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Pyrolysis and Detoxification of Waste Electrical and Electronic Equipment (WEEE) for Feedstock Recycling
KTH, School of Industrial Engineering and Management (ITM). (Unit of Process)ORCID iD: 0000-0002-9949-6274
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The trends in waste electrical and electronic equipment (WEEE) generation shows that their volume constantly increases, while the current waste management technologies have proven to be insufficient in order to meet the strict criteria and the new legislations of the European Union. Pyrolysis and thermal treatment in general could be a valuable solution for closing the loop of materials and could contribute to the energy demands of modern society.

Pyrolysis as a process and combination of other pre-treatment techniques was investigated with a focus on energy production, metal separation and feedstock recycling. In this work, several fractions of real WEEE have been tested based on the process requirements and the focus of each individual study.

Firstly, the investigation was focused on the primary products of the process, revealing most of the environmental pollutants as well as the valuable monomers that can enhance feedstock recycling. A correlation of the process’ final temperature with the evolution of the major products was performed. Moreover, a conceptual reaction mechanism of Bisphenol A decomposition was suggested based on the process products.

Then, a reduction of the bromine content of the initial WEEE fraction was achieved by solvent extraction pre-treatment. Isopropanol and toluene were tested as solvents capable of removing one of the main flame retardants at WEEE fractions, Tetrabromobisphenol A. The results indicate that the reduction of bromine was successfully performed even at ~37%. This result was further confirmed by the reduction or total removal of brominated species in the pyrolysis products. The toluene seems to be a valuable option for the pre-treatment, since it can be provided by the pyrolysis process itself, making the entire treatment more sustainable and in accordance with the concept of circular economy.

Density separators used in the sorting of WEEE materials usually produced high moisture content fractions. As soon as those fractions follow thermal treatment, the moisture will eventually become steam, which influences the process. Therefore, WEEE materials were pyrolysed in nitrogen and steam atmospheres and their decomposition was evaluated. Steam had a negative impact on the products, since several high molecular weight products were detected, revealing that steam limits secondary cracking reactions. Additionally, the results show that the presence of steam complicates the separation of oils and favours the migration of antimony to the gas phase. Therefore, a drying step before using pyrolysis for this fraction is necessary.

Low temperature pyrolysis was also investigated for making the WEEE more fragile to enhance metal separation from the carbonised solid residue while the fate of bromine was also monitored. The results indicate that the separation is possible at low temperatures for minimising the energy consumption of the process but it should be at least 40 ° higher than the onset temperature of the selected material. The separation was also evaluated with fractionation of the solid residue, revealing that the produced bromine-free solid carbonised material can be further utilised for energy production.

Finally, the entire process was tested in a continuous screw reactor for overall process evaluation. The results indicate that the liquid products of pyrolysis can be used for feedstock recycling, producing necessary organic compounds that can be used for manufacturing new plastics or can be used as liquid fuel. The brominated compounds tend to migrate to the gas phase, as the temperature of the process increases, making the recycling of metals from the solid residue easier. The process in general can be self-sustained since the energy needed for the system to heat up can be covered from its gas production.

Abstract [sv]

Baserat på de nuvarande trenderna inom avfallssektorn för elektrisk och elektronisk avfall (WEEE) behöver den nuvarande avfallshanteringen förbättras för att godkännas av nya strikare lagstiftningarna i Europeiska Unionen. Pyrolys och termisk behandling i allmänhet kan vara värdefulla tillvägagångssätt för att sluta materialkedjan för en cirkulär ekonomi samt bidra till energibehovet i det moderna samhället.

Pyrolys i kombination med andra förbehandlingstekniker har undersökts med fokus på material- och energiåtervinning samt separation av metaller. I avhandlingen har olika fraktioner av WEEE undersökts baserat på processkrav och fokuset i enskilda studier.

Initialt var den experimentella undersökningen inriktad på processens primära produkter, vilket påvisade förekomsten av flertalet miljöföroreningarna liksom värdefulla monomerer för framida materialåtervinning. Detta arbete utgjordes av en korrelativ studie mellan processens behandlingstemperatur och framställningen av de huvudsakliga produkterna. Dessutom skapades en konceptuell reaktionsmekanism för nedbrytning av bisfenol A baserat på processprodukterna.

En annan studie reducerade bromhalten i WEEE genom förbehandling i form av lösningsmedelsextraktion. Isopropanol och toluen undersöktes utifrån deras förmåga att extrahera en av de huvudsakliga flamskyddsmedlen som finns i WEEE, dvs tetrabrombisfenol A. Projektet resultatvisar att bromhalten reducerades med ca 37 %. Detta resultat bekräftades också vid efterföljande pyrolysexperiment genom reduktion eller omätbara halter av bromerade arter i pyrolysprodukterna. Toluen tycks därför vara ett lovande alternativ för förbehandlingen och kan dessutom tillhandahållas av pyrolysprocessen själv genom att utgöra en huvudsaklig komponent i framställd pyrolysolja, vilket bidrar till en mer hållbar behandlingsmetod.

Densitetsavskiljare som används inom hanteringen av WEEE resulterar ofta i fraktioner med hög fukthalt. När sådana fraktioner utsätts för termisk behandling kommer således fukten att omvandlas till vattenånga, vilket påverkar processen. Därför gjordes experimentella försök där WEEE pyrolyserades i kvävgas och vattenånga följt av utvärdering av materialets nedbrytning i respektive miljö. Vattenånga hade negativ påverkan på pyrolysprodukterna genom ökade molekylvikter, vilket visar att vattenånga begränsar sekundära krackningsreaktioner. Dessutom visar resultaten att vattenånga komplicerar separationen av bildade oljor samt gynnar migrering av antimon från kolrest till gasfasen. Därmed anses ett torkningssteg före pyrolys av WEEE absolut nödvändigt.

Pyrolys vid lägre temperaturer undersöktes för att studera WEEEs bräcklighet vid olika temperaturer för att förbättra metallavskiljningen från den organiska fasta restprodukten från pyrolys samt att identifiera broms fördelning bland produkterna. Resultaten indikerar att separation är möjlig vid låga temperaturer för att minimera processens energiförbrukning men minst 40 °C högre än temperaturen då materialet termiskt börjar sönderdelas. Separationen utvärderades också med fraktionering av den fasta återstoden, vilket visade att det framställda bromfria fasta produkten kan användas ytterligare för energiåtervinning.

Slutligen testades hela processen i en kontinuerlig skruvreaktor för övergripande processutvärdering. Resultaten indikerar att de flytande produkterna från pyrolys kan användas för materialåtervinning, vilket därmed utgör en råvara avorganiska föreningar som kan användas för att tillverka ny plast eller exempelvis flytande bränsle. De bromerade föreningarna i WEEE tenderar att migrera till gasfasen. Dessutom blir separationen av metaller enklare med en ökad temperatur. Processen i allmänhet kan vara självförsörjande på energi då de bildade pyrolysgaserna innehåller tillräckligt mycket energi för att värma systemet vid kontinuerlig användning.

Abstract [el]

Με τους ρυθμούς ανάπτυξη της τεχνολογίας σήμερα, τα Απόβλητα ειδών Ηλεκτρικού & Ηλεκτρονικού Εξοπλισμού (ΑHHE) η waste electrical and electronic equipment (WEEE) συνεχώς αυξάνονται ενώ οι τεχνολογίες διαχείρισης και ανάκτησης υλικών πρέπει να βελτιώνονται προκειμένου να συναντήσουν τα αυστηρά κριτήρια που έχει θέσει η ευρωπαϊκή νομοθεσία. Η πυρόλυση και γενικά οι θερμοχημικές διεργασίες θα μπορούσαν να αποτελέσουν μια βιώσιμη λύση για περαιτέρω ανάκτηση των υλικών αλλά και για αξιοποίησης του ενεργειακού τους περιεχομένου.

Η πυρόλυσή αλλά και άλλες προκατεργασίες έχουν μελετηθεί πειραματικά με στόχο την παραγωγή ενέργειας, τον διαχωρισμό των μετάλλων και την ανάκτηση του οργανικού περιεχομένου των ΑΗΗΕ. Μερικά από τα πιο σημαντικά κλάσματα των ΑΗΗΕ έχουν εξεταστεί με βάση τους περιορισμούς που μπορεί να προκαλέσουν στην διεργασία.

Αρχικά, η έρευνα επικεντρώθηκε στα πρωτογενή προϊόντα της πυρόλυσης, αποκαλύπτοντας τους περιβαλλοντικούς ρύπους καθώς και τα παραγόμενα μονομερή που μπορούν να χρησιμοποιηθούν για την ανακύκλωση πρώτων υλών. Έγινε συσχέτιση της τελικής θερμοκρασίας της διεργασίας με την παραγωγή των κυριότερων προϊόντων. Επιπλέον, προτάθηκε ένας μηχανισμός αντίδρασης της αποσύνθεσης της δισφαινόλης Α με βάση τα προϊόντα της διεργασίας.

Στη συνέχεια, η μείωση της περιεκτικότητας σε βρώμιο του αρχικού κλάσματος ΑΗΕΕ επιτεύχθηκε με προκατεργασία εκχύλισης με διαλύτη. Η ισοπροπανόλη και το τολουόλιο δοκιμάστηκαν ως διαλύτες ικανές να απομακρύνουν ένα από τα κύρια επιβραδυντικά φλόγας σε κλάσματα WEEE, την Τετραβρωμο-δισφαινόλη Α. Τα αποτελέσματα δείχνουν ότι η μείωση του βρωμίου διεξήχθη επιτυχώς ακόμη και στο ~ 37%. Αυτό το αποτέλεσμα επιβεβαιώθηκε περαιτέρω από τη μείωση ή την ολική απομάκρυνση βρωμιωμένων ειδών στα προϊόντα πυρόλυσης. Το τολουόλιο φαίνεται να αποτελεί την πιο πολύτιμη επιλογή για την προεπεξεργασία, δεδομένου ότι μπορεί να παρασχεθεί από την ίδια τη διαδικασία πυρόλυσης, καθιστώντας όλη την επεξεργασία βιώσιμη.

Η υψηλή περιεκτικότητα σε υγρασία που προέρχεται από διαχωριστές πυκνότητας διερευνήθηκε επίσης ως ένας άλλος σημαντικός περιοριστικός παράγοντας της ανακύκλωσης των ΑΗΗΕ μέσω της πυρόλυσης. Τα ΑΗΗΕ πυρολύθηκαν σε ατμόσφαιρα αζώτου και ατμού και αξιολογήθηκε η αποσύνθεση τους. Ο ατμός έδειξε αρνητική επίδραση στα προϊόντα, καθώς ανιχνεύθηκαν αρκετά προϊόντα υψηλού μοριακού βάρους, αποκαλύπτοντας ότι ο ατμός περιόριζε τις δευτερογενείς αντιδράσεις πυρόλυσης. Επιπλέον, τα αποτελέσματα δείχνουν ότι η παρουσία ατμού περιπλέκει τον διαχωρισμό των ελαίων και ευνοεί τη μετανάστευση του αντιμονίου στην αέρια φάση. Επομένως, ένα στάδιο ξήρανσης πριν από τη χρήση πυρόλυσης για αυτό το κλάσμα είναι απολύτως απαραίτητο.

Πυρόλυση χαμηλής θερμοκρασίας διερευνήθηκε επίσης για να γίνει το ΑΗΗΕ πιο εύθραυστο για την βελτίωση του διαχωρισμού μετάλλων από το οργανικό ανθρακούχο στερεό υπόλειμμα. Τα αποτελέσματα δείχνουν ότι ο διαχωρισμός είναι εφικτός σε χαμηλές θερμοκρασίες για ελαχιστοποίηση της ενεργειακής κατανάλωσης της διεργασίας αλλά τουλάχιστον κατά 40° υψηλότερη από τη θερμοκρασία εκκίνησης του επιλεγμένου υλικού. Ο διαχωρισμός αξιολογήθηκε επίσης με κλασμάτωση του στερεού υπολείμματος, αποκαλύπτοντας ότι το παραγόμενο χωρίς βρώμιο στερεό ανθρακούχο υλικό μπορεί περαιτέρω να χρησιμοποιηθεί για παραγωγή ενέργειας.

Τέλος, ολόκληρη η διεργασία δοκιμάστηκε σε συνεχή κυλινδικού περιστρεφόμενου αντιδραστήρα για συνολική αξιολόγηση της διαδικασίας. Τα αποτελέσματα δείχνουν ότι τα υγρά προϊόντα πυρόλυσης μπορούν να χρησιμοποιηθούν για ανακύκλωση πρώτων υλών, δημιουργώντας τις απαραίτητες οργανικές ενώσεις που μπορούν να χρησιμοποιηθούν για την κατασκευή νέων πλαστικών ή μπορούν να χρησιμοποιηθούν ως υγρό καύσιμο. Οι βρωμιωμένες ενώσεις τείνουν να μεταναστεύουν στην αέρια φάση, καθώς η θερμοκρασία της μεθόδου αυξάνεται καθιστώντας ευκολότερη την ανακύκλωση μετάλλων από το στερεό υπόλειμμα. Η διαδικασία γενικά μπορεί να είναι αυτοσυντηρούμενη αφού η ενέργεια που απαιτείται για να θερμανθεί το σύστημα μπορεί να καλυφθεί από την παραγωγή του αερίου επεξεργασίας.

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH Royal Institute of Technology, 2018. , p. 52
Series
TRITA-ITM-AVL ; 2018:56
Keywords [en]
Pyrolysis, WEEE, solvent extraction, brominated flame retardants, Tetrabromobisphenol A, Auger reactor
Keywords [el]
Πυρόλυση, ΑΗΗΕ, εκχύλιση με διαλύτη, βρωμιωμένα επιβραδυντικά φλόγας, Τετραβρωμοδιφαινόλη Α
Keywords [sv]
Pyrolys, WEEE, lösningsmedelsextraktion, bromerade flamskyddsmedel, tetrabrombisfenol A
National Category
Environmental Management Chemical Process Engineering Polymer Technologies
Research subject
Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-238629ISBN: 978-91-7729-953-0 (print)OAI: oai:DiVA.org:kth-238629DiVA, id: diva2:1261100
Public defence
2018-11-30, Kollegiesalen, Brinellvägen 8, Stockholm, 14:00 (English)
Opponent
Supervisors
Projects
Energi- och materialåtervinning fåm WEEE (36880-1)Pyrolys och dehalogenering av plastbaserat WEEE i skruvreaktor (36880-2)Available from: 2018-11-09 Created: 2018-11-06 Last updated: 2018-11-12Bibliographically approved
List of papers
1. Investigation of the thermal decomposition of printed circuit boards (PCBs) via thermogravimetric analysis (TGA) and analytical pyrolysis (Py-GC/MS)
Open this publication in new window or tab >>Investigation of the thermal decomposition of printed circuit boards (PCBs) via thermogravimetric analysis (TGA) and analytical pyrolysis (Py-GC/MS)
2015 (English)In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 115, p. 337-343Article in journal (Refereed) Published
Abstract [en]

The purpose of this study is to experimentally investigate the pyrolytic behavior of printed circuit boards (PCBs) waste fraction at a temperature range of 400 °C to 900 °C by means of thermogravimetric analysis (TGA) and analytical pyrolysis (Py-GC/MS) was carried out. The experimental results reveal that the chemical composition of the PCBs and the relatively high ash content (=79% w/w) are strongly connected with the high quantity of metals and ceramic materials. The main decomposition of PCBs occurs between 250 °C and 370 °C. The pyrolysis of PCBs showed a varying production of aromatic compounds such as phenol, bromophenol, styrene, methylstyrene, and bisphenol A as well as non-aromatic compounds such as acetone and bromomethane, which are strongly related with the initial chemical composition of PCBs. Moreover, Py-GC/MS revealed that temperature increase favours the production of aromatic hydrocarbons, while the phenol which is the most abundant compound produced, shows an opposite trend, as a result of its further decomposition to simpler products. Furthermore, brominated compounds produced, such as bromomethane and bromophenol, are derived from the flame retardant used during the manufacturing process and in that case the Py-GC/MS showed a slight decrease of brominated compounds with increase in temperature.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
e-Waste, PCBs, Printed circuit boards, Py-GC/MS, Pyrolysis, TGA, Acetone, Aromatic compounds, Aromatic hydrocarbons, Aromatization, Bromine compounds, Ceramic materials, Chemical analysis, Chemical compounds, Cracking (chemical), Decomposition, Phenols, Printed circuits, Styrene, Thermogravimetric analysis, Analytical pyrolysis, Chemical compositions, E-wastes, Manufacturing process, Printed circuit board (PCBs)
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-175080 (URN)10.1016/j.jaap.2015.08.012 (DOI)000362610300038 ()2-s2.0-84942296049 (Scopus ID)
Funder
Swedish Energy Agency, 36880-1
Note

QC 20151211

Available from: 2015-12-11 Created: 2015-10-09 Last updated: 2018-11-06Bibliographically approved
2. Reduction of brominated flame retardants (BFRs) in plastics from waste electrical and electronic equipment (WEEE) by solvent extraction and the influence on their thermal decomposition
Open this publication in new window or tab >>Reduction of brominated flame retardants (BFRs) in plastics from waste electrical and electronic equipment (WEEE) by solvent extraction and the influence on their thermal decomposition
Show others...
(English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456Article in journal (Refereed) In press
Abstract [en]

Consumption of electronics increases due to modern society’s growing needs, which leads to increasing generation of waste electrical and electronic equipment (WEEE). Recycling of WEEE has been a global concern during the last few decades because of the toxic compounds that are produced during recycling. Different recycling techniques have been adapted on a commercial scale in order to overcome this issue, but the recycling of WEEE still lacks the technology to treat different kinds of feedstocks and to maximise the recycling rates. Pyrolysis is an alternative that has not been commercialised yet. One of the challenges for the implementation of this technology is the toxic brominated organic compounds that can be found in the pyrolysis oils.

In this study, tetrabromobisphenol A (TBBPA), one of the major flame retardants, is reduced in three different WEEE fractions through solvent extraction as a treatment prior to pyrolysis. Two solvents have been experimentally investigated: isopropanol and toluene, the latter of which can be derived from pyrolysis oil. The results indicate that TBBPA was extracted during pre-treatment. Moreover, the total bromine content of WEEE material was reduced after the treatment with a maximum reduction of 36.5%. The pyrolysis experiments indicate that reduction of several brominated organic compounds was achieved in almost all the tested cases, and two brominated compounds (2,4,6-tribromophenol and 2,5-Dibromobenzo(b)thiophene) reached complete removal. Also, the thermal decomposition behaviour of the raw samples and the treated was investigated, showing that the reduction of TBBPA influences the decomposition by shifting the starting decomposition temperature.

Keywords
Tetrabromobisphenol A; BFRs; Pyrolysis; Soxhlet; WEEEE; e-waste
National Category
Environmental Management Other Materials Engineering Chemical Engineering
Research subject
Materials Science and Engineering; Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-238628 (URN)10.1016/j.wasman.2018.06.018 (DOI)000477786000017 ()2-s2.0-85048762620 (Scopus ID)
Note

QC 20181107

Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2019-08-20Bibliographically approved
3. Experimental investigation of the influence of reaction atmosphere on the pyrolysis of printed circuit boards
Open this publication in new window or tab >>Experimental investigation of the influence of reaction atmosphere on the pyrolysis of printed circuit boards
2017 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 204, p. 1065-1073Article in journal (Refereed) Published
Abstract [en]

Printed circuit boards (PCB) are one of the most challenging fractions of waste electrical and electronic equipment (WEEE) in terms of recycling due to their complexity and diversity. Pyrolysis seems to be a promising alternative for production of energy carriers from its organic fraction with simultaneous recovery of metals. Reaction atmosphere is among the process parameters that affects the thermal decomposition as well as the products’ formation and distribution. In this study, the decomposition of two different PCB fractions in inert and steam atmospheres has been investigated by means of thermogravimetric analysis (TGA) and lab scale fixed bed reactor experiments. It was found that the decomposition of the tested materials in steam atmosphere starts at lower temperatures and proceeds slower compared to the N2 atmosphere. Moreover, a two-step decomposition has been observed on the PCB sockets fraction due to the fact that high amount of antimony oxide was present, a common additive for improving the flame retardancy, which have been also observed on previous studies (Wu et al., 2014). The presence of steam influence the pyrolysis gas composition and promotes additional vaporisation of antimony as verified by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the liquid fraction has been qualitatively analysed using a GC/MS in order to determine the brominated compounds as well as other compounds that are produced from this process.

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
Keywords
Antimony, Printed circuit boards, Pyrolysis, TGA, Waste electrical and electronic equipment (WEEE), Chemical reactors, Decomposition, Electronic equipment, Electronic Waste, Metal recovery, Oscillators (electronic), Scanning electron microscopy, Thermogravimetric analysis, Timing circuits, X ray diffraction, Brominated compounds, Experimental investigations, Lower temperatures, Powder X ray diffraction, Printed circuit boards (PCB), Process parameters, Reaction atmospheres, Waste electrical and electronic equipment, complexity, PCB, reaction kinetics, recycling, thermal decomposition, X-ray diffraction
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-218890 (URN)10.1016/j.apenergy.2017.04.087 (DOI)000412866500083 ()2-s2.0-85019150889 (Scopus ID)
Note

QC 20180117

Available from: 2018-01-17 Created: 2018-01-17 Last updated: 2019-10-18Bibliographically approved
4. Investigation on the low-temperature pyrolysis of automotive shredder residue (ASR) for energy recovery and metal recycling
Open this publication in new window or tab >>Investigation on the low-temperature pyrolysis of automotive shredder residue (ASR) for energy recovery and metal recycling
2018 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 76, p. 507-515Article in journal (Refereed) Published
Abstract [en]

The automotive shredder residue (ASR) or shredder light fraction (SLF) is the remaining fraction from the metal recovery of end-of-life vehicles (ELVs). While processes for metal recovery from ELVs are well developed, the similar process for ASR remains a challenge. In this work, low-temperature pyrolysis of the ASR fraction was investigated under the assumption that a low temperature and inert environment would enhance the metal recovery, i.e. the metals would not be further oxidised from their original state and the organic material could be separated from the metals in the form of volatiles and char. Pyrolysis experiments were performed in a tube reactor operating at 300, 400 and 500 degrees C. The gas and oil obtained by pyrolysis were analysed by micro-GC (micro-Gas Chromatography) and GC/MS (Gas Chromatography/Mass Spectrometry), respectively. It was found that the gas produced contained a high amount of CO2, limiting the energy recovery from this fraction. The oil consisted of a high concentration of phenolic and aromatic compounds. The solid residue was crushed and fractionated into different particle sizes for further characterization. The pyrolysis temperature of 300 degrees C was found to be insufficient for metal liberation, while the char was easier to crush at tested temperature of 400 and 500 degrees C. The intermediate temperature of 400 degrees C is then suggested for the process to keep the energy consumption low.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Automotive shredder residues (ASR), Pyrolysis, Metal recovery, Thermal treatment, Shredder light fraction (SLF), End-of-life vehicles (ELVs)
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-231730 (URN)10.1016/j.wasman.2018.03.048 (DOI)000435064000050 ()29628362 (PubMedID)2-s2.0-85044935411 (Scopus ID)
Note

QC 20180814

Available from: 2018-08-14 Created: 2018-08-14 Last updated: 2018-11-06Bibliographically approved
5. Experimental investigation of low temperature pyrolysis of printed circuit boards (PCBs) and printed circuit board components (PCB sockets)
Open this publication in new window or tab >>Experimental investigation of low temperature pyrolysis of printed circuit boards (PCBs) and printed circuit board components (PCB sockets)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Printed circuit boards (PCBs) are the heart of all electronics due to their compact size and the broad spectrum of applications but very challenging when their life ends. Recycling of these components is problematic since they consist of different metallic parts packed on plastic compressed cover. The present study focuses on low temperature pyrolysis of PCBs since this process can separate the organic fraction from the inorganics. The latter, enables further separation and purification of the metals which are not oxidized during mild treatment. The low Br content of the resultant char after treatment at 320 oC for 30 min indicates that it could be used as solid fuel if efficient separation from the inorganic part would be performed. Moreover, the liquids obtained by this process can be used for feedstock recycling since the results indicates that toxic bromine containing on the organic compounds has been decreased both by increasing the residence time of pyrolysis process or by increasing the temperature conditions.

Keywords
Pyrolysis, low temperature, pretreatment, metal recycling, hazardous waste, PCBs
National Category
Chemical Engineering Composite Science and Engineering Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-238644 (URN)
Note

QC 20181109

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-09Bibliographically approved
6. Pyrolysis of waste electrical and electronic equipment (WEEE) on a single screw reactor for bromine free oil production
Open this publication in new window or tab >>Pyrolysis of waste electrical and electronic equipment (WEEE) on a single screw reactor for bromine free oil production
(English)Manuscript (preprint) (Other academic)
Abstract [en]

This study focuses on pyrolysis on waste electrical and electronic equipment or WEEE as it is usually referred in the literature. A new auger reactor has been designed and tested with WEEE material. The performance of the reactor as well as the fate of the bromine has been investigated and evaluated in order to be used for designing of industrial process. The mass balance calculations performed for the tested cases of 400, 500 and 600 °C, showed a high gas yield (44%) at the temperature of 600 °C, which can be used to fulfil the process energy needs. At the low temperature of 400 °C the oil production reach its maximum yield, while the bromine content of the oil has also a maximum percentage of 0.5% wt. Several valuable compounds have been detected in the oil composition, which can be used either as fuels or for feedstock recycling.

Keywords
Pyrolysis, Screw reactor, WEEE, BRFs, brominated flame retardants
National Category
Materials Engineering Chemical Engineering Environmental Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-238645 (URN)
Note

QC 20181109

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-09Bibliographically approved

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Evangelopoulos, Panagiotis
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School of Industrial Engineering and Management (ITM)
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