27 Thermal Processing Products from Pyrolysis (450°C)
Polyester Composite (30% glass fibre, 7% filler, 63% UP resin) 6% Gases: CO2 & CO (75%) + H2, CH4 ……. 40% Oils hydrocarbons, styrene (26%)……. 15% Waxes phthalic anhydride (96%)….. 39% Solids glass fibre & fillers (CaCO3), char (16%)

28 What is best Recycling Route??
Established hierarchy and ELV Directive favour mechanical recycling techniques – but are these the best environmentally?? Detailed Life Cycle Analysis needed to identify environmental impact Recent project in Sweden (VAMP18) has considered best environmental and cost options for recycling a range of composites

29 Prospects for Commercial Success?
ERCOM and Phoenix – viable levels of operation not achieved Recyclates too expensive to compete in available markets Need to develop higher grade recyclates for more valuable markets Legislation and avoidance of landfill are new driving forces

30 Value in Scrap Composites
Energy value of polymer £ 30/tonne Value of polymer pyrolysis products Maleic Anhydride, Bisphenol A £1,000/tonne Value of filler £ 30/tonne Value of glass fibre £1,000/tonne Value of carbon fibre £10,000/tonne

31 New Initiative EuCIA (GPRMC) initiative
ECRC (European Composites Recycling Concept) Scheme to fund recycling to meet EU Directives A guarantee that composites will be recycled

32 Conclusions A range of technologies is under development
material recycling thermal processing Key barriers to commercial success are markets at right cost Need for environmental analysis to identify best options Future legislation is driving industry initiatives

33 Recycled Carbon Fibre Life Cycle Analysis
Fluidised Bed Process Recycled Carbon Fibre Life Cycle Analysis Energy use for recovery process is 10% of virgin fibre production 40% to 45% energy reduction observed for recovered fibre composites

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