Recycling of mixed post consumer films. NEXTEK Ltd - What we do & key areas of expertise

Transcription

1 Recycling of mixed post consumer films Edward Kosior Nextek Limited The recovery of flexible Plastics Packaging Roundtable Presentations - SPA 24 th (Sydney) and 26 th (Melbourne) of October, 2012 Copyright Nextek Limited 2012 NEXTEK Ltd - What we do & key areas of expertise Technologies for material separation and recycling into high value products Recycling of post consumer plastics, laminates and films Recycling process design and optimisation of recycling plants Expertise in market development for recycled materials Developing value added products from complex plastic wastes Research and development of novel materials and processes including plastics and bioplastics Successfully completed extensive and ground breaking projects for governments and major commercial organisations in the EU, UK, Middle East, Canada and Australia/NZ More than 30 major projects for UK Government agencies in collaboration with scientific centres of excellence in the UK and Europe Copyright Nextek Limited 2012 Resource Recycling and Resource Innovation 1

2 Nextek Limited Creating Sustainable Solutions in Polymers & Recycling Examples of our work Development of PET HDPE recycling plant for Closed Loop Recycling in London, UK (2005) Large Scale Demonstration of Viability of Recycled PET (rpet) in Retail Packaging (2005) Large Scale Demonstration trial of recycled HDPE into Milk Bottles (2006) Development of light weight compostable packaging for Supermarkets (2007) Household Mixed Plastic Packaging Sorting Project ( ) Commercial Scale Mixed Plastics Recycling Trial (2008) Development of NIR Detectable Black Plastics (2010) Recycling of Commingled Post-Consumer Films (2010) Design of a PET and HDPE food grade recycling plant in Australia ( ) Development of a Food Grade Recycling Process for Post-Consumer PP (2011) 3 Copyright Nextek Limited 2012 Recycling of mixed post consumer films Problems with recycling mixed plastic films Case studies in recycling mixed films Automatic NIR Sorting of films New Wet cleaning and thermal drying systems New dry cleaning systems for films Devolatilisation of films with vacuum extrusion Multi layer film technologies Properties and Applications for recycled film resins 2

3 Composition of Mixed Films MRF waste film (± 0/t) and Black Bag waste (- 75/t) film Analysis of MRF Residual Film Source Film from MSW black bag Analysis Moisture 8% Contam 5% HDPE 16% Moisture 10% Contam 10% HDPE 12% Multi 8% Multi 15% PP 15% LDPE 48% PP 18% LDPE 35% Problems with recycling mixed plastic films Polyethylene (LD+HD) content is typically 45%-65% PP content is 15% - 18% Multi Layer is 8% -15% Contaminants are 5% -10% (paper, rigid plastics, metals) Moisture is 8% -10% Yields will be low - typically 50% at best - lots of waste Throughputs rates low due to low bulk density Multilayer and PP content needs to be minimised Contaminants are stuck to film (paper, organics) Strong odour to recovered films and pellets Moisture and volatiles need to be removed energy cost 3

4 Case study 1 Processing of Mixed Plastic Film ex MRF First trials with mixed plastics required hand sorting, shredding and washing. Processing back into Film Metallised film & obvious multi layer ejected Significant levels of heavily printed film causing volatile emissions during extrusion. PE washed flake processed to pellet was usable at up to 30% with LLDPE Wash waste Lab evaluation 4

5 Re- Extrusion helped to reduce volatiles Double extrusion assisted in volatile removal allowing film blowing Refuse Sacks - 30% Mixed Plastic Film 5

6 Film to Film limitations Original trial results were encouraging, but showed severe limitations at use rates >30% Further R&D trials were needed to improve quality and economic viability Sorting and processing of PE films Separation of PE films from other polymers Re-processing of mixed films -Case studies RELUX UMWELT PCR and other films Reoplast Agricultural and PCR films 6

7 PE Film separation Technologies Separation of PE films based on density using sink float in centrifuges e.g. Flottweg Sorticanter operating at 1500 G forces Limitations: PP still in; loss of mineralfilled PE film; NIR positive identification Can give positive PE fraction of 95% purity works on sizes mm Removes PP and multi layer Will retain filled PE Automatic NIR sorting of mixed films 7

8 Advanced Film Processing Investigation of mixed films Relux Germany and other extrusion processes examine hand & automating sorting address the problem of removal of volatiles Film Sorting at Relux Umwelt NIR sort & agglomeration at Relux Germany Shredded film 120 mm strips NIR sorting of shredded film on 800 wide belt 8

9 Shredding to 60 mm, washing (Herbold), 20mm shred sink float, dry, agglomerate, extrude and filter 135 mmtse; 3 vents; 200um filter,2 tphr High Performance devolatilisation RELUX EXTRICOM MAS GNEUSS EREMA 9

10 Successful recovery of materials Commercial throughputs achieved with excellent odour removal, loss of dark coloration & devolatilisation 100% recycled film Processing Mixed Films with Dry Cleaning Mixed PC films from MRF- Trial in Czech Blended with Agricultural film 10

11 Plant Layout- Dry Clean and extrude to pellet Dirt removal Extruder and melt filter Dry Cleaner Input and Shredder Household and agricultural films blended Debaled film is loaded to Shredder Films mixed on the input conveyor with some sorting Shredded films 11

12 Double step DRD dry cleaner Shredded film is metered into first chamber Fluidised with air; abraded by rotors and flakes Screens remove fines at each DRD unit Dry Cleaning of Film The DRD by MAS combines a cleaning centrifuge and thermal drying in one machine The material rotates in a cylindrical chamber suspended in hot air. The turbulent airflow ensures maximum drying effect At the same time impurities such as sand and soil are separated via screens 12

13 Removal of fines and contamination The dry cleaner both dries and abrades the film in the chamber for a controlled time Initial in-feed final flake Extrusion, Melt filtration, cascade de-gassing, Pelletising 13

14 Engineering Stress (MPa) 10/29/2012 Material properties of recovered films Engineering Strain Film Dry Cleaning and Extrusion Economics 14

15 New developments in wet washing and drying of film Sorema have developed a new concept for low temperature drying to follow the sequence of; wet-grinding centrifugal separation and cleaning intense washing sink float separation mechanical drying. Low energy drying system- Sorema Large volumes of air at low temperatures provide drying at low energy cost 15

16 Optimised system for the recycling of mixed films De-baling, Trommel/ballistic separator Large screen shredder (200mm) NIR sorter into PE fraction Dry Grinder (30 mm) Dry Cleaner Vacuum Devolatilisation Extrusion Wet Grinder Washing and sink/float separation Low Temperature drying Multi-layer films recycling Key issue is to understand and control the composition by blending Sorting by Sink /Float or NIR needed to avoid degradation of PVC and PVdC causing discolouration. PVdC laminates can be separated into layers of PE and PVdC by sink float Barrier films (Nylon, PET,EVOH) difficult to separate- best to melt and disperse at high temp with compatibiliser Blending of miscible systems possible Ionomer (Surlyn) and Nylons and EVOH films to make uniform mono-material film Use of coated fillers to aid dispersion and act as volatile absorbers Clean? film input Degraded PVdC contamination 16

17 Markets for recovered PE film materials Limitations: Color and odor and thickness for grades Sales Product can be Flake, Agglomerate and Pellet Film for refuse sacks 100% post user film Film for building products-damp-proof membrane and protective sheeting- 100% post user film Sheet- Underground Utility Protection- for electrical cables, gas, pipes -100% Materials Handling - slip sheets 100% Fencing and Hoardings- construction sites -100% Stock and animal housing partitions 100% Plastic Lumber for decking, marine, posts, ground protection, civic furniture Films Recycling: Summary Separation of PE achieved by NIR or specific gravity but using both is best Extrusion devolatilisation systems can remove odour and improve processability Dry cleaning of films can be effective and economic New efficient drying systems for wet cleaning Blending of household films with agricultural film can speed production and make useful products Multilayer film recycling requires control of composition and processing Sizeable markets exist for films, sheet and board 17