Proceedings of ECOS 2002, Berlin (Germany) July 3-5, 2002, Vol. 2, pages 1302-1309

ABSTRACTWaste streams that contain large fractions ofhalogenated compounds, such as poly vinylchloride (PVC) and brominated flameretardants (BFRs) cannot be incinerated orotherwise thermally treated straightforward.These fractions are unwanted due to highrisks of corrosion, dioxins/furans formation,the volatility of metal chlorides and the costsof HCl removal from the flue gases. Alsoproblematic are polymer foams that containCFC (chlorofluorocarbon)-type ozonedepleting substances (ODS).

BFRs are widely used in electronic andelectric equipment, furniture and officeequipment. While increasing fire safety, BFRsare problematic for thermal treatment of wastestreams such as waste electric and electronicequipment (WEEE). They interfere with therecovery of valuable metals from WEEE,besides the risk of ODS emissions such asmethyl bromide.

This paper reports from experimental researchon combustion of high-PVC solid waste (seealso ECOS2000 and ECOS2001), andthermal processing of WEEE aiming at therecovery of valuable metals.

INTRODUCTIONPlastic production is steadily increasingworldwide, faster than options are beingdeveloped for recycling wastes that containlarge amounts of plastics. Especially for polyvinyl chloride (PVC), mostly used in what arecalled long-term applications there is thereforea need for new ways of waste processing.Since PVC contains over 50%-wt chlorine (Cl)it is not recommended to burn solid wastes ifPVC represents more than, say, 5% of thetotal weight of the “fuel”. Reasons for this arethe potentially high emissions of HCl andassociated problems such as corrosion andthe risk of dioxins and furans formation.Recently it was reported that around 90% ofthe plastics in Swedish waste from thebuilding sector was PVC [1], whilst in Finlandmore than 90% of the chlorine found in the dryfraction of household waste was reported tobe PVC [2]. The first part of this paper willaddress a process for the combustion of high-PVC solid wastes, producing heat whilerecovering HCl.

Brominated flame retardants (BFRs) arewidely used, often together with antimony-based flame retardants, in electronic andelectric equipment, furniture and officeequipment. While this increases the fire safetyfor these products, the BFRs are problematicwhen thermal processes are used during the

THERMAL PROCESSING OFCHLORINE- AND BROMINE- CONTAINING WASTES

Ron Zevenhoven, Loay Saeed and Antti Tohka

Helsinki University of TechnologyLaboratory for Energy Engineering and Environmental Protection

PO Box 4400, FIN-02015, Espoo, Finlandron.zevenhoven@hut.fi, loay.saeed@hut.fi, antti.tohka@hut.fi

tel. +358 9 4512847 / 4513626 / 4513635fax +358 9 4513418

treatment of waste streams from theseproducts such as waste electric and electronicequipment, WEEE. Not only do the BFRsnegatively effect the incineration of, forexample, old furniture: there is a potential forthe emission of ozone depleting substances(ODS) such as methyl bromide [3]. Also theformation of brominated analogues of dioxinsand furans, PBDD/Fs (poly brominateddibenzo -p- dioxins and - furans) is possible.Finally, they interfere with thermal processesthat aim at the recovery of, for example,valuable metals from WEEE waste. Thesecond part of this paper deals with thermalprocessing of two types of WEEE and theeffect of the BFRs present in these wastes.

THERMAL PROCESSING OF PVC-CONTAINING WASTESThe process for two-stage combustion of high-PVC solid waste with HCl recovery [4] isbased on experimental findings that PVC canbe decomposed into HCl and a low-chlorine orchlorine-free residue by heating totemperatures of around 300-350°C [5-8]. Asimplified scheme of the process as it is beingassessed and optimised at Helsinki Universityof Technology is given in Figure 1.

High-PVC solid waste is fed to a fluidized bed(FB) pyrolysis reactor, where it is heated up toabout 350°C as to release (most of) thehydrogen chlorine (HCl). The gas used for thefluidization in this first reactor is nitrogen (N2)in order to avoid any risk of dioxins and furansformation.

The gases from the first reactor will containmainly N2, HCl, H2O and small amounts ofother gases. The solid residue, which includesthe hydrocarbon residue from the PVC plusthe rest of the incoming fuel, can becombusted as any other low-chlorine orchlorine-free solid fuel. This is accomplishedin the second reactor at around 800°C-850°Cwithout environmental hazard or corrosionproblems.

A theoretical study using process simulationsoftware PROSIM showed that the processmay have a thermal efficiency of approx. 37%,depending on the pyrolysis temperature, PVCcontent in the solid waste and the moisturecontent in the solid waste [9-12]. Thisefficiency is higher than for a conventionalincineration plant that would have approx.33% thermal efficiency. These calculationswere based on wood/PVC fuel mixtures.

A test facility was built at Helsinki University ofTechnology at Otaniemi, Espoo, based on:1. kinetic data on de-hydrochlorination for a

typical PVC [5,7,8] and on combustion ofchars from PVC and wood [6]; and

2. process optimisation calculations for a 40MWthermal plant design case [9-10], scaleddown from 40 MW to 40 kW thermal fuelinput.

Reactor 1 is a bubbling FB reactor (innerdiameter 0.4 m, height 0.8 m) made ofstainless steel ASTM 316. The fluidisingmedium is nitrogen. This BFB is operated inthe temperature range 300 - 400°C: 350°Cmay be the optimum temperature forproducing low-chlorine or chlorine-free fuel inthis dehydrochlorination reactor (with a solidsresidence time of approx. 30 minutes) withoutsignificantly pyrolysing any of the othercombustible fractions [8]. Silica sand (meanparticle size 0.3 mm) is used as bed material.

Reactor 2 is a circulating FB combustor (innerdiameter 0.11 m, height 2.3 m) also made ofstainless steel ASTM 316. The fluidizing gasis air and the reactor operates at atemperature of 800-850°C. This air will bepreheated to approx. 600°C with heating coilsuntil char from the first reactor can provide

High chlorinesolid waste

Hot sand

Reactor 2

700-900°C

Flue gas to heatrecovery boiler

HCl + water+ N2

Reactor 1

200-400°C

AirHeat exchanger

Dry chlorine free fuel

+Cold Sand

Hot sand

Cooling

Cooling

Makeupsand

Nitrogen

Ash+Sand

Fig. 1 Two-stage combustion of high-PVCsolid waste with HCl recovery:simplified process scheme

sufficient combustion heat. The coolingsystem of this CFBC is divided into three partsin order to cool separate parts of the reactorwhen necessary. For process control and datalogging, several probes are connected to acomputer (PC), i.e.19 signals for temperature,11 for pressure, 5 for flow rate and one signalfrom a pH meter (see below).

The sand in the CFBC exist gas is collectedby a high efficiency cyclone operated with inletvelocity about 15 m/s. The collected sand willbe cooled to below 400°C before returning tothe BFB by an FB heat exchanger with water.The fluidizing medium is nitrogen gas. Thisheat exchanger will also act as a non-mechanical valve to prevent any pyrolysisgases from passing to the flue gas exit. A sealpot-type non-mechanical valve between theBFB reactor and the CFBC prevents any flowof air or combustion gases to the BFB.

The pyrolysis gases from the BFB are cooledto 80°C by exchanging heat with water. Afterthat the gases are fed to an NaOH/watersolution to separate the HCl from thepyrolysed gas, which mainly contains N2. TheHCl will be neutralized to produce NaCl andwater. (For a larger scale process, HCl is tobe recovered as hydrochloric acid!) Bymeasuring the pH of the solution the HClconcentration can be followed.

The gases from both FB reactors will beanalyzed as well in order to evaluate processefficiency and to see if there is any release ofchlorine, HCl or traces of dioxins.Concentrations of HCl and several otherspecies in the pyrolysis gas from the BFBpyrolyser and the flue gases from the CFBCare measured with a Fourier transforminfrared (FT-IR) spectrometer (GasmetInstruments Temet type DX-4000).

Two photographs of the facility are given inFigure 2. At the time of finalising this paper,the performance of the two “loops” in the testrig, i.e. 1) pyrolysis reactor / HCl removal frompyrolysis gas / booster blower / pyrolysisreactor, and 2) pyrolysis reactor / combustionreactor / cyclone / heat recovery / pyrolysisreactor are being tested separately. After this,

the “loops” will be connected and operatedsimulataneously. Also, the temperature,pressure and pH measurement equipment isbeing tested, and the FT-IR gas analyser isbeing integrated with the test rig. Experimentswill be conducted during March-April 2002,with PVC/wood and PVC/coal mixtures.

One last feature that will be studied is thatprocessing of waste streams containing PVCinvolves also trace elements and heavymetals such as lead (Pb), cadmium (Cd) butalso the less harmful calcium (Ca) and zinc(Zn). These are added to PVC for improvingits stability against heat, chemicals, ultra-violetirradiation etc. Depending on the type of PVCand the other components in the waste mix,metals such as Pb may react with HCl to formvolatile metal chlorides or may be trapped bythe char. Some work on this was recentlypublished [13] for pyrolysis of mixturescontaining PVC at 500-700°C. As to obtainsome indication on the amounts of traceelements and heavy metals present in PVCwaste, six typical samples were analysed.Results of these analyses are given in Table1.

Table 1 Chemical composition of six typical waste-PVC fractions (dry)

C %-wt H %-wt Cl %-wt Pb %-wt Cd %-wt37 - 41 4.6 - 5.1 46 - 53 0 - 4.0 0 - 0.12

Sn %-wt Ca %-wt Zn mg/kg Ba mg/kg0 – 0.25 0 – 2.8 0 - 36 0 - 1020

CFB combustor (3 cooling sections)Cyclone

HCl recovery (in NaOH/water)

Return sand cooler (FB)

Pyrolysis reactor

Fig. 2 Impression of the test facility atHelsinki Univ. of Technol. (Oct. 01)

BROMINATED FLAME RETARDANTS,BFRsAround 350 chemical compounds have beenregistered as flame retardants of whicharound 200 find commercial application. ABFR may be defined as “a non-organophosphoros organic compound where one ormore hydrogen atoms are replace by bromine”[14]. This definition excludes ammoniumbromide and brominated organophosphates.BFRs contain 50-95 %-wt of bromine, and canbe separated into aromatic, aliphatic andcyclo-aliphatic – see several important BFRsin Figure 3. The aromatic BFRs can bedivided into three types, i.e. polybrominatedbiphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA) and its derivates, andpolybrominated biphenyls (PBBs). Of thecycloaliphatic BFRs compounds,hexabromocyclododecane (HBCD) is the mostimportant. Aliphatic BFRs are not used inlarge amounts since they are less stable thanaromatic BFRs; they may be more effective atlower temperatures, however.

BFRs are used in plastics and textiles in orderto comply with fire safety regulations. InWestern Europe as well as on a global scale,

BFRs represented ~15% of the totalconsumption of flame retardant during the late1990s. Around 75 % of the BFRs are used inplastics, the other 25 % is used in textiles,rubbers, paint, wood, paper and adhesives.Also important is the distinction between“additive” and “reactive” use, where the latterimplies a chemical reaction between the FRand the polymer resin, for example in epoxyresins for printed circuit boards or in rigidpolyurethane (PUR) foams. Additive FRs aremuch less volatile than reactive FRs; FRssuch as TBBPA lose their identity when usedas a reactive BFR [14].

Since the late 1980s the use of PBDE-typeBFRs is declining after several studiespinpointed them as a health andenvironmental hazard, partly because of theirhigh potential to form polybrominated–p-dibenzodioxins and furans (PBDD/Fs). Theirmarket share was taken over by TBBPA andnon-halogenated flame retardants [16]. Fromthe viewpoint of product recycling or chemicalrecycling, BFR-containing polymers such asPUR foams, extruded polystyrene (XPS) andprinted circuit boards and other types ofWEEE are considered problematic [16]. Onthe other hand, BFR-containing wastes arereceiving increased attention for combinedrecovery of bromine (as HBr or NaBr) andenergy.

THERMAL PROCESSING OF WASTESCONTAINING BFRs: WEEEAs part of research under an EU 5th

framework R&D “Growth” project [17], thethermal decomposition of two types of WEEEwas analysed by thermogravimetric analysis(TGA) combined with on-line analysis of theproduct gases by Fourier transform infrared(FT-IR) analysis.

The experimental set-up is shown in Figure 4.The samples are heated (at 10 K/min) up to1000 °C in a gas atmosphere that contains acertain amount of oxygen (21 or 2 %-vol) innitrogen, while the mass is measured asfunction of time, i.e. temperature. At the sametime, the concentration of the gases CO2,H2O, CO, CH4, HCN, NO, N2O, HCl and HBr

Fig. 3 Several brominated flameretardants [15]

is measured using FT-IR, covering the IRspectrum over the range 950-4000wavenumbers (cm-1).

Two types of typical, BFR containing WEEEmaterials were analysed: computor monitorhousing scrap and electronic circuit boardscrap. The results of proximate and ultimateanalysis of these two is given in Table 2.Besides a different bromine content themonitor housings have a higher chlorinecontent and a much lower nitrogen contentthan the printed circuit boards, the latter dueto the presence of ABS (acrylonitrile–butadiene-styrene).

Table 2 Composition of two typicalBFR-containing WEEE

%-wt

Scrappedcomputermonitor

housings

Scrappedelectronic

circuit boards

Moisture 0.1 1.7Volatiles (dry) 84.7 63.1

Ash (dry) 10.6 20.1C-fix a (dry) 4.7 16.8

C (dry) 75.0 44.2H (dry) 7.7 5.0N (dry) 0.9 3.7O (dry) 7.3 22.0S (dry) 0.12 0.03Cl (dry) 0.21 0.02Br (dry) 2.2 5.0Sb (dry) 0.45 0.02Si (dry) 0.25 2.9Cu (dry) 0.14 4.2Ti (dry) 3.5 n.a.b

Others (dry) 2.2 12.9LHV c (dry)

(MJ/kg)22.3 15.8

a by differenceb not analysedc Lower heating value

The result of the TGA/FT-IR test with themonitor housings is given in Figure 5, showinga mass loss only at temperatures below 700K, after which approx. 1/3 of the initial massremains. The corresponding concentration ofhalogen gases HCl and HBr plus those of themajor oxidation products CO2 and H2O are

given in Figure 6. A single peak for HCl isseen at 560 K, while the emissions of H2O andCO2 peak at 640 K. Clearly, chlorine releaseoccurs much earlier than the main oxidation ofthe sample.

Surprisingly enough, the concentration of HBrin the product gases equals zero during theentire test. Discarding the possibility that theBr stays in the sample and will be found in thefinal residue there are two explanations for

Fig. 5 TGA result from scrapped monitorhousings, in air, heating rate 10 K/s

0

100

200

300

400

500

300 500 700 900 1100 1300

Temperature (K)

Mas

s (m

g)

-0.8

-0.6

-0.4

-0.2

0

0.2

Der

. mas

s dm

/dt

(mg/

s)

mass

dm/dt

1865

0

100

200

300

300 500 700 900 1100 1300Temperature (K)

HC

l, H

Br

(pp

m)

0

1

2

3

CO

2 , H

2O (

%-v

ol)HBr

HClCO2H2O

1865

Fig. 6 Concentration of HBr, HCl, CO2 andH2O in the product gas from monitorhousings, in air, heating rate 10 K/s

ThermoThermobalancebalance

1. Air1. Air2. N2. N22 /O/O2 2 93/793/73. N3. N22 /O/O2 2 98/298/2

FTIR analyserFTIR analyserCO, COCO, CO22, , HClHCl, , HBrHBr, CH, CH44 ,,

and NO, NOand NO, NO22 ,N,N22OO+ some others+ some othersGasGas

SampleSample~500 mg~500 mg

20 20 →→→→ 1000 1000°°CCheating rate 10 K/minheating rate 10 K/min

Fig. 4 Experimental set-up for the TGA-FTIR tests

this:

1. Br is released from the sample as aspecies other than HBr, and this is nothydrolysed to HBr either; or

2. HBr is formed but is immediately oxidisedto Br2 via the “Bromine Deacon reaction”

2HBr + ½O2 ó Br2 + H2O (R1)

It follows from free energy minimisationcalculations that the equilibrium constant forreaction (R1) equals

T.

pp

pplnKln

HBrO

OHBrp

1673525568

22

22 +−=

⋅

⋅=

(1)

which with pO2 = 0.2 bar and pH2O < 0.05 barduring the test shows that the equilibrium willbe very much at the side of Br2, especially attemperatures below 700 K. Even for a gaswith, say, 10 %-vol water the situation wouldnot be very different. This hypothesis may betested by adding HBr to the inlet gas andverify whether the same result would beobtained. Another option would be to increasethe heating rate.

Figure 7 gives the FT-IR spectrum at 367°C,corresponding to the peak in Figure 5. Clearlyshown are peaks for CO2 (2300-2400 cm-1),H2O (1300-1900 cm-1 and 3500-4000 cm-1),CH (~1400 cm-1 and 2800-3000 cm-1) andmaybe for CH3Br (~3000 cm-1, ~1300 cm-1,~1000 cm-1, ~1500 cm-1) [18]. No peaks areseen for HBr (~2550 cm-1) whilst the peak forbromobenzene lies outside the range ofmeasurement (~755 cm-1) [19]. For 287°C,where the peak for HCl is seen in Figure 6,the FT-IR spectrum is shown in Figure 8.

Figure 9 gives the TGA result for scrappedprinted circuit boards during heat-up in air at10 K/min. The corresponding gas analysis forHBr, HCl, H2O and CO2 is given in Figure 10.Here, significant mass losses are found at 586K and 732 K, respectively, corresponding to35 % of the mass in both stages. While no

significant further mass loss is recorded above800 K, Figure 10 shows a release of HCl fromthis point onwards. Apart from somescattered, small peaks, also here no HBr wasdetected by the FT-IR.

Fig. 9 TGA result from scrapped electroniccircuit boards, in air, heating rate 10K/s

0

150

300

450

600

300 500 700 900 1100 1300Temperature (K)

Mas

s (m

g)

-1.4-1.2-1-0.8-0.6-0.4-0.200.2

Der

. mas

s dm

/dt

(mg/

s)mass

dm/dt

1866

Fig. 7 FT-IR spectrum of the product gasfrom monitor housings, in air,heating rate 10 K/s, at 367°C

Monitor housings scrap 367 °C (640 K), in O2/N2 20/80 %, 10 K/min

-0.1

0.2

0.5

0.8

1.1

500 1000 1500 2000 2500 3000 3500 4000Wavenumber (cm

-1)

Inte

nsity

(a.

u.)

Fig. 8 FT-IR spectrum of the product gasfrom monitor housings, in air,heating rate 10 K/s, at 287°C

Monitor housings scrap 287 °C (560 K), in O2/N2 20/80 %, 10 K/min

-0.02

0.02

0.06

0.1

500 1000 1500 2000 2500 3000 3500 4000Wavenumber (cm-1)

Inte

nsity

(a.u

.)

The FT-IR spectra corresponding to the masslosses at 586 K and 732 K are given inFigures 11 and 12, respectively. Again, themain peak is for CO2 in both Figures, and

maybe some CH3Br in Figure 11, at 586 K.Nothing points to presence of HBr in the gas.

These two tests were repeated in a 98 %/2 %(vol/vol) N2/O2 atmosphere: the results fromthe TGA are given in Figure 13 and 14 for themonitor housings and the electonic circuitboards, respectively. A first result is that themass loss occurs over wider temperatureranges.

The monitor housings here show a secondmass loss stage above 750 K, whilst nosignificant amounts of HCl are detected(Figure not given here), as opposed to thepeak in Figure 6. The main oxidation of thesample to CO2 and H2O is at 500 K and near800 K. For the electronic scrap, the secondpeak shown in Figure 9 for air is “smearedout” over the temperature range 700-1300 Kin Figure 14. During this test, no HCl wasmeasured by the FT-IR (Figure not givenhere), whilst a continous release of HBr was

Electronic circuit board scrap 313 °C (586 K), in O2/N2 20/80 %, 10 K/min

-0.1

0.2

0.5

0.8

1.1

500 1000 1500 2000 2500 3000 3500 4000

Wave number (cm-1

)

Inte

nsity

(a.u

.)

1866

Fig.11 FT-IR spectrum of the product gasfrom scrapped electronic circuitboards, in air, heating rate 10 K/s,at 313°C

Fig.12 FT-IR spectrum of the product gasfrom scrapped electronic circuitboards, in air, heating rate 10 K/s,at 459°C

Electronic circuit board scrap 459 °C (732 K), in O2/N2 20/80 %, 10 K/min

-0.3

0.7

1.7

2.7

500 1000 1500 2000 2500 3000 3500 4000Wavenumber (cm

-1)

Inte

nsity

(a.u

.)

1866

Fig.10 Concentration of HBr, HCl, CO2 andH2O in the product gas fromscrapped electronic circuit boards inair, heating rate 10 K/s

0

10

20

30

300 500 700 900 1100 1300

Temperature (K)

HC

l, H

Br

(pp

m)

0

1

2

3

CO

2 ,

H2O

(%

-vo

l)HBrHClCO2H2O

18660

100

200

300

400

500

300 500 700 900 1100 1300Temperature (K)

Mas

s (m

g)

-0.8

-0.6

-0.4

-0.2

0

0.2

Der

. mas

s d

m/d

t (m

g/s

)massdm/dt

1885

Fig. 13 TGA result from monitor housingsin N2/O2 98 %/2 %, heating rate 10K/min

Fig. 14 TGA result from scrappedelectronic circuit boards in N2/O2

98 %/2 %, heating rate 10 K/min

0

150

300

450

600

300 500 700 900 1100 1300

Temperature (K)

Mas

s (m

g)

-1

-0.75

-0.5

-0.25

0

Der

. mas

s dm

/dt

(mg/

s)

massdm/dt

1887

measured between 300 K and 600 K. Thissample is oxidised to CO2 and H2O mainly at800-1000 K.

Altogether, there is a significant effect of thepresence of oxygen in the surrounding gas.The temperature at which, and in which form,the bromine from the flame retadardant isreleased is far from clear. One conclusion,though, is that HBr is not the most importantbromine species to be considered whenconsidering bromine emissions from thermalprocessing of waste streams containingbrominated flame retardants. Further tests willaddress the effect of heating rate, gasatmosphere and the effect of bromine“scavengers” such as NaOH.

ACKNOWLEDGEMENTSThe work on PVC-containing wastes is part ofthe Finnish national research program ”Wasteto REF and Energy” (1998-2001) and fundedby the Finnish Technology Agency TEKES,the Finnish Plastic Industries Federation,Foster Wheeler Energy Oy, Borealis PolymersOy and received support also from FortumFoundation. The work on BFR containingmaterials and WEEE is supported by EkokemOy (“apurahoitus 2001”) and the EU 5th

framework programme “Growth” projectHaloclean-conversion, contract no. G1RD-CT-1999-00082 (2000-2002). Prof. Carl-JohanFogelholm is acknowledged for many usefulcomments and suggestions.

REFERENCES[1] Thormark, C. “Conservation of energy andnatural resources by recycling building waste”Resources, Conservation and Recycling, Vol. 33,2001, pp. 113-130[2] Hietanen, L., Waste to REF and Energy –Annual Review, May 23, 2000, Tekes/VTT,Helsinki (in Finnish)[3] Stegou-Sagia, A., Simos, G., “Internationalpolicies and legislation on ozone-depletingsubstances” Proceedings, ECOS‘2001, Istanbul,Turkey, Vol. 2, 2001, pp. 581-588[4] Finnish patent application FI-20001331 (June 2,2000); International PCT applicationPCT/EP01/06334 (June 4, 2001)[5] Bockhorn, H., Hornung, A., Hornung, U.,Teepe, S., Weichmann, J., ”Investigation of thekinetics of thermal degradation of commodityplastics”, Comb. Sci. and Technol., Vol. 116-117,

1996, pp. 129-15[6] Zevenhoven, R., Karlsson, M., Hupa, M.,Frankenhaeuser, M. ”Combustion and gasificationproperties of plastics particles”, J. Air & WasteManage. Assoc., Vol. 47(8), 1997, pp. 861-870[7] Bockhorn, H., Hentschel, J., Hornung, A.,Hornung, U. “Environmental engineering: stepwisepyrolysis of plastics waste”, Chem. Eng. Sci., Vol.54, 1999, pp. 3043-3051[8] Zevenhoven R, Axelsen E. P., Hupa M.“Pyrolysis of waste-drived fuel mixtures containingPVC”, FUEL, Vol. 81(4), 2002, pp. 507-510[9] Zevenhoven R., Saeed L., Fogelholm C. J.,“Optimization of a two-stage combustion processfor high-PVC solid wastes with HCl recovery”,Proceedings ECOS’2000, Enschede, theNetherlands, Vol. 4, 2000, pp. 1959-1970.[10] Saeed, L., Two-stage combustion of high-PVC solid waste with HCl recovery, Lic. Tech.thesis, Helsinki Univ. of Technol., June 2000[11] Saeed, L., Zevenhoven, R., Fogelholm, C. -J., “A comparison between two-stage combustionof high-PVC solid waste and conventionalincineration plants”, Proceedings, ECOS’2001,Istanbul, Turkey, Vol. 2, 2001, pp. 527-535.[12] Saeed, L., Zevenhoven, R."Comparisonbetween two-stage waste incineration with HClrecovery and conventional incineration plants"Energy Sources, Vol. 24(1), 2002, pp. 41-57[13] Jung, C.G., Fontana, A. “Pyrolysis: productionof unleaded substitution fuels from contaminatedwaste” presented at IChemE meeting Incineration2001, Brussels, Belgium, July 2-4, 2001[14] Lassen, C., Løkke, S., Hansen, L.I.,Brominated flame retardants – Substance flowanalysis and substitution feasibility study,Environmental project report Nr. 494, DanishEnvironmental Protection Agency, CopenhagenDenmark, 1999[15] picture by H. Bockhorn and A. Hornung,University of Karlsruhe, Germany (2000)[16] Tohka, A., Zevenhoven, R. “Brominated flameretardants – a nuisance in thermal wasteprocessing ?” accepted for presentation at theTMS Fall 2002 Extraction and Processing DivisionMeeting on Recycling and Waste Treatment inMineral and Metal Processing: Technical andEconomic Aspects, Luleå, Sweden, June 2002[17] http://www.haloclean.org[18] Chu, P.M., Guenther, F.R., Rhoderick, G.C.,Lafferty, W.J., “The NIST Quantitative InfraredDatabase”, J. Res. Natl. Inst. Stand. Technol., Vol.104, 1999, pp. 59-81[19] Chien, Y.-C., Wang, H.P., Lin, K.-S., Huang,Y.-J., Yang, Y.W. “Fate of bromine in pyrolysis ofprinted circuit board wastes” Chemosphere, Vol.40, 2000, pp. 383-387