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

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Presentation on theme: "Steve Pickering School of Mechanical, Materials and Manufacturing Engineering Routes to Recycling or Disposal of Thermoset Composites."— Presentation transcript:

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

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

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: CaCO3 1.8 MJ/kg (+800 C) ATH 1.0 MJ/kg ‘Cleaner than coal’ Bulky ash remaining

12 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 Thermal Processing Combustion with energy and material recovery

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 Recovered Fillers Heat Recovery Recovered 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 1 mm 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 fibreMoulding - virgin glass fibre Moulding - 50% recycled glass fibreMoulding - 50% recycled glass fibre Moulding Compounds Only effect is 25% reduction in impact strength no change to processing conditions demonstrator components produced

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

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

21 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

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

26 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: CO 2 & CO (75%) + H 2, CH 4 ……. 40% Oils hydrocarbons, styrene (26%) ……. 15% Waxes phthalic anhydride (96%) ….. 39% Solids glass fibre & fillers (CaCO 3 ), 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 Energy use for recovery process is 10% of virgin fibre production 40% to 45% energy reduction observed for recovered fibre composites Fluidised Bed Process


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