34 Pyrolytic Recovery of Raw Materials from Special Wastes GERD COLLIN
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Rütgerswerke AG, D-4100 Duisburg-Meiderich, West Germany
Summary P y r o l y s i s can be used f o r the thermal decomposition of waste materials that are predominantly organic i n nature, e.g. scrap t y r e s , scrap cables, waste p l a s t i c s , shredder wastes, and a c i d sludge. Rotary k i l n s are p a r t i c u l a r l y s u i t a b l e as u n i v e r s a l l y a p p l i c a b l e p y r o l y s i s u n i t s for continuous operation. Highly aromatic p y r o l y s i s o i l s for use as chemical raw materials are obtained at reactor temperatures of about 700 ° G . Such p y r o l y s i s o i l s could form the basis for the production of aromatics such as benzene, naphthalene, and t h e i r homologues, thermoplastic hydrocarbon r e s i n s and precursors of i n d u s t r i a l carbon, when the proven processes for the r e f i n i n g of coal t a r and crude benzene are a p p l i e d .
Numerous p r o j e c t s i n i n d u s t r i a l countries with waste and raw materials problems, i n c l u d i n g the Federal Republic of Germany, have been concerned f o r some years with the t e c h n i c a l possibilities and the economic viability of recovering materials from waste (1, 2). Suitable conversion technologies, s p e c i f i cally for s o l i d wastes of mainly organic nature include p y r o l y s i s processes, i.e. the thermal decomposition i n the absence of oxygen, l e a d i n g to the decomposition of organic substances i n t o char and low molecular gaseous and liquid chemicals (3). Can p y r o l y s i s be considered as a u n i v e r s a l conversion technology for the recovery of raw materials from such wastes and what possibilities are there for the utilization of the p y r o l y s i s products? To c l a r i f y t h i s question, a R and D project 0-8412-0565-5/80/47-130-479$05.00/0 © 1980 American Chemical Society Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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480
THERMAL CONVERSION OF
SOLID WASTES AND
BIOMASS
f o r the p y r o l y s i s o f d i f f e r e n t s p e c i a l wastes, c a r r i e d out j o i n t l y by the companies E i s e n und M e t a l l AG, Rutgerswerke AG, and Veba Oel Umwelttechnik GmbH i s b e i n g d e a l t w i t h among o t h e r s . T h i s p r o j e c t i s s p o n s o r e d by the F e d e r a l M i n i s t r y of R e s e a r c h and T e c h n o l o g y and the M i n i s t r y o f Food, A g r i c u l t u r e and F o r e s t r y o f t h e L a n d N o r t h r h i n e W e s t p h a l i a . The l a b o r a t o r y s c a l e t e s t s began i n 1976, and the semit e c h n i c a l t r i a l s w i l l be c o n c l u d e d by the end of 1979. The development c o s t s have so f a r amounted t o some 10 m i l l i o n DM. W i t h i n the scope o f t h i s p r o j e c t the p y r o l y s i s o f d i f f e r i n g s p e c i a l wastes was i n v e s t i g a t e d f o r the f i r s t time under i d e n t i c a l c o n d i t i o n s . The r e s u l t s r e v e a l p o s s i b i l i t i e s o f how t o p r o d u c e h i g h l y a r o m a t i c p y r o l y s i s o i l s by p y r o l y z i n g h y d r o c a r b o n s c o n t a i n i n g s p e c i a l wastes, such as s c r a p t y r e s , s c r a p c a b l e s , waste p l a s t i c s , s h r e d d e r waste from u s e d c a r s , and a c i d s l u d g e i n an i n d i r e c t l y h e a t e d r o t a r y drum r e a c t o r at a r e a c t i o n t e m p e r a t u r e o f some 700 °G i n y i e l d s up t o above 50 % i n r e l a t i o n t o the o r g a n i c s u b s t a n c e . From t h e s e the c h e m i c a l raw m a t e r i a l s benzene, t o l u e n e , x y l e n e , n a p h t h a l e n e and i t s homologues can be m a n u f a c t u r e d . I n a d d i t i o n , t h e r m o p l a s t i c r e s i n s can be p r o d u c e d by p o l y m e r i z a t i o n of f r a c t i o n s c o n t a i n i n g s t y r e n e , i n d e n e and t h e i r homologues (V) . I n F i g . 1 the concept o f the p y r o l y s i s p l a n t i s d e p i c t e d ; F i g . 2 shows the scheme of the p i l o t p l a n t . The s e m i - t e c h n i c a l c o n t i n u o u s r e a c t o r c o n s i s t s o f a r o t a r y k i l n f u r n a c e D 1 w i t h a t o t a l l e n g t h of 7.7 m, a d i a m e t e r of 0.8 m, and a h e a t i n g zone o f 4.75 m. The t h r o u g h p u t amounts to r o u g h l y 200 kg/h when the r e a c t o r i s i n o p e r a t i o n a t a w a l l tempera t u r e of 700 °G. S o l i d s are d i s c h a r g e d v i a a s o l i d s s e t t l e r u n i t . Condensable p a r t s of the raw p y r o l y s i s gas are s e p a r a t e d by q u e n c h i n g w i t h p y r o l y s i s o i l i n Q 1 , i n d i r e c t c o o l i n g i n W 4-/5 and c o u n t e r c u r r e n t s c r u b b i n g w i t h m e t h y l n a p h t h a l e n e i n Κ 3. The a c i d n o x i o u s gases HC1, SO2 and H2S are removed i n Κ 1 and Κ 2 by c o u n t e r c u r r e n t s c r u b b i n g w i t h water and c a u s t i c soda l y e . The p u r i f i e d p y r o l y s i s gas i s u s e d f o r a u t o t h e r m a l i n d i r e c t h e a t i n g o f the r e a c t o r . The p y r o l y s i s o i l s are s e p a r a t e d from the quench and s c r u b b e r o i l s i n the d i s t i l a t i o n u n i t s Κ 4- and Κ 7/8; t h e y can be f u r t h e r r e f i n e d into c h e m i c a l raw m a t e r i a l s by the a p p l i c a t i o n of p r o c e s s e s u s e d i n u p g r a d i n g c o a l t a r and coke oven benzene. F i g . 3 shows the y i e l d s which can be o b t a i n e d
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
34.
COLLIN
Pyrolytic Recovery of Raw Materials
IWASTESI Pyrolysis · '
Down-stream Drocessina
[NEW RAW MATERIALS!
Scrap tyres
Condensation! and H Scrubber Section!
Heating gas for captive use Sulphur Hydrochloric acid
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1
7
Scrap cables ^ Shredder waste from scrapped"" 7oo°C cars Plastic wastes
HI:
Pyrolysis oil
Solids removal
Figure 2.
• BTX - Aromatics - Hydrocarbon resins » Industrial oils • Pyrolysis pitch - Char
Acid sludge _
Figure 1.
481
- Steel Zinc sulphide •Copper, Aluminium
Recovery of raw materials by pyrolysis
Schematic of the semitechnical rotary drum pyrolysis plant
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
THERMAL CONVERSION OF SOLID WASTES AND BIOMASS
482
TYPES
WASTE
OF
YIELDS
Pyrolysis gas
Pyrolysis oil
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[WEIGHT */.]
Pyrolytic char
Metals
12
Scrap
tyres
23
1 7
Waste
plastics
53
30
1 5
13
1 2
33
AO
cables
9
1 4
31
A3
sludge
13
37
3 1
-
Shredder Scrap Acid
Figure 3.
wastes
-
Main product yields of pyrolysis of special wastes
COMPONENTS
1%)
0 F Τ Υ Ρ Ε S Shredder Scrap Waste plastics wastes tyres
W A S Scrap cables
Τ
Ε Acid tar trace
1
2
Benzene
22
22
2U
40
5
Toluene
1 θ
23
1 9
20
1 8
Aliphatic
Hydrocarbons
0.5
trace
^ 8 / 9" benzene Homologues Indane + Homologues
8
5
8
5.5
1 0
Styrene, Indene and Homologues
6
1 0.5
6
4.5
1 0
9
A
1 4
1 0
Naphthalene Naphthalene Homologues Higher bicyclic to tetracyclic Aromatics Pyrolysis Resins (bp > A 5 0 ° C )
Figure 4.
1 0
6
6.5
3.5
5
3
6
8
7
5
2 1
20
20
1 3
4 1
Pyrolysis oils from special wastes (700°C)
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
34.
COLLIN
P y r o l y s i s oi I . crude
DISTI
IPOLYMERIZATION I
^
Pyrolysis residue resins
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483
Pyrolytic Recovery of Raw Materials
Hydrocarbon resins
LLATIO
IEXTRACTÏONI
| * - Refined fractions
C RYSTALLIZATI
™
Naphthalene Carbon black Methyl naphthalenes Wash ° oils Acenaphthene Fluxing oils Phenanthrene Anthracene j
I
*
Plastics Synthetic fibres Motor fuels
Figure 5.
Dyestuffs Plant protecting Plastici zers agents
B ASIC SUBSTANCES
Hydrofining Arom. Extraction [therm, • c a t a l y t i c Polymerization
Cry stal li z a t i o n Granulation
Figure 6.
,
s
Pigment black Carbon black fillers Solvents
Pyrolysis oil processing
JRAW M A T E R l A L | ~ H R E F I N I N G h
Pyrolysis oil crude iDist. 500.000 t
I
ON
.1
ι Benzene Toluene
Cg/g-Benzene homologues
Plastics Adhesi ves Binding agents
I
Ν
CHEMICALS VALUE QUANTITIES [Mill DM) it)
Benzene
100,000"!
Toluene
100,000 J
uo
50.000
75
50,000
25
Hydrocarbon resins
Naphthalene
A 0.000*1
M-naphthalenes
10.000 J
tricyclic Aromatics Carbon black oils Pyrolysis resins (and Losses)
50.000
45
15
100.000
30
500.000
3 30
Pyrolysis oil refinery
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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484
THERMAL CONVERSION OF SOLID WASTES AND BIOMASS
as main products; a breakdown of the chemical comp o s i t i o n of the p y r o l y s i s o i l s i s given i n F i g . 4. The r e f i n i n g of the p y r o l y s i s o i l and the downstream processing i n t o chemical products i s schematically presented i n F i g . 5 ; a balance of products from a l a r g e i n d u s t r i a l r e f i n e r y i s shown i n F i g . 6 f 5 ) » The r e f i n i n g of h i g h l y aromatic p y r o l y s i s o i l s from waste y i e l d s the following range of products: - Benzene f o r further processing i n t o styrene, phenol, cyclohexane and a n i l i n e as intermediate products for thermoplastics and uhermosets, synthetic rubber, synthetic f i b r e s ana dyestuffs, - Toluene for further processing into n i t r o - , c h l o r o and i s o p r o p y l toluenes for polyurethane p l a s t i c s , explosives, dyestuffs, antioxidants and p l a n t p r o t e c t i n g agents, and i f r e q u i r e d , f o r dealkyl a t i o n to benzene, - Cs/9-benzene homologues as high-octane blending components f o r low-lead and non-leaded supergrade gasolines, - Condensed aromatic hydrocarbons such as naphthalene, methylnaphthalenes, acenaphthene, phenanthrene and anthracene for the synthesis of t e x t i l e and pigment dyestuffs, and of aromatic carboxylic acids for P V C - p l a s t i c i z e r esters and polyester resins, - Thermoplastic hydrocarbon r e s i n s and residue r e s i n s f o r the formulation of p l a s t i c s , adhesives and binding agents, - Highly aromatic o i l s as primary products for the production of carbon black f i l l e r s and pigment black for automobile t y r e s , other rubber a r t i c l e s , p r i n t i n g inks and p a i n t s . References 1 . B u n d e s m i n i s t e r des Innern: A b f a l l w i r t s c h a f t s -programm ' 7 5 der Bundesregierung. Bonn, 2 2 . 1 0 . 7 5 2. Umweltbundesamt: M a t e r i a l i e n zum A b f a l l w i r t schaftsprogramm ' 7 5 . M a t e r i a l i e n 6 / 7 6 , B e r l i n 1976 3. C o l l i n , G . ; G r i g o l e i t , G . ; Bracker, G . - P . : Chem.-Ing.-Techn. 50 (1978) No. 10, pp. 836/841 4. C o l l i n , G . ; G r i g o l e i t , G . ; M i c h e l , E.: Chem.-Ing.-Techn. 51 (1979) No. 3, pp. 220/224 5 . C o l l i n , G . : Paper presented on the CRE/MER Conference, B e r l i n , October 1 to 3, 1979 RECEIVED November 20, 1979.
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
